日本語
Hey guys,
On a PCB i'm making I really want to get MCU VCC to the other side of the MCU for the reset pullup, but the layers and layout is very constrained.
I'm thinking about routing the VCC trace through an unused i/o pin on the MCU and it got me thinking about the general issues that might cause.
The only three i can think of are
- Depending on layout, current draw in the trace, and trace resistance it maybe possible that the i/o pin voltage could be higher than the voltage at the VCC pin.
This could cause power to backfeed into the i/o pin with unpredictable results.
(In my circuit this can't happen, as power goes to VCC first, then off through the i/o to the reset pullup resistor)
- Accidentally coding the MCU to set that i/o pin to output low, which would short it out.
- Bad practice. (or is it?)
Can anyone think of others?
- Comments(1)
A****min
Jun 05.2019, 19:51:13
One thing I have seen people do is leave the soldermask over the pad of the pin, thus isolating the pin from the pad. Depending on your application this might be a usable solution (dependent on vibration, etc.)
If the pin 100% will never need to be used could you break it off?
