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1 datasheet low power ambient light and proximity sensor with enhanced infrared rejection ISL29038 the ISL29038 is a low power am bient light sensor (als) and proximity (prox) sensor. it has a built-in ir-led driver for proximity function. the als func tion measures the amount of light (in the visible spectrum) incident on the ISL29038. the als function has a programmable ambient ir-rejection, which allows fine tuning of light source variations and is ideal for light sensor applications under dark protective glass. the als provides a 12-bit measurement. a passive optical filter removes unwanted wavelengths (ir or ultraviolet) to ensure accurate als measurement. the proximity function includes a new offset adjustment to compensate for the ir light re flected off the inside of the protective glass cover and back to the ISL29038 sensor. this offset adjustment allows the sensor to compensate for these internal reflections and preserve the dynamic range of the proximity measurement. the built-in current-driver pulses an external infrared led at a programmed current for 90s. the infrared light that is reflected and received by ISL29038 is digitized by an 8-bit adc. the proximity sensor also has a passive optical filter designed to pass ir and reject visible wavelengths. the ISL29038 provides a hardware pin to indicate an interrupt event. the interrupt pin saves po wer as the host microcontroller can ?wake-up? on an interrupt event and does not need to poll the device for an interrupt event. the interrupt generator is user configurable and provides several options for als and prox trigger configurations. the ISL29038 supports an smbus compatible i 2 c interface for configuration and control. features ? ideal for applications un der dark or tinted glass ? enhanced ambient sunlight rejection to 40k lux ? programmable proximity sleep time between proximity measurements optimizes power consumption ? hardware interrupt - no polling required ? programmable ir compensation to fine tune als performance for various glass compositions ? up to 4000 lux, four selectable als ranges ? programmable ir led drive current to 250ma ? operates from 2.25v to 3.63v v dd ? power-down i dd, typical 0.2a dc ? tiny 2.1x2.0x0.7 (mm) odfn package applications ? display dimming and adjustment - mobile devices: smart phones, pda, gps - computing: monitors, laptops, notebooks -picture frames, tablet_pcs, lcd_tv ? object detection - touchscreen disabling -smart power-saving figure 1. typical applications circuit figure 2. proximity sensitivity vdd_irled vdd_analog r 2 100 c 1 1f c 2 1f r 1 499k 1 2 3 4 8 7 6 5 gndir avdd agnd rext irdr int sda scl d 1 irled u1 ISL29038 vdd_pullup scl, sda and int sda scl int pull ups smbus master r 1 : 499k 1% resistor r 2 : 100 5% resistor c 1 , c 2 : 1f ceramic 10v capacitor d 1 : osram sfh4650 infrared led 0 10 20 30 40 50 60 70 80 90 100 020 full-scale range (%) 80 60 40 18% grey card proxim ity distance (mm) 31.25ma 62.5ma 125ma 250ma january 23, 2015 fn7851.1 caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | copyright intersil americas llc 2012, 2014. all rights reserved intersil (and design) is a trademark owned by intersil corporation or one of its subsidiaries. all other trademarks mentioned are the property of their respective owners.
ISL29038 2 fn7851.1 january 23, 2015 submit document feedback pin configuration ISL29038 (8 ld odfn) top view figure 3. ISL29038 block diagram vdd rext gnd scl ir photodiode photodiode 4 3 5 2 fosc iref irdr array als photodiode amplifiers (als and ir) array dual channel adcs 8 int 7 command register data register i 2 c ir driver interrupt sda 6 gndir 1 1 2 3 8 7 6 gndir vdd gnd irdr int sda 4 5 rext scl thermal pad pin description pin# name description 1 gndir ground for irdr led current. 2 vdd positive supply: 2.25v to 3.63v. 3gndground. 4 rext external resistor, connect to gnd pin through a 499k ? 1% resistor. 5scli 2 c serial clock input. 6sdai 2 c serial data input/output. 7int active low, open-drain output. 8 irdr ir-led driver sink - connect to ir led cathode. - tpad thermal pad - connect to gnd. ordering information part number ( notes 1 , 2 , 3 ) part marking v dd range (v) temp range (c) package pkg. dwg. # ISL29038iroz-t7 n/a 2.25 to 3.63 -40 to +85 8 lead odfn l8.2.1x2.0 ISL29038iroz-evalz evaluation board notes: 1. refer to tb347 for details on reel specifications. 2. these intersil pb-free plastic packaged products employ special pb-free material sets; molding compounds/die attach materials and nipdau plate-e4 termination finish, which is rohs compliant and compatible with both snpb and pb-free soldering operations. intersil pb-free pr oducts are msl classified at pb-free peak reflow temp eratures that meet or exceed the pb-fr ee requirements of ipc/jedec j std-020. 3. for moisture sensitivity level (msl), see device information page for ISL29038 . for more information on msl see techbrief tb477 .
ISL29038 3 fn7851.1 january 23, 2015 submit document feedback absolute maximum ratings thermal information v dd supply voltage between vdd and gnd . . . . . . . . . . . . . . . . . . . . . .4.0v i 2 c bus pin voltage (scl, sda). . . . . . . . . . . . . . . . . . . . . . . . . -0.5v to 4.0v i 2 c bus pin current (scl, sda). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <10ma rext pin voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.5v to vdd + 0.5v irdr pin voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.5v int pin voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5v to 4.0v int pin current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <10ma esd rating human body model ( note 6 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kv thermal resistance (typical) ? ja (c/w) ? jc (c/w) 8 ld odfn ( notes 4 , 5 ) . . . . . . . . . . . . . . . . 88 14 maximum die temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +90c storage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40c to +100c operating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40c to +85c pb-free reflow profile (*) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see tb477 *peak temperature during solder reflow +260c max caution: do not operate at or near the maximum ratings listed for extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. notes: 4. ? ja is measured in free air with the component mounted on a high effective thermal conductivity test board with ?direct attach? fea tures. see tech brief tb379 . 5. for ? jc , the ?case temp? location is the center of the exposed metal pad on the package underside. 6. tested per jesd22-a114e, esd on all pins is 2kv except ir dr, which is 1.5kv. electrical specifications v dd = 3.0v, t a = +25c, r ext = 499k 1% tolerance. parameter description test condition min ( note 7 )typ max ( note 7 )units input power v dd power supply range 2.25 3.0 3.63 v i dd_off supply current when powered down als_en = 0; prox_en = 0 0.2 1.0 a i dd_norm supply current for als+prox in sleep time als_en = 1; prox_en = 1 125 140 a i dd_prx_slp supply current for prox in sleep time als_en = 0; prox_en = 1 95 a i dd_als supply current for als als_en = 1; prox_en = 0 95 a adc (als and prox) t intgr_als 12-bit als conversion time 80 95 110 ms t intgr_prox 8-bit prox conversion time 0.4 0.50 0.6 ms data als_0 als result when dark e ambient = 0 lux, 2k range 1 counts data als_f full-scale als adc code e ambient > selected range maximum lux 4095 counts data 1 data output variation over light sources: fluorescent, incandescent and sunlight ambient light sensing, no cover glass after programmable active ir compensation ( note 8 ) 10 % data 2 data output variation over light sources: fluorescent, incandescent and sunlight ambient light sensing under cover glass after programmable active ir compensation ( note 8 ) 10 % linearity als adc data linearity 20% - 80% of full range 5 % data als_0 light count, als_range 125 lux e = 50 lux ( note 9 ), als_range = 0 1555 1767 1979 counts data als_1 light count, als_range 250 lux e = 50 lux ( note 9 ), als_range = 1 771 876 981 counts data als_2 light count, als_range 2000 lux e = 300 lux ( note 9 ), als_range = 2 585 665 745 counts data als_3 light count, als_range 4000 lux e = 300 lux ( note 9 ), als_range = 3 292 331 371 counts data prox_0 prox data without object in path 1counts data prox_f full-scale prox adc code 255 counts
ISL29038 4 fn7851.1 january 23, 2015 submit document feedback proxwash washout bit activation level norwood solar emulator 40k lux proxoffsetmax maximum prox offset, referenced to proximity adc range 512 lsb proxoffsetinc proximity offset adjust increment referenced to proximity adc range 27 lsb led driver (irdr pin) t r rise time for irdr sink current r load = 15 at irdr pin, 20% to 80% 25 ns t f fall time for irdr sink current r load = 15 at irdr pin, 80% to 20% 15 ns i irdr_0 irdr sink current prox_dr = 0; v irdr = 0.5v 31.25 ma i irdr_1 irdr sink current prox_dr = 1; v irdr = 0.5v 62.5 ma i irdr_2 irdr sink current prox_dr = 2; v irdr = 0.5v 125 ma i irdr_3 irdr sink current prox_dr = 3; v irdr = 0.5v 250 ma i irdr_leak irdr leakage current prox_en = 0; v irdr = 3.63v 0.001 1 a v irdr irdr pin voltage compliance regi ster bit prox_dr = 0 0.50 4.3 v t pulse i irdr on time per prox reading 90 s miscellaneous v ref voltage of rext pin als_en = 1 or prox_en = 1 0.52 v electrical specifications v dd = 3.0v, t a = +25c, r ext = 499k 1% tolerance. (continued) parameter description test condition min ( note 7 )typ max ( note 7 )units i 2 c electrical specifications for scl and sda unless otherwise noted, v dd = 3v, t a = +25c, r ext = 499k 1% tolerance ( note 11 ). symbol parameter test conditions min ( note 7 ) typ max ( note 7 ) units v i 2 c supply voltage range for i 2 c interface 1.7 3.63 v f scl scl clock frequency 400 khz v il scl and sda input low voltage 0.55 v v ih scl and sda input high voltage 1.25 v v hys hysteresis of schmitt trigger input 0.05v dd v v ol low-level output voltage (open-drain) at 4ma sink current 0.4 v i i input leakage for each sda, scl pin -10 10 a t sp pulse width of spikes that must be suppressed by the input filter 50 ns t aa scl falling edge to sda output data valid 900 ns c i capacitance for each sda and scl pin 10 pf t hd:sta hold time start condition after this period, the first clock pulse is generated 600 ns t low low period of the scl clock measured at the 30% of vdd crossing 1300 ns t high high period of the scl clock 600 ns t su:sta set-up time for a start condition 600 ns t hd:dat data hold time 30 ns t su:dat data set-up time 100 ns
ISL29038 5 fn7851.1 january 23, 2015 submit document feedback t r rise time of both sda and scl signals ( note 12 ) 20 + 0.1xc b ns t f fall time of both sda and scl signals ( note 12 ) 20 + 0.1xc b ns t su:sto set-up time for stop condition 600 ns t buf bus free time between a stop and start condition 1300 ns c b capacitive load for each bus line 400 pf r pull-up sda and scl system bus pull-up resistor maximum determined by t r and t f 1k t vd;dat data valid time 0.9 s t vd:ack data valid acknowledge time 0.9 s v nl noise margin at the low level 0.1vdd v v nh noise margin at the high level 0.2vdd v notes: 7. parameters with min and/or max limits are 100% tested at +25c , unless otherwise specified. te mperature limits established by characterization and are not production tested. 8. cover glass assumes fixed infrared/visib le light transmissivity ratio of 10. 9. the led light source irradiance is calibrated to produce the sa me als count as a fluorescent light source of the same lux lev el. 10. an 850nm infrared led is used in production test for proximity/ir sensitivity testing. 11. all parameters in i 2 c electrical specifications table are guaranteed by design and simulation. 12. c b is the capacitance of the bus in pf. i 2 c electrical specifications for scl and sda unless otherwise noted, v dd = 3v, t a = +25c, r ext = 499k 1% tolerance ( note 11 ). (continued) symbol parameter test conditions min ( note 7 ) typ max ( note 7 ) units figure 4. i 2 c timing diagram
ISL29038 6 fn7851.1 january 23, 2015 submit document feedback ISL29038 configuration and control i 2 c interface ISL29038 configuration and control is performed using the i2c or smbus. the ISL29038?s i2c interface slave address is internally hard wired as 8?b1000100x, where x denotes the r/w bit. every i2c transaction begins with the master asserting a start condition (sda falling while scl remains high). the first transmitted byte is initiated by the master and includes 7 address bits and a r/w bit. the slave is responsible for pulling sda low during the ack time after every transmitted byte. figure 5 shows a sample one-byte read. the i2c bus master always drives the scl (clock) line, while either the master or the slave can drive the sda (data) line. each i 2 c transaction ends with the master asserting a stop condition (sda rising while scl remains high). for more information about the i 2 c standard, consult the philips ? i 2 c specification documents. timing specifications are included in ? i 2 c electrical specifications ? on page 4 . the timing parameters are defined in figure 4 . the i 2 c interface on the ISL29038 supports single and multiple byte read and write transfers using the random-read/write protocol. the ISL29038 does not support i 2 c ?repeat start? protocol. note: that in most system implementations, the ISL29038 is connected to a single i 2 c master with one or more slave devices, consequently, absence of ?repeat start? function does not adversely affect i 2 c bus system performance. figure 5. i 2 c driver timing diagram for master and slave connected to common bus start w a a a6 a5 a4 a3 a2 a1 a0 w a r7 r6 r5 r4 r3 r2 r1 r0 a a6 a5 a4 a3 a2 a1 a0 w a a a a d7 d6d5d4 d3d2 d1d0 1357 1357 123456 9246 stop start sda driven by master device address sda driven by ISL29038 data byte0 register address slave device address i 2 c data sda driven by master sda driven by master 2468 924689 78135789 i 2 c sda i 2 c sda i 2 c clk master (ISL29038)
ISL29038 7 fn7851.1 january 23, 2015 submit document feedback typical performance curves figure 6. proximity sensitivity ( note 13 ) figure 7. als sensitivity ( note 14 ) figure 8. proximity ambient light rejection ( note 15 ) figure 9. als angular sensitivity ( note 16 ) notes: 13. the ISL29038 proximity distance sweeps with different irdr led current settings using an 18% grey card reflector. 14. the ISL29038 ambient light sensor spectral response when comp ared to a theoretical cie 1924 photopic curve. the ?blue? line shows the ISL29038 response and the ?red? line depicts the cie 1924 photopic curve. 15. the ISL29038 proximity ambient light reject ion using a norwood solar em ulator. at 40k lux ambient light level, the proximity washout count (reg 0x0d[7:1]) is 127 indicating a saturation in proximity signal pr ocessing path. the proximity washout bit 0x0d[0] is active at a pproximately 90% of the maximum level. at 10% initial prox count (due to optical le akage from ir led to the ISL29038), the prox data error is under 2%. at 50% initial prox count (severe optical leakage), the prox data error is about 7%. 16. the ambient light sensor angu lar sensitivity of the ISL29038 using a white led light source. 0 10 20 30 40 50 60 70 80 90 100 020 full-scale range (%) 80 60 40 18% grey card proximity distance (mm) 125ma 250ma 31.25ma 62.5ma 0 10 20 30 40 50 60 70 80 90 100 300 400 500 600 700 800 900 1000 1100 full-scale range (%) wavelength (nm) range: 2k lux als response (blue) cie 1924 photopic curve ambient light level (lux) 0 8k 16k 24k 32k 40k 15 10 value change (% fsr) 5 50% 10% 0 0 10 20 30 40 50 60 70 80 90 100 -90 -60 -30 0 30 60 90 angle () normalized sensitivity (%)
ISL29038 8 fn7851.1 january 23, 2015 submit document feedback ISL29038 register set table 1. configuration and control registers address (hex) register name power-on default register access bit fields function name/value function 0x00 device id b11000xxx ro [7:0] device identification [7:3] [11000] ISL29038 device id [2:0] reserved 0x01 config0 0x00 rw [7:0] proximity configuration [7:6] reserved rw [5] prox_en proximity enable/disable [1] enable [0] disable rw [4:2] prox_slp proximity sleep time select [000] 400ms [001] 100ms [010] 50ms [011] 25ms [100] 12.5ms [101] 6.25ms [110] 3.125ms [111] 0ms rw [1:0] irdr_drv ir led current [00] 31.25ma [01] 62.5ma [10] 125ma [11] 250ma 0x02 config1 0x00 rw [7:0] proximity/als configuration rw [7] int_alg interrupt algorithm [1] window comparator [0] hysteresis window rw [6:3] prox_offset proximity offset compensation rw [2] als_en ambient light sensing enable/disable [1] enable [0] disable rw [1:0] als_range ambient light sensor range select [00] 125 lux [01] 250 lux [10] 2000 lux [11] 4000 lux 0x03 config2 0x00 rw [7:0] als_ir_comp amb ient light sensor ir compensation rw [7:5] reserved rw [4:0] alsircomp als infra red compensation (unsigned binary) 0x04 intconfig 0x10 rw [7:0] intconfig interrupt configuration, status and control
ISL29038 9 fn7851.1 january 23, 2015 submit document feedback ro [7] prox_int_flg proximity interrupt flag [1] proximity interrupt event [0] no proximity interrupt event rw [6:5] prox_prst proximity interrupt reporting persistency [00] int after 1 proximity flag event [01] int after 2 consecutive proximity flag event [10] int after 4 consecutive proximity flag event [11] int after 8 consecutive proximity flag event ro [4] pwr_fail power failure (brown-out) alarm [1] brown-out detected [0] normal operation ro [3] als_int_flg ambient light sensor interrupt flag [1] als interrupt flag event [0] no als interrupt flag event rw [2:1] als_int_prst als interrupt reporting persistency [00] int after 1 als flag event [01] int after 2 consecutive als flag event [10] int after 4 consecutive als flag event [11] int after 8 consecutive als flag event rw [0] int_cfg interrupt output (pin) configuration [1] interrupt if als and prox event [0] interrupt if als or prox event 0x05 prox_int_tl 0x00 rw [7:0] prox_int_tl proximity interrupt low threshold 0x06 prox_int_th 0xff rw [7:0] prox_int_th p roximity interrupt high threshold 0x07 als_int_tl 0x00 rw [7:0] als_int_tl1 als interrupt low threshold bit[11:4] 0x08 als_int_tlh 0x0f rw [7:0] als interrupt low/high threshold bits [7:4] als_int_tl0 als interru pt low threshold bit[3:0] [3:0] als_int_th1 als interrupt high threshold bit[11:8] 0x09 als_int_th 0xff rw [7:0] als_int_th0 al s interrupt high threshold bit[7:0] 0x0a prox_data ro [7:0] prox_data proximity data (unsigned binary) 0x0b als_data_hb ro [7:0] als_data_hb als data high byte [7:4] set to 0000 [3:0] als data bit[11:8] 0x0c als_data_lb ro [7:0] als_data_lb als data bit[7:0] 0x0d prox_ambir ro [7:0] prox_ambir proximity mode ambient ir measurement [7:1] proximity mode ambient ir component ro [0] prox_wash proximity washout status [1] proximity washout detected [0] normal proximity operation 0x0e config3 0x00 [7:0] softreset software reset 0x38 initiate soft reset 0x00 normal operation table 1. configuration and control registers (continued) address (hex) register name power-on default register access bit fields function name/value function
ISL29038 10 fn7851.1 january 23, 2015 submit document feedback registers 0x01, 0x02 are used to configure the primary proximity and als parameters. register 0x03 is used for optimizing ir compensation in als measurements. a procedure to optimize ir compensation is described in ? als ir compensation ? on page 11 . register 0x04 is the interrupt configuration and status register, and is used primarily to indicate interrupt events from proximity and als measurements. a pwr_fail bit to indicate a ?brown-out? event is available and is set in case of a power supply interruption. a ?brown-out? event does not generate a hardware interrupt. the host micro-controller must clear this bit by writing a ?0? to reg 0x04[4]. register 0x04 is also used to configure als and proximity interrupt persistency and the operation of the int pin. registers 0x05 and 0x06 are used to set the proximity ?low? and ?high? threshold for proximity interrupt event generation. registers 0x07, 0x08 and 0x09 are used to set the als ?low? and ?high? threshold. two 12-bit numbers span three address locations as shown in table 1 . data registers 0x0a holds result of proximity conversion. the proximity result should be validated by ?washout? bit in reg 0x0d[0]. registers 0x0b and 0x0c hold results of an als measurement. the als data is 12 bits wide. le ast significant byte of the als data is available at address 0x0c and most significant byte (msb) of als data is available at address 0x0b. the msb is right justified, i.e., the upper nibble is always zero and lower nibble contains four data bits. register 0x0d[7:1] contains ambient ir measurement in proximity measurement phase. this measurement is for detecting ambient washout condition, which is indicated by reg 0x0d[0] being ?high?. proximity ?washout? is described in ? proximity ambient washout detection ? on page 11 . a software reset can be initiated by writing 0x38 to reg 0x0e. ISL29038 operation photodiodes and adcs the ISL29038 contains two photodiode arrays, which convert photons (light) into current. the als photodiodes are designed to mimic the human eye?s wavelength response curve to visible light. the als photodiodes? current output is digitized by a 12-bit adc. the als adc output is accessed by reading from reg 0x0b and 0x0c when the adc conversion is completed. the als adc converter uses a ch arge-balancing architecture. charge-balancing is best suited fo r converting small current signals in the presence of periodic ac noise. the ISL29038 targets an integration time of 90ms, which can vary 15% from nominal. the als integration time is intended to minimize 60hz flicker. the proximity sensor uses an 8-bit adc, which operates in a similar fashion. the irdr pin drives (pulses) an infrared led, the emitted ir reflects off an object back into the ISL29038, and the photo diodes convert the reflected ir to a current signal in 0.5ms. the adc subtracts the ir reading before and after the led is driven to remove ambient ir contribution. the als runs continuously with new data available every 90ms. the proximity sensor runs continuously with a time between conversions controlled by prox_slp (reg 0x01[6:4]). ambient light sensing the ISL29038 is set for ambient li ght sensing when register bit als_en = 1. four measurement ra nges from 125 lux to 4000 lux are available. the als measurement range is configured via reg 0x02[1:0]. proximity sensing when proximity sensing is enabled (prox_en = 1), the external ir led is driven for 100s by the built-in ir led driver through the irdr pin. the ir led current depends on pr ox_drv (reg 0x01[1:0]). drive current settings are as shown in table 1 . ir led drive is in high impedance state when not active. when the ir from the led reache s an object and gets reflected back to the ISL29038, the reflecte d ir light is converted into a current. this current is converted to digital data using an 8-bit adc. the proximity measurement takes 0.5ms for one conversion including the 90 s led drive time. the period between proximity measurements is determined by prox_slp (sleep time) in reg 0x01[4:2]. average led driving current consumption is given by equation 1 . a typical irdr scheme is 250ma pulses every 400ms, averaging about 56 a dc. total current consumption total current consumpt ion is the sum of i dd and i irdr . the irdr pin sinks current and the average ir dr current is calculated using equation 1 . the i dd depends on voltage and the mode of operation. for simplicity, equation 1 ignores proximity adc conversion time since it is mu ch smaller than the sleep time. als active 90ms 90ms 90ms prox sensor active irdr (current driver) als conversion time = 90ms (fixed) 0.50ms for prox conversion series of current pulses totaling 0.09ms sleep time (prox_slp) 90ms 90ms several s between conversions time time time ? figure 10. timing diagram for prox/als events - not to scale i lrdr ave ; i lrdr peak ; 90 ? s ? t sleep ---------------------------------------------------- - = (eq. 1)
ISL29038 11 fn7851.1 january 23, 2015 submit document feedback als ir compensation the ISL29038 is designed for oper ation under dark glass cover. glass or plastic covers can sign ificantly attenuate visible light and pass the infrared light without much attenuation. consequently, the ISL29038 under a glass cover experiences an ir rich environment. the on-chip als passive optical filt er on the ISL29038 is designed to block most of the ir incident on the als photo diodes. in addition, the ISL29038 provides a programmable active ir compensation that subtracts residu al ir still reaching the sensor. the als_ir_comp register (reg 0x 03[4:0]) allows fine tuning of the residual infrared component from the als output. the recommended procedure for determining als ir compensation is as follows: ? illuminate the ISL29038 based product with a light source without ir, such as a white led. record the als measurement and the lux level. ? illuminate the device with an ir led and the white led. take an als measurement and lux level measurement. ? adjust the als_ir_comp register (reg 0x03, bits 4:0) to compensate for the ir contribution. ? repeat steps above until the ir light source contribution to the als measurement is under 10 pe rcent assuming no change in lux level due to ir light source. proximity offset systems built with a protective glass cover over the ISL29038 can provide light ?leakage? or ?c rosstalk? from the ir led by reflection from the glass satu rating the proximity sensor measurement system ( figure 11 ). saturation can occur when the refl ection from the glass with no object in the proximity detection space exceeds the full scale of the measurement system. the ISL29038 proximity system provides a user programmable proximity offset correction to compensate for this reflection. the prox_ir_comp register (reg 0x02[6:3]) applies a corrective offset to the received signal prior to adc conversion, which allows the signal to be brought within the usable range of the proximity measurement system. proximity ambient washout detection optical proximity sensor can saturate when illuminated with excessive ambient light. the isl 29038 provides a warning flag when the proximity measurement may be erroneous due to excessive ambient light. the pr ox_wash register (reg 0x0d[0]) reports this condition. interrupts events the ISL29038 interrupts are de signed to minimize host microcontroller overhead of co ntinuous polling. the ISL29038 can generate interrupts on the results of an als measurement or proximity measurement. the als interrupt event als_flag (reg 0x04[3]) is governed by reg 0x07 through 0x09. two-12 bit high and low threshold values are written to these regi sters. the ISL29038 will set the als interrupt flag if the adc conversion count in registers 0x0b and 0x0c are outside the programmed thresholds. the als_flag is cleared by writing a ?0? to reg 0x04[3]. a proximity interrupt event (prox_flag) is governed by the high and low thresholds in reg 0x05 and 0x06 (prox_lt and prox_ht) and is indicated by reg 0x04[7]. prox_flag is set when the measured proximity data is more than the higher threshold. the proximity interrupt flag is cleared when the proximity data is lower than th e low proximity threshold or by writing a ?0? to reg 0x04[7]. the proximity interrupt generation can be selected between ?out-of-window? threshold and hysteresis schemes. when the prox_int_alg register (reg 0x02, bit 7) is set to 0, proximity uses a window comparator scheme; when set to 1, proximity uses a hysteresis scheme. in hysteresis mode, the interrupt event is generated if the proximity adc count is higher than the prox_ht threshold and the interrupt event is cleared when the proximity adc count is less than the prox_lt threshold. the interrupt event flag can also be cleared by writing a ?0? to reg 0x04[7]. interrupt persistence to minimize interrupt events du e to ?transient? conditions, an interrupt persistency option is av ailable for both als and proximity measurements. persistency requires ?x-consecutive? interrupt flags before the int pin is driven low. both als and prox have their own independent interrupt persiste ncy options. als_prst and prox_prst configuration are controlled from reg 0x04. power-up and ?brown-out? reset the ISL29038 has an enhanced power-on-reset system. a ?brown-out? detector flag in reg 0x04[4] informs the system that the device has powered-up properly. this flag should be reset as part of the initialization sequence. a ?brown-out? condition is defi ned as an operating condition when the power supply voltage is not within the specified limits. during the brown-out period at power-up, the i 2 c interface and the ir led driver are inactive. following brown-out, the i 2 c interface is re-initialized and the configuration registers are set to power-up default values. after power-up and during device initialization, host should ex amine that the pwr_fail flag figure 11. proximity set-up highlighting crosstalk reflected from cover glass led sensor pcb glass cover
ISL29038 12 fn7851.1 january 23, 2015 submit document feedback (reg 0x04[4]) is set and then clear the flag by writing ?0? to reg 0x04[4]. following power-up, a ?brown-out? condition, if detected, is reported by pwr_fail flag by re g 0x04[4]. device configuration registers are not set to their po wer-up default after ?brown-out?. pwr_fail flag should be periodically monitored to detect post power-up power supply interruption. power-down setting als_en (reg 0x02[2]) and prox_en (reg 0x01[5]) to ?0? puts the ISL29038 into a power-down state with power supply current dropping to less than 1a. all configuration registers are maintained in power-down mode. soft reset a software reset to ISL29038 can be initiated by writing 0x38 to reg 0x0e. following reset, all configuration registers are set to their default power-up state. after soft reset, the ISL29038 defaults to the power-down configuration. als data count read out a 2 byte i 2 c read from als_data_hb outputs msb 1 st data on sda. this data is lsb justified with a zero fill for unused bits. note: that the msb byte address prec edes the lsb byte address. the als count is 256*(als_data_hb) + als_data_lb. proximity detection of various objects proximity sensing relies on the amount of ir reflected back from objects. a perfect black object would absorb all incident light and reflect no photons. the ISL29038 is sensitive enough to detect black esd foam, which reflects only 1% of ir. blonde hair typically reflects more than brown hair and skin tissue is more reflective than human hair. ir penetrates into the skin and is reflected from within. as a result, the proximity count ge nerally peaks at contact and monotonically decreases as skin moves away. the reflective characteristics of skin are very di fferent from that of a inanimate object such as paper. typical application circuit a typical application circuit for the ISL29038 is shown in figure 12 . the ISL29038?s i 2 c address is internally hard wired as ?1000100x?, with x representing the r/w bit. the device can be connected to a system?s i 2 c bus together with other i 2 c compliant devices. it is important to ensure that there is no address conflict with other i 2 c devices on the bus. the scl, sda and int pins on ISL29038 are open drain and require pull-up resistors for proper system operation. values of the pull-up resistors is system dependent and can range from 2.2k to 10k depending upon the number of i 2 c devices on the bus. the proximity sensing system can be powered using a dual power supply or using a single po wer supply. in dual supply configuration, the ir led and the ISL29038 are powered from separate power supplies. the v dd irled can range from 2.25v to 5.0v and the v dd _analog can range from 2.25v to 3.63v. in dual supply configuration, resistor r 2 should not be installed. in single supply configuration, the ir led and the ISL29038 are powered from the same power source. the v dd _irled can range from 2.25v to 3.63v and the v dd _analog is derived from v dd _irled using resistor r 2 . in either power supply configurat ion, a 1f decoupling capacitor should be installed close to the avdd pin, and another 1f decoupling capacitor should be placed close to the ir led anode. figure 12. typical applications circuit vdd_irled vdd_analog r 2 100 c 1 1f c 2 1f r 1 499k 1 2 3 4 8 7 6 5 gndir avdd agnd rext irdr int sda scl d 1 irled u1 ISL29038 vdd_pullup scl, sda and int sda scl int pull ups smbus master r 1 : 499k 1% resistor r 2 : 100 5% resistor c 1 , c 2 : 1f ceramic 10v capacitor d 1 : osram sfh4650 infrared led
ISL29038 13 fn7851.1 january 23, 2015 submit document feedback soldering considerations convection heating is recomm ended for reflow soldering; direct-infrared heating is not recommended. the plastic odfn package does not require a custom reflow soldering profile. a standard reflow soldering profile with a +260c maximum is recommended. additional information regarding soldering ISL29038 is included in intersil technical brief tb477 . suggested pcb footprint refer to tb477 ,?surface mount assembly guidelines for optical dual flatpack no lead (odfn) package? before starting odfn product board mounting. additional information regarding soldering is also included in intersil technical brief tb477 . pcb layout considerations the ISL29038 is relatively insens itive to pcb layout. adherence to the following guidelines will ensure first pass success and best performance. route the i 2 c/smbus scl, sda and the int traces away from sources of switching noise. a 499k 1% tolerance resistor must be connected from the rext pin to agnd. this node also needs to be isolated from any switching noise. ISL29038 pins irgnd and agnd should connect to a low impedance ground with low re sistance and low inductance traces. ferrite beads and inductors should be avoided in the ground path. if necessary, due to rf consideration, the effects of dcr (dc resistance) should be evaluated on als and proximity system performance. a 1f ceramic decoupling capacitor should be placed as close to the avdd pin as possible. the ISL29038 drives the ir led with 0.09ms current pulses. to supply this pulsed current, a 1 to 10f bulk decoupling capacitor (c 1 ) must be connected from the ir led anode to the gndir pin to minimize instantaneous resist ive voltage drop. the connection from ir led cathode to the irdr pin should be short and with minimal inductance. similarly, connection from the ir led to vdd must be made with a low impedance trace. for most applications, a single power supply may be used to power the ir led and the ISL29038. use of resistor r 2 and capacitor c 2 ( figure 13 ) to help filter out the power supply noise generated from ir led switch ing is recommended for best ISL29038 performance when using a single power supply. for dual supply operation, resistor r 2 should not be installed. figure 13. 8 ld odfn sensor location outline - dimensions in mm 2.00 2.10 1 2 3 4 8 7 6 5 0.57 als sensor offset 0.03mm als sensor area 0.66mm x 0.24mm prox sensor offset 0.42mm prox sensor area 0.57mm x 0.16mm
ISL29038 14 intersil products are manufactured, assembled and tested utilizing iso9001 quality systems as noted in the quality certifications found at www.intersil.com/en/suppor t/qualandreliability.html intersil products are sold by description only. intersil corporat ion reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnished by intersil is believed to be accurate and reliable. however, no responsi bility is assumed by intersil or its subsid iaries for its use; nor for any infringem ents of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of i ntersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com fn7851.1 january 23, 2015 for additional products, see www.intersil.com/en/products.html submit document feedback about intersil intersil corporation is a leading provider of innovative power ma nagement and precision analog so lutions. the company's product s address some of the largest markets within the industrial and infrastr ucture, mobile computing and high-end consumer markets. for the most updated datasheet, application notes, related documentatio n and related parts, please see the respective product information page found at www.intersil.com . you may report errors or suggestions for improving this datasheet by visiting www.intersil.com/ask . reliability reports are also av ailable from our website at www.intersil.com/support revision history the revision history provided is for informational purposes only and is believed to be accurate, but not warranted. please go t o web to make sure you have the latest revision. date revision change january 23, 2015 fn7851.1 thermal information table on page 3: changed theta jc value from 10 to 14. configuration and control registers on page 8; under reg2 configure1 section: changed window comparator from 0 to 1 and hysteresis window from 1 to 0. october 12, 2012 fn7851.0 initial release.
ISL29038 15 fn7851.1 january 23, 2015 submit document feedback package outline drawing l8.2.1x2.0 8 lead optical dual flat no-lead plastic package (odfn) rev 3, 1/11 8x 0 . 35 0 . 05 b 0.10 a c 0.200.05 0.75 0.50 1.50 1.50 m 0.25 0.15 located within the zone indicated. the pin #1 indentifier may b e unless otherwise specified, tolerance : decimal 0.05 tiebar shown (if present) is a non-functional feature. the configuration of the pin #1 identifier is optional, but mus t be between 0.25mm and 0.35mm from the terminal tip. dimension applies to the metallized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to asme y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes: detail "x" side view typical recommended land pattern top view (2x) 0.10 index area pin 1 a b c seating plane base plane 0.08 0.10 see detail "x" c c 6 0 . 00 min. 0 . 05 max. 0 . 2 ref c 5 0.700.05 2.10 2.00 (6x0.50) (8x0.20) (8x0.55) (0.75) (1.50) 2.10 2.50 (8x0.20) bottom view index area pin 1 6 4

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