General Description

The LM2575 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, 12V, fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are capable of driving a 1A load with excellent line and load regulation.These regulators are simple to use because they require a minimum number of external components and include internal frequency compensation and a fixed-frequency oscillator. The LM2575 series offers a high efficiency replacement for popular three-terminal adjustable linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required. A standard series of inductors available from several different manufacturers are ideal for use with the LM2575 series. This

feature greatly simplifies the design of switch-mode power supplies.

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 1A 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