General Description

The MIC4576 is a series of easy to use fixed and adjustable BiCMOS step-down (buck) switch-mode voltage regulators. The 200kHz MIC4576 duplicates the pinout and function of the 52kHz LM2576. The higher switching frequency may allow up to a 2:1 reduction in output filter inductor size.

The MIC4576 is available in 3.3V, and 5V fixed output versions or a 1.23V to 33V adjustable output version. Both versions are capable of driving a 3A load with excellent line and load regulation.

The feedback voltage is guaranteed to ±2 tolerance for adjustable versions, and the output voltage is guaranteed to ±3 for fixed versions, within specified voltages and load conditions. The oscillator frequency is guaranteed to ±10.

In shutdown mode, the regulator draws less than 200µA standby current. The regulator performs cycle-by-cycle current limiting and thermal shutdown for protection under fault conditions.

This series of simple switch-mode regulators requires a minimum number of external components and can operate using a standard series of inductors. Frequency compensation is provided internally.

The MIC4576 is available in TO-220 (T) and TO-263 (U) packages for the industrial temperature range.

Features

• Fixed 200kHz operation

• 3.3V, 5V, and adjustable output versions

• Voltage over specified line and load conditions:

Fixed version: ±3 max. output voltage

Adjustable version: ±2 max. feedback voltage

• Guaranteed 3A switch current

• Wide 4V to 36V input voltage range

• Wide 1.23V to 33V output voltage range

• Requires minimum external components

• < 200µA typical shutdown mode

• 75 efficiency (adjustable version > 75 typical)

• Standard inductors are 25 of typical LM2576 values

• Thermal shutdown

• Overcurrent protection

• 100 electrical thermal limit burn-in

Applications

• Simple high-efficiency step-down (buck) regulator

• Efficient preregulator for linear regulators

• On-card switching regulators

• Positive-to-negative converter (inverting buck-boost)

• Battery Charger

• Negative boost converter

• Step-down to 3.3V for Intel Pentium™

and similar microprocessors