초록 ▼

In a load actuation circuit of an emitter-follower circuit arrangement, a surge detection circuit detects a power surge voltage superposed on a power voltage of a power line. A feed circuit supplies current to a control electrode of an output transistor (i.e. emitter-follower transistor) from the po

In a load actuation circuit of an emitter-follower circuit arrangement, a surge detection circuit detects a power surge voltage superposed on a power voltage of a power line. A feed circuit supplies current to a control electrode of an output transistor (i.e. emitter-follower transistor) from the power line to turn on the output transistor forcibly when any power surge voltage is detected by the surge detection circuit. Thus, the power surge voltage is absorbed by the output transistor.

대표청구항 ▼

[ What is claimed is:] [1.] A load actuation circuit with a surge protection function comprising:an output transistor having a collector receiving a power voltage from a power line, an emitter connected to one end of a load that is grounded at the other end, and a control electrode;a control circuit

[ What is claimed is:] [1.] A load actuation circuit with a surge protection function comprising:an output transistor having a collector receiving a power voltage from a power line, an emitter connected to one end of a load that is grounded at the other end, and a control electrode;a control circuit for controlling an electric potential of said control electrode of said output transistor to turn on or off said output transistor;a surge detection circuit connected between said power line and a ground line in parallel with said output transistor for detecting a power surge voltage superposed on said power voltage of said power line, said surge detection circuit including a constant-voltage diode; anda feed circuit responsive to a surge detection voltage of said surge detection circuit for supplying a current to said control electrode of said output transistor from said power line to turn on said output transistor when any power surge voltage is detected by said surge detection circuit, said feed circuit causing a voltage drop between said collector and said control electrode of said output transistor when said output transistor is turned on in response to said surge detection voltage of said surge detection circuit, said voltage drop at said output transistor being smaller than a voltage drop at said constant-voltage diode of said surge detection circuit.