| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-cost LED drive circuit that allows optimally driving LEDs.SOLUTION: An on-vehicle LED drive circuit 10 includes two LEDs 13 connected in series to each other and a transistor Q1 connected in series to the LEDs 13, and is a constant-current circuit that constant-current-drives the LEDs 13 by controlling a current flowing through the transistor Q1 to a constant current value. The LED drive circuit 10 further includes a resistor R1 for detecting a current flowing through the transistor Q1, and a transistor Q2 feedback-controlling the transistor Q1 according to a voltage across the resistor R1. The LED drive circuit 10 further includes a constant-voltage circuit 14 generating a constant voltage from a power-supply voltage of an on-vehicle battery 11 and supplying the constant voltage to circuit configuration members (the constant current circuit, the resistor R1, and the transistor Q2). |
