Patent ID: 7248487

Claim:
A switch mode power supply (SMPS) controller for regulating the output of a discontinuous conduction mode (DCM) SMPS in response to a feedback signal from a winding of a magnetic energy storage device forming part of an output circuit of said SMPS, said feedback signal having an oscillatory portion when substantially no energy is being transferred to said SMPS output, the SMPS controller comprising: a reference level input to receive an output voltage reference level signal; a feedback signal input to receive said feedback signal, said feedback signal being responsive to a voltage on said winding; a first comparator coupled to said reference level input and to said feedback signal input and having an output responsive to a comparison of said reference level signal and said feedback signal; a timing signal generator coupled to said feedback signal input to identify a point in said oscillatory portion of said feedback signal and to provide a timing signal responsive to said identification; an integrator coupled to said feedback signal input and to said first comparator output and configured to start integration responsive to said comparison of said reference level signal and said feedback signal, to provide an integrated feedback signal output; a second comparator to compare said integrated feedback signal output at said time identified by said timing signal generator timing signal with a second reference value, and having an output to provide an error signal responsive to said comparison; and a controller output coupled to said second comparator output to provide a control signal for regulating said SMPS output responsive to said error signal.