AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 1 of 9 www.diodes.com march 2011 ? diodes incorporated new product description the AL3157 is a low noise, constant frequency charge pump dc/dc converter that uses a dual mode load switch (1x), and doubling (2x) conversion for driving white leds. low external part count (one 1f flying capacitor and two 2.2f capacitors at v in and v out ) make this part ideally suited for small, battery-powered applications the AL3157 drives 3 channels at up to 30ma for small screen backlighting and an additional channel up to 210ma for led flash or led flashlight ? all from a 2.7v to 5.5v input. the AL3157 uses two control inputs (en1/2) to enable/disable it and pwm dim the led current. en2 controls/pwm dims the backlight leds at 30ma per channel and en1 controls/pwm dims the flash/flashlight leds at 210ma. each output is equipped with built-in protection for v out short circuit and auto-disable for led failure conditions. built-in soft-start circuitr y prevents excessive in-rush current during start-up and mode switching. a low-current shutdown feature disconnects the load from v in to reduce quiescent current less than 1a. the AL3157 is available in a lead-free, space-saving thermally enhanced 12-pin 3x3mm dfn package. pin assignments v in v out c n d4 c p d1 d2 en1 7 6 5 4 3 2 1 10 11 12 9 8 pgnd en2 exposed pad ( top view ) d3 gnd u-dfn3030-12 features ? dual-mode 1x and 2x charge pump ? up to 300ma drive capability o 3-channel for backlight ? 30ma/ch o 1-channel for flight/light ? 210ma ? v in range: 2.7v to 5.5v ? two simple pwm dimming control inputs up to 50khz ? 1.2 mhz constant switching frequency ? built-in thermal, open-circuit and v out short circuit protection ? soft start for reducing in-rush current ? i q <1a in shutdown ? thermally-enhanced dfn3030-12 package: available in ?green? molding compound (no br, sb) ? lead free finish/ rohs compliant (note 1) applications ? smart touch phone led backlighting ? pda white led backlighting ? backlighting + torch light notes: 1. eu directive 2002/95/ec (rohs). all applicable rohs exemptions applied. please visit our website at http://www.diodes.com/products/lead_free.html typical application circuit AL3157 v out d1 d2 d3 d4 en2 en1 en2 en1 2.2f c in v in v in 1f c 1 c p c n 5 3 6 12 10 8 7 1 11 4 pgnd gnd 29 2.2f c out flash/ light (en1) backlight (en2) AL3157 v out d1 d2 d3 d4 en2 en1 en2 en1 2.2f c in v in v in 1f c 1 c p c n 5 3 6 12 10 8 7 1 11 4 pgnd gnd 29 2.2f c out flash/ light (en1) backlight (en2)
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 2 of 9 www.diodes.com march 2011 ? diodes incorporated new product pin descriptions pin name pin number description en2 1 enable pin 2: controls outputs d2, d3 and d4 pgnd 2 charge pump switch ground: connect to gnd c n 3 negative terminal of flying capacitor v in 4 input power supply. decouple with a 2.2f capacitor between this pin and ground. c p 5 positive terminal of flying capacitor v out 6 charge pump output to drive d1~d4 load circuit. decouple with a 2.2f capacitor between this pin and ground. d4 7 current sink input #4. drive up to 30ma led current. connect to v out when un-used. d3 8 current sink input #3. drive up to 30ma led current. connect to v out when un-used. gnd 9 ground d2 10 current sink input #2. drive up to 30ma led current. connect to v out when un-used. en1 11 enable pin 1: controls output d1 d1 12 current sink input #1. drive up to 210ma led current. connect to v out when un-used. ep ep pad exposed pad (bottom). connect to gnd directly underneath the package. functional block diagram short circuit protection c n c p v in gnd current control charge pump switches v out over voltage protection en1 under voltage lockout bandgap oscillator over temperature protection d1 d2 d3 d4 en2 digital control block
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 3 of 9 www.diodes.com march 2011 ? diodes incorporated new product absolute maximum ratings (note 2) symbol description rating unit esd hbm human body model esd protection 2 kv esd mm machine model esd protection 200 v v in input voltage -0.3 to 6 v v en1,2,3 en1, en2, en3 to gnd voltage -0.3 to v in +0.3 v i out maximum dc output current 300 ma t j operating junction temperature range 125 c t lead maximum soldering temperature (at leads, 10 sec) 300 c notes: 2. exceeding absolute maximum ratings will cause permanent damage to the device. recommended operating conditions symbol parameter min max unit v in input voltage 2.7 5.5 v v enl ( 1, 2 ) en1,2 threshold low 0 0.4 v v enh ( 1,2 ) en1,2, threshold high 1.4 v in v t a operating ambient temperature -40 85 c electrical characteristics v in = 4v, c in = c out = 2.2f, c 1 = 1f; t a = 25c unless otherwise noted. symbol parameter test conditions min typ. max unit i q quiescent current 1x mode, 3.0 v in 5.5, active, no load current 0.3 0.6 ma 2x mode, 3.0 v in 5.5, active, no load current 2 5 i shdn shutdown current en1, en2 = 0 1 a i d2~4 backlight led drive sink current accuracy (note 3) i dx = 30ma 28.5 30 31.5 ma i d1 flash/light led drive sink current accuracy (note 3) i d1 = 210ma 199.5 210 220.5 ma i d-match current matching between any two backlight led drive current sink outputs (note 4) v f : d2:d4 = 4v 1 2 % r out charge pump v out open loop resistance 1x mode 0.5 2x mode 4.5 v th-dx 1x to 2x transition threshold at d2, d3 and d4 pins i d = 30ma 150 mv v th-d1 1x to 2x transition threshold at d1 pin i d1 = 210ma 150 mv v hs mode transition threshold 500 mv t ss soft-start time 100 s f sw switching frequency 1.2 mhz t en1,2 en1,2 off timeout 20 ms uvlo v in under-voltage lockout 1.8 2 2.2 v i en1,2 en1, 2 input leakage -1 1 a t shdn thermal shutdown protection 160 o c t hys thermal shutdown hysteresis 10 o c ja thermal resistance junction-to-ambient u-dfn3030-12 (note 5) 55.29 o c/w notes: 3. determined by the mean of channels 2,3 and 4 currents, eg (i d2 + i d3 + i d4 )/3 4. determined by the maximum sink current (max), the minimum sink current (min), and the average sink current (avg). two matc hing numbers are calculated as (max-avg)/avg and (avg-min)/avg. the largest number of the two (worst case) is as the matching data. 5. device mounted on fr-4 substrate, 2"*2", 2oz, copper, double-sided pc board .
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 4 of 9 www.diodes.com march 2011 ? diodes incorporated new product typical performance characteristics turn-on in 1x mode 100us/div turn-on in 2x mode 100us/div turn-off in 1x mode 200ms/div turn-off in 2x mode 200ms/div load characteristics in 2x mode 500ns/div pwm dimming control (duty cycle=50%) 10us/div vout 2v/div en1,2 2v/div v in =4.2v t a =25c iin 300ma/div vout 2v/div en1,2 2v/div iin 300ma/div v in =3.0v t a =25c vout 2v/div en1,2 2v/div iin 300ma/div v in =3.0v t a =25c iin 300ma/div v in =4.2v t a =25c en1,2 2v/div vout 2v/div v in =3.0v t a =25c vin 100mv ac /div vout 100mv ac /div iin 100ma ac /div iin 300ma/div v in =4v freq=20khz duty cycle=50% t a =25c en 2v/div id1 200ma/div
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 5 of 9 www.diodes.com march 2011 ? diodes incorporated new product typical performance characteristics (continued) v f =3.27v t a =25c v in =4v v in =4v v en(h) v en(l) v in =2.7v v in =4.0v channels 2 to 4 channels 2 to 4 t a =25c
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 6 of 9 www.diodes.com march 2011 ? diodes incorporated new product functional description the AL3157 is a dual-mode high efficiency charge pump (1x and 2x) device, driving 3-channel standard backlight leds and one high-current flash/torch led, intended for white led backlight applications. an internal comparator circuit compares the voltage at each constant current sink input against a reference voltage. to ensure maximum power efficiency, the most appropriate switching mode (1x and 2x) is automatically selected. the apl3157 requires only three external components: one 1f ceramic flying capacitor (c 1 ) for the charge pump, one 2.2f ceramic input capacitor (c in ), and one 2.2f ceramic charge pump output capacitor (c out ). the each output channel of the AL3157 can drive three individual leds with a maximum current of 30ma per channel and a flash/torch led with a maximum current of 210ma. these can be paralleled to give a total output current of 300ma. led control table disabled current sinks unused current channels must be disabled by connecting the sinks to vout with only a small sense current flowing through the disabled channel. soft-start soft-start is incorporated to prevent excessive in-rush current during power-up, mode switching, and transitioning out of stand-by mode. short-circuit protection short-circuit protection function is incorporated to prevent excessive load current when either flying cap terminals or output pin electrically tied to a very lower voltage or ground. over-voltage protection over-voltage protection function is incorporated to limit the output voltage under a safe value to avoid on-chip device breakdown. under-voltage lockout under-voltage lockout feature disables the device when the input voltage drops below uvlo threshold. thermal auto shutdown when the die temperature exceeds the thermal limit, the device will be disabled and enter stand-by mode. the operation resumes whenever the die cools off sufficiently. pwm dimming control the AL3157 provides simple pwm dimming control through enx pins, and the current is adjusted by the duty cycle of the signal applied on enx pin. the recommended pwm frequency is from 200hz to 50khz depending on applications. . en1 en2 d1 d2, d3, d4 0 0 off off 0 1 off on 1 0 on off 1 1 on on
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 7 of 9 www.diodes.com march 2011 ? diodes incorporated new product ordering information AL3157 x - 7 package f : u-dfn3030-12 packing 7 : 7? tape & reel AL3157 x - 7 package f : u-dfn3030-12 packing 7 : 7? tape & reel device package code packaging (note 7) 7? tape and reel quantity part number suffix AL3157f-7 f u-dfn3030-12 3000/tape & reel -7 notes: 7. pad layout as shown on diodes inc. suggested pad layout document ap02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf marking information (1) u-dfn3030-12 y : year : 0~9 w : week : a~z : 1~26 week; ( top view ) x : a~z : green y w x xx xx : b7 : AL3157 z : represents 52 and 53 a~z : 27~52 week; part number package identification code AL3157f u-dfn3030-12 b7 package information (1) package type: u-dfn3030-12 2.3 / 2.5 0.18/0.28 0.45typ 1.5 / 1.7 2.9 / 3.1 0.10 m c a b 0.25/0.55 r 0 . 3 b 0.25 bottom view 2.9 / 3.1 a a 0/0.05 0.57/0.63 0.15max. c 0.25 b 2x- 2x 0.08 c 0.10 c seating plane
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 8 of 9 www.diodes.com march 2011 ? diodes incorporated new product tape orientation (note 8) notes: 8. the taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/a p02007.pdf
AL3157 high efficiency 1x/2x charge pump led driver for small screen backlighting and flashlight AL3157 document number: ds35116 rev. 1 - 2 9 of 9 www.diodes.com march 2011 ? diodes incorporated new product important notice diodes incorporated makes no warranty of any kind, express or implied, with regards to this document, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction). diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or ot her changes without further notice to this document and any product described herein. diodes incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does diodes incorpora ted convey any license under its patent or trademark rights, nor the rights of others. any customer or user of this document or pr oducts described herein in such applications shall assume all risks of such use and will agree to hold diodes incorporated and all the companies whose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthoriz ed sales channel. should customers purchase or use diodes incorporated products for any unintended or unauthorized application, customers shall indemnify and hold diodes incorporated and its representatives harmless against all claims, damages, expenses, and attorney fee s arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. products described herein may be covered by one or more united states, international or foreign patents pending. product names and markings noted herein may also be covered by one or more united states, international or foreign trademarks. life support diodes incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the chief executive officer of diodes incorporated. as used herein: a. life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. b. a critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of diodes incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by diodes incorporated. further, customers must fully indemnify diodes incorporated and its representatives against any damages arising out of the use of diodes incorporated products in such safety-critical, life support devices or systems. copyright ? 2011, diodes incorporated www.diodes.com
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