MAX1575 19-3097 Rev 2 8/05 White LED 1x/1.5x Charge Pump for Main and Sub-Displays General Description Features The MAX1575 charge pump drives up to four white Powers Main and Sub-Display LEDs LEDs in the main display and up to two white LEDs in 85% Average Efficiency (P / P ) Over Li+ LED BATT the sub-display with regulated constant current for uni- Battery Discharge form intensity. By utilizing adaptive 1x/1.5x charge- pump modes and very-low-dropout current regulators, 2% LED Current Matching it achieves high efficiency over the full 1-cell lithium- Up to 30mA/LED Drive Capability battery input voltage range. A 1MHz fixed-frequency Adaptive 1x/1.5x Mode Switchover switching allows for tiny external components, and the regulation scheme is optimized to ensure low EMI and Low Input Ripple and EMI low input ripple. Individual 5% to 100% Dimming Through The MAX1575 uses an external resistor to set the full- Single-Wire Serial Pulse Interface scale 100% LED current. Two enable inputs, ENM and Low 0.1A Shutdown Current ENS, are used for simple on/off controls for the main and sub-displays, respectively. By repeatedly pulsing either 2.7V to 5.5V Supply Voltage Range enable input, the LEDs can be dimmed in multiple steps Soft-Start Limits Inrush Current down to 5%. Once the desired brightness is set, the MAX1575 maintains that brightness setting as long as Output-Overvoltage Protection the enable input is kept high. If an enable input is kept Thermal-Shutdown Protection low for more than 2ms, the LED current for the respec- tive display is set to zero. If both enable inputs are kept 16-Pin Thin QFN 4mm x 4mm Package low for more than 2ms, the MAX1575 enters shutdown. Ordering Information The MAX1575 is available in a 16-pin 4mm x 4mm thin QFN package (0.8mm max height). PART TEMP RANGE PIN-PACKAGE MAX1575ETE -40C to +85C 16 Thin QFN 4mm x 4mm MAX1575ETE+ -40C to +85C 16 Thin QFN 4mm x 4mm Applications + Denotes lead-free package. Cell Phones with Main and Sub-Displays Typical Operating Circuit PDAs/Smart Phones with Up to Six White LEDs 1F Pin Configuration C1P C1N TOP VIEW 2.7V TO 5.5V IN OUT 1F 1F 12 11 10 9 MAX1575 GND MAIN C1N 13 8 LED4 LED1 IN 14 LED5 7 ENABLE MAIN LED2 MAX1575 ON/OFF ENM C2N 15 6 LED6 AND DIMMING LED3 C1P 16 5 ENM + ENABLE SUB LED4 ON/OFF ENS 1 2 3 4 SUB AND DIMMING LED5 SET LED6 THIN QFN R SET C2P C2N 4mm x 4mm 1F 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 AVAILABLE GND C2P OUT LED1 SET LED2 LED3 ENSWhite LED 1x/1.5x Charge Pump for Main and Sub-Displays ABSOLUTE MAXIMUM RATINGS IN, OUT, ENM, ENS to GND..................................-0.3V to +6.0V Continuous Power Dissipation (T = +70C) A SET, LED , C1N, C2N to GND.....................-0.3V to (V + 0.3V) 16-Pin Thin QFN 4mm x 4mm IN C1P, C2P to GND.............................................................-0.3V to (derate 16.9 mW/C above +70C)............................1349mW the greater of (V + 1V) or (V + 1V) Junction Temperature......................................................+150C OUT IN OUT Short Circuit to GND ..........................................Continuous Storage Temperature Range .............................-65C to +150C 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 = 0V, ENM = ENS = IN, R = 6.81k, C = C1 = C2 = C = 1F, T = -40C to +85C, unless otherwise IN GND SET IN OUT A 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 falling 2.25 2.45 2.60 V IN Undervoltage-Lockout Hysteresis 35 mV OUT Overvoltage-Protection Threshold V rising 5 V OUT 1MHz switching in 1.5x mode 2 No-Load Supply Current mA No switching in 1x mode,10% setting 0.5 Shutdown Supply Current ENM = ENS = OUT = GND 0.1 2 A Soft-Start Time 2ms SET Bias Voltage 0.6 V SET Leakage in Shutdown ENM = ENS = GND 0.01 1A T = 0C to +85C10 130 A SET Current Range A T = -40C to +85C30 130 A SET-to-LED Current Ratio (I / I ) 100% setting 234 A/A LED SET T = +25C to +85C-8 2+8 A LED Current Accuracy % T = -40C to +85C -9.5 +9.5 A T = +25C to +85C-5 1.5 +5 A LED-to-LED Current Matching (Note 2) % T = -40C to +85C -6.5 +6.5 A Maximum LED Sink Current R = 4.53k 27.4 30.0 mA SET LED Dropout Voltage (Note 3) 60 100 mV LED 1x-to-1.5x Transition Threshold V falling 90 100 110 mV LED LED Leakage in Shutdown ENM = ENS = GND, V = 5.5V 0.01 1A LED Maximum OUT Current V 3.4V, V = 3.9V, 100% setting 120 mA IN OUT 1x mode (V - V ) / I 1 2.5 IN OUT OUT Open-Loop OUT Resistance 1.5x mode (1.5 x V - V ) / I 4.2 10 IN OUT OUT Switching Frequency 1 MHz OUT Pulldown Resistance ENM = ENS = GND 5 k ENM, ENS High Voltage V = 2.7V to 5.5V 1.6 V IN ENM, ENS Low Voltage V = 2.7V to 5.5V 0.4 V IN ENM, ENS Input Current V = 0V or 5.5V 0.01 1A EN Shutdown Delay From falling edge of ENM and ENS 1.0 2 3.3 ms 2 MAX1575