Quick-reset circuit for auxiliary power supply

摘要

Run/standby switching including switching to standby upon excessive current loading are provided in a switched mode power supply useful as an auxiliary power supply in a television. A switching controller IC is coupled between a primary transformer winding on the rectified raw B+ input voltage and ground. A switching transistor is coupled to the control input of the controller and is biased by the raw B+ input voltage for pulling down the control input. A run/standby control circuit and an overcurrent protective circuit disable the switching transistor during run mode operation and enable the switching transistor upon an overcurrent fault. The switched-mode power supply is further provided with a quick-reset capability to enable the power supply to consistently provide output voltages which are within nominal output voltage levels despite rapidly repeated dislocations in the operational mode of the apparatus.