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high - end 18 - bit sensor signal conditioner zssc3218 datasheet ? 2016 integrated device technology, inc. 1 april 20, 2016 brief description the zssc 3 218 is a sensor signal conditioner (ssc) integrated circuit for high - accuracy amplification and analog - to - digital conversio n of a differ ential or pseudo - differential input signal. designed for high - resolution sensor module applications, the zssc3218 can perform offset, span, and 1 st and 2 nd order temperature compensation of the measured signal. developed for correction of resistive bridge or abs olute voltage sensors, it can also provide a corrected temperature output measured with an internal sensor. the measured and corrected sensor values are provided at the digital output pins, which can be configured as i 2 c ? * ( 3.4mhz) or spi ( 20mhz). digi tal compensation of signal offset, sensitivity, temperature, and non - linearity is accomplished via a 26- bit internal digital signal processor (dsp) running a correction algorithm. calibration coeffici ents are stored on - chip in a highly reliable, non - volati le, multi ple - time programmable (mtp) mem ory. pro - gramming the zssc3218 is simple via the serial interface. the interface is used for the pc - controlled cali bration procedure, which programs the set of cali bration coefficients in memory. the zssc3218 provides accelerated signal processing , increased resolution, and improved noise immunity in order to support high - speed control, safety , and real - time sensing applications with the highest requirements for energy efficiency . features ? flexible, programmab le analog front - end design; up to 1 8 - bit analog - to - digital converter (adc) ? fully programmable gain amplifier for optimizing sensor s ignals: g ain range 6.6 to 216 (linear) ? internal auto - compensated temperature sensor ? digital compensation of individual sens or offset; 1 st and 2 nd order digital compensation of sensor gain as well as 1 st and 2 nd order tem perature gain and offset drift ? programmable interrupt operation ? high - s peed s ensing: e.g. 1 6 - bit conditioned sensor signal measure ment rate >5 00s -1 ? typical sensor elements can achieve an accu - racy of better than 0. 1 0 % fso ** at - 40 to 8 5 c benefits ? integrated 26- bit calibration math digital signal processor (dsp) ? fully corrected signal at digital output ? layout customized for die - die bonding with sensor for high - density chip - on- board assembly ? o ne- pass calibration minimizes calibration costs ? no external trimming , filter , or buffering com - ponents required ? highly integrated cmos design ? integrated reprogrammable non - volatile memory ? excellent for low - voltage and low - power battery applications ? optimized for operation in calibrated resistive (e.g. , pressure) sensor or calibrated absolute voltage (e.g. , thermopile) sensor modules physical characteristics ? supply voltage range: 1. 6 8 v to 3.6v ? current consumptio n : 1 . 0 m a ( operating mode) ? sleep state current : 2 0n a ( typical ) ? temperature resolution: < 0.00 3 k /lsb ? best - in - c lass e nergy - e fficiency: with 16 - bit resolution: <1 4 0pj/step with 18 - bit resolution: < 50 pj/step ? oper ation temperature: ? 40c to + 8 5 c ? small die size ? delivery options: die for wafer bonding * i 2 c? is a trademark of nxp. ** fso = full scale output . zssc3218 application example vssb vdd inn vddb vss eoc res mosi sda sclk scl sensor element vddb vssb inp(+) inn(-) inp miso ss stacked-die sensor module vdd vss microcontroller vdd vss signal output / post-processing ss miso mosi sda sclk scl battery zssc3218 res eoc
high - end 18 - bit sensor signal conditioner zssc3218 datasheet ? 2016 integrated device technology, inc. 2 april 20, 2016 applications ? barometric altitude measurement for portable navigation or emergency call systems ? altitude measurement for car navigation ? weather forecast ? fan control ? industrial, pneumatic , and liquid pressure ? high - resolution temperature measurements ? object - temperature radiation (via thermopile) zssc3218 block diagram sales code description package ZSSC3218BI1B die ? temperature range: ? 40c to +85 c ; thickness 304 m unsawn wafer zssc3218bi2b die ? temperature range: ? 40c to +85 c ; t hickness 725 m (w/o backlapping) unsawn wafer zssc3218bi3r es pqfn24 ? temperature range: ? 40c to +85 c ; engineering samples packaged die corporate headquarters 6024 silver creek valley road san jose, ca 95138 www.idt.com sales 1- 800- 345- 7015 or 408 - 284- 8200 fax: 408- 284- 2775 www.idt.com/go/sales tech support www.idt.com/go/support disclaimer integrated device technology, inc. (idt) reserves the right to modify the products and/or specifications described herein at any time, without notice, at idt's sole discretion. performance specifications and operating parameters of the described products are determined in an independent state and are not guarante ed to perform th e same way when installed in customer products. the information contained herein is provided without representation or warranty of any kind, whether express or implied, includin g, but not limited to, the suitability of idt's products for any particular pur pose, an implied warranty of merchantability, or non - infringement of the intellectual property rights of others. this document is presented only as a guide and does not convey an y license under intellectual property rights of idt or any third parties. idt 's products are not intended for use in applications involving extreme environmental conditions or in life support systems or similar devices where the failure or malfunction of an idt product can be reasonably expected to significantly affect the health o r safety of users. anyone using an idt product in such a manner does so at their own risk, absent an express, written agreeme nt by idt. integrated device technology, idt and the idt logo are trademarks or registered trademarks of idt and its subsidiaries in the united states and other countries. other trademarks used herein are the property of idt or their respective third party owners. for datasheet type definitions and a glossary of common terms, visit www.i dt.com/go/glossary . all contents of this document are copyright of integrated device technology, inc. all rights reserved. sensor bridge agnd / cm generator bias current generator power-on reset temperature reference sensor dsp core (calculations , communication ) mtp system control unit multiplexer pre- amplifier v tp v tn eoc inp inn v dd vssb oscillator clock generator spi i2c tm sclk/scl miso mosi/sda ss v ss voltage regulator power ctr. vreg int a d 18 bit vddb zssc3218 res
zssc3218 datasheet ? 2016 integrated device technology, inc. 3 april 20, 2016 table of contents 1 ic characteristics .......................................................................................................................................... 6 1.1. absolute maximum ratings .................................................................................................................... 6 1.2. operating conditions .............................................................................................................................. 6 1.3. electrical parameters ............................................................................................................................. 7 1.4. power supply rejection ratio (psrr) vs. frequency ........................................................................... 9 2 circuit description ....................................................................................................................................... 10 2.1. brief description ................................................................................................................................... 10 2.2. s ignal flow and block diagram ............................................................................................................ 10 2.3. analog front end .................................................................................................................................. 11 2.3.1. amplifier ......................................................................................................................................... 11 2.3.2. analo g - to - digital converter ............................................................................................................ 13 2.3.3. selection of gain and offset ? sensor system dimensioning ...................................................... 15 2.3.4. temperature measurement ........................................................................................................... 16 2.3.5. external sensor supply: bridge sensors ....................................................................................... 16 2.3.6. external sensor: absolute voltage source sensors ..................................................................... 16 2.4. digital section ....................................................................................................................................... 17 2.4.1. digital signal processor (dsp) core ............................................................................................. 17 2.4.2. mtp memory .................................................................................................................................. 17 2.4.3. clo ck generator ............................................................................................................................. 17 2.4.4. power supervision ......................................................................................................................... 17 2.4.5. interface ......................................................................................................................................... 17 3 functional description ................................................................................................................................. 18 3.1. power up .............................................................................................................................................. 18 3.2. measurements ...................................................................................................................................... 18 3.3. interrupt (eoc pin) ............................................................................................................................... 19 3.4. operational modes ............................................................................................................................... 21 3.4.1. spi/i 2 c? commands .................................................................................................................... 24 3.5. communication interface ...................................................................................................................... 27 3.5.1. common functionality ................................................................................................................... 27 3.5.2. spi .................................................................................................................................................. 28 3.5.3. i 2 c? ............................................................................................................................................... 30 3.6. multiple time programmable (mtp) memory ...................................................................................... 32 3.6.1. programming memory .................................................................................................................... 32 3.6.2. memory contents ........................................................................................................................... 33 3.7. calibration sequence ........................................................................................................................... 41 3. 7.1. calibration step 1 ? assigning unique identification ..................................................................... 41 3.7.2. calibration step 2 ? data collection .............................................................................................. 42
zssc3218 datasheet ? 2016 integrated device technology, inc. 4 april 20, 2016 3.7.3. calibration step 3a) ? coefficient calculations ............................................................................. 43 3.7.4. calibration step 3b) ? post - calibration offset correction ............................................................. 43 3.7.5. ssc measurements ....................................................................................................................... 43 3.8. the calibration math ............................................................................................................................ 44 3. 8.1. bridge signal compensation ......................................................................................................... 44 3.8.2. temperature signal compensation ............................................................................................... 47 3.8.3. measurement output data format ................................................................................................ 48 4 package information and pad assignments ............................................................................................... 49 5 quality and reliability .................................................................................................................................. 53 6 ordering sales codes ................................................................................................................................. 53 7 related documents ..................................................................................................................................... 53 8 glossary ...................................................................................................................................................... 54 9 document revisio n history ......................................................................................................................... 55 table of figures figure 2.1 zssc3218 functional block diagram, resistive - bridge sensor .................................................. 10 figure 2.2 zssc3218 functional block diagram, voltage - source sensor .................................................... 11 figure 2.3 gain and offset setup ................................................................................................................... 16 figure 3.1 interrupt functionality .................................................................................................................... 20 figure 3.2 operational flow chart: power up ................................................................................................ 22 figure 3.3 operational flow chart: command mode and normal mode (sleep and c yclic) ......................... 23 figure 3.4 spi configuration cpha=0 ............................................................................................................ 28 figure 3.5 spi configuration cpha=1 ............................................................................................................ 29 figure 3.6 spi command request ................................................................................................................. 29 figure 3.7 spi read status ............................................................................................................................ 30 figure 3.8 spi read data ............................................................................................................................... 30 figu re 3.9 i 2 c? command request .............................................................................................................. 31 figure 3.10 i 2 c? read status .......................................................................................................................... 31 figure 3.11 i 2 c? read data ............................................................................................................................ 31 fi gure 4.1 zssc3218 pad placement ............................................................................................................ 49 figure 4.2 general pqfn24 package dimensions ........................................................................................ 51 list of tables table 1.1 maximum ratings ............................................................................................................................ 6 table 1.2 operating conditions ....................................................................................................................... 6 table 1.3 requirements for vdd power - on reset .......................................................................................... 7
zssc3218 datasheet ? 2016 integrated device technology, inc. 5 april 20, 2016 table 1.4 electrical parameters ....................................................................................................................... 7 table 2.1 amplifier gain: stage 1 .................................................................................................................. 12 table 2.2 amplifier gain: stage 2 .................................................................................................................. 12 table 2.3 gain polarity .................................................................................................................................. 12 table 2.4 adc conversion times for a single analog - to - digital conversion ............................................... 13 table 2.5 adc offset shift ............................................................................................................................. 14 table 2.6 typical conversion times vs. noise performance with full sensor signal conditioning for azsm, sm, aztm, and tm (bridge - type sensor) .................................................................................... 14 table 3.1 spi/i 2 c? commands .................................................................................................................... 24 table 3.2 get_raw commands .................................................................................................................... 26 table 3.3 general status byte ....................................................................................................................... 27 table 3.4 mode status ................................................................................................................................... 28 table 3.5 mtp memory content assignments .............................................................................................. 33 table 3.6 measurement results of adc raw measurement request (two?s complement) ......................... 48 table 3.7 calibration coefficients (factors and summands) in memory (sign - magnitude) .......................... 48 table 3.8 output results from ssc - correction math or dsp ? sensor and temperature ........................... 48 table 3.9 interrupt thresholds trsh1 and trsh2 ? format as for ssc - correction math output ............. 48 table 4.1 pad assignments ........................................................................................................................... 50 table 4.2 die connection and bond parameter ............................................................................................ 50 table 4.3 physical package dimensions ....................................................................................................... 51 table 4.4 pin assignments pqfn24 ............................................................................................................. 52
zssc3218 datasheet ? 2016 integrated device technology, inc. 6 april 20, 2016 1 ic characteristics 1.1. absolute maximum ratings note: the absolute maximum ratings are stress ratings only. the zssc3218 might not function or be operable above the recommended operating conditions. stresses exceeding the absolute maximum ratings might also damage the device. in addition, extended exposure to stresses above the recommended operating conditions might affect device reliability. idt does not recommend designing to the ?absolute maximum ratings.? table 1 . 1 maximum ratings parameter symbol min typ max units voltage reference v ss 0 0 v analog supply voltage v dd -0. 4 3.63 v voltage at all a nalog and d igital io pins v a_io , v d_io -0. 5 v dd +0. 5 v input c urrent into any p in e xcept res , ss 1) , 2) i in -100 100 ma electrostatic d ischarge tolerance ? human body model (hbm1) 3) v hbm 1 4 000 - v storage t emperature t stor -50 125 c 1) latch - up current limit for res , zmdi - test and ss : 7 0 ma . 2) latch - up resistance; reference for pin is 0v. 3) hbm1: c = 100pf charged to v hbm1 with resistor r = 1.5k ? in series based on mil 883, method 3015.7. esd protection referenced to the human body model is tested with devices in ceramic dual in - line packages (cdip) during product qualification. 1.2. operating conditions the r eference for all voltages is vss. table 1 . 2 operating conditions parameter symbol min typ max unit s upply v oltage v dd 1. 68 - 3.6 v vdd rise time t vdd 200 s bridge current 1) i vddb 1.8 m a 16.5 operation temperature range t amb -40 - 8 5 c e xternal (p arasitic) c apacitance between vddb and vss cl 0.01 50 nf 1) p ower supply rejection is reduced if a current in the range of 16.5ma > i vddb > 1.8ma is drawn out of vddb.
zssc3218 datasheet ? 2016 integrated device technology, inc. 7 april 20, 2016 a dynamic power - on - reset circuit is implemented in order to achieve minimum current consumption in idle mode . the vdd low level and the subsequent rise time and vdd rising slope must meet the requirements in table 1 . 1 to guarantee an overall ic reset ; lower vdd low levels allow slower rising of the subsequent on - ramp of vdd. other combinatio ns m ight also be possible. for example, t he reset trigger can be inf luenced by increasing the power - down time and lowering the vdd rising slope requirement. alternatively, the res pin can be connected and used to control safe resetting of the zssc3218 . res is active - low; a vdd - vss - vdd transition at the res pin leads to a complete ic reset. table 1 . 3 requirements for vdd power - on reset parameter symbol min typ max unit power down time (duration of vdd low level) t spike 3 - - s vdd low level vdd low 0 - 0.2 v vdd rising slope sr vdd 10 - - v/ms 1.3. electrical parameters all parameter values are valid only under the specified operating conditions. all v oltages are referenced to vss. table 1 . 4 electrical parameters note: see important table notes at the end of the table . parameter symbol conditions/comments min typ max unit supply external sensor s upply v oltage, adc r eference v oltage v ddb i nternally generated 1.6 0 1. 6 8 1.7 5 v current consumption i vdd active state, average 1 0 5 0 1500 a sleep state, idle current , 85c 20 250 n a power supply rejection 20 log 10 (v dd /v ddb ) (see section 1.4 ) psr vdd v dd = 1.8v 17 60 88 db v dd = 2v 3 2 65 91 db analog -to - digital converter (adc , a2d ) resolution r adc 12 18 bit adc c lock f requency f adc internal adc clock 0.9 1 1.1 mhz conversion rate f s,raw conversions per second for single 18- bit external sensor a2d conversion (w/o az) 1.1 khz conversions per second for single 16- bit temperature sensor a2d conversion (w/o az) 2.3 khz
zssc3218 datasheet ? 2016 integrated device technology, inc. 8 april 20, 2016 parameter symbol conditions/comments min typ max unit amplifier gain g amp 64 steps 6.6 216 gain error g err referenced to nominal gain -2 .5 - 2 .5 % sensor signal conditioning performance ic accuracy error 1) err a,ic accuracy error for sensor that is ideally linear (in temperature and measurand ) 0. 0 1 % fso conversion rate, 1 8 -b it ssc f s, ssc conversion per second for fully corrected 1 8 - bit measurement 270 300 hz input input voltage range v inp , v inn input voltage range at inp and inn 0.65 1.05 v external sensor bridge resistance r br f ull power supply disturbance rejection ( psrr ) capabilities 1 10 50 k r educed psrr, but full functionality 100 999 power -up start - up time t sta1 v dd ramp up to interface communication (see section 3.1 ) 1 ms t sta2 v dd ramp up to analog operation 2.5 ms wake - up time t wup1 sleep to active state interface communication 0.5 ms t wup2 sleep to active state analog operation 2 ms oscillator internal oscillator frequency f clk 3. 6 4 4. 4 mhz internal temperature sensor temperature resolution - 40c to + 8 5c 0.003 k/lsb interface and memory spi clock frequency f c,spi maximum capacitance at miso line: 40pf at v dd =1.8v 1 20 mhz i2c ? clock frequency f c,i2c 3.4 mhz program time t prog mtp programming time per 16 - bit register 5 16 m s endurance n mtp number of reprogramming cycles 1000 10000 numeric data retention t ret_mtp 1000h at 1 25 c 10 a 1) percentage referred to maximum full - scale output (fso); e.g. for 1 8 - bit measurements: err a,ic [%fso] = 100 max{ | adc meas ? adc ideal | } / 2 1 8 .
zssc3218 datasheet ? 2016 integrated device technology, inc. 9 april 20, 2016 1.4. power supply rejection ratio ( p srr) vs. frequency
zssc3218 datasheet ? 2016 integrated device technology, inc. 10 april 20, 2016 2 c ircuit description 2.1. brief description the zssc3218 provides a highly accurate amplification of bridge sensor signals. the compensation of sensor offset, sensitivity, temperature drift, and non - linearity is accomplished via a 26- bit dsp core running a correction algorithm with calibration coefficients stored in a non - volatil e memory. the zssc3218 can be configured for a wide range of resistive bridge sensor types and for absolute voltage source sensors . a digital interface (spi or i 2 c ? ) enables communication. the zssc3218 supports two operational modes: no rmal m ode and c om mand m ode. normal m ode is the standard operating mode. typically in normal mode, the zssc3218 wakes up from a s leep s tate (low power) , runs a measurement in a ctive s tate , and automatically returns to the sleep s tate . (see section 3.4 for details on operational modes.) 2.2. signal flow and block diagram see figure 2 . 1 and figure 2 . 2 for the zssc3218 block diagram for different input sensors . the sensor bridge supply v ddb and the power supply for analog circuitry are provided by a voltage regulator , which is optimized for p ower supply disturbance rejection (psrr). see section 1.4 for a graph of psrr versus frequency. to improve noise suppression, the digital blocks ar e powered by a separate voltage regulator. a power supervision circuit monitors all supply voltage s and generates appropriate reset signals for initializing the digital blocks. the system control unit controls the analog circuitry to perform the three meas urement types: external sensor , temperature, and offset measurement. the multiplexer selects the signal input to the amplifier, which can be the external signals from the input pins inp and inn or the internal temperature reference sensor signals . a full measurement request will trigger a n automatic sequence of all measurement types and all input signals. figure 2 . 1 zssc3218 functional block diagram , resistive - bridge sensor sensor bridge agnd / cm generator bias current generator power - on reset temperature reference sensor dsp core ( calculations , communication ) mtp system control unit multiplexer pre - amplifier v tp v tn eoc inp inn v dd vssb oscillator clock generator spi i 2 c tm sclk / scl miso mosi / sda ss v ss voltage regulator power ctr . vreg int a d 18 bit vddb zssc 3218 res
zssc3218 datasheet ? 2016 integrated device technology, inc. 11 april 20, 2016 fig ure 2 . 2 zssc3218 functional block diagram, voltage - source sensor agnd / cm generator bias current generator power - o n reset ( por ) temperature reference sensor dsp core ( calculations , communication ) mtp system control unit multiplexer pre - amplifier v tp v tn eoc inp inn v dd vssb oscillator clock generator spi i 2 c tm sclk / scl miso mosi / sda ss v ss voltage regulator power ctr . vreg int a d 18 - bit vddb zssc 3218 res v source the amplifier consists of two stages with programmable gain values. the zssc3218 employs a programmable analog - to - digital converter (adc) optimized for conversion speed and noise suppression. the programmable resolution from 1 2 to 1 8 bit s provides flexibility for adapting the conversion characteristics. to improve power supply noise suppression, the adc use s the bridge supply v ddb as its reference voltage leading to a ratiometric measurement topology if the e xternal sensor is a bridge - type element . the remaining ic - internal offset and the sensor element offset , i.e., the overall system offset for the amplifi er and adc , can be canceled by means of an offset and auto - zero measurement , respectively . the dsp accomplishes the auto - zero , span, and 1 st and 2 nd order temperature compensation of the measured external sensor signal. the correction coefficients are stored in the mtp memory. the zssc3218 supports spi and i 2 c ? interface communication for controlling the zssc3218 , configuration , and measurement result output. 2.3. analog front end 2.3.1. amplifier the amplifier has a fully d ifferential architecture and consists of two stages . the amplification of each stage and the external sensor gain polarity are programmable via settings in the meas urement configuration register sm _config 1 and sm_config2 (address es 1 2 hex and 16 hex ; see section 3.6.2 ) in the mtp memory ( for details, see section 2.4.2 ).
zssc3218 datasheet ? 2016 integrated device technology, inc. 12 april 20, 2016 the first 6 bits of sm _config * are the programmable gain setting s gain_stage1 and gain_stage2 . the options for the programmable gain settings are listed in table 2 . 1 and table 2 . 2 . table 2 . 1 amplifier gain: stage 1 gain_stage1 sm_config bit g2 sm_config bit g1 sm_config bit g0 gain amp 1 0 0 0 6 0 0 1 12 0 1 0 20 0 1 1 30 1 0 0 40 1 0 1 60 1 1 0 80 1 1 1 120 table 2 . 2 amplifier gain: stage 2 gain_stage2 sm _config bit g 5 sm _config bit g 4 sm _config bit g 3 gain amp 2 0 0 0 1.1 0 0 1 1.2 0 1 0 1.3 0 1 1 1.4 1 0 0 1.5 1 0 1 1.6 1 1 0 1.7 1 1 1 1.8 if needed, the polarity of the sensor bridge gain can be reversed by setting the gain_ p olarity bit , which is bit 6 in the sm _config register ( s ee section 3.6.2 ) . changing the gain polarity is achieved by inverting the chopper clock. table 2 . 3 gives the settings for the gain_ p olarity bit. this feature enables applying a sensor to the zssc3218 with swapped input signals at inn and in p ; e.g., to avoid crossing wires for the final sensor module?s assembly. table 2 . 3 gain polarity gain_ p olarity (sm _config bit 6 ) gain setting d escription 0 +1 no polarity change . 1 - 1 gain polarity is inverted . * the register name sm_config is used for general register content and effect explanations for both sm_config1 and sm_config2 as the registers? bit assignments are exactly the same for both registers.
zssc3218 datasheet ? 2016 integrated device technology, inc. 13 april 20, 2016 2.3.2. analog - to - digital converter a n analog - to - digital converter (adc) is used to digitize the amplifier signal. to allow optimizing the trade - off between conversion time and resolution , the resolution can be programmed from 12 - bit to 18 - bit (adc_bits , sm _config register ; section 3.6.2 ) . the adc processes differential input signals. table 2 . 4 adc co nversion times for a s ingle analog - to - digital c onversion r esolution (bits) conversion time in s (typical) 12 140 13 18 5 14 2 50 15 33 5 16 4 70 17 640 18 890 the adc can perform an offset shift in order to adapt input signals with offsets to the adc input range. the shift feature is enabled by setting sm_config register ?s b it [ 15] = 1 ( shift_method = 1). the respective analog offset shift can be set up with b its [14:12], offset in sm_config . the offset s hift causes the adc to perform an additional amplification of the adc?s input signal by factor 2. this must be considered for a correct analog sensor setup by means of the pre - amplifier?s gain, the adc offset shift , and the potential adc gain. the overall analog amplification ???? ????? = ???? ? ?? 1 ? ???? ? ?? 2 ? ???? ??? can be determined for the following potential use cases: ? i f no offset shift is selected, i.e. , shift_method = 0 and offset = 000 in sm_config , ???? ????? = ?? ? ? ? ?? 1 ? ???? ??? 2 ? 1 ? i f adc offset shift is selected, i.e. , shift_method = 1 ( offset is arbitrary) in sm_config , ???? ????? = ???? ? ?? 1 ? ???? ??? 2 ? 2
zssc3218 datasheet ? 2016 integrated device technology, inc. 14 april 20, 2016 table 2 . 5 adc o ffset s hift offset shift in adc sm_config bit 15 (shift_method) offset: sm_config bit 14 offset: sm_config bit 13 offset: sm_config bit 12 gain adc compensation of per centa ge of fset in input signal 0 0 0 0 1 0% 1 0 0 0 2 0% 1 0 0 1 2 6.75% 1 0 1 0 2 12.50% 1 0 1 1 2 19.25% 1 1 0 0 2 25.00% 1 1 0 1 2 31.75% 1 1 1 0 2 38.50% 1 1 1 1 2 43.25% note : if no offset shift will be performed and the adc will not apply the additional gain of factor 2 (leading to gain adc = 1) , then shift_method = 0 and offset = 000 in sm_config must be selected. any other setup with shift_method = 0 and offset 000 leads to erroneous analog setups. table 2 . 6 typical conversion times vs. noise performance with full sensor signal conditioning for az s m, s m, aztm, and tm (bridge - type sensor) adc resolution : temperature sensor adc resolution : external sensor typical measurement duration 1) , measure, (a a hex ) (ms) typical 3 - sigma noise for ssc - corrected output 2) ( counts ) 16 12 2.2 2.4 16 13 2.3 2.5 16 14 2.4 3.0 16 15 2.6 4.4 16 16 2.8 5.7 16 17 3.2 10.5 16 18 3.7 18.0 1) m easurement duration is defined as the time from the high/low transition at the eoc pin at the beginning of the measurement until the low/high back - transition of the eoc signal at the end of a single measurement in sleep mode. 2) reference noise values normalized to the respective e xternal s ensor?s adc resolution, obtained with th e following setup: 20k ? sensor bridge, 25c, gain= 52 , offset= 25% , vdd=1.8v.
zssc3218 datasheet ? 2016 integrated device technology, inc. 15 april 20, 2016 2.3.3. selection of gain and offset ? sensor system dimensioning the optimal gain (and offset) setup for a specific sensor element can be determined by the f o ll owing steps: 1) collect sensor element ?s characteristic, statistical data (over temperature, ambient sensor parameter, and over production tolerances): a. minimum differential output voltage: v min b. maximum differential output voltage: v max note: the best possible setup can only be determined if the absolute value of v max is bigger than the absolute value of v min . if this is not the case, the gain polarity should be reversed by means of the gain_polarity bit in the mtp?s sm_config register . 2) calcula te: a. c ommon mode level, i.e. differential offset of the sensor output: ? ?? = 0.5 ? ( ? ?? ? + ? ? ?? ) b. r elative or percenta ge offset of the sensor output: ? ?? ??? ?? ? ?? ? [ % ] = ? ?? ? ??? C ? ??? ? 100% 3) determine which of the two following cases is valid. a. i f offset sensor [%] > 43% then select offset = 111 (i.e. , 43.25%) b. i f 0% < offset sensor [%] 43% then select offset offset sensor [%] ( offset setup value ; see table 2 . 5 ) 4) the totally required, op timum gain can be determined as ???? ????? , ??? = 1 . 4 ? ? ??? ? ? 1 ? ?????? ???? ?? 100 ? then select nearest gain to gain total,opt , where gain total gain total,opt 5) the gain setup can be separated into the three factors gain amp1 , gain amp2 (for the 2 - stage amplifier) and gain adc (1 for no - shift or 2 for shift operation) according to: gain total = gain amp1 ? gain amp2 ? gain adc . a. i f no offset shift is performed ( shift_method = 0 and offset = 000), the amplifier gain is gain total b. i f an offset shift is performed ( shift_method = 1), the amplifier gain is 0.5 gain total
zssc3218 datasheet ? 2016 integrated device technology, inc. 16 april 20, 2016 figure 2 . 3 gain and offset setup sensor bridge dsp pre - amplifier inp inn vssb spi i 2 c ? a d vddb gain amp 1 gain amp 2 gain adc v differential , in 0 v v amp 1 , out v amp 2 , out v adc , in digital adc out , 18 bit digitize - 1 . 4 v 1 . 4 v 131 k - 131 k gain amp 1 gain amp 2 gain adc , - offset 0 v offset zoom 2.3.4. temperature measurement the zssc3218 provides an internal temperature sensor measurement to allow compensation for temperature effects . see section 1.3 for the temperature sensor resolution . the temperature output signal is a differential voltage that is adapted by the amplifier for the adc input . for temperature measurements , the respective setting s are defined and programmed in the mtp by idt . 2.3.5. external sensor supply : bridge sensors the zssc3218 provides dedicated supply pins vddb and vssb for resistive bridge - type sensors (bit [11]=0 in sm_config , mtp register s 12 hex or 16 hex ) . the adc reference voltages for the sensor bridge measurement are derived from the se internal voltages s uch that bridge supply disturbances are suppressed. the current drive ability of v ddb is limited (see i vddb in section 1.2 ). 2.3.6. external sensor: absolute voltage source sensors the zssc3218 can alternatively process signals from an absolute - voltage source sensor, e.g. a thermopile element. the respec tive input - type selection can be done with bit[11]= 1 in sm_config , mtp registers 12 hex or 16 hex . the respective sensor element must be connected between the pins inp and inn, whereas inn is internally connected to the zssc3218 ? s analog ground (not! being vssb). vddb and vssb should not be connected if an absolute - voltage source sensor is applied. the offset shift should be set to maximum in this case, shift_method = 1 and offset = 111 in sm_config . the required gain can be determined according to the proce dure describe d in section 2.3.3 .
zssc3218 datasheet ? 2016 integrated device technology, inc. 17 april 20, 2016 2.4. digital section 2.4.1. digital signal processor (dsp) core the ? dsp core ? block performs the algorithm for correcting the sensor signal. the re quired coefficients are stored in the mtp memory. when the measurement results are available , the ? end of conversion ? signal is set at the eoc pin if no interrupt - thresh old has been set up (bits[8:7]= 00 in memory register 02 hex ) . the internal eoc information is valid only if both the measurement and calculation have been completed. alternatively, the eoc pin can indicate exceeding or unde rrunning of a certain threshold or leaving of valid - result range as described in section 3.3 . 2.4.2. mtp memory the zssc3218 ?s memory is designed with a real mtp structure. the memory is organized in 16- bit registers that can be re - written multiple ( at least 1000) times . the user has access to a 57 x 16 - bit storage area for values such as calibration coefficients . the required programming voltage is generated internally in the zssc3218 . a checksum (generation with command 90 hex ) is evaluated be f or i ntegrity - check purposes of the entire memory. 2.4.3. clock generator the clock generator provides approximate ly 4mhz , and 1mhz clock signal s as the time base for ic - internal signal processing . the frequency is trimmed during production test. 2.4.4. power supervision the p ower s upervision block as a part of the voltage regulator combined with the digital section monitors all power supplies to ensure a defined reset of all digital blocks during power - up or power supply interruptions. ?brown - out? cases at the supply that do not meet the power - on reset ( por ) requirements ( see table 1 . 3 ) , must be resolved with a reset pulse at the res pin . 2.4.5. interface the zssc3218 can communicate with the user?s communication master or pc via an spi or i 2 c ? interface ? . the interface type is selectable with the very first activity at the interface after power - up or reset , with the first activity being a. if the first command is an i 2 c tm c ommand and ss pin has been inactive until receiving this command, the zssc3218 enters i 2 c tm mode. b. if the first interface action is the ss pin being set to active ( high - active or low - active depend ing on ss_polarity bit[9] in memory interface register 0 2 hex ), then the zssc3218 enters spi mode . during the initiation sequence (after power - up or reset ) , any potential transition on ss is ignored. switching to the spi mode is only possible after the power - up sequence. if ss is not connected, the ss pin internal pull - up keeps the zssc3218 in i 2 c tm mode. to also provide interface ac c essibility in sleep s tate (all features inactive except for the digital interface logic) , the interface circuitry is directly supplied by vdd. ? f unctional i 2 c? interface properties correspond to the nxp i2c? bus specification rev. 0.3 (june 2009) .
zssc3218 datasheet ? 2016 integrated device technology, inc. 18 april 20, 2016 3 functional description 3.1. power up specifications for this section are given in sections 1.2 and 1.3 . on power - up, the zssc3218 communication interface is able to receive the first command after a time t sta1 from when the vdd supply is within operating specifications . the zssc3218 can begin the first measurement after a time of t sta2, from when the vdd supply is operational. alternatively , instead of a power - on- reset, a reset and new power - up - sequence respectively can be trigger e d by an ic - reset signal (high low ) at res pin. the wake up time from sleep state to active state (s ee section 3.4 ) after receiving the a ctivating command i s defined as t wup1 and t wup2 . in c ommand m ode , subsequent commands can be sent after t wup1 . the first measurement start s after t wup2 if a measurement request was sent . 3.2. measurements available measurement procedures are ? az s m: auto - zero (external) sensor measurement ? s m: (external) sensor measurement ? aztm: auto - zero temperature measurement ? tm: temperature measurement az s m: the configuration is loaded for measuring the external sensor ; i.e. , a resistive bridge or a n absolute voltage source . the ? mul t iplexer ? block connects the a mplifier input to the agnd analog ground reference . an analog - to - digital (a2d) conversion is performed so that the inherent system offset for the respective configuration is converted by the adc to a digital word with a resolution according to the respective mtp configuration . s m: the configuration is loaded f or measuring the external sensor; i.e. a resistive bridge or an absolute voltage source . the ?multiplexer? block connects the a mplifier input to the inp and inn pins . an a2d conversion is performed . the result is a digital word with a resolution according to the mtp configuration . aztm: the configuration for temperature measurement s is loaded. the ?multiplexer? block connects the a mplifier input to agnd. an analog - to - digital conversion is performed so that the inherent system of fset for the temperature configuration is converted by the adc with a resolution according to the respective mtp con - figuration. tm: the configuration for temperature measurement s is loaded. the ?multiplexer? block connects the a mplifier input to the inter nal temperature sensor. an a2d conversion is performed . the result is a digital word with a resolution according to the mtp configuration. the typical application?s measurement cycle is a complete ssc m easurement (using the command s a a hex to af hex ; see section 3.4.1 ) with azsm, s m, aztm, and tm followed by a signal correction calculation.
zssc3218 datasheet ? 2016 integrated device technology, inc. 19 april 20, 2016 3.3. interrupt (eoc pin) the eoc pin can be programmed t o operate either as a pure ?measurement busy? and end - of - conversion indicator or as a configurable interrupt indicator. the respective basic operation must be programmed to the int_setup bits [8:7] in register 02 hex ( see table 3 . 5 ) . in addition , one or two 24 - bit - quantized thresholds can be programmed ( trsh1 and trsh2 in memory register s 13 hex , 14 hex , and 15 hex ). the r espective thresholds are programmed left - aligned in the memory ; i.e., they must be programmed with the threshold?s msb i n the memory register?s msb, etc. the number of lsb threshold bits that are used is equal to the number of bits for the selected adc res olution (determined by the adc_bits field in registers 12 hex and 16 hex ) ; unused lsb bits are ignored . the interrupt functionality is only available for digital values from the ssc - calculation unit (i.e., after sensor signal conditioning); raw values cannot be monitored by the interrupt feature. figure 3 . 1 shows the different setup options and the respective response at the eoc pin. the use of the interrupt functionality is recommended for cyclic operation (command ab hex with the respective power - down setup in the interface configuration memory register 02 hex ). t he eoc level continuously represents the respective ssc - measurem ent result s only during cyclic operation . for single or oversample measurement requests without cyclic operation, the eoc output signal is reset to logical zero at the beginning of each new measurement, even though the interrupt thresholds are considered c orrectly at the end of each measurement (setting eoc to logical one or zero is dependent on the interrupt setup) .
zssc3218 datasheet ? 2016 integrated device technology, inc. 20 april 20, 2016 figure 3 . 1 interrupt functionality time measurement result 0 max . threshold 1 threshold 2 time 0 1 eoc / int case a : threshold 1 > threshold 2 time measurement result 0 max . threshold 2 threshold 1 time 0 1 eoc / int case b : threshold 1 < threshold 2 time measurement result 0 max . threshold 1 time 0 1 eoc / int int _ setup = 01 : measurement < threshold 1 time measurement result 0 max . threshold 1 time 0 1 eoc / int int _ setup = 10 : measurement > threshold 1 int _ setup = 11
zssc3218 datasheet ? 2016 integrated device technology, inc. 21 april 20, 2016 3.4. operational modes figure 3 . 2 illustrates the zssc3218 power - up sequence and subseq uent operation depending on the selected interface communication mode (i 2 c? or spi) as determined by interface - related first activities after power - up or reset . if the first command after power - up is a valid i2c? command, the interface will function as an i2c ? interface until the next power - on- reset. if there is no valid i2c? command , but an active signal at the ss pin is detected as the first valid activity, then the interface will respond as an spi slave. with either interface, after the voltage regulators are switched on, the zssc3218 ?s low - voltage section (lv) is active while the r elated interface configuration information is read from memory . then the lv section is switched off , the zssc3218 goes in to sleep state , and t he interface is ready to receive commands. t he interface is always powered by v dd , so it is referred to as the high voltage section (hv). s ee table 3 . 1 for definitions of the command s . figure 3 . 3 shows the zssc3218 operation in normal mode (with two operation principles: ?sleep? and ?cyclic?) and command mode , including when the lv and hv sections are active as indicated by the color legend . the normal m ode automatically returns to sleep state after executing the requested measurements , or periodically wakes up and conducts another measurement according to the setting for the sleep duration configured by cyc_period (bits[14:12] in memory register 02 hex ) . in command mode , the zssc3218 remains active if a dedicated command (start_nom) i s sent, which is helpful during calibration. command mode can only be entered if start_cm is the first command received after por.
zssc3218 datasheet ? 2016 integrated device technology, inc. 22 april 20, 2016 figure 3 . 2 operational flow chart: power u p receive : command hv operation lv operation i 2 c? interface spi interface lv operation ic power on power down ( switch off lv and wait for command ) save : ic id / data / status color legend : received cmd id == ic - id yes no io _ mode := spi execute : data fetch read _ bit == 1 ( data fetch ) yes no data / status from lv commandmode == active || test == 1 yes no power up lv lv operation save : setup / data / status data / status from lv power up lv power down ( switch off lv and wait for command ) rst ( ss )== 1 yes no execute : data fetch nop yes commandmode == active || test == 1 yes no no receive : command i 2 c ? address / cmd valid ? io _ mode = i 2 c ? yes ss pin active ? command := load i / o setup no no yes from this point until next por , the interface selection is fixed i 2 c tm slave address is loaded , and ss _ polarity determines if ss pin is active high or low
zssc3218 datasheet ? 2016 integrated device technology, inc. 23 april 20, 2016 figure 3 . 3 operational flow chart: command mode and normal mode (sleep and cyclic) sleep mode receive: command start_nom execute: command hv operation lv operation color legend: cmd==start_cm yes no get command from hv command mode case (command) regular_cmd invalid_cmd data/status from lv cm active start lv end lv cm inactive execute: command case (command) regular_cmd data/status from lv cyclic measurement? yes no count waiting period power down all lv except oscillator safe command and setup_lv power up all lv invalid_cmd cyclic_active! to hv cyclic_active? no new measurement command or stop_cycle? yes do: setup_lv no stop_cycle reset lv setup_lv:= new command?s setup new command keep existing setup_lv cyclic mode
zssc3218 datasheet ? 2016 integrated device technology, inc. 24 april 20, 2016 3.4.1. spi/i 2 c ? c ommands the spi/i 2 c ? commands supported by the zssc3218 are listed in table 3 . 1 . the command to read an address in the user memory is the same as its address. the command to write to an address in user memory is the address plus 40 hex . the re is a idt - reserved section of memory that can be read but not over - written by the user. table 3 . 1 spi/i 2 c ? commands note: every return starts with a status byte followed by the data word as described in section 3.5.1 . command (byte) return description normal mode command mode 00 hex to 39 hex 16- bit user data read data in the user memory address (00 hex to 39 hex ) matching the command (m ight not be using all addresses ). yes yes 3a hex to 3 f hex 16- bit idt - reserved memory data read data in idt - reserved memory at address (3a hex to 3f hex ). yes yes 40 hex to 79 hex followed by data (0000 hex to ffff hex ) ? write data to user memory at address specified by command minus 40 hex ( address es 00 hex to 39 hex respectively; might not be using all addresses) . yes yes 90 hex ? calculate and write memory checksum (crc) . yes yes a0 hex to a7 hex followed by xxxx hex (see table 3 . 2 ) 24- bit formatted raw data get_raw this command can be used to perform a measurement and write the raw adc data into the output register. the lsb of the command determines how the afe configuration register is loaded for the get_raw measurement (see tab le 3 . 2 ). yes yes a8 hex ? start_nom exit command mode and transition to normal mode (sleep or cyclic) . no yes a9 hex ? start_cm exit normal mode and transition to command mode (as very first command after power - up). yes no aa hex 24- bit formatted fully corrected sensor meas - urement data + 24 - bit corrected temperature data measure trigger full measurement cycle (az s m, s m, aztm, and tm, as described in section 3.2 ) and calc ulation and storage of data in the output buffer using the configuration from mtp . yes yes
zssc3218 datasheet ? 2016 integrated device technology, inc. 25 april 20, 2016 command (byte) return description normal mode command mode ab hex 24- bit formatted fully corrected sensor meas - urement data + 24 - bit corrected temperature data measure cyclic t his command t riggers a continuous full measurement cycle (azsm, sm, aztm, and tm ; see section 3.2 ) and calculation and storage of data in the output buffer using the configuration from mtp followed by a pause determined by cyc_period (b its[14:12] in memory register 02 hex ). yes yes ac hex 24- bit formatted fully corrected sensor meas - urement data + 24 - bit corrected temperature data oversample -2 measure mean value gen- eration: 2 full measurements are conducted ( as in command aa hex ), the measurements ? mean value is calculated , and data is stored in the output buffer using the configuration from mtp ; no power down or pause between the 2 measurements . yes yes ad hex 24- bit formatted fully corrected sensor meas - urement data + 24 - bit corrected temperature data oversample -4 measure mean value generation: 4 full measurements ( as in command aa hex ) are conducted, the measurements ? mean value is calculated, and data is stored in the output buffer using the configuration from mtp ; no power down or pause between the 4 measurements . yes y es ae hex 24- bit formatted fully corrected sensor meas - urement data + 24 - bit corrected temperature data oversample -8 measure mean value gen- eration: 8 full measurements (as in command aa hex ) are conducted, the measurements? mean value is calculated, and data is stored in the output buffer using the configuration from mtp ; no power down or pause between the 8 measurements . yes yes af hex 24- bit formatted fully corrected sensor meas - urement data + 24 - bit corrected temperature data oversample -16 measure mean value generation: 16 full measurements (as in command aa hex ) are conducted, the measurements? mean value is calculated, and data is stored in the output buffer using the configuration from mtp; no power down or pause between the 16 measurements . yes yes b0 hex ? select s m_config1 register (12 hex in memory) f or any measurement using the memory content s for the analog front - end and sensor setup, the respective setup is loaded from the s m_config1 register ; status bit[1]==0 (default) . yes yes
zssc3218 datasheet ? 2016 integrated device technology, inc. 26 april 20, 2016 command (byte) return description normal mode command mode b1 hex ? select s m_config2 register ( 16 hex in memory) for any measurement using the memory contents for the analog front - end and sensor setup, the respective setup is loaded from the s m_config2 regis ter , status bit[1]==1 yes yes bf hex ? stop_cyc this command c auses a power - down halting the update / cyclic measure - ment operation and causing a transition to normal - sleep operation. yes yes fx hex status followed by last 24- bit data nop only valid for spi (see sections 3.5.1 and 3.5.2 ). yes yes table 3 . 2 get_raw commands command measurement afe configuration register a0 hex followed by 0000 hex s m ? sensor measurement sm_config1 register or sm_config2 register . a1 hex followed by ssss hex s m ? sensor measurement ssss is the user?s configuration setting for the measure - ment provided via the interface. the format and pur - pose of configuration bits must be according to the definitions for sm _ c onfig (see table 3 . 5 ). a2 hex followed by 0000 hex s m -az s m ? auto - zero c orrected sensor measurement 1) sm _ c onfig a3 hex followed by ssss hex sm -az sm ? auto - zero c orrected sensor measurement 2) ssss is the user?s configuration setting for the measure - ment provided via the interface. the format and pur - pose of configuration bits must be according to the definitions for sm _ c onfig . a4 hex followed by 0000 hex tm ? temperature measurement idt - defined register a5 hex followed by ssss hex tm ? temperature measurement ssss is the user?s configuration setting for the measure - ment provided via the interface. the format and pur - pose of configuration bits must be according to the definitions for sm _ c onfig and valid for temp erature measu rement in this case (bits [15:12 ] will be ignored). a6 hex followed by 0000 hex tm - aztm ? auto - zero c orrected temperature measurement 1) idt - defined register a7 hex followed by ssss hex tm - aztm ? auto - zero c orrected temperature measurement 2) ssss is the user?s configuration setting for the measure - ment provided via the interface. the format and pur - pose of these configuration bits mus t be according to the definitions for sm _ c onfig and valid for temp erature measurement in this case (bits [15:1 2 ] will be ignored). 1) recommended for raw data collection during calibration coefficient determination using the measurement setups pre - programmed in mtp . 2) recommended for raw data collection during calibration coefficient determination using un - programmed (not in mtp), external measurement setups ; e.g. , for evaluation purposes .
zssc3218 datasheet ? 2016 integrated device technology, inc. 27 april 20, 2016 3.5. communication interface 3.5.1. common f unctionality commands are handled by the command interpreter in the lv section . commands that need additional data are not treated differently than other commands because the hv interface is able to buffer the command and all the data that belongs to the command and the command interpreter is activated as soon as a command byte is received . every response starts with a status byte followed by the data word. the data word d epends on the previous command. it is possible to read the same data more than once if the read request is r epeated (i 2 c ? ) or a nop command is se nt (spi). if the next command is not a read request (i2c ? ) or a nop (spi), it invalidates any previous data. the zssc3218 supports the parallel setup of two amplifier - adc - configurations using sm_config1 and sm_config2 . switching between the two setups can be done with the commands b0 hex and b1 hex . note that the respective activation command must always be sent prior to the measurement request . the status byte contains the following bits in the sequence shown in table 3 . 3 : ? power indication ( b it 6) : 1 if the device is powered (v dd b on ); 0 if not powered. this is needed for the spi m ode where the master reads all zeroes if the device is not powered or in power - on reset (por) . ? busy indication ( b it 5) : 1 if the device is busy, which indicates that the data for the last command is not available yet. no new commands are processed if the device is busy . note: the device is always busy if cyclic measurement operation has been set up and started. ? currently active zssc3218 mode ( b its [ 4:3 ] ) : 00 = normal mode; 01 = command mode ; 1 x = idt r eserved . ? memory integrity/error flag ( b it 2) : 0 if integrity test passed ; 1 if test fai led. this bit indicates whether the checksum - based integrity check passed or failed. the memory error status bit is calculated only during the power - up sequence , so a newly written crc will only be used for memory verification and status update after a subsequent zssc3218 power - on reset (por) or reset by means of the res pin . ? config setup (bit 1): this bit i ndicates which sm_config register is being used for the active configuration: sm_config1 (12 hex ) or sm_config2 (16 hex ) . t he two alternate configurati on setup s allow for two different configurations of the external sen s or channel in order to support up to two application scenarios w ith the use of only one sensor - zssc3218 pair. this bit is 0 if sm_config1 was selected (default) . this bit is 1 if sm_confi g2 was selected. ? alu saturation ( b it 0 ) : if the last command was a measurement request , this bit is 0 if any intermediate value and the final ssc result are in a valid range and no ssc - calculation i nternal saturation occurred in the arithmetic logic unit (alu) . if the last command was a measurement request , this bit is 1 if an ssc - calculation internal saturation occurred . this bit is also 0 for any non - measurement command. table 3 . 3 general status byte bit 7 6 5 4 3 2 1 0 meaning 0 powered ? busy ? mode memory e rror ? config setup alu saturation
zssc3218 datasheet ? 2016 integrated device technology, inc. 28 april 20, 2016 table 3 . 4 mode status status[4:3] mode 00 normal m o de (sleep and cyclic operations) 01 command mode 10 idt r eserved 11 idt reserved further status information can be provided by the eoc pin. the eoc pin is set high when a measurement and calculation have been completed ( if no interrupt threshold is used, i.e. int_setup==00 bin ; see section 3.3 ) . 3.5.2. spi the spi m ode is available if the very first interface activity after zssc3218 power - up is an active signal at the ss pin . the pol arity and phase of the spi clock are programmable via the ckp_cke setting in bits [11:10] in address 02 hex as described in table 3 . 5 . ckp_cke is two bits: cpha (bit 10) , which selects which edge of sclk latches data, and cpol (bit 11) , which indicates whether sclk is high or low when it is idle. the polarity of the ss sign al and pin are programmable via the ss_polarity setting (bit 9). the different combinations of polarity and phase are illustrated in the figures below. figure 3 . 4 spi c onfiguration cpha=0 msb sclk ( cpol = 0 ) bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 lsb msb bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 lsb sclk ( cpol = 1 ) mosi miso / ss sample cpha = 0
zssc3218 datasheet ? 2016 integrated device technology, inc. 29 april 20, 2016 figure 3 . 5 spi configuration cpha=1 msb sclk (cpol=0) bit6 bit5 bit4 bit3 bit2 bit1 lsb msb bit6 bit5 bit4 bit3 bit2 bit1 lsb sclk (cpol=1) mosi miso /ss sample cpha=1 in spi mode , each command except nop is started as shown in figure 3 . 6 . after the execution of a command (busy = 0) , the expected data can be read as illustrated in figure 3 . 7 or if no data are returned by the command , the next command can be sent . the status can be read at any time with the nop command (see figure 3 . 8 ). figure 3 . 6 spi command request cmddat <15:8> cmddat <7:0> command other than nop status data data command request mosi miso note: a command request always consists of 3 bytes. if the command is shorter, then it must be completed with 0s . the data on miso depend on the preceding command.
zssc3218 datasheet ? 2016 integrated device technology, inc. 30 april 20, 2016 figure 3 . 7 spi read status command = nop status read status mosi miso figure 3 . 8 spi read data 3.5.3. i 2 c ? i 2 c ? m ode will be selected if the very first interface activity after zssc3218 power - up is an i 2 c ? command . in i 2 c ? m ode , each command is started as shown in f igure 3.8 . only the number of bytes that are needed for the command must be sen t . an exception is the hs - mode where 3 b ytes must always be sent as in spi m ode. after the execution of a command (busy = 0) , the expected data can be read as illustrated in figure 3 . 11 or if no data are returned by the command , the next command can be sen t . the status can be read at any time as described in figure 3 . 10 .
zssc3218 datasheet ? 2016 integrated device technology, inc. 31 april 20, 2016 figure 3 . 9 i 2 c ? command request s slaveaddr a 0 command a p s slaveaddr 0 a command a cmddat < 15 : 8 > a cmddat < 7 : 0 > a p command request ( i 2 c ? write ) write write from master to slave from slave to master s start condition p stop condition a n acknowledge not acknowledge figure 3 . 10 i 2 c ? read status s slaveaddr 1 a status n p read status ( i 2 c ? read ) read figure 3 . 11 i 2 c ? read data s slaveaddr 1 a status a memdat < 15 : 8 > a memdat < 7 : 0 > n p s slaveaddr 1 a status a sensordat < 15 : 8 > a sensordat < 7 : 0 > n p a tempdat < 15 : 8 > a tempdat < 7 : 0 > read data ( i 2 c ? read ) ( a ) example : after the completion of a memory read c ommand read ( b ) example : after the completion of a full measurement c ommand ( aa hex ) read sensordat < 23 : 16 > a a tempdat < 23 : 16 >
zssc3218 datasheet ? 2016 integrated device technology, inc. 32 april 20, 2016 all mandatory i2c ?- bus protocol features are implemented. optional features such as c lock s tretching, 10 - bit slave address, etc. , are not supported by the zssc3218 ?s interface. in i2c - high - speed mode, a command consists of a fixed length of three bytes. 3.6. multiple time programmable (mtp) memory in the zssc3218 , the memory is organized in 16 - bit wide registers and can be programmed multiple time s (ca. 1000) . there are 57 x 16- bit registers available for customer use. each register can be re - programmed. basically, t here are two mtp content sector s: ? customer use : accessible by mea ns of regular write operations: 40 hex to 79 hex . it cont ains the customer id , interface setup data, measurement setup information, calibration coefficients, etc. ? idt use : only accessible for write operations by idt . the idt sector contains specific trim information and is programmed during manufacturing test by idt . 3.6.1. programming memory programming memory is possible with any specified supply voltage level at vdd . the mtp programming voltage itself is generated by means of an int egrated charge pump , generating an internal memory programming voltage ; no additional, external voltage , other than vdd (as specified) is needed . a single 16 - bit register write will be completed within 16 ms after the respective programming command has been sent . after the memory is programmed , it must be read again to verify the validity of the memory content s .
zssc3218 datasheet ? 2016 integrated device technology, inc. 33 april 20, 2016 3.6.2. memory content s table 3 . 5 mtp memory content assignments mtp address word / bit range default setting description notes / explanations 00 hex 15:0 0000 hex cust_id0 customer id byte 0 (combines with m emory word 01 hex to form customer id) . 01 hex 15:0 0000 hex cust_id1 customer id byte 1 (combines with m emory word 0 0 hex to form customer id) . interface configuration 02 hex 6:0 000 0000 bin slave_addr i2c? slave address; valid range: 00 hex to 7f hex (default: 00 hex ). note : address codes 04 hex to 07 hex are reserved for entering the i 2 c? high speed mode . 8:7 00 bin int_setup interrupt configuration, eoc pin functionality: 00 en d -of - conversion s ignal 01 0 -1 trans ition if threshold1 (trsh1) is exceeded and 1 -0 transition if threshold1 is underrun again 10 0 -1 transition if threshold1 is underrun and 1 -0 tr ansition if threshold1 is exceeded again 11 eoc is determined by thres hold settings (see section 3.3): if (trsh1 > trsh2) then eoc/int (interrupt level) = 0 if (trsh1 > meas trsh2) where meas is the conditioned measure - ment result . o therwise eoc/int=1. if (trsh1 trsh2) then eoc = 1 if (trsh1 meas < trsh2) . o therwise eoc = 0. 9 0 bin ss_polarity determines the polarity of the slave select pin (ss) for spi operation: 0 ? slave select is active low (spi and zssc3218 are active if ss==0) 1 ? slave select is active high (spi and zssc3218 are active if ss==1)
zssc3218 datasheet ? 2016 integrated device technology, inc. 34 april 20, 2016 mtp address word / bit range default setting description notes / explanations 11:10 00 bin ckp_cke clock polarity and clock - edge select ? determines polarity and phase of spi interface clock with the following modes: 00 ? sclk is low in idle state, data latch with rising edge and data output with falling edge 01 ? sclk is low in idle state, data latch with falling edge and data output with rising edge 10 ? sclk is high in idle state, data latch with falling edge and data output with rising edge 11 ? sclk is high in idle state, data latch with rising edge and data output with falling edge 14:12 000 bin cyc_period update period ( zssc3218 sleep time, except oscillator) in cyclic operation: 000 ? not assigned 001 ? 125ms 010 ? 250ms 011 ? 500ms 100 ? 1000ms 101 ? 2000ms 110 ? 4000ms 111 ? not assigned 15 0 bin sot_curve type / shape of second - order curve correction for the sensor signal. 0 ? parabolic curve 1 ? s - shaped curve
zssc3218 datasheet ? 2016 integrated device technology, inc. 35 april 20, 2016 mtp address word / bit range default setting description notes / explanations signal conditioning parameter s 03 hex 15:0 0000 hex offset_ s [15:0] b its [15:0] of the 24 - bit - wide sensor offset correction coefficient offset_s . (t he msb s of th is coefficient including sign are offset_ s [23:16] , which is bits [15:8] in 0d hex .) 04 hex 15:0 0000 hex gain_ s [15:0] bits [15:0] of the 24 - bit - wide value of the sensor gain coefficient gain_s . (the msb s of this coefficient including sign are gain_ s [23:16] , which is bits [7:0] in 0d hex .) 05 hex 15:0 0000 hex tcg[15:0] bits [15:0] of the 24 - bit - wide coefficient tcg for the temperature correction of the sensor gain . (the msb s of this coefficient including sign are tcg[23: 16 ] , which is bits [15:8] in 0e hex .) 06 hex 15:0 0000 hex tco[15:0] bits [15:0] of the 24 - bit - wide c oefficient tco for temperature correction of the sensor offset . (the msbs of this coefficient including sign are tco[23:16] , which is bits [7:0] in 0e hex .) 07 hex 15:0 0000 hex sot_tco[15:0] bits [15:0] of the 24 - bit - wide 2 nd order term sot_tco applied to tco . (the msbs of this term including sign are sot_tco[23:16], which is bits[15:8] in 0f hex .) 08 hex 15:0 0000 hex sot_tcg[15:0] bits [15:0] of the 24 - bit - wide 2 nd order term sot_tcg applied to tcg . (the msbs of th is term including sign are sot_tcg[23:16], which is bits[7:0] in 0f hex .) 09 hex 15:0 0000 hex sot_ sens [15:0] bits [15:0] of the 24 - bit - wide 2 nd order term sot_sens applied to the sensor readout . (the msbs of this term including sign are sot_sens[23:16], which is bits[15:8] in 10 hex .) 0a hex 15:0 0000 hex offset_t[15:0] bits [15:0] of the 24 - bit - wide t emperature offset correction coefficient offset_t . (the msbs of this coefficient including sign are offset_t[23:16], which is bits[7:0] in 10 hex .) 0b hex 15:0 0000 hex gain_t[15:0] bits [15:0] of the 24 - bit - wide a bsolute value of the temperature gain coefficient gain_t . (the msbs of this coefficient including sign are gain_t[23:16], which is bits[15:8] in 11 hex .) 0c hex 15:0 0000 hex sot_t[15:0] bits [15:0] of the 24 - bit - wide 2 nd - order term sot_t applied to the temperature reading . (the msbs of this coefficient including sign are sot_t[23:16], which is bit[7:0] in 11 hex .)
zssc3218 datasheet ? 2016 integrated device technology, inc. 36 april 20, 2016 mtp address word / bit range default setting description notes / explanations 0d hex 7:0 00 hex gain_s[23:16] bits [23:16] including sign for the 24 - bit - wide sensor gain correction coefficient gain_s. (the lsbs of this coefficient are gain_s[15:0] in register 04 hex .) 15:8 00 hex offset_s[23:16] bits [23:16] including sign for the 24 - bit - wide sensor offset correction coefficient offset_s. (the lsbs a re offset_s[15:0] in register 03 hex .) 0e hex 7:0 00 hex tco[23:16] bits [23:16] including sign for the 24 - bit - wide coefficient tco for temperature correction for the sensor offset . (the l sbs are tco[15:0] in register 06 hex .) 15:8 00 hex tcg[23:16] bi ts [23:16] including sign for the 24 - bit - wide coefficient tcg for the temperature correction of the sensor gain. (the lsbs are tcg[15:0] in register 05 hex .) 0f hex 7:0 00 hex sot_tcg[23:16] b its [23:16] including sign for the 24 - bit - wide 2 nd order term sot_tcg applied to tcg . (the lsbs are sot_tcg[15:0] in register 08 hex .) 15:8 00 hex sot_tco[23:16] bits [23:16] including sign for the 24 - bit - wide 2 nd order term sot_tco applied to tco . (the lsbs are sot_tco[15:0] in register 07 hex .) 10 hex 7:0 00 hex offset_t[23:16] bits [23:16] including sign for the 24 - bit - wide t emperature offset correction coefficient offset_t. (the lsbs a re offset_t[15:0] in register 0a hex .) 15:8 00 hex sot_sens[23:16] bits [23:16] including sign for the 24 - bit - wide 2 nd order term sot_sens applied to the sensor readout. (the lsbs are sot_sens[15:0] in register 09 hex .) 11 hex 7:0 00 hex sot_t[23:16] bits [23:16] including sign for the 24 - bit - wide 2 nd - order term sot_t applied to the temperature reading. (the lsbs are sot_t[15:0] in register 0c hex .) 15:8 00 hex gain_t[23:16] bits [23:16] including sign for the 24 - bit - wide absolute value of the temperature gain coefficient gain_t. (the lsbs are gain_t[15:0] in register 0b hex .)
zssc3218 datasheet ? 2016 integrated device technology, inc. 37 april 20, 2016 mtp address word / bit range default setting description notes / explanations measurement configuration register 1 ( sm_config 1 ) 12 hex 2:0 000 bin gain_stage1 gain setting for the 1 st prea mp stage with gain_stage1 ? gain amp1 : 000 ? 6 001 ? 12 010 ? 20 011 ? 30 100 ? 40 101 ? 60 110 ? 80 1 11 ? 120 ( might affect noise and accuracy specifications depending on sensor setup ) 5:3 000 bin gain_stage2 gain setting for the 2 nd preamp stage with gain_stage2 ? gain amp2 : 000 ? 1.1 001 ? 1.2 010 ? 1.3 011 ? 1.4 100 ? 1.5 101 ? 1.6 110 ? 1.7 111 ? 1.8 6 0 bin gain_polarity set up the polarity of the sensor bridge?s gain (inverting of the chopper) with 0 ? positive (no polarity change) 1 ? negative (180 polarity change) 10:7 0000 bin adc_bits absolute number of bits for the adc conversion adc_bits: 0000 ? 12 - bit 0001 ? 13 - bit 0010 ? 14 - bit 0011 ? 15 - bit 0100 ? 16 - bit 0101 ? 17 - bit 0110 ? 18 - bit 0111 to 1111 ? not assigned 11 0 bin absv_enable enable bit for thermopile input selection (inn connected to agnd, inp connected to absolute voltage source) with absv_enable: 0 ? absolute voltage input disabled (default) 1 ? absolute volt age input enabled (e.g. for a thermopile)
zssc3218 datasheet ? 2016 integrated device technology, inc. 38 april 20, 2016 mtp address word / bit range default setting description notes / explanations 14:12 000 bin offset differential signal?s offset shift in the adc; compensation of signal offset by x% of input signal : 000 ? no offset compensation 001 ? 6.75% offset 010 ? 12.5% offset 011 ? 19.25% offset 100 ? 25% offset 101 ? 31.75% offset 110 ? 38.5% offset 111 ? 43.25% offset note: bit 15 below must be set to 1 to enable the offset shift. 15 0 bin shift_method offset s hift m ethod switch: 0 ? no o ffset s hift . offset (bits [14:12] in 12 hex ) must be set to 000 bin ; gain adc = 1 1 ? offset s hift adc ; gain adc = 2 13 hex 15:0 0000 hex trsh1[15:0] bits [15:0] of the 24 - bit - wide interrupt threshold 1, trsh1 . (the msb bits for this threshold are trsh1[23:16], which is bits [7:0] of register 15 hex .) 14 hex 15:0 0000 hex trsh2[15:0] bits [15:0] of the 24 - bit - wide interrupt threshold 2, trsh2 . (the msb bits for this threshold are trsh2[23:16], which is bits[15:8] of register 15 hex .) 15 hex 7:0 00 hex trsh1[23:16] bits [23:16] of the 24- bit - wide interrupt threshold 1, trsh1 . (the lsb bits for this threshold are trsh1[15:0], which is bits[15:0] of register 13 hex .) 15:8 00 hex trsh2[23:16] bits [23:16] of the 24- bit - wide interrupt threshold 2, trsh2 . (the lsb bits for this threshold are trsh2[15:0], which is bits[15:0] of register 14 hex .) measurement configuration register 2 ( sm_config2 ) 16 hex 2:0 000 bin gain_stage1 gain setting for the 1 st preamp stage with gain_stage1 ? gain amp1 : 000 ? 6 001 ? 12 010 ? 20 011 ? 30 100 ? 40 101 ? 60 110 ? 80 1 11 ? 120 (might affect noise and accuracy specifications depending on sensor setup )
zssc3218 datasheet ? 2016 integrated device technology, inc. 39 april 20, 2016 mtp address word / bit range default setting description notes / explanations 5:3 000 bin gain_stage2 gain setting for the 2 nd preamp stage with gain_stage2 ? gain amp2 : 000 ? 1.1 001 ? 1.2 010 ? 1.3 011 ? 1.4 100 ? 1.5 101 ? 1.6 110 ? 1.7 111 ? 1.8 6 0 bin gain_polarity set up the polarity of the sensor bridge?s gain (inverting of the chopper) with 0 ? positive (no polarity change) 1 ? negative (180 polarity change) 10:7 0000 bin adc_bits absolute number of bits for the adc conversion adc_bits: 0000 ? 12 - bit 0001 ? 13 - bit 0010 ? 14 - bit 0011 ? 15 - bit 0100 ? 16 - bit 0101 ? 17 - bit 0110 ? 18 - bit 0111 to 1111 ? not assigned 11 0 bin absv_enable enable bit for thermopile input selection (inn connected to agnd, inp connected to absolute voltage source) with absv_enable: 0 ? absolute voltage input disabled (default) 1 ? absolute volt age input enabled (e.g. for a thermopile) 14:12 000 bin offset differential signal?s offset shift in the adc; compensation of signal offset by x% of input signal : 000 ? no offset compensation 001 ? 6.75% offset 010 ? 12.5% offset 011 ? 19.25% offset 100 ? 25% offset 101 ? 31.75% offset 110 ? 38.5% offset 111 ? 43.25% offset note: bit 15 below must be set to 1 to enable the offset shift.
zssc3218 datasheet ? 2016 integrated device technology, inc. 40 april 20, 2016 mtp address word / bit range default setting description notes / explanations 15 0 bin shift_method offset shift method switch: 0 ? no offset shift. offset (bits[14:12] in 16 hex ) must be set to 000 bin ; gain adc = 1 1 ? offset shift adc, gain adc = 2 post - calibration offset correction coefficients 17 hex 15:0 0000 hex sens _shift[15:0] bits [15:0] of the post - calibration sensor offset shift coefficient sens_shift . (the msb bits of sens_shift are bits [7:0] of register 19 hex .) 18 hex 15:0 0000 hex t_shift[15:0] bits [15:0] of the post - calibration temperature offset shift coefficient t_shift. (the msb bits of t_shift are bits [15:8] of register 19 hex .) 19 hex 7:0 00 hex sens _shift[23:16] bits [23:16] of the post - calibration sensor offset shift coefficient sens_shift. (the lsb bits of sens_shift are in register 1 7 hex .) 15:8 00 hex t_shift[23:16] bits [23:16] of the post - calibration temperature offset shift coefficient t_shift. (the l sb bits of t_shift are in register 1 8 hex .) free memory ? arbitrary use 20 hex 15:0 0000 hex not assigned (e.g., can be used for cust_i d x customer identification number) 21 hex 15:0 0000 hex not assigned (e.g., can be used for cust_i d x customer identification number) ? not assigned (e.g., can be used for cust_i d x customer identification number) 37 hex 15:0 0000 hex not assigned (e.g., can be used for cust_i d x customer identification number) 38 hex 15:0 0000 hex not assigned (e.g., can be used for cust_i d x customer identification number) 39 hex 15:0 - checksum generated (checksum) for the entire memory through a linear feedback shift register (lfsr); sig - nature is checked on power - up to ensure memory content integrity the memory integrity checksum ( referred to as crc) is generated through a linear feedback shift register with the following polynomial: g(x) = x 16 + x 15 + x 2 + 1 with the initial ization value : ffff hex . if the crc is valid, then the ? memory error? status bit is set to 0.
zssc3218 datasheet ? 2016 integrated device technology, inc. 41 april 20, 2016 3.7. calibration sequence calibration essentially involves collecting raw signal and temperature data from the s ensor - zssc3218 system for different known sensor - element values (i.e., for a resistive bridge or an absolute voltage source) and tempera - tures. this raw data can then be processed by the calibration master (assumed to be the user?s computer ), and the calculated calibration coefficients can then be written to on- chip memory. here is a brief overview of the three main steps involved in calibrating the zssc3218 . 1. assigning a unique identification to the zssc3218 . this identification is written to s hadow ram and programmed in mtp memory. this unique identification ca n be stored in the two 16 - bit registers dedicated to the customer id. it can be used as an index into a database stored on the calibration pc. this database will contain all the raw values of the connected sensor - element readings and temperature readings f or that part, as well as the known sensor - element measurand conditions and temperature to which the sensor - element was exposed. 2. data collection. data collection involves getting uncorrected ( raw ) data from the external sensor at different known measurand values and temperatures. then this data is stored on the calibration master using the unique identification of the device as the index to the database. 3. coefficient calculation and storage in mtp memory. after enough data points have been collected to calcu late all the desired coefficients, the coefficients can be c alculated by the calibrati on master . then the coefficients can be programmed to the mtp memory. result . t he sensor signal and the characteristic temperature effect on output will be linearized according to the setup - dependent maximum output range. it is essential to perform the calibration with a fixed programming setup during the data collection phase. in order to prevent any accidental misprocessing, it is further recommen ded to keep the mtp memory setup stable during the entire calibration process as well as in the subsequent operation. a zssc3218 calibration only fits the setup used during its calibration . changes of functional parameters after a successful calibration ca n decrease the precision and accuracy performance of the zssc3218 as well as of the entire application. the zssc3218 supports operation with different sensor setups by means of the sm_config1 and sm_config2 registers. however, only one calibration coeffic ient set is supported. therefore , either an alternative zssc3218 - external signal calibration using the alternate sm_config settings must be performed to ensure that the pro - grammed ssc coefficients are valid for both setups, or a full reprogramming of the ssc coefficients must be performed each time the sensor setup is changed. the selection of the external sensor setup (i.e. , the afe configuration) can be done with the interface commands b0 hex and b1 hex . 3.7.1. calibration step 1 ? assigning unique identification assign a unique identification number to the zssc3218 by using the memory write command (40 hex + data and 41 hex + data; see table 3 . 1 and table 3 . 5 ) to write the identification number to cust_id0 at memory address 00 hex and cust_id1 at address 01 hex as described in section 3.6.1 . these two 16 - bit registers allow for more than 4 billion unique devices.
zssc3218 datasheet ? 2016 integrated device technology, inc. 42 april 20, 2016 3.7.2. calibration step 2 ? data collection the number of unique points ( measurand and/or temperatur e) at which calibration must be performed generally depends on the requirements of the application and the behavior of the sensor in use. the minimum number of points required is equal to the number of correction coefficients to be corrected with a minimum of three different temperatures at three different sensor values . for a full calibration resulting in values for all 7 possible (external) sensor coefficients and 3 possible temperature coefficients, a minimum of 7 pairs of sensor with temp erature measurements must be collected. within this minimum field of 3 measurand measurements x 3 temperature measurements, data must be collected for the specific value pairs (at known conditions) and then processed to calculate the coefficients . in order to obtain the potentially best and most robust coefficients, it is recommended that measurement pairs (temperature vs. measurand ) be collected at the outer corners of the intended operation range or at least at points that are located far from each other. it is also essential to provide highly precise reference values as nominal, expected values. the measurement precision of the external calibration - measurement equipment should be ten times more accurate than the expected zssc3218 output accuracy after cal ibration in order to avoid accuracy losses caused by the nominal reference values (e.g. , measurand signal and temperature deviations). note: the coefficients sens_shift and t_shift must not be determined during this calibration step. these coeffi - cients can be pre - determined as zero until after initial calibration. note : an appropriate selection of measurement pairs can significantly improve the overall system performance. the determination of the measurand - related coefficients will use all of the measure ment pairs. for the temperature - related correction coefficients, 3 (at three different temperatures) of the measurement pairs will be used. note : there is an inherent redundancy in the 7 sensor - related and 3 temperature - related coefficients. since the temp erature is a necessary output (which also needs correction), the temperature - related information is mathematically separated, which supports faster and more efficient dsp calculations during the normal usage of the sensor - zssc3218 system. the recommended a pproach for data collection is to make use of the raw - measurement commands described in table 3 . 2 . f or external sensor values , either of the following commands can be used depending on the user?s require - ments : ? a 2 hex + 0000 hex single sensor measurement for which the configuration register will be loaded from the sm _config 1 register (1 2 hex in mtp); p reprogramming the measurement setup in the mtp is req uired. ? a3 hex + ssss hex single sensor measurement for which the sm _ c onfig c onfiguration register (gain, adc, offset, etc.) will be loaded as the user?s configuration ssss hex , which must be provided externally via the interface as the data part of this command . f or temperature values , either of the following commands can be used depending on the user?s require - ments: ? a6 hex + 0000 hex single temperature measurement for which the configuration register will be loaded from an inter nal temperature configuration register (preprogrammed by idt in the mtp ); preprogramming of the respective configuration is done by idt prior to zssc3218 delivery . this is the recommended a pproach for temperature data collection.
zssc3218 datasheet ? 2016 integrated device technology, inc. 43 april 20, 2016 ? a7 hex + ssss hex single te mperature measurement for which the configuration registe r (gain, adc, offset, etc.) will be loaded as the user?s configuration ssss hex , which must be provided externally via the interface as the data part of this command . the format and purpose o f these configuration bits must be according to the definitions for sm_config and valid for temperature measurement in this case (bits [15:1 2 ] will be ignored). 3.7.3. calibration step 3 a) ? coefficient calculations the math to perform the coefficient calculation is complicated and will not be discussed in detail. there is a brief overview in the next section. idt provide s software (dlls) to perform the coefficient calculation (external to the s ensor - zssc3218 system) based on auto - zero corrected v alues. after the coefficients are calculated, the final step is to write them to the mtp memory of the zssc3218 . 3.7.4. calibration step 3b) ? post - calibration offset correction there are two special ssc coefficients, sens_shift and t_shift . normally, t hese coefficients must be predeter - mined as zero during the initial sensor calibration. the primary purpose of these two coefficients is to cancel additional offset shifts that could occur during or after final sensor assembly ; e.g. if a respective sensor is finally place d and s oldered on a n application board . if the final sensor assembly induced any kind of offset ( on either the temperature or external sensor signal), the respective influence can be directly compensated by means of the sens_shift and t_shift coefficients without the need to change the original ssc coefficient set. however, this post - calibration offset correction must be done under known ambient conditions (i.e. , sensor measurand and/or temperature). 3.7.5. ssc measurements after the completion of th e calibration procedure, linearized external sensor and temperature readings can be obtained using the commands aa hex to af hex as described in table 3 . 1 . typically, only one external sensor is used in a single analog configuration using the setup in the sm_config1 mtp register ( 12 hex ). however, the zssc3218 can support a second analog configuration that is set up in the sm_config2 mtp register ( 16 hex ) . this m ight be useful in cases where only one sensor - zssc3218 pair must support the measurand ranges for two different external sensors that have different precisions, required amplification, and sensor offset . if a respective switching between setups is to be performed, the ssc c oeffi cients for the alternate external sensor must be handled with one of the following methods: ? the programmed ssc coefficients are not used for the alternate external sensor. the zssc3218 per form s only a factor - one transfer, i .e. no effective digital ssc correction ? only a transfer of the auto - zero corrected raw adc readings to the zssc3218 output without any scaling, etc. ? the coefficients are re - programmed each time the analog setup is changed. sm_config1 is selected as the a nalog setup register by default , so no specific activation is needed if only sm_config1 is used. if sm_config2 will also be used, the activation command b1 hex must be sent once p rior to the measurement request . to switch to using sm_config1 , the activation command b0 hex must be sent prior to use . this respective activation must be refreshed after any power - on- reset o r res pin reset.
zssc3218 datasheet ? 2016 integrated device technology, inc. 44 april 20, 2016 3.8. the calibration math 3.8.1. bridge signal compensation the saturation check in the zssc3218 detects saturation effects of the internal calculation steps, allowing the final correction output to be determined despite the saturation . it is possible to get potentially useful signal conditioning results that have had an intermediate saturation during the cal culations . t hese cases are detectable by observing the status bit[0] for each measurement result. details about the saturation limits and the valid ranges for values are provided in the following equations. the calibration math description assumes a calcul ation with integer numbers. the description is numerically correct concerning values, dynamic range , and resolution. sot_curve selects whether second - order equations compensate for sensor nonlinearity with a parabolic or s - shaped curve. the parabolic compe nsation is recommended for most sensor types . for the following equations, the terms are as follows: s = corrected sensor reading output via i 2 c? or spi; range [0 hex to ffffff hex ] s_raw = raw sensor reading from adc after az correction; range [ - 0x7ffff, 0x7ffff ] gain _s = sensor gain term; range [ - 0x7ffff, 0x7ffff ] offset _s = sensor offset term; range [ - 0x7ffff, 0x7ffff ] tcg = temperature coefficient gain term; range [ - 0x7ffff, 0x7ffff ] tco = temperature coefficient offset term; range [ - 0x7ffff, 0x7ffff ] t_raw = raw temperature reading after az correction; range [ - 0x7ffff, 0x7ffff ] sot _tcg = second - order term for tcg non - linearity; range [ - 0x7ffff, 0x7ffff ] sot _tco = second - order term for tco non - linearity; range [ - 0x7ffff, 0x7ffff ] sot_sens = second - orde r term for sensor non - linearity; range [ - 0x7ffff, 0x7ffff ] sens_shift = post - calibration, post - assembly sensor offset shift; range [ - 0x7ffff, 0x7ffff] ? = absolute value [ ] ul ll ? = bound/saturation number range from ll to ul , over/under - flow is reported as saturation in the status byte
zssc3218 datasheet ? 2016 integrated device technology, inc. 45 april 20, 2016 the correction formula for the differential signal reading is represented as a two - step process depending on the sot_curve setting. equations for the parabolic sot_curve setting ( sot_cu rve = 0): simplified: ? ? ? ? ? ? ? + ? ? ? + = tcg raw t tcg sot raw t k 4 _ 2 _ 4 2 _ 2 23 23 23 1 (1) ? ? ? ? ? ? ? + ? ? ? + + ? = tco raw t tco sot raw t raw s s offset k 4 _ 2 _ 4 2 _ _ _ 4 23 23 2 (2) 23 2 23 1 23 2 2 2 _ 4 + ? ? ? = k k s gain z sp (delimited to positive number range) (3) shift sens z sens sot z s sp bp _ 2 2 _ 4 2 23 23 23 + ? ? ? ? ? ? + ? ? ? = (delimited to positive number range) (4)
zssc3218 datasheet ? 2016 integrated device technology, inc. 46 april 20, 2016 complete: 1 2 2 1 2 2 1 2 2 1 2 2 21 23 23 1 25 25 25 25 25 25 25 25 4 _ 2 _ 2 _ 2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? + = tcg raw t tcg sot raw t k (5) 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2 21 23 2 25 25 25 25 25 25 25 25 25 25 4 _ 2 _ 2 _ _ _ 4 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? + + ? = tco raw t tco sot raw t raw s s offset k (6) 1 2 0 23 1 2 2 1 2 2 2 23 1 21 25 25 25 25 25 2 2 2 _ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? = k k s gain z sp (7) 1 2 0 1 2 2 23 1 2 2 21 23 24 25 25 25 25 _ 2 2 _ 2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? = shift sens z sens sot z b bp sp (8) equations for the s - shaped sot_curve setting ( sot_curve = 1): simplified : 2 23 1 23 2 2 _ 4 k k s gain z ss ? ? ? = (9) shift sens z sens sot z s ss ss _ 2 2 2 _ 4 2 23 23 23 23 + + ? ? ? ? ? ? + ? ? ? = ( delimited to positive number range) (10) complete : 1 2 2 1 2 2 2 23 1 21 25 25 25 25 2 2 _ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? = k k s gain z ss (11) 1 2 0 23 1 2 2 1 2 2 23 1 2 2 21 23 24 25 25 25 25 25 25 _ 2 2 2 _ 2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? = shift sens z sens sot z s ss ss (12)
zssc3218 datasheet ? 2016 integrated device technology, inc. 47 april 20, 2016 3.8.2. temperature signal compensation temperature is measured internally. temperature correction contains bot h linear gain and offset terms as well as a second - order term to correct for any nonlinearities. for temperature, second - order compensation for nonlinearity is always parabolic. t he correction formula is best represented as a two - step process as follows: si mplified : ( ) 23 23 2 _ 4 _ 2 _ 4 + ? + ? ? = t offset raw t t gain z t (delimited to positive number range) (13) shift t z t sot z t t t _ 2 2 _ 4 2 23 23 23 + ? ? ? ? ? ? + ? ? ? = (delimited to positive number range) (14) complete : [ ] 1 2 0 23 1 2 2 1 2 2 21 25 25 25 25 25 2 _ 4 _ 2 _ ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? + ? = t offset raw t t gain z t (15) 1 2 0 1 2 2 23 1 2 2 21 23 24 25 25 25 25 _ 2 2 _ 2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? = shift t z t sot z t t t (16) where t = corrected temperature sensor reading output via i 2 c? or spi; range [0 hex to ffffff hex ] gain_t = gain coefficient for temperature; range [ - 7 f ff ff hex to 7 ff fff hex ] t_raw = raw temperature reading after az correction; range [ - 7 ff ff f hex to 7 ff fff hex ] offset_t = offset coefficient for temperature; range [ - 7 f ff ff hex to 7 f ff ff hex ] sot_t = second - order term for temperature source non - linearity; range [ - 7 f ff ff hex to 7 f ff ff hex ] t_shift = shift for post - calibration/post - assembly offset compensation; range [ - 7fffff hex to 7fffff hex ]
zssc3218 datasheet ? 2016 integrated device technology, inc. 48 april 20, 2016 3.8.3. measurement output data format the data format and bit assignment of the raw measurement and ssc - corrected outputs of the zssc3218 are defined in the following tables. any adc measurement and ssc calculation output is formatted as a 24 - bit wide data word, regardless o f the effect ive adc resolution used . the values are either in two ?s complement or sign - absolute format. table 3 . 6 measurement results of adc raw m easurement r equest (two? s complement) bit 23 22 21 20 ? 1 0 meaning, w eighting -2 0 2 - 1 2 - 2 2 - 3 ? 2 - 22 2 - 23 table 3 . 7 calibration c oeffici ents (factors and summands) in m emory (sign - magnitude) bit 23 22 21 20 ? 1 0 meaning, weighting 0=positive 1=negative 2 1 2 0 2 - 1 ? 2 - 20 2 - 21 table 3 . 8 output results from ssc - correction math or dsp ? s ensor and t emperature bit 23 22 21 20 ? 1 0 meaning, weighting 2 0 2 - 1 2 - 2 2 - 3 ? 2 - 22 2 - 23 table 3 . 9 interrupt thresholds trsh1 and trsh2 ? f ormat as for ssc - correction math o utput bit 23 22 21 20 ? 1 0 meaning, weighting 2 0 2 - 1 2 - 2 2 - 3 ? 2 - 22 2 - 23
zssc3218 datasheet ? 2016 integrated device technology, inc. 49 april 20, 2016 4 package information and p ad assignments t he zssc3218 is available in die form or as engineering samples in the pqfn24 package. s ee figure 4 . 1 for additional die dimensions . in figure 4 . 1 , t he outer dimensions shown are (minimum) estimations for a die after sawing with out remaining scribe - line silicon around the core die. th erefore , the effective outer dimensions m ight differ slightly. figure 4 . 1 zssc3218 pad placement vssb vdd inn vddb vss zmdi - test zmdi - test eoc res zmdi - test mosi / sda sclk / scl inp miso zmdi - test ss seal ring ic core zmdi - test
zssc3218 datasheet ? 2016 integrated device technology, inc. 50 april 20, 2016 table 4 . 1 pad assignments name direction type description vdd in supply ic positive supply voltage for the ic . vss in supply ground reference voltage signal . res in digital ic r eset ( low active, internal pull -up ). vddb out analog positive external bridge - sensor supply . inn in analog negative sensor signal (or sensor - ground for absolute voltage - sources sensors). eoc out digital end of conversion or interrupt output. miso out digital data output for spi. ss in digital slave select for spi. inp in analog positive sensor signal. vssb out analog negative external bridge - sensor supply (sensor ground). mosi/sda in/out digital data input for spi; data in/out for i2c ?. sclk/scl in digital clock input for i2c?/spi. zmdi - test - - do not connect to these pads. table 4 . 2 die connection and bond parameter parameter typ max description / notes au bond, pull - force - 8 g soft b onding recommended . cu bond, pull - force not specified strongly n ot recommended . contact push - force to pad 0.0 5g/ m 0.1 g/ m a pplied force during wafer sort and/or bond- wire connection . probing overdrive - 55 m u p to 4 touch downs at 85c maximum; c antilever probe . generally, it is strongly recommended that bond and connection experiments be conducted in order to determine a proper assembly setup (golden wire, time, power, bonding force, etc. by means of wire - pull test, ball - shear test, and others ) t hat does not lead to any ic and /or pad damages. higher bond pull - forces maybe possible depending directly on the bond tool and temperature.
zssc3218 datasheet ? 2016 integrated device technology, inc. 51 april 20, 2016 figure 4 . 2 general pqfn24 package dimensions table 4 . 3 physical package dimensions parameter / dimension min (mm) max (mm) a 0.80 0.90 a 1 0.00 0.05 b 0.18 0.30 e 0.5nom h d 3.90 4.10 h e 3.90 4.10 l 0.35 0.45
zssc3218 datasheet ? 2016 integrated device technology, inc. 52 april 20, 2016 table 4 . 4 pin assignments pqfn24 pin no. name 1) direction type description 1 zmdi - test - - d o not connect . 2 res in digital ic r eset (low active, internal pull - up) . 3 vddb out analog positive external bridge - sensor supply . 4 inn in analog negative sensor signal (or sensor ground for absolute voltage - source sensors) . 5 eoc out digital end of conversion or i nterrupt o utput . 6 miso out digital data output for spi . 7 zmdi - test - - d o not connect . 8 n.c. - - - 9 n.c. - - - 10 n.c. - - - 11 n.c. - - - 12 sclk/ scl in digital clock input for i2c?/spi . 13 mosi/ sda in/out digital data input for spi; data in/out for i2c? . 14 vssb out analog negative external bridge - sensor supply (sensor ground) . 15 inp in analog positive sensor signal . 16 zmdi - test - - d o not connect . 17 ss in digital slave select for spi 18 zmdi - test - - do not connect. 19 zmdi - test - - do not connect. 20 n.c. - - - 21 n.c. - - - 22 vdd in supply ic positive supply voltage for the zssc3218. 23 n.c. - - - 24 vss in supply ground reference voltage signal . 25 exposed pad - - d o not connect electrically . 1) n.c. stands for not connected / no connection required / not bonded.
zssc3218 datasheet ? 2016 integrated device technology, inc. 53 april 20, 2016 5 quality and reliability the zssc3218 is available as a qualified ic for consumer - market applications . a ll data specified parameters are guaranteed if not stated otherwise. 6 ordering sales codes sales code description package ZSSC3218BI1B die ? temperature range: ? 40c to +85 c , thickness 304 m unsawn wafer zssc3218bi2b die ? temperature range: ? 40c to +85 c, thickness 725 m (w/o ba c klapping) unsawn wafer zssc3218bi3r es pqfn24 ? temperature range: ? 40c to +85 c, engineering samples packaged die contact idt sales for additional information. 7 related documents document zssc3218 feature sheet visit the zssc3218 product page www.idt.com/zssc3218 or contact your nearest sales office for ordering information or the latest version of these documents.
zssc3218 datasheet ? 2016 integrated device technology, inc. 54 april 20, 2016 8 glossary term description a2d analog - to -d igital ack acknowledge ( interface?s protocol indicator for successful data/command transfer) adc analog - to - digital converter or c onversion alu arithmetic logic unit az auto - zero (unspecific) az sm auto - zero m easurement for (external) s ensor p ath azt m auto - zero measurement for t emperature p ath au gold clk clock cu c opper dac digital -to - analog conversion or c onverter df data fetch (command type) dsp digital signal processor eoc end of conversion fso full scale output ( value in percent relative to the adc maximum output code; resolution dependent) lsb least significant bit lfsr linear feedback shift register mr measurement request (command type) msb m ost significant bit mtp multiple - time programmable memory nack not acknowledge ( interface?s protocol indicator for unsuccessful data/command transfer) por power -on r eset preamp pre amplifier psrr power supply disturbance rejection ratio sm signal m easurement sot second -o rder t erm tc temperature c oefficient (of a resistor or the equivalent bridge resistance) tm temperature m easurement
zssc3218 datasheet ? 2016 integrated device technology, inc. 55 april 20, 2016 9 document revision history revision date description 1.00 august 21 , 2014 first release . 1.01 september 11, 2014 update for sleep state current on page 2. minor edits. 1.02 october 2, 2014 update of ssc -n oise values in table 2 . 6 . 1.03 november 1 7 , 2014 correction s in table 3 . 5 for settings for cyc_period , gain_stage1, gain_stage2, adc_bits and offset . correction for figure 2 . 3 . a pril 20 , 2016 changed to idt branding. corporate headquarters 6024 silver creek valley road san jose, ca 95138 www.idt.com sales 1- 800- 345- 7015 or 408 - 284- 8200 fax: 408 - 284- 2775 www.idt.com/go/sales tech support www.idt.com/go/support disclaimer integrated device technology, inc. (idt) reserves the right to modify the products and/or specifications described herein at any time, without notice, at idt's sole discretion. performance specifications and operating parameters of the described products are determined in a n independent state and are not guaranteed to perform the same way when installed in customer products. the information contained herein is provided without representation or warranty of any kind, whether express or implied, includin g, but not limited to, the suitability of idt's products for any particular purpose, an implied warranty of merchantability, or non - infringement of the intellectual property rights of others. this document is presented only as a guide and does not convey an y license under intell ectual property rights of idt or any third parties. idt's products are not intended for use in applications involving extreme environmental conditions or in life support systems or similar devices where the failure or malfunction of an idt product can be reasonably expected to significantly affect the health or safety of users. anyone using an idt product in such a manner does so at their own risk, absent an express, written agreement by idt. integrated device technology, idt and the idt logo are trademar ks or registered trademarks of idt and its subsidiaries in the united states and other countries. other trademarks used herei n are the property of idt or their respective third party owners. for datasheet type definitions and a glossary of common terms, vi sit www.idt.com/go/glossary . all contents of this document are copyright of integrated device technology, inc. all rights reserved.

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