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wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 1 SX9300 ultra low power, dual channel smart proximity sar compliant solution g eneral d escription the SX9300 is the worlds first dual channel capaci tive specific absorption rate (sar) controller that accura tely discriminates between an inanimate object and human body proximity. the resulting detection is used in portable electronic devices to reduce and control radio-freq uency (rf) emission power in the presence of a human body , enabling significant performance advantages for manufacturers of electronic devices with emf radiat ion sources to meet stringent emission regulations' cri teria and specific absorption rate (sar) standards. operating directly from an input supply voltage of 2.7 to 5.5 v, the SX9300 outputs its data via a 1.65 C 5.5v host compat ible i2c serial bus. the i2c serial communication bus port is compatible with 1.8v host control to report body detection/proximit y and to facilitate parameter settings adjustment. upon pro ximity detection, the nirq output asserts, enabling the us er to either determine the relative proximity distance, o r simply obtain an indication of detection. the serial bus can also serve to overwrite detection thresholds and operati onal settings in the event the user wants to change them from their factory presets. the SX9300 includes an on-chip auto-calibration con troller that regularly performs sensitivity adjustments to maintain peak performance over a wide variation of temperatu re, humidity and noise environments, providing simplifi ed product development and enhanced performance. a dedicated transmit enable (txen) pin is available to synchronize proximity measurements to rf transmissi on, enabling very low supply current and high noise imm unity by only measuring proximity when requested. k ey p roduct f eatures 2.7 C 5.5v input supply voltage dual sar capacitive sensor inputs on-chip sar engine for body versus inanimate objec t detection stable proximity sensing with temperature 20mm detection distance capacitance offset compensation to 30pf active sensor guarding automatic calibration ultra low power consumption: active mode: 170 ua doze mode: 18 ua sleep mode: 2.5 ua 400khz i2c serial interface four programmable i2c sub-addresses input levels compatible with 1.8v host processors open drain nirq interrupt pin three (3) reset sources: por, nrst pin, soft reset -40c to +85c operation compact size: 3 x 3mm thin qfn package pb & halogen free, rohs/weee compliant a pplications sar compliant systems notebooks tablets mobile phones mobile hot spots o rdering i nformation semtech p/n package marking SX9300iultrt note1 qfn-20 zm5c SX9300evk eval. kit note 1: quantities are ordered in 3k units per reel t ypical a pplication circuit
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 2 SX9300 ultra low power, dual channel smart proximity sar compliant solution table of contents g eneral d escription .................................................. ................................................... ................... 1 k ey p roduct f eatures ................................................... ................................................... ............... 1 a pplications .................................................. ................................................... .................................. 1 o rdering i nformation ................................................... ................................................... ................ 1 t ypical a pplication circuit .................................................. ................................................... ....... 1 1 g eneral d escription .................................................. ................................................... .......... 5 1.1 pin diagram 5 1.2 marking information 5 1.3 pin identification 6 1.4 acronyms 6 2 e lectrical c haracteristics .................................................. ............................................... 7 2.1 absolute maximum ratings 7 2.2 recommended operating conditions 7 2.3 thermal characteristics 7 3 f unctional description .................................................. ................................................... ... 11 3.1 introduction 11 3.1.1 general 11 3.1.2 parameters and configuration 11 3.1.3 sensor proximity adjustment 11 3.2 scan period 11 3.3 operational modes 12 3.4 i2c interface 12 3.5 configuration 13 3.6 reset 13 3.6.1 power-up 13 3.6.2 nrst 14 3.6.3 software reset 14 3.7 interrupt 15 3.7.1 power-up 15 3.7.2 nirq clearing 15 4 p in descriptions .................................................. ................................................... ................ 16 4.1 introduction 16 4.2 v dd and sv dd 16 4.3 txen 16 4.4 capacitor sensing interface (cs0a, cs0b, cs1a, cs1b , csg) 16 4.5 host interface 16 4.5.1 nirq 16 4.5.2 scl, nrst and txen 17 4.5.3 sda 17 5 d ifferential detection and sar compliance .................................................. ................ 18 5.1 specific absorption rate (sar) basics 18 5.2 sar solution 18 5.2.1 set cps_deb [5:4] (debounce) 18 5.2.2 set cps_deltatrs [3:0] (sar delta detection thresh old) 18 5.2.3 set cps_ratiotrs [7:0] (sar ratio detection thresh old) 19 5.2.4 setting up the SX9300 to discriminate between a hum an body & inanimate object 19
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 3 SX9300 ultra low power, dual channel smart proximity sar compliant solution 6 d etailed c onfiguration descriptions .................................................. ............................ 20 6.1 introduction 20 6.2 capacitive sensor (cs0a, cs0b, cs1a, cs1b) paramete rs 20 6.2.1 set cps_digital_gain [6:5] (cap sensor gain) 20 6.2.2 set cps_c in r [1:0] (input capacitance range and resolution) 20 6.2.3 set cps_trs [4:0] (detection threshold) 21 6.2.4 set cps_hyst [5:4] (detection hysteresis) 22 6.2.5 set cps_avgdeb[7:6] (average pos/neg debouncing) 22 6.2.6 set cps_avgnegfilt[5:3] & cps_avgposfilt[2:0] (aver age neg/pos filters) 22 6.2.7 set cps_fs[4:3] (sampling frequency) 23 6.2.8 set cps_res[2:0] (resolution factor) 23 6.2.9 set cps_avgtrs[7:0] (averaging threshold) 23 6.3 additional parameter settings 24 6.3.1 set cps_period[6:4] (scan period) 24 6.3.2 set cps_en [3:0] (enable capacitive sensor inputs) 24 6.3.3 set irq_enable [6:3] (enable interrupt sources) 24 7 i2c i nterface .................................................. ................................................... ...................... 25 7.1 i2c write 25 7.2 i2c read 26 7.3 register overview 27 7.4 sar sensor design 31 8 p ackaging i nformation .................................................. ................................................... ... 32 8.1 package outline drawing 32 8.2 land pattern 33 list of figures figure 1: pin diagram .................................................. ................................................... ........................................ 5 figure 2: qfn marking information .................................................. ................................................... .................. 5 figure 3: i2c start and stop timing .................................................. ................................................... ................ 10 figure 4: i2c data timing .................................................. ................................................... ................................. 10 figure 5 scan period ................................................... ................................................... ....................................... 11 figure 6: power-up vs. nirq .................................................. ................................................... ........................... 13 figure 7: hardware reset .................................................. ................................................... ................................ 14 figure 8: software reset .................................................. ................................................... ................................. 14 figure 9: nirq output simplified diagram .................................................. ................................................... ... 16 figure 10: scl/txen/nrst .................................................. ................................................... ............................ 17 figure 11: sda simplified diagram .................................................. ................................................... ................ 17 figure 12: i2c write ................................................... ................................................... ......................................... 25 figure 13: i2c read .................................................. ................................................... .......................................... 26 figure 14: typical sar capacitive sensor .................................................. ................................................... .... 31 figure 15: package outline drawing .................................................. ................................................... .............. 32 figure 16: package land pattern .................................................. ................................................... ................... 33
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 4 SX9300 ultra low power, dual channel smart proximity sar compliant solution list of tables table 1: pin description .................................................. ................................................... .................................... 6 table 2: absolute maximum ratings .................................................. ................................................... ............... 7 table 3: recommended operating conditions .................................................. .................................................. 7 table 4: thermal characteristics .................................................. ................................................... ...................... 7 table 5: electrical characteristics .................................................. ................................................... .................... 9 table 6: i2c timing specification .................................................. ................................................... ................... 10 table 7: i2c sub-address selection ................................................... ................................................... .............. 12 table 8: detection debounce control .................................................. ................................................... ............ 18 table 9: delta threshold selection .................................................. ................................................... ................ 18 table 10: cps_digital_gain .................................................. ................................................... ........................... 20 table 11: c input range and resolution register .................................................. ............................................. 20 table 12: cap sensor threshold .................................................. ................................................... .................... 21 table 13: cps_hyst .................................................. ................................................... ........................................ 22 table 14: cps_avgdeb .................................................. ................................................... .................................. 22 table 15: sampling frequency control .................................................. ................................................... ......... 23 table 16: cps resolution factor .................................................. ................................................... .................... 23 table 17: scan period .................................................. ................................................... ...................................... 24 table 18: register overview .................................................. ................................................... ........................... 30
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 5 SX9300 ultra low power, dual channel smart proximity sar compliant solution 1 g eneral d escription 1.1 pin diagram figure 1: pin diagram 1.2 marking information zm5c yyww xxxx yyww= date code xxxx = lot number figure 2: qfn marking information
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 6 SX9300 ultra low power, dual channel smart proximity sar compliant solution 1.3 pin identification pin number name type description 1 csg analog capacitive sensor guard 2 cs1b analog capacitive sensor, 1b 3 cs1a analog capacitive sensor, 1a 4 cs0b analog capacitive sensor, 0b 5 cs0a analog capacitive sensor, 0a 6 gnd ground ground 7 nc not used do not connect 8 nc not used do not connect 9 nc not used do not connect 10 nc not used do not connect 11 v dd power SX9300 core power 12 sv dd power host serial port supply voltage. must be less than or equal to v dd . note: during power-up or power-down, sv dd must be less than or equal to v dd 13 nirq digital output interrupt request, active lo w, requires pull-up resistor to sv dd 14 scl digital input i2c clock, requires pull up res istor to sv dd 15 sda digital i/o i2c data, requires pull up resist or to sv dd 16 txen input transmit enable, active high (tie to sv dd if not used). 17 nrst input external reset, active low, requires p ull up resistor to sv dd 18 a1 digital input i2c sub-address, connect to gnd o r v dd 19 a0 digital input i2c sub-address, connect to gnd o r v dd 20 gnd ground ground dap gnd ground exposed pad. connect to ground table 1: pin description 1.4 acronyms dap die attach paddle sar specific absorption rate
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 7 SX9300 ultra low power, dual channel smart proximity sar compliant solution 2 e lectrical c haracteristics 2.1 absolute maximum ratings stresses above the values listed in absolute maxim um ratings may cause permanent damage to the devic e. this is a stress rating only and functional operation of the device at these, or any other conditions beyond the recommended opera ting conditions, is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability and proper functionality. parameter symbol min max unit supply voltage v dd -0.5 6.0 v sv dd -0.5 6.0 input voltage (non-supply pins) v in -0.5 v dd +0.3 input current (non-supply pins) i in -10 10 ma operating junction temperature t jct -40 125 c reflow temperature t re 260 storage temperature t stor -50 150 esd hbm (human body model, to jesd22-a114) esd hbm 8 kv table 2: absolute maximum ratings 2.2 recommended operating conditions parameter symbol min max unit supply voltage v dd 2.7 5.5 v sv dd 1.65 v dd ambient temperature range t a -40 85 c table 3: recommended operating conditions note: during power-up or power-down, sv dd must be less than or equal to v dd 2.3 thermal characteristics parameter symbol min typical max unit thermal resistance C junction to air (static airflow) q ja 34 c/w table 4: thermal characteristics note: theta ja is calculated from a package in stil l air, mounted to 3" x 4.5", 4 layer fr4 pcb with thermal vias under exposed pad per jesd51 standards .
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 8 SX9300 ultra low power, dual channel smart proximity sar compliant solution electrical specifications all values are valid within the operating condition s unless otherwise specified. parameter symbol conditions min typ max unit current consumption sleep mode i sleep power down, all a nalog circuits shut down. (i2c listening) 2.5 ua doze i doze cps_perio d = 2 00 ms dozeperiod = 2xcps_period cps_fs = 167khz cps_res = medium vdd = 5 volt 18 active (see note i) i active cps_period = 30ms cps_fs = 167khz cps_res = medium. vdd = 5 volt 170 outputs: sda, nirq output current at output low voltage i ol vol = 0.4v 6 ma maximum output low voltage v ol (max) sv dd > 2v 0.4 v sv dd 2v 0.2 x sv dd inputs: scl, sda, txen input logic high v ih 0.8 x sv dd sv dd + 0.3 v input logic low v il -0.3 0.25 x sv dd input leakage current i l cmos input -1 1 ua hysteresis v hys sv dd > 2v 0.05x sv dd v sv dd 2v 0.1x sv dd txen measurements txen actdly delay to when the SX9300 actually begins measurements from when txen becomes active 100 s input: a0, a1 input logic high v ih 0.7 x v dd v dd + 0.3 v input logic low v il -0.3 0.3 x v dd
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 9 SX9300 ultra low power, dual channel smart proximity sar compliant solution input: nrst input logic high v ih sv dd > 2v 0.7 x svdd sv dd + 0.3 v sv dd 2v 0.75 x svdd input logic low v il sv dd > 2v 0.6 sv dd 2v 0.3 x sv dd start-up power-up time t por 1 ms nrst nrst minimum pulse width t resetpw 20 ns table 5: electrical characteristics
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 10 SX9300 ultra low power, dual channel smart proximity sar compliant solution parameter symbol conditions min typ max unit i2c timing specifications scl clock frequency f scl 400 khz scl low period t low 1.3 us scl high period t high 0.6 data setup time t su;dat 100 data hold time t hd;dat 0 repeated start setup time t su;sta 0.6 start condition hold time t hd;sta 0.6 stop condition setup time t su;sto 0.6 bus free time between stop and start t buf 1.3 input glitch suppression t sp note (1) 50 ns note (1) -- minimum glitch amplitude is 0.7v dd at high level and maximum 0.3v dd at low level. table 6: i2c timing specification note: all timing specifications, refer to figure 3, figu re 4, and table 6 figure 3 : i2c start and stop timing figure 4: i2c data timing
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 11 SX9300 ultra low power, dual channel smart proximity sar compliant solution 3 f unctional description 3.1 introduction 3.1.1 general the SX9300 is the worlds first sar controller that is designed to detect proximity, differentiating b etween a human body and an inanimate object. the resulting detection is used in portable electronic devices to reduce and control radio-frequency (rf) emission power in the presence of a human body, enabling significant performance advantages for manufacturers of electro nic devices with emf radiation sources to meet stri ngent emission regulations' criteria and specific absorpt ion rate (sar) standards. 3.1.2 parameters and configuration the SX9300 allows the user full parameter customiza tion for sensor sensitivity, hysteresis, and detect ion thresholds. if custom parameters are used by the c ustomer, these parameters must be uploaded by the h ost immediately following boot-up or after a reset. 3.1.3 sensor proximity adjustment capacitive proximity detection is directly proporti onal to the SX9300 internal gain and threshold sett ings, and external sensor area to optimize proximity detectio n distance. a longer proximity detection range can be accomplished without changing the capacitive sensor size, by using a high sensitivity setting and/or l ower signal threshold setting for proximity detection. 3.2 scan period the scan period determines the minimum sar detectio n reaction time of the SX9300 and can be varied by the host from 30ms to approximately 400ms. sar detecti on reaction time is proportional to the scan period and inversely proportional to power consumption, so lon ger scan periods corresponds to lower power, but al so to longer detection reaction times. the scan period of the SX9300 is defined by two per iods: sensing and idle. during the sensing period, all enabled cs inputs, from cs0a to cs1b are sampled an d any detection reported via the i2c bus (via i2c r egister polling or nirq). the sensing period is variable a nd is proportional to the scan frequency and resolu tion settings in the cap sensing control registers. dur ing the idle period, the SX9300 the analog circuits are placed in standby and the idle timer is initiated. upon e xpiry of the idle timer, a new scan period cycle be gins. cs0a cs0b cs1b cs0a cs0b cs1a figure 5 scan period
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 12 SX9300 ultra low power, dual channel smart proximity sar compliant solution 3.3 operational modes the SX9300 has four (4) operational modes: active, doze, sleep, and commanded. these modes enable tradeoffs between sar detection reaction time and p ower consumption. active: active mode has the shortest scan periods, with a typical sar detection reaction time of 30ms. in th is mode, all enabled sensors are scanned and informati on data is processed within this interval. the act ive scan period is user configurable and can be extended to a maximum period of 400ms. see cps_period register in section 7.3, (i2c register overview) below. doze: doze mode is by default, enabled in the SX9300. the doze mode period is user configurable (see section 7.3, i2c register overview) and can be used to extend the scan period out to 6.4 seconds for v ery low power consumption applications at the expense of ve ry long sar detection reaction times (6.4 seconds). in some applications, the sar detection reaction ti me needs to be fast, when a human body is present, but can be slow when sar detection has not been active for a while. when the SX9300 has not detected an objec t for a specific time, it will automatically change modes f rom active to doze reducing power. this time-out p eriod is determined by the cps_dozeperiod which can be confi gured by the user or turned off (cps_dozeen) if not required. proximity detection on any sensor will cause the sx 9300 to leave doze mode and re-enter active mode. sleep: sleep mode places the SX9300 in its lowest power m ode, disabling all sensor scanning and setting the idle period to continuous. in this mode, only the i2c serial bus is active. commanded: the commanded mode is perhaps the SX9300s most us eful feature. the txen input enables the measurement of the sar channels when high, like wise when the txen input is low, the SX9300 is in t he sleep mode. specifically, on the rising edge of tx en the SX9300 will begin measuring the sar channels beginning with the lowest enabled channel repeating the measurement cycle at programmed rates (cps_period) so long as txen remains high. when tx en goes low the current measurement sequence will complete and then measurement will cease until the next rising edge of txen. 3.4 i2c interface the i2c serial interface is configured as a slave d evice, operates at speeds up to 400 khz and serves as the host interface to the SX9300. the SX9300 has two i/o pins (a0 and a1) that provid es for four possible, user selectable i2c addresses : table 7: i2c sub-address selection a1 a0 address 0 0 0x28 0 1 0x29 1 0 0x2a 1 1 0x2b
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 13 SX9300 ultra low power, dual channel smart proximity sar compliant solution 3.5 configuration if the application requires customization, the sx93 00 configuration registers can be changed over the i2c bus. some i2c addressable registers are used to read sen sor status and information, while other (configurat ion) registers allow the host to take control of the sx9 300. via the configuration registers, the host can command an operational mode change or modify the active sensor s. these user programmable configuration registers are volatile, therefore during a power-down or reset ev ent, they lose all user programmed content, requiri ng the host to re-write the i2c registers after the event. 3.6 reset a reset to the SX9300 is performed by any one of th e following methods: - power-up - nrst pin - software reset 3.6.1 power-up during a power-up condition, the nirq output is hig h until v dd has met the minimum input voltage requirements and a t por time has expired upon which, nirq asserts to a low condition indicating the SX9300 is initialized. the host is required to perform an i2c read to clea r this nirq status. the SX9300 is then ready for n ormal i2c communication and is operational. figure 6: power-up vs. nirq
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 14 SX9300 ultra low power, dual channel smart proximity sar compliant solution 3.6.2 nrst when nrst is asserted low and then high, the SX9300 will reset its internal registers and will become active after period, t por . if a hardware reset control output is not availa ble to drive nrst, then this pin must be pulled high to sv dd . figure 7: hardware reset 3.6.3 software reset the host can perform software resets by writing to the i2csoftreset register (see section 7.3 for addi tional information). the nirq output will be asserted low and the host is required to perform an i2c read to clear this nirq status. figure 8: software reset
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 15 SX9300 ultra low power, dual channel smart proximity sar compliant solution 3.7 interrupt interrupt sources are disabled by default upon powe r-up and resets, and thus must be enabled by the ho st (apart from reset irq). any or all of the following inter rupts can be enabled by writing a 1 into the appr opriate locations within the irq_enable register (see secti on 7.3 for details): body detected completed compensation completed conversion the interrupt status can be read from register irqs tat for each of these interrupt sources (see sectio n 7.3 for details). 3.7.1 power-up during initial power-up, the nirq output is high. once the SX9300 internal power-up sequence has comp leted, nirq is asserted low, signaling that the SX9300 is ready. the host must perform a read to irqstat to acknowledge that the status is read and the SX9300 will clear the interrupt and release the nirq line. 3.7.2 nirq clearing the nirq can be asserted in either the active or do ze mode during a scan period. the nirq will be automatically cleared after the host performs a rea d of the irqstat i2c register.
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 16 SX9300 ultra low power, dual channel smart proximity sar compliant solution 4 p in descriptions 4.1 introduction this section describes the SX9300 pin functionality , pin protection, whether or not the pins are analo g or digital, and if they require pull-up resistors. there is es d protection on all SX9300 i/o. 4.2 v dd and sv dd these are the device supply voltages. v dd is the supply voltage for the internal core and i/ o. sv dd is the supply voltage for the i2c serial interface. note: sv dd must be equal or lower than v dd . 4.3 txen this signal can be used in many applications if a c onversion trigger/enable is needed. this input pin synchronizes the capacitance sensing inputs in syst ems that need to (for example) transmit rf signals. when this signal is active, SX9300 immediately performs capacitive measurements. if this input becomes ina ctive during the middle of a measurement, the SX9300 will complete all remaining measurements and will enter sleep mode until txen goes active again. 4.4 capacitor sensing interface (cs0a, cs0b, cs1a, cs1b, csg) the capacitance sensor input pins cs0a, cs0b, cs1a and cs1b are connected directly to the capacitor sensing interface circuitry which converts the sens ed capacitance into digital values. the capacitive sensor guard (csg) output provides a guard reference to mi nimize the parasitic sensor pin capacitances to gro und. capacitance sensor pins which are not used must be left open-circuited. additionally, cs pins must be connected directly to the capacitive sensors using a minimum length circuit trace to minimize external noise pick-up. the capacitance sensor and capacitive sensor guard pins are protected from esd events to vdd and groun d. 4.5 host interface the host interface consists of: nirq, nrst, scl, sd a, and txen. these signals are discussed below. 4.5.1 nirq the nirq pin is an open drain output that requires an external pull-up resistor (1..10 kohm). the nir q pin is protected from esd events to svdd and ground. figure 9: nirq output simplified diagram svdd r_ int nirq SX9300 int nirq to host svd d
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 17 SX9300 ultra low power, dual channel smart proximity sar compliant solution 4.5.2 scl, nrst and txen the scl, nrst and txen pins are high impedance inpu t pins that require an external pull-up resistor (1 ..10 kohm). it is possible to connect nrst and txen hos t output drivers directly without the requirement f or a pull- up resistor if driven from a push-pull host output. these pins are protected from esd events to svdd and ground. figure 10: scl/txen/nrst 4.5.3 sda sda is an i/o pin that requires an external pull-up resistor (1..10 kohm). the sda i/o pin is protect ed to sv dd and ground. figure 11: sda simplified diagram svdd r s cl/txen/nrst from host scl_in/txen_in/nrst_in svdd svdd r_ sda sda sda_out to/from host sda_in svdd
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 18 SX9300 ultra low power, dual channel smart proximity sar compliant solution 5 d ifferential detection and sar compliance 5.1 specific absorption rate (sar) basics sar is a measure of the rate at which energy is abs orbed by the body when exposed to a radio frequency (rf) electromagnetic field; although, it can also refer to absorption of other forms of energy by tissue, i ncluding ultrasound. it is defined as the power absorbed pe r mass of tissue and has units of watts per kilogra m (w/kg). sar is usually averaged either over the whole body, or over a small sample volume (typically 1g or 10g of tissue). the value cited is then the maximum level measured in the body part studied over the stated volume or mass. the fcc requires that cell phone manufacturers cond uct their sar testing to include the most severe, worst- case (and highest power) operating conditions for a ll the frequency bands used in the usa for that cell phone. the sar values recorded on the fccs authorization and in the cell phone manual to demonstrate complia nce with commission rules indicate only the highest sin gle measurement taken for each frequency range that the particular model uses. fcc approval means that the device will never exceed the maximum levels of con sumer rf exposure permitted by federal guidelines, but it does not indicate the amount of rf exposure consum ers experience during normal use of the device. while only the maximum sar values are used for fcc approv al, all test reports submitted by the manufacturer are avai lable in full for public inspection on the commissions website. 5.2 sar solution a sar measurement consists of taking two sets of ca pacitive sensor data. in this case, each sensor mu st have recognized proximity detection. the two sets of da ta are then combined within the SX9300 as both a r atio of the data and a difference or delta of the data. the measured capacitance data can represent a very low level of capacitance. therefore insuring that the signal is detected for a number of samples will minimize false triggers. the SX9300 includes the ability to debo unce the detected data for up to 8 samples. 5.2.1 set cps_deb [5:4] (debounce) the register for the sar debounce control: bits [5: 4] set the number of debounce samples. bits 5 4 debounce samples 0 0 none 0 1 2 1 0 4 1 1 8 table 8: detection debounce control 5.2.2 set cps_deltatrs [3:0] (sar delta detection threshold) the register for the sar delta threshold control is at: bits [3:0] and is used to set delta detection threshold. the delta measurement is the capacitive difference measurement between the two sar sensing capacitors (sensor b C sensor a). reg value threshold value reg value threshold value 0000 0 1000 30 0001 1 1001 35 0010 3 1010 40 0011 5 1011 45 0100 10 1100 50 0101 15 1101 55 0110 20 1110 60 0111 25 1111 70 table 9: delta threshold selection
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 19 SX9300 ultra low power, dual channel smart proximity sar compliant solution 5.2.3 set cps_ratiotrs [7:0] (sar ratio detection threshold) the register for the sar ratio threshold control is at: 0x10. bits [7:0] are used to set the sar rati o threshold for the SX9300. the determination of the sar ratio detection threshold must be determined experimentally, but will be stable for a given desi gn 5.2.4 setting up the SX9300 to discriminate between a human body & inanimate object an accurate discrimination between a human body and inanimate object can be obtained using the SX9300. it is important that the sensor pair areas are identical (in area, not necessarily in shape, see section 7.4 for information as to how to design a successful sar ca pacitive sensor). this involves a careful set-up b etween the following two registers: delta and ratio thresholds . the set-up of these two registers is as follows: with the customers system set onto a table, bring a hand to the desired detection distance from the s ensor. set the delta threshold limit until a detection i s reported by the SX9300 set the ratio threshold limit until a detection i s reported by the SX9300 remove the hand and test with a number of inanimate objects to determine if the SX9300 successfully re jects them from reporting. if the SX9300 reports any of them as a detection, then raise the delta thresho ld limit until it stops being reported and confirm that the human body is still reported (note: you will lose a bit o f detection range when you raise threshold limits). if you cannot determine a successful setting that s imultaneously rejects inanimate objects and detects a human body, then you must raise the ratio threshold limit . repeat 4) until a solution is determined.
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 20 SX9300 ultra low power, dual channel smart proximity sar compliant solution 6 d etailed c onfiguration descriptions 6.1 introduction the SX9300 is the first smart proximity sar complia nt sensor that solves the human body versus inanima te object problem that designers of mobile appliances face every day. it requires only small external se nsors plus some minor set-up commands to provide a robust sar solution. the SX9300 comes with factory default se ttings that are appropriate for most general applications, however a full complement of registers are accessi ble to the user to enable application customization and optimi zation. 6.2 capacitive sensor (cs0a, cs0b, cs1a, cs1b) para meters the SX9300 sensor has default parameters for the ca pacitive sensors that provides a quick and initial starting point to achieve sar compliance. however, because of unique sensor sizes and sensor locations, it is possible to achieve higher and more robust performance with minor changes to these default parameters. in gene ral only a few registers require changes to their default pa rameters to achieve improved performance. these re gisters are: 6.2.1 set cps_digital_gain [6:5] (cap sensor gain) the address for the (capacitive) sensor gain is: b its [6:5] provide for four (4) gain settings as sho wn below: bits 6 5 gain 0 0 x 1 0 1 x 2 1 0 x 4 1 1 x 8 table 10: cps_digital_gain 6.2.2 set cps_c in r [1:0] (input capacitance range and resolution) the register for the input capacitance full scale r ange and resolution is: bits [1:0] provide set abi lity over the expected maximum sensed capacitance. a setting of 00 on these bits provides for the largest capacitan ce measurement range, but is not as sensitive for the longest proximity distance, while the setting of 11 provides for the smallest capacitive measurement range, and prov ides the longest proximity distance. the table for this register is shown below: bits 1 0 c input range and resolution 0 0 large 0 1 medium-large 1 0 medium-small 1 1 small table 11: c input range and resolution register
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 21 SX9300 ultra low power, dual channel smart proximity sar compliant solution 6.2.3 set cps_trs [4:0] ( detection threshold ) this register defines the detection threshold for a ll sensors and the details are shown below. lower thresholds provide longer proximity detection distances but ar e more susceptible to noise, while higher threshold values provide immunity to noise, but results in shorter p roximity detection range. the default value for th is register is [00000]. bits 4 3 2 1 0 threshold value 0 0 0 0 0 0 0 0 0 0 1 20 0 0 0 1 0 40 0 0 0 1 1 60 0 0 1 0 0 80 0 0 1 0 1 100 0 0 1 1 0 120 0 0 1 1 1 140 0 1 0 0 0 160 0 1 0 0 1 180 0 1 0 1 0 200 0 1 0 1 1 220 0 1 1 0 0 240 0 1 1 0 1 260 0 1 1 1 0 280 0 1 1 1 1 300 1 0 0 0 0 350 1 0 0 0 1 400 1 0 0 1 0 450 1 0 0 1 1 500 1 0 1 0 0 600 1 0 1 0 1 700 1 0 1 1 0 800 1 0 1 1 1 900 1 1 0 0 0 1000 1 1 0 0 1 1100 1 1 0 1 0 1200 1 1 0 1 1 1300 1 1 1 0 0 1400 1 1 1 0 1 1500 1 1 1 1 0 1600 1 1 1 1 1 1700 table 12: cap sensor threshold
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 22 SX9300 ultra low power, dual channel smart proximity sar compliant solution 6.2.4 set cps_hyst [5:4] (detection hysteresis) this register defines the detection hysteresis for all sensors. hysteresis for the sar sensors provid es an important function in that it keeps the SX9300 from providing oscillating results when detection lev els are close to threshold. the register details are shown below . bits 5 4 detection hysteresis 0 0 32 0 1 64 1 0 128 1 1 256 table 13: cps_hyst 6.2.5 set cps_avgdeb[7:6] (average pos/neg debounci ng) use of debounce in the SX9300 is recommended as it will reduce the effects of extraneous noise for rep orted detection. the SX9300 includes several conditions for debounce: close, far, and data detection. bits 7 6 average pos/neg debouncing 0 0 off 0 1 2 samples 1 0 4 samples 1 1 8 samples table 14: cps_avgdeb 6.2.6 set cps_avgnegfilt[5:3] & cps_avgposfilt[2:0] (average neg/pos filters) the SX9300 includes circuitry to average out the de tected signals. these detected signals can be both positive and negative, and so there are registers to control both the positive and negative averaging filter co efficients. there are eight (8) settings possible in each of th ese filters ranging from off up to highest filterin g. use of these filters is recommended for noisy environment and represents a tradeoff detection response versus false triggering. see cps_avgnegfilt and cps_avgposfilt for register and bit locations.
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 23 SX9300 ultra low power, dual channel smart proximity sar compliant solution 6.2.7 set cps_fs[4:3] (sampling frequency) the capacitance sampling frequency can be changed i n cps_ctrl2 if the environment is particularly nois y. changing this frequency affects the capacitance sen sing period. it is recommended to use the 167 khz sampling frequency. bits 4 3 sampling frequency 0 0 83 khz 0 1 125 khz 1 0 167 khz 1 1 reserved, do not use table 15: sampling frequency control 6.2.8 set cps_res[2:0] (resolution factor) the cps resolution factor has 8 possible settings t hat range from coarsest to very fine that controls the total number of measurements per sensor in a scan period. along with the cps sampling frequency, changing t his register affects the SX9300 sensing period. this r egister is located in cps_ctrl2. bits 2 1 0 resolution 0 0 0 coarsest 0 0 1 very coarse 0 1 0 coarse 0 1 1 medium coarse 1 0 0 medium 1 0 1 fine 1 1 0 very fine 1 1 1 finest table 16: cps resolution factor 6.2.9 set cps_avgtrs[7:0] (averaging threshold) the SX9300 performs averaging on all capacitive mea surements to determine when to perform a calibratio n cycle. the cps_avgtrs register is used to set an 8 -bit positive and negative threshold that determine s when a calibration is internally requested. typically the user would set this register to be between 1000000 0 [7:0] to 11000000 [7:0] which corresponds to ? to ? of the s ystem dynamic range.
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 24 SX9300 ultra low power, dual channel smart proximity sar compliant solution 6.3 additional parameter settings further application customization is possible to co ntrol scan period, enabled sensors and individual s ensor interrupts are also possible. scan period affects both power dissipation and detection reaction time. 6.3.1 set cps_period[6:4] (scan period) this register controls the scan period of the sx930 0 over a range of 30ms to 400ms. bits 6 5 4 scan period (ms) 0 0 0 30 0 0 1 60 0 1 0 90 0 1 1 120 1 0 0 150 1 0 1 200 1 1 0 300 1 1 1 400 table 17: scan period 6.3.2 set cps_en [3:0] (enable capacitive sensor in puts) if one set of sar capacitive sensors is not require d, they can be disabled in this register. each bit in this register corresponds to a specific sensor input. a logic 1 enables the capacitive sensor input, while a logi c 0 disables a capacitive input. inputs must be disabled in pai rs. cs0a & cs0b = bits [1:0] cs1a & cs1b = bits [3:2] 6.3.3 set irq_enable [6:3] (enable interrupt source s) there are a number of interrupt sources that the sx 9300 can report. a logic 1 in the specific locat ion will enable the specific interrupt as shown below. sarirqen [6]: enables the sar proximity detection irq sarrlsirqen [5]: enables the sar proximity no dete ct irq compdoneirqen [4]: enables the compensation done no tification irq convirqen [3]: enables the conversion completion do ne notification irq
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 25 SX9300 ultra low power, dual channel smart proximity sar compliant solution 7 i2c i nterface the i2c implemented on the SX9300 is compliant with : - standard (100kb/s) and fast mode (400kb/s) - i2c standard slave mode - 7 bit address (default is 0x28 assuming a1=a0=0). the host can use the i2c to read and write data at any time, and these changes are effective immediate ly. therefore the user should ideally disable the senso r before changing settings, or discard the results while changing (section 3.2). there are four types of i2c registers: - control and status (read). these registers give information about the status of the capacitive sens ors - operation control (read/write). these registers control operating modes. - cap sensor control and parameters (read/write) - cap sensor data read back (read) the i2c can be used to read and write from a start address and then perform read or writes sequentiall y, and the address increments automatically. supported i2c access formats are described in the n ext sections. 7.1 i2c write the format of the i2c write is given in figure 12. after the start condition [s], the slave address ( sa) is sent, followed by an eighth bit (0) indicating a write. the SX9300 then acknowledges [a] that it is being addressed, and the master sends an 8 bit data byte consisting of the SX9300 register address (ra). the slave acknowledges [a] and the master sends the appropria te 8 bit data byte (wd0). again the slave acknowle dges [a]. in case the master needs to write more data, a succeeding 8 bit data byte will follow (wd1), ack nowledged by the slave [a]. this sequence will be repeated u ntil the master terminates the transfer with the st op condition [p]. figure 12: i2c write the register address is incremented automatically w hen successive register data (wd1...wdn) is supplie d by the master.
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 26 SX9300 ultra low power, dual channel smart proximity sar compliant solution 7.2 i2c read the format of the i2c read is given in figure 13. after the start condition [s], the slave address (s a) is sent, followed by an eighth bit (0) indicating a write. the SX9300 then acknowledges [a] that it is being addressed, and the master responds with an 8-bit data consisti ng of the register address (ra). the slave acknowl edges [a] and the master sends the repeated start conditi on [sr]. once again, the slave address (sa) is sen t, followed by an eighth bit (1) indicating a read. the SX9300 responds with an acknowledge [a] and th e read data byte (rd0). if the master needs to read more data it will acknowledge [a] and the SX9300 will se nd the next read byte (rd1). this sequence can be repeate d until the master terminates with a nack [n] follo wed by a stop [p]. figure 13: i2c read
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 27 SX9300 ultra low power, dual channel smart proximity sar compliant solution 7.3 register overview add reg acc bits field reset function general control & status 0x00 irqstat r 7 resetirq 1 reset event occurred 6 tchirq 0 sensor proximity detected 5 rlsirq 0 sensor detection release condition interrupt r/w 4 compdone 0 compensation complete. writing a one in this bit trigs a compensation on all channels r 3 convirq 0 conversion cycle complete 2:1 not used 00 not used 0 txenstat 0 report txen pad status 0x01 tchcmpstat r 7 sarstat3 0 determines if proximity has been detected for the pair cs1a/cs1b 6 sarstat2 0 determines if a human body has been detected for the pair cs1a/cs1b 5 sarstat1 0 determines if a proximity has been detected for the pair cs0a/cs0b 4 sarstat0 0 determines if a human body has been detected for the pair cs0a/cs0b 3:0 compstat 1111 specifies which capacitive sensor(s) has a compensation pending general operations c ontrol 0x03 irq_enable r 7 not used 0 not used r/w 6 sarirqen 0 enables the detection irq 5 sarrlsirqen 0 enables the release irq 4 compdoneirqen 0 enables the compensation irq 3 convirqen 0 enables the conversion irq r 2:0 not used 000 not used cap sensing c ontrol 0x06 cps_ctrl0 r/w 7 not used 0 not used 6:4 cps_period 000 scan period : 000: 30 ms 001: 60 ms 010: 90 ms 011: 120 ms 100: 150 ms 101: 200 ms 110: 300 ms 111 : 400 ms 3:0 cps_en 1111 enables cs0a through cs1b 0x07 cps_ctrl1 r/w 7:6 cps_sh 01 cg bias/shield usage. 00 : off, cg high-z (off) 01: on(def.) 10: reserved 11: reserved 5:2 0000 not used r/w 1:0 cps_cinr 00 capacitance range: 00: large
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 28 SX9300 ultra low power, dual channel smart proximity sar compliant solution 01: medium large 10: medium small 11: small 0x08 cps_ctrl2 r/w 7 not used 0 not used 6:5 cps_digital_gain 00 set digital gain factor 00: gain = 1 01: gain = 2 10: gain = 4 11: gain = 8 4:3 cps_fs 01 sampling frequency 00: 83 khz 01: 125 khz 10: 167 khz (typical) 11: reserved 2:0 cps_res 000 resolution control 000: coarsest . 100: medium . 111: finest 0x09 cps_ctrl3 r/w 7 not used 0 not used 6 cps_dozeen 1 enables doze mode 5:4 cps_dozeperiod 00 when doze is enabled, the cap sensing period moves from cps_period to cps_period * : 00: 2* cps_period 01: 4* cps_period 10: 8*cps_period 11: 16*cps_period 3:2 reserved 00 must be 00 1:0 cps_rawfilt 00 raw filter coefficient 00: off 01: low 10: medium 11: high (max filtering) 0x0a cps_ctrl4 r/w 7:0 cps_avgtrs 00000000 average pos/neg threshold = 8 x reg 0x0b cps_ctrl5 r/w 7:6 cps_avgdeb 00 average pos/neg de- bouncer: 00: off 01: 2 samples 10: 4 samples 11: 8 samples 5:3 cps_avgnegfilt 000 average negative filter coefficient : 000: off 001: lowest . . 111: highest (max. filter) 2:0 cps_avgposfilt 000 average positive filter coefficient : 000: off 001: lowest . .. 111: highest (max. filter) 0x0c cps_ctrl6 r/w 7:5 not used 000 not used
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 29 SX9300 ultra low power, dual channel smart proximity sar compliant solution 4:0 cps_trs 00000 defines the touch/prox detection threshold for all sensors. see table 12 0x0d cps_ctrl7 r/w 7 cps_cmpautooff 0 disables the automatic compensation trigged by average 6 cps_cmptrg 0 0: compensate channels independently 1: compensate all channels when triggered 5:4 cps_hyst 00 detection hysteresis 00: 32 01: 64 10: 128 11: 256 3:2 cps_clsdeb 00 close debouncer 00: off 01: 2 samples 10: 4 samples 11: 8 samples 1:0 cps_fardeb 00 far debouncer 00: off 01: 2 samples 10: 4 samples 11: 8 samples 0x0e cps_ctrl8 r/w 7:4 cps_stuck 0000 stuck at timeout timer : 0000 : off 00xx: increment every cps_stuck x 64 active frames 01xx: increment every cps_stuck x 128 active frames 1xxx: increment every cps_stuck x 256 active frames 3:0 cps_cmpprd 0000 periodic compensation 0: off else : increment every cps_compprd x 128 active frames sensor r eadback 0x20 cpsrd r 7:2 not used 000000 not used r 1:0 cpsrd 00 determines which sensor data will be available in the next reg read. 0x21 usemsb r 7:0 sensusemsb 00000000 provides the useful information for monitoring purposes. signed, 2's complement format 0x22 uselsb r 7:0 sensuselsb 00000000 0x23 avgmsb r 7:0 sensavgmsb 00000000 provides the average information for monitoring purposes. signed, 2's complement format 0x24 avglsb r 7:0 sensavglsb 00000000 0x25 diffmsb r 7:0 sensdiffmsb 00000000 provides the diff information for monitoring purposes. signed, 2's complement format 0x26 difflsb r 7:0 sensdifflsb 00000000 0x27 offmsb r/w 7:0 sensoffmsb 00000000 offset compensation dac
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 30 SX9300 ultra low power, dual channel smart proximity sar compliant solution 0x28 offlsb r/w 7:0 sensofflsb 00000000 code. this is writable to allow forcing some dac codes. when written, the internal dac code is updated after the write of the lsb reg. msb and lsb regs should be written in sequence. 0x29 delta r 3:0 sensdelta 0000 sar value delta (difference) reading. signed, 2's complement format (see register 0x20) 0x2a ratio r 7:0 senseratio 00000000 ratio of the sar values. unsigned. (see register 0x20) 0x7f i2csoftreset w 7:0 softreset 00000000 write 0xde and reset the chip sar mode registers 0x0f deb_deltatrs r/w 7:6 not used 00 not used 5:4 cps_deb 00 data debouncing associated with detection/release (useful in a noisy environment): 00: off 01: 2 samples 10: 4 samples 11: 8 samples 3:0 cps_deltatrs 0000 defines the delta detection threshold thats applied to all sensors. see table 9 0x10 cps_ratiotrs r/w 7:0 cps_ratiotrs 00000000 defines the ratio detection threshold applied to all sensors table 18: register overview
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 31 SX9300 ultra low power, dual channel smart proximity sar compliant solution 7.4 sar sensor design this section describes how to properly design sar s ensors. the sar sensors for the SX9300 can be desi gned in a variety of shapes depending on the physical re quirements of the system. in the drawing below, the yellow areas represent co pper (conductor) and the gray area represents a non - conductor and is the distance r2 C r1 (spacing betw een the two copper areas). figure 14: typical sar capacitive sensor csxa and csxb copper areas refer to the SX9300 sensor inputs. important note: the a and b sensors cannot be swapped on the sx 9300. the outer copper area is always the a sensor, and the inner copper area is always the b sensor. also, the area of a csxb sensor and csxa sensor must be designed to be nearl y equal. the radius r1 sets the area of sar sensor csxb, w hile the radius r3 C r2 sets the area of sar sens or csxa. for circular capacitive sensors shown above where r1 is very nearly equal to r2, then the area of csxa is defined by r3 = 2 x r1 this approximation is also true for square type sen sors
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 32 SX9300 ultra low power, dual channel smart proximity sar compliant solution 8 p ackaging i nformation 8.1 package outline drawing figure 15: package outline drawing
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 33 SX9300 ultra low power, dual channel smart proximity sar compliant solution 8.2 land pattern figure 16: package land pattern
wireless & sensing products datasheet revision 1.8 june 27, 2012 ? 2012 semtech cor poration www.semtech.com 34 SX9300 ultra low power, dual channel smart proximity sar compliant solution contact information semtech 2012 all rights reserved. reproduction in whole or in p art is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or co ntract, is believed to be accurate and reliable and may be cha nged without notice. no liability will be accepted by the publisher for any consequence of its use. publicat ion thereof does not convey nor imply any license u nder patent or other industrial or intellectual property rights. semtech assumes no responsibility or liab ility whatsoever for any failure or unexpected operation resulting from misuse, neglect improper installatio n, repair or improper handling or unusual physical or electri cal stress including, but not limited to, exposure to parameters beyond the specified maximum ratings or operation outside the specified range. semtech products are not designed, intended, author ized or warranted to be suitable for use in life-support applications, devi ces or systems or other critical applications. inclusion of semtech products in suc h applications is understood to be undertaken solely at the customers own risk. s hould a customer purchase or use semtech products for any such unauthorized applicat ion, the customer shall indemnify and hold semtech and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs damages and attorney fees which could arise. notice: all referenced brands, product names, servi ce names and trademarks are the property of their respective owners. semtech corporation wireless and sensing products division 200 flynn road, camarillo, ca 93012 phone: (805) 498-2111 fax: (805) 498-3804

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