| 摘要 |
PROBLEM TO BE SOLVED: To appropriately cancel soft-start control after start of operation, without having to separately provide a component dedicated to current detection. SOLUTION: A control unit for DC-DC converters is provided with first and second MOSFETs 22, 24 connected to a coil 18 provided between charging/discharging means 12, 14. Current, flowing in the forward direction in a body diode 28, formed between the source and the drain of the second MOSFET 24, is detected. In steady-state operation, synchronous rectification control is carried out to cause the MOSFETs 22, 24 to perform inversion operation, relative to each other and supply direct-current power from the charging/discharging means 12 to the charging/discharging means 14. When operation is started, soft-start control is carried out, while gradually increase the on-duty period of the first MOSFET 22 and the second MOSFET 24 is turned off. When the current is continuously zero or is higher during the off-duty period of the first MOSFET 22 in soft-start control, the soft-start control is canceled or terminated, and synchronous rectification control is started. COPYRIGHT: (C)2007,JPO&INPIT
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