| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly efficient switching power unit which has a precise overcurrent protective function, by removing power loss due to an output current detecting resistor. SOLUTION: This switching power unit comprises an error amplifier 16, an input current detecting circuit 3 which detects the current flowing to a switching element 4, and a pulse width modulation circuit 24 which determines the ON/OFF rate of the switching element 4, based on the output of the error amplifier 16 and the output of the input current detecting circuit 3, using frequency generated by a fundamental wave oscillator 21. Herein, an output 20 of the error amplifier is regulated with an input voltage compensating circuit 36 and an output voltage compensating circuit 31 whereby, since it does not use an output current detecting resistor, there is no power loss; and it can materialize a precise overcurrent protective function, thus providing a highly efficient switching power supply unit. COPYRIGHT: (C)2005,JPO&NCIPI
|
