| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a semiconductor switching element drive circuit that reliably actuates an overcurrent protection circuit even when a current value limited by a short circuit protection circuit fluctuates, while suppressing increases in cost and size. <P>SOLUTION: The semiconductor switching element drive circuit includes: a semiconductor switching element Q1 for passing a main current between a first terminal and a second terminal upon voltage application to a gate terminal; an overcurrent protection circuit OP for determining that the main current is an overcurrent exceeding a predetermined current value for a predetermined time, and lowering the main current, when a current value or voltage value proportional to the magnitude of the main current exceeds a threshold; a short circuit protection circuit SP for lowering the gate voltage applied to the gate terminal more rapidly than the overcurrent protection circuit lowers the main current, when the main current becomes an overcurrent higher than the overcurrent in a shorter time than the predetermined time; and a threshold change circuit TC for reducing the threshold while the short circuit protection circuit lowers the main current. <P>COPYRIGHT: (C)2013,JPO&INPIT |
