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charge - pump , parallel backlight driver with image content pwm input data sheet ADP8870 rev. b document feedback information furnished by analog devices is believed to be accurate and reliable. howe ver, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their res pective owners. one technology way, p.o. box 9106, norwood, ma 02062 - 9106, u.s.a. tel: 781.329.4700 ? 2012C 2014 analog devices, inc. all rights reserved. technical support www.analog.com features charge pump with automatic gain selection of 1 , 1.5 , and 2 for maximum efficiency two high accuracy ( 5%) phototransistor input s for automated ambient light sensing (als) 5 programmable ambient light - sensing zones for optimal backlight power sa vings independent als control of d7, for automated response of keypad l ighting to ambient light levels pwm input can be used for content adaptive brightness control (cabc) of any, or all, of the leds pwm input scales the led output current 7 independent , p rogrammable led drivers 6 drivers capable of 30 ma (max imum ) 1 driver capable of 60 ma ( maximum ) programmable maximum current limit (128 levels) standby mode for < 1 a current consumption 16 programmable fade - in and fade - out times (0. 1 s ec to 5.5 s ec ) with choice of square or cubic rates fading override i 2 c - compatible interface for all programming dedicated reset pin and built - in power - on reset (por) s hort - circuit, overvoltage, and overtemperature protection internal soft start to limit inrush currents inpu t- to - output isolation during faults or shutdown op erates down to v in = 2. 5 v , with undervoltage lockout (uvlo) at 2.0 v. available in a small , 2.15 mm 2.36 mm 0.6 mm wafer level chip scale package ( wl csp) or a 4 mm 4 mm 0.75 mm lead frame chip sca le package (lfcsp) a pplications mobile display backlighting mobile phone keypad backlighting rgb led lighting led indication general backlighting of small format displays typical operating ci rcuit 08829-001 d1 d2 d3 d4 d5 d6 d7 cmp_in v out optional photosensor photo- sensor v dd_als 0.1f 0.1f v in 1f gnd c2+ c2? c2 1f c1+ c1? c1 1f v out 1f ADP8870 n i n t pwm s d a s c l v dd i o n r st figure 1 . general description the adp 8870 combines a pr ogrammable backlight led charge - pump driver with automatic phototransistor control of the brightness (led current ) and a pwm in put to control the scale of the output current . this combination allows significant power savings because it automatically changes the current intensity based on the sensed ambient lighting levels and the display image content . it performs this function automatically , eliminating the need for a processor to monitor the photo - transistor. the light intensity thresholds are fully pro grammable via the i 2 c interface . the ADP8870 allows up to six leds to be independently driven up to 30 m a (maximum). an additional seventh led can be driven to 60 ma (maximum). all leds are individually programmable for minimum/maximum current and fade - in / fade - out times through an i 2 c interface. these leds can also be combined into groups to reduce the proce ssor instructions during fade - in and fade - out. driving these components is a two - capacitor charge pump with gains of 1, 1.5, and 2. this setup is capable of driving a maximum i out of 240 ma from a supply of 2.5 v to 5.5 v. a full suite of safety featu res , including short - circuit, overvoltage , and over temperature protection , allow s easy implementation of a safe and robust design. additionally, input inrush currents are limited via an integrated soft start combined with controlled input - to - output isolati on.
ADP8870 data sheet rev. b | page 2 of 60 table of contents features .............................................................................................. 1 applications ....................................................................................... 1 typical operating c ircuit ................................................................ 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications ..................................................................................... 3 absolute maximum ratings ............................................................ 6 maximum temperature ranges ................................................. 6 therm al resistance ...................................................................... 6 esd caution .................................................................................. 6 pin configurations and function descriptions ........................... 7 typical performance characteristics ............................................. 8 theory of operation ...................................................................... 12 power stage .................................................................................. 13 operating modes ........................................................................ 14 image content control .............................................................. 15 backlight operating levels ....................................................... 16 backlight maximum and dim settings ................................... 16 automated fade - in and fade - out ........................................... 17 backlight turn on/tur n off/dim ........................................... 17 automatic dim and turn off timers ..................................... 18 fade override ............................................................................. 18 backlight ambient light sensing ............................................. 19 d7 ambient light - sensing control ......................................... 20 automatic backlight adjustment ............................................. 20 independent sink control (isc) .............................................. 21 short - circuit protection (scp) mode ..................................... 21 overvoltage protection (ovp) ................................................. 21 thermal shutdown (tsd)/ overtemperature protection .... 21 interrupts ..................................................................................... 23 backlight off interrupt .............................................................. 23 applications information .............................................................. 24 layout guidelines ....................................................................... 24 example circuit .......................................................................... 25 i 2 c programming and digital control ........................................ 26 register summary .......................................................................... 28 register details ............................................................................... 29 manufacturer and device id (mfdvid) register 0x00 ... 29 mode control register (mdcr) register 0x01 .................. 29 interrupt status register (int_stat) register 0x02 ........ 30 interrupt enable ( int_en ) regist er 0x03 .......................... 30 backlight register descriptions ............................................... 31 independent sink register descriptions ................................. 4 0 comparator register descriptions .......................................... 50 outline dimensions ....................................................................... 56 ordering guide .......................................................................... 56 revision history 1/14 rev. a to rev. b change to figure 35 ....................................................................... 17 8/1 2 revision a : initial version
data sheet ADP8870 rev. b | page 3 of 60 specifications vin = 3.6 v, scl = 2.7 v, sda = 2.7 v, nint = open, nrst = 2.7 v, cmp_in = 0 v, v d1:d7 = 0.4 v, c1 = 1 f, c2 = 1 f, c out = 1 f, typical values are at t j = 25c and are not guaranteed, minimum and maximum limits are guaranteed from t j = ?40c to + 10 5c, unless otherwise noted. table 1. parameter symbol test conditi ons/comments min typ max unit supply input voltage operating range v in 2.5 5.5 v start - up level v in(start ) v in increasing 2.02 2.3 v low level v in(stop) v in decreasing 1.6 1.94 v v in(start ) hysteresis v in(hys) after startup 80 mv quiescent current i q during standby i q(stby) v in = 3.6 v, bit nstby = 0, scl = sda = 0 v 0.3 1.5 a i q active at gain = 1 i q(1 ) v in = 3.6 v, bit nstby = 1, i out = 0 ma 1.4 2.0 ma i q active at gain = 1.5 i q(1.5 ) v in = 3.6 v, bit nstby = 1, i out = 0 ma 3.9 5.1 ma i q active at gain = 2 i q(2 ) v in = 3.6 v, bit nstby = 1, i out = 0 ma 4.6 6.2 ma oscillator charge - pump gain = 2 switching frequency f sw 0.90 1.00 1.10 mhz duty cycle d 50 % ouput current control maximum drive current i d1:d7(max) v d1:d7 = 0.4 v d1 to d7 bit scr = 0 in the isc7 register t j = 25c 28.0 30.0 32.0 ma t j = ?40c to +10 5c 27.0 33.0 ma d7 (60 ma setting) i d7(60 ma) v d7 = 0.4 v, bit scr = 1 in the isc7 register t j = 25c 55.0 60.0 65.0 ma t j = ?40c to + 10 5c 52.5 67.0 ma led current source matching 1 i match v d1:d7 = 0.4 v 1 2.5 % leakage curr ent on led pins i d1:d7(lkg) v in = 5.5 v, v d1:d7 = 2.5 v, bit nstby=1 0.5 a equivalent output resistance r out gain = 1 v in = 3.6 v, i out = 100 ma 0.5 1.0 gain = 1.5 v in = 3.1 v, i out = 100 ma 3.0 gain = 2 v in = 2.5 v, i out = 100 ma 3.8 regulated output voltage v out(reg) v in = 3 v, gain = 2, i out = 10 ma 4.3 4.7 5.1 v automatic gain selection headroom voltage threshold for gain increase v hr(up) decrease v dx until the gain switches up 115 180 245 mv minimum current sink headroom voltage v hr(min) i dx = i dx(max) 95% 50 mv gain delay t gain the delay after gain has changed and before gain is allowed to change again 100 s ambient light - sensing comparators ambient light sensor current i als t j = 25c 1.05 1.10 1.15 ma t j = ?40c to +105c 1.00 1.20 ma
ADP8870 data sheet rev. b | page 4 of 60 parameter symbol test conditi ons/comments min typ max unit dac bit step threshold for level 2 i l2bit i l2bit = i als /250 4.4 a threshold for level 3 i l3bit i l3bit = i als /500 2.2 a threshold for level 4 i l4bit i l4bit = i als /1000 1.1 a thresh old for level 5 i l5bit i l5bit = i als /2000 0.55 a ambient light sensor threshold voltage v als 0.95 1.12 v pwm specifications v ddio voltage operating range v ddio 5.5 v logic low input 2 v pwmil v in = 2.5 v 0.5 v logic high input 3 v pwmih v in = 5.5 v 1.45 v minimum pwm clock frequency f pwm(min) 140 hz maximum pwm clock frequency f pwm(max) 60 khz pwm pulse width t pwm(min) pwm on time for valid detection of pwm input 2 s pwm to output current linearity maximum deviation in ou tput current vs . pwm duty cycle from 100% to 25% 1.4 % response time of pwm controlled output f pwm < 2 khz 1/f pwm sec response time of pwm controlled output f pwm > 2 khz 1.3 ms pwm accuracy blmx = 0x7f (30 ma), pwm duty cycle = 50% 1.0 % fau lt protection start - up charging current source i ss v in = 3.6 v, v out = 0.8 v in 3.5 7.0 11.0 ma output voltage threshold v out exit soft start v out(start) v out rising 0.92 v in v short - circuit protection v out(sc) v out falling 0.55 v i n v output overvoltage protection activation level v ovp 5.7 v thermal shutdown threshold tsd 150 c hysteresis tsd (hys) 20 c isolation from input to output during fault i outlkg v in = 5.5 v, v out = 0 v, bit nstby = 0 1 a time to v alidate a fault t fault 2 s i 2 c interface v ddio voltage operating range v ddio 5.5 v logic low input 2 v il v in = 2.5 v 0.5 v logic high input 3 v ih v in = 5.5 v 1.45 v i 2 c timing specifications guaranteed by design delay from reset deassertion to i 2 c access t reset 20 s scl clock frequency f scl 400 khz scl high time t high 0.6 s scl low time t low 1.3 s setup time d ata t su, dat 100 ns repeated start t su, sta 0.6 s stop condition t su, sto 0.6 s
data sheet ADP8870 rev. b | page 5 of 60 parameter symbol test conditi ons/comments min typ max unit hold time data t hd, dat 0 0.9 s start/repeated start t hd, sta 0.6 s bus - free time (stop and start conditions) t buf 1.3 s rise time (scl and sda) t r 20 + 0.1 c b 300 ns fall time (scl and sda) t f 20 + 0.1 c b 300 ns pulse width of suppressed spike t sp 0 50 ns capacitive load per bus line c b 400 pf 1 matching is calculated by dividing the difference between the maximum and minimum current from the sum of the maximum and min imum. 2 v il is a function of the v in voltage. see figure 19 in the typical performance characteristics section for typical values over operating ranges. 3 v ih is a function of the v in voltage. see figure 19 in the typical performance characteristics section for typical values over operating ranges. timing diagram sda scl s s = start condition sr = repeated start condition p = stop condition sr p s t low t r t hd, dat t high t su, dat t f t f t su, sta t hd, sta t sp t su, sto t buf t r 08829-002 figure 2 . i 2 c interface timing diagram
ADP8870 data sheet rev. b | page 6 of 60 absolute maximum rat ings table 2. parameter rating vin, vout to gnd ?0.3 v to +6 v d1, d2, d3, d4, d5, d6, and d7 to gnd ?0.3 v to +6 v cmp_in to gnd ?0.3 v to +6 v nint, nrst, scl, and sda to gnd ?0.3 v to +6 v output short - circuit duration indefinite operating ambient temperature range 1 ? 40c to +85c operating jun ction temperature range 1 ? 40c to +125c storage temperature range ? 65c to +150c soldering conditions jedec j - std -020 esd (electrostatic discharge) human body model (hbm) 2.0 kv charged device model (cdm) 1.5 kv 1 the maximum operating junction temperature (t j(max) ) supersedes the maximum operating ambient temperature (t a(max) ). see the maximum temperature ranges section for more information. stresses above those listed under absolute maximum ratings m ay cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum r ating conditions for extended periods may affect device reliability. absolute maximum ratings apply individually only, not in combination. unless otherwise specified, all voltages are referenced to gnd. maximum temperature ranges the maximum operating junc tion temperature (t j(max) ) supersedes the maximum operating ambient temperature (t a(max) ). therefore, in situations where the ADP8870 is exposed to poor thermal resistance and a high power diss ipation (p d ), the maximum ambient temperature may need to be derated. in these cases, the ambient temperature maximum can be calculated with the following equation: t a(max) = t j(max) ? ( ja p d(max) ). thermal resistance ja (junction to air) is specifie d for the worst - case conditions, that is, a device soldered in a circuit board for surface - mount packages. the ja , jb (junction to board), and jc (junction to case) are determined according to jesd51 - 9 on a 4 - layer printed circuit board (pcb) with natur al convection cooling. for the lfcsp package, the exposed pad must be soldered to gnd. table 3 . thermal resistance 1 package type ja jb jc unit wlcsp 48 9 n/a c/w lfcsp 49.5 n / a 5.3 c/w 1 n /a means not applicable. esd caut ion
data sheet ADP8870 rev. b | page 7 of 60 pin configurations a nd function descript ions 08829-003 1 d3 2 d2 3 d1 4 s c l 5 n r st 1 3 v o u t 1 4 v i n 1 5 g nd 1 2 c 2 + 1 1 c 1 + 6 n i n t 7 s d a 8 pwm 1 0 c 2 ? 9 c 1 ? 1 8 cmp_in 1 9 d5 2 0 d4 1 7 d6 1 6 d7 n o t es 1 . c o nn e c t t h e exp o se d p add l e t o g nd . t o p v i ew ( n o t t o s ca l e ) ad p 88 70 figure 3 . lfcsp pin configuration t op view (bal l side down) not to scale 08829-004 1 a b c d 2 3 4 bal l a1 indic a t or c1+ c1 ? c2+ pwm nrst vin d7 d6 cmp_in d1 d2 gnd d5 d4 d 3 vout sda c 2 ? nint scl e figure 4 . wlcsp pin configuration table 4 . pin function descriptions pin no. l fcsp wlcsp mnemonic description 14 a3 vin input voltage (2.5 v to 5.5 v). 3 d3 d1 led sink 1. 2 e3 d2 led sink 2. 1 e4 d3 led sink 3. 20 d4 d4 led sink 4. 19 c4 d5 led sink 5. 17 b4 d6 led sink 6 and optional comparator input for second phototransi stor. when this pin is used as a second phototransistor input, a capacitor (0.1 f recommended) must be connected from this pin to ground. 16 b3 d7 led sink 7. 18 c3 cmp_in comparator input for phototransistor. when this pin is used, a capacitor (0.1 f recommended) must be connected from this pin to ground. 13 a2 vout charge - pump output. 11 a1 c1+ charge - pump c1+. 9 c1 c1? charge - pump c1?. 12 b1 c2+ charge - pump c2+. 10 b2 c2? charge - pump c2?. 15 a4 gnd ground. 8 d1 pwm pwm input for led dimming . 6 d2 nint processor interrupt (active low). requires an external pull - up resistor. if this pin is not used, it can be left floating. 5 e1 nrst hardware reset (active low). this bit resets the device to the default conditions. if this pin is not used, it must be tied above v ih(max) . 7 c2 sda i 2 c serial data. requires an external pull - up resistor. 4 e2 scl i 2 c clock. requires an external pull - up resistor. ep ep exposed paddle. the exposed paddle must be connected to gnd.
ADP8870 data sheet rev. b | page 8 of 60 typical performance charac teristics vin = 3.6 v, scl = 2.7 v, sda = 2.7 v, nrst = 2.7 v, v d1:d7 = 0.4 v, c in = 1 f, c1 = 1 f, c2 = 1 f, c out = 1 f, t a = 25c, unless otherwise noted. 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) i q (ma) 08829-034 i out = 0ma +25c ?40c +85c +105c figure 5 . typical operating current, g = 1 5.0 4.0 3.0 2.0 1.0 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) i q (ma) 08829-035 +25c ?40c +85c +105c i out = 0ma figure 6 . typical operating current, g = 1.5 5.0 4.0 3.0 2.0 1.0 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) 08829-036 +25c ?40c +85c +105c i out = 0ma i q (ma) figure 7 . typical operating current, g = 2 100 10 1 0.1 0.01 0.001 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) i q (a) 08829-037 +25c ?40c +85c +105c scl = sda = 0v figure 8 . typical standby i q 35 33 34 31 32 29 30 27 28 25 26 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) led current (ma) 08829-038 +25c ?40c +85c +105c v d1:d7 = 0.4v figure 9 . typical diode current vs. v in 5.0 4.0 4.5 3.0 3.5 2.0 2.5 1.0 1.5 0 0.5 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 v hr (v) matching (%) 08829-039 +25c ?40c +85c +105c i d1:d7 = 30ma figure 10 . typical diode matching vs. current sink headroom voltage (v hr )
data sheet ADP8870 rev. b | page 9 of 60 35 30 20 25 15 10 0 5 0.2 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 v hr (v) i out (ma) 08829-040 +25c ?40c +85c +105c +25c ?40c +85c +105c i out set to 30ma (code 0x7f) i out set to 18.23ma (code 0x63) figure 11 . typical diode current vs. current sink headroom voltage (v hr ) 2.0 1.5 0.5 1.0 0 ?0.5 ?2.0 ?1.0 ?1.5 ?40 ?20 0 20 40 60 80 100 temperature (c) i out deviation (%) 08829-041 v d1:d7 = 0.4v figure 12 . typical change in diode current vs. temperature 30 25 20 15 0 10 5 0 20 40 60 80 100 duty cycle (%) i led (ma) 08829-042 +25c ?40c +85c +105c figure 13 . pwm current scaling across temperature 30 25 20 15 0 10 5 0 20 40 60 80 100 duty cycle (%) i led (ma) 08829-043 32khz 200hz 5khz 60khz figure 14 . pwm current scaling across pwm frequency 1.0 0.9 0.8 0.7 0 0.6 0.4 0.3 0.2 0.1 0.5 2.5 3.0 3.5 4.0 4.5 5.0 v in (v) r out (1) (?) 08829-044 +25c ?40c +85c +105c i out = 100ma figure 15 . typical r out (g = 1) v s. v in 6 5 4 3 0 2 1 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 v in (v) r out (1.5) (?) 08829-045 +25c ?40c +85c +105c i out = 100ma figure 16 . typical r out (g = 1.5) vs. v in
ADP8870 data sheet rev. b | page 10 of 60 6 5 4 3 0 2 1 2.20 2.25 2.30 2.35 2.40 2.45 2.50 2.55 2.60 2.65 2.70 v in (v) r out (2) (?) 08829-046 +25c ?40c +85c +105c i out = 100ma figure 17 . typical r out (g = 2 ) vs. v in 20 16 18 12 14 8 10 4 6 0 2 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) i ss (ma) 08829-047 +25c ?40c +85c +105c v out = 80% of v in figure 18 . ty pical output soft start current ( i ss ) 1.4 1.0 1.2 0.6 0.8 0.2 0.4 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) threshold (v) 08829-048 v il , +25c v ih , +25c v il , ?40c v ih ,?40c v il ,+85c v ih ,+85c v il ,+105c v ih ,+105c figure 19 . typical i 2 c thre sholds ( v ih and v il ) 1.14 1.16 1.18 1.20 1.10 1.12 1.06 1.08 1.02 1.04 1.00 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) i als (ma) 08829-049 +25c ?40c +85c +105c i out = 100ma figure 20 . typical als current ( i als ) 60 70 80 90 50 30 40 10 20 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) efficiency (%) 08829-050 v f = 4.1v v f = 3.5v v f = 3.2v figure 21 . typical efficiency ( seven led s , 30 ma per led ) 60 70 80 90 50 30 40 10 20 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) efficiency (%) 08829-051 v f = 3.6v v f = 3.2v figure 22 . typical effi ciency ( seven leds, 18 ma per led )
data sheet ADP8870 rev. b | page 11 of 60 08829-052 1s/div 1 2 3 v in (ac-coupled) 50mv/div v out (ac-coupled) 50mv/div i in (ac-coupled) 10ma/div t c in = 1f, c out = 1f, c1 = 1f, c2 = 1f v in = 3.6v i out = 120ma figure 23 . typical operating waveforms, g = 1 08829-053 1s/div 1 2 3 v in (ac-coupled) 50mv/div v out (ac-coupled) 50mv/div i in (ac-coupled) 10ma/div t c in = 1f, c out = 1f, c1 = 1f, c2 = 1f v in = 3.0v i out = 120ma figure 24 . typical operating waveforms, g = 1.5 08829-054 1s/div 1 2 3 v in (ac-coupled) 50mv/div v out (ac-coupled) 50mv/div i in (ac-coupled) 10ma/div t c in = 1f, c out = 1f, c1 = 1f, c2 = 1f v in = 2.5v i out = 120ma figure 25 . typical operating waveforms , g = 2 08829-055 100s/div 2 4 i in (10ma/div) v out (1v/div) i out (10ma/div) t 3 c in = 10f, c out = 1f, c1 = 1f, c2 = 1f v in = 3.6v figure 26 . typical start - up waveforms
ADP8870 data sheet rev. b | page 12 of 60 theory of operation the ADP8870 combines a programmable backlight led charge - pump driver with automatic phototran sistor brightness control (led current ) and a pwm input to control the scale of the output current. this combination allows significant power savings because it automatically changes the current intensity based on the sensed ambient lighting levels and the display image content. it performs this function automatically and , therefore , removes the need for a processor to monitor the phototransistor. the light intensity thresholds are fully programmable via the i 2 c interface. a second phototransistor input, w ith dedicated comparators, improves the ambient light detection abilities for various operating conditions. the ADP8870 allows up to seven leds to be independently driven up to 30 ma (typical ). t he seventh led can be driven an additional 30 ma, for a maximum of up to 60 ma (typical). all leds can be individually programmed or combined into a group to operate backlight leds. a full suite of safety features , including short - circuit, overvoltage, a nd overtemperature protection with input - to - output isolation , allow for a robust and safe design. the integrated soft start limits inrush currents at startup, restart attempts, and gain transitions. n i n t pwm vo u t v i n st ndb y en v i n v ba t vin c 1 + sd a sc l vdd i o st ndb y i l ed c o n t r o l i d 1 i d 2 i d 3 i d 4 i d 5 i d 6 i d 7 scale c 1 ? c 2 + c 2 ? gnd n r st n oi se f i lter 50 s r eset d2 d3 d4 d5 d6 d7 cmp_in d1 i d 1 i d 2 i d 3 i d 4 i d 5 i d 6 i d 7 soft start optional photosensor c l k u vl o 08829-005 v r e f i r e f c out i s s v in g a i n sel ec t l ogi c char g e- pu mp l ogi c light sensor logic photosensor conversion char g e pu mp (1 , 1 . 5 , 2 ) c 1 1 f c 2 1 f i 2 c l ogi c v dd_als pwm filter led output current c i n figure 27 . detailed block di agram
data sheet ADP8870 rev. b | page 13 of 60 power stage because typical white leds require up to 4 v to drive them, some form of boosting is required over the typical variation in battery voltage. the ADP8870 accomplishes this with a high efficiency charge pump capable of producing a maximum i out of 240 ma over the entire input voltage range (2.5 v to 5.5 v). charge pumps use the basic principle that a capacitor stores charge based on the voltage applied to it, as shown in the following equation: q = c v (1) by charging the capacitors in different configurations, the charge, and hence the gain, can be optimized to deliver the voltage required to power the leds. because a fixed charging and discharging combination must be used, only certain multiples of gain are available. the ADP8870 is capable of automatically optimizing the gain (g) from 1, 1.5, and 2. these gains are accomplished with two capacitors and an internal switching network. in g = 1 mode, the switches are configured to pass vin directly to vout. in this mode, several switches are connected in parallel to minimize the resistive drop from input to output. in g = 1.5 and g = 2 modes, the switches alternatively charge from the battery and discharge into the output. for g = 1.5, the capacitors are charged from vin in series and are discharged to vout in parallel. for g = 2, the capacitors are charged from vin in parallel and are discharged to vout in parallel. in certain fault modes, the switches are opened and the output is physically isolated from the input. automatic gain selection each led that is driven requires a current source. the voltage on this current source must be greater than a minimum headroom voltage (225 mv typical) to maintain accurate current regulation. the gain is automatically selected based on the minimum voltage (v dx ) at all of the current sources. at startup, the device is placed into g = 1 mode and the output charges to v in . if any v dx level is less than the required headroom (200 mv), then the gain is increased to the next step (g = 1.5 ). a 100 s delay is allowed for the output to stabilize prior to the next gain switching decision. if there remains insufficient current sink headroom, then the gain is increased again to 2. conversely, to optimize efficiency, it is not desirable for the output voltage to be too high. therefore, the gain reduces when the headroom voltage is great enough. this point (labeled v d(max) in figure 28) is internally calculated to ensure that the lower gain still results in ample headroom for all the current sinks. the entire cycle is illustrated in figure 28. 08829-006 notes 1. v d(max) is the calculated transition point at which gain is reduced. wait 100s (typ) v d1:d7(min) < v hr(up) 0 0 1 1 1 1 0 0 start-up: charge v in to v out exit stby vout > v out(start) 1 wait 100s (typ) wait 100s (typ) v d1:d7(min) < v hr(up) v d1:d7(min) > v d(max) v d1:d7(min) < v d(max) g = 2 g = 1.5 exit startup g = 1 stby 0 figure 28. state diagram for automatic gain selection
ADP8870 data sheet rev. b | page 14 of 60 note that the gain selection criteria apply only to active current sources. if a current source has been deactivated through an i 2 c command (that is, if only five leds are u sed for an application), the voltages on these current sources are ignored. soft start feature at startup (either from uvlo activation or fault/standby recovery), the output is first charged by i ss ( 7.0 ma typical) until it reaches about 92% of v in . this soft start feature reduces the inrush current that is otherwise present when the output capacitance is initially charged to v in . when this point is reached, the controller enters 1 mode. if the output voltage is not sufficient, then the automatic gain sel ection determines the optimal point as described in the automatic gain selection section. operating modes there are four different operating modes: active, standby, shutdown, and reset. active mode in active mode , all circuits are powered up and in a fully operational state. this mode is entered when nstby (in register mdcr) is set to 1. standby mode standby mode disables all circuitry except the i 2 c receivers. current consumption is reduced to less than 1 a. t his mode is entered when nstby is set to 0 or when the nrst pin is held low for more than 100 s (maximum). when standby is exited, a soft start sequence is performed. shutdown mode shutdown mode disables all circuitry, including the i 2 c receivers. shutdo wn occurs when v in is below the undervoltage thresholds. when v in rises above v in(start) (2.0 2 v typical), all registers are reset and the part is placed into standby mode. reset mode in reset mode, all registers are set to their default values and the pa rt is placed into standby. there are two ways to reset the part: power - on reset (por) and the nrst pin. por is activated any - time that the part exits shutdown mode. after a por sequence is complete, the part automatically enters standby mode. after startu p, the part can be reset by pulling the nrst pin low. as long as the nrst pin is low, the part is held in a standby state but no i 2 c commands are acknowledged (all registers are kept at their default values). after releasing the nrst pin, all registers rem ain at their default values, and the part remains in standby; however, the part does accept i 2 c commands. the nrst pin has a 50 s (typical) noise filter to prevent inad - vertent activation of the reset function. the nrst pin must be held low for this entire time to activate a reset. the operating modes function according to the timing shown in figure 29. vin ns t b y n r st vout v i n s hu t d o w n n r s t m u s t b e h ig h f o r 20 s (m a ximum) b e f o r e se nd i n g i 2 c c o mm and s bit n s t by in register mdcr is set high by the user n r s t i s l o w , w h i ch f o rc es ns t b y l o w and r ese t s a ll i 2 c r e gi s t e r s ~ 100 s d e l a y b e tw ee n p o w e r - u p an d w h e n i 2 c c o mm and s can b e r e c e i ved ~9.5 m a char g es v o u t t o v i n l evel 25 s t o 100 s n oi se f i lt er 1 1 . 5 2 s o ft s t ar t s o ft s t ar t 10 s 100 s 08829-007 g a i n chan g es o n l y o ccur w h e n n e c ess ar y, bu t ha ve a m i n imum t i me b e f o r e chan gi n g v i n cr o sses ~ 2 . 05 v and t r igg e r s a p o w e r - o n r eset figure 29 . typical timing diagram
data sheet ADP8870 rev. b | page 15 of 60 image content contro l modern lcd display drivers often output the white intensity of the displayed image in the form of a pwm signal. when the white content of the displaye d image is very small, the lcd driver generates a pwm duty cycle that is large. the ADP8870 takes advantage of this feature by incorporating a pwm input pin that scales the backlight intensity. when the pwm signal is at 100% duty cycle, the backlight current function s at its programmed va lue . however, when the pwm duty cycle drops, the ADP8870 automatically scales the output led curr ent down . 100% iled 100% pwm dut y 08829-008 figure 30 . output current response to pwm input duty cycle the leds that respond to the pwm input can be selected in the pwmled register (register 0x06) . this image content works naturally with the automatic ambient li ght sensing and the three gain s of the charge pump (see figure 31 ). 08829-009 on/off max current bias dac boost i 2 c dimming control light sensor pwm image content 1f lcd displ a y image content figure 31 . functional overview of the pwm image content control, ambient light sensor, and charge pump dimming profile 08829-010 sensor tri p point outdoor office dark office led current image content f ade-in f ade-out figure 32 . example led output current with the effects of the image content pwm and ambient light sensing
ADP8870 data sheet rev. b | page 16 of 60 backlight operating levels backlight brightness control can operate in five distinct levels: daylight (l evel 1), bright ( level 2), office ( level 3), i ndoor ( level 4) , and dark ( level 5) . the blv bits in register 0x04 control the specific level in which the backlight operates. these bits can be changed manually, or if in automatic mode ( that is, when cmp_autoen is set high in register 0x01), by the ambie nt light sensor (see the d7 ambient light - sensing control section). by default, the backlight operates at daylight level (blv = 0 0 0), where the maximum brightness is set using register 0x0 a (blmx1). a daylight dim setting can als o be se t using register 0x0 b (bldm1). similarly, w hen operating at the bright , office, indoor, or dark level , the correspon ding register is used (register 0x0 c to register 0x1 3 ). backlight maximum an d dim settings the backlight maximum and dim current set tings are deter - mined by a 7 - bit code programmed by the user into the registers previously listed in the image content control section . the 7 - bit resolution allows the user to set the backlight to one of 128 different levels betwe en 0 ma and 30 ma. the ADP8870 implements a square law algorithm to achieve a nonlinear relationship between input code and backlight current. t he backlight current (in milliamperes) is determi ned by the following equation: 2 127 ) ma ( ? ? ? ? ? ? ? ? ? = current scale full code current backlight ( 2 ) where: code is the input code programmed by the user. full - scale current is the maximum sink current allowed per led (typically 30 ma). figure 34 shows t he backlight current level vs. input code . bright ( l evel 2 ) office ( l evel 3 ) indoor ( l evel 4) dark ( l evel 5) back l ig h t o per a t i n g l eve l s backlight current d a y l ig h t d i m d a y l ig h t m a x bright m a x office m a x office d i m bright d i m 0 30 m a indoor m a x dark m a x dark d i m indoor d i m 08829-011 day l ig h t ( l evel 1 ) figure 33 . backlight operating level 30 25 20 15 10 5 0 0 32 64 96 128 sink code backlight current (ma) 08829-012 figure 34 . backlight current vs. sink code
data sheet ADP8870 rev. b | page 17 of 60 automated fad e - in and fade - out the led drivers are easily configured for automated fade - in and fade - out . sixteen fade - in and fade - out rates can be selected via the i 2 c interface. fade - in and fade - out rates range from 0.1 sec to 5.5 sec (per full - scale current, either 30 ma or 60 ma). the bloff_int bit (register 0x02) can be us ed to flag the interrupt pin when an automated backlight fade - out occur s (see the interrupts section) . table 5 . available fade - in and fade - out times code fade rate (sec ) 0000 0.1 (disabled) 0001 0.3 0010 0.6 0011 0.9 0100 1.2 0101 1.5 0110 1.8 0111 2.1 1000 2.4 1001 2.7 1010 3.0 1011 3.5 1100 4.0 1101 4.5 1110 5.0 1111 5.5 the fade profile is based on the transfer law selected (square, cubic 10, or cubic 11) and the delta bet ween the actual current and the target current. smaller changes in current reduce the fade time. for square law fades, the fade time is given by fade time = fade rate ( code /127) ( 3 ) where the fade rate is as shown in table 5 . t he cubic 10 and cubic 11 laws also use the square backlight currents in equation 3; however, the time between each step is varied to produce a steeper slope at higher currents and a shallower slope at lighter currents (see figure 35 ). 30 0 5 10 15 20 25 0 1.00 0.75 0.50 0.25 current (ma) unit fade time square cubic 11 cubic 10 08829-013 figure 35 . comparison of the dimming transfers laws backlight turn on/tu rn off/dim with the device in active mode ( n stby = 1), the backlight can be turned on using the bl_en bit in register 0x0 1 . before t urning on the backlight, the user chooses which level ( daylight, bright, office, indoor, or dark ) in which to operate and ensures that maximum and dim settings are programmed for that level. the backlight turns on when bl_en = 1. the backlight turns off wh en bl_en = 0. maximum bl_en = 1 bl_en = 0 backlight current 08829-014 figure 36 . backlight turn on/ turn off while the backlight is on (bl_en = 1), the user can make it change to a dim setting by programming dim_en = 1 in register 0x0 1 . if dim_en = 0, then the backlight reverts to its maximum setting. maximum dim bl_en = 1 dim_en = 1 dim_en = 0 bl_en = 0 backlight current 08829-015 figure 37 . backlight turn on/dim/turn off the maximum and dim settings can be set between 0 ma and 30 ma; therefore, it is possible to program a dim setting that is greater than a maximum setting. for normal expe cted operation, ensure that the dim setting is programmed to be less than the maximum setting.
ADP8870 data sheet rev. b | page 18 of 60 automatic dim and turn off timers the user can program the backlight to dim automatically by using the dimt timer in register 0x08. the dim timer has 127 settings, ranging from 1 sec to 127 sec. program the dim timer before turning on the backlight. if bl_en = 1, the backlight turns on to its maximum setting and the dim timer starts counting. when the dim timer expires, the internal state machine sets dim_en = 1, and the backlight enters its dim setting. maximum dim backlight current dim timer running dim timer running 08829-016 bl_en = 1 dim_en = 1 dim_en = 1 set by user set by internal state machine bl_en = 0 dim_en = 0 or bl_en = 1 figure 38. dim timer if the user clears the dim_en bit (or reasserts the bl_en bit), the backlight reverts to its maximum setting and the dim timer begins counting again. when the dim timer expires, the internal state machine again sets dim_en = 1, and the backlight enters its dim setting. reasserting bl_en at any point during the dim timer countdown causes the timer to reset and resume counting. the backlight can be turned off at any point during the dim timer countdown by clearing bl_en. the user can also program the backlight to turn off automati- cally by using the offt timer in register 0x07. the off timer has 127 settings, ranging from 1 sec to 127 sec. program the off timer before turning on the backlight. if bl_en = 1, the backlight turns on to its maximum setting and the off timer starts counting. when the off timer expires, the internal state machine clears the bl_en bit, and the backlight turns off. maximum backlight current off timer running 08829-017 set by user set by internal state machine bl_en = 1 bl_en = 0 figure 39. off timer reasserting bl_en at any point during the off timer countdown causes the timer to reset and resume counting. the backlight can be turned off at any point during the off timer countdown by clearing bl_en. the dim timer and off timer can be used together for sequential maximum-to-dim-to-off functionality. with both the dim and off timers programmed, if bl_en is asserted, the backlight turns on to its maximum setting. when the dim timer expires, the backlight changes to its dim setting. when the off timer expires, the backlight turns off. maximum dim bl_en = 1 bl_en = 0 dim_en = 1 backlight current dim timer running off timer running set by user set by internal state machine 08829-018 figure 40. dim timer and off timer used together fade override a fade override feature (fovr in register cfgr (address 0x04)) enables the host to override the preprogrammed fade-in or fade-out settings. if fovr is set and the backlight is enabled in the middle of a fade-out process, the backlight instantly (within approximately 100 ms) returns to its prefade brightness level. alternatively, if the backlight is fading in, reasserting bl_en overrides the programmed fade-in time and the backlight instantly goes to its final fade value. this is useful for situations where a key is pressed during a fade sequence. alternatively, if fovr is cleared and the backlight is enabled in the middle of a fade process, the backlight fades in from where it was interrupted (that is, it does not go down to 0 and then come back on). maximum backlight current bl_en = 1 bl_en = 0 bl_en = 1 bl_en = 0 bl_en = 1 (reasserted) fade-in overridden fade-out overridden 08829-019 figure 41. fade override function (fovr is high)
data sheet ADP8870 rev. b | page 19 of 60 backlight ambient light sensin g the ADP8870 integrates two ambient light - sensing comparators. one of the ambient light sensing comparators (cmp_in) is always available. the second one (cmp_in2) can be activated instead of having an led conne cted to d6. activating cmp_in2 is accomplished through bit cmp2_sel in register cfgr. there - fore, when bit cmp2_sel is set to 0, pin d6 is programmed as a current sink. when bit cmp2_sel is set to 1, pin d6 becomes the input for a second phototransistor. t hese comparators have four programmable trip points ( l evel 2, l evel 3, l evel 4 , and l evel 5 ) that can be used to select between the five backlight opera ti n g modes (daylight, bright, office, indoor, and dark) based on the ambient lighting conditions. the l evel 5 comparator controls the dark - to - indoor mode tran - sition. the l evel 4 comparator controls the indoor - to - office transition. the l evel 3 comparator controls the office - to - bright transition. the l evel 2 comparator controls the bright - to - outdoor transiti on (see figure 42 ). the currents for the different lighting modes are defined in the blmxx and bldmx registers (see the backlight operating levels section). l2_tr p + l2_hys l2_tr p l4_tr p + l4_hys l4_tr p l5_tr p + l5_hys l5_tr p l3_tr p + l3_hys l3_tr p da ylight 0000 bright 0001 office 001x indoor 01xx dark 1xxx light intensit y (pho t osensor current) time 08829-020 figure 42 . light sensor modes are based on the ambient light level detected each light sensor comparator uses an external capacitor together with an internal reference current source to form an analog - to - digital converter (adc) that samples the output of the external photosensor. the adc result is fed into four programmable trip comparators. the adc has an input range of 0 a to 1100 a (typical). l2_hys l2_tri p l3_tri p l3_hys fi l ter settings adc pho t o sensor output l2_en l3_en l2_out l3_out 08829-033 l4_hys l4_tri p l5_tri p l5_hys l5_en l5_cmpr l4_cmpr l3_cmpr l2_cmpr l4_en l4_out l5_out figure 43 . ambient light - sensing and trip comparators each level comparator detects wh en the photosensor output has dropped below the programmable trip point ( defined in register 0x 32, register 0x 34, register 0x 36 , and register 0x 38 ). if this event occurs, then the corresponding level output status signal is set in register 0 x 30 and registe r 0x31 . each level comparator contains programmable hysteresis, meaning that the photosensor output must rise above the trip threshold plus the hysteresis value before the level output clears. each level is enabled via a corresponding bit in the als1_en ( a ddress 0x 2e ) and als2_en ( address 0x 2f ) registers . the l2_trp and l2_hys values of l evel 2 comparator can be set between 0 a and 1100 a (typical) in steps of 4.4 a (typical). the l 3 _trp and l3 _hys values of l evel 3 comparator can be set between 0 a and 550 a (typical) in steps of 2.2 a (typical). the l 4 _trp and l4_hys values of l evel 4 comparator can be set between 0 a and 275 a (typical) in steps of 1.1 a (typical). the l5 _trp and l 5 _hys values of l evel 5 comparator can be set between 0 a and 13 7 a (typical) in steps of 0.55 a (typical).
ADP8870 data sheet rev. b | page 20 of 60 l 2_ t r p l 2_ h ys l 5_ t r p l 5_ h ys 137 275 550 1100 adc ran g e ( a ) l 4_ t r p l 4_ h ys l 3_ t r p l 3_ h ys 08829-021 figure 44 . comparator ranges it is important to note that the full - scale value of the l2_trp and l2_hys registers is 250 d. therefore, if the value of l2_trp + l2_hys exceeds 250 d, th e comparator output cannot deassert. for example, if l2_trp is set at 204 d (80% of the full - scale value, or approximately 0.80 1122 a = 898 a), then l2_hys must be set at less than 46 d (250 ? 204 = 46). if it is not, then l2_hys + l2_trp exceed s 250 d and the l evel 2 comparator is not allowed to go low. when both phototransistors are enabled and progra mmed in automatic mode , the user application needs to determine which of the comparator outputs to use, selecting via bit sel_ab in register 0x04 for automatic light sensing transitions. for example, the users software might select the comparator of the phototransistor exposed to higher light intensity to control the transition between the programmed backlight intensity levels. the level comparat ors c an be enabled independent of each other or can operate simultaneously. a single conversion from each adc takes 80 ms (typical). when set for automatic backlight adjustment (see the automatic backlight adjustment se ction), the adc and comparators run continuously. if the backlight is disabled, it is possible to use the light sensor comparators in a single - shot mode. a single - shot read of the photocomparators is performed by setting the force_rd bit (register 0x2d) . a fter the single shot measurement is completed, the internal state machine clears the force_rd bit. interrupt flag cmp_int (register 0x02) is set if any of the level output status bits change state for the main photosensor input. this means that interrupts can be generated if ambient light conditions transition between any of the programmed trip points. cmp_int can cause the nint pin to be asserted if the cmp_ien bit (register 0x03) is set. the cmp_int flag can only be cleared by writing a 1 to it or resetti ng the part. the operation of cmp2_int (register 0x02) and cmp2_ien (register 0x03) is similar except that the second phototransistor ( that is, cmp_in2) is used. d7 ambient light - sensing control led d7 can be pro grammed to operate independent from the b acklight reset when under als control. this is useful when d7 is used to c ontrol peripheral lighting (for example, the keypad) that needs to respond differently than the backlight lighting. this feature uses the same als controls and thresholds as the back light. to engage d7 als control , first program the five als levels of d7 found in register 0x2 5 to register 0x2 9 . then set bit d7als_ en in register 0x01 and bit d7sel in register 0x05. backlight current d7 current l4 l5 l3 l2 indoor dark led output current office bright d a ylight 08829-022 figure 45 . a possible example of the separ ate als control of d7 automatic backlight adjustment the ambient light sensor comparators can be used to automati - cally transition the backlight between one of its three operating levels. to enable this mode, set the cmp_autoen bit in register 0x01. when enabled, the internal state machine takes control of the blv bits and changes them based on the level output status bits. table 6 shows the relationship between backlight operation and the ambient light sensor com parator outputs. the higher numbered level output status bit ha ve greater priority over the lower numbered levels. filter times between 80 ms and 10 sec can be p rogrammed for the comparators (r egister 0x 2 d ) before they change state. table 6 . comparator output truth table 1 l5_out l4_out l3_out l2_out als level blv code 1 x x x dark 100 0 1 x x indoor 011 0 0 1 x office 010 0 0 0 1 bright 001 0 0 0 0 outdoor 000 1 x is the dont care bit.
data sheet ADP8870 rev. b | page 21 of 60 independent sink con trol (isc) each of the 7 leds can be configured (in register 0x05) to operate as either part of the backlight or to operate as an independent sink current (isc). each isc can be enabled independently and has its own current level. all iscs share the same fade - in times, fade - out times, and fade law. the iscs have additional timers to facilitate blinking functions. a shared on timer (scon), used in conjunction with the off timers of each isc (sc1off, sc2off, sc3off, sc4off, sc5off, sc6off, and sc7off) , allow the led current s inks to be configured in various blinking modes. the on timer can be set to four settings: 0.2 sec, 0.6 sec, 0.8 sec, and 1.2 sec. the off timers also have four settings: disabled, 0.6 sec, 0.8 sec, and 1.2 sec. blink mode is activated by setting the off t imers to any setting other than disabled. program all fade, on, and off timers before enabling any of the led current sinks. if iscx is on during a blink cycle and scx_en is cleared, it turns off (or fades to off if fade - out is enabled). if iscx is off du ring a blink cycle and scx_en is cleared, it stays off. m a ximum f ad e- i n f ad e- o u t f ad e- i n f ad e- o u t o n t i me o n t i me 08829-023 iscx curr e n t o f f t i me o f f t i me set b y user scx_en figure 46 . ledx blink mode with fading short - circuit protection ( scp) mode the ADP8870 can protect against sh ort circuits on the output (v out ). short - circuit protection (scp) is activated at the point when v out < 55% of v in . note that this scp sensing is disabled during startup and restart attempts (fau lt recovery). scp sensing is re enabled 4 ms (typical) after a ctivation. during a short - circuit fault, the device enters a low current consumption state and an interrupt flag is set. the device can be restart at any time after receiving a short - circuit fault by simply rewriting nstby = 1. it then repeats another comp lete soft start sequence. note that the value of the output capacitance (c out ) should be small enough to allow v out to reach approximately 55% (typical) of v in within the 4 ms (typical) time. if c out is too large, the device inadvertently enter s short - circ uit protection. overvoltage protecti on (ovp) overvoltage protection is implemented on the output. there are two types of overvoltage events: normal (no fault) and abnormal. normal (no fault) overvoltage the output voltage approaches v out(reg) (4. 7 v typic al) during normal operation. this is not caused by a fault or load change, but simply a consequence of the input voltage times the gain reaching the clamped output voltage v out(reg) . to prevent this, the ADP8870 detects when the output voltage rises to v out(reg ) . it then increases the effective r out of the gain stage to reduce the voltage that is delivered. this effectively regulates v out to v out(reg) ; however, there is a limit to the effect tha t this system can have on regulating v out . it is designed only for normal operation and is not intended to protect against faults or sudden load changes. during this mode, no interrupt is set and the operation is transparent to the leds and overall applica tion. the automatic gain selection equations take into account the additional drop within r out to maintain optimum efficiency. abnormal (fault/sudden load change) overvoltage due to the open loop behavior of the charge pump as well as how the gain transiti ons are computed, a sudden load change or fault can abnormally force v out beyond 6 v. if the event happens slowly enough, the system first tries to regulate the output to 4.7 v (typical) as in a normal overvoltage scenario. however, if this is not sufficie nt, or if the event happens too quickly, then the ADP8870 enters overvoltage protection mode when v out exceeds the ovp threshold (typically 5. 7 v). in this mode, the charge pump is disabled to prevent v out from rising too high. the current sources and all other device functionality remain intact. when the output voltage falls below the ovp threshold, the charge pump resumes operation. if the fault or load step recurs, the process may repeat. an interrupt flag is set at each ovp instance. thermal shutdown (ts d)/ overtemperature prot ection if the die temperature of the ADP8870 rises above a safety limit (150c typical), the controllers enter tsd protection mode. in this mode, most of the internal functions are shut down, the part enters standby, and the tsd_int interrupt (register 0x02) is set. when the die temperature decreases below ~130c, the part is allowed to be restarted. to rest art the part, simply remove it from standby. no interrupt is generated when the die temperature falls below 130c. however, if the software clears the pending tsd_int interrupt and the temperature remains above 130c, another interrupt is generated. the co mplete state machine for these faults (scp, ovp, and tsd) is shown in figure 47.
ADP8870 data sheet rev. b | page 22 of 60 08829-024 wait 100s (typ) g = 1.5 0 0 1 1 1 1 0 vout > v ovp 1 0 1 0 v out > v out(reg) try to regulate vout to v out(reg) vout > v ovp ovp fault vout < v ovp 0 1 0 1 1 0 vout > v ovp 0 1 0 1 1 0 exit startup g = 1 stby 1 0 vout < v out(sc) 0 scp fault exit stby start-up: charge v in to v out v out > v out(start) v out < v out(sc) die temp > tsd 0 tsd fault die temp < tsd ? tsd (hys) v d1:d7(min) < v hr(up) v d1:d7(min) < v hr(up) v d1:d7(min) > v d(max) v d1:d7(min) > v d(max) 1 0 exit stby vout < v ovp v out > v out(reg) notes 1. v d(max) is the calculated transition point at which gain is reduced. vout < v ovp 1 0 ovp fault try to regulate vout to v out(reg) g = 2 wait 100s (typ) wait 100s (typ) ovp fault figure 47. fault state machine
data sheet ADP8870 rev. b | page 23 of 60 interrupts there are six interrupt sources available on the ADP8870 (in register 0x02) . ? backlight off : at the end of each automated backlight fade - out , this interrupt (bloff_int) is set. ? main light sensor comparator: cmp_int sets every time the main light sensor comparator detects a threshold ( l evel 2, level 3, level 4, or level 5 ) transition (rising or falling conditions). ? sensor comparator 2: cmp2_int interrupt works the same way as cmp_int, except that the sensing input is coming from the second light sensor. the programmable threshold is the same as the main light sensor comparator. ? overvoltage protection: ovp_int is generated when the output voltage exceeds 5. 7 v (typical). ? thermal shutdown circuit: an interrupt (tsd_int) is generated when entering overtempe rature protection. ? short - circuit detection: short_int is generated when the device enters short - circuit protection mode. the interrupt (if any) that appears on the nint pin is determined by the bits mapped in register int_en . to clear an interrupt, write a 1 to the interrupt in the int_stat register or reset the part. backlight off interr upt the backlight off interrupt (bloff_int) is set when the backlight completes an automated fade sequence. this could be a simple fade - out command or a complete dimming profile. this feature is useful to synchronize the backlight turn off with the lcd display driver. backlight current f ade-in: off t o maximum f ade-ou t : maximum t o dim f ade-ou t : dim t o off maximum dim 08829-025 set b y user set b y interna l s ta te machine bloff_int set bl_en = 1 bl_en = 0 dim_en = 1 figure 48 . end of fade - out (eof) interrupt as used for a backlight fade - out (set by user) dim timer running f ade-out f ade-out maximum dim 08829-026 backlight current off timer running f ade-in bloff_int set set b y user set b y interna l s ta te machine bl_en = 1 bl_en = 0 dim_en = 0 dim_en = 1 figure 49 . en d of fade - out (eof) interrupt as used for a n automated dim profile ( set by internal state machine )
ADP8870 data sheet rev. b | page 24 of 60 applications informa tion the ADP8870 allows the charge pump to operate efficiently with a m inimum of external components , requiring only an input capacitor (c in ), an output capacitor (c out ), and two charge - pump fly capacitors (c1 and c2). c in should be 1 f or greater , and c out, c1, and c2 should each be 1 f . although in some cases other values can be used, keep in mind the following: ? the value of c in must be high enough to produce a stable input voltage signal at the minimum input voltage and maximum output load. ? values larger than 1 f are permissible for c out , but care must be exercised to ensure that v out charges above 55% (typ) of v in within 4 ms (typ). see the short - circuit protection (scp) mode section for more detail s. ? v alues larger than 1 f for c1 and c2 are not recommended , and smaller values may reduce the ability of the charge pump to deliver maximum current. furthermore, f or optimal efficiency, the charge - pump fly capacitors should have low equivalent series resistance (esr). low esr x5r or x7r capacitors are recommended for all four components. the use of fly capacitors sized 0402 and smaller is allowed, but the gdwn_dis bit in register 0x01 must be set. mini mum voltage ratings should adhere to the guidelines in table 7 . table 7 . capacito r stress in each charge pump gain state capacitor gain = 1 gain = 1.5 gain = 2 c in v in v in v in c out v in v in 1.5 (max of 5.5 v) v in 2.0 (max of 5.5 v) c1 none v in /2 v in c2 none v in /2 v in if one or both ambient light sensor c omparator inputs (c mp_in and /or d6 ) are used, a small capacitor (0.1 f is recommended) must be connected from the comparator input pins to ground. when a light sensor conversion reading takes place, the voltage on these pins is v als (0.95 v typical, see table 1 ). therefore, the minimum supply voltage for the als sensor should be greater than v als(max) plus the biasing voltage required for the photosensor. any color of led can be used if the v f (forward voltage) is less than 4.1 v. however, using lower v f leds reduces the input power consumption by allowing the charge pump to operate at lower gain states. the equivalent model for a charge pump is shown in figure 50 . 08829-027 v dx c out g v in r out v out i out figure 50 . c harge - pump equivalent circuit model the input voltage is multiplied by the gain (g) and delivered to the output through an effective resistance (r out ). the output current flows through r out and produces an ir drop that yields v out = g v in C i out r out ( g ) (6) the r out term is a combination of the r ds( on ) resistance for the switches used in the charge pump and a small resistance that accounts f or the effective dynamic charge - pump resistance. the r out level changes based on the gain, which is dependent on th e configuration of the switches . typical r out values are given in table 1 and figure 15 to figure 17. v out is also equal to the largest v f of the l eds used plus the voltage drop across the regulating current source. this gives v out = v f (max) + v d x (7) combining equation 6 and equation 7 gives v in = (v f (max) + v d x + i out r out ( g ))/ g (8) this equation is useful for calculating approximate bounds for t he charge pump design. determining the transition point of the charge pump consider the following design example where: v f (max) = 3.7 v i out = 140 ma (7 leds at 20 ma each) r out ( g = 1.5 ) = 3 ? (obtained from figure 12) at the point of a gain transition, v d x = v hr(up) . table 1 gives the typical value of v hr(up) as 0.2 25 v. therefore, the input voltage level when the gain transitions from 1.5 to 2 is v in = (3.7 v + 0.2 25 v + 140 ma 3 ?)/1.5 = 2.90 v layout guide lines use the following layout guidelines: ? for optimal noise immunity, place the c in and c out capacitors as close to their respective pins as possible. these capacitors should share a short ground trace. if the leds are a significant distance from the vout pin, another capacitor on vout, placed closer to the leds, is advisable. ? for optimal efficiency, place the charge - pump fly capacitors as close to the part as possible. ? the ground pin should be connected at the ground for the input and output capacitors. if the lfcsp package is used , the exposed pad must be soldered at the board to the gnd pin. ? unused diode pins[d1:d7] can be connected to ground or vou t, or can remain floating. however, the unused diode current sinks must be disabled by setting them as i ndependent sinks in register 0x05 and then disablin g them in register 0x1b . if th ey are not disabled, the charge - pump efficiency may suffer. ? if the cmp_in phototransistor input is not used, it can be connected to ground or can remain floating.
data sheet ADP8870 rev. b | page 25 of 60 ? if the inte rrupt pin (nint) is not used, connect it to ground or leave it floating. never connect the nint pin to a voltage supply, except through a 1 k series resistor. ? the ADP8870 has an integrated n oise filter on the nrst pin. under normal conditions, it is not necessary to filter the reset line. however, if exposed to an unusually noisy signal, then it is beneficial to add a small rc filter or bypass capacitor on this pin. if the nrst pin is not use d, it must be pulled well above the v ih(max) level (see table 1 ). do not allow the nrst pin to float. example circuit figure 51 shows an example circuit for a generic application. 08829-028 d1 d2 d3 d4 d5 d6 d7 cmp_in v out optional photosensor photo- sensor v dd_als 0.1f 0.1f v in 1f gnd c2+ c2? c2 1f c1+ c1? c1 1f v out 1f ADP8870 n i n t pwm sd a sc l vdd i o n r st figure 51 . generic application schematic
ADP8870 data sheet rev. b | page 26 of 60 i 2 c programming and digital control the ADP8870 provides full software programmability to facilitate its adoption in various product architectures. the i 2 c address is 0101011x (x = 0 during write, x = 1 during read). therefore, the write address is 0x56, and the read address is 0x57. in general, all registers are set to default values on reset or in case of a uvlo event and are read/write unless otherwise specified. unused bits are read as 0. 08829-029 st ack ack ack 0101011 st r/w slave to master master to slave start device id for write operation write = 0 from ADP8870 from ADP8870 from ADP8870 stop select register to write 8-bit value to write in the addressed register b0 b7 b0 b7 b0 b7 register value register address figure 52. i 2 c write sequence 08829-030 slave to master master to slave start device id for write operation from ADP8870 from ADP8870 from ADP8870 stop select register to write 8-bit value to write in the addressed register b0 b7 b0 b7 b0 b7 b0 b7 st r/w ack ack ack ack 0101011 st rs0101011 r/w from master read = 1 device id for read operation repeated start write = 0 register address register value figure 53. i 2 c read sequence table 8. register set definitions address register name description 0x00 mfdvid manufacturer and device id 0x01 mdcr device mode and status 0x02 int_stat interrupts status 0x03 int_en interrupts enable 0x04 cfgr configuration register 0x05 blsel sink enable backlight or independent 0x06 pwmled pwm enable selection 0x07 bloff backlight off timeout 0x08 bldim backlight dim timeout 0x09 blfr backlight fade-in and fade-out rates 0x0a blmx1 backlight, brightness level 1daylight, maximum current 0x0b bldm1 backlight, brightness level 1daylight, dim current 0x0c blmx2 backlight, brightness level 2bright, maximum current 0x0d bldm2 backlight, brightness level 2bright, dim current 0x0e blmx3 backlight, brightness level 3office, maximum current 0x0f bldm3 backlight, brightness level 3office, dim current 0x10 blmx4 backlight, brightness level 4indoor, maximum current 0x11 bldm4 backlight, brightness level 4 indoor, dim current 0x12 blmx5 backlight, brightness level 5dark, maximum current 0x13 bldm5 backlight, brightness level 5dark, dim current 0x14 to 0x19 reserved reserved 0x1a isclaw independent sink current fade law 0x1b iscc independent sink current control 0x1c isct1 independent sink current timer for led[7:5] 0x1d isct2 independent sink current timer for led[4:1]
data sheet ADP8870 rev. b | page 27 of 60 address register name description 0x1e iscf independent sink cu rrent fade register 0x1f isc1 independent sink current led1 0x20 isc2 independent sink current led2 0x21 isc3 independent sink current led3 0x22 isc4 independent sink current led4 0x23 isc5 independent sink current led5 0x24 isc6 independent sink cur rent led6 0x25 isc7 independent sink current led7, brightness level 1 daylight 0x26 isc7_l2 independent sink current led7, brightness level 2 bright 0x27 isc7_l3 independent sink current led7, bright ness level 3 office 0x28 isc7_l4 independent sink cur rent led7, brightness level 4 indoor 0x29 isc7_l5 independent sink current led7, brightness level 5 dark 0x2a to 0x2c reserved reserved 0x2d cmp_ctl als comparator control register 0x2e als1_en main als comparator level enable 0x2f als2_en second als comparator level enable 0x30 als1_stat main als comparator status register 0x31 als2_stat second als comparator status register 0x32 l2 _ trp level 2 comparator reference 0x33 l2 _ hys level 2 hysteresis 0x34 l3 _ trp level 3 comparator reference 0x35 l3 _ hys level 3 hysteresis 0x36 l4 _ trp level 4 comparator reference 0x37 l4 _ hys level 4 hysteresis 0x38 l5 _ trp level 5 comparator reference 0x39 l5 _ hys level 5 hysteresis 0x3a to 0x3f reserved reserved 0x40 ph1levl first phototransistor ambient light level low byte register 0x41 ph1levh first phototransistor ambient light level high byte register 0x42 ph2levl second phototransistor ambient light level low byte register 0x43 ph2levh second phototransistor ambient light level high byte register
ADP8870 data sheet rev. b | page 28 of 60 regi ster summary the reset value for all bits is 0, except for bits at address 0x00 (see table 10 for the unique reset value of address 0x00 ). table 9 . register map addr name bit 7 bit 6 bit 5 b it 4 bit 3 bit 2 bit 1 bit 0 0x00 mfdvid manufacture id device id 0x01 mdcr d7als _ en int_cfg n stby dim_en gdwn_dis sis_en cmp_autoen bl _ en 0x02 int_stat reserved bloff_int short_int tsd_int ovp_int cmp2_int cmp_int 0x03 int_en reserved bloff_ien short_ ien tsd_ien ovp_ien cmp2_ien cmp_ien 0x04 cfgr sel_ab cmp2_sel blv bl_ law fovr 0x05 blse l reserved d7 sel d6 sel d5 sel d4 sel d3 sel d2 sel d1 sel 0x06 pwmled reserved d7enpwm d6enpwm d5enpwm d4enpwm d3enpwm d2enpwm d1enpwm 0x07 bloff reserved offt 0x08 bld im reserved dimt 0x09 blfr bl_fo bl_fi 0x0a blmx1 reserved bl1_mc 0x0b bldm1 reserved bl1_dc 0x0c blmx2 reserved bl2_mc 0x0d bldm2 reserved bl2_dc 0x0e blmx3 reserved bl3_mc 0x0f bldm3 reserved bl3_dc 0x10 blmx4 reserved bl4_mc 0x11 bldm4 reserved bl4_dc 0x12 blmx5 reserved bl5 _mc 0x13 bldm5 reserved bl5 _dc 0x1a isclaw reserved sc_law 0x1b iscc reserved sc7_en sc6_en sc5_en sc4_en sc3_en sc2_en sc1_en 0x1c isct1 scon sc7off sc6off sc5off 0x1d isct2 sc4off sc3off sc2off sc1off 0x1e iscf scfo scfi 0x1f isc1 reserved scd1 0x20 isc2 reserved scd2 0x21 isc3 reserved scd3 0x22 isc4 reserved scd4 0x23 isc5 reserved scd5 0x24 isc6 reserved scd6 0x25 isc7 scr scd7 0x26 isc7_l2 reserved scd7_l2 0x27 isc7_l3 reserved scd7_l3 0x28 isc7_l4 reser ved scd7_l4 0x29 isc7_l5 reserved scd7_l5 0x2d cmp_ctl filt2 force_rd2 filt force_rd 0x2e als1_en reserved l5_en l4_en l3_en l2_en 0x2f als2_en reserved l5_en2 l4_en2 l3_en2 l2_en2 0x30 als1_stat reserved cmp1_l5_out cmp1_l4_out cmp1_l3_out cmp1_l2_ou t 0x31 als2_stat reserved cmp2_l5_out cmp2_l4_out cmp2_l3_out cmp2_l2_out 0x32 l2_trp l2_trp 0x33 l2_hys l2_hys 0x34 l3_trp l3_trp 0x35 l3_hys l3_hys 0x36 l4_trp l4_trp 0x37 l4_hys l4_hys 0x38 l5 _trp l5 _trp 0x39 l5 _hys l5 _hys 0x40 ph1levl ph1lev_ low 0x41 ph1levh reserved ph1lev_high 0x42 ph2levl ph2lev_low 0x43 ph2levh reserved ph2lev_high
data sheet ADP8870 rev. b | page 29 of 60 register details manufacturer and device id (mfdvid)register 0x00 multiple device revisions are tracked by the d evice id field. this is a read-only register. table 10. mfdvid manufacturer and device id bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 manufacture id device id 0 0 1 1 0 0 0 1 mode control register (mdcr)register 0x01 table 11. mdcr bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 d7als_en int_cfg nstby dim_en gdwn_dis sis_en cmp_autoen bl_en table 12. mdcr bit descriptions bit name bit no. description d7als_en 7 1 = ambient light sensing (als) control of independent sink (isc) d7 is enabled. when the ADP8870 is configured as an isc in register 0x05, then register 0x24 to register 0x28 are used to set the outdoor, bright, office, indoor, and dark current levels for d7. cmpauto_en (in register 0x01) and at least one of the level enable bits (in register 0x2d and/or register 0x 2e) must be set high for this feature to operate. 0 = ambient light sensing (als) control of isc d7 is disa bled (d7 responds as a standard backlight led or isc led). int_cfg 6 interrupt configuration. 1 = processor interrupt deasserts for 50 s and reasserts with pending events. 0 = processor interrupt remains asserted if the host tr ies to clear the interrupt while there is a pending event. nstby 5 1 = device is in normal mode. 0 = device is in standby, only i 2 c is enabled. dim_en 4 dim_en is set by the hardware after a dim timeout. the user may also force the backlight into dim mode by asserting this bit. dim mode can only be entered if bl_en is also enabled. 1 = backlight is operating at the dim current level (bl_en must also be asserted). 0 = backlight is not in dim mode. gdwn_dis 3 1 = the charge pump does not switch down in gain until all leds are off. the charge pump switches up in gain as needed. this feature is useful if the ADP8870 charge pump is used to drive an external load. 0 = the charge pump automatically switches up and down in gain. this provides optimal efficiency, but is not suitable for driving external loads (other than those connected to the diode drivers of the ADP8870). sis_en 2 synchronous independent sinks enable. 1 = enables all led current sinks designated as independent sinks. this bit has no effect if any of the scx_en bits in register 0x1b are set. all of the sink current bits must be set to 0. 0 = disables all sinks designated as independent sinks. this bit has no effect if any of the scx_en bits are set in register 0x1b. all of the sink current bits must be cleared. cmp_autoen 1 1 = backlight automatically responds to the comparator output s. at least one of the level enable bits (register 0x32, register 0x34, register 0x36, and/or re gister 0x38) must be set for this to function. blv values in register 0x04 are overridden. 0 = backlight does not autorespond to comparator level changes. the user can manually select backlight operating levels using the blv bits in register 0x04. bl_en 0 1 = backlight is enabled, but only if the device is not in standby mode. 0 = backlight is disabled.
ADP8870 data sheet rev. b | page 30 of 60 interrupt status register ( int_stat ) register 0 x02 table 13. int_stat bit map bit 7 bit 6 bit 5 4 3 2 1 0 reserved bloff_int short_int tsd_int ovp_int cmp2_int cmp_int table 14. int_stat bit descriptions bit name bit no. description 1 reserved [ 7:6] reserved . b loff _int 5 backlight off . 1 = indicates that the controller has completed a backlight fade profile . 0 = the controller has not automatically completed a backlight fade profile . short_int 4 short - circuit error . 1 = a short - circuit or overload con dition on vout or current sinks was detected . 0 = no short - circuit or overload condition detected . tsd_int 3 thermal shutdown . 1 = device temperature is too high and has been shut down . 0 = no overtemperature condition detected . ovp_int 2 overvo ltage interrupt . 1 = charge - pump output voltage has exceeded v ovp . 0 = charge - pump output voltage has not exceeded v ovp . cmp2_int 1 1 = indicates that the second sensor comparator has been triggered . 0 = the second comparator has not been trigge red . cmp_int 0 1 = indicates that the sensor comparator has been triggered . 0 = the comparator has not been triggered . 1 interrupt bits are cleared by writing a 1 to the flag; writing a 0 or reading the flag has no effect. interrupt enable ( int_en ) register 0 x03 table 15. int_en bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bloff_ien short_ien tsd_ien ovp_ien cmp2_ien cmp_ien table 16. int_en bit descriptions bit name bit no. description reserved [ 7:6 ] reserved. bloff _ien 5 automated backlight off indicator . 1 = the automated b acklight off indicator is enabled . 0 = the automated backlight off indicator is disabled. when this bit is set, an interrupt is set anytime a backlight fade - out completes . this occurs after an automated fade - out or after the completion of a backlight di mming profile. this is useful to synchronize the complete turn off for the backlights with other devices in the application. short_ien 4 short - circuit interrupt enabled. when the short_int status bit is set after an error condition, an interrupt is raise d to the host if the short_ien flag is enabled. 1 = the short - circuit interrupt is enabled. 0 = the short - circuit interrupt is disabled (short_int flag is still asserted). tsd_ien 3 thermal shutdown interrupt enabled. when the tsd_int status bit is set after an error condition, an interrupt is raised to the host if the tsd_ien flag is enabled. 1 = the thermal shutdown interrupt is enabled. 0 = the thermal shutdown interrupt is disabled (tsd_int flag is still asserted). ovp_ien 2 overvoltage in terrupt enabled. when the ovp_int status bit is set after an error condition, an interrupt is raised to the host if the ovp_ien flag is enabled. 1 = the overvoltage interrupt is enabled. 0 = the overvoltage interrupt is disabled (ovp_int flag is stil l asserted).
data sheet ADP8870 rev. b | page 31 of 60 bit name bit no. description cmp2_ien 1 when the cmp2_int status bit is set after an enabled comparator trips, an interrupt is raised if the cmp2_ien flag is enabled. 1 = the second phototransistor comparator interrupt is enabled. 0 = the second phototransistor com parator interrupt is disabled (cmp2_int flag is still asserted). cmp_ien 0 when the cmp_int status bit is set after an enabled comparator trips, an interrupt is raised if the cmp_ien flag is enabled. 1 = the comparator interrupt is enabled. 0 = the comparator interrupt is disabled (cmp_int flag is still asserted). backlight register d escriptions configuration register ( cfgr ) register 0x04 table 17. cfgr bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 sel_ab cmp2_sel blv bl_ law fovr table 18. cfgr bit descriptions bit name bit no. description sel_ab 7 1 = selects second phototransistor ( cmp_in2 ) to control the backlight. 0 = selects main phototransistor (cmp_in) to control the backlight. cmp2_sel 6 1 = second phototransistor enabled, current sink on d6 disabled. 0 = current sink on d6 enabled, second phototransistor disabled. blv [ 5:3] brightness level. this field indicates the brightness level at which the device is operating. the sof tware may force the backlight to operate at one of the three brightness lev els. setting cmp_autoen high (r egister 0x01), automatically set s these values and overwrite s any previously written values. 0 00 = level 1 (daylight). 00 1 = level 2 ( bright ). 010 = level 3 (office). 011 = level 4 (indoor). 100 = level 5 (dark). 101 to 111 = disabled (backlight set to 0 ma) . bl_ law [2:1] backlight transfer law. 00 = square law dac, linear time steps. 01 = square law dac, linear time steps. 10 = square law dac, nonlinear time steps (cubic 1 0). 11 = square law dac, nonlinear time steps (cubic 11 ). fovr 0 backlight fade override. 1 = backlight fade override enabled. 0 = backlight fade override disabled.
ADP8870 data sheet rev. b | page 32 of 60 backlight selection (blsel ) register 0x05 table 19 . blse l bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved d7 sel d6sel d5sel d4sel d3sel d2sel d1sel table 20. blsel bit descriptions bit name bit no. description rese rved 7 reserved . d7 sel 6 diode 7 backlight selection . 1 = selects led 7 as an independent sink . 0 = connects led 7 sink to the back light enable, bl_en . d6sel 5 diode 6 backlight selection . 1 = selects led 6 as an independent sink . 0 = connect s led 6 sink to the backlight enable, bl_en . d5sel 4 diode 5 backlight selection . 1 = selects led 5 as an independent sink . 0 = connects led 5 sink to the back light enable, bl_en . d4sel 3 diode 4 backlight selection . 1 = selects led 4 as indepen dent sink . 0 = connects led 4 sink to the back light enable, bl_en . d3sel 2 diode 3 backlight selection . 1 = selects led 3 as independent sink . 0 = connects led 3 sink to the backlight enable, bl_en . d2sel 1 diode 2 backlight selection . 1 = se lects led 2 as independent sink . 0 = connects led 2 sink to the back light enable, bl_en . d1sel 0 diode 1 backlight selection . 1 = selects led 1 as independent sink . 0 = connects led 1 sink to the back light enable, bl_en . pwm enable selection re gister (pwmled) register 0x06 table 21 . pwmled bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved d7enpwm d6enpwm d5enpwm d4enpwm d3enpwm d2enpwm d1enpwm table 22. pwmled bit descriptions bit name bit no. description reserved 7 reserved . d7en pwm 6 diode 7 backlight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d7. 0 = d7 does not respond to the external pwm signal. d6en pwm 5 diode 6 backl ight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d6. 0 = d6 does not respond to the external pwm signal. d5en pwm 4 diode 5 backlight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d5. 0 = d5 does not respond to the external pwm signal. d4en pwm 3 diode 4 backlight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d4. 0 = d4 does not respond to the ex ternal pwm signal. d3en pwm 2 diode 3 backlight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d3. 0 = d3 does not respond to the external pwm signal.
data sheet ADP8870 rev. b | page 33 of 60 bit name bit no. description d2en pwm 1 diode 2 backlight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d2. 0 = d2 does not respond to the external pwm signal. d1en pwm 0 diode 1 backlight sink pwm enable . 1 = enables the externally applied pwm signal to scale the output current of d1. 0 = d1 does not respond to the external pwm signal. backlight off timeout ( bloff ) register 0x07 table 23. bloff bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved offt table 24. bl off bit descriptions bit name bit no. description reserved 7 reserved . offt [6:0] backlight off time out. after the off timeout period, the backl ight turns off. if the dim time out is enabled, the off ti meout starts after the dim time out . 0000 = time out disabled . 0000001 = 1 sec . 0000010 = 2 sec . 1111111 = 127 sec . backlight dim timeout ( bldim ) register 0x08 table 25. bldim bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved dimt table 26. bldim bit descriptions bit name bit no. description reserved 7 reserved . dimt [6:0] backlight dim time out. after the dim timeout period , the backlight is set to the dim current value. the dim timeout starts after the backlight reaches the m aximum current. 0000 = timeout disabled . 0000001 = 1 sec . 0000010 = 2 sec . 0000011 = 3 sec . 1111111 = 127 sec .
ADP8870 data sheet rev. b | page 34 of 60 backlight fade ( blfr ) register 0x09 table 27. blfr bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 bl_fo bl_fi table 28. blfr bit descriptions bit name bit no. description bl_fo [ 7:4] backlight fade - out rate. if the fade - out is disabled (bl_fo = 0000), the backlight changes instantly (within 100 ms). if the fade - out r ate is set, the backlight fades from its current value to the dim or the off value. the times listed for bl_fo are for a full - scale fade - out (30 ma to 0 ma). fades between closer current values reduce the fade time. see the automat ed fade - in and fade - out s ection for more information. 0000 = 0.1 sec (fade - out disabled) . 1 0001 = 0.3 sec . 0010 = 0.6 sec . 0011 = 0.9 sec . 0100 = 1.2 sec . 0101 = 1.5 sec . 0110 = 1.8 sec . 0111 = 2.1 sec . 1000 = 2.4 sec . 1001 = 2.7 sec . 1010 = 3.0 sec . 1011 = 3.5 sec . 1100 = 4.0 sec . 1101 = 4.5 sec . 1110 = 5.0 sec . 1111 = 5.5 sec . bl_fi [3:0] backlight fade - in rate. if the fade -in is disabled (bl_fi = 0000), the backlight changes instantly (within 100 ms). if the fade -in rate is set, the backlight fades from its current value to its maximum value when the backlight is turned on. the times listed for bl_fi are for a full - scale fade -in (0 ma to 30 ma). fades between closer current values reduce the fade time. se e the automated fade - in and fade - out section for more information. 0000 = 0.1 sec (fade - in disabled) . 0001 = 0.3 sec . 0010 = 0.6 sec . 0011 = 0.9 sec . 1111 = 5.5 sec . 1 even with fade - in and fade - out disabled , the bac klight does not instantaneously fade , but instead fades rapidly in about 1 0 0 ms.
data sheet ADP8870 rev. b | page 35 of 60 backlight level 1 (daylight) maximum cur rent register ( blmx1) register 0x0 a table 29. blmx1 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl1_mc table 30. blmx1 bit descriptions bit name bit no. description reserved 7 reserved . bl1_mc [ 6:0] backlight maximum level 1 (daylight) current. the backlight maximum current can be set according to the square law function (see table 31 for a complete list of values). dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 table 31. diode output currents per dac code dac code current (ma) 1 0x00 0.000 0x01 0.002 0x02 0.007 0x03 0.017 0x04 0.030 0x05 0.047 0x06 0.067 0x07 0.091 0x08 0.119 0x09 0.151 0x0a 0.186 0x0b 0.225 0x0c 0.268 0x0d 0.314 0x0e 0.365 0x0f 0.419 0x10 0.476 0x11 0.538 0x12 0.603 0x13 0.671 0x14 0.744 0x15 0.820 0x16 0.900 0x17 0.984 0x18 1.071 0x19 1.163 0x1a 1.257 0x1 b 1.356 0x1c 1.458 0x1d 1.564 0x1e 1.674 0x1f 1.787 0x20 1.905 0x21 2.026 dac code current (ma) 1 0x22 2.150 0x23 2.279 0x24 2.411 0x25 2.546 0x26 2.686 0x27 2.829 0x28 2.976 0x29 3.127 0x2a 3.281 0x2b 3.439 0x2c 3.601 0x2d 3.767 0x2e 3.936 0x2f 4.109 0x30 4.285 0x31 4.466 0x32 4.650 0x33 4.838 0x34 5.029 0x35 5.225 0x36 5.424 0x37 5.627 0x38 5.833 0x39 6.043 0x3a 6.257 0x3b 6.475 0x3c 6.696 0x3d 6.921 0x3e 7.150 0x3f 7.382 0x40 7.619 0x41 7.859 0x42 8.102 0x43 8.350
ADP8870 data sheet rev. b | page 36 of 60 dac code current (ma) 1 0x44 8.601 0x45 8.855 0x46 9.114 0x47 9.376 0x48 9.642 0x49 9.912 0x4a 10.185 0x4b 10.463 0x4c 10.743 0x4d 11.028 0x4e 11.316 0x4f 11.608 0x50 11.904 0x51 12.203 0x52 12.507 0x53 12.814 0x54 13.124 0x55 13.439 0x56 13.757 0x57 14.078 0x58 14.404 0x59 14.733 0x5a 15.066 0x5b 15.403 0x5c 15.743 0x5d 16.087 0x5e 16.435 0x5f 16.787 0x60 17.142 0x61 17.501 0x62 17.863 0x63 18.230 dac code current (ma) 1 0x64 18.600 0x65 18.974 0x66 19.351 0x67 19.733 0x68 20.118 0x69 20.507 0x6a 20.899 0x6b 21.295 0x6c 21.695 0x6d 22.099 0x6e 22.506 0x6f 22.917 0x70 23.332 0x71 23.750 0x72 24.173 0x73 24.599 0x74 25.028 0x75 25.462 0x76 25.899 0x77 26.340 0x78 26.784 0x79 27.232 0x7a 27.684 0x7b 28.140 0x7c 28.599 0x7d 29.063 0x7e 29.529 0x7f 30.000 1 cubic 10 and cubic 11 laws use the same current settings but vary the time step per dac code.
data sheet ADP8870 rev. b | page 37 of 60 backlight level 1 (daylight) dim current register ( bldm1 ) register 0x0b table 32. bldm1 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl1_dc table 33. bldm1 bit descriptions bit name bit no. description reserved 7 reserved. bl1_dc [ 6:0] backlight level 1 (daylight) dim current. the backlight is set to the dim current value after a dim timeout or when the dim_en flag is set by the user (see table 31 for a complete list of value s). dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 backlight level 2 (bright) maximum current register ( blmx2) register 0x0c table 34. blmx2 backlight maximum level 2 current bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl2_mc table 35. blmx2 backlight maximum level 2 current bit descriptions bit name bit no. description reserved 7 reserved. bl2_mc [ 6:0] backlight level 2 (bright) maximum current (see table 31 for a complete list of values) . dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 backlight level 2 (bright) dim current register ( bldm2) register 0x0d table 36. bldm2 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl2_dc table 37. bldm2 bit descriptions bit name bit no. description reserved 7 reserved. bl2_dc [ 6:0] backlight level 2 (bright) dim current. the backlight is set to the dim current value after a dim timeout or when the dim_en flag is set by the user (see table 31 for a complete l ist of values) . dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000
ADP8870 data sheet rev. b | page 38 of 60 backlight level 3 (office) maximum current register (b lmx3) register 0x0e table 38. blmx3 bit ma p bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl3_mc table 39. blmx3 bit descriptions bit name bit no. description reserved 7 reserved. bl3_mc [ 6:0] backlight level 3 (office) maximum current (see table 31 for a complete list of values) . dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 backlight level 3 (office) dim current register ( bldm3) register 0x0f t able 40. bldm3 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl3_dc table 41. bldm3 bit descriptions bit name bit no. description reserved 7 reserved. bl3_dc [ 6:0] backlight level 3 (of fice) dim current. the backlight is set to the dim current value after a dim timeout or when the dim_en flag is set by the user (see table 31 for a complete list of values) . dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30 .000 backlight level 4 (indoor) maximum current register (b lmx4) register 0x10 table 42. blmx4 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl4_mc tabl e 43. blmx4 bit descriptions bit name bit no. description reserved 7 reserved. bl4_mc [ 6:0] backlight level 4 (indoor ) maximum current (see table 31 for a complete list of values ) . dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000
data sheet ADP8870 rev. b | page 39 of 60 backlight level 4 (indoor) dim current register ( bldm 4 ) register 0x11 table 44. bldm4 bit map bit 7 bit 6 bit 5 bit 4 b it 3 bit 2 bit 1 bit 0 reserved bl4_dc table 45. bldm4 bit descriptions bit name bit no. description reserved 7 reserved. bl4_dc [ 6:0] backlight level 4 (indoor) dim current. the backlight is set to the dim current value after a dim timeout or when the dim_en flag is set by the user (see table 31 for a complete list of values) . dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 backligh t level 5 (dark) maximum current register (b lmx5) register 0x12 table 46. blmx5 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl5_mc table 47. blmx5 bit descriptions bit name bit no. desc ription reserved 7 reserved. bl5_mc [ 6:0] backlight level 5 (dark ) maximum current (see table 31 for a complete list of values ) . dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30 .000 backlight level 5 (dark) dim current register ( bldm 5 ) register 0x13 table 48. bldm5 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved bl5_dc table 49. bld m5 bit descriptions bit name bit no. description reserved 7 reserved. bl5_dc [ 6:0] backli ght level 5 (dark) dim current. the backlight is set to the dim current value after a dim timeout or when the dim_en flag is set by the user (see table 31 for a complete list of values) . dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000
ADP8870 data sheet rev. b | page 40 of 60 independent sink reg ister descriptions independent sink current fade law register ( isc la w ) register 0x1 a table 50. isclaw bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved sc_law table 51. isclaw bit descriptions bit name bit no. description reserved [ 7:2] reserved. sc_law [ 1:0] sc fade transfer law . 00 = square law dac, linear time steps . 01 = square law dac, linear time steps . 10 = square law dac, nonlinear time steps (cubic 1 0). 11 = square law dac, nonlinear time steps (cubic 11). independent sink current cont rol ( iscc) register 0x 1b table 52. iscc bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved sc7_en sc6_en sc5_en sc4_en sc3_en sc2_en sc1_en table 53. iscc bit descriptions bit name bit no. de scription reserved 7 reserved . sc7_en 6 this enable acts on the led 7 . 1 = independent sink current led7 is turned on . 0 = independent sink current led7 is turned off. sc6_en 5 this enable acts on the led 6 . 1 = independent sink current led6 i s turned on . 0 = independent sink current led6 is turned off . sc5_en 4 this enable acts on the led 5 . 1 = independent sink current led5 is turned on . 0 = independent sink current led5 is turned off . sc4_en 3 this enable acts on the led 4 . 1 = independent sink current led4 is turned on . 0 = independent sink current led4 is turned off . sc3_en 2 this enable acts on the led 3 . 1 = independent sink current led3 is turned on . 0 = independent sink current led3 is turned off . sc2_en 1 thi s enable acts on the led 2 . 1 = independent sink current led2 is turned on . 0 = independent sink current led2 is turned off . sc1_en 0 this enable acts on the led 1 . 1 = independent sink current led1 is turned on . 0 = independent sink current l ed1 is turned off .
data sheet ADP8870 rev. b | page 41 of 60 independent sink current time (isct1) register 0x1 c table 54 . isct1 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 scon sc7off sc6off sc5off table 55. isct1 bit descriptions bi t name bit no. description 1 , 2 scon [ 7:6] s ink current on time. if the sink current off time is not disabled, then when the independent current sink is enabled ( register 0x1 b ) , it remain s on for the on time selected (per the following times ) and then turn s off. 00 = 0.2 sec . 01 = 0.6 sec . 10 = 0.8sec. 11 = 1.2 sec . sc7off [ 5:4] independent sink current led7 off time. when the sink current off time is disabled, the sink current remains on while enabled. if the sink current off time is set to a ny other value, then the isc turns off for the off time (per the following listed times) and then turns on according to the scon setting. 00 = off time disabled. 01 = 0.6 sec. 10 = 1.2 sec. 11 = 1.8 sec . sc6off [ 3:2] independent sink current l ed6 off time. when the sink current off time is disabled, the sink current remains on while enabled. if the sink current off time is set to any other value, then the isc turns off for the off time (per the following listed times) and then turns on accordin g to the scon setting. 00 = off time disabled . 01 = 0.6 sec . 10 = 1.2 sec . 11 = 1.8 sec . sc5off [ 1:0] independent sink current led5 off time. when the sink current off time is disabled, the sink current remains on while enabled. if the sink cu rrent off time is set to any other value, then the isc turns off for the off time (per the following listed times) and then turns on according to the scon setting. 00 = off time disabled . 01 = 0.6 sec . 10 = 1.2 sec . 11 = 1.8 sec . 1 an ind ependent sink remains on continuously when scx_en = 1 and scx_off = 00 (disabled). 2 to enable multiple independent sinks, set the appropriate scx_en bits. to create equivalent blinking and fading sequences, enable all independent sinks in one write cycle to cause a preprogrammed sequence to start simultaneously.
ADP8870 data sheet rev. b | page 42 of 60 independent sink current time (isct2) register 0x1d table 56 . isct2 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 sc4off sc3off sc2off sc1off table 57. isct2 bit descriptions designation bit description 1 , 2 sc4off [ 7:6] independent sink current led4 off time. when the sink current off time is disabled, the sink current remains on while enabled. if the sink current off time is set to any other value, then the isc turns off for the off time (per the following listed times) and then turns on according to the scon setting. 00 = off time disabled . 01 = 0. 6 sec . 10 = 1.2 sec . 11 = 1.8 sec . sc3off [ 5:4] independent sink current led3 off time. when the sink current off time is disabled, the sink current remains on while enabled. if the sink current off time is set to any other value, then the isc turns off for the off time (per the following listed times) and then turns on according to the scon setting. 00 = off time disabled . 01 = 0. 6 sec . 10 = 1.2 sec . 11 = 1.8 sec . sc2off [ 3:2] independent sink current led2 off time. when the sink current off time is disabled, the sink current remains on while enabled. if the sink current off time is set to any other value, then the isc turns off for the off time (per the following listed times) and then turns on according to the scon setting. 00 = off time disabled . 01 = 0. 6 sec . 10 = 1.2 sec . 11 = 1.8 sec . sc1off [ 1:0] independent sink current led1 off time. when the sink current off time i s disabled, the sink current remains on while enabled. if the sink current off time is set to any other value, then the isc turns off for the off time (per the following listed times) and then turns on according to the scon setting. 00 = off time disabl ed . 01 = 0. 6 sec . 10 = 1.2 sec . 11 = 1.8 sec . 1 an ind epen dent sink remains on continuously when scx_en = 1 and scx_off = 00 (disabled). 2 to enable multiple independent sinks, set the appropriate scx_en bits. to create equivalent blinking and fading sequences, enable all independent sinks in one write cycle. thi s causes a preprogrammed sequence to start simultaneously.
data sheet ADP8870 rev. b | page 43 of 60 independent sink current fade (iscf ) register 0x1e table 58 . iscf bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 scfo scfi table 59. iscf bit descriptions bit name bit no. description scfo [ 7:4] sink current fade - out time. the maximum fade time is from full - scale to 0 ma . therefore, a fade is shorter between maximum and dim or between dim and off. binary code fade - out times are as follows: 0000 = disabled . 0001 = 0.30 sec . 0010 = 0.60 sec . 0011 = 0.90 sec . 0100 = 1.2 sec . 0101 = 1.5 sec . 0110 = 1.8 sec . 0111 = 2.1 sec . 1000 = 2.4 sec . 1001 = 2.7 sec . 1010 = 3.0 sec . 1011 = 3.5 sec . 1100 = 4.0 sec . 1 101 = 4.5 sec . 1110 = 5.0 sec . 1111 = 5.5 sec . scfi 3:0 sink current fade - in time. the maximum fade time is from 0 ma to full scale . binary code fade - out times are as follows: 0000 = disabled . 0001 = 0.30 sec . 0010 = 0.60 sec . 0011 = 0.9 0 sec . 0100 = 1.2 sec . 0101 = 1.5 sec . 0110 = 1.8 sec . 0111 = 2.1 sec . 1000 = 2.4 sec . 1001 = 2.7 sec . 1010 = 3.0 sec . 1011 = 3.5 sec . 1100 = 4.0 sec . 1101 = 4.5 sec . 1110 = 5.0 sec . 1111 = 5.5 sec .
ADP8870 data sheet rev. b | page 44 of 60 sink current regis ter led1 ( isc1) register 0x 1f table 60. isc1 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd1 table 61. isc1 bit descriptions bit name bit no. description reserved 7 reserved scd1 [ 6:0] sink current. use the following dac code schedule (see table 31 for a complete list of values). dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30 .0 00 sink current register led2 ( isc2) register 0x 20 table 62. isc2 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd2 table 63. isc2 bit descriptions bit name bit no. description reserv ed 7 reserved . scd2 [ 6:0] sink current. use the following dac code schedule (see table 31 for a complete list of values). dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 sink current register led3 ( isc3) register 0x21 table 64. isc3 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd3 table 65. isc3 bit descriptions bit name bit no. description reserved 7 reserved . scd3 [ 6:0] sink current. use the following dac code schedule (see table 31 for a complete list of values). dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000
data sheet ADP8870 rev. b | page 45 of 60 sink current register led4 ( isc4) register 0x 22 table 66. isc4 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd4 table 67. isc4 bit d escriptions bit name bit no. description reserved 7 reserved . scd4 [ 6:0] sink current. use the following dac code schedule (see table 31 for a complete list of values). dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 sink current register led5 ( isc5) register 0x 23 table 68. isc5 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd5 table 69. isc5 bit descriptions bit name bit no. description reserved 7 reserved . scd5 [ 6:0] sink current. use the following dac code schedule (see table 31 for a complete list of values). dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 sink current register led6 ( isc6) register 0x 24 table 70. isc6 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd6 table 71. isc6 bit descriptions bit name bit no. description reserved 7 reserved scd6 [ 6:0] sink current. use the following dac code schedule (see table 31 for a complete list of value s). dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000
ADP8870 data sheet rev. b | page 46 of 60 sink current register led7 brightness level 1 ( isc7) register 0x 25 table 72 . isc7 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 scr scd7 table 73. isc7 bit descriptions bit name bit no. description scr 7 1 = sink current 1. 0 = sink current 0. scd7 [ 6:0] for sink current 0, use the following dac code schedule ( see table 31 for a complete list of values). dac code current (ma) 0000000 0.000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 for sink current 1, use the following dac code schedule (see table 74 for a complete list of values). dac code current (ma) 0000000 0.000 0000001 0.004 0000010 0.014 0000011 0.034 1111111 60.000 output currents for led7 with scr = 1 table 74 . diode out put currents for led7 (scr high) dac code diode current (ma) 0x 00 0.000 0x 01 0.004 0x 02 0.014 0x 03 0.034 0x 04 0.06 0x 0 5 0.094 0x 06 0.134 0x 07 0.182 0x 08 0.238 0x 09 0.302 0x 0a 0.372 0x 0b 0.45 0x 0c 0.536 0x 0d 0.628 0x 0e 0.73 0x 0f 0.838 0x10 0.952 0x11 1.076 0x12 1.206 0x13 1.342 0x14 1.488 0x15 1.64 0x16 1.8 dac code diode current (ma) 0x17 1.968 0x18 2.142 0x19 2.326 0x1a 2.514 0x1b 2.712 0x1c 2.916 0x1d 3.128 0x1e 3.348 0x1f 3.574 0x20 3.81 0x21 4.052 0x22 4.3 0x23 4.558 0x24 4.822 0x25 5.092 0x 26 5.372 0x27 5.658 0x28 5.952 0x29 6.254 0x2a 6.562 0x2b 6.878 0x2c 7.202 0x2d 7.534
data sheet ADP8870 rev. b | page 47 of 60 dac code diode current (ma) 0x2e 7.872 0x2f 8.218 0x30 8.57 0x31 8.932 0x32 9.3 0x33 9.676 0x34 10.058 0x35 10.45 0x36 10.848 0x37 11.254 0x38 11.666 0x39 12.086 0x3a 12.514 0x3 b 12.95 0x3c 13.392 0x3d 13.842 0x3e 14.3 0x3f 14.764 0x40 15.238 0x41 15.718 0x42 16.204 0x43 16.7 0x44 17.202 0x45 17.71 0x46 18.228 0x47 18.752 0x48 19.284 0x49 19.824 0x4a 20.37 0x4b 20.926 0x4c 21.486 0x4d 22.056 0x4e 22.632 0x4f 23.216 0x50 23.808 0x51 24.406 0x52 25.014 0x53 25.628 0x54 26.248 0x55 26.878 dac code diode current (ma) 0x56 27.514 0x57 28.156 0x58 28.808 0x59 29.466 0x5a 30.132 0x5b 30.806 0x5c 31.486 0x5d 32.174 0x5e 32.87 0x5f 33.574 0x60 34.284 0x61 35.002 0x62 35.726 0x6 3 36.46 0x64 37.2 0x65 37.948 0x66 38.702 0x67 39.466 0x68 40.236 0x69 41.014 0x6a 41.798 0x6b 42.59 0x6c 43.39 0x6d 44.198 0x6e 45.012 0x6f 45.834 0x70 46.664 0x71 47.5 0x72 48.346 0x73 49.198 0x74 50.056 0x75 50.924 0x76 51.798 0x77 52.68 0x78 53.568 0x79 54.464 0x7a 55.368 0x7b 56.28 0x7c 57.198 0x7d 58.126 0x7e 59.058 0x7f 60.000
ADP8870 data sheet rev. b | page 48 of 60 sink current register led7 brightness level 2 ( isc7_l2) register 0x 26 table 75 . isc7_l2 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd7_l2 table 76. isc7_l2 bit descriptions bit name bit no. description reserved 7 reserved . scd7_l2 [ 6:0] for scr = 0 (register isc7), use the following dac code schedule (see table 31 for a complete list of values) . dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 for scr = 1 (register isc7), use the following dac code schedule (see table 74 for a complete list of values ). dac code current (ma) 0000000 0.000 0000001 0.004 0000010 0.014 0000011 0.034 1111111 6 0 .000 sink current register led7 brightness level 3 ( isc7_l3) register 0x 27 table 77 . isc7_l3 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd7_l3 table 78. isc7_l3 bit descriptions bit name bit no. description reserved 7 reserved . scd7_l3 [ 6:0] for scr = 0 (register isc7), use the following dac code schedule (see table 31 for a complete list of values) . dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 for scr = 1 (register isc7 ), use the following dac code schedule (see table 74 for a complete list of values ). dac code current (ma) 0000000 0.000 0000001 0.004 0000010 0.014 0000011 0.034 1111111 6 0 .000
data sheet ADP8870 rev. b | page 49 of 60 sink current register le d7 brightness level 4 ( isc7_l4) register 0x 28 table 79 . isc7_l4 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd7_l4 table 80. isc7_l4 bit descriptions bit name bit no. description n/a 7 reserved . scd7_l4 6:0 for scr = 0 (register isc7), use the following dac code schedule (see table 31 for a complete list of values) . dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30.000 for scr = 1 (register isc7), use the following dac code schedule (see table 74 for a complete list of values ). dac code current (ma) 0000000 0.00 0000001 0.004 0000010 0.014 0000011 0.034 1111111 6 0 .000 sink current register led7 brightness level 5 ( isc7_l5) register 0x 2 9 table 81 . isc7_l5 bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved scd7_l5 table 82. isc7_l5 bit descriptions bit name bit no. description reserved 7 reserved . scd7_l5 [ 6:0] for scr = 0 (register isc7), use the following dac code schedule (see table 31 for a complete list of values) . dac code current (ma) 0000000 0 .000 0000001 0.002 0000010 0.007 0000011 0.017 1111111 30 for scr = 1 (register isc7), use the following dac code schedule (see table 74 for a complete list of values ). dac code current (ma) 0000000 0.000 0000001 0.004 0000010 0.014 0000011 0.034 1111111 60 .000
ADP8870 data sheet rev. b | page 50 of 60 comparator register descriptions register 0x2d to register 0x39 control the comparators, and register 0x40 to register 0x43 provide the raw data obtained from the comparato rs . als comparator control ( cmp_ctl ) register 0x2 d table 83. cmp_ctl bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 filt2 force_rd2 filt force_rd table 84. cmp_ctl bit descriptions bit name bit no. description filt 2 [ 7:5] filter setting for the second light sensor. 000 = 80 ms . 001 = 160 ms. 010 = 320 ms . 011 = 640 ms . 100 = 1280 ms . 101 = 2560 ms . 110 = 5120 ms . 111 = 10,240 ms . force_rd 2 4 force s a read of the second li ght sensor while the backlight is off . this bit is r eset by the chip a fter the conversion is complete and is ignored if the backlight is enabled. filt [ 3:1] filter setting for the main light sensor. 000 = 80 ms . 001 = 160 ms. 010 = 320 ms . 011 = 640 ms . 100 = 1280 ms . 101 = 2560 ms . 110 = 5120 ms . 111 = 10,240 ms . force_rd 0 force s a read of the main light sensor while the backlight is off . this bit is r eset by the chip a fter the conversion is complete and is ignored if the backlig ht is enabled. main als comparator level enable ( als1_en ) register 0x 2e table 85. als1_en bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved l5_en l4_en l3_en l2_en table 86. als1_en bit des criptions bit name bit no. description reserved [ 7:4] reserved . l5_en 3 1 = the l evel 5 comparator is enabled for the cmp_in comparator. 0 = the level 5 comparator is disabled for the cmp_in comparator. l4_en 2 1 = the level 4 comparator is enabled for the cmp_in comparator. 0 = the level 4 comparator is disabled for the cmp_in comparator. l3_en 1 1 = the level 3 comparator is enabled for the cmp_in comparator. 0 = the level 3 comparator is disabled for the cmp_in comparator. l2_en 0 1 = the level 2 comparator is enabled for the cmp_in comparator. 0 = the level 2 comparator is disabled for the cmp_in comparator.
data sheet ADP8870 rev. b | page 51 of 60 secondary als comparator level enable (als 2 _en) register 0x2 f table 87 . als 2 _en bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved l5_en2 l4_en2 l3_en2 l2_en2 table 88. als2_en bit descriptions bit name bit no. description reserved [ 7:4] reserved . l5_en2 3 1 = the level 5 comparator and auto level changing is enabl ed for the cmp2 comparator. 0 = the level 5 comparator is disabled for the cmp2 comparator. l4_en2 2 1 = the level 4 comparator and auto level changing is enabled for the cmp2 comparator. 0 = the level 4 comparator is disabled for the cmp2 comparato r. l3_en2 1 1 = the level 3 comparator and auto level changing is enabled for the cmp2 comparator. 0 = the level 3 comparator is disabled for the cmp2 comparator. l2_en2 0 1 = the level 2 comparator and auto level changing is enabled for the cmp2 com parator. 0 = the level 2 comparator is disabled for the cmp2 comparator. main als comparator status ( als1_stat ) register 0x30 table 89. als1_stat bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved cmp1_l5_out cmp 1_l4_out cmp1_l3_out cmp1_l2_out table 90. als1_stat bit descriptions bit name bit no. description reserved [ 7:4] reserved . cmp1_l5_out 3 this bit is the output of the level 5 comparator for the main light sensor. cmp1_l4_out 2 t his bit is the output of the level 4 comparator for the main light sensor. cmp1_l3_out 1 t his bit is the output of the level 3 comparator for the main light sensor. cmp1_l2_out 0 t his bit is the output of the level 2 comparator for the main light sen sor. second als comparator status (als2_stat) register 0x31 table 91 . als2_stat bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved cmp2_l5_out cmp2_l4_out cmp2_l3_out cmp2_l2_out table 92. als2_stat bit descriptions bit name bit no. description reserved [ 7:4] reserved . cmp2_l5_out 3 this bit is the output of the level 5 comparator for the second light sensor. cmp2_l4_out 2 this bit is the output of the level 4 comparator for the second l ight sensor. cmp2_l3_out 1 this bit is the output of the level 3 comparator for the second light sensor. cmp2_l2_out 0 this bit is the output of the level 2 comparator for the second light sensor.
ADP8870 data sheet rev. b | page 52 of 60 comparator level 2 threshold (l2_trp ) register 0x 32 table 93 . l2 _ trp bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 l2 _trp table 94. l2_trp bit descriptions bit name bit no. description l2_trp [ 7:0] comparator level 2 threshold. if the comparator input is below l2_trp, then the comparator trips and the backlight enters level 2 (bright) mode. the code settings for photosensor current are as follows : 00000000 = 0 a . 00000001 = 4.3 a . 00000010 = 8.6 a . 00000011 = 12.9 a . 11111010 = 1080 a . 11111111 = 1106 a . although codes above 1111010 (250 d) are possible, they should not be used. furthermore, the maximum value of l2 _ trp + l2 _ hys must not exceed 1111010 (250 d). comparator level 2 hysteresis (l2_hys ) register 0x 33 table 95 . l2 _ hys bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 l2 _ hys table 96. l2_hys bit des criptions bit name bit no. description l2 _ hys [ 7:0] comparator level 2 hysteresis. if the comparator input is above l2_trp + l2_hys, the comparator trips and the backlight enters level 1 (daylight) mode. the code settings for photosensor current hysteresi s are as follows : 0000000 = 0 a . 00000001 = 4.3 a . 00000010 = 8.6 a . 00000011 = 12.9 a . 11111010 = 1080 a . 11111111 = 1106 a . although codes above 1111010 (250 d) are possible, they should not be used. furthermore, the maximum value of l2 _ trp + l2 _ hys must not exceed 1111010 (250 d).
data sheet ADP8870 rev. b | page 53 of 60 comparator level 3 threshold (l3_trp ) register 0x 34 table 97 . l3_trp bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 l3_trp table 98. l3_trp bit descriptions bit name bit no. description l3_trp [ 7:0] comparator level 3 threshold. if the comparator input is below l3_trp, then the comparator trips and the backlight enters level 3 (office) mode. the code settings for photosensor curr ent are as follows : 00000000 = 0 a . 00000001 = 2.16 a . 00000010 = 4.32 a . 00000011 = 8.64 a . 11111111 = 550.8 a . comparator level 3 hysteresis (l 3 _hys ) register 0x 35 table 99. l 3 _hys bit map bit 7 bit 6 bi t 5 bit 4 bit 3 bit 2 bit 1 bit 0 l 3 _hys table 100. l3_hys bit descriptions bit name bit no. description l 3 _hys [ 7:0 ] comparator level 3 hysteresis. if the comparator input is above l 3 _trp + l 3 _hys, the comparator trips and the b acklight enters level 2 ( bright ) mode. the code settings for photosensor current hysteresis are as follows : 00000000 = 0 a . 00000001 = 2.16 a . 00000010 = 4.32 a . 00000011 = 8.64 a . 11111111 = 550.8 a . comparator level 4 threshold (l4_trp ) register 0x 36 table 101 . l4_trp bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 b it 1 bit 0 l4_trp table 102. l4_trp bit descriptions bit name bit no. description l4_trp [ 7:0] comparator level 4 threshold. if the comparator input is below l4_trp, then the comparator trips and the backlight enters level 4 (ind oor) mode. the code settings for photosensor current are as follows : 00000000 = 0 a . 00000001 = 1.08 a . 00000010 = 2.16 a . 00000011 = 4.32 a . 11111111 = 275.4 a .
ADP8870 data sheet rev. b | page 54 of 60 comparator level 4 hysteresis (l4_hys ) register 0x 3 7 table 103 . l4_hys bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 l4_hys table 104. l4_hys bit descriptions bit name bit no. description l4_hys [ 7:0] comparator level 4 hysteresis. if the comparator input is above l4_trp + l4_hys, the comparator trips and the backlight enters level 3 (office) mode. the code settings for photosensor current hysteresis are as follows : 00000000 = 0 a . 00000001 = 1.08 a . 00000010 = 2.16 a . 00000011 = 4.32 a . 11111111 = 275.4 a . comparator level 5 threshold (l5_trp ) register 0x3 8 table 105 . l5_trp bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 b it 1 bit 0 l5_trp table 106. l5_trp bit descriptions bit name bit no. description l5_trp [ 7:0] comparator level 5 threshold. if the comparator input is below l5_trp, then the comparator trips and the backlight enters level 5 (dar k) mode. the code settings for photosensor current are as follows : 0000000 = 0 a . 0000001 = 0.54 a . 0000010 = 1.08 a . 0000011 = 1.62 a . 1111111 = 137.7 a . comparator level 5 hysteresis (l5_hys ) register 0x 39 table 107 . l5_hys bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 l5_hys table 108. l5_hys bit descriptions bit name bit no. description l5_hys [ 7:0] comparator level 5 hysteresis. if the comparator input is above l5_trp + l5_hys, the comparator trips and the backlight enters level 4 (in door) mode. the code settings for photosensor current hysteresis are as follows : 0000000 = 0 a . 0000001 = 0.54 a . 0000010 = 1.08 a . 0000011 = 1.62 a . 1111111 = 137.7 a .
data sheet ADP8870 rev. b | page 55 of 60 first phototransistor register: low byte (ph1levl) register 0x 40 table 109 . ph1levl bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 ph1lev_low table 110. ph1levl bit descriptions bit name bit no. description ph1lev_low [ 7:0] 13- bit conversion value for the first light sensor low byte (bit 7 to bit 0). th e value is updated every 80 ms when the l ight sensor is enabled . this is a read - only register. first phototransistor register: high byte (ph1levh) register 0x 41 table 111. ph1lev h bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved ph1lev_high table 112. ph1levh bit descriptions bit name bit no. description reserved [ 7:5] reserved ph1lev_high [ 4:0] 13- bit conversion value for the first light sensor high byte (bit 12 to bit 8). the value is updated every 80 ms when the light s ensor is enab led . this is a read - only register. the full 13 - bit conversion value is equal (in hex) to raw photosensor conversion (rpc) = ph1lev_high 0x100 + ph1lev_low . t his 13 - bit number has a maximum value of 0x1f40 (decimal = 8000). to convert from th e rpc (decimal) value into the photosensor current, use the following equation: i als (measured) = rpc (decimal)/8000 i als , where i als is given in table 1 . second phototransistor register: low byte (ph2levl) regi ster 0x 42 table 113 . ph2levl bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 ph2lev_low table 114. ph2levl bit descriptions bit name bit no. description ph2lev_low [ 7:0] 13- bit conversion value for the second light sensor low byte (bit 7 to bit 0) . th e value is updated every 80 ms w hen the light sensor is enabled . this is a read - only register. second phototransistor register: high byte (ph2levh ) register 0x 4 3 table 115 . ph2 levh bit map bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 reserved ph2lev_high table 116. ph2levh bit descriptions bit name bit no. description reserved [ 7:5] reserved ph2lev_high [ 4:0] 13- bit conversion value for the second light sensor high byte (bit 12 to bit 8). the v alue is updated every 80 ms w hen the light sensor is enabled . this is a read - only register. the full 13 - bit conversion value is equal (in hex) to raw photosensor conversion (rpc) = ph2lev_high 0x100 + ph2lev _low . this 13 - bit number has a maximum value of 0x1f40 (decimal = 8000). to convert from the rpc (decimal) value into the photosensor current, use the following equation: i als (measured) = rpc(decimal)/8000 i als , where i als is given in table 1 .
ADP8870 data sheet rev. b | page 56 of 60 outline dimensions a b c d e 2.395 2.355 2.315 2.190 2.150 2. 1 10 1 2 3 4 bot t om view (bal l side up) t o p view (bal l side down) bal l a1 identifier 0.40 ref 0.645 0.600 0.555 side view 0.230 0.200 0.170 0.287 0.267 0.247 1.60 ref 1.20 ref coplanarity 0.05 se a ting plane 0.415 0.400 0.385 08-02-2012- a figure 54 . 20 - ball wafer level chip scale package [wl csp ] (cb - 20- 7 ) dimensions shown in millimeters 0 . 5 0 b s c 0 . 5 0 0 . 4 0 0 . 3 0 0 . 3 0 0 . 2 5 0 . 2 0 c o m p l i a n t t o j e d e c s t a n d a r d s m o - 2 2 0 - w g g d . 0 6 1 6 0 9 - b b o t t o m v i e w t o p v i e w e x p o s e d p a d p i n 1 i n d i c a t o r 4 . 1 0 4 . 0 0 s q 3 . 9 0 s e a t i n g p l a n e 0 . 8 0 0 . 7 5 0 . 7 0 0 . 0 5 m a x 0 . 0 2 n o m 0 . 2 0 r e f 0 . 2 5 m i n c o p l a n a r i t y 0 . 0 8 p i n 1 i n d i c a t o r 2 . 6 5 2 . 5 0 s q 2 . 3 5 f o r p r o p e r c o n n e c t i o n o f t h e e x p o s e d p a d , r e f e r t o t h e p i n c o n f i g u r a t i o n a n d f u n c t i o n d e s c r i p t i o n s s e c t i o n o f t h i s d a t a s h e e t . 1 2 0 6 1 0 1 1 1 5 1 6 5 figure 55 . 20 - lead lead frame chip scale package [lfcsp_ w q] 4 mm 4 mm body, very very thin quad (cp - 20 - 10) dimensions shown in millimeters ordering guide model 1 temperature range package description package option ADP8870ac bz - r7 ?40c to +105c 20- ball wl csp , 7 tape and reel cb -20-7 ADP8870acpz - r7 ?40c to +105c 20- lead lfcsp_wq, 7 tape and reel cp -20-10 ADP8870dbcb - evalz ADP8870 daughter card and led board adp887xmb0 - evalz ADP8870 evaluation motherboard 1 z = rohs compliant part.
data sheet ADP8870 rev. b | page 57 of 60 08829-031 figure 56 . tape and reel orientation for wl csp units 08829-032 figure 57 . tape and reel orientation for lfcsp units
ADP8870 data sheet rev. b | page 58 of 60 notes
data sheet ADP8870 rev. b | page 59 of 60 notes
ADP8870 data sheet rev. b | page 60 of 60 notes ? 2012 C 2014 analog devices, inc. all r ights reserved. trademarks and registered trademarks are the property of their respective owners. d08829 - 0 - 1/14(b)

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