| 摘要 |
A switching power supply includes a first auxiliary power supply for causing a first auxiliary winding of a transformer to induce voltage by ON/OFF control of a switching element connected to a primary winding of the transformer. The voltage induced by the first auxiliary winding charges a capacitor in the first auxiliary power supply. The switching power supply also includes a control circuit for starting and stopping the ON/OFF control of the switching element by comparing a voltage of the capacitor with a first threshold value, an activation circuit for charging the capacitor with voltage from the power supply input to the switching power supply, and a determination unit for determining a lifespan of the switching power supply based on the voltage of the capacitor after the voltage of the capacitor becomes greater than or equal to the first threshold value.
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