| 摘要 |
PROBLEM TO BE SOLVED: To provide a high efficiency power supply easy to handle and having high efficiency realized easily over a wide load range. SOLUTION: Each gate signal to main FET's 2 and 3 is shifted by a power supply controller 1 when the gate signal is generated as an output. A large low-speed FET 3 is switched while the small high-speed FET 2 is turned on. Then, a switching loss is not caused at the large FET 3, and there is only a small switching loss caused by the small FET 2 switched at high speed. Since the on-time of only the small FET 2 has a small ratio in all the on-time, an on-resistance loss can be reduced by means of low on-resistance of the large FET 3. In this way, the switching loss and the on-resistance loss can be reduced in a wide load range, and high efficiency can be realized.
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