| 摘要 |
PURPOSE:To perform during a fixed term no protecting operation of an upper arm transistor from its overcurrent, by performing the resetting operation of the upper arm transistor synchronously with its ON-signal when its overcurrent is sensed, and by so performing the resetting operation of a lower arm transistor that its cutting-off is kept during the fixed term after the reception of its ON- signal when its overcurrent is sensed. CONSTITUTION:In a transistor 1 for driving a motor, etc., a current sensing terminal wherethrough the sensed current proportional to the main current of the transistor 1 flows is provided, and the sensed current can flow through a current sensing resistor 2. In the state wherein no overcurrent of the transistor 1 is sensed, the transistor 1 is driven PWM-wise via a driving circuit 3 by the intact signal inputted from an input terminal 6. But, in the state wherein the overcurrent of the transistor 1 is sensed, the sensed voltage of the current sensing resistor 2 increases, and it exceeds the preset voltage of a voltage comparator 4, and further, it sets a latching circuit 9. Thereby, a switching circuit 7 is operated, and the signal inputted from the input terminal 6 is stopped from being transferred to the driving circuit 3. |
