Sumitomo Electric Industries, Limited

Sumitomo Wiring Systems, Limited

Autonetworks Technologies, Limited

Yusuke Yano

Katsuma Tsukamoto

Keisuke Wakazono

In a switch circuit for use in a vehicle, conduction between a drain electrode and a gate electrode of each of a first main transistor and a second main transistor is switched on or off depending on a voltage between the gate electrode and a source electrode. A first surge protection device is connected between the drain electrodes of the first main transistor and the second main transistor. The first surge protection device keeps a voltage that is applied to the first surge protection device at a first predetermined voltage or lower. A sub transistor is provided between the gate electrodes and the source electrodes of the first main transistor and the second main transistor. The sub transistor is turned on when the first main transistor and the second main transistor are turned off.

Switch circuit and power supply system

Provided is a power supply device configured to diagnose circuit operation, and identify, if a defect is found in the diagnosis, the circuit component that is the cause. The power supply device includes: a switch that is disposed in a power supply path leading from a main power source to a load, and is configured to bring into conduction and interrupt the power supply path; a downstream sensing means for sensing a power supply state of a load-side power supply path between the switch and the load; a comparing means for comparing a downstream voltage of the load-side power supply path, with a predetermined threshold voltage; and a control unit. The control unit includes: a switch control means for turning the switch on/off; and a conduction determination means for determining whether the switch is in an ON or OFF state based on the output of the downstream sensing means.

Power supply device

An overcurrent protection circuit that can cope even with a case where a ground fault occurs in a mask time period for overcurrent detection. The overcurrent protection circuit detects, when a switching element is on, a differential voltage value between both ends of the switching element that is caused by an electric current flowing therethrough, and turns off the switching element when the detected differential voltage value is larger than a predetermined voltage value. A detection circuit that detects respective voltage values at both ends of the switching element, and means for preventing the switching element from being turned on if either of the respective voltage values detected by the detection circuit is less than a predetermined value.

Overcurrent protection circuit

A current flows between the drains of FETs, which function as a switch. A first constant current circuit causes a constant current to flow from the FET side of a resistor to the other side thereof. A first comparator outputs a high level voltage to the control section if the electric potential at the drain of the FET is higher than the electric potential at one end, on the first constant current circuit side, of the resistor. Furthermore, the first comparator outputs a low level voltage to the control section if the electric potential at the drain of the FET is lower than the electric potential at one end, on the first constant current circuit side, of the resistor. The control section turns the FETs off when the first comparator outputs the low level voltage. Furthermore, the control section changes the current that is caused to flow through the resistor by the first constant current circuit.

Preventive apparatus

A semiconductor device is provided in which burning of a semiconductor element can be prevented without incorporating a fuse. The semiconductor device, which includes a plurality of semiconductor elements that are connected in parallel between a direct current power source and a load, is configured to simultaneously turn ON or OFF the plurality of semiconductor elements. The semiconductor device includes a voltage detection means for detecting a voltage value across a fixed potential and a connection node for the plurality of semiconductor elements and for the load, a determining means for determining, if the semiconductor elements are OFF, whether or not a voltage value detected by the voltage detection means is higher than a predetermined voltage value; and a means for turning the plurality of semiconductor elements ON when the unit determines that the detected voltage value is higher than the predetermined voltage value.

Growing community of inventors

Mie, Japan

Yusuke Yano