Features

• Obsolete - Datasheet  For Information Purposes Only.  Contact Linear Technology for Potential Replacement
• ±1% Line and Load Regulation with No Optocoupler
• Switch Frequency Up to 200kHz
• Internal 2A Switch and Current Sense (LT1103)
• 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

Typical Application

Description

Obsolete - Datasheet For Information Purposes Only.  Contact Linear Technology for Potential Replacement

The LT1103 Offline Switching Regulator is designed for high input voltage applications using an external FET switch whose source is driven by the open collect or output of the LT1103. The LT1103 is optimized for 15W to 100W applications. For higher power applications or additional switch current flexibility, the LT1105 is available and its totem pole output drives the gate of an external FET. Unique design of the LT1103/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 LT1103/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. Low external part count for a typical application combines with a