Switched-mode power supply having a circuit arrangement for turning the switching device when a voltage on the switching device is at a minimum

摘要

A circuit arrangement for use in a controller circuit of a switched mode power supply for turning on a power device in the switched- mode power supply when a voltage across the power device is at a minimum. The circuit arrangement includes circuitry for detecting when a change in the voltage across the power device is substantially zero, and for detecting when the voltage across the power device is less than a predetermined level. When these two criteria are met, the circuit arrangement generates a turn-on signal for the power device.