| 摘要 |
A pulse width modulation device with a power saving mode controlled by an output voltage feedback hysteresis circuit is used in a power supply. The present invention comprises a hysteresis comparison circuit extracting a feedback voltage, a high threshold voltage and a low threshold voltage, and the voltages are executed by a comparison and hysteresis operation to a output blanking signal, a PWM control unit extracting a detecting current signal and the feedback voltage to output a modulation signal after a comparison operation is executed; an OR gate circuit connected to the hysteresis comparison circuit and the PWM control unit for receiving the blanking signal and the modulation signal to output a reset signal; and a synchronization signal output unit connected to the OR gate circuit for receiving the reset signal and an oscillation signal to output the drive signal.
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