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While trying to fix a laptop, I was de-soldering a TPS51125. I added a bit too much solder to the power pad while wicking so I had the "smart" idea to use a solder pump to remove it... but the pad came with it!

I've learnt a lesson but I'm wondering if this pad is really necessary for normal functioning? Can I go without it or does it need to be connected for electronic and/or thermal reasons?

If I just stick the pad back on the pcb and solder the IC back, will it not being connected do anything to affect it's ability to function?

EDIT: here's an image of the problem for interest sake missing IC power pad

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    \$\begingroup\$ Can you add a picture ? \$\endgroup\$ – Damien Oct 9 '18 at 8:58
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    \$\begingroup\$ I want to but I'm at work. Can only do so in about 8 hours. \$\endgroup\$ – Daniel Oct 9 '18 at 9:01
  • \$\begingroup\$ Added image a bit late but may help others who arrive here (sorry for bad quality) \$\endgroup\$ – Daniel Oct 9 '18 at 22:41
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It might be risky.

The chip uses the power pad as a ground pad, it has another pin for ground as well, but it is likely the chip is designed to have most of the current going through the power pad.

Beside heating issue (which might be fixed by adding a cooling to the top of the chip), the fact the chip might have improper grounding can create issue.

One of this issue can be improper regulation of the output voltage and in the worst case, generating a higher voltage than it should be and in turn can destroy further components.

A safest solution to fix this issue would be to order a step-down converter small enough so you can fit inside the laptop and with the appropriate voltage and current ratings. Find on the board some locations where you can connect the input, output and ground with some wires.

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  • \$\begingroup\$ hmm. Since it's an old laptop, I don't have much too lose at least. It's more of an experiment to see if I can fix it at this point. That's an interesting solution I never thought of. \$\endgroup\$ – Daniel Oct 9 '18 at 9:05
  • \$\begingroup\$ I forgot to mention, if you go for this solution, don't forget to remove the 2 mosfets of the broken chip, as their gate will not be connected, they might float and start switching randomly. \$\endgroup\$ – Damien Oct 10 '18 at 3:25
  • \$\begingroup\$ Yeah I'm starting to think this will be too complex for me as a hobbyist. But will hopefully be useful to others. Thanks \$\endgroup\$ – Daniel Oct 10 '18 at 8:53

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