Pin45 usage on 44 QFN package

Go To Last Post
4 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi Guys,

Is the thermal pad (Pin 45?) on the ATMEGA32U4 44pin QFN packages floating?

I used it to join all my Vcc pins in my PCB design and it's starting to feel like this was a bad idea. When I power up my prototypes they start to drain a lot of current above about 3 volts.

I can't seem to find any reference about this pin/pad in the data sheets or anywhere on the interwebs. Should I have left it floating or tied to GND instead of Vcc?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Normally they are Ground.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Back to the drawing board.. Thanks for the tip.

EDIT: You'd think if it were internally tied to ground it would drain current at any voltage, i.e. a short circuit. Not just at around 3v and above, but if ground it should be, then I'll make the alterations. Cheers.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.