| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To achieve a secure overcurrent protective operation at a low cost in a switching power supply 11 having a plurality of pairs of secondary side circuits. <P>SOLUTION: In constitution which is provided with an output amount detecting circuit 16 which detects current capacity of a switching element Q and performs overcurrent protective operation and a switching control circuit 15, an output voltage detecting circuit 17 for detecting output voltage Vo2 of a load L2 side of high voltage and high output, and a shortage element 18 which short-circuits between terminals in false when the detection voltage becomes at least a constant value, are arranged. As a result, when the shortage element 18 short-circuits, load of a secondary side is increased, and output of a load L1 side of low voltage and low output can be restrained by excess current protective operation. Hence, by using not complex constitution wherein current detecting circuits are arranged individually on the respective outputs of a secondary side and stopping and control of output are performed individually based on current detected values, but cross regulation, simple and a secure overcurrent protective operation can be realized with simple constitution. <P>COPYRIGHT: (C)2004,JPO</p> |
