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dual 750 ma led flash driver with i 2 c-compatible interface data sheet adp1660 rev. 0 document feedback information furnished by analog devices is believed to be accurate and reliable. however, 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 respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 ?2012 analog devices, inc. all rights reserved. technical support www.analog.com features ultracompact solution small, 2 mm 1.7 mm, 12-ball wlcsp package smallest footprint, 1 mm height, 1 h power inductor led current source for local led grounding simplified routing to and from leds improved led thermal dissipation synchronous 3 mhz pwm boost converter, no external diode high efficiency: 90% peak reduces high levels of input battery current during flash limits battery current drain in torch mode i 2 c programmable currents up to 750 ma in flash mode per led with 7% accuracy for currents above 100 ma torch mode programmable dc battery current limit programmable flash timer up to 1600 ms low battery mode to reduce led current automatically device control i 2 c-compatible control registers external strobe and torch input pins transmitter mask (txmask) input safety features thermal overload protection inductor fault detection led short-circuit/open-circuit protection applications camera-enabled cellular phones and smartphones digital still cameras, camcorders, and pdas functional block diagram adp1660 10f 1.0h input voltage = 2.7v to 5.0 v v o u t pgnd sw strobe 10f led1 led2 en sgnd scl sda torch/ txmask gpio up to 750ma up to 750ma v i n 11018-001 figure 1. led2 digital input/ output li-ion+ pgnd c 1 l1 inductor led1 c2 area = 16.4mm 2 11018-002 figure 2. pcb layout general description the adp1660 is a very compact, highly efficient, dual white led flash driver for high resolution camera phones that improves picture and video quality in low light environments. the device integrates a programmable 1.5 mhz or 3.0 mhz synchronous inductive boost converter, an i 2 c-compatible interface, and two 750 ma current sources. the high switching frequency enables the use of a tiny, 1 mm high, low cost, 1 h power inductor, and the parallel current sources permit led cathode grounding for thermally enhanced, low emi, and compact layouts. the led driver maximizes efficiency over the entire battery voltage range to maximize the input-power-to-led-power conversion and minimize battery current draw during flash events. a programmable dc battery current limit safely maximizes led current for all led forward voltage and battery voltage conditions. a txmask input enables fast reduction of the flash led currents and battery current during a power amplifier current burst. the i 2 c-compatible interface can be used to program timers and currents and to read back status bits for operation monitoring and safety control. the adp1660 comes in a compact, 12-ball, 0.5 mm pitch wlcsp package and operates within specification over the full ?40c to +125c junction temperature range.
adp1660 data sheet rev. 0 | page 2 of 28 table of contents features .............................................................................................. 1 applications ....................................................................................... 1 functional block diagram .............................................................. 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications ..................................................................................... 3 recommended specifications: input and output capacitance and inductance ............................................................................. 4 i 2 c- compatible interface timing specifications ..................... 5 absolute maximum ratings ............................................................ 6 thermal data ................................................................................ 6 thermal resistance ...................................................................... 6 esd caution .................................................................................. 6 pin configuration and function descriptions ............................. 7 typical performance characteristics ............................................. 8 theory of operation ...................................................................... 10 white led driver ...................................................................... 10 modes of operation ................................................................... 10 assist light mode ....................................................................... 11 flash mode .................................................................................. 11 assist to flash mode .................................................................. 12 torch mode ................................................................................. 12 torch to flash mode .................................................................. 12 txmask operation ................................................................... 12 independent trigger mode s ...................................................... 13 fixed 5 v output mode ............................................................. 13 frequency foldback ................................................................... 13 low battery led current foldback ........................................ 13 battery input dc current limit .............................................. 14 fixe d 5 v output mode with torch ........................................ 15 safety features ................................................................................. 16 short - circuit fault ..................................................................... 16 overvoltage fault ....................................................................... 16 dynamic overvoltage protection mode ................................. 16 timeout fault .............................................................................. 16 overtemperature fault .............................................................. 16 current limit .............................................................................. 16 input undervoltage .................................................................... 16 soft start ...................................................................................... 16 reset using the enable (en) pin ............................................. 16 clearing faults ............................................................................ 16 i 2 c interface .................................................................................... 17 register map ................................................................................... 18 register details ........................................................................... 18 applications information .............................................................. 24 external component selection ................................................ 24 pcb layout ...................................................................................... 25 outline dimensions ....................................................................... 26 ordering guide .......................................................................... 26 revision history 10/12 revision 0: initial version
data sheet adp1660 rev. 0 | page 3 of 28 specifications v in 1 = 3 . 6 v, t j = ?40c to +125c for minimum/maximum specifications, and t a = 25c for typical specifica tions, unless otherwise noted. table 1. parameter 2 test conditions /comments min typ max unit supply input voltage range 2.7 5.0 v undervolt age lockout threshold v in falling 2.3 2.4 2.5 v undervoltage lockout hysteresis 50 100 150 mv shutdown current, en = 0 v t j = ?40c to +85c, current into vin pin, v in = 2.7 v to 4.5 v 0.2 1 a standby current, en = 1.8 v t j = ?40c to +85c, current into vin pin, v in = 2.7 v to 4.5 v 3 10 a operating quiescent current t orch mode, i led = 100 ma 5.3 ma sw switch leakage current t j = ?40c to +85c, v sw 3 = 5 v 2 a t j = 25c, v sw 3 = 5 v 0.5 a led driver led current assist light, torch mode current assist light value setting = 0 (0 0000 binary) 0 ma assist light value setting = 16 ( 1 00 00 binary) 200 ma flash mode current flash value setting = 0 (00 0000 binary) 0 ma flash value setting = 60 ( 11 1100 binary) 750 ma led current error p er channel i led = 200 ma to 750 ma ? 5 1 + 5 % i led = 100 ma to 187.5 ma ?7 1 +7 % i led = 50 ma to 87.5 ma 3 % i led = 25 ma to 37.5 ma 6 % i led = 12.5 ma 10 % led channel mismatch i led = 275 ma to 750 ma 0.5 3 % i led = 137.5 ma to 262.5 ma 1 4 % i led = 25 ma to 125 m a 2 % i led = 12.5 ma 4 % led current source headroom flash mode , i led = 750 ma 290 mv torch mode , i led = 200 ma 190 mv led1/led2 ramp - up time 0.6 ms led1/led2 ramp - down time 0.1 ms switching regulator switching frequency switchi ng frequency = 3 mhz 2.8 3.0 3.2 mhz switching frequency = 1.5 mhz 1.4 1.5 1.6 mhz minimum duty cycle switching frequency = 3 mhz 14 % switching frequency = 1.5 mhz 7 % n - fet resistance 60 m p - fet resistance 50 m voltage output mode vout voltage 4.575 5 5.425 v output current 500 ma line regulation i load at vout pin = 300 ma 0.3 %/v load regulation ?0.7 %/a pas s - through mode transition flash mode v in to led1/led2, entry i led 1 = i led2 = 750 ma 580 mv v in to led1/led2 , exit i led1 = i led2 = 750 ma 435 mv torch mode v in to led1/led2, entry i led = 200 ma 380 mv v in to led1/led2, exit i led = 200 ma 285 mv
adp1660 data sheet rev. 0 | page 4 of 28 parameter 2 test conditions /comments min typ max unit digital inputs/gpio pin input lo gic low voltage 0.54 v input logic high voltage 1.26 v gpio, strobe pull - down resistance 390 k torch glitch filtering delay 4 from gpio ( torch ) rising edge to device start 7.4 8 .0 8.6 ms safety features maximum timeout f or flash 1600 ms timer accuracy ?7.0 +7.0 % dc current limit 5 dc current value setting = 0 (000 binary) 0.9 1.0 1.1 a dc current value setting = 1 (001 binary) 1.1 1.25 1.4 a dc current value setting = 2 (010 binary) 1.35 1.5 1.65 a dc current value setting = 3 (011 binary) 1.55 1.75 1.95 a dc current value setting = 4 (100 binary) 1.8 2.0 2.2 a dc current v alue setting = 5 (101 binary) 2.0 2.25 2.5 a dc current value setting = 6 (110 binary) 2.25 2.5 2.75 a dc current value setting = 7 (111 binary) 2.45 2.75 3.1 a low battery mode transition voltage error 3.2 % hysteresis 50 mv coil peak c urrent limit 6 peak current value setting = 0 (00 binary) 2.02 2.25 2.5 a peak current value setting = 1 (01 binary) 2.47 2.75 3.0 a peak current value setting = 2 (10 binary) 2.9 3.25 3.5 a peak current value setting = 3 (11 binary) 3.15 3.5 3.85 a overvoltage detection threshold 5.15 5.5 5.9 v led1/led2 short - circuit detection comparator reference voltage 1.0 1. 3 v thermal shutdown threshold t j rising 150 c t j falling 140 c 1 v in is the input voltage to the circuit. 2 all limits at temperature extremes are guaranteed via correlation using standard statistical quality control (sqc). 3 v sw is the voltage on the sw switch pin. 4 guaranteed by design. torch glitch filtering depends directly on internal oscillator tolerances . 5 all dc current limit values are guaranteed by design except for the 1.25 a setting, which is tested in production. 6 all coil peak current limit values are guaranteed by design except for the 2.25 a setting, which is tested in production. recommended specific ations: input and ou tput capacit ance and inductance table 2. parameter symbol test conditions /comments min typ max unit capacitance c min t a = ?40c to +125c input 4.0 10 f output 3.0 10 20 f minimum and maximum inductance l t a = ?40c to +125c 0.6 1.0 1.5 h
data sheet adp1660 rev. 0 | page 5 of 28 i 2 c-compatible interface timing specifications table 3. parameter 1 min max unit description f scl 1000 khz scl clock frequency t high 0.26 s scl high time t low 0.5 s scl low time t su, dat 50 ns data setup time t hd, dat 0 0.9 s data hold time t su, sta 0.26 s setup time for repeated start t hd, sta 0.26 s hold time for start/repeated start t buf 0.5 s bus free time between a stop and a start condition t su, sto 0.26 s setup time for stop condition t r 20 + 0.1 c b 2 120 ns rise time of scl and sda t f 20 + 0.1 c b 2 120 ns fall time of scl and sda t sp 0 50 ns pulse width of suppressed spike c b 2 400 pf capacitive load for each bus line 1 guaranteed by design. 2 c b is the total capacitance of one bus line in picofarads. timing diagram sd a 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 11018-003 figure 3. i 2 c-compatible interf ace timing diagram
adp1660 data sheet rev. 0 | page 6 of 28 absolute maximum rat ings table 4. parameter rating vin, sda, scl, en, gpio, strobe, led1, led2, sw, vout to p gnd ?0.3 v to +6 v pgnd to sgnd ?0.3 v to +0.3 v ambient temperature range (t a ) ?40c to +85c junction temperature range (t j ) ?40c to +125c storage temperature jedec j - std -020 esd human body model 1 000 v charged device model 500 v machine model 150 v stresses above those listed under absolute maximum ratings may 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 se ction of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. thermal data the adp1660 may be damaged if the junction temperatur e ( t j ) limits are exceeded. monitoring ambient temperature ( t a ) does not guarantee that t j is within the specified temperature limits. in applications with high power dissipation and poor pcb thermal resistance, the maximum t a may need to be derated. in applications with moderate power dissipation and low pcb thermal resistance, the maximum t a can exceed the maximum limit as long as t j is within the speci fication limits. the junction temperature (t j ) of the device is dependent on the ambient temperature (t a ), the power dissipation (p d ) of the device , and the junction - to - ambient thermal resistance ( ja ) of the package. maximum t j is calculated from t a and p d using the following formula: t j = t a + (p d ja ) thermal resistance the j unction - to - ambient therm al resistance ( ja ) of the package is based on modeling and calculation using a 4 - layer board. ja is highly dependent on the application and board layout. in applications where high maximum power dissipation exists, close attention to thermal board design is required. the value of ja may vary, depending on pcb material, layout, and environmental conditions. the specified value of ja is based on a 4 - layer, 4 in ch 3 in ch , 2 ? oz copper board, per jedec standards. for more information, see the an - 617 application note , wafer level chip scale package . in table 5 , ja is specified for a device mounted on a jedec 2s2p pcb. table 5 . thermal resistance package type ja unit 12 - ball wlcsp 75 c/w esd caution
data sheet adp1660 rev. 0 | page 7 of 28 pin configuration an d function descripti ons top view (ball side down) not to scale pgnd sgnd vin sw gpio en vout strobe sda led1 led2 scl 1 a b c d 2 3 bal l a1 indic a t or 1 1018-004 figure 4 . pin configuration table 6 . pin function descriptions pin no. mnemonic description a1 pgnd p ower ground. a2 sgnd signal ground. a3 vin input voltage for the device. connect an input bypass capacitor very close to this pin. b1 sw boost switch. connect the power inductor between sw and the input capacitor. b2 gpio this pin enables the part to f unction in torch mode or functions as a txmask input, depending on the value set using bits[5:4] in register 0x02 (see table 14 ). when this pin is configured as a txmask input, the flash current is reduced to the t xmask current programmed in register 0x07 (for led1) and register 0x0a (for led2) . b3 en enable. set en low to bring the quiescent current (i q ) to <1 a. registers are set to their default value s when en is brought from low to high. c1 vout boost output. connect an output bypass capacitor very close to this pin. this pin is the output for the 5 v external voltage mode. c2 strobe strobe signal input. this pin synchronizes the flash pulse to the image capture. in most cases, this signal comes directly from the image sensor. c3 sda i 2 c data signal . d1 led1 current source for led1. connect this pin to the anode of flash led1. d2 led2 current source for led2. connect this pin to the anode of flash led2. d3 scl i 2 c clock signal.
adp1660 data sheet rev. 0 | page 8 of 28 typical performance charac teristics i led = led current, v led = led output voltage, i bat = battery current. ch1 5.00v ch2 1.00 a ch4 2.00v ch3 500m a m800s 3 4 2 1 t 200s v led1 i led1 strobe inductor current 1 1018-005 figure 5 . startup , flash mode, v in = 3.6 v, i led1 = i led2 = 750 ma ch1 5.00v ch2 100m a ch4 2.00v ch3 100m a m8.00ms 3 4 2 1 t 2.00ms v led1 i led1 i led2 gpio (torch) 1 1018-006 figure 6 . startup , torch mode, v in = 3.6 v, i led1 = i led2 = 150 ma ch1 5.00v ch2 1.00 a ch4 5.00v ch3 500m a m400s 3 4 2 1 t 100s v led1 i led1 strobe inductor current 1 1018-007 figure 7 . torch current to 750 ma flash transition , i led1 = i led2 = 50 ma ch1 2.00v ch2 100m a ch3 50.0m a m800s 3 2 1 t 100s i led1 sw inductor current 1 1018-008 figure 8 . switching waveforms, flash mode, i led1 = i led2 = 750 ma ch1 1.00v ch2 200m a ch4 100m a ch3 1.00v m20.0s 1 3 2 4 t 0.00000s v led1 v in 1 1018-009 i led1 inductor current a ch2 196ma figure 9 . pa ss- through to boost mode transition, single led, i led 1 = 5 0 ma ch1 5.00v ch2 1.00 a ch4 500mv ch3 200m a m20s 3 4 2 1 t 10s v led1 i led1 i bat gpio (txmask) 1 1018-010 figure 10 . entry into txmask mode , i led1 = i led2 = 750 ma to 250 ma
data sheet adp1660 rev. 0 | page 9 of 28 0 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 efficienc y (%) output current (a) v in = 2.7v v in = 3.0v v in = 3.6v v in = 4.2v 1 1018-100 figure 11 . efficiency vs. output current , fixed 5 v output mode ?3 ?2 ?1 0 1 2 3 ?40 ?20 0 20 40 60 80 100 120 led current error (%) temper a ture (oc) 100m a per channe l 200m a per channe l 500m a per channe l 750m a per channe l 1 1018-102 figure 12 . led current error vs. temperature 0 10 20 30 40 50 60 70 80 90 100 100 300 500 700 900 1 100 1300 1500 efficienc y (%) output current (ma) v in = 3.6v v in = 2.7v 1 1018-104 figure 13 . efficiency (p led /p in ) vs. led output current 0 1 2 3 4 5 6 ?40 ?20 0 20 40 60 80 100 120 st andb y current (a) temper a ture (oc) v in = 4.5v v in = 2.7v 1 1018-101 figure 14 . standby current vs. temperature ?0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 ?40 ?20 0 20 40 60 80 100 120 led m a tching (%) temper a ture (oc) 100m a per channe l 200m a per channe l 500m a per channe l 750m a per channe l 1 1018-103 figure 15 . led matching vs. temperature
adp1660 data sheet rev. 0 | page 10 of 28 theory of operation the adp1660 is a high power, i 2 c programmable , dual white led driver ideal for driving white leds for use as a camera flash. the adp1660 includes a boost converter and two current regulator s suitable for powering two high power white led s. white led driver the adp1660 drives a synchronous 3 mhz boost con verter as required to power the high power led s. ? if the sum of the led forward voltage plus the current source headroom voltage is higher than the battery voltage, the boost converter is turn ed on. ? if the battery voltage is higher than the sum of the led forward voltage plus 2 the current source headroom voltage , the boost converter is disabled and the part operates in pass - through mode. the adp1660 uses an integrated p - fet high - side current regulator f or acc urate brightness control. the adp1660 supports the setting of different currents for each led, although this configuration is not recommended. any mis - match in the forward voltage of the two leds translates di rectly to lower efficiency, as well as lower accuracy of the current for the lower voltage led. it is recommended that the voltages on the two leds be kept within 1 v of one another during operation. the user can disable one led and use the other led only, if desired. modes of operation when the enable pin is high, the i 2 c- compatible interface can be used to set the adp1660 to one of seven modes of operation . these modes are configured using the led_mod bits (b its[2:0]) in register 0x0 1 (see table 7 ) . table 7 . modes of operation set by the led_mod bits led_mod bits operating mode 000 s tandby mode , consuming 3 a typical (default ) 001 fixed 5 v o utput mode 010 assist light mode with continuous led current 011 flash mode with led currents up to 750 ma available for up to 1.6 sec 100 independent trigger mode with timeout enabled (led outputs are disabled if they are on longer than the timer value configured by the fl_tim bits ) 101 independent trigger mode with timeout disabled (fl_tim value is ignored) 11 0 fixed 5 v output mode with torch mode (total output current must be below 500 ma) 111 reserved pwm controller p g n d p g n d vout s w p g n d s g n d vin u v l o o v p fault register ic thermal sensing hp led short hp led driver current sense current sense s c l s t r o b e p g n d p g n d a g n d c out 10 f l1 1f input vo lt age = 2.7v to 5.0v c in 10 f gpio s da torch en 5.5v current sense hp led driver high power led current control led2 up to 750ma p g n d up to 750ma interface and control torch txmask io_cfg 2.4v 1 1018-0 1 1 led1 figure 16 . det ailed block diagram
data sheet adp1660 rev. 0 | page 11 of 28 assist light mode a ssist light mode provides continuous led current that is programmable from 0 ma to 200 ma. set the assist light current using the i_tor1 bits in register 0x08 (for led1) and the i_tor2 bits in register 0x0b (for le d2) . to enable assist light mode , set the led_mod bits to 010 in register 0x0 1 , and set the led1_en and/or led2_en bits to 1 in register 0x0f . to d isable assist light mode , set the led_mod bits to 000 ( standby mode ) , or set the led1_en and led2_en bits t o 0. led2 current reg 0x08, i_tor1 = x xxxxma reg 0x0b, i_tor2 = x xxxxma reg 0x01, led_mod = 010 reg 0x0f, led1_en = 1 led2_en = 1 i 2 c data bus reg 0x0f, led1_en = 0 0a i_tor2 led1 current 0a i_tor1 reg 0x0f, led2_en = 0 1 1018-012 figure 17 . enabling assist light mode flash mode flash mode provides up to 750 ma per led for a program - mable time of up to 1.6 seconds. set the flash current using the i_fl1 bits in register 0x06 (for led1) and the i_fl2 b its in register 0x09 (for led2 ) . set the maximum flash duration using the fl_tim bits (bits[3:0]) in register 0x0 2 . to enable flash mode, set the led_mod bits to 011 in register 0x01, and s et the led1_en and/or led2_en bits to 1 in register 0x0f. if the led1_en or led2_en bit is set to 0 , the corresponding led will not output current during the flash, regardless of the flash current level setting. to e nable flash mode without using the strobe pin, set the str_mod bit to 0 in register 0x0 1 (software str obe mode ). when the str_mod bit is set to 1 ( hardware strobe mode ) , setting the strobe pin high enables flash and synchronizes it to the image sensor. hardwa re strobe mode has two timeout modes : level sensitive and edge sensitive. level - sensitive st robe mode in level - sensitive mode, the duration of strobe high sets the duration of the flash up to the maximum time set by the fl_tim timeout bits in register 0x02 (see figure 18 ). if strobe is kept high longer th an the duration set by the fl_tim bits, a timeout fault disables the flash. the timeout fault flag (bit 4) is set in the fault information register (register 0x0c). led2 current reg 0x0f, led1_en = 1 led2_en = 1 reg 0x01, str_mod = 1 str_lv = 1 led_mod = 011 i 2 c data bus 0a i_fl2 strobe reg 0x02, fl_tim = xxxxms reg 0x06, i_fl1 = xx xxxxma reg 0x09, i_fl2 = xx xxxxma adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. adp1660 sets led_mod to 000. led1 current 0a i_fl1 11018-013 figure 18 . flash operation: level - sensitive mode edge - sensitive strobe mode in edge - sensitive mode, a rising edge on the strobe pin enables the flash, and the fl_tim bits set the flash duration (see figure 19) . led2 current reg 0x0f, led1_en = 1 led2_en = 1 0a i_fl2 strobe reg 0x02, fl_tim = xxxxms reg 0x06, i_fl1 = xx xxxxma reg 0x09, i_fl2 = xx xxxxma led1 current 0a i_fl1 fl_tim i 2 c data bus adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. adp1660 sets led_mod to 000. 1 1018-014 reg 0x01, str_mod = 1 str_lv = 0 led_mod = 011 figure 19 . flash operation: edge - sensiti ve mode
adp1660 data sheet rev. 0 | page 12 of 28 assist to flash mode the str_pol bit in register 0x01 can be used to change the default polarity of the strobe pin from active high to active low . additional image sensor - specific assist to flash enable modes are included in the device . i nformati on about these modes is avail - able on request from the analog devices, inc., sales team. led2 current 0a strobe i_tor2 reg 0x0f, led1_en = 1 led2_en = 1 reg 0x01, str_lv = 1 led_mod = 010 i_fl1 led1 current 0a i_tor1 i_fl2 reg 0x02, fl_tim = xxxxms reg 0x06, i _fl1 = xx xxxxma reg 0x08, i_tor1 = x xxxxma reg 0x09, i_fl2 = xx xxxxma reg 0x0b, i_tor2 = x xxxxma i 2 c data bus adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. adp1660 sets led_mod to 000. 1 1018-015 figure 20 . enabling assist to flash (level - sensitive) mode torch mode set the assist/torch light current using the i_tor x bits. to enable to rch mode, set the led_mod bits to 000 ( standby mode ) , and set the led1_en and led2_en bits to 1 in register 0x0f ; then bring gpio high. disable the led current by bringing gpio low or by setting the led1_en and led2_en bits to 0. bringing gpio low during t orch mode automatically sets led1_en and led2_en = 0. to re enable torch mode, set led1_en and led2_en = 1 and bring gpio high again. led2 current 0a i 2 c data bus gpio (torch) i_tor2 led1 current 0a i_tor1 reg 0x08, i_tor1 = x xxxxma reg 0x0b, i_tor2 = x xxxxma reg 0x0f, led1_en = 1 led_mod = 000 led2_en = 1 adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. 1 1018-016 figure 21 . enabling external torch mode using the gpio pin torch to flash mode the driver can mo ve directly from external torch mode (using the gpio pin ) to flash mode by bringing the strobe pin high before gpio is brought low. bringing the gpio (torch) pin low before strobe goes high prevents the flash from firing. the adp1660 returns to standby mode after a successful flash and sets the led1_en and led2_en bits to 0 in register 0x0f. led2 current 0a strobe gpio (torch) i_tor2 reg 0x0f, led1_en = 1 led2_en = 1 reg 0x01, str_lv = 1 led_mod = 000 i_fl1 led1 current 0a i_tor1 i_fl2 reg 0x02, io_cfg = 01 fl_tim = xxxxms reg 0x06, i _fl1 = xx xxxxma reg 0x08, i_tor1 = x xxxxma reg 0x09, i_fl2 = xx xxxxma reg 0x0b, i_tor2 = x xxxxma i 2 c data bus adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. 1 1018-017 figure 22 . enabling flash mode from external torch mode t x mask operation when the adp1660 is in flash mode, the txmask function can reduce the battery load in response to the system enabling a power amplifier. the device remains in flash mode, but the led driver output current is r educe d to the program med txmask current level in less than 21 s. the txmask current level is programmed in register 0x07 (for led1) and in register 0x0a (for led2). gpio (txmask) f l _ t x = 1 led2 current 0a strobe i_tx2 reg 0x0f, led1_en = 1 led2_en = 1 reg 0x01, str_lv = 1 led_mod = 011 i_fl1 led1 current i_tx1 0a i_fl2 reg 0x02, io_cfg = 10 fl_tim = xxxxms reg 0x06, i _fl1 = xx xxxxma reg 0x08, i_tor1 = x xxxxma reg 0x09, i_fl2 = xx xxxxma reg 0x0b, i_tor2 = x xxxxma i 2 c data bus adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. adp1660 sets led_mod to 000. 1 1018-018 figure 23 . txmask operation during flash (level - sensitive) mode after a txmask event occurs, a flag is set in the fault informa - tion register (register 0x0c , bit 3) . when the txmask signal goes low again, the led current reverts to the full flash level in a controlled manner to avoid overshoots on the battery current.
data sheet adp1660 rev. 0 | page 13 of 28 independent trigger mode s when the led_mod bits are set to 100 or 101, the adp1660 allow s for independent triggering of each led at a current level between the configured flash currents and txmask currents. in independent trigger mode, the strobe pin controls led1, and the gpio pin controls led2 (see figure 24 ) . ? when the strobe or gpio pin goes high, the current produced at the led1 or led2 pin i s at the level specified by the i_fl1 bits ( register 0x 06) o r the i_fl2 bits (register 0x09), respectively. ? when the strobe or gpio pin goes low, the current produced at the led1 or led2 pin i s at the level specified by the i_tx1 bits (register 0x07) or the i_tx2 bits (register 0x0a), respectively. led1 current i_tx1 i_fl1 strobe led2 current i_tx2 i_fl2 gpio 1 1018-019 figure 24 . independent t rigger m ode when the led_mod bits are set to 100 , the flash timer is used . if both leds are on for a combined time that is equal to the value specified by the fl_tim bits (both outputs ored), the adp1660 sets both led_enx bits to 0 and sets led_mod to 000. the independent trigger modes (led_mod bits set to 100 or 101) present a possible overtemperature risk ; careful evaluation of their implementation must be performed. befor e enabling either independent trigger mode, contact your local analog devices field applications engineer for assistance. fixed 5 v output mode when the led_mod bits are set to 001, the adp1660 allows v out to be regulated to 5 v. in this mode, the t otal output current must be kept below 500 ma. enabling one or both led s allows low levels of current to the leds. in fixed 5 v output mode, the vout pin is connected to the sw node when the adp1660 is not enabled. do not connect vout directly to a positive external voltage source; doing so causes current to flow from vout to the battery . changing the mode to standby (led_mod = 000) ends voltage regulation ; vout returns t o a value that is approximately the same as vin. frequency foldback the optional f requency foldback feature optimizes efficiency by reducing the switching frequency to 1.5 mhz when the value of v in is slightly less than the value of v out . to e nable freq uency foldback , set the freq_fb bit to 1 in register 0x0 3 . low battery led curr ent foldback as the battery discharges, the lower battery voltage results in higher peak currents through the battery esr, which may cause early shutdown of other devices on the battery . the adp1660 includes an optional low battery detection feature , w hich reduces the flash current to a value from 0 ma to 750 ma when the battery voltage falls below a programmable level. the low batte r y current level can be set from 0 ma to 750 ma using the i_vb_lo bits (bits[5:0]) in register 0x05. to enable low battery detection and to specify the voltage at which this detection becomes active, set the v_vb_lo bits (bits[2:0]) in register 0x04 (see table 8 ). table 8. v dd level for low battery detection v_vb_lo bit value v dd level for low battery detection (v) 000 low battery detection d isabled (default) 001 3.3 010 3.35 011 3.4 100 3.45 101 3.5 110 3.55 111 3.6 if a low battery fault is detected within a programmed window of detection, the lower current is latched for the remainder of the flash. the window size is specified by the v_batt_window bits (bits[4:3]) in register 0x04 (see table 9 ). table 9. low battery detection window size v_batt_window bit value window size (ms) 00 window d isabled ; low battery detection is enabled for the entire flash period 01 1 10 2 11 5 (default) by reducing the window size to the beginning of the flash only , the user can reduce the chance of partial exposure of the picture in the case th at th e image sensor is using a rolling scan. if a global scan is used , it is recommended tha t the low battery detection window be disabled, thereby providing low voltage protection throughout the flash time.
adp1660 data sheet rev. 0 | page 14 of 28 battery input dc current limit the adp1660 has an optional programmable input dc current limit that limits the maximum battery current used over all con- ditions. this feature allows higher led currents to be used in a system with significant variation in led forward voltage (v f ) and supply battery voltage without the risk of exceeding the current allocated to the flash. to enable the input dc current limit, set the il_dc_en bit (bit 0) in register 0x03. to set the input dc current limit, use the il_dc bits (bits[3:1]) in register 0x03 (see table 10). table 10. input dc current limit il_dc bit value dc current limit (a) 000 1.0 001 1.25 010 1.5 011 1.75 100 2.0 (default) 101 2.25 110 2.5 111 2.75 during startup of the flash, if the battery current does not exceed the dc current limit, the led1 and led2 currents are set to the values of the i_fl1 and i_fl2 bits in register 0x06 and register 0x09, respectively. if the battery current exceeds the programmed dc current limit on startup, the led current does not increase further. the dc current limit flag is set in the fault information register (bit 0 of register 0x0c). the fl_i_fl1 bits in register 0x0d and the fl_i_fl2 bits in register 0x0e are set to the actual led current values and are available for readback. reg 0x02, fl_tim = xxxxms reg 0x06, i_fl1 = xx xxxxma reg 0x09, i_fl2 = xx xxxxma reg 0x03, il_dc_en = 1 il_dc = xx a i 2 c data bus strobe programmed led current actual led current adp1660 sets fl_idc (reg 0x0c) to 1. adp1660 sets fl_i_fl1 (reg 0x0d) to actual led current. adp1660 sets led1_en to 0. adp1660 sets led2_en to 0. adp1660 sets led_mod to 000. reg 0x0f, led1_en = 1 led2_en = 1 reg 0x01, str_lv = 1 led_mod = 011 adp1660 sets fl_i_fl2 (reg 0x0e) to actual led current. 11018-020 figure 25. dc current limit operation in a low battery, high led v f case the camera system shown in figure 26 can adjust the image sensor settings based on the known reduced led current for a low battery and a high v f led. select flash current select max battery current preflash strobe dc limit exceeded? led current = programmed led current no led current locked at current value yes battery current = programmed dc limit read led current (reg 0x0d and reg 0x0e) adjust image sensor strobe strobe 11018-021 figure 26. use of the dc current limit in an optimized camera system
data sheet adp1660 rev. 0 | page 15 of 28 fixed 5 v output mode with tor ch the adp1660 can be used as a 5 v boost converter for a key - pad led driver voltage or a n audio voltage rail (see figure 27 and figure 28) . in this mode, the device supplies up to 500 ma with torch currents available on the led outputs. to enable 5 v outp ut voltage mode with torch currents , 1. set the led1_en and led2_en bits in register 0x0f to 0. 2. e nable the 5 v output by set ting the led_mod bits (bits [ 2 :0] in register 0x01) to 110. 3. enable the led outputs by setting the led1_en and led2_en bits to 1. 4. if des ired, set the torch/assist currents for the leds using register 0x08 (for led1) and register 0x0b (for led2 ) . these currents can be toggled with the gpio (torch) pin. if the led is enabled and the gpio (torch) pin is low, the led output s low levels of cur rent. the vout pin is connected to the sw node when the adp1660 is not enabled. do not connect vout directly to a positive external voltage source ; doing so cause s current to flow from vout to the battery. adp1660 10f 1.0h input voltage = 2.7v to 5.0v pgnd sw strobe 10f led1 en sgnd scl sda gpio off on i 2 c bus sda, scl en applications processor 3.2 megapixel to 5.0 megapixel cmos image sensor power-on reset vout = 5.0v keypad led driver vdd gnd vout* vin led2 *the vout pin is connected to the sw node when the adp1660 is not enabled. vout should not be connected directly to a positive external voltage source because this will cause current to flow from vout to the battery. 1 1018-022 figure 27 . adp1660 voltage regulation mode: keypad led driver applicatio n vout = 5.0v 8.5%, i max = 500ma shutdown vdd out+ out? in+ gnd sd audio in? audio in+ ssm2315 80k? 80k? 160k? 160k? bias 0.1f adp1660 10f 1.0h input voltage = 2.7v to 5.0v pgnd sw strobe 10f en sgnd scl sda gpio off on i 2 c bus sda, scl en applications processor 3.2 megapixel to 5.0 megapixel cmos image sensor power-on reset vout* vin in? 47nf 47nf fet driver pop/click suppression internal oscillator modulator (-) led1 led2 1 1018-023 *the vout pin is connected to the sw node when the adp1660 is not enabled. vout should not be connected directly to a positive external voltage source because this will cause current to flow from vout to the battery. figure 28 . adp1660 voltage regu lation mode: class - d audio application
adp1660 data sheet rev. 0 | page 16 of 28 safety features for critical fault conditions such as output overvoltage, flash timeout, led output short circuit, and overtemperature condi - tions the adp1660 has built - in protection modes. if a critical fault occurs, the led1_en and led2_en bits in register 0x0f are set to 0 and the driver shuts down. the appropriate fault bit is set in the fault information register (register 0x0c). the pro - cessor can read the fault in formation register through the i 2 c interface to determine the nature of the fault condition. when the fault register is read, the fault bit is cleared. if a noncritical event occurs, the le d driver continues to oper - ate. noncritical events include txmask event , dc current limit reached, or soft inductor current limit reached . the corresponding information bits are set in the fault information register (register 0x0c) until the processor reads them. short - circuit fault when the fla sh driver is disabled, the high - side current regu - lator disconnects the dc path between the battery and the led, protecting the system from an led short circuit. the led1 and l ed2 pin s feature short - circuit protection that monitors the led voltage when the led driver is enabled. if the voltage on the led1 or led2 pin remains below the short - circuit detection threshold, a short circuit is detected, and bit 6 of the fault information register (register 0x0c) is set high. t he adp1660 remai ns disabled until the processor clears the fault register. overvoltage fault the adp1660 contains a comparator at the vout pin that monitors the voltage between vout and p gnd. if the voltage exceeds 5.5 v (typ ical), the adp1660 shuts down. bit 7 in the fault information register (register 0x0c) is read back as high. the adp1660 is disabled until the fault is cleared, e nsuring prot ection against an open circuit , which would cause an overvoltage condition . dynamic overvoltage protection mode dynamic overvoltage protection ( ovp ) mode is a programmable feature that prevents the vout voltage from exceeding the ovp level whil e maintaining as much current as possible through the led s. dynamic ovp mode prevents an overvoltage fault in the case of a much higher than expected led forward voltage. if the led forward voltage is reduce d due to a rise in led tempera - ture, the adp1660 transitions out of dynamic ovp mode and regulates the led at the programmed current level. to enable dynamic ovp mode, s et bit 6 of register 0x0 3 high. timeout fault if hardware strobe mode is enabled and stro be is set to level - sensitive mode (register 0x0 1 , bits[5: 4 ] = 1 1 ) and if the strobe pin remains high for longer than the programmed timeout period, the timeout fault bit (register 0x0c, bit 4) is read back as high. the adp1660 remains disabled until the proce ssor clears the fault register. the timeout value is set using the fl_tim bits (bits[3:0]) in register 0x02. overtemperature faul t if the junction temperature of the adp1660 rises above 150c, a thermal protection circuit shuts down the device. bit 5 of the fault information register (register 0x0c) is set high. the adp1660 remains disabled until the proce ssor clear s the fault register. current limit an internal switch limits battery current by ensuring that the peak inductor current does not exceed the limit programmed using bit s[7:6] in register 0x0 1 . by default , the soft inductor peak current limit mode is disable d (register 0x03, bit 7 = 1). when the soft inductor peak current limit is disabled and the peak inductor current exceeds the limit, bit 1 of the fault infor - mation register (register 0x0c) is set high. the adp 1660 shuts down and remains disabled until the processor clears the fault register. when the soft inductor peak current limit is enabled (register 0x03, bit 7 = 0) and the peak inductor current reaches the limit, bit 1 of the fault information register (r egister 0x0c) is set high . t he inductor and led current cannot increase further, but the adp1660 continues to operate. input undervoltage the adp1660 includes a b attery undervoltage lockout circuit. during fixed 5 v output or led operation, if the battery voltage falls below the input uvlo threshold (2.4 v typical) , the adp1660 shuts down. a power - on reset circuit rese ts the registers to their default values when the voltage rises above the uvlo rising threshold. soft start the adp1660 uses a soft start that controls the rate of increase of battery current at startup by dig itally controlling the output current ramp. the maximum soft start time is 0.6 ms. reset using the enab le (en) pin a low - to - high transition on the en pin resets all registers to their default values. bringing en low reduces the i q to 0.2 a (typical). clea ring faults the bits in the fault information register ( register 0x0c ) are clear ed automatically when the processor reads the fault register ( provided that the fault s no longer exist) .
data sheet adp1660 rev. 0 | page 17 of 28 i 2 c interface the ad p1660 includes an i 2 c - compatible serial interface for control of the led current s , as well as for readback of system status registers. the i 2 c chip address is 0x30 (0x60 in write mode and 0x61 in read mode). additional i 2 c addresses are available on reque st. figure 29 shows the i 2 c write sequence for a single register. the subaddress byte selects the register that is written to. the adp1660 sends an acknowledgment to the master after the 8 - bit data byte is written. figure 30 shows the i 2 c read sequence for a single register. for information about the registers and descriptions of all register bits, see the register map section. subaddress chip address 0 1 1 0 0 0 0 0 0 0 0 = write 0 adp1660 ack adp1660 ack adp1660 ack adp1660 receives data s t s p master stop 1 1018-024 figure 29 . i 2 c write sequence for a single register adp1660 ack adp1660 ack adp1660 ack chip address 0 1 1 0 0 0 0 0 0 1 0 master stop ch i p addr es s s t s t 0 1 1 0 0 0 0 0 1 0 0 = write 1 = read s p master ack a dp1660 se nd s da t a subaddress 1 1018-025 figure 30 . i 2 c read sequence for a single register
adp1660 data sheet rev. 0 | page 18 of 28 register map the highest bit number (7) represents t he most significant bit; the lowest bit number (0) represents the least significant bit. table 11 . register map address register name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 0x00 design information device_id rev_id 0x01 ou tput mode il_peak str_lv str_mod str_pol led_mod 0x02 gpio and timer led_sd test _sr io_cfg fl_tim 0x03 additional features cl_soft dyn_ovp sw_lo freq_fb il_dc il_dc_en 0x04 l ow battery mode enable reserved v_batt_window v_vb_lo 0x05 low battery mode cu rrent reserved i_vb_lo 0x06 led1 flash current reserved i_fl1 0x07 led1 txmask current reserved i_tx1 0x08 led1 torch/assist current reserved i_tor1 0x09 led2 flash current reserved i_fl2 0x0a led2 txmask current reserved i_tx2 0x0b led2 torch/assist current reserved i_tor2 0x0c fault information fl_ovp fl_sc fl_ot fl_to fl_tx fl_vb_lo fl_il f l _idc 0x0d led1 flash current fault readback reserved fl_i_fl1 0x0e led2 flash current fault readback reserved fl_i_fl2 0x0f led enable mode reserved led2_en led1_en register details table 12 . design information register (register 0x00) bits bit name access description [7:3] device_id r device id for the adp1660 (00011). [2:0] rev_id r revision id. table 13 . output mode register (register 0x01) bits bit name access description [7:6] il_peak r/w these bits set the inductor peak current limit. 00 = 2.25 a. 01 = 2.75 a. 10 = 3.25 a (default). 11 = 3.5 a. 5 str_lv r/w this bit set s the sensitivity for the strobe pin. 0 = edge sensitive. 1 = level sensitive (default). 4 str_mod r/w this bit sets the strobe mode. 0 = software strobe mode; software flash occurs when the output is enabled in flash mode. 1 = hardware s trobe mode; the strobe pin must go high for flash (default). 3 str_pol r/w this bit sets the polarity of the strobe pin. 0 = active low. 1 = active high (default). [2:0] led_mod r/w these bits set the led output mode . 000 = standby mode (default). 001 = fixed 5 v output mode . 010 = assist light mode. 011 = flash mode. 100 = independent trigger mode with timeout enabled. 101 = independent trigger mode with timeout dis abled. 110 = fixed 5 v output mode with torch mode (total output current must be below 500 ma). 111 = reserved.
data sheet adp1660 rev. 0 | page 19 of 28 table 14. gpio and timer register (register 0x02) bits bit name access description 7 led_sd r/w th is bit configures the shutdown function for led1 and led2. 0 = enter shutdown after led1 or led2 flash or tor ch ends (default). 1 = do not enter shutdown after led1 or led2 flash or torch ends. 6 test _sr r/w test mode only . t his bit must be set to its default value, 1 . do not set this bit to 0. [5:4] io_cfg r/w these bits configure the gpio pin. 00 = high imped ance (default). 01 = torch mode. 10 = txmask operation mode. 11 = torch mode without the 8 ms deglitch filter. [3:0] fl_tim r/w these bits set the flash timer value . 0000 = 100 ms. 0001 = 200 ms. 0100 = 500 ms. 0110 = 700 ms. 1001 = 1000 ms. 1100 = 1300 ms. 1111 = 1600 ms (default). table 15 . additional features register ( register 0x03) bits bit name access description 7 cl_soft r/w this bit enables or disables the soft inductor peak current limit. 0 = enable soft induc tor peak current limit. 1 = disable soft inductor peak current limit (default) . t he adp1660 is disabled when the inductor peak current limit is reached. 6 dyn_ovp r/w this bit enables or disables dynamic ovp. 0 = disable dynamic ovp (default). 1 = enable dynamic ovp. 5 sw_lo r/w this bit sets the switching frequency. 0 = 3 mhz (default). 1 = 1.5 mhz. 4 freq_fb r/w this bit enables or disables frequency foldback to 1.5 mhz . 0 = disable frequency foldback (def ault). 1 = enable frequency foldback. [3:1] il_dc r/w these bits set the input dc current limit . (bit 0 must be set to 1.) 000 = 1.0 a . 001 = 1.25 a . 010 = 1.5 a . 011 = 1.75 a . 100 = 2.0 a (default) . 101 = 2.25 a . 110 = 2.5 a . 111 = 2.75 a . 0 il_dc_en r/ w this bit enables or disables the input dc current limit function. 0 = disable input dc current limit (default). 1 = enable input dc current limit.
adp1660 data sheet rev. 0 | page 20 of 28 table 16 . low battery mode enable register (register 0x04) bits bit name access description [7:5] reserved r/w reserved. [4:3] v_bat t_ w indow r/w these bits set the window size for low battery detection mode . 00 = window disabled; low battery detection is enabled for the entire flash period. 01 = window enabled for 1 ms. 10 = window enabled for 2 ms. 11 = window enabled for 5 ms (default). [2:0] v_vb _lo r/w these bits enable or disable low battery detection and set the battery voltage level at which the low battery detection function is enabled. 000 = low battery detection disabled ( default). 001 = low battery detection enabled at 3.3 v. 010 = low battery detection enabled at 3.35 v. 011 = low battery detection enabled at 3.4 v. 100 = low battery detection enabled at 3.45 v. 101 = low battery detection enabled at 3.5 v. 110 = low batt ery detection enabled at 3.55 v. 111 = low battery detection enabled at 3.6 v. table 17 . low battery mode current register (register 0x05) bits bit name access description [7:6] reserved r/w reserved. [5:0] i_vb_lo r/w these bit s set the flash current value for the low battery voltage setting . the current setting is equal to the value of these six bits multiplied by 12.5 ma (i_vb_lo 12.5). the maximum current value is 750 ma. 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma. 10 1000 = 500 ma (default). 11 1100 = 750 ma. 11 1111 = 750 ma. table 18 . led1 flash current register (register 0x06) bits bit name access description [7:6] reserved r/w reserved. [5:0] i_fl1 r/w th ese bits set the flash current value for led1. the current setting is equal to the value of these six bits multiplied by 12.5 ma (i_fl1 12.5). the maximum current value is 750 ma. 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma. 10 1000 = 500 ma (default). 11 1100 = 750 ma. 11 1111 = 750 ma.
data sheet adp1660 rev. 0 | page 21 of 28 table 19 . led1 txmask current register (register 0x07) bits bit name access description [7:6] reserved r/w reserved. [5:0] i_tx1 r/w these bits set the txmas k current value for led1. the current setting is equal to the value of these six bits multiplied by 12.5 ma (i_tx1 12.5). the maximum txmask current value is 750 ma. 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma (default). 1 0 1000 = 500 ma. 11 1100 = 750 ma. 11 1111 = 750 ma. table 20 . led1 torch/assist current register (register 0x08) bits bit name access description [7:5] reserved r/w reserved. [4:0] i_tor1 r/w these bits set the torch/assist current value for led1. the current setting is equal to the value of these five bits multiplied by 12.5 ma (i_tor1 12.5). the maximum current value is 200 ma. 0 0000 = 0 ma. 0 0100 = 50 ma (default). 0 1000 = 100 ma. 0 1100 = 150 ma. 1 0000 = 20 0 ma. 1 1111 = 200 ma. table 21 . led2 flash current register (register 0x09) bits bit name access description [7:6] reserved r/w reserved. [5:0] i_fl2 r/w these bits set the flash current value for led2. the current setting is equal to the value of these six bits multiplied by 12.5 ma (i_fl2 12.5). the maximum current value is 750 ma. 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma. 10 1000 = 500 ma (default). 11 1100 = 750 ma. 11 1111 = 750 ma .
adp1660 data sheet rev. 0 | page 22 of 28 table 22 . led2 txmask current register (register 0x0a) bits bit name access description [7:6] reserved r/w reserved. [5:0] i_tx2 r/w these bits set the txmask current value for led2. the current setting is equal to the value of these six bits multiplied by 12.5 ma (i_tx2 12.5). the maximum txmask current value is 750 ma. 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma (default) . 10 1000 = 500 ma . 11 1100 = 750 ma. 11 1111 = 750 ma. table 23 . led2 torch/assist current register (register 0x0b) bits bit name access description [7:5] reserved r/w reserved. [4:0] i_tor2 r/w these bits set the torch/assist current value for led2. the current setting is equal to the value o f these five bits multiplied by 12.5 ma (i_tor2 12.5). the maximum current value is 200 ma. 0 0000 = 0 ma. 0 0100 = 50 ma (default). 0 1000 = 100 ma. 0 1100 = 150 ma. 1 0000 = 200 ma. 1 1111 = 200 ma. table 24 . fault i nformation register (register 0x0c) bits bit name access description 7 fl_ovp r 0 = no overvoltage fault (default). 1 = overvoltage fault. 6 fl_sc r 0 = no short - circuit fault (default). 1 = short - circuit fault. 5 fl_ot r 0 = no overtemperature fault (d efault). 1 = overtemperature fault. 4 fl_to r 0 = no timeout fault (default). 1 = timeout fault. 3 fl_tx r 0 = no txmask operation mode during last flash (default). 1 = txmask operation mode occurred during last flash. 2 fl_vb_lo r l ow battery detection threshold status; low battery detection must be enabled in register 0x0 4. 0 = v dd is greater than the configured low battery threshold (default) . 1 = v dd is less than the configured low battery threshold . 1 fl_il r 0 = no inductor peak current limit faul t (default). 1 = inductor peak current limit fault. 0 fl_idc r dc current limit threshold status; dc current limit must be enabled in register 0x03. 0 = dc current limit not reached (default). 1 = dc current limit reached.
data sheet adp1660 rev. 0 | page 2 3 of 28 table 25 . led1 flash current fault readback register (register 0x0d) bits bit name access description [7:6] reserved r reserved. [5:0] fl_i_fl1 r these bits contain the flash current value for led1 when the dc current limit fault occurs. the current setting is equal to the value of these six bits multiplied by 12.5 ma (fl_i_fl1 12.5). 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma. 10 1000 = 500 ma. 11 1100 = 750 ma. table 26 . led2 flash current fault r eadback register (register 0x0e) bits bit name access description [7:6] reserved r reserved. [5:0] fl_i_fl2 r these bits contain the flash current value for led2 when the dc current limit fault occurs. the current setting is equal to the value of these s ix bits multiplied by 12.5 ma (fl_i_fl2 12.5). 00 0000 = 0 ma. 00 0001 = 12.5 ma. 00 1000 = 100 ma. 01 0100 = 250 ma. 10 1000 = 500 ma. 11 1100 = 750 ma. table 27. led enable mode register (register 0x0f) bits bit name a ccess description [7:2] reserved r/w reserved. 1 led2_en r/w this bit enables or disables the led2 output. 0 = disable led2 output (default). 1 = enable led2 output. to enable both channels at once, set both led 2 _en and led1 _en to 0 and then set both bit s to 1 in the same i 2 c write command. if led1 is already enabled and the user tries to set the led2_en bit to 1, this write is ignored. 0 led1_en r/w this bit enables or disables the led1 output. 0 = disable led1 output (default). 1 = enable led1 output. to enable both channels at once, set both led1_en and led2_en to 0 and then set both bits to 1 in the same i 2 c write command. if led 2 is already enabled and the user tries to set the led 1 _en bit to 1, this write is ignored.
adp1660 data sheet rev. 0 | page 24 of 28 applications informa tion e xternal component se lection selecting the inductor the adp1660 boost converter increases the battery voltage to allow driving of two led s when the forward voltage of the leds is higher than the battery voltage minus 2 the current source headroom voltage. this allows the converter to regulate the led current over the entire battery voltage range and with a wide variation of led forward voltage s. the inductor saturation current should be greater than the sum of the dc input current and half the inductor ripple current. a reduction in the effective inductance due to saturation increases the inductor ripple current. table 28 provides a list of suggested inductors. table 28 . suggested inductors vendor value (h) part no. dcr (m?) i sat (a) dimensions l w h (mm) toko 1.0 fdsd0312 43 4.5 3.0 3.0 1.2 toko 1.0 dfe2520 50 3.4 2.5 2.0 1. 0 coilcraft 1.0 xfl3010 43 2.4 3.0 3.0 1.0 murata 1.0 lqm32p_g0 48 3 3.2 2.5 1.0 fdk 1.0 mip 3226d 40 3 3. 2 2. 6 1. 0 selecting the input capacitor the adp1660 requires an input bypass capacitor to supply tran - sient currents while maintaining constant input and output voltages. the input capacitor carries the input ripple cu rrent, allowing the input power source to supply only the dc current. increased input capacitance reduces the amplitude of the switching frequency ripple on the battery. due to the dc bias characteristics of ceramic capacitors, the recommended capacitor is a 10.0 f, 6.3 v, x5r/x7r ceramic capacitor. higher input capacitor value s help to reduce the input voltage ripple and improve transient response. to minimize supply noise, place the input capacitor as close to the vin pin of the adp1660 as possible. a low esr capacitor is required. table 29 provides a list of suggested input and output capacitors. table 29 . suggested input and output capacitors vendor value part no. dimensions l w h (mm) murata 10 f, 6.3 v grm188r60j106me47 1.6 0.8 0.8 tdk 10 f, 6.3 v c1608jb0j106k 1.6 0.8 0.8 taiyo yuden 10 f, 6.3 v jmk107bj106ma 1.6 0.8 0.8 selecting the output capacitor the output capa citor maintains the output voltage and supplies the led curre nt during the on period of the n - fet power switch . it also stabilizes the loop. the recommended capacitor is a 10.0 f , 6.3 v, x5r/x7r ceramic capacitor (see tabl e 29). note that dc bias characterization data is available from capa c itor manufacturers and should be taken into account when selecting input and output capacitors. c apacitors of 6.3 v or 10 v are best for most designs. higher output capacitor values reduce the output voltage ripple and improve load transient response. when selecting an output capacitor value, it is also important to account for the loss of capacitance due to output voltage dc bias. ceramic capacitors have a variety of dielectri cs, each with different behavior over temperature and applied voltage. capacitors must have a dielectric that ensures the minimum capacitance over the necessary temperature range and dc bias conditions. x5r or x7r dielectrics with a voltage rating of 6.3 v or 10 v are recommended for best performance. y5v and z5u dielectrics are not recom - mended for use with any dc - to - dc converter because of their poor temperature and dc bias characteristics. the worst - case capacitance accounting for capacitor variation ove r temperature, component tolerance, and voltage is calculated using the following equation: c eff = c out (1 ? tempco ) (1 ? tol ) where: c eff is the effective capacitance at the operating voltage. tempco is the worst - case capacitor temperature coefficient . tol is the worst - case component tolerance. for example, a 10 f , x5r capacitor has the following characteristics : tempco from ?40c to +85c is 15%. tol is 10%. c out at v out (max) = 5 v is 3 f (see figure 31). 10 0 ?10 ?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 6.30 5.04 3.78 2.52 dc bias vo lt age (v) ca p aci t ance change (%) 1.26 0 1 1018-026 figure 31 . dc bias characteristic of a 10 f , 6.3 v ceramic capacitor substituting these values in the equation yields c eff = 3 f (1 ? 0.15) (1 ? 0.1) = 2 .3 f the effective capacitance needed for stability, which includes te mperature and dc bias effects, is 3.0 f.
data sheet adp1660 rev. 0 | page 25 of 28 pcb layout poor layout can affect performance, causing electromagnetic interference (emi) and electromagnetic compatibility (emc) problems, ground bounce, and power losses. poor layout can also affect regulation and stability. figure 32 shows an optimized layout implemented using the following guidelines: ? place the inductor, input capacitor, and output capacitor close to the ic using short tracks. these components carry h igh switching frequencies and large currents. ? use as wide a trace as possible between t he inductor and the sw pin. the easiest path for this trace is through the center of the output capacitor. ? route the led1/led2 path away from the inductor and sw node to minimize noise and magnetic interference. ? maximize the size of ground metal on the component side of the board to help with thermal dissipation. ? use a ground plane with two or three vias connecting to the component side ground near the output ca pacitor to reduce noise interfe rence on sensitive circuit nodes. analog devices applications engineers can be contacted through the analog devices sales team to discuss different layouts based on system design constraints. led2 digital input/ output pgnd c1 l1 led1 area = 16.4mm 2 1 1018-027 li-ion+ i nduc t o r c 2 figure 32 . layou t of the adp1660 driving a high power white led
adp1660 data sheet rev. 0 | page 26 of 28 outline dimensions a b c d 0.660 0.600 0.540 1.695 1.655 1.615 2.060 2.020 1.980 1 2 3 bot t om view (bal l side up) t op view (bal l side down) end view 0.360 0.320 0.280 1.50 ref 1.00 ref 0.50 ref bal l a1 identifier 09-07-2012- a sea ting plane 0.270 0.240 0.210 coplanarity 0.05 figure 33 . 12 - ball wafer level chip scale package [wlcsp] (cb - 12- 7 ) dimensions shown in millimeters ordering guide model 1 temperature range package description package option 2 branding adp1660acbz - r7 ? 40 c to +125 c 12- ball wafer level chip scale package [wlcsp] cb -12-7 lm7 adp1660cb - evalz evaluation board 1 z = rohs compliant part. 2 this package option is halide free.
data sheet adp1660 rev. 0 | page 27 of 28 notes
adp1660 data sheet rev. 0 | page 28 of 28 notes i 2 c refers to a communications protocol originally developed by philips semiconductors (n ow nxp semiconductors). ? 2012 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d11018 - 0- 10/12(0)

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