General Description

The LM2576 series of monolithic integrated circuits provide all the active functions for a step-down (buck) switching regulator. Fixed versions are available with a 3.3V, 5V, or 12V fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are capable of driving a 3A load with excellent line and load regulation.

Features

• 3.3V, 5V, 12V, 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 output current

• Wide input voltage range:

4V to 40V

• Wide output voltage range

1.23V to 37V

• Requires only 4 external components

• 52kHz fixed frequency internal oscillator

• Low power standby mode IQ typically < 200µA

• 80% efficiency (adjustable version typically > 80%)

• Uses readily available standard inductors

• Thermal shutdown and current limit protection

• 100% electrical thermal limit burn-in

Applications

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

• Efficient pre-regulator for linear regulators

• On-card switching regulators

• Positive to negative converter (inverting Buck-Boost)

• Isolated Flyback Converter using minimum number of

external components

• Negative Boost Converter