| 摘要 |
PROBLEM TO BE SOLVED: To design a switching power supply so that highly efficient operation is performed with a maximum load and voltage and current are stably outputted even if a load varies. SOLUTION: Commercial power is rectified by a diode bridge 3 and a capacitor 4 and supplied to a transformer L through terminals 5 and 6. One end of a primary coil L1 is connected with a terminal 5, and the other end thereof is connected with a switching element 7. One end of a feedback coil L3 is connected with the switching element 7, and the other end thereof is connected with the terminal 6. A negative feedback circuit 8 is placed between the switching element 7 and the terminal 6. A secondary coil L2 is provided with a rectification circuit comprising a diode 11 and a capacitor 12. The junction point between the coil L2 and the capacitor 12 is connected with a terminal 16 through a resistor 14. At a detection circuit 13, the voltage between terminals 15 and 16 is detected, and the current across the resistor 14 is detected. When the detected voltage and current are equal to predetermined values, a control signal is supplied to a feedback circuit 9. COPYRIGHT: (C)2003,JPO
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