Power supply system for an electronic apparatus having memory
First Claim
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1. A power supply circuit for supplying electrical power to an electronic apparatus having a memory device comprising:
- p1 (a) a main power unit connected to an external power source and said apparatus for supplying necessary power to said apparatus in response to the operation of a switching means;
(b) an auxiliary power unit connected to said external power source and said apparatus for supplying power necessary for said memory device to retain stored information at least during an off-state of said main power unit;
(c) a battery serving as a back-up of said auxiliary power unit and main power unit for supplying power to said memory device for retaining stored information;
(d) detection means for detecting the output voltage of said auxiliary power unit; and
(e) power shut-off means which cuts off the power supply from said auxiliary power unit to said memory device upon expiration of a predetermined time after said detection means has detected a falling voltage.
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Abstract
A power supply system includes a main power unit for supplying power necessary for the operation of an electronic apparatus including a memory, an auxiliary power unit for supplying power necessary for retaining the memory contents, and a battery serving as a back-up of said main and auxiliary power units for supplying power necessary for retaining the memory contents. The memory is supplied with power from the main power unit when it is in the power-on state, from the auxiliary power unit when the main power unit is in the power-off state, and from the battery in the event of a.c. power failure.
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8 Claims
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1. A power supply circuit for supplying electrical power to an electronic apparatus having a memory device comprising:
- p1 (a) a main power unit connected to an external power source and said apparatus for supplying necessary power to said apparatus in response to the operation of a switching means;
(b) an auxiliary power unit connected to said external power source and said apparatus for supplying power necessary for said memory device to retain stored information at least during an off-state of said main power unit; (c) a battery serving as a back-up of said auxiliary power unit and main power unit for supplying power to said memory device for retaining stored information; (d) detection means for detecting the output voltage of said auxiliary power unit; and (e) power shut-off means which cuts off the power supply from said auxiliary power unit to said memory device upon expiration of a predetermined time after said detection means has detected a falling voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- p1 (a) a main power unit connected to an external power source and said apparatus for supplying necessary power to said apparatus in response to the operation of a switching means;
Specification