Short circuit protection circuit
AssigneeEssex Group, Inc.
InventorsRobert G. Yorks, David W. Junker
Life of this patent
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Abstract
In a circuit of the type in which a command signal actuates a semiconductor switch which, in turn, actuates a load device and in which a clock signal is available, a protection circuit for protecting the semiconductor switch located in series with the load from excessive current in the event the load device is short circuited. The protection circuit includes a sensing circuit for sensing the voltage level at a point intermediate the semiconductor switch and the load. The protection circuit interfaces between the command signal and the clock signal in such a manner that the semiconductor switch is repeatedly momentarily energized if the load is shorted and a command signal is present.
Claims5
In a switching circuit for controlling the application of power to a load including a semiconductor switch in series with said load connected across a source of power, means for providing a clock signal switching between first and second states, means for providing a command signal switching from a first state to a second state when it is desired to energize said load, a protection circuit for protecting said semiconductor switch in the event said load is short circuited, comprising:
- sensing circuit means for sensing the voltage across said load and for providing an output signal indicative of whether or not said load is shorted;
- and
- circuit means responsive to the output signal of said sensing circuit, said command signal and said clock signal for actuating said semiconductor switch when said command signal switches from said first state to said second state or shortly thereafter, said circuit means thereafter maintaining said semiconductor switch in said actuated state as long as said command signal remains in said second state and the output of said sensing circuit means indicates said load is not shorted, said circuit means momentarily energizing said semiconductor switch when said command signal is in said second state and the output of said sensing circuit means indicates said load is short circuited.
Dependencies are inferred from the claim text.