| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a switching power supply device with higher output voltage accuracy while surge breakdown voltage is improved with a simple structure. <P>SOLUTION: The switching power supply device including a primary side circuit and a secondary side circuit includes: a detection circuit detecting output voltage of the secondary side circuit; and a relay circuit feeding back a detection result of the detection circuit to the primary side circuit in a state where the circuit is electrically insulated from the primary side circuit and the secondary side circuit. The detection circuit includes a first light emitting element emitting light in a light volume corresponding to the detected output voltage. The relay circuit includes a first light receiving element receiving light from the first light emitting element and generating current corresponding to the light volume; and a second light emitting element emitting the light in the light volume corresponding to a size of the current generated by the first light emitting element. The primary side circuit has a second light receiving element receiving light from the second light emitting element and generating the current corresponding to the light volume. The primary side circuit on/off-controls the current of primary winding based on the size of the current generated by the second light receiving element. <P>COPYRIGHT: (C)2012,JPO&INPIT |
