| 摘要 |
PROBLEM TO BE SOLVED: To provide a protective circuit which uses a short circuit of the output terminal of an adaptor, which countermeasures against heating is not required, due to control of the output current. SOLUTION: There are provided a current output switching transistor (Tr3), whose emitter is connected to a power supply (VCC) and whose collector is connected to an output terminal (OUT); a first switching transistor (Tr1) which is turned on, when a differential voltage (ΔVF1) between the voltage of the power supply and an output voltage exceeds a usable range; a second switching transistor (Tr2) which is turned on, when the first transistor is turned on; a switching control amplifier which controls turning off of the current output switching transistor (Tr3), when the voltage of the power supply (VCC) is lowered to a value which is not higher than a prescribed value; and a constant current control amplifier which carries out constant current control, when the second switching transistor (Tr2) is turned on, and a protective operation state is realized.
|
