Overcurrent protection circuit for switching power supply

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