Patent ID: 8199538

Claim:
A switch mode power supply (SMPS) current regulation system, said SMPS including a transformer with at least a primary winding coupled to an input of the SMPS and a secondary winding coupled to an output of the SMPS, the SMPS having a switching device to switch power to said primary winding responsive to a drive signal, the current regulation system comprising: a current sense input to receive a current sense signal sensing a current on said primary winding of said transformer; a voltage sense input to receive a voltage sense signal from said primary winding or an auxiliary winding of said transformer; a drive signal input to receive said drive signal; a timing signal generator coupled to said voltage sense input and to said drive signal input to generate a first timing signal indicating a duration of a period for which current is flowing through said primary winding and a second timing signal indicating a duration of a period for which current is flowing through said secondary winding, wherein one or both of said first timing signal and said second timing signal are generated responsive to said voltage sense signal or said current sense signal; and an output current regulator coupled to said current sense input and to said timing signal generator to provide an output current regulation signal responsive to an average of said current sense signal multiplied by a ratio of said second timing signal to said first timing signal, wherein said timing signal generator is configured to generate at least one edge of said first timing signal from said voltage sense signal or said current sense signal.