Abstract: An isolated primary circuit regulator is applied to a primary side of a transformer of a power supply. The isolated primary circuit regulator outputs a switching signal, and switches the transformer by using the switching signal, thereby stabilizing an output current. The isolated primary circuit regulator includes a discharge time detector, an oscillator, a pulse width modulator and a control circuit. The discharge time detector is used for detecting a discharge time of a switching current generated at a secondary side of the transformer. The oscillator is used for generating an oscillation signal. The control circuit is used for outputting an adjustment signal. The pulse width modulator outputs a switching signal according to the oscillation signal output by the oscillator and the adjustment signal output by the control circuit. The switching signal has a duty cycle and a frequency corresponding to the oscillation signal and the adjustment signal.

Abstract: An isolated primary circuit regulator is applied to a primary side of a transformer of a power supply. The isolated primary circuit regulator outputs a switching signal, and switches the transformer by using the switching signal, thereby stabilizing an output current. The isolated primary circuit regulator includes a discharge time detector, an oscillator, a pulse width modulator and a control circuit. The discharge time detector is used for detecting a discharge time of a switching current generated at a secondary side of the transformer. The oscillator is used for generating an oscillation signal. The control circuit is used for outputting an adjustment signal. The pulse width modulator outputs a switching signal according to the oscillation signal output by the oscillator and the adjustment signal output by the control circuit. The switching signal has a duty cycle and a frequency corresponding to the oscillation signal and the adjustment signal.