| 摘要 |
PROBLEM TO BE SOLVED: To provide a step-down circuit that uses a piezoelectric transformer, which is able to realize a large step-down ratio by a single-plate piezoelectric transformer while reducing conversion efficiency.SOLUTION: A step-down circuit uses a transformer, to the primary side of which an input power source is connected and to the secondary side of which a load is connected in parallel and which outputs a voltage lower than an input voltage. The piezoelectric transformer is formed from a single plate piezoelectric transformer. On the secondary side of the piezoelectric transformer, an inductance Ls is provided in series with the load. The inductance Ls is obtained such that the resonance frequency of an inductance L1 and a capacitor C1 connected in series with each other to serve as an equivalent circuit for the piezoelectric transformer is equal to the resonance frequency of a capacitor C01 and the inductance Ls. |
