| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a DC-DC converter that can suppress power consumption. <P>SOLUTION: A DC-DC converter comprises: a control circuit; a switching element; and a constant-voltage generation part for generating an output voltage with the level suitable for the duty ratio of the switching element. The control circuit comprises: an AD converter for converting an input voltage and the output voltage from an analog value to a digital value; a signal processing circuit for determining the duty ratio using the digital value of the output voltage; a pulse modulating circuit for generating a signal that controls the switching of the switching element according to the duty ratio; and a power supply control circuit for selecting the presence or absence of the supply of the power supply voltage to the signal processing circuit according to the digital values of the input voltage and the output voltage. The signal processing circuit has a storage device for storing the duty ratio. The storage device includes a storage element, a capacitor element for storing data of the storage element, and a transistor for holding the charges of the capacitor element and including an oxide semiconductor in a channel formation region. <P>COPYRIGHT: (C)2013,JPO&INPIT |
