Switched-mode power supply circuit including a power switch.

摘要

A switched-mode power supply circuit for converting a d.c. input voltage into a d.c. output voltage. The circuit includes a controllable power switch (Tr1) arranged in series with the primary winding (L1) of a transformer (T), which winding forms part of a resonant circuit. To reduce the losses caused by turning on of the switch the drive path of the switch incorporates a delay network (R11, C9) for each time delaying this turn-on until an instant which is substantially half a cycle of the resonance frequency later than the initial instant of the decrease of the voltage across the switch during its previous cut-off time.