| 摘要 |
A SMPS(Switched Mode Power Supply) is provided to prevent malfunction of a digital device due to load difference between a standby mode and a normal operation mode by steadily supplying operating voltage to a switching IC. A SMPS comprises a transformer(40), a feedback unit(60), a switching IC(30), a comparator(80) and a switch(70). The comparator compares a secondary side output voltage level of the transformer with a burst level. The burst level is reference voltage in light-load. In case the secondary side output voltage level of the transformer is greater or smaller than the burst level, the comparator outputs law signals. In case the secondary side output voltage level of the transformer is the same as the burst level, the comparator outputs high signals. The first operating voltage(Vccl) or the second operating voltage(Vcc2) is output from the transformer. According to the output signal of the comparator, the switch performs the switching operation for inputting the first operating voltage or the second operating voltage to the switching IC as an operating voltage.
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