| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply unit, capable of using a common transformer without depending on AC voltage of commercial power supply, and preventing generation of fluctuations in output voltage or maximum output voltage, even if the AC voltage of commercial power supply changes. SOLUTION: This switching power supply unit is provided with a primary winding 1a of a transformer 1 consisting of two coils L1, L2, so that even if the connection of the respective coils L1, L2 is changed according to the AC voltage of commercial power 3, both of the output voltage and maximum output power supplied to load 6 can be kept constant. Additional use of a transformer 1 for each different AC voltage can be eliminated, thereby attaining parts cost reduction and downsizing of the power supply unit.
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