MP5475 NC Pins - Question about grounding

DC-DC Power Converters
1

Hello,

Can NC pins 1, 9, 19, and 26 be connected to PGND on this chip? Please let me know.

Regards,

Tony

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2

Hello Tony,

It’s best to keep these pins floating. What is your motivation to connect these pins to GND if I may ask?

Best,

Krishan

3

Hi Krishan,

I have no reason to connect them to GND. It was just a question to see if these pins could be grounded for thermal and/or electrical reasons. I’ll do as you said and float them.

Thank you,

Tony

4

Understood. Let me verify this with some colleagues to see if seeing if the NC pins can be in any way used to help with any thermals and extra electrical pad connections. You’ll hear an update from me soon.

Best,

Krishan

5

Hello, I spoke to a colleague who is involved in the design of the MP5475.

They confirmed that despite the recommendations to float the NC pins, they have no real connection to anything internal in the MP5475 IC. Given this, you should be ok to connect these pins to PGND to improve on thermals.

Best,

Krishan

6

Thanks for the update.

.

NC pins should generally be left floating unless the datasheet explicitly states otherwise. Tying them to ground can introduce unwanted coupling or thermal issues. This principle applies broadly, even in power designs using devices like the FSCQ1565RT. Always follow the manufacturer’s layout recommendations to avoid subtle stability or EMI problems later on.

7

Hi Krishan,

Thanks. I’ll connect these pins to PGND.

Best Regards,

Tony

8

Glad I could help, since the subject matter of this post is now fully addressed, I will now close this post.

Best,

Krishan