| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive protection circuit that can detect anomalies other than a dead short circuit of a load in a switching power circuit. <P>SOLUTION: A transistor Q1 switches a DC voltage resulting from rectification of an AC voltage from a commercial power supply 1. A switching control IC 3 controls the pulse width of a drive pulse to the transistor Q1 so as to keep an output voltage output from a secondary side of a switching transformer T constant. An anomaly detection circuit 10 detects the pulse width of the drive pulse to the transistor Q1, and if the pulse width deviates from an allowable range, instructs the switching control IC 3 to perform a protective action of stopping the operation of the transistor Q1. <P>COPYRIGHT: (C)2012,JPO&INPIT |
