MAX1576 19-3326 Rev 1 8/05 480mA White LED 1x/1.5x/2x Charge Pump for Backlighting and Camera Flash General Description Features The MAX1576 charge pump drives up to 8 white LEDs Powers Up to 8 LEDs with regulated constant current for uniform intensity. Up to 30mA/LED Drive for Backlight The main group of LEDs (LED1LED4) can be driven Up to 400mA Total Drive for Flash up to 30mA per LED for backlighting. The flash group of LEDs (LED5LED8) are independently controlled and 85% Average Efficiency (P / P ) Over Li+ LED BATT can be driven up to 100mA per LED (or 400mA total). Battery Discharge By utilizing adaptive 1x/1.5x/2x charge-pump modes 0.7% Typical LED Current Matching and very-low-dropout current regulators, the MAX1576 achieves high efficiency over the full 1-cell lithium-bat- Adaptive 1x/1.5x/2x Mode Switchover tery voltage range. The 1MHz fixed-frequency switch- Flexible Brightness Control ing allows for tiny external components, and the Single-Wire, Serial Pulse Interface (5% to 100%) regulation scheme is optimized to ensure low EMI and low input ripple. 2-Bit (3 Levels) Logarithmic Logic The MAX1576 uses two external resistors to set the Low Input Ripple and EMI main and flash full-scale (100%) LED currents. Four Low 0.1A Shutdown Current control pins are used for LED dimming by either serial control or 2-bit logic per group. ENM1 and ENM2 set 2.7V to 5.5V Supply Voltage Range the main LEDs to 10%, 30%, or 100% of full scale. Soft-Start Limits Inrush Current ENF1 and ENF2 set the flash LEDs to 20%, 40%, or Output Overvoltage Protection 100% of full scale. In addition, connect either pair of control pins together for single-wire, serial pulse dim- Thermal-Shutdown Protection ming control. 24-Pin Thin QFN, 4mm x 4mm Package The MAX1576 is available in a 24-pin thin QFN, 4mm x 4mm package (0.8mm max height). Ordering Information Applications PART TEMP RANGE PIN-PACKAGE 24 Thin QFN 4mm x Camera Phones MAX1576ETG -40C to +85C 4mm (T2444-4) LCD Backlights 24 Thin QFN 4mm x LED Camera Flashes MAX1576ETG+ -40C to +85C 4mm (T2444-4) Cell Phones and Smart Phones + Denotes lead-free package. PDAs, Digital Cameras, and Camcorders Pin Configuration appears at end of data sheet. Typical Operating Circuit 1F1F INPUT OUTPUT 2.7V TO 5.5V UP TO 480mA C1P C1N C2P C2N INP OUT FLASH MAIN IN 4.7F 4.7F 1F GND1 LED1 LED2 MAX1576Y ENM1 LED3 LED4 ON/OFF AND ENM2 LED5 CURRENT ENF1 LED6 SETTING LED7 ENF2 LED8 SETM SETF GND2 PGND Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLE480mA White LED 1x/1.5x/2x Charge Pump for Backlighting and Camera Flash ABSOLUTE MAXIMUM RATINGS INP, IN, OUT, ENM1, ENM2, ENF1, OUT Short Circuit to GND ..........................................Continuous ENF2 to GND1 .......................................................-0.3V to +6.0V Continuous Power Dissipation (T = +70C) A SETF, SETM, LED1, LED2, LED3, LED4, LED5, 24-Pin Thin QFN (derate 20.8mW/C LED6, LED7, LED8 to GND1 ....................-0.3V to (V + 0.3V) above +70C)..............................................................1666mW IN C1N, C2N to GND1 ........................................-0.3V to (V + 1V) Operating Temperature Range ...........................-40C to +85C IN C1P, C2P to Junction Temperature......................................................+150C GND1................ -0.3V to Greater of (V + 1V) or (V + 1V) Storage Temperature Range .............................-65C to +150C OUT IN GND2, PGND to GND1 .........................................-0.3V to +0.3V Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = 3.6V, V = V = V = 0V, ENM1 = ENM2 = ENF1 = ENF2 = IN, R = R = 6.8k, T = -40C to +85C, IN GND1 GND2 PGND SETM SETF A unless otherwise noted. Typical values are at T = +25C.) (Note 1) A PARAMETER CONDITIONS MIN TYP MAX UNITS IN Operating Voltage 2.7 5.5 V Undervoltage-Lockout Threshold V rising or falling 2.25 2.45 2.60 V IN Undervoltage-Lockout Hysteresis 50 mV Overvoltage Protection Threshold V rising 5 V OUT 1MHz switching, no load, 1.5x or 2x mode 3.8 6.0 Supply Current mA 1x mode 10% setting, LED5LED8 off 0.3 Shutdown Supply Current ENM1 = ENM2 = ENF1 = ENF2 = GND 0.1 3 A Soft-Start Time 2ms SET Bias Voltage 0.604 V SET Leakage in Shutdown ENM1 = ENM2 = ENF1 = ENF2 = GND, V = 0V or V 0.01 1A SET IN SETM Current Range 40 130 A SETF Current Range 40 145 A SETM to Main LED Current Ratio 100% setting, LED14 233 A/A (I / I ) LED SETM SETF to Flash LED Current Ratio 100% setting, LED58 708 A/A (I / I ) LED SETF LED14 -6 +6 LED Current Accuracy % LED58 -8 +8 LED to LED Current Matching (Note 2) -3.5 0.7 +3.5 % LED1LED4, R = 4.64k 27 30 SETM Maximum LED Sink Current mA LED5LED8, R = 4.12k 90 100 SETF LED Dropout Voltage (Note 3) 40 90 mV LED 1.5x and 2x Regulation 150 mV Voltage LED 1x to 1.5x or 1.5x to 2x 90 100 110 mV Mode Transition Threshold Input-Voltage-Mode Transition 150 mV Hysteresis 2 MAX1576