| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable to detect a mode switching signal inputted from exterior without newly providing a dedicated terminal. <P>SOLUTION: A control IC 10 has: a comparator CP1 that detects turn-off of a semiconductor switch Q1 from a voltage of an auxiliary coil N3, which is inputted to a zero-current detection terminal ZCD; a timer 21 that counts a predetermined time period from the turn-off detection; and a comparator CP2 that detects a second voltage signal different from a normal first voltage signal at the time when the semiconductor switch Q1 is in on state, from a voltage inputted to a current detection terminal IS. The second voltage signal supplied by mode switching circuits 15a and 15b can be detected with an existing current detection terminal IS. By detecting the second voltage signal after a lapse of the predetermined time period from the turn-off of the semiconductor switch Q1, an operation mode can be switched over, for example, by an overcurrent limitation threshold level change circuit 28 without newly providing a dedicated terminal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
