Voltage-change control circuit and method

Abstract

In a charge-pump booster circuit, the control clock is controlled on a small-step basis to thereby suppress the boost amplitude and the occurrence of various noises. Provided are a charge-pump booster circuit section for boosting an external power voltage in absolute value level, a boost-voltage feedback section for controlling the booster circuit section, and a clock buffer section. In the boost-voltage feedback section, an output level of the booster circuit section is detected by a voltage detecting section. This is compared with a reference level, and depending upon the comparison result, a count operation is made in an up/down counter section. Based on the count value, the control amount is shifted on a small-step basis from the D/A converter section, thereby controlling the power voltage of the clock buffer sectionthrough the level shifter section.