| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a compact and low cost step-down device and a power system having the same device, capable of preventing a decreased power output voltage when protecting it from an overcurrent and preventing overheat and a failure in a configuration member, when a power supply is included in a target to apply a step-down voltage.SOLUTION: A step-down device 1 decreases a voltage applied between the drain of an FET 11 and the source of an FET 12 by complementary on/off repetition of the FET 11, 12 functioning as switches, so that the step-down voltage is applied to a low voltage battery 22 connected between one end of a capacitor C2 of a coil L1 and the source of the FET 12. A melting circuit 14 switches on the FET 12 on detection of a short circuit in the FET 11, whereas switches off the FET 12 on detection of fusion of a fuse 10 after switching on the FET 12.</p> |
