LTC3251/ LTC3251-1.2/LTC3251-1.5 500mA High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converter FEATURES DESCRIPTIO Up to 500mA Output Current The LTC 3251/LTC3251-1.2/LTC3251-1.5 are 2-phase No Inductors charge pump step-down DC/DC converters that produce a 2.7V to 5.5V Input Voltage Range regulated output from a 2.7V to 5.5V input. The parts use 2x Efficiency Improvement Over LDOs switched capacitor fractional conversion to achieve twice 2-Phase, Spread Spectrum Operation the typical efficiency of a linear regulator. No inductors are for Low Input and Output Noise required. V is resistor programmable from 0.9V to 1.6V OUT Shutdown Disconnects Load from V or fixed at 1.2V or 1.5V, with up to 500mA of load current IN Adjustable Output Voltage Range: 0.9V to 1.6V available. Fixed Output Voltages: 1.2V, 1.5V A unique 2-phase spread spectrum architecture provides Super Burst, Burst and Burst Defeat Operating Modes a very low noise regulated output as well as low noise at the Low Operating Current: I = 35A (Burst Mode IN input.* The parts have four operating modes: Continuous Operation) Spread Spectrum, Spread Spectrum with Burst Mode Super Burst Operating Current: I = 10A TM IN operation, Super Burst mode operation and shutdown. Low Shutdown Current: I = 0.01A Typ IN Low operating current (35A in Burst Mode operation, Soft-Start Limits Inrush Current at Turn-On 10A in Super Burst mode operation) and low external Short-Circuit and Overtemperature Protected parts count make the LTC3251/LTC3251-1.2/LTC3251-1.5 Available in a Thermally Enhanced ideally suited for space-constrained battery-powered 10-Pin MSOP Package applications. The parts are short-circuit and overtempera- U ture protected, and are available in a thermally enhanced APPLICATIO S 10-pin MSOP package. Handheld Devices , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Cellular Phones Burst Mode is a registered trademark of Linear Technology Corporation. Super Burst is a trademark of Linear Technology Corporation. Portable Electronic Equipment All other trademarks are the property of their respective owners. Protected by US Patents including 6411531. DSP Power Supplies 1.5V Efficiency vs Input Voltage TYPICAL APPLICATIO (Burst Mode Operation) 100 I = 200mA OUT Spread Spectrum Step-Down Converter 90 LTC3251-1.5 80 OFF ON 70 19 MD0 MD1 60 LTC3251-1.5 50 2 7 V = 1.5V OUT LDO V V 1-CELL Li-Ion IN OUT 500mA 40 3 OR 1F 8 + + 10F C1 C2 3-CELL NiMH 30 1F 1F 4 6 C1 C2 20 5, 11 10 GND MODE 10 3251 TA01 0 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) 3251 TA02 32511215fb 1 EFFICIENCY (%) U ULTC3251/ LTC3251-1.2/LTC3251-1.5 ABSOLUTE AXI U RATI GS (Notes 1, 7) V to GND ................................................... 0.3V to 6V Operating Temperature Range (Note 3) ... 40C to 85C IN MD0, MD1, MODE and FB to GND . 0.3V to (V + 0.3V) Storage Temperature Range .................. 65C to 150C IN I (Note 2) ...................................................... 650mA Lead Temperature (Soldering, 10 sec) ................... 300C OUT UUW PACKAGE/ORDER I FOR ATIO TOP VIEW TOP VIEW ORDER PART ORDER PART MD0 1 10 MODE MD0 1 10 MODE NUMBER NUMBER V 2 9 MD1 V 2 9 MD1 IN IN + + + + C1 3 8 C2 C1 3 11 8 C2 11 LTC3251EMSE-1.2 C1 4 7 V C1 4 7 V OUT OUT LTC3251EMSE GND 5 6 C2 GND 5 6 C2 LTC3251EMSE-1.5 MSE PACKAGE MSE PACKAGE 10-LEAD PLASTIC MSOP 10-LEAD PLASTIC MSOP MSE PART MARKING MSE PART MARKING EXPOSED PAD IS GND (PIN 11), EXPOSED PAD IS GND (PIN 11), LTAGM MUST BE SOLDERED TO PCB MUST BE SOLDERED TO PCB LTB4 T = 125C, = 40C/W, = 10C/W T = 125C, = 40C/W, = 10C/W JMAX JA JC JMAX JA JC LTABE Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: