Abstract: A pad for input/output signals is formed on a first conductive type insulated island region interposing an insulating film therebetween. The insulated island region is electrically insulated and isolated from other semiconductor regions in a semiconductor substrate. A fixed potential is provided to the insulated island region through an n.sup.+ -type layer and an electrode. As a result, it is possible to prevent noise superimposed on the input/output signals from interfering in the operation of the other semiconductor regions, and to prevent noise produced in the other semiconductor regions from being superimposed on the input/output signals.

Abstract: An over-voltage protection apparatus includes a power feed line. A load has a given low impedance. A current supplying device operates for supplying a current to the load via the power feed line. A load drive device operates for controlling the supply of the current to the load by the current supplying device. An over-voltage detecting device operates for detecting an over-voltage at the power feed line. A discharge command device operates for, when the over-voltage at the power feed line is detected by the over-voltage detecting device, controlling the load drive device to enable a discharge current to flow from the power feed line into the load and thereby to remove the over-voltage from the power feed line through discharge. A current detecting device operates for detecting the discharge current.

Abstract: A driving circuit for the electromagnetic relay provides a coil of the electromagnetic relay with stepped voltage having a first voltage which is slightly larger than a minimum operating voltage which caused the coil to generate magnetic field capable of closing contacts of the electromagnetic relay and a second voltage higher than the first voltage, in response to a triggering signal to trigger the electromagnetic relay. According to this structure, because the first voltage lower than the second voltage is applied to the coil firstly, the contacts are closed by attracting force of the coil risen gently. As a result, the bouncing of the moving contact can be prevented. In addition, the response time required for the closing of the contacts can be prevented to become long.

Abstract: In a load actuation circuit of an emitter-follower circuit arrangement, a surge detection circuit detects a power surge voltage superposed on a power voltage of a power line. A feed circuit supplies current to a control electrode of an output transistor (i.e. emitter-follower transistor) from the power line to turn on the output transistor forcibly when any power surge voltage is detected by the surge detection circuit. Thus, the power surge voltage is absorbed by the output transistor.

Abstract: A load drive apparatus is used in a vehicle direction indicating apparatus operable free from overcurrents and overvoltage. The load drive apparatus includes: a charging/recharging capacitor; a charging/recharging circuit for charging/recharging the capacitor at a preselected time constant in such a manner that a voltage across the capacitor is varied between a preset upper limit voltage and a preset lower limit voltage; a drive circuit for turning ON a power transistor series-connected to a current path employed to supply a current from a DC power source to a load, thereby driving the load when the charging/discharging circuit causes the capacitor to be charged, or the voltage across the capacitor is higher than, or equal to a predetermined voltage defined between the upper limit voltage and the lower limit voltage; overcurrent judging means for judging whether or not a voltage across terminals of the power transistor connected to the above-described current path exceed an overcurrent judging voltage.