STEP-UP/STEP-DOWN POWER CONTROLLER AND METHOD OF CONTROLLING STEP-UP/STEP-DOWN POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To provide a voltage step-up/step-down power controller reducing power consumption by optimizing a voltage conversion operation between I/O voltages to suppress an unnecessary voltage conversion operation in variations of an input voltage VIN.;SOLUTION: The voltage step-up/step-down power controller has: a step-up section for inputting an input voltage and outputting a step-up voltage; and a voltage step-down section for inputting the step-up voltage and outputting the output voltage by stepping down the step-up voltage via a first transistor. The step-up section outputs a step-up voltage higher than the output voltage when the input voltage is lower than a first reference voltage higher than the output voltage, and outputs the step-up voltage equal to the input voltage when the input voltage is higher than the first reference voltage. The step-down section controls on resistance in a unsaturated region of the first transistor when the input voltage is higher than a second reference voltage lower than the output voltage. When the input voltage is lower than the second reference voltage, the first transistor is used in a saturated region.;COPYRIGHT: (C)2010,JPO&INPIT