| 摘要 |
PROBLEM TO BE SOLVED: To see that switching frequency does not approximate the used frequency of a device thereby mixing therein as noise, without dropping its frequency even when the load of a PWM system of DC-DC converter lightens. SOLUTION: Two or more candidate values for switching frequency are stored in a register 15, and a frequency directing part 16 selects one of those candidate values, based on the setting geared to the state of load, and sets it as the frequency of pulse oscillation in a PWM controller 13 for a switching power source 1. The PWM controller 13 performs pulse width modulation so as to suppress the error between the output voltage detected by an error detector 12 and the reference voltage, for the pulse signal generated by the pulse oscillation, and opens and closes the line of output to the load of the DC-DC converter 11 via a drive 14. COPYRIGHT: (C)2006,JPO&NCIPI
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