The UC2577-ADJ device provides all the active functions necessary to implement step-up (boost), flyback, and forward converter switching regulators. Requiring only a few components, these simple regulators efficiently provide up to 60V as a step-up regulator, and even higher voltages as a flyback or forward converter regulator.

The UC2577-ADJ features a wide input voltage range of 3.0V to 40V and an adjustable output voltage. An on-chip 3.0A NPN switch is included with undervoltage lockout, thermal protection circuitry, and current limiting, as well as soft start mode operation to reduce current during startup. Other features include a 52kHz fixed frequency on-chip oscillator with no external components and current mode control for better line and load regulation.

A standard series of inductors and capacitors are available from several manufacturers optimized for use with these regulators and are listed in this data sheet.

• Requires Few External Components
• NPN Output Switches 3.0A, 65V(max)
• Extended Input Voltage Range: 3.0V to 40V
• Current Mode Operation for Improved Transient Response, Line Regulation, and Current Limiting
• Soft Start Function Provides Controlled Startup
• 52kHz Internal Oscillator
• Output Switch Protected by Current Limit, Undervoltage Lockout and Thermal Shutdown
• Improved Replacement for LM2577-ADJ Series
• TYPICAL APPLICATIONS
  • Simple Boost and Flyback Converters
  • SEPIC Topology Permits Input Voltage to be Higher or Lower than Output Voltage
  • Transformer Coupled Forward Regulators
  • Multiple Output Designs