Patent ID: 7944722

Claim:
A system for sensing an output voltage of a switch mode power supply (SMPS), the SMPS including a switched magnetic energy storage device for conveying power from an input to an output of said SMPS, said magnetic device having at least one winding, the system comprising; a sense input to receive a sensing signal from said at least one winding of said magnetic device, said sensing signal having a waveform with a first, decaying portion during which power is supplied by said magnetic device to said SMPS output and a second, portion during which substantially no power is supplied by said magnetic device to said SMPS output; a signal follower coupled to said sense input to generate a decay signal approximating said decaying portion of said sensing signal waveform; a comparator to compare said decay signal with said sensing signal waveform to identify when said sensing signal waveform decays faster than said decay signal; and a sampler to sample said sensing signal responsive to said comparator to provide an output signal sensing said output voltage of said SMPS.