GENERAL DESCRIPTION  

The LM2576 series of regulators are monolithic  integrated circuits that provide all the active functions for a  step-down (buck) switching regulator, capable of driving 3A  load with excellent line and load regulation. These devices are  available in fixed output voltages of 3.3V, 5V, 12V, 15V and  adjustable output versions. 

Requiring a minimum number of external components,  these regulators are simple to use and include internal  frequency compensation and a fixed-frequency oscillator. 

The LM2576 series offers a high-efficiency replacement  for popular three-terminal linear regulators. It substantially  reduces the size of the heat sink, and in some cases no heat  sink is required. 

A standard series of inductors optimized for use with the  LM2576 series is available from several different manufacturers.  This feature greatly simplifies the design of switch-mode  power supplies. 

Other features include a guaranteed 4% tolerance on the  output voltage within specified input voltages and output load  conditions, and 10% tolerance on the oscillator frequency. An  external shutdown is included, featuring 50A (typical)  standby current. The output switch includes cycle-by-cycle  current limiting, as well as a thermal shutdown for full  protection under fault conditions. 

FEATURES

 3.3V, 5V, 12V, 15V and adjustable output versions 

 Adjustable version output voltage range, 1.23V to 37V  3% max over line and load  conditions 

 Guaranteed 3A output current 

 Wide input voltage range, 40V 

 Requires only 4 external components 

 52 kHz fixed frequency oscillator  

 TTL shutdown capability, low power standby mode  

 High efficiency 

 Uses readily available standard inductors 

 Thermal shutdown and current limit protection 

APPLICATIONS 

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

 Efficient pre-regulator for linear regulators 

 On-card switching regulators 

 Positive to negative converter (Buck-Boost)