Patent ID: 8654548
Filing Date: 2014-02-18
Classification: H02M

Abstract:
1. A primary-side output voltage sensing apparatus for a flyback power converter comprising: a transformer comprising: a switching circuit operatively connected to the primary winding and configured to selectively connect an end of the primary winding to ground; a pulse width modulation (PWM) controller configured to produce a periodic PWM waveform for opening and closing the switching circuit during each cycle of the PWM waveform; a timing circuit including a counter and configured to: a sensing circuit operatively connected to the primary winding and configured to generate the stop pulse by comparing a measurement of a voltage on the primary winding to a threshold voltage; a strobe circuit adapted to generate a voltage-sampling strobe during the (N+1)th PWM cycle based at least in part on the value stored in the counter; a sample and hold circuit operatively connected to the primary winding and the strobe circuit and configured to sample a voltage sample when triggered by the voltage-sampling strobe.