General Description

The MAX8847Y/MAX8847Z negative charge pumps drive up to 6 white LEDs with regulated constant current for display backlight applications. By utilizing an inverting charge pump and extremely low-dropout adaptive current regulators, these ICs achieve very high efficiency over the full 1-cell Li+ battery voltage range even with large LED forward voltage mismatch. The 1MHz fixed-frequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. The MAX8847Y/MAX8847Z include thermal shutdown, open- and short-circuit protection.

Features

♦ Negative 1x/1.5x Charge Pump

♦ Adaptive Current Regulators

♦ Independent Voltage Supply for Each LED

♦ 24mA to 0.1mA Serial-Pulse Dimming (MAX8847Y)

♦ 24mA to 0mA PWM Dimming (MAX8847Z)

♦ 2 (max) LED Current Accuracy, 1 (typ) Matching

♦ Low 120µA Quiescent Current

♦ Low 0.4µA Shutdown Current

♦ Inrush Current Limit

♦ Temperature Derating Function

♦ 16-Pin, 3mm x 3mm Thin QFN Packages

Applications

   White LED Backlighting

   Cellular Phones

   PDAs, Digital Cameras, and Camcorders