| 摘要 |
Disclosed is a power supply circuit for vehicles, which can continuously supply a constant voltage without a complicated circuit configuration, even during a time when a surge voltage is applied (abnormal voltage time). The power supply circuit is provided with: a constant voltage circuit (3), which is connected to a battery mounted in a vehicle, and which outputs a predetermined voltage; a surge cut circuit (2), which is provided with a zener diode (2a) and a transistor (2c) for protecting the constant voltage circuit (3); and a switching circuit (1), which is disposed between the constant voltage circuit (3) and the surge cut circuit (2), and which performs on/off switching of output to the constant voltage circuit (3). The power supply circuit is also provided with a feedback line that connects the connecting line (output line) (c) of the switching circuit (1) and the zener diode (2a) to each other.
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