Power control circuit with power-off time delay control for microprocessor-based system
AssigneeMitac International Corp.
InventorShi-Fa Hsu
Life of this patent
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Abstract
A power control circuit with a power off time delay circuit for controlling an AC power supply to a microprocessor-based system is disclosed. The control circuit includes a relay, a switch unit, a DC power supply unit, a manually operable switch, and a time delay control circuit. The time delay control circuit is capable of controlling a turn-on and a delayed turn-off of the switch unit depending on the status of a DC operating voltage. When the manually operable switch is turned on, the AC power supply is supplied to the microprocessor-based system in a normal condition. When the manually operable switch is turned off, the AC power supply is still maintained to the microprocessor-based system for a predetermined delay time.
Claims6
A power control circuit for controlling an AC power supply through a pair of AC power lines to a microprocessor-based system having a central processing unit, comprising:
- a relay means having a coil and a normal open contact, the normal open contact being connected in series with one of the AC power lines;
- a switch unit connected in series to the coil of the relay;
- a DC power supply means for supplying a DC power supply;
- a manually operable switch connected in series with the DC power supply means for supplying a DC operating voltage from the DC power supply, the DC operating voltage being further supplied to the central processing unit through an operating voltage detection line;
- and
- a time delay control circuit for controlling a turn-on and a delayed turnoff of the switch unit in response to a status of the DC operating voltage;
- when the manually operable switch is turned on, the time delay control circuit outputting a triggering signal to control the switch unit to energize the coil of the relay, so that the normal open contact of the relay is closed and the AC power supply is supplied to the microprocessor-based system in a normal condition;
- and when the manually operable switch is turned off, the time delay control circuit keeps outputting the triggering signal to control the switch unit to energize the coil of the relay for a predetermined delay time, so that the normal open contact of the relay is closed and the AC power supply is supplied to the microprocessor-based system until the predetermined delay time has lapsed.
Dependencies are inferred from the claim text.