Multi-Output Flyback Converter for Metering Applications that Protects Against Magnetic Interference

Multi-output flyback designs address numerous low-power applications. Integrated devices allow for ease of design while also improving protection. A wide input range, acceptable output regulation, and low no-load input power are common requirements. For metering, there is also a need for equipment to withstand external tampering. A design method for reducing the susceptibility of the power stage to externally applied magnetic inter-ference is discussed. Appropriate transformer design, component selection, and leveraging the benefits of ON/OFF control help achieve this. Results show start-up waveforms and thermal data. Efficiency, and no-load input power with and without the imposition of strong external magnetic disturbances are compared.