Patent ID: 7295039

Claim:
A buffer circuit for use with high-potential and low-potential power supplies, the buffer circuit comprising: a power supply circuit for generating reference voltage, the power supply circuit including: a first transistor circuit, connected to the high-potential power supply, having an on-resistance adjusted to be relatively small; a second transistor circuit, connected between the first transistor circuit and the low-potential power supply, including a gate and a source connected to each other, wherein the reference voltage is the voltage at a node between the first transistor circuit and the second transistor circuit; and a protection circuit, directly connected to both of the first transistor circuit and the second transistor circuit, having sufficient resistance for reducing current flowing to the second transistor circuit, wherein the buffer circuit outputs the reference voltage from a node between the first transistor circuit and the protection circuit or a node between the second transistor circuit and the protection circuit.