MAX746

High-Efficiency, PWM, Step-Down, N-Channel DC-DC Controller

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Overview

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

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 MAX746's 4V to 15V input voltage range, fixed 5V/adjustable (Dual-Mode™) 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-Mode™) 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.

External components are protected by the MAX746's cycle-by-cycle current limit. The MAX746 also features a 2V ±1.5% reference, a comparator for low-battery detection or level translating, and soft-start and shutdown capability.

The MAX747-discussed in a separate data sheet-functions similarly to the MAX746, but drives P-channel logic level FETs.

Applications