General Description

The MAX639/MAX640/MAX653 step-down switching regulators provide high efficiency over a wide range of load currents, delivering up to 225mA. A current-limiting pulse-frequency-modulated (PFM) control scheme gives the devices the benefits of pulse-width-modulated (PWM) converters (high efficiency at heavy loads), while using only 10µA of supply current (vs. 2mA to 10mA for PWM converters). The result is high efficiency over a wide range of loads.

Features

♦ High Efficiency for a Wide Range of Load Currents

♦ 10µA Quiescent Current

♦ Output Currents Up to 225mA

♦ Preset or Adjustable Output Voltage:

    5.0V (MAX639)

    3.3V (MAX640)

    3.0V (MAX653)

♦ Low-Battery Detection Comparator

♦ Current-Limiting PFM Control Scheme

Applications

    9V Battery to 5V, 3.3V, or 3V Conversion

    High-Efficiency Linear Regulator Replacement

    Portable Instruments and Handy-Terminals

    5V-to-3.3V Converters