smps need help ... high ripples at the output

[jegandren]

smps need help ...

hi all,



I have designed a smps and it is working. schematic is as attached. but i have problems of high ripples at the output..



here i have noticed that when the switching transformer is switching the shape of the primary transformer wave has ripple.



could anyone suggest a method to have a clean switching .

 

[eem2am]

smps need help ...

sorry i cannot yet open your file.

but check the output caps ESR

is their enough output capacitance?

have you put snubbers on things?

have you reduced all current loops , especially power switch loop and rectifier loop.

smps eg flyback often resonate at the drain node..its normal and even some convetrers like TEA1507 use it for low voltage switching advantage.

 

[stabby21]

smps need help ...

I think you have a no load voltage. just try adding a pre load for your smps.

 

[darla1]

Re: smps need help ...

hey try to reduce ESR and use snubber for diodes if possible or add to MSOFETs

the ripple which you are showing is at low load or higher load?

darla