Digital protection circuit and method for linear amplifier

Claim 1

A circuit for controlling operation of an amplifier which receives operating current and which has a control input for disabling the amplification of an applied signal in response to a signal applied to the control input thereof, the circuit comprising: p1 resistor means connected to supply operating current to the amplifier for producing a voltage drop thereacross representative of the operating current supplied thereto; comparator means coupled to receive said voltage drop for producing an output in response to said voltage drop exceeding a selected level; trigger means coupled to receive the output from said comparator means for operating in response thereto in one of two logic states, said trigger means including an input for receiving an input applied thereto to activate operation thereof in another of said two logic states; timing means operable for a selected time interval in response to a signal applied thereto, said timing means being coupled to said trigger means and producing an output indicative of operation thereof for said time interval in response to said trigger means operating in said one logic state; means coupling the output of said timing means to said input of said trigger means to activate operation thereof in said other logic state; and gating means coupled to said trigger means and to said timing means for producing the signal for application to the control input to disable the amplifier in response to said trigger means operating in said one logic state or said timing means operating in said timing interval.