| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To protect a synchronous rectifier against increase in an input voltage for sure and also, for that protection, avoid increase in a regenerative current when the power supply stops. <P>SOLUTION: There is included in a switching power supply using a synchronous rectification type flyback converter a synchronous rectification drive circuit 30 which blocks supply to the gate of a synchronous rectification FET 24 of a drive signal generated from a negative polarity induction voltage which develops in a drive coil 18 of an output transformer 12 when a switching FET 20 is turned off, and also reduces a drive signal generated from a positive polarity induction voltage which develops in the drive coil 18 when the switching FET 20 is turned off due to stoppage of the power supply and then, after a prescribed time, turns the synchronous rectification FET 24 off. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
