Soft finish inductor for TOPswiotch flyback?
Posted by: treez
on
Hi,
Page 18 of the TOP264-271 datasheet says L2 is for soft finish.
However, do you agree, it is not?
L2 is an output LC filter to reduce the ripple on the vout.?
Use of L2 does not mean getting rid of capacitors, as the datasheet says, would you agree?
Comments
Thanks, ayk, if it were for soft finish, it would have a minimum value requirement....i have never seen a min value for one of these inductors, in this place.
Hi,
Yes, you are right that L2 acts as an additional LC filter for the output, but during start up it acts as a soft finish inductor for the feedback network by limiting the risetime of the output to prevent the possibility of an overshoot.
L2 is not intended to eliminate any filter capacitor in the output, instead the datasheet is saying that L2 can replace the typical soft finish cap that is placed across the reference (U3).