EP0187369A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Power supply system for an electronic apparatus having memory
Assignee: Hitachi Ltd
•
Filing: 1985-12-23
•
Granted: —
•
Expires: 2005-12-23
Abstract
Abstract A power supply system includes a main power unit (8) for supplying power necessary for the operation of an electronic apparatus including a memory, an auxiliary power unit (9) for supplying power necessary for retaining the memory contents, and a battery (V a ) serving as a back-up of said main and auxiliary power units for supplying power necessary for retaining the memory contents. The memory (4) is supplied with power from the main power unit (8) when it is in the power-on state, from the auxiliary power unit (9) when the main power unit is in the power-off state, and from the battery (V B ) in the event of a.c. power failure.
Inventors
- 👤 Kazuo Morita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 09:54
CPC Classifications
G; G11; G11C; G11C5/00; G11C5/14; G11C5/141; G06; G06F; G06F1/00; G06F1/26; G06F1/30; H; H02; H02J; H02J9/00; H02J9/04; H02J9/06; H02J9/061
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
117 words
A power supply circuit for supplying electrical power to an electronic apparatus having a memory device (4) comprising: (a) a main power unit (8) connected to an external power source (Vin) and adapted to supply necessary power to said apparatus in response to the operation of a switching means (7); (b) an auxiliary power unit (9) connected to said external power source and adapted to supply power necessary for said memory device for retaining stored information at least during an off-state of said main power unit; and (c) a battery (V B ) 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.
Claim 2
Dependent Claim
117 words
A power supply circuit for supplying electrical power to an electronic apparatus having a memory device (4) comprising: (a) a main power unit (8) connected to an external power source (Vin) and adapted to supply necessary power to said apparatus in response to the operation of a switching means (7); (b) an auxiliary power unit (9) connected to said external power source and adapted to supply power necessary for said memory device for retaining stored information at least during an off-state of said main power unit; and (c) a battery (V B ) 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.
Claim 3
Dependent Claim
24 words
A power supply circuit according to claim 1, wherein said main power unit is connected to said external power source through said switching means.
Claim 4
Dependent Claim
55 words
A power supply circuit according to claim 2 further comprising a first means (ZDl, Rl) for detecting the output voltage of said main power unit and a switch means (Ql, Q2, Q3) for connecting said auxiliary power unit to said memory device in response to the detection of a falling voltage by said first means.
Claim 5
Dependent Claim
59 words
A power supply circuit according to claim 3, wherein said auxiliary power unit, said battery and said switch means have a common connection point, said circuit further comprising a charging means (5) for charging the output of said auxiliary power unit to said battery and a current unidirectional means (D3) connected between said common connection point and said battery:
Claim 6
Dependent Claim
30 words
A power supply circuit according to claim 4, wherein said auxiliary power unit provides an output voltage which is higher than or equal to the output voltage of said battery.
Claim 7
Dependent Claim
63 words
A power supply circuit according to claim 1 further comprising a second detection means (ZD2, R4) for detecting the output voltage of said auxiliary power unit and a power shut-off means (20) which cuts off the power supply from said auxiliary power unit to said memory device upon expiration of a predetermined time after said second detection means has detected a falling voltage.
Claim 8
Dependent Claim
88 words
A power supply circuit according to claim 6, wherein said power shut-off means comprises a means which cuts off the power supply from said battery upon expiration of a first time length if said second detection means has detected a falling voltage during a halt state of said apparatus, or cuts off the power supply from said battery upon expiration of a second time length longer than said first time length if said second detection means has detected a falling voltage during an operating state of said apparatus.
Claim 9
Dependent Claim
15 words
A power supply circuit according to claim 6, wherein said memory device comprises a DRAM.
Claim 10
Dependent Claim
28 words
A power supply circuit according to claim 8, wherein said apparatus further comprises an SRAM (6) which is connected to said battery so as to receive power uninterruptedly.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.