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