A8530EESTR-T

A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Features and Benefits ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ Proprietary adaptive control scheme (1×, 1.5×, 2×) 0.5% typical LED current matching 2 separate serial interfaces for dimming control Drives up to 6 white LEDs (4 display backlight, 2 flash/torch) 30 mA per LED channel for display backlight 100 mA per LED channel for flash/torch backlight 320 mA total output current capability Low EMI design and soft-start function Short circuit, overvoltage, thermal shutdown protection 0.75 mm very thin profile, 3 mm × 3 mm package Description The A8530 high efficiency charge pump ICs offer a simple, low-cost white LED driver solution for driving four display backlight and two flash/torch/video mode white LEDs. Using a proprietary control scheme (1×, 1.5×, and 2×), the A8530 can deliver well-matched LED current while maintaining the highest efficiency and low EMI. The LED current is regulated over the entire range of Li+ battery voltage to provide uniform intensity. LED brightness and on/off can be controlled for 4 display backlight LEDs and 2 flash/torch LEDs through 2 single-wire serial interface pins. The A8530 is available in a very thin profile (0.75 mm nominal height) 3 mm× 3 mm QFN/MLP 16 pin package. Applications include: ▪ ▪ ▪ ▪ White LED backlights for cellular phones, PDAs Digital cameras, camcorders Other portable device white LED backlighting 320 mA WLED flash/torch Package: 16 pin QFN/MLP (suffix ES) Approximate Scale 1:1 Typical Applications VBATT 2.7 to 5.5 V CIN 4.7 µF C1 1 µF C2 1 µF VIN C1+ C1– VOUT LED1 D1 D2 D3 D4 D5 D6 RSET On/Off and Dimming Control C2 1 µF COUT 4.7 µF VBATT 2.7 to 5.5 V CIN 4.7 µF C1 1 µF VIN C1+ C1– VOUT LED1 D1 COUT 4.7 µF LED2 C2+ A8530 LED3 C2– LED4 ISET ENM ENF GND LED5 LED6 LED2 C2+ A8530 LED3 C2– LED4 ISET ENM ENF GND LED5 LED6 RSET On/Off and Dimming Control D5 D6 D1-D4 Backlight; D5-D6 Flash D1-D4 Backlight; D5-D6 Flash Figure 1. 4 × 30 mA backlight with 2 × 100 mA flash VBATT 2.7 to 5.5 V CIN 4.7 µF C1 1 µF C2 1 µF COUT 4.7 µF D1 VBATT Figure 2. 3 × 100 mA flash VIN C1+ C1– VOUT LED1 VIN CIN 1 μF C1+ C1– VOUT LED1 D1 D2 D3 D4 D5 D6 LED2 C2+ A8530 LED3 C2– LED4 ISET ENM ENF GND LED5 LED6 RSET On/Off and Dimming Control LED2 C2+ A8530 LED3 C2– LED4 ISET ENM ENF GND LED5 LED6 RSET On/Off and Dimming Control D1-D4 Main; D5-D6 Flash VIN>Vf(max)+0.2 V, Vf = LED forward drop Figure 3. 320 mA flash 8530-DS Figure 4. High efficiency current sink A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Functional Block Diagram C1 1 µF C1+ C1 – C2+ C2 1 µF C2– VIN Fractional Charge Pump (1×, 1.5×, and 2×) + – VOUT CIN 4.7 µF ENM Control, Clock, and Reference COUT 4.7 µF ENF Minimum Select LED1 LED2 LED3 Current Mirror LED4 LED5 IREF IREF LED6 + – ISET + – + – + – + – + – + – RSET GND Absolute Maximum Ratings Input or Output Voltage VIN, VOUT, C1+, C1– , C2+, C2– to GND ..................... –0.3 to 6 V All other pins..................................................... –0.3 to VIN + 0.3 V VOUT Short Circuit to GND .................................................... Continuous Operating Ambient Temperature, TA ..................................... –40°C to 85°C Junction Temperature, TJ(max).............................................................. 150°C Storage Temperature, TS ................................................... –55°C to 150°C Package Thermal Characteristics Package Thermal Resistance, RθJA = 68 °C/W (vendor data, on 4-layer PCB; unverified) Device package is lead (Pb) free, with 100% matte tin leadframe plating. Use the following complete part number when ordering: Part Number A8530EESTR-T Packaging* 7-in. reel, 1500 pieces/reel Package Type ES, 3 × 3 mm MLP-16 *Contact Allegro for additional packing options. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Pin-out Diagram ES Package 16 C1+ 15 C2– C2+ VOUT ISET ENF 1 2 3 4 5 6 7 8 EP 13 C1– 12 GND 11 LED1 10 LED2 9 LED3 LED4 ENM LED6 (Top View) Terminal List Table Name C1– C1+ C2– C2+ ENF ENM EP GND ISET LED1, LED2, LED3, and LED4 LED5 and LED6 VIN VOUT Number 13 16 15 1 4 5 – 12 3 8, 9, 10, and 11 6 and 7 14 2 Function Negative terminal of capacitor C1. Connect capacitor C1 between C1+ and C1–. Positive terminal of capacitor C1. Negative terminal of capacitor C2 Positive terminal of capacitor C2. Connect capacitor C2 between C2+ and C2–. Enable and dimming control input for flash/torch. Enable and dimming control input for display backlight. Exposed metal pad on bottom side. Connect this to ground plane for better thermal performance. Ground. Connect RSET resistor to ground to set desired constant current through backlight LEDs. ILED(max) = 220 x 0.6 V / RSET Current sink for display backlight LEDs. If not used, connect to VOUT, but do not leave open. If left open, the IC works in 2 × mode. Current sink for flash/torch LEDs. If not used, connect to VOUT, but do not leave open. If left open, the IC works in 2 × mode. Power supply voltage input. Charge pump output voltage source for display backlight and flash/torch LED anodes. Connect a 4.7 μF capacitor, COUT, between VOUT and GND (see figures 1 through 4). LED5 14 VIN Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver ELECTRICAL CHARACTERISTICSa VIN = ENM = 3.6 V, ENF = GND, C1 = C2 = 1 μF, CIN = COUT = 4.7 μF, RSET = 6.49 kΩ, TA = –40°C to +85°C; typical values are at TA = 25°C; unless otherwise noted Characteristics Input Voltage Range Undervoltage Lockout Threshold UVLO Hysteresis Window Quiescent Current Soft-start Completion Time ISET Bias Voltage ISET Leakage in Shutdown ISET Current Range ISET to LEDx Current Ratio for LED1 through LED4 100% Output Current for LED5 and LED6 ILED Accuracy for LED1 through LED4b LED Current Matching for LED1 through LED4c LED Current Matching for LED5 and LED6c Regulation Voltage at LEDx (1.5 × and 2 × modes) 1x mode to 1.5x or 1.5x to 2x mode transition voltage at LEDx Transition–Dropout Deltad Open Loop Output Resistancee LED Leakage in Shutdown Oscillator Frequency Output Overvoltage Protection (guaranteed by design) ENF and ENM Input High Threshold ENF and ENM Input Low Threshold Input High Current Input Low Current ENM and ENF Pulse Low Time (figure 6) ENM and ENF Pulse High Time (figure 6) ENM and ENF Initial Pulse High Time (figure 6) Shutdown or Dimming Reset Delay Thermal Shutdown Threshold aSpecifications Symbol VIN VUVLO VUVLOHYS IQ tss VISETBIAS VISETLKG ISET ILEDx/IISET ILED56MAX ΔILED14 ΔILED56 VREG Vtrans ΔVdr ROUT VLEDLKG fosc Vovp VIH VIL IIH IIL tLO tHI tINIHI tSHDN TTSD VIN falling Test Conditions Min. 2.7 2.25 – – – – – – 40 – 92 – – – – – – – – – – – Typ. Max. Units – 5.5 V 2.45 60 6 0.1 2.0 0.6 0.01 – 220 100 ±1.6 ±0.5 ±0.5 250 150 40 1 2.5 5 0.01 1 – – – – – – – – 0.5 165 2.60 – – 2 – – 1 140 – 108 – – – – – – – – – 1 – 6.0 – 0.4 1 1 250 – – – – V mV mA μA ms V μA μA A/A mA % % % mV mV mV Ω Ω Ω μA MHz V V V μA μA μs μs μs ms oC Switching in 1.5 × or 2.0 × mode; TA = 25°C ENF = ENM = GND; TA = 25°C 100% setting, ISET = 60 μA Default 100% setting when ENF is enabled ENF = GND, ENM = VIN ENF = VIN, ENM = GND, 100% ENF = ENM = VIN VLEDx falling Measured as Vtrans – Vdropout 1× mode (VIN – VOUT) / IOUT 1.5× mode (1.5 × VIN – VOUT) / IOUT 2× mode (2 × VIN – VOUT) / IOUT ENF = ENM = GND, VIN = 5.5 V Open circuit at any LED that is programmed to be in the ON state Input high logic threshold Input low logic threshold VIH=VIN VIL= GND EILED14ERR ENF = GND, ENM = VIN – 1.4 – – – 0.5 0.5 First ENM or ENF pulse after shutdown Falling edge of ENF and/or ENM 20oC hysteresis 50 – – for the range TA = –40°C to 85°C are guaranteed by design. bI LED accuracy is defined as ( ISET × 220 – ILEDAVG ) / (ISET × 220). cLED current matching is defined as (I LEDx – ILEDAVG) / ILEDAVG . dDropout voltage V dropout is defined as LEDx-to-GND voltage at which ILEDx drops 10% below the value of ILEDx when VLEDx = 300 mV. eThe open loop output resistance, R OUT, for 1.5 × mode is measured when one of the LEDx pins is tied to ground or open (thus its voltage than 80 mV). is always less Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Tests performed using application circuit shown in figure 1 TA = 25°C, VIN = 3.6 V (unless otherwise noted) Performance Characteristics Efficiency versus Supply Voltage for LED1 through LED4, in parallel 95 90 85 80 95 90 85 Efficiency versus Supply Voltage for LED5 and LED6, in parallel VFx = 3.7 V IFx = 100 mA Eff (%) 75 70 65 60 55 2.7 3.1 3.5 3.9 VIN (V) 4.3 Eff (%) VFx = 3.4 V IFx = 20 mA 80 75 70 VFx = 3.1 V IFx = 10 mA 65 60 55 4.7 5.1 5.5 2.7 3.1 3.5 3.9 VIN (V) 4.3 VFx = 3.2 V IFx = 50 mA 4.7 5.1 5.5 Logic Level 1.2 1.1 1.0 ILED / Channel (mA) 35 30 RSET versus ILED VHI 25 20 15 10 5 0 RSET = 6. RSET = V ENx (V) 0.9 0.8 0.7 0.6 0.5 2.7 3.1 3.5 3.9 VIN (V) 4.3 4.7 5.1 5.5 VLO 4 6 8 10 RSET ( 12 14 16 Dimming on ENM Enable Pulses versus Total Current, LED1 through LED4 VENM C1 ILED14 Symbol C1 C2 t Parameter VENM ILED14 time Units/Division 0.5 V 50 mA 50 ms C2 t Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 5 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Tests performed using application circuit shown in figure 1 TA = 25°C, VIN = 3.6 V (unless otherwise noted) Performance Characteristics LED5-6 ON, 1.5× mode VIN = 3.2 V, IOUT = 200 mA, VF = 3.1 V C3 VOUT Symbol C3 C4 t Parameter Units/Division 20 mV VOUT Ripple IIN Ripple 50 mA time 500 ns IIN C4 t LED5-6 ON, 2× mode VIN = 2.7 V, IOUT = 200 mA, VF = 3.1 V C3 VOUT Symbol C3 C4 t Parameter Units/Division VOUT Ripple 20 mV 50 mA IIN Ripple time 500 ns IIN C4 t LED1-4 ON, 1.5× mode VIN = 3.6 V, IOUT = 80 mA, VF = 3.4 V C3 VOUT VOUT Symbol C3 C4 t Parameter Units/Division VOUT Ripple 20 mV IIN Ripple 50 mA time 500 ns IIN C4 t Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Tests performed using application circuit shown in figure 1 TA = 25°C Performance Characteristics Turn ON LED1-6 in 1X Mode VIN = 4.0 V, IOUT = 280 mA VENF and VENM Turn ON LED1-6 in 2X mode VIN = 2.7 V, IOUT = 280 mA VENF and VENM C1 VOUT C1 VOUT C2 IOUT IOUT C2 C3 C3 t t Symbol C1 C2 C3 t Parameter Units/Division VENF and VENM 2.00 V 2.00 V VOUT IOUT 100 mA time 0.5 ms Symbol C1 C2 C3 t Parameter Units/Division VENF and VENM 2.00 V 2.00 V VOUT IOUT 100 mA time 0.5 ms Turn ON LED1-6 in 1.5X Mode VIN = 3.0 V, IOUT = 280 mA VENF and VENM VOUT C1 IOUT C2 C3 t Symbol C1 C2 C3 t Parameter Units/Division VENF and VENM 2.00 V 2.00 V VOUT IOUT 100 mA time 0.5 ms Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 7 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Application Information Setting LED Current Use the following formula to set the display backlight LED full current (100%) using RSET on LED1 through LED4. The maximum current through one LED should not exceed 30 mA: RSET = 0.6 V × 220 / ILEDx where RSET is in Ω and ILEDx in amperes. The default flash/torch current on LED5 and LED6 is set internally to 100 mA per channel. When both the display backlight and the flash/torch LEDs are on, the maximum current output from LED1 through LED4 is 30 mA per channel. The output current of the flash/torch LEDs (LED5 and LED6) can be adjusted by serial dimming at the ENF pin within 1 ms after ENF is pulled high. Transitions Between 1× and 1.5× or 2× Modes The A8530 adaptively selects operating mode. When VIN is sufficiently high to maintain VLEDx > 150 mV, the A8350 operates 95 90 85 in 1 × mode unless, as VIN drops, the LEDx nodes fall below the 150 mV threshold. When VLEDx falls below 150 mV, the IC enters 1.5× mode. When the A8530 switches from 1× to 2× mode, it first switches to 1.5× mode for a typical duration of 1 ms before entering 2× mode. When operating in 1.5× mode, if VOUT < VIN, then the IC switches back to 1× mode every 130 ms, and then reenters 1.5× mode again if necessary. Transitions Between 1.5× and 2× Modes The transition from 1.5× to 2× mode depends upon dropout conditions. When operating in 2× mode, the IC switches back to 1.5× mode every 130 ms, and then reenters 2× mode again if necessary. Furthermore, when in 2× mode, whenever a channel disabling is sensed (that is, whenever ENM is held low for > 0.5 ms with ENF high, or vice versa), the IC automatically reverts to 1.5× mode, and then reenters 2× mode again if necessary. Dimming Display Backlight LED1 through LED4 Dimming The display backlight LEDs (LED1 through LED4) brightness and on/off can be controlled using digital input at the ENM pin. The ENM pin accepts one-wire serial pulse input to enable the A8350 and to set up to 11 dimming levels, from 100% down to 5%. When ENM is initially pulled up from shutdown, after a softstart, the current for the backlight LEDs is programmed to 100% of the setting current, which is determined by the current through the ISET pin. Each subsequent pulse reduces the LED current by 10%, and the 10th pulse reduces the current by 5%. The next pulse restores 100% (full) brightness. Figure 6 shows the timing diagram for ENM control. 6 7 8 9 10 11 VIN Falling 80 Eff (%) 70 65 60 55 2.7 3.1 3.5 3.9 VIN (V) VIN Rising 75 VFx = 3.4 V IFx = 20 mA 4.3 4.7 5.1 5.5 Figure 5. Mode change transitions tHI(Init) ENM (LED1-4) or ENF (LED5-6) 0 1 2 3 4 5 tSS IILED(1-4) or IILED(5-6) SHDN 100% 90% 80% 70% t LO t HI 100% 90% tSHDN 60% 50% 40% 30% 20% 10% 5% SHDN or Dimming Reset Figure 6. Single-Wire Serial Dimming Control; at pins ENF and ENM. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Flash/Torch LED5 and LED6 Operation The flash/torch LEDs (LED5 and LED6) brightness and on/off can be controlled using digital input at ENF pin. ENF accepts one-wire serial pulse input to enable the A8530 and to set up to 11 dimming levels, from 100 mA (the default 100% level) down to 5 mA. When the ENF pin is initially pulled up from shutdown, after a soft-start (if the IC is not yet soft-started using the ENM pin), the current for LED5 and LED6 is, by default, programmed to 100 mA, corresponding to 100% of flash/torch brightness. Each subsequent pulse reduces the LED current by 10 mA, and the 10th pulse reduces the current by 5 mA. The next pulse then restores to 100 mA (full) output current per channel. Figure 6 shows the timing diagram for ENF. Absolute Level Operation Some applications require dimming to a specific level, regardless of the present level of dimming. For example, if the IC should dim to 30%, this can be done with 7 steps, as shown in figure 6, irrespective of the dimming level in effect. This can be achieved by pulling corresponding ENx pin low for time greater than tSHDN and then applying pulses as shown in figure 6 (7 for 30% dimming). If the pulses are applied within 2 to 3 ms, the display flicker is not visible. The procedure is shown in figure 7. Shutdown When the ENM pin is pulled low for 0.5 ms or longer, the display backlight channels are shut off and dimming is reset to 100% upon the next ENM going high edge. When the ENF pin is pulled low for 0.5 ms or longer, the brightness of the flash/torch channels is reset to 100 mA upon the next ENF going high edge. When both ENM and ENF are pulled low for 0.5 ms or longer, the A8530 enters the shutdown mode. Short Circuit Protection The A8530 is protected against short circuits on the output. When VOUT is externally pulled below 1.2 V, the IC enters Short Circuit mode. The A8530 resumes normal operation when the short circuit is removed. Rapid pulse pattern Δt > tSHDN C1 ENx pulled low VENM Symbol C1 C2 C3 t Parameter VENM VOUT IOUT time Units/Division 2.00 V 2.00 V 50 mA 0.5 ms C2 VOUT 100% C3 ISET counter resets 30% IOUT t Figure 7. Absolute Dimming Level Setting. With ENM pulled low longer the tSHDN, pulsing the corresponding ENx pin sets an absolute target level. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 9 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Overvoltage Protection The A8530 is protected up to 4.9 V supply voltage, against accidental overvoltage caused by an open LED. When any LED opens, VOUT will increase till 6 V. Remaining LEDs will continue to function normally. Normal operation will be resumed when the fault is removed. LED Disconnection Every LEDx pin has a disable subcircuit, as shown in figure 8. The A8530 compares the voltage on each LED pin, and if the voltage on the pin is greater than either VOUT – 0.4 V or VIN – 0.4 V, then the corresponding LED pin is disabled. Thermal Shutdown The IC is internally protected against overtemperature. The overtemperature limit is set to 165°C nominal. The IC shuts down when the junction temperature exceeds 165°C and automatically turns on again when the IC cools. Component Selection Ceramic capacitors with X5R or X7R dielectric are recommended for the input capacitor, CIN, the output capacitor, COUT, and the charge pump capacitors, C1 and C2. A8530 VBATT CIN VIN 1×, 1.5×, 2× Charge Pump VOUT COUT LED Disable Block One of six blocks – + – + VOUT – 0.4 Current Sink VIN – 0.4 LED1 D1 D2 D3 D4 D5 D6 Figure 8. LED disable subcircuit. Subcircuit for one LEDx pin shown. A similar block is connected to each LEDx pin. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 10 A8530 Ultracompact 6-Channel Backlight and Flash/Torch White LED Driver Package ES, 3 × 3 mm 16-Pin QFN/MLP 3.15 .124 2.85 .112 16 Preliminary dimensions, for reference only (reference JEDEC MO-220WEED-4) Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Terminal #1 mark area B Exposed thermal pad (reference only, terminal #1 identifier appearance at supplier discretion) C Reference land pattern layout (reference IPC7351 QFN50P300X300X80-17W4M); adjust as necessary to meet application process requirements and PCB layout tolerances; when mounting on a multilayer PCB, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5) 16X 0.08 [.003] C 16X 0.30 .012 0.18 .007 0.10 [.004] M C A B 0.05 [.002] M C 0.50 .020 0.30 .012 NOM 0.90 .035 NOM C 1 12X 0.20 .008 MIN 1.70 .067 NOM 0.50 .020 0.30 .012 3.10 .122 NOM 2 1 B 16 0.50 .020 NOM 1.70 .067 NOM 1 2 A B A 3.15 .124 2.85 .112 SEATING PLANE 0.80 .031 0.70 .028 0.20 .008 REF 0.05 .002 0.00 .000 C 1.70 NOM .067 4X 0.20 .008 MIN 1.70 .067 NOM 3.10 .122 NOM 16 4X 0.20 .008 MIN 0.23 x 0.23 .009 x .009 REF The products described here are manufactured under one or more U.S. patents or U.S. patents pending. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detailed specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro products are not authorized for use as critical components in life-support devices or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. Copyright©2005, 2006 Allegro MicroSystems, Inc. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 11