| 摘要 |
A circuit for protecting a motherboard includes a first transistor (Q 1 ), a second transistor (Q 2 ), a third transistor (Q 3 ), and a power control circuit ( 200 ). The power control circuit includes a power controller ( 10 ), and a power supply ( 20 ), and a fourth transistor (Q 4 ) connected therebetween. The first transistor is supplied with a CPU power signal on the motherboard. The second and third transistors are jointly supplied with a sleep signal and turned on if the CPU power signal is at low level after the power supply is turned on, thereby turning off the fourth transistor and grounding a PWRBTN# pin of the power controller to turn off the power supply for protecting the motherboard from damage due to no CPU power-on voltage applied thereto after the power supply is turned on.
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