| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that it is difficult to maintain the reliability of a switching element, regardless of the fluctuation of an input voltage. SOLUTION: The switching element of a DC-DC converter is controlled by duty ratio control. This duty ratio (a Duty value D) is set, in principle, according to a manipulation variable (a base value Dfb) of feedback control, in which an output voltage Vout is used as a control variable in a feedback control section B10. Taking into consideration, however, that a voltage supplied between the input and output terminals of the switching element depends on the input voltage Vin of the DC-DC converter and the Duty value D, guard processing is performed with a first guard value Dg1, determined according to the input voltage Vin and a second guard value Dg2, determined according to a variable amountΔVin of the input voltage Vin. COPYRIGHT: (C)2009,JPO&INPIT
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