US Patent 7576345 Semiconductor relay

The semiconductor relay comprises: an insulated type DC/DC power supply 10 having the input terminal and the output terminal insulated from each other; a pulse transformer 20 having the input terminal and the output terminal insulated from each other; an analog switch 30 which turns on and off the circuit in accordance with a state of an input signal; and a MOSFET circuit 40 which turns on and off a high voltage to a load 50. When a pulse signal is outputted from a pulse signal source 28, the pulse signal is outputted from the pulse transformer 20, and a state of the analog switch 30 is switched, a supply voltage is outputted from the output terminal of the analog switch 30, both the MOSFETs 42, 44 of the MOSFET circuit conduct, and a high AC voltage is applied to a load 50 from an AC power supply 52. Then, when a pulse signal is outputted from the pulse signal source 28, the pulse signal is outputted from the pulse transformer 20, the state of the analog switch 30 is switched, a ground voltage is outputted from the output terminal of the analog switch 30, both the MOSFETs 42, 44 of the MOSFET circuit are turned off, and the high AC voltage from the AC power supply 52 is not applied to the load 50.