General Description

The MAX746 is a high-efficiency, high-current, step-down DC-DC power-supply controller that drives external N-channel FETs. It provides 93 to 96 efficiency from a 6V supply voltage with load currents ranging from 50mA up to 3A. It uses a pulse-width-modulating (PWM) current-mode control scheme to provide precise output regulation and low output noise. The MAX746s 4V to 15V input voltage range, fixed 5V/adjustable (Dual-ModeTM) output, and adjustable current limit make this device ideal for a wide range of applications.

High efficiency is maintained with light loads due to a proprietary automatic pulse-skipping control (Idle-ModeTM) scheme that minimizes switching losses by reducing the switching frequency at light loads. The low 950µA quiescent current and ultra-low 1.4µA shutdown current further extend battery life.

Features

♦ 93 to 96 Efficiency for 50mA to 3A

   Output Currents

♦ 4V to 15V Input Voltage Range

♦ Low 950µA Supply Current

♦ 1.4µA Shutdown Current

♦ Drives External N-Channel FETs

♦ Fixed-Frequency Current-Mode PWM (Heavy Loads)

♦ Idle-Mode PFM (Light Loads)

♦ Cycle-by-Cycle Current Limiting

♦ 2V ±1.5 Accurate Reference Output

♦ Adjustable Soft-Start

♦ Undervoltage Lockout

♦ Precision Comparator for Power-Fail or

   Low-Battery Warning

Applications

   5V-to-3.3V Green PC Applications

   Notebook/Laptop Computers

   Personal Digital Assistants

   Battery-Operated Equipment

   Cellular Phones