Question
I redesign a board, In that board I used the ADM3053. In previous version of
this board I have problems related with EMI (the board is out of Class B
Limits). I have a limited space for ADM3053 layout. With this space I only have
39pf for Stitching Capacitance. Waht can I do to improve the capacitance
without change the layout size?
Answer
We have guidelines on this topic, we rely on the attached application note
AN-0971 and the ADM3053 datasheet guidelines on PCB layout/capacitor placement.
For a small PCB area, the most relevant method of implementing the stitching
capacitance is the gap overlap method described on page 7 of AN-0971. It’s
possible to repeatedly overlap planes if multiple board layers are possible
(e.g. even 6, 8, 12 layers).
You mentioned you are out of Class B limits. Do you have any test results you
could share in order for us to understand how much emissions need to be reduced
in your application, and at what frequencies?
If you can share your layout this would also allow us to comment on any aspects
of it that can be improved.