| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device which avoids a reception failure of AM radio broadcasting caused by a power supply noise and attains power supply noise reduction.SOLUTION: An order n (n is a natural number) of a harmonic component accompanying switching operation in a power supply device, close to a reception frequency fc of AM radio broadcasting is calculated, and it is determined whether the harmonic component of the order n is higher or lower than the reception frequency fc of the AM radio broadcasting. In accordance with a result of the determination, an upper limit and a lower limit of a power supply frequency fs which does not interfere the reception frequency fc of the AM radio broadcasting are determined from an original power supply frequency fso of switching, the order n of the harmonic component, the AM radio reception frequency fc and a bandwidth BW of AM radio reception, and a power supply frequency fs is set within a range specified by the upper limit and the lower limit. |
