Patent ID: 7187159

Claim:
A DC—DC converter of a charge pump type, comprising: a constant voltage circuit part configured to convert an input voltage into a first voltage and output the first voltage from a first output terminal; a charge pump circuit part configured to convert the first voltage input from the constant voltage circuit part into a second voltage and output the second voltage from a second output terminal; a current detection circuit part configured to convert an output current of the constant voltage circuit part into a third voltage and output the third voltage; a first output voltage detection circuit part configured to detect the first voltage at the first output terminal and generate and output a first detection voltage proportional to the detected first voltage; a first overcurrent protection circuit part configured to compare the output third voltage and the output first detection voltage and reduce the output first voltage and the output current of the constant voltage circuit part when the output third voltage is higher than the output first detection voltage; a second output voltage detection circuit part configured to detect the output second voltage of the charge pump circuit part and generate and output a second detection voltage proportional to the detected second voltage; and a second overcurrent protection circuit part configured to compare the output third voltage and the output second detection voltage and reduce the output first voltage and the output current of the constant voltage circuit part when the output third voltage is higher than the output second detection voltage.