PURPOSE: To attain miniaturization and low cost by using heat dissipation of a resistive element for switch trigger and constituting a switch circuit with electrical isolation from a PNPN switch in the switch circuit for on/off control of large current or high voltage.
CONSTITUTION: A low level and a high level are set respectively to control signal input terminals 31, 21 in triggering the PNPN switch 1, a transistor TR18 is conductive and a heat dissipating energy of a resistive element 16 is fed to the PNPN switch 1 so as to trigger it. In turning off the PNPN switch 1, a control signal at the terminal 21 is brought into a low level and an external circuit interrupts a main current at the same time or a reverse bias is given between terminals 4 and 5. The off-state is kept stably by setting the terminals 31, 21 to a high level and a low level while the switch 1 is turned off. The trigger gate current is not leaked to the main current path by isolating electrically the trigger system comprising the resistive element 16, a power supply 17 and the TR18 from the PNPN switch 1.
TANABE MASAAKI
KIMURA TADAKATSU
SAKURAI TETSUTADA
| JPS5756423U | 1982-04-02 | |||
| JPS4841162B1 | ||||
| JPS587923A | 1983-01-17 |