| 摘要 |
PROBLEM TO BE SOLVED: To provide a output control method and its device for a constant voltage of a switching power supply circuit, capable of controlling the constant voltage of the output voltage with high accuracy. SOLUTION: When the output voltage of a secondary output winding (2b) that attempts to control the constant voltage is set as V<SB>2bset</SB>, the number of windings of a primary winding (2a) as Np, the number of windings of the secondary output winding (2b) as Ns, the inductance of the secondary output winding (2b) as Ls, and an output time, when outputs appear to rectifying smoothing circuits (4, 13) within an oscillation cycle (T) as T2, Formula (1) is satisfied. When a current Ip<SB>set</SB>, that flows to the primary winding (2a), reaches a set current Ip<SB>set</SB>obtained from the formula, the on-control of an oscillation switch element (3) is stopped, then the output voltage at the cycle reaches a set V<SB>2bset</SB>, and by repeating these procedures, the output at the constant voltage can be controlled. COPYRIGHT: (C)2004,JPO&NCIPI
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