LM2585 SIMPLE SWITCHER 3A Flyback Regulator

General Description
The LM2585 series of regulators are monolithic integrated circuits specifically designed for flyback, step-up (boost), and forward converter applications. The device is available in 4 different output voltage versions: 3.3V, 5.0V, 12V, and adjustable.
Requiring a minimum number of external components, these regulators are cost effective, and simple to use. Included in the datasheet are typical circuits of boost and flyback regulators. Also listed are selector guides for diodes and capacitors and a family of standard inductors and flyback transformers designed to work with these switching regulators.
The power switch is a 3.0A NPN device that can stand-off 65V. Protecting the power switch are current and thermal limiting circuits, and an undervoltage lockout circuit. This IC contains a 100 kHz fixed-frequency internal oscillator that permits the use of small magnetics. Other features include soft start mode to reduce in-rush current during start up, current mode control for improved rejection of input voltage and output load transients and cycle-by-cycle current limiting.
An output voltage tolerance of g4%, within specified input voltages and output load conditions, is guaranteed for the power supply system.

Features
- Requires few external components
- Family of standard inductors and transformers
- NPN output switches 3.0A, can stand off 65V
- Wide input voltage range: 4V to 40V
- Current-mode operation for improved transient response, line regulation, and current limit
- 100 kHz switching frequency
- Internal soft-start function reduces in-rush current during start-up
- Output transistor protected by current limit, under voltage lockout, and thermal shutdown
- System Output Voltage Tolerance of g4% max over line and load conditions

Typical Applications
- Flyback regulator
- Multiple-output regulator
- Simple boost regulator
- Forward converter