Solid state optically coupled power switch with light induced or modified voltage applied or removed at one or more MOSFET gate and source electrode pairs to shift each MOSFET between its high and low impedance states and in various circuit arrays for ac or dc switching and/or cross points switching or mechanical Form C relay substitution or other purposes

Solid state optically coupled electrical power switch

Clamping device of material tester for executing repetitive stress test and repetitive elongation test under high temperature condition

PURPOSE:To attain a quick action and to protect the gate of a output MOSFET by using a normally-on type drive transistor and discharging charges accumulated in the gate of the output MOSFET. CONSTITUTION:The titled relay has an output field effect MOSFET 3 and the normally turned-on type drive transistor 5. The former is impressed between a gate and a substrate and changes a 1st impedance state to a 2nd one. In the transistor 5, a pair of conductive electrodes are connected between the gate and substrate of the MOSFET 3, and a control electrode is connected at a connection point between an impedance element and a photoelectromotive force diode array 2. Besides that, the transistor 5 is biased by a voltage arising on the both ends of the impedance element when the photoelectromotive force diode arary 2 generates photoelectromotive force. Thus a quick action is attainable. There are a few errors such as instantaneous conduction which is caused by impressing an instantaneous change in a voltage on a relay output terminal if no input current flows. Moreover, the gate of the MOSFET 3 can be protected.

Solid-state relay and its manufacture

Drive circuit for power field effect switching transistor

Solid element relay circuit

PURPOSE:To break the high speed of an FET and to reduce the power consumption of a drive circuit by forming the third coil in a transformer, and abruptly discharging the charge of a gate capacity at the time of interrupting the FET. CONSTITUTION:A parallel circuit of the tertiary coil 33 of a transformer 3, a resistor 7 and a capacitor 8, and a switching element 6 are connected in series with a power source 1, the starting end of the coil 33 is connected to the collector of the element 6, and when the element 6 is conducted, a current which reversely excites a magnetic core is flowed. The element 3 is conducted simultaneously upon breaking of the switch element 2, a negative voltage is induced at the secondary coil 32, charge which is stored in the gate capacity of an FET 5 is abruptly discharged through the coil 33, and the FET5 is interrupted at a high speed. The resistor 4 can be sufficiently large or removed, the power consumption can be ingored, and power consumption of the resistor 7 may be sufficiently low, the power consumption of the drive circuit is reduced, the configuration is made simple and the operating characteristics can be preferably adapted for a practical use.

Oguchi Taisuke

Papers

Drive circuit for field effect transistor