| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC conversion circuit with high reliability.SOLUTION: A DC conversion circuit includes: an inducting element for generating electromotive force in accordance with change in current flowing therein; a transistor including a gate, a source, and a drain, and setting a turned on state or a turned off state to control generation of the electromotive force in the inducting element; a rectifying element that is made conductive when the transistor is the off state; and a control circuit for controlling the turned on state or the turned off state of the transistor. The transistor includes an oxide semiconductor layer having hydrogen concentration that is equal to or less than 5×10atoms/cmas a channel formation layer. |
