| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply device and a lighting device which maintain normal operation even if the voltage of a commercial power supply changes. SOLUTION: When a voltage V detected by a voltage detection unit 15 is lower than a first threshold Vth 1, an NPN transistor 158 is turned on to set a control terminal Ve at a low voltage level. As a result, an overload protection circuit 18 stops the operation of a switching circuit 17. When the voltage V detected by a voltage detection unit 15 becomes higher than the first threshold Vth 1, the NPN transistor 158 is turned off to set the control terminal Ve at a high voltage-level. As a result, the overload protection circuit 18 cancels the suspended operation of the switching circuit 17 to resume the operation. In this case, the first threshold Vth 1 is made greater than an off-latch occurrence threshold that is a voltage at which an overload state is detected at a resistance 181 as a result of an increase in current flowing through an FET 171 when the voltage V output from a smoothing circuit 13 drops. COPYRIGHT: (C)2010,JPO&INPIT
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