| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply unit and a lighting apparatus for suppressing the abnormal heating of an impedance element connected to a collector when a short circuit is made between the collector and a base of a transistor. SOLUTION: A power supply unit 1 is provided with a rectifier circuit 3 (first power supply element) which outputs a DC voltage Vin; a series circuit (first impedance element) of a plurality of LEDs 8 whose one end is connected to the output end of the high potential side of the rectifier circuit 3; an npn type transistor 7 whose collector is connected to the other end of the series circuit; a resistor 6 inserted between the emitter of the transistor 7 and the output end of the low potential side of the rectifier circuit 3; and a Zener diode 5 (second power supply element) inserted between the output end of the low potential side of the rectifier circuit 3 and the base of the transistor 7. Then, a diode 9 blocks currents flowing from the base of the transistor 7 to the Zener diode 5. COPYRIGHT: (C)2009,JPO&INPIT
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