| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply unit for suppressing the variations in the output voltage by making a start-up time constant irrespective of a power supply voltage. SOLUTION: The power supply unit 10, configured as a switching power supply unit detects an input voltage value at the start of voltage transformation, increases the inter-terminal voltage of capacitance at a predetermined ratio, on the basis of the detected input voltage value so that the time required to get a target voltage value becomes constant; generates a drive control signal equivalent to an on-duty upper limit value based on the inter-terminal voltage; and outputs the signal generated to a switching element. COPYRIGHT: (C)2011,JPO&INPIT
|
