| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply apparatus for electronic equipment for eliminating the generation of noise from a DC-DC converter by stopping the operation of the DC-DC converter activated by a remote feeding source in a state of feeding power from a commercial power supply. <P>SOLUTION: When a local feeding section 2 applies an output voltage VDC to a DC-DC converter stop control section 5, the voltage VDC lights a light emitting diode 51a of a photocoupler 51 to turn on a photo transistor 51b of the photocoupler 51 and to control an input terminal 35a of a low voltage malfunction preventing circuit 35 in the DC-DC converter 3 to be at a low level. When a level at the input terminal 35a is a reference voltage VK or below, the low voltage malfunction preventing circuit 35 acts like stopping the switching operation of the DC-DC converter 3. In the case of feeding from a commercial power supply, the operation of the DC-DC converter 3 is stopped by the DC-DC converter stop control section 5 provided with the photocoupler 51 to eliminate the generation of noise from the DC-DC converter 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
