| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a constant voltage supply circuit to save power in portable communication equipment requiring a driving voltage higher than normal driving voltages for connection with other equipment. <P>SOLUTION: The constant voltage supply circuit 1 includes: a first regulator 6 for generating a first constant voltage from supply voltage; a second regulator 7 for generating a second constant voltage higher than the first constant voltage from supply voltage; and a switching circuit 9 connected to them. When an external terminal is not connected to a connecting terminal 8, the switching circuit 9 does not actuate the second regulator 7 and supplies only the first constant voltage to a first circuit 3 and a second circuit 4. When an external terminal is connected, the switching circuit 9 actuates the first regulator 6 and the second regulator 7 to supply the first constant voltage to the first circuit 3 and the second constant voltage to the second circuit 4. Thus, when an external terminal is not connected, unnecessary high voltage can be prevented from being supplied, and power saving can be achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT |
