| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED drive device, and an illuminating fixture and a vehicle illuminating device, capable of suppressing change in output caused by rapid change in power supply voltage even in a case that a characteristic of on-duty to the power supply voltage is different by variation in forward voltage of an LED.SOLUTION: A duty command value setting part 15 sets a duty command value of a switching element Q1 depending on a difference between a detection value of a load current and a current command value. A second setting part 17 sets a maximum duty curve and a minimum duty curve respectively prescribing a maximum value and a minimum value of the on-duty to power supply voltage by using the power supply voltage, the duty command value, and a voltage-duty curve that is set to the first setting part 16. A duty restriction part 18 restricts the duty command value to the on-duty calculated from the maximum duty curve or the minimum duty curve on the basis of the power supply voltage, when the duty command value becomes higher than the maximum duty curve or lower than the minimum duty curve by fluctuation in the power supply voltage. |
