Patent Number: 8,791,748

Title: Charge pump circuit and operation control method thereof

Abstract: 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, includes: a voltage conversion circuit having a flying capacitor, a step-down output capacitor, a step-up output capacitor, 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 connection states 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 depending on each signal outputted from the output voltage detection circuit unit.

Inventors: Nishida; Junji (Neyagawa, JP)

Assignee: Ricoh Company, Ltd.

International Classification: G05F 1/10 (20060101); G05F 3/02 (20060101); H02M 3/18 (20060101); H02M 7/00 (20060101)

Expiration Date: 7/29/12018