AAT2861IMK-2-T1

PRODUCT DATASHEET AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Features • Input Voltage Range: 2.7V to 5.5V • AS2Cwire Serial Interface • Tri-Mode Charge Pump ▪ Drives up to Eight LEDs (Backlight/Flash) • Programmable Backlight Current Settings ▪ 31mA Maximum Current per Channel ▪ 32 Linear Current Settings ▪ Independent Main/Sub Settings ▪ Programmable Fade-In and Fade-Out • Programmable Flash Current ▪ 600mA Total Flash Current ▪ 16 Linear Current Settings ▪ 1- or 2-Channel Configuration • 1MHz Switching Frequency • Automatic Soft-Start • Three Linear Low Dropout Regulators ▪ 300mA Output Current ▪ 150mV Dropout ▪ Programmable Output Voltage from 1.2V to 3.3V ▪ Output Auto-Discharge for Fast Shutdown • Built-In Thermal Protection • Automatic Soft Start • -40°C to +85°C Temperature Range • TQFN34-24 Package General Description The AAT2861 is a highly integrated charge pump-based lighting management unit (LMU) offering eight LED channels with three linear regulators optimized for single-cell lithium-ion/polymer systems. The charge pump provides power for all LED outputs; multiple backlight and flash LED configurations are available. The backlight LED outputs can be programmed up to 31mA each and the flash LED output current can be programmed up to 600mA total. AnalogicTech’s AS2Cwire™ (Advanced Simple Serial Control™) single-wire interface is used to enable, disable, and set the current to one of 32 levels for the backlight and one of 16 levels for the flash. A programmable safety timer and separate flash control input are included for easy flash control. Backlight current matching is better than 3% for uniform display brightness, and flash current matching is better than 5% for uniform power dissipation. The AAT2861 also offers three high-performance lownoise MicroPower™ LDO linear regulators. The regulators output voltages are set through the AS2Cwire serial interface. Each LDO can supply up to 300mA load current and ground-pin current is only 80μA, making the AAT2861 ideal for battery-operated applications. The AAT2861 is available in a Pb-free, space-saving TQFN34-24 package and operates over the -40°C to +85°C ambient temperature range. Applications • Camera Enabled Mobile Devices • Digital Still Cameras • Multimedia Mobile Phones Typical Application CF1 1µF C1+ IN VBAT 3.6V CIN 2.2µF IN EN/SET FL_EN EN_ LDOA EN_ LDOB/C BL1 BL2 BL3 BL4 FL_EN BL5 BL6 EN_ LDOA BL7/FL2 FL1 EN_LDOB/C EN/SET LDOA LDOB LDOC AGND PGND CF2 1µF C2OUT C1- C2+ WLEDs OSRAM LW M673 or equivalent VOUT COUT 2.2µF Flash LEDs Lumiled LXCL-PWF1 or equivalent AAT2861-x V LDOC at 300mA C LDOC 2.2µF V LDOB at 300mA C LDOB 2.2µF V LDOA at 300mA C LDOA 2.2µF 2861.2009.02.1.2 www.analogictech.com 1 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Pin Descriptions Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Symbol OUT C2+ EN/SET FL_EN EN_LDOA EN_LDOB/C AGND LDOC IN LDOB LDOA BL1 BL2 BL3 BL4 BL5 BL6 Description Charge pump output. OUT is the output of the charge pump and supplies current to the backlight and flash LEDs. Connect the backlight and flash LED anodes to OUT. Bypass OUT to PGND with a 2.2μF or larger ceramic capacitor as close to the AAT2861 as possible. Positive terminal of charge pump capacitor 2. Connect the 1μF charge pump capacitor 2 from C2+ to C2-. AS2Cwire serial input. EN/SET is the address and data input of the AS2Cwire serial interface. AS2Cwire is used to control backlight, flash and LDO functions. Flash enable. FL_EN is the enable control for the Flash LEDs. For the FL_EN pin to enable the flash current, the EN/SET pin must also be pulled high. LDO A enable pin. EN_LDOA turns on or off LDO regulator A. The EN/SET pin must also be pulled high for LDO A to be enabled. The EN_LDOA input can be overwritten via the AS2Cwire interface to disable LDO A. LDO B and LDO C enable pin. EN_LDOB/C enables both LDO regulators B and C. The EN/SET pin must also be pulled high for the LDO regulators to be enabled. The EN_LDOB/C input can be overwritten via the AS2Cwire interface to disable either LDO B or LDO C. Analog ground. Connect AGND to PGND at a single point as close to the AAT2861 as possible. LDOC is the voltage output of LDO C. Bypass LDOC to AGND with a 2.2μF or larger capacitor as close to the AAT2861 as possible. Input power pin for all three LDOs. Connect Pin 9 to Pin 23 with as short a PCB trace as practical. LDOB is the voltage output of LDO B. Bypass LDOB to AGND with a 2.2μF or greater capacitor as close to the AAT2861 as possible. LDOA is the voltage output of LDO A. Bypass LDOA to AGND with a 2.2μF or larger ceramic capacitor as close to the AAT2861 as possible. Backlight LED 1 current sink. BL1 controls the current through backlight LED 1. Connect the cathode of backlight LED 1 to BL1. If not used, connect BL1 to OUT. Backlight LED 2 current sink. BL2 controls the current through backlight LED 2. Connect the cathode of backlight LED 2 to BL2. If not used, connect BL2 to OUT. Backlight LED 3 current sink. BL3 controls the current through backlight LED 3. Connect the cathode of backlight LED 3 to BL3. If not used, connect BL3 to OUT. Backlight LED 4 current sink. BL4 controls the current through backlight LED 4. Connect the cathode of backlight LED 4 to BL4. If not used, connect BL4 to OUT. Backlight LED 5 current sink. BL5 controls the current through backlight LED 5. Connect the cathode of backlight LED 5 to BL5. If not used, connect BL5 to OUT. Backlight LED 6 current sink. BL6 controls the current through backlight LED 6. Connect the cathode of backlight LED 6 to BL6. If not used, connect BL6 to OUT. AAT2861-1/3: Backlight LED 7 current sink. BL7 controls the current through backlight LED 7. Connect the cathode of backlight LED 7 to BL7. If not used, connect BL7 to OUT. AAT2861-2: Flash LED 2 current sink. FL2 controls the current through Flash LED 2. Connect the cathode of Flash LED 2 to FL2. If not used, connect FL2 to OUT. Flash LED 1 current sink. FL1 controls the current through Flash LED 1. Connect the cathode of Flash LED 1 to FL1. If not used, connect FL1 to OUT. Power ground. Connect PGND to AGND at a single point as close to the AAT2861 as possible. Negative terminal of charge pump capacitor 2. Negative terminal of charge pump capacitor 1. Power input. Connect IN to the input source voltage. Bypass IN to PGND with a 2.2μF or larger ceramic capacitor as close to the AAT2861 as possible. Positive terminal of charge pump capacitor 1. Connect the 1μF charge pump capacitor 1 from C1+ to C1-. Exposed paddle (bottom) Connect to PGND/AGND. 18 BL7 (FL2) 19 20 21 22 23 24 EP FL1 PGND C2C1IN C1+ 2 www.analogictech.com 2861.2009.02.1.2 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Pin Configuration TQFN34-24 (Top View) PGND C2C1IN C1+ 24 23 22 21 20 19 18 17 16 15 14 13 8 9 10 11 12 OUT C2+ EN/SET FL_EN EN_LDOA EN_LDOB/C AGND 1 2 3 4 5 6 7 FL1 BL7 (FL2) BL6 BL5 BL4 BL3 BL2 BL1 LDOA LDOB IN LDOC Part Number Descriptions1 Backlight LED Outputs Part Number AAT2861IMK-1-T1 AAT2861IMK-2-T1 AAT2861IMK-3-T1 Main 4 4 5 Sub 3 2 2 Flash LED Outputs 1 2 1 Absolute Maximum Ratings2 Symbol Description IN, OUT, BL1, BL2, BL3, BL4, BL5, BL6, BL7/FL2, FL1 Voltage to AGND C1+, C2+ Voltage to AGND C1-, C2-, LDOA, LDOB, LDOC, EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Voltage to AGND PGND Voltage to AGND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value -0.3 to 6.0 -0.3 to VOUT + 0.3 -0.3 to VIN + 0.3 -0.3 to 0.3 -40 to 150 300 Units V V V V °C °C TJ TLEAD Thermal Information3,4 Symbol PD θJA Description Maximum Power Dissipation Maximum Thermal Resistance Value 2.0 50 Units W °C/W 1. Backlight and Flash Configuration within a part number is configured though the AS2Cwire serial interface. For example, disabling the “Main Equals Sub” feature (Address 8, Data 5 - 8) in the AAT2861-1 will configure BL1-BL4 LED outputs as MAIN and BL5-BL7 outputs as SUB. 2. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 3. Derate 20mW/°C above 25°C ambient temperature. 4. Mounted on a FR4 circuit board. 2861.2009.02.1.2 www.analogictech.com 3 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Electrical Characteristics1 VIN = 3.6V; CIN = COUT = 2.2μF; C1 = C2 = 1μF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol VIN Description Conditions EN/SET = IN, BL1-BL7 = IN, FL_EN = EN_LDOA = EN_LDOB/C = AGND 2X Mode; EN/SET = IN, FL_EN = EN_LDOA = EN_LDOB/C = AGND; BL1-BL7 = OPEN EN/SET = EN_LDOA = EN_LDOB/C = IN; FL_EN = AGND; ADDR = 3; DATA = 1; No Load EN/SET = EN_LDOA = IN; FL_EN = EN_LDOB/C = AGND, ADDR = 3; DATA = 1; No Load EN/SET, FL_EN, EN_LDOA, EN_LDOB/C = AGND Min 2.7 Typ Max 5.5 600 5.5 225 80 1.0 Units V μA mA μA μA μA °C °C V mA V V MHz μs IN Operating Voltage Range IN Operating Current (1x mode, Main Channels enabled, IBLX not included) IN Operating Current (2x mode, Main Channels enabled, IBLX not included) IIN IN Operating Current (LDOA, LDOB and LDOC enabled) IN Operating Current (Only LDOA enabled) IN Shutdown Current IIN(SHDN) Over-Temperature Shutdown Threshold TSD Over-Temperature Shutdown Hysteresis TSD(HYS) Charge Pump Section OUT Output Voltage VOUT OUT Maximum Output Current IOUT(MAX) BL1-BL7 Charge Pump Mode Transition VIN(TH_H, BL) Hysteresis FL1-FL2 Charge Pump Mode Transition VIN(TH_H, FL) Hysteresis Charge Pump Oscillator Frequency fOSC Charge Pump Soft-Start Time tCP(SS) BL1-BL6, BL7/FL2, FL1 LED Drivers IBLx IBL_x ΔI(BLx)/ IBL(AVG) VBL_(TH) tFADE IFL[1] IFL[1](DATA13) ΔI(FLx)/ IFL(AVG) VFL[1/2](TH) ΔtFL/tFL_SET BL1-BL7 Current Accuracy BL1-BL7 Current Accuracy BL1-BL7 Current Matching2 BL1-BL7 Charge Pump Transition Threshold BL1-BL7 Automatic Fade-In/Fade-Out Timer FL1 Current Accuracy FL1 Current Accuracy FL1-FL2 Current Matching (AAT2861-2 only) FL1 Charge Pump Transition Threshold Flash Safety Timer Period 140 15 5.2 800 0.3 1 1 100 18 1.6 20 2 3 0.2 0.75 540 108 1 600 120 5 0.45 1.5 2 2.5 1.25 660 132 22 2.4 VIN = 3.0V, VOUT = 4.0 EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA = 16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12 EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR = 10, DATA = 1 TA = 25°C TA = 25°C EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA = 16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12 EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA = 16; ADDR = 3, DATA = 4; ADDR = 2, DATA = 14 EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA = 16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12 EN/SET = IN; VIN – VF = 1V; ADDR=0, DATA = 16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12 EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA = 16; ADDR = 1, DATA = 1; ADDR = 2, DATA = 12; ADDR = 3, DATA = 3 EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR = 10, DATA = 1 EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR = 10, DATA = 13 EN/SET = FL_EN = IN; VIN – VF = 1V, ADDR = 10, DATA = 1 EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR = 10, DATA = 1 EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR = 11, DATA = 1 mA mA % V s mA mA % V s 1. The AAT2861 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. Current matching is defined as the deviation of any sink current from the average of all active channels. 4 www.analogictech.com 2861.2009.02.1.2 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Electrical Characteristics (continued)1 VIN = 3.6V; CIN = COUT = 2.2μF; C1 = C2 = 1μF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Linear Regulators ΔVLDO[A/B/C]/ VLDO[A/B/C] LDOA, LDOB, LDOC Output Voltage Tolerance ILDO = 1mA to 200mA; TA = 25°C ILDO = 1mA to 200mA; TA = -40°C to +85°C VLDO[A/B/C] ≥ 3.0V; ILDO = 150mA VIN = (VLDO[A/B/C] + 1V) to 5V ILDO[A/B/C] = 10mA, 1kHz -1.5 -3.0 200 75 0.09 50 20 1.4 0.4 -1 1 500 500 75 50 75 150 1.5 3.0 % % mA mV %/V dB Ω V V μA μs μs μs ns μs Description Conditions Min Typ Max Units ILDO[A/B/C](MAX) LDOA, LDOB, LDOC Load Current VLDO[A/B/C](DO) LDOA, LDOB, LDOC Dropout Voltage2 ΔVLDO/ LDOA, LDOB, LDOC Line Regulation VLDO*ΔVIN LDOA, LDOB, LDOC Power Supply Rejection Ratio PSRR[A/B/C] LDOA, LDOB, LDOC Auto-Discharge Resistance ROUT_(DCHG) EN/SET AS2Cwire and Logic Control EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input High VIH Threshold Voltage EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input Low VIL Threshold Voltage EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input LeakIIN(LKG) age Current EN/SET Input OFF Timeout tEN/SET(OFF) EN/SET Input Latch Timeout tEN/SET(LAT) EN/SET Input LOW Time tEN/SET(LOW) EN/SET Minimum High Time tENSET(H-MIN) EN/SET Maximum High Time tENSET(H-MAX) 2.7V ≤ VIN ≤ 5.5V 2.7V ≤ VIN ≤ 5.5V EN/SET = IN = 5V 0.3 1. The AAT2861 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. VDO[A/B/C] is defined as VIN – LDO[A/B/C] when LDO[A/B/C] is 98% of nominal. 2861.2009.02.1.2 www.analogictech.com 5 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Typical Characteristics Backlight Efficiency vs. Input Voltage 100 90 100 90 Flash Efficiency vs. Input Voltage Efficiency (%) Efficiency (%) 80 70 60 50 40 30 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 80 70 60 50 40 30 2.7 30mA/ch, VF = 3.95V 15mA/ch, VF = 3.5V 4.2mA/ch, VF = 3.4V 320mA/ch, VF = 3.25V 160mA/ch, VF = 3.15V 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Input Voltage (V) Backlight Current Matching vs. Temperature (VIN = 3.6V; 20mA/ch) Backlight Output Current (mA) 22 21 20 19 Channel 1 - Channel 6/7 18 17 16 -40 Charge Pump Output Turn On Characteristic (VIN = 3.6V; 0mA/ch; COUT = 2.2µF) Output Voltage (bottom) (V) 4.0 VEN/SET (top) (V) 2.0 0.0 4.0 3.0 2.0 1.0 0.0 -15 10 35 60 85 Temperature (°C) Time (50µs/div) Turn On to 1X Mode Flash (VIN = 4.2V; 300mA/ch) VFL_EN (2V/div) VOUT (2V/div) VFLX (2V/div) IIN (200mA/div) Time (50µs/div) 4 2 0 600 400 200 0 4 2 0 Turn On to 1.5X Mode Flash (VIN = 3.6V; 300mA/ch) 4 VFL_EN (2V/div) VOUT (2V/div) VFLX (2V/div) IIN (200mA/div) Time (50µs/div) 4 2 0 2 0 600 400 200 0 6 www.analogictech.com 2861.2009.02.1.2 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Typical Characteristics Turn On to 2X Mode Flash (VIN = 2.8V; 300mA/ch) 4 Turn On to 1X Mode Backlight (VIN = 3.6V; 20mA/ch) VEN/SET (2V/div) 0V VFL_EN (2V/div) VOUT (2V/div) VFLX (2V/div) IIN (200mA/div) Time (50µs/div) 4 2 0 2 0 VOUT (2V/div) 600 400 200 0 VSINK (2V/div) 0V IIN (100mA/div) 0A Time (200µs/div) Turn On to 1.5X Mode Backlight (VIN = 3.2V; 20mA/ch) VEN/SET (2V/div) 0V Turn On to 2X Mode Backlight (VIN = 3.0V; 20mA/ch) VEN/SET (2V/div) 0V VOUT (2V/div) VSINK (2V/div) IIN (200mA/div) 0V VOUT (2V/div) VSINK (2V/div) IIN (200mA/div) Time (200µs/div) 0V 0A 0A Time (200µs/div) Turn Off from 1.5X Mode Backlight (VIN = 3.2V; 20mA/ch) Input Voltage (AC coupled) (top) (mV) Operating Characteristic (VIN = 3.2V; 20mA/ch Backlight; 1.5x Mode; COUT = 2.2µF) Charge Pump Output Voltage (AC coupled) (bottom) (mV) 20 10 0 VEN/SET (2V/div) VDIODE (2V/div) IIN (200mA/div) 50 0 -50 Time (200µs/div) Time (500ns/div) 2861.2009.02.1.2 www.analogictech.com 7 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Typical Characteristics Operating Characteristic LDO Output Voltage Deviatoin (%) (VIN = 3.0V; 20mA/ch Backlight; 2X Mode; COUT = 2.2µF) Charge Pump Output Voltage (AC coupled) (bottom) (mV) Input Voltage (AC coupled) (top) (mV) 20 10 0 20 10 0 -10 -20 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 0.1 1 10 100 1000 LDO A/B/C Load Regulation (VIN = 3.6V) VOUT = 1.8V VOUT = 3.0V Time (500ns/div) Load Current (mA) LDO A/B/C Output Voltage vs. Temperature LDO Output Voltage Deviatoin (%) (VIN = 3.6V; ILDO = 0mA) 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -40 LDO A/B/C Load Transient Response (ILDO = 10mA to 200mA; VIN = 3.6V; VLDO = 1.8V; CLDO = 2.2µF) LDO Output Current (top) (mA) VOUT = 1.8V VOUT = 3.3V 200 100 0 -100 -200 -300 -400 -500 2.00 1.90 1.80 1.70 1.60 LDO Output Voltage (bottom) (V) -15 10 35 60 85 Temperature (°C) Time (20µs/div) LDO A/B/C Line Transient Response (VIN = 3.6V to 4.2V; ILDO = 10mA; VOUT = 1.8V; CLDO = 2.2µF) 4.4 4.0 LDO A/B/C Turn On Characteristic (VLDO = 1.8V; VIN = 3.6V; CLDO = 2.2µF) LDO Output (bottom) (V) LDO Output Voltage (bottom) (V) Input Voltage (top) (V) 4.0 3.6 1.82 1.81 1.80 1.79 1.78 VENLDOX (top) (V) 2.0 0.0 1.5 1.0 0.5 0.0 Time (1ms/div) Time (20µs/div) 8 www.analogictech.com 2861.2009.02.1.2 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Typical Characteristics EN/SET, FL_EN, EN_LDOA, EN_LDOB/C High Threshold Voltage vs. Input Voltage 1.4 EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Low Threshold Voltage vs. Input Voltage 1.2 VEN/SET(H), VFL_EN(H), VEN_LDOA(H), VEN_LDOB/C(H) (V) VEN/SET(L), VFL_EN(L), VEN_LDOA(L), VEN_LDOB/C(L) (V) 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 -40°C 25°C 85°C -40°C 25°C 85°C 0.4 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 0.2 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 Input Voltage (V) Input Voltage (V) EN/SET Input Latch Timeout vs. Input Voltage 400 350 300 250 200 150 100 2.7 EN/SET Input Off Timeout vs. Input Voltage 500 450 400 TOFF (µs) -40°C 25°C 85°C 3.1 3.5 3.9 4.3 4.7 5.1 5.5 TLAT (µs) 350 300 250 200 150 100 2.7 3.1 3.5 3.9 4.3 4.7 -40°C 25°C 85°C 5.1 5.5 Input Voltage (V) Input Voltage (V) 2861.2009.02.1.2 www.analogictech.com 9 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Functional Block Diagrams AAT2861IMK-1-T1 IN IN C1C1+ C2C2+ LDOA 1x/1.5x/2x Tri-mode Charge Pump LDOB OUT 8 LDOC REF BL1 EN/SET FL_EN 5 Main Backlight Current Control BL2 BL3 BL4 EN_LDOA Control Logic 5 BL5 EN_LDOB/C Sub Backlight Current Control BL6 BL7 4 Flash Control FL1 PGND AGND 10 www.analogictech.com 2861.2009.02.1.2 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit AAT2861IMK-2-T1 IN IN C1C1+ C2C2+ LDOA 1x/1.5x/2x Tri-mode Charge Pump LDOB OUT 8 LDOC REF BL1 EN/SET 5 Main Backlight Current Control BL2 BL3 BL4 EN_LDOA Control Logic 5 EN_LDOB/C Sub Backlight Current Control BL5 BL6 FL_EN 4 Flash Control FL2 FL1 PGND AGND 2861.2009.02.1.2 www.analogictech.com 11 PRODUCT DATASHEET AAT2861 AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit AAT2861IMK-3-T1 IN IN C1C1+ C2C2+ LDOA 1x/1.5x/2x Tri-mode Charge Pump LDOB OUT 8 LDOC REF BL1 EN/SET 5 BL2 Main Backlight Current Control BL3 BL4 EN_LDOA Control Logic 5 BL5 FL_EN EN_LDOB/C Sub Backlight Current Control Flash Control BL6 BL7 4 FL1 PGND AGND 12 www.analogictech.com 2861.2009.02.1.2 PRODUCT DATASHEET AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit imately 1mA steps while the flash LED current can be set between 0 and 600mA in 40mA steps or 0 to 300mA in 20mA steps for two channel flash version. The backlight LED currents match to within 3% while the flash LED currents match to within 5%. To eliminate the latency of the AS2Cwire serial interface, the flash LED is enabled through a dedicated input, FL_EN. The AAT2861 also includes a safety timer that prevents thermal overstress of the flash LED(s). This is important because many flash LEDs operate for a brief period beyond their steady-state operating limitations. If the flash driving hardware and/or software fail to turn the LED off, the safety timer insures that the LED or other circuitry is not damaged. Both the backlight and flash LED currents are programmed through the AS2Cwire serial interface as are the backlight fade-in/fade-out timer and the flash safety timer. See the “AS2Cwire Serial Interface Programming” section of this datasheet for more information on setting the LED currents. Functional Description The AAT2861 is a highly integrated backlight and photoflash driver family with three LDO regulators. The charge pump LED driver powers the backlight and flash LEDs from the 2.7V to 5.5V input voltage. The LDO regulators are powered from the same input and produce regulated output voltage between 1.2V and 3.3V. Control of the LEDs and the LDO output voltage is through an AS2Cwire serial interface for easy programming. LED Drivers The AAT2861 drives six or seven backlight LEDs up to 31mA each and a total of 600mA flash current through one or two channels. The LEDs are driven from a charge pump to insure that constant current is maintained over the entire battery voltage range. The charge pump automatically switches from 1X, to 1.5X, to 2X modes and back to maintain the LED current while minimizing power loss for high efficiency. The charge pump operates at the high 1MHz switching frequency, allowing the use of small 1μF ceramic capacitors. Each individual LED is driven by a current sink to GND, allowing individual current control with high accuracy over a wide range of input voltages and LED forward voltages while maintaining high efficiency. The charge pump is controlled by the voltage across the LED current sinks. When any one of the active backlight current sink/channel voltages drops below 200mV or the flash current sink/channel drops below 450mV, the charge pump goes to the next higher mode (from 1X to 1.5X or from 1.5X to 2X mode) to maintain sufficient LED voltage for constant LED current. The AAT2861 continuously monitors the LED forward voltages and uses the input voltage to determine when to reduce the charge pump mode for better efficiency. There is also a 300mV mode-transition hysteresis that prevents the charge pump from oscillating between modes. LDO Regulators The AAT2861 includes three low dropout (LDO) linear regulators. These regulators are powered from the battery and produce a fixed output voltage set through the AS2Cwire serial interface. The output voltage can be set to one of 16 output voltages between 1.2V and 3.3V. The LDO regulators can be turned on/off with the external enable pins EN_LDOA and EN_LDOB/C. Additionally, the AS2Cwire interface allows the LDO regulators to be enabled independently when the EN_LDOA and EN_ LDOB/C pins are pulled high. The LDO regulators require only a small 2.2μF ceramic output capacitor for stability. If improved load transient response is required, larger-valued capacitors can be used without stability degradation. AS2Cwire Serial Interface Protocol The AAT2861 is dynamically programmable by the AS2Cwire single-wire interface. AS2Cwire records rising edges detected at the EN/SET pin to address and load the data registers. The timing diagram in Figure 1 shows the typical transmission protocol. LED Current Control Both the backlight and flash LED currents are controlled through the AS2Cwire serial interface. The backlight LED current can be set between 0.5mA and 31mA in approx- 2861.2009.02.1.2 www.analogictech.com 13 PRODUCT DATASHEET AAT2861 ChargePumpTM Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit Address THI TLO TLAT TLAT Data EN/SET 1 2 17 18 1 2... n