Patent ID: 7535127

Claim:
A solid state relay circuit comprising: a converter circuit coupled to a control input of the solid state relay circuit for converting the control input to a level shifted alternating voltage output; a transformer coupled to the output of the converter circuit for providing isolation; a rectifier coupled to an output of the transformer for conversion to a rectified and level shifted voltage output; a capacitance circuit coupled to an output of the rectifier; a power transistor having a control input, the power transistor is a plurality of power transistors having drain and sources coupled in parallel and having control inputs coupled in common to the charge and discharge transistors; charge and discharge transistors coupled between the capacitance circuit and the control input of the power transistor; and a control circuit having inputs coupled to an output of the rectifier and the capacitance circuit and having outputs coupled to control the charge and discharge transistors, the charge and discharge transistors are controlled by the control circuit such that capacitors in the capacitance circuit provide sufficient charge time to quickly turn on and discharge time to quickly turn off the power transistor by discharging or charging an equivalent capacitance at the control input of the power transistor.