Hi ,
One of my customer is working on Automotive design for which they are working on LM5118. LM5118 is working ok as per specification & no issue with electrical specification. They are now planning for EMI/EMC test & during pre scan LM5118 was failed. When they bypassed LM5118 whole unit passed with comfortable margin.
LM5118 is used as buck boost for 12V to 12V/2A output requirement. We have reviewed the layout & it is not the best one or we can say there is a scope for improvement. We have shared our inputs for the placement & layout.
When we probe the switching node with active probe(ground lead is not short but not long also) we observed 60MHz ringing. We also tried with EVM & that is also showing the same with lesser amplitude.
We suggested to keep provision for pre & post LC filter in present schematic with ceramic close to switching elements.
Can you guys help with your expert comments, so we can share with customer? We also observed that after adding the 5 Ohms of gate drive resistance ringing amplitue came down.
If anybody has observed the same, can you help with the suggestions.
Regards,
Mitesh