| 摘要 |
A DC-DC conversion switching power supply is provided, including a plurality of DC-DC converters connected in parallel. A three-times frequency waveform which is generated from a three-times frequency waveform generation circuit, and is in sync with an oscillation frequency of the DC-DC converters is superimposed on a control voltage which is compared with a switching current signal in a current mode control circuit for controlling the DC-DC converters, or a signal proportional to the switching current signal to control a switching current pulse. Since superimposing the three-times frequency waveform which falls over one period increases the control voltage decreased by switch-on noise of the other DC-DC converter, malfunction at a switch-on phase of the other DC-DC converter, caused by the decrease of the control pulse width, is prevented.
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