| 摘要 |
A power supply device capable of preventing a drive transistor from being damaged by heat when a collector output is grounded. A power supply device (10), which supplies for driving a drive current to the base of a transistor (20), has a lower-limit threshold value comparison unit (14) for comparing an actual collector output Vin with a lower-limit threshold value 0.5Vref of the transistor (20), and, when the collector output Vin is less than the lower-limit threshold value 0.5Vref, issuing a stop signal to a current control unit (18). Therefore, since the collector output of the transistor (20) grounding without intermediary of a load circuit (40) lowers the collector output Vin below the lower-limit threshold value 0.5Vref, the current control unit (18) receives a stop signal from the comparison unit (14) to stop the supply of a drive current to the transistor (20), thereby preventing damage to the transistor (20) by heat.
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