Power supply start up circuit

摘要

A circuit for providing a secondary output voltage from an input voltage. The circuit comprises power supply circuitry for creating an unregulated DC bus voltage line, a regulator circuit connected to the DC bus voltage line for controlling a first switch in series with a transformer winding, the control circuit sampling an output voltage to control the output voltage by cycling the switch, a pulse generator circuit connected to the regulator circuit for controlling start and stop cycles of the regulator circuit, and a comparator circuit connected to the pulse generator circuit, for monitoring the secondary output voltage and disabling the pulse generator circuit during normal operation of the power supply circuit.