Patent ID: 9276472
Filing Date: 2016-03-01
CPC Classification: G05F,H02M

Claim Text:
1. A DC/DC converter comprising: a switching circuit for driving a switching FET for increasing or decreasing voltage; and a switching circuit for driving a ringing frequency changing circuit, wherein one end of a capacitor is connected to a drain of the switching FET for increasing or decreasing voltage, the other end of the capacitor is connected to a drain of an FET for the ringing frequency changing circuit, a source of the FET for the ringing frequency changing circuit is connected to GND, and a control circuit is provided which makes the ringing frequency changing circuit valid so that a ringing frequency becomes low only in a ringing frequency component exerting large influence on deterioration in EMI in a ringing which occurs at a timing when the switching FET for increasing or decreasing voltage is turned on or at a timing when the switching FET for increasing or decreasing voltage is turned off, and which makes the ringing frequency changing circuit invalid at the other timings.