Patent ID: 8791748

Claim:
A charge pump circuit which steps down an input voltage inputted from an input terminal and outputs it as a step-down output voltage from a step-down output terminal, and steps up the input voltage and outputs it as a step-up output voltage from a step-up output terminal, comprising: a voltage conversion circuit including: a flying capacitor which is charged with the input voltage; a step-down output capacitor which is connected between the step-down output terminal and ground; a step-up output capacitor which is connected between the step-up output terminal and ground; and a plurality of switches, wherein the flying capacitor, the step-down output capacitor, the step-up output capacitor, and the switches are connected, and the voltage conversion circuit is capable of switching a first connection state in which the flying capacitor is charged with the input voltage, a second connection state in which the step-down output capacitor is charged with the charged voltage in the flying capacitor, a third connection state in which the step-up output capacitor is charged with a voltage in which the input voltage is added to the charged voltage in the flying capacitor, and a fourth connection state in which the step-up output capacitor is charged with a voltage in which the charged voltage in the flying capacitor is added to the charged voltage in the step-down capacitor by switching each on/off state of the switches; an output voltage detection circuit unit which makes a comparison of a voltage between the step-down output voltage and a first predetermined voltage, and makes a comparison of a voltage between the step-up output voltage and a second predetermined voltage, and produces and outputs each signal indicating each result of the comparisons; and a control circuit unit which performs a switching control for switching between the first connection state, the second connection state, the third connection state, and the fourth connection state depending on each signal outputted from the output voltage detection circuit unit, wherein two clock cycles of a predetermined clock signal are taken as one state, and the one state is divided into four steps from first to fourth steps, and in the first two steps of the four steps, the control circuit unit controls the voltage conversion circuit to be only in the first connection state, and in the last two steps of the four steps, the control circuit unit controls the voltage conversion circuit to be in any one of the first to fourth connection states depending on each signal outputted from the output voltage detection circuit unit.