700mA Low Noise High Current LED Charge Pump

The LTC3215 is a low noise, high current charge pump DC/DC converter designed to power high current LEDs. The part includes an accurate programmable current source capable of driving loads up to 700mA from a 2.9V to 4.4V input. Low external parts count (two flying capacitors, one programming resistor and two bypass capacitors) makes the LTC3215 ideally suited for small, battery powered applications.

Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. LED current is programmed with an external resistor. The LED is disconnected from VIN during shutdown.

An ultralow dropout current source maintains accurate LED current at very low ILED voltages. Automatic mode switching optimizes efficiency by monitoring the voltage across the LED current source and switching modes only when ILED dropout is detected. The LTC3215 is available in a low profile 3mm × 3mm 10-Lead DFN package.

Applications

* LED Torch/Camera Light Supply for Cell Phones, PDAs and Digital Cameras

* General Lighting and/or Flash/Strobe Applications

* High Efficiency Operation: 1x, 1.5x or 2x Boost Modes with Automatic Mode Switching

* Ultralow Dropout ILED Current Control

* Output Current up to 700mA

* Low Noise Constant Frequency Operation*

* Wide VIN Range: 2.9V to 4.4V

* Open/Shorted LED Protection

* LED Disconnect in Shutdown

* Low Shutdown Current: 2.5µA

* 4% LED Current Programming Accuracy

* Automatic Soft-Start Limits Inrush Current

* No Inductors

* Tiny Application Circuit (All Components <1mm Profile)

* 3mm × 3mm 10-Lead DFN Package