| 摘要 |
A power switching means for connecting a power source to a digital data processing system. The switching means includes a power switch for connecting the power source to the system and two control switches. A first control switch determines whether system power is to be turned on or off and is responsive to a turn-on selection signal to provide an initial turn-on signal to the power switch if a power turn-on is to be performed. The second control switch is responsive to a power turn-on/turn-off initialization signal to initiate and control the turn-on and turn-off operations. The second control switch is responsive to the initialization signals at power turn-on to enable the first control switch to be responsive to a power-on selection signal to provide the initial turn-on signal to the power switch. The second control switch thereafter provides a sustaining signal to the power switch during the period in which power is to be provided to the system and is responsive a subsequent initialization signal to terminate the sustaining signal to the power switch, thereby turning off system power. The power switching means further includes a current limiter connected between the power source and the system to limit inrush current during power turn-on and the second switch further includes a bypass switch for providing a low resistance path around the current limiting means during system power on state.
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