| 摘要 |
PROBLEM TO BE SOLVED: To prepare a small-sized charging pump type cascade DC-DC converter having a low internal resistance of performing various type voltage gains in a high efficiency. SOLUTION: Both electrodes of a charging pump capacitor CFLYK or the like of first or K-th (=2 to n) element stage of the converter can be connected to an input voltage VIN or an output from one of controllable switches SK1 to SK4. Additional controllable switches QK1 to QK(K-1) can be connected to an output or input voltage of a preceding stage of electrode of a charging pump capacitor of n-th (>=2) stage not connected to an output VOUT of the converter during a discharging phase of a charging pump cycle. A control circuit controls the switch SK1 for connecting the electrode of the n-th stage charging pump capacitor to outputs of an (n-1)-th stage and an additional controllable switch during a charging phase to connect an output or input voltage VIN of a preceding means to the electrode of the n-th capacitor having a maximum efficiency of the converter.
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