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Can I leave some VDD / VSS pins unconnected?

Question asked by Zhang.Yale on Dec 28, 2015
Latest reply on Dec 29, 2015 by mich.lei
First, I'm aware from the electronics stack exchange that connecting all power supply pins is required for all practical purposes and that even if skipping some seems to work, there eventually could be subtle failures. 

But my home made circuit board is facing severe routing challenges since it only has 1 layer. I've already resorted to creating many circuitous routes to deal with the limitations of 2D routing. Just look at the maze of wires.

Although I'm amazed at how much you can do with just 1 layer, I still need to solder on ~5 jumpers. I'm tempted to reduce them by omitting some power supply connections. Probing the power pins on a STM32F4 Discovery board, it seems all the VSS and VDD pins are internally connected, so leaving some unconnected seems a possibility. I haven't checked for an unsoldered chip, which could prove otherwise.

Here are my circumstances:
1.  The MCU doesn't do any analog processing or analog I/O - only digital. It seems digital should be more robust against voltage variations (50mV max according to datasheet). I know the internal RC oscillator is powered by the analog supply, so leaving VddA/VssA unconnected is out of the question.

2. total current use is right around 100mA. According to the datasheet, even 1 pin can provide this amount of current.  There is 1 LED that blinks momentarily that could add ~20mA.

On the STM32F7 QFP 100 package I'm using, there's at least 1 pair of VDD/VSS on each of the 4 sides, which makes sense since that would ensure any part of the chip would be within a certain distance from a VDD/VSS pair.

On the edge with pins 26-50, there are 2 pairs of VDD/VSS, so it seems getting rid of 1 pair will do the least harm.

Has anyone else been in my situation and attempted this? Anyone want to advise against this or give a tentative approval?

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