Patent ID: 8476891

Claim:
A constant current circuit, comprising: a constant current circuit section comprising: a first transistor including a source connected to a first power source; a second transistor including a drain and a gate which are connected to a drain of the first transistor, and a source connected to a second power source; a third transistor including a source connected to the first power source, and a drain and a gate which are connected to a gate of the first transistor; and a fourth transistor including a source connected to a first resistor, a gate connected to the gate and the drain of the second transistor, and a drain connected to the gate and the drain of the third transistor, the first resistor including one end connected to the source of the fourth transistor and another end connected to the second power source; and a start-up circuit comprising: a fifth transistor including a source connected to the first power source, and a gate connected to the gate of the second transistor; a sixth transistor including a source connected to the second power source, and a gate connected to the gate of the second transistor; and a seventh transistor including a gate connected to a drain of the fifth transistor and a drain of the sixth transistor, a drain connected to the gate of the third transistor, and a source connected to the second power source.