VEHICLE-MOUNTED STEP-DOWN SWITCHING POWER SOURCE, VEHICLE-MOUNTED ELECTRONIC CONTROL DEVICE, AND IDLING STOP SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide stable output while suppressing noise from a harmful frequency band even when input voltage drops.SOLUTION: A vehicle-mounted step-down switching power source includes switching frequency control means; and the switching frequency control means includes a switching frequency range setting unit that changes a switching frequency within a range between fa and fb, and a switching frequency routing unit that passes a frequency fc in the middle of the fa and the fb, and skips a frequency band from fd to fe that is present between the fa and the fb.