Patent ID: 8261105

Claim:
A switching power circuit connected to a motherboard of a computer system, comprising: a pulse width modulation (PWM) circuit including a phase terminal, wherein the PWM circuit outputs an output voltage to the motherboard via the phase terminal, the PWM circuit further comprising: a first MOS; and a second MOS, wherein a drain of the first MOS is connected to a power voltage, a source of the second MOS is connected to the ground terminal, a source of the first MOS and a drain of the second MOS are connected to the phase terminal, and the value of the output voltage outputted by the phase terminal is controlled by the length of conducting time or blocking time of the first MOS and the second MOS; and a snubber circuit including a zener diode, wherein a negative terminal of the zener diode is connected to the phase terminal, a positive terminal is connected to a ground terminal, and the level of the breakdown voltage of the zener diode is equal to the level of output voltage in a steady state.