Catalog
Offline Switching Regulator
Key Features
• ±1% Line and Load Regulation with No Optocoupler
• Switch Frequency Up to 200kHz
• Internal 1A Totem-Pole Driver (LT1105)
• Start-Up Mode Draws Only 200µA
• Fully Protected Against Overloads
• Overvoltage Lockout of Main Supply
• Protected Against Underdrive or Overdrive to FET
• Operates in Continuous or Discontinuous Mode
• Ideal for Flyback and Forward Topologies
• Isolated Flyback Mode Has Fully Floating Outputs
Description
AI
The LT1105 Offline Switching Regulator is designed for high input voltage applications using an external FET switch. The LT1105 is available and its totem pole output drives the gate of an external FET. Unique design of the LT1105 eliminates the need for an optocoupler while still providing ±1% load and line regulation in a magnetic flux-sensed converter. This significantly simplifies the design of offline power supplies and reduces the number of components which must cross the isolation barrier to one, the transformer.The LT1105 current mode switching techniques are well suited to transformer isolated flyback and forward topologies while providing ease of frequency compensation with a minimum of external components.APPLICATIONSUp to 250W Isolated Mains ConverterUp to 50W Isolated Telecom ConverterFully Isolated Multiple OutputsDistributed Power Conversion Networks
