| 摘要 |
PURPOSE:To prevent malfunction or runaway of a load driving circuit and an equipment at the load side by incorporating a protection circuit detecting the moment of disconnection between a ground terminal of an integrated circuit and a ground terminal at the outside of the integrated circuit, and controlling an output switching element to be in OFF state, into the integrated circuit. CONSTITUTION:When the connection of a ground terminal 14 of an integrated circuit and a ground terminal 21 at the outside of the integrated circuit to the ground is broken, at first a control input terminal of an output switching element 11 is electrically floated and the output level of the element 11 rises. In such a way, the output of an output interrupt circuit goes to an L level at the decrease in the power supply to turn off the element 11. As a result, the output level of the element 11 is largely drawn toward the negative polarity with a counter electromotive force produced in a load 20. In such a case, a ground terminal disconnection detection circuit 31 detects an overvoltage to generate a ground terminal disconnection detection signal. Then an input signal interrupt circuit 34 controls the output switching element 11 to the OFF state based on the ground terminal disconnection deciding signal. |
