Importance

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Abstract

A power supply includes a coupled inductor having a primary winding, a secondary winding and a feedback winding. A rectifier/filter is coupled to the secondary winding for supplying the load with a DC current. A power switch is coupled in series with the primary winding for switching between conductive and non-conductive states to control the flow of current through the primary winding. A first drive circuit applies a first drive signal to the control lead of the power switch for switching the power switch into the conductive state. A primary current sense circuit generates a primary current feedback signal representative of the primary winding current. An output current sense circuit generates an output current feedback signal representative of the power supply output current. A programmable reference voltage generator generates a DC reference voltage having a magnitude determined by the output current feedback signal. A power switch control circuit compares the primary current feedback signal with the DC reference voltage and removes the first drive signal from the power switch control lead when the primary current feedback signals reaches a predetermined level to switch the power switch into the non-conductive state. A second drive circuit applies a second drive signal to the control lead of the power switch to maintain the power switch in the non-conductive state while energy is being transferred into the rectifier/filter.

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First Claim