Other

Hitachi, Ltd.

Hitachi Haramachi Semi-conductor, Ltd.

Haramachi Semi-hitachi Ltd.

Hitachi Conductor Ltd.

Hitachi Ltd. and Hitachi Haramachi Semi-conductor Ltd.

Shigeru Sugayama

Tadaaki Kariya

Tatsuo Shimura

Sigeo Tomita

Toshiki Kurosu

In order to provide a highly accurate and reliable temperature sensing circuit and method, a resistor (,) having a positive temperature coefficient is connected between the gate terminal (,) and the insulated gate electrode (,) of the voltage drive type semiconductor device (,), and the temperature is sensed based on a voltage representing a voltage drop across the resistor in a circuit portion between the gate terminal (,) and the other terminal (,).

Temperature sensing circuit for voltage drive type semiconductor device and temperature sensing method therefore, and drive-device and voltage drive type semiconductor device using the same

A fraction of current passing through the P-emitter region and N-base region of a thyristor is by-passed to the base-emitter junction of a PNP transistor. The amount of the base current is dependent on the thyristor current. Thus, as the anode current of the thyristor increases, the base current and hence the collector current of the PNP transistor increases. The collector current by-passed to the PNP transistor is fed, via a switch which is closed during the off-time of the thyistor, to the base-collector path of an NPN transistor whose collector and emitter are respectively connected to the gate and cathode of the thyristor. The turn-on voltage across the collector and emitter of the NPN transistor accordingly becomes lower than the gate-cathode voltage of the thyristor. The base-emitter current of the NPN transistor equals the collector current of the PNP transistor, the collector current being a fraction of the anode current by-passed to the PNP transistor. A fraction of the anode current of the turned-on thyristor is utilized as the control power for driving the NPN transistor so that additional external power for turning off the thyristor becomes almost unnecessary.

Semiconductor switching circuit

A voltage across a resistor of a small value connected in series with the cathode or anode of a thyristor is used as a signal source for overcurrent detection. When an overcurrent is generated, the voltage across the resistor increases in excess of the built-in voltage between the base and emitter of a transistor, thereby turning on the transistor. A transistor to take out a current from the gate of the thyristor is turned on. Thus, the self-turn off operation of the thyristor is executed.

Semiconductor switch

In a bidirectional linear switch in which two MOS transistors are used with their sources mutually connected, the gates and the substrates of the transistors are also respectively mutually connected and a control signal is applied to the gates. A potential of the polarity such that the substrates are reversely biased to the sources is applied between the substrates and the sources. With this constitution, the linearity of the bidirectional switch is improved.

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Hitachi, Japan

Shigeru Sugayama