General Description

The MAX845 provides an isolated power supply small enough to fit in thin PCMCIA cards and space-sensitive applications. It drives a low-profile center-tapped transformer primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated positive or negative voltage at powers up to 750mW.

The MAX845 consists of an oscillator followed by a toggle flip-flop. The flip-flop generates two 50% duty-cycle square waves, which are complementary at half the oscillator frequency (450kHz, min). These two signals drive the ground-referenced N-channel power switch es. Internal circuitry ensures break-before-make action between the two switches.

A low-power shutdown disables both the switches and the oscillator, reducing power consumption. An evaluation kit (MAX845EVKIT-MM) is available to evaluate low profile 5V 40mA and 5V 100mA applications.

Features

♦ Transformer Driver for Ultra-Thin 5V-µs Transformers

♦ Isolated DC-to-DC Power Supply for PCMCIA Applications

♦ 450kHz Minimum Switching Frequency

♦ Ultra-Low Input Supply Current Ripple

♦ Single +5V or +3.3V Supply

♦ 5µW Low-Power Shutdown Mode

♦ 8-Pin SO and µMAX Packages

♦ Low Output Ripple Permits Miniature Output Capacitors

Applications

  PCMCIA Modem Cards

  Isolated Data Acquisition

  Isolated Interface Power Supply

  Noise-Immunity Communications Interface

  Bridging Ground Differences

  Medical Equipment

  Process Control

  Low-Power LAN Networks