New offline switching regulators achieve ±1% regulation in a flux sensed converter

A novel IC that addresses the problems in using flux sensing for output regulation in offline power supplies is described. The LT1103/LT1105 offline switching regulators eliminate the need for an opto isolator while providing ±1% line and load regulation in a magnetic flux-sensed power converter. Flux-sensing made practical simplifies the design of universal offline power supplies and provides greater safety and reliability as only the transformer requires IEC 950 conformance. Special circuitry built into the LT1103/LT1105 addresses the problems of primary leakage inductance spikes, nonlinear transformer behavior, and parasitic impedances which are present in a transformer coupled design and which previous control schemes have failed to address. Therefore, the LT1103/LT1105 provides a technological advantage for the user who needs well-registered DC output voltages from the AC line