Part Number: LM5023
Tool/software:
Hi,
I have SMPS project given the diagram below
Previously I had a ripple problem at the output which was solved by moving R23 to pins 1 and 2 of the opto guided by Ulrich...
However, I have a noise problem in which "spikes" appear... and this gets worse as I add load (1.5A)...
I have a PI LC filter at the output, how can I resize it to cover this noise if the pi filter is not the solution, what is the best way to solve this?
Hello,
I would first check to make sure the noise is real with a differential probe across the output capacitor. If you don’t have a differential probe than you can use tip and barrel scope probe technique to measure. Also, will need a ferrite toroid to form a differential probe. Please see the diagram below for how to do tip and barrel scope probe measurements.
If you verify the noise is real, you could have switching noise propagating through your system. More than like this noise would be caused by switching noise. If this is the case you can reduce this noise/ringing with a snubber across the secondary rectifier. The following link will bring you to an application note that has a section on how to add a snubber across the output rectifier. It is covered on pages 10 through 13 of the application note. https://www.ti.com/lit/an/sluaac5/sluaac5.pdf
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Regards,
