Abstract: A regulating control circuit for a single-ended switching power supply includes means for controlling the switching duty cycle during start-up, normal operation and current limiting modes. Normal operation utilizes a duty cycle of less than about 50%, but low input voltage operation can occur for limited times at duty cycles up to 70%-80%. A time base generator defines the maximum permissible switch conduction time, as well as the switching rate. During start-up, input current is restricted to reduce dissipation within the control circuit, the start-up duty cycle also being maintained at a low value by extending the switch non-conduction time. In the current limiting mode, the duty cycle is reduced as a function of current demand to achieve constant current operation over a given range of output voltages, and to achieve current foldback below such range. In current foldback, the switch non-conduction period is extended to obtain unusually low duty cycles in near shorted output conditions.

Abstract: A switching type power supply is described which employs pulse width and rate modulation. Enhanced control range is achieved by controlling a frequency determining circuit to increase operating frequency as a function of power switch pulse width. The power switch controls the switching of primary current in a transformer whose secondary supplies the output via a rectifier/filter circuit.

Abstract: An integrated magnetic assembly for use in the direct current output circuit of a high frequency electronic switching power supply, comprising magnetic core sections for the output transformer and inductor windings and a common magnetic core segment completing the magnetic flux paths for the transformer and inductor windings. An auxiliary winding on one or both of the core sections is supplied with energy from the capacitor of a snubber circuit connected across the primary side of the magnetic output circuit. This auxiliary winding is magnetically coupled to the secondary side of the magnetic circuit to transfer energy to the power supply output during a portion of the switched current cycle.