POWER SUPPLY VOLTAGE CONVERTING CIRCUIT, ITS CONTROLLING METHOD, DISPLAY, AND PORTABLE TERMINAL

摘要

PROBLEM TO BE SOLVED: To solve the problem that the circuit size increases when the gate voltage of a transistor for driving a flying capacitor is controlled with a voltage amplitude being controlled by an input voltage because the transistor size increases when a high current capacity is realized. SOLUTION: In a charge pump type DC-DC converter 10 for converting a power supply voltage VDD1 into a power supply voltage VDD2, a control pulse of VSS-VDD1 amplitude is subjected to amplitude conversion to produce a control pulse of VSS-VDD2 amplitude by a level shifter 12. The flying capacitor C11 is then driven to charge/discharge by MOS transistors Qp11 and Qn11 in a charge pump circuit 11 using the control pulse subjected to amplitude conversion as a pumping pulse and MOS transistors Qn12 and Qp12 on the output side of the flying capacitor C11 is subjected to switching control. COPYRIGHT: (C)2005,JPO&NCIPI