Controller for vehicular lamp

摘要

To reduce manufacturing costs by suppressing a ground fault current, a controller for a vehicular lamp includes an inverting converter 2 for supplying power to LEDs 21-1 to 21-n, and a current detection unit 3 that includes a shunt resistor Rs connected serially to the LEDs 21-1 to 21-n and detects an LED driving current flowing through the LEDs 21-1 to 21-n. The current detection unit 3 includes a shunt resistor Rs' connected serially to the LEDs 21-1 to 21-n via the shunt resistor Rs, and a bypass section 4. The bypass section 4 includes an NMOS transistor 10 connected parallel to the shunt resistor Rs' and a Zener diode ZD1 that causes the NMOS transistor 10 to turn off when a ground fault occurs at a positive polarity output side or a negative polarity output side of the inverting converter 2.