General Description

The MAX8645X/MAX8645Y charge pumps drive up to eight white LEDs with regulated constant current for uniform intensity. The main group of LEDs (M1–M6) can be driven up to 30mA per LED for backlighting. The flash group of LEDs (F1 and F2) is independently controlled and can be driven up to 200mA per LED (or 400mA total). Two 200mA LDOs are on-board to provide power for camera functions. The LDOs’ output voltages are pin programmable to meet different camera-module requirements. The MAX8645X and MAX8645Y differ only in LDO output voltages. By utilizing adaptive 1x/1.5x/2x charge pump modes and very-low-dropout current regulators, the MAX8645X/MAX8645Y achieve high efficiency over the full 1-cell lithium-battery voltage range. The 1MHz fixed-frequency switching allows for tiny external components, and the regulation scheme is optimized to ensure low EMI and low input ripple.

The MAX8645X/MAX8645Y are available in a 28-pin TQFN, 4mm x 4mm (0.8mm max height) lead-free package.

Features

♦ Power Up to Eight LEDs

   Up to 30mA/LED Drive for Backlight

   Up to 400mA Total Drive for Flash

♦ Two Internal Low-Noise 200mA LDOs

♦ 94 Max/85 Avg Efficiency (PLED/PBATT) over Li+

   Battery Discharge

♦ 0.2 Typical LED Current Matching

♦ Adaptive 1x/1.5x/2x Mode Switchover

♦ Single-Wire, Serial-Pulse Interface for Brightness

   Control (32 Steps)

♦ Thermal TA Derating Function

♦ Low Input Ripple and EMI

♦ 2.7V to 5.5V Supply Voltage Range

♦ Soft-Start, Overvoltage, and Thermal-Shutdown

   Protection

♦ 28-Pin TQFN, 4mm x 4mm Package

Applications

   Camera Phones and Smartphones

   Backlighting and Flash

   PDAs, Digital Cameras, and Camcorders