POWER SUPPLY DEVICE, DISCHARGE LAMP-LIGHTING SYSTEM, AND LIGHTING SYSTEM

摘要

PROBLEM TO BE SOLVED: To reduce generation of unbalance and connection failures by inputting the DC voltage of a DC power supply device for alternately turning on and off for switching, and by setting voltage applied between the gate and the source of a P-type FET to be larger than that for an N-type FET for alternately turning on and off a switching device. SOLUTION: Switching devices 7 and 8 connected in series with each other are provided between the output terminals of a DC voltage device 1. The source of an N-type FET 7 is connected to that of a P-type FET 8, and their gates are also mutually connected. A drive means 9 applies a voltage between the gate and the source of the FETs 7 and 8, and alternately turns on and off the FETs 7 and 8. The output of the drive means 9 sets the voltage applied between the gate and the source of the P-type FET 8 to be larger than that being applied between the gate and the source of the N-type FET 7 and decreases the on-resistance of the P-type FET 8 corresponding to the increase in the voltage which is applied between the gate and the source, thus allowing the calorific values of the FETs to approach, and hence providing heat radiation countermeasures and balancing the service life.