Patent ID: 8363372
Filing Date: 2013-01-29
Classification: H03K

Abstract:
1. A protection circuit that is connected between a power supply terminal and an output terminal, and turns off an output transistor when an abnormality occurs in a system, the output transistor outputting a current to a load connected to the output terminal, the protection circuit comprising: a first discharge unit that is connected between a gate electrode of the output transistor and the power supply terminal, and discharges an electric charge of the gate electrode until a potential of the gate electrode becomes equal to a power supply potential, when an abnormality occurs in the system; a second discharge unit that is connected between the gate electrode and a source electrode of the output transistor, and discharges the electric charge of the gate electrode until the potential of the gate electrode becomes equal to an output potential, when an abnormality occurs in the system; and a normal turn-off circuit that is connected between the gate electrode and the source electrode of the output transistor, and includes a depletion-type transistor that turns off the output transistor when the system is in a normal state.