Patent ID: 7123045

Claim:
A semiconductor integrated circuit device comprising: an output stage including a first transistor which is fed with a first direct current voltage at its first electrode, a control electrode of the first transistor being used as an input of the output stage and a second electrode of the first transistor being used as an output of the output stage; and a clamp circuit restricting an input voltage to the control electrode of the first transistor in the output stage, wherein the clamp circuit includes: a second transistor which is fed with the first direct current voltage at its first electrode, in which a second electrode and a control electrode are connected each other; a switch connected at its one end to the second electrode of the second transistor; a constant current source which is connected at its one end to the other end of the switch and is fed with a second direct current voltage different from the first direct current voltage at the other end; and a diode which is connected between the control electrode of the first transistor and the other end of the switch, wherein the switch turns off when the output voltage from the second electrode of the first transistor approaches closely the first direct current voltage than a predetermined voltage, and wherein when the switch is in the ON state, the clamp circuit restricts the input voltage to the control electrode of the first transistor, and when the switch is in the OFF state, the input voltage to the control electrode of the first transistor is input to the control electrode of the first transistor without being restricted even though the input voltage is within the range which is restricted by the clamp circuit.