| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a load drive circuit provided with a low-voltage state output off function that is satisfactorily in operation, even if the load drive circuit is interposed in a power supply path whose power supply voltage is temporarily changed due to a sudden change in a load current. SOLUTION: A charge pump circuit 17 receives a battery voltage Vb of a power supply line 13 and outputs a boosted voltage Vc which is nearly proportional to the battery voltage Vb. A low voltage detection circuit 19 detects a low-voltage state, where a detected voltage Va obtained by dividing the boosted voltage Vc is lower than a reference voltage Vr, so as to indirectly detect a low voltage state where the battery voltage Vb is lower than a prescribed threshold voltage. When the detection circuit 19 detects the low-voltage state, a drive circuit 18 drives a MOSFET 15 to be turned of. In this case, although the battery voltage Vb fluctuates temporarily, since a charge pump circuit 17 has a filtering action and a delaying action, the temporary fluctuation hardly appears in the boosted voltage Vc (detected voltage Va), thereby preventing the malfunction of the MOSFET 15.</p> |
