Title:
POWER SUPPLY BACK UP CIRCUIT OF PORTABLE TELEPHONE
Document Type and Number:
Japanese Patent JP3781720
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To enable high level setting of charging voltage of a lithium battery, enable increase of charging capacity, and enable prolonging operating time of a storage device and an RTC circuit in the state that a battery pack is detached.
SOLUTION: When the battery pack 2 is not attached, a voltage is applied from the lithium battery 1 to the storage device 9 and the RTC circuit 10 via a switch 5. When the battery pack 2 is attached, a voltage is applied to the storage device 9 and the RTC circuit 10 via a regulator 8 and a diode 11, and the lithium battery 1 is charged via the regulator 3 and a switch 4. The switches 4, 5 are subjected to on/off control by output from a battery pack detecting circuit 6 and opened and closed. A signal wherein logical value of output of the battery pack detecting circuit 6 is reversed is input to the switch 4 via an inverter 7. The switch 5 performs reversed opening and closing of the switch 4. Outputs of the regulators 3, 8 are separated from each other by the switches 4, 5. It becomes unnecessary for output voltages of the regulators 3, 8 to be the same, and charging voltage of the lithium battery 1 can be made high.
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Inventors:
Oguri Shinji
Application Number:
JP2002344125A
Publication Date:
May 31, 2006
Filing Date:
November 27, 2002
Export Citation:
Assignee:
Saitama NEC Corporation
International Classes:
H02J7/00; H02J9/06; H01M10/44; H04B7/26; (IPC1-7): H02J9/06; H01M10/44; H02J7/00; H04B7/26
Domestic Patent References:
| JP62088426U | ||||
| JP5095634A | ||||
| JP5183463A | ||||
| JP3066904Y2 | ||||
| JP62088426U |
Attorney, Agent or Firm:
Masahiko Desk
Masashi Kudo
Yasuhisa Tanizawa
Masashi Kudo
Yasuhisa Tanizawa