Patent ID: 7586294

Claim:
A method of performing a zero-current switching of an energizing switch in a current resonance type DC/DC converter, wherein said current resonance type DC/DC converter includes said energizing switch which is turned on/off in response to a driving control signal that is directly supplied to said energizing switch, a resonance inductor having an end connected to said energizing switch, and a resonance capacitor having an end connected to another end of said resonance inductor, said method comprising: detecting edges of the driving control signal being supplied to said energizing switch to produce a logic control signal; detecting edges of a particular voltage between said energizing switch and said resonance inductor to produce a logic voltage siginal; calculating an error amount between the driving control siginal being supplied to said energizing switch and the particular voltage between said energizing switch and said resonance inductor based on the logic control signal and the logic voltage signal; determining an off timing of said energizing switch based on the calculated error amount so as to reduce the error amount to produce a determined off timing; generating a new driving control signal based on the determined off timing which, when supplied to said energizing switch, will cause said energizing switch to turn off at a timing when a current flowing through said energizing switch substantially becomes zero; supplying the new driving control signal to said energizing switch; and repeating the foregoing steps to thereby form a feedback loop using the driving control signal and the particular voltage between said energizing switch and said resonance inductor.