General Description

The MAX1574 charge pump drives up to three white LEDs with regulated constant current for uniform intensity. By utilizing adaptive 1x/2x charge-pump modes and very-low-dropout current regulators, it achieves 180mA output drive capability and high efficiency over the 1-cell lithium-battery input voltage range. Fixed-frequency (1MHz) switching allows for tiny external components, and the regulation scheme is optimized to ensure low EMI and low input ripple.

Features

♦ Up to 180mA (60mA/LED) Drive Capability

♦ 83 Average Efficiency (PLED / PBATT) Over Li+ Battery Discharge

♦ 0.5 (typ) LED Current Matching

♦ Adaptive 1x/2x Mode Switchover

♦ Low Input Ripple and EMI

♦ 5 to 100 Dimming Through Single-Wire Serial Pulse Interface

♦ Low 0.1µA Shutdown Current

♦ 2.7V to 5.5V Supply Voltage Range

♦ Soft-Start Limits Inrush Current

♦ Output Overvoltage Protection

♦ Thermal-Shutdown Protection

♦ 10-Pin 3mm x 3mm TDFN Package

Applications

LCD Backlighting

Camera Strobes/Flashes and Movie Lights

Cell Phones/Smart Phones

PDAs, Digital Cameras, and Camcorders