Push-pull power converter with crowbar circuit for very fast output voltage turn-off

A power supply circuit, comprising:

• a converter having an input converter stage comprising four switching devices and associated anti-parallel diodes in a full-bridge configuration coupled to a primary winding of an isolation transformer, the isolation transformer comprising a secondary winding for coupling the input converter stage to an output converter stage, the output stage comprising an output capacitor and a crowbar circuit, the crowbar circuit comprising a trigger device, the crowbar circuit being connected between the transformer secondary winding and the output capacitor such that the voltage across the crowbar circuit comprises the superposition of the voltage across the output capacitor and the voltage across the secondary winding of the transformer;
• and
• a control for operating the converter as a forward converter in an output voltage-on mode, and for creating a reverse voltage pulse on the transformer to activate the trigger device for operation in an output voltage-off mode such that the output capacitor discharges through the crowbar circuit, the anti-parallel diodes of the switching devices providing a current path such that the transformer core is reset after each input voltage pulse.