| 摘要 |
PROBLEM TO BE SOLVED: To supply a stable output voltage from a power supply device having switching power supply and a series power supply, even if a load whose load current fluctuates greatly is connected to a device. SOLUTION: An error transformer 1 for feedback control has a 1st threshold and a 2nd threshold which is lower than the 1st one. Normally, the switching control circuit 2 of a switching power supply is controlled by a 1st output in accordance with the 1st threshold. If the output voltage is lowered instantaneously by sudden load fluctuations, etc., a series control circuit 3 of a series power supply is controlled by a 2nd output in by the 2nd threshold, which is set at a value than the 1st threshold and the output of the series power supply is combined with the output of the switching power supply, and the confined, output is supplied to a load 5.
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