Wednesday, February 19, 2014

LM2577 SIMPLE SWITCHER® Step-Up Voltage Regulator

The LM2577 are monolithic integrated circuits that provide all of the power and control functions for step-up (boost), flyback, and forward converter switching regulators. The device is available in three different output voltage versions: 12V, 15V, and adjustable. Requiring a minimum number of external components, these regulators are cost effective, and simple to use. Listed in this data sheet are a family of standard inductors and flyback transformers designed to work with these switching regulators.

Included on the chip is a 3.0A NPN switch and its associated protection circuitry, consisting of current and thermal limiting, and undervoltage lockout. Other features include a 52 kHz fixed-frequency oscillator that requires no external components, a soft start mode to reduce in-rush current during start-up, and current mode control for improved rejection of input voltage and output load transients.

• Requires Few External Components
• NPN Output Switches 3.0A, can Stand off 65V
• Wide Input Voltage Range: 3.5V to 40V
• Current-mode Operation for Improved Transient Response, Line Regulation,and Current Limit
• 52 kHz Internal Oscillator
• Soft-start Function Reduces In-rush Current During Start-up
• Output Switch Protected by Current Limit, Under-voltage Lockout, and Thermal Shutdown

• Simple Boost Regulator
• Flyback and Forward Regulators
• Multiple-output Regulator