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LTC3240 - 3.3V/2.5V Step-Up/Step-Down Charge Pump DC/DC Converter

With input voltages greater than the regulated output voltage the LTC3240 operates as a low dropout regulator. Once the input voltage drops within 100mV of the regulated output voltage the part automatically switches to step-up mode. In step-up mode the LTC3240 operates as a constant frequency (1.2MHz) doubling charge pump.

The LTC3240-3.3/LTC3240-2.5 feature low no load operating current (65µA typical) and ultralow operating current in shutdown (<1µA). Built-in soft-start circuitry prevents excessive inrush current during start-up. Thermal shutdown and current-limit circuitry allow the parts to survive a continuous short-circuit from VOUT to GND.

The LTC3240-3.3/LTC3240-2.5 require only three tiny external ceramic capacitors for an ultrasmall application footprint. The LTC3240-3.3/LTC3240-2.5 are available in a 6-pin (2mm × 2mm) DFN package.

Features Step-Up/Step-Down Charge Pumps Generate Fixed 3.3V or 2.5V Outputs VIN Range: 1.8V to 5.5V Output Current up to 150mA Automatic Mode Switching Constant Frequency (1.2MHz) Operation in Step-Up Mode Low Dropout Regulator Operation in Step-Down Mode Low No-Load Quiescent Current: IQ = 65µA Built-In Soft-Start Reduces Inrush Current Shutdown Disconnects Load from Input Shutdown Current < 1µA Short-Circuit/Thermal Protection Available in a 6-Lead (2mm × 2mm) DFN Package Typical Application

Applications 2 AA to 2.5V 2-3 AA/Li-Ion to 3.3V Low Power Supplies for Cameras, I/O Supplies, Audio, PC Cards, Misc. Logic, etc., in a Wide Variety of Handheld Products Packaging

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