| 摘要 |
PROBLEM TO BE SOLVED: To prevent the malfunction of excessive current protection by detecting a voltage drop after a switching element is turned on without making an influence exerted upon characteristics of the switching element, in a switching power unit that performs the excessive current protection by the voltage drop due to a current flow to an on-resistor at the on-time of the switching element. SOLUTION: The power unit comprises: an on-detection means that uses a voltage between main terminals of a first switching element; a current detection means that uses the on-resistor during an on-period; and a control means that turns off the first switching element when the on-detection is not obtained after a delay period that is determined by a control signal impressed to a control terminal of the first switching element. By using the voltage between the main terminals of the first switching element, the excessive current protection is surely performed during only the on-period, thus the sure excessive current protection can be achieved. COPYRIGHT: (C)2003,JPO
|
