Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver

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Abel Ball
5 years ago
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1 Feaures and Benefis Proprieary adapive conrol scheme (1, 1.5, 2 ) 0.5% ypical LED curren maching 2 separae serial inerfaces for dimming conrol Drives up o 6 whie LEDs (4 display backligh, 2 flash/orch) 30 ma per LED channel for display backligh 100 ma per LED channel for flash/orch backligh 320 ma oal oupu curren capabiliy Low EMI design and sof-sar funcion Shor circui, overvolage, hermal shudown proecion 0.75 mm very hin profile, 3 mm 3 mm package Package: 16 pin QFN/MLP (suffix ES) Descripion The high efficiency charge pump ICs offer a simple, low-cos whie LED driver soluion for driving four display backligh and wo flash/orch/video mode whie LEDs. Using a proprieary conrol scheme (1, 1.5, and 2 ), he can deliver well-mached LED curren while mainaining he highes efficiency and low EMI. The LED curren is regulaed over he enire range of Li+ baery volage o provide uniform inensiy. LED brighness and on/off can be conrolled for 4 display backligh LEDs and 2 flash/orch LEDs hrough 2 single-wire serial inerface pins. The is available in a very hin profile (0.75 mm nominal heigh) 3 mm 3 mm QFN/MLP 16 pin package. Applicaions include: Whie LED backlighs for cellular phones, PDAs Digial cameras, camcorders Oher porable device whie LED backlighing 320 ma WLED flash/orch Approximae Scale 1:1 Typical Applicaions RSET VBATT 2.7 o 5.5 V On/Off and Conrol VIN VOUT + LED1 + ENM LED5 ENF LED6 D1 D2 D3 D4 D5 D6 D1-D4 Backligh; D5-D6 Flash COUT RSET VBATT 2.7 o 5.5 V On/Off and Conrol VIN VOUT + LED1 + ENM LED5 ENF LED6 D1 D5 D6 D1-D4 Backligh; D5-D6 Flash COUT Figure ma backligh wih ma flash Figure ma flash RSET VBATT 2.7 o 5.5 V On/Off and Conrol VIN VOUT + LED1 + ENM LED5 ENF LED6 D1 COUT 1 μf RSET VBATT On/Off and Conrol VIN VOUT + LED1 D1 D2 + D3 ENM D4 D5 LED5 D6 ENF LED6 D1-D4 Main; D5-D6 Flash V IN >V f (max)+0.2 V, V f = LED forward drop Figure ma flash Figure 4. High efficiency curren sink 8530-DS, Rev. 1

2 Funcional Block Diagram + + VIN Fracional Charge Pump (1, 1.5, and 2 ) VOUT + COUT ENM ENF Conrol, Clock, and Reference Minimum Selec LED1 Curren Mirror I REF I REF LED5 LED6 + RSET Ab so lue Max i mum Ra ings Inpu or Oupu Volage VIN, VOUT, +,, +, o o 6 V All oher pins o V IN V VOUT Shor Circui o...coninuous Operaing Ambien Temperaure, T A C o 85 C Juncion Temperaure, T J(max) C Sorage Temperaure, T S C o 150 C Package Thermal Characerisics R θja = 47 C/W, on a 4-layer board based on JEDEC spec Addiional informaion is available on he Allegro Web sie. Device package is lead (Pb) free, wih 100% mae in leadframe plaing. Use he following complee par number when ordering: Par Number Packaging* Package Type EESTR-T 7-in. reel, 1500 pieces/reel ES, 3 3 mm MLP-16 *Conac Allegro for addiional packing opions. 2

3 Pin-ou Diagram ES Package VIN VOUT 2 3 EP LED1 ENF 4 9 ENM LED6 LED (Top View) Terminal Lis Table Name Number Funcion 13 Negaive erminal of capacior. Connec capacior beween + and Posiive erminal of capacior. 15 Negaive erminal of capacior + 1 Posiive erminal of capacior. Connec capacior beween + and. ENF 4 Enable and dimming conrol inpu for flash/orch. ENM 5 Enable and dimming conrol inpu for display backligh. EP Exposed meal pad on boom side. Connec his o ground plane for beer hermal performance. 12 Ground. 3 Connec RSET resisor o ground o se desired consan curren hrough backligh LEDs. I LED(max) = 220 x 0.6 V / R SET LED1,,, and 8, 9, 10, and 11 Curren sink for display backligh LEDs. If no used, connec o VOUT, bu do no leave open. If lef open, he IC works in 2 mode. LED5 and LED6 6 and 7 Curren sink for flash/orch LEDs. If no used, connec o VOUT, bu do no leave open. If lef open, he IC works in 2 mode. VIN 14 Power supply volage inpu. VOUT 2 Charge pump oupu volage source for display backligh and flash/orch LED anodes. Connec a 4.7 μf capacior, COUT, beween VOUT and (see figures 1 hrough 4). 3

4 ELECTRICAL CHARACTERISTICS a VIN = ENM = 3.6 V, ENF =, = = 1 μf, = COUT = 4.7 μf, RSET = 6.49 kω, T A = 40 C o +85 C; ypical values are a T A = 25 C; unless oherwise noed Characerisics Symbol Tes Condiions Min. Typ. Max. Unis Inpu Volage Range V IN V Undervolage Lockou Threshold V UVLO V IN falling V UVLO Hyseresis Window V UVLOHYS 60 mv Swiching in 1.5 or 2.0 mode; T A = 25 C 6 ma Quiescen Curren I Q ENF = ENM = ; T A = 25 C μa Sof-sar Compleion Time ss 2.0 ms Bias Volage V BIAS 0.6 V Leakage in Shudown V LKG μa Curren Range I SET μa o LEDx Curren Raio for LED1 hrough I LEDx /I 100% seing, I SET = 60 μa 220 A/A 100% Oupu Curren for LED5 and LED6 I LED56MAX Defaul 100% seing when ENF is enabled ma I LED Accuracy for LED1 hrough b E ILED14ERR ENF =, ENM = VIN ±1.6 % LED Curren Maching for LED1 hrough c ΔI LED14 ENF =, ENM = VIN ±0.5 % LED Curren Maching for LED5 and LED6 c ΔI LED56 ENF = VIN, ENM =, 100% ±0.5 % Regulaion Volage a LEDx (1.5 and 2 modes) V REG ENF = ENM = VIN 250 mv 1x mode o 1.5x or 1.5x o 2x mode ransiion volage a LEDx V rans V LEDx falling 150 mv Transiion Dropou Dela d ΔV dr Measured as V rans V dropou 40 mv Open Loop Oupu Resisance e R OUT 1.5 mode (1.5 V IN ) / I OUT 2.5 Ω 1 mode (V IN ) / I OUT 1 Ω 2 mode (2 V IN ) / I OUT 5 Ω LED Leakage in Shudown V LEDLKG ENF = ENM =, V IN = 5.5 V μa Oscillaor Frequency f osc 1 MHz Open circui a any LED ha is programmed Oupu Overvolage Proecion (guaraneed by design) V ovp o be in he ON sae 6.0 V ENF and ENM Inpu High Threshold V IH Inpu high logic hreshold 1.4 V ENF and ENM Inpu Low Threshold V IL Inpu low logic hreshold 0.4 V Inpu High Curren I IH V IH =VIN 1 μa Inpu Low Curren I IL V IL = 1 μa ENM and ENF Pulse Low Time (figure 6) LO μs ENM and ENF Pulse High Time (figure 6) HI 0.5 μs ENM and ENF Iniial Pulse High Time (figure 6) INIHI Firs ENM or ENF pulse afer shudown 50 μs Shudown or Rese Delay SHDN Falling edge of ENF and/or ENM 0.5 ms Thermal Shudown Threshold T TSD 20 o C hyseresis 165 o C a Specificaions for he range T A = 40 C o 85 C are guaraneed by design. b I LED accuracy is defined as ( I SET 220 I LEDAVG ) / (I SET 220). c LED curren maching is defined as (I LEDx I LEDAVG ) / I LEDAVG. d Dropou volage V dropou is defined as LEDx-o- volage a which I LEDx drops 10% below he value of I LEDx when V LEDx = 300 mv. e The open loop oupu resisance, R OUT, for 1.5 mode is measured when one of he LEDx pins is ied o ground or open (hus is volage is always less han 80 mv). 4

5 Performance Characerisics Tess performed using applicaion circui shown in figure 1 T A = 25 C, V IN = 3.6 V (unless oherwise noed) Efficiency versus Supply Volage for LED1 hrough, in parallel Efficiency versus Supply Volage for LED5 and LED6, in parallel V Fx = 3.7 V I Fx = 100 ma Eff (%) V Fx = 3.4 V I Fx = 20 ma Eff (%) V Fx = 3.1 V I Fx = 10 ma V Fx = 3.2 V I Fx = 50 ma V IN (V) V IN (V) Logic Level R SET versus I LED V ENx (V) V HI V LO I LED /Channel(mA) R SET = 6.65 kω R SET = 8.87 kω V IN (V) R SET (kω) on ENM Enable Pulses versus Toal Curren, LED1 hrough V ENM V ENM 0.5 V I LED14 50 ma ime 50 ms I LED14 5

6 Performance Characerisics Tess performed using applicaion circui shown in figure 1 T A = 25 C, V IN = 3.6 V (unless oherwise noed) LED5-6 ON, 1.5 mode V IN = 3.2 V, I OUT = 200 ma, V F = 3.1 V Ripple 20 mv C4 I IN Ripple 50 ma ime 500 ns C4 I IN LED5-6 ON, 2 mode V IN = 2.7 V, I OUT = 200 ma, V F = 3.1 V Ripple 20 mv C4 I IN Ripple 50 ma ime 500 ns C4 I IN LED1-4 ON, 1.5 mode V IN = 3.6 V, I OUT = 80 ma, V F = 3.4 V Ripple 20 mv C4 I IN Ripple 50 ma ime 500 ns C4 I IN 6

7 Performance Characerisics Tess performed using applicaion circui shown in figure 1 T A = 25 C Turn ON LED1-6 in 1X Mode V IN = 4.0 V, I OUT = 280 ma Turn ON LED1-6 in 2X mode V IN = 2.7 V, I OUT = 280 ma V ENF and V ENM V ENF and V ENM I OUT I OUT V ENF and V ENM 2.00 V 2.00 V I OUT 100 ma ime 0.5 ms V ENF and V ENM 2.00 V 2.00 V I OUT 100 ma ime 0.5 ms Turn ON LED1-6 in 1.5X Mode V IN = 3.0 V, I OUT = 280 ma V ENF and V ENM I OUT V ENF and V ENM 2.00 V 2.00 V I OUT 100 ma ime 0.5 ms 7

8 Applicaion Informaion Seing LED Curren Use he following formula o se he display backligh LED full curren (100%) using RSET on LED1 hrough. The maximum curren hrough one LED should no exceed 30 ma: ENM (LED1-4) or ENF (LED5-6) R SET = 0.6 V 220 / I LEDx where R SET is in Ω and I LEDx in amperes. The defaul flash/orch curren on LED5 and LED6 is se inernally o 100 ma per channel. When boh he display backligh and he flash/orch LEDs are on, he maximum curren oupu from LED1 hrough is 30 ma per channel. The oupu curren of he flash/orch LEDs (LED5 and LED6) can be adjused by serial dimming a he ENF pin wihin 1 ms afer ENF is pulled high. Transiions Beween 1 and 1.5 or 2 Modes The adapively selecs operaing mode. When V IN is sufficienly high o mainain V LEDx > 150 mv, he A8350 operaes Eff (%) V IN Falling V IN Rising HI(Ini) V IN (V) Figure 5. Mode change ransiions V Fx = 3.4 V I Fx = 20 ma in 1 mode unless, as V IN drops, he LEDx nodes fall below he 150 mv hreshold. When V LEDx falls below 150 mv, he IC eners 1.5 mode. When he swiches from 1 o 2 mode, i firs swiches o 1.5 mode for a ypical duraion of 1 ms before enering 2 mode. When operaing in 1.5 mode, if < V IN, hen he IC swiches back o 1 mode every 130 ms, and hen reeners 1.5 mode again if necessary. Transiions Beween 1.5 and 2 Modes The ransiion from 1.5 o 2 mode depends upon dropou condiions. When operaing in 2 mode, he IC swiches back o 1.5 mode every 130 ms, and hen reeners 2 mode again if necessary. Furhermore, when in 2 mode, whenever a channel disabling is sensed (ha is, whenever ENM is held low for > 0.5 ms wih ENF high, or vice versa), he IC auomaically revers o 1.5 mode, and hen reeners 2 mode again if necessary. Display Backligh LED1 hrough The display backligh LEDs (LED1 hrough ) brighness and on/off can be conrolled using digial inpu a he ENM pin. The ENM pin acceps one-wire serial pulse inpu o enable he A8350 and o se up o 11 dimming levels, from 100% down o 5%. When ENM is iniially pulled up from shudown, afer a sofsar, he curren for he backligh LEDs is programmed o 100% of he seing curren, which is deermined by he curren hrough he pin. Each subsequen pulse reduces he LED curren by 10%, and he 10h pulse reduces he curren by 5%. The nex pulse resores 100% (full) brighness. Figure 6 shows he iming diagram for ENM conrol SS LO HI SHDN I ILED(1-4) or I ILED(5-6) SHDN 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 5% 100% 90% SHDN or Rese Figure 6. Single-Wire Serial Conrol; a pins ENF and ENM. 8

9 Flash/Torch LED5 and LED6 Operaion The flash/orch LEDs (LED5 and LED6) brighness and on/off can be conrolled using digial inpu a ENF pin. ENF acceps one-wire serial pulse inpu o enable he and o se up o 11 dimming levels, from 100 ma (he defaul 100% level) down o 5 ma. When he ENF pin is iniially pulled up from shudown, afer a sof-sar (if he IC is no ye sof-sared using he ENM pin), he curren for LED5 and LED6 is, by defaul, programmed o 100 ma, corresponding o 100% of flash/orch brighness. Each subsequen pulse reduces he LED curren by 10 ma, and he 10h pulse reduces he curren by 5 ma. The nex pulse hen resores o 100 ma (full) oupu curren per channel. Figure 6 shows he iming diagram for ENF. Absolue Level Operaion Some applicaions require dimming o a specific level, regardless of he presen level of dimming. For example, if he IC should dim o 30%, his can be done wih 7 seps, as shown in figure 6, irrespecive of he dimming level in effec. This can be achieved by pulling corresponding ENx pin low for ime greaer han SHDN and hen applying pulses as shown in figure 6 (7 for 30% dimming). If he pulses are applied wihin 2 o 3 ms, he display flicker is no visible. The procedure is shown in figure 7. Shudown When he ENM pin is pulled low for 0.5 ms or longer, he display backligh channels are shu off and dimming is rese o 100% upon he nex ENM going high edge. When he ENF pin is pulled low for 0.5 ms or longer, he brighness of he flash/orch channels is rese o 100 ma upon he nex ENF going high edge. When boh ENM and ENF are pulled low for 0.5 ms or longer, he eners he shudown mode. Shor Circui Proecion The is proeced agains shor circuis on he oupu. When is exernally pulled below 1.2 V, he IC eners Shor Circui mode. The resumes normal operaion when he shor circui is removed. Rapid pulse paern > SHDN ENx pulled low V ENM V ENM 2.00 V 2.00 V I OUT 50 ma ime 0.5 ms 100% I SET couner reses 30% I OUT Figure 7. Absolue Level Seing. Wih ENM pulled low longer he SHDN, pulsing he corresponding ENx pin ses an absolue arge level. 9

10 + + Overvolage Proecion The is proeced up o 4.9 V supply volage, agains accidenal overvolage caused by an open LED. When any LED opens, will increase ill 6 V. Remaining LEDs will coninue o funcion normally. Normal operaion will be resumed when he faul is removed. LED Disconnecion Every LEDx pin has a disable subcircui, as shown in figure 8. The compares he volage on each LED pin, and if he volage on he pin is greaer han eiher 0.4 V or V IN 0.4 V, hen he corresponding LED pin is disabled. If any WLED is no used, connec he corresponding pin o VOUT. Never leave open any unused WLED pin. LED pins will sink 20 μa ypical when conneced o VOUT and he corresponding LED group (main or sub) is enabled. Noe: In shudown mode (ENM = ENS = 0 V for > 0.5 ms), he oal leakage curren is < 1μA. Thermal Shudown The IC is inernally proeced agains overemperaure. The overemperaure limi is se o 165 C nominal. The IC shus down when he juncion emperaure exceeds 165 C and auomaically urns on again when he IC cools. Componen Selecion Ceramic capaciors wih X5R or X7R dielecric are recommended for he inpu capacior,, he oupu capacior, COUT, and he charge pump capaciors, and. VBATT VIN 1, 1.5, 2 Charge Pump VOUT COUT LED Disable Block One of six blocks V IN 0.4 LED1 D1 0.4 Curren Sink D2 D3 D4 D5 D6 Figure 8. LED disable subcircui. Subcircui for one LEDx pin shown. A similar block is conneced o each LEDx pin. 10

11 Package ES, 3 3 mm 16-Pin QFN/MLP ± A ± X D 0.08 C SEATING PLANE 0.75 ±0.05 C C 3.10 PCB Layou Reference View B 1.70 A For reference only (reference JEDEC MO-220WEED) Dimensions in millimeers Exac case and lead configuraion a supplier discreion wihin limis shown Terminal #1 mark area B Exposed hermal pad (reference only, erminal #1 idenifier appearance a supplier discreion) C Reference land paern layou (reference IPC7351 QFN50P300X300X80-17W4M); All pads a minimum of 0.20 mm from all adjacen pads; adjus as necessary o mee applicaion process requiremens and PCB layou olerances; when mouning on a mulilayer PCB, hermal vias a he exposed hermal pad land can improve hermal dissipaion (reference EIA/JEDEC Sandard JESD51-5) D Coplanariy includes exposed hermal pad and erminals Copyrigh , The producs described here are manufacured under one or more U.S. paens or U.S. paens pending. reserves he righ o make, from ime o ime, such de par ures from he deail spec i fi ca ions as may be required o permi improvemens in he per for mance, reliabiliy, or manufacurabiliy of is producs. Before placing an order, he user is cauioned o verify ha he informaion being relied upon is curren. Allegro s producs are no o be used in life suppor devices or sysems, if a failure of an Allegro produc can reasonably be expeced o cause he failure of ha life suppor device or sysem, or o affec he safey or effeciveness of ha device or sysem. The in for ma ion in clud ed herein is believed o be ac cu rae and reliable. How ev er, assumes no responsibiliy for is use; nor for any in fringe men of paens or oher righs of hird paries which may resul from is use. For he laes version of his documen, visi our websie: 11

Discontinued Product

Discontinued Product Disconinued Produc This device is no longer in producion. The device should no be purchased for new design applicaions. Samples are no longer available. Dae of saus change: November 1, 2010 Recommended