Patent ID: 6710632
Filing Date: 2004-03-23
Classification: H03K

Abstract:
A drive circuit to supply drive current to a load resistor that is connected to a first power voltage supply terminal, comprising:a current output MOS transistor connected in series with the load resistor, a drive part that is connected to a second power voltage supply terminal, and that supplies a drive signal to the gate terminal of the current output MOS transistor, and a clamp circuit that is connected to the second power voltage supply terminal to hold the drain terminal of the current output MOS transistor at a predetermined potential, wherein the clamp circuit comprises: a first MOS transistor that is connected between the gate terminal and the drain terminal of the current output MOS transistor, a second MOS transistor in which the gate terminal and the drain terminal are connected together and in which said gate terminal is connected to the gate terminal of the first MOS transistor, a rectifying element that is connected between the gate terminal of the current output MOS transistor and the first MOS transistor, or between the first MOS transistor and the drain terminal of the current output MOS transistor, and a voltage holding circuit that is connected to the source terminal of the second MOS transistor and that holds the potential of said source terminal at a predetermined voltage.