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