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(11) | EP 2 200 406 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Controller for vehicular lamp |
(57) 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.
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