LTC3218

LTC3218 400mA Single Wire Camera LED Charge Pump FEATURES ■ Low Noise Constant-Frequency Operation ■ Multi-Mode Operation: 1x or 2x Boost Mode ■ Automatic Mode Switching ■ High Output Current: 150mA (Continuous), 400mA (Pulsed) From Li-Ion/Polymer Input ■ 2-Second Flash Current Timeout for LED Protection ■ Automatic Soft-Start ■ Output Disconnect ■ No Inductors ■ 220mΩ Internal High Side Current Sense Resistor ■ Single Resistor Programming Capability ■ Tiny Application Circuit (3mm × 2mm DFN Package, All Components < 1mm High) APPLICATIONS ■ LED Torch/Flash Supply for DSCs/Cellphones DESCRIPTION The LTC®3218 is a low-noise, high-current charge pump DC/DC converter capable of driving high current LEDs at up to 400mA from a 2.9V to 4.5V input. A low external parts count (one flying capacitor, two programming resistors and two bypass capacitors at VIN and CPO) make the LTC3218 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. A built-in 2-second timer protects the LED during flash mode. Output current level is programmed by an external resistor. LED current is regulated using an internal high side 220mΩ sense resistor. Automatic mode switching optimizes efficiency by monitoring the voltage across the charge pump and switching modes only when dropout is detected. The part is available in a low profile 3mm × 2mm 10-lead DFN pac...