| 摘要 |
In an overcurrent protection circuit for a switching power supply having multiple voltage supply sections, an overcurrent in a low voltage supply section is detected to make it possible to take a countermeasure against overload in a transformer winding, using a simple and low cost circuit design. The circuit comprises: a current detection resistor 33 to detect a current in secondary side of the transformer; transistors 53 and 52 to be turned on by the current detection; a photocoupler 50 to be turned on and off by the transistors; and a switching power supply controller 7 to control on-duty of a power MOSFET 6 for removing the overcurrent. The current detection resistor 33 is provided in the line of a secondary winding 30 so as to be able to individually limit a current flowing through the secondary winding 30.
|
