To provide a specific constitution which surely charges a battery unit by DC power fed to a body device from an AC adapter, when the body device is brought into a power-off state.
When a power supply 31 for power supply attached to the body device 2 in the power-off state is charged, a power feed control terminal 1b is initially controlled to a low level until a charging/discharging capacitor 205 is charged to a constant voltage, by using the voltage of an output terminal 1a of the AC adapter 1, and the DC power supply of the AC adapter 1 is initially controlled to a power supply voltage of the body device 2, which is necessary for charging the power supply 31 for power supply. Then, the power feed control terminal 1b is held at a low level by starting a charging circuit 204, and the DC power supply of the AC adapter 1 is maintained at the power supply voltage of the body device 1. Furthermore, when the power supply plug of the AC adapter 1 is wrongly pulled out of a power receptacle and reinserted into it and so forth, the power feed control terminal 1b is initially controlled, without fail, to the low level by sort-circuiting and discharging the charging/discharging capacitor 205 by using a reset circuit 218.
COPYRIGHT: (C)2010,JPO&INPIT
| JP2003072057A | ||||
| JP2005278272A |
Osamu Suzawa
Kazuhiko Miyasaka