| 摘要 |
<p>Provided is a DC low-voltage power supply device having a high step-down efficiency by a piezoelectric transformer. The device includes: a drive circuit (110) having switching elements (131, 132) and a choke coil (117) and converting DC input voltage into AC voltage by operation of the switching elements (131, 132); a piezoelectric transformer (120) which is driven by input of the converted AC voltage and outputting AC voltage stepped down; and a synchronization rectification circuit (130) having switching elements (131, 132) and chalk coils (136, 137) and converting the output AC voltage into a DC voltage. The piezoelectric transformer (120) has an output impedance of a predetermined range decided by an output voltage of a piezoelectric transformer (120) required in accordance with a synchronization rectification function of a synchronization rectification circuit (130) according to a resistance of a load (140) and an output current of the piezoelectric transformer (120) derived from the power saving rule.</p> |
