Mk II PCB

I've been working my way up to a Mk II PCB for a few weeks now and I think it's getting close to time to press the Go! button. There are three principal drivers:

1. The decision to use an INA253 current sensor instead of the Hall effect device that the Mk I used.
2. To make improvements to the RF immunity, now that I know that RF just gets everywhere!
3. To fix various errors in the Mk I design.

The most experimental aspect of this new PCB is the use of an INA253 current sensor. This is a surface mount device and it's the first time I have designed a PCB using SMDs, so that should be interesting. I have discussed this already a few posts back but the fact is that I won't know whether it's a good idea and, importantly, that RF isn't getting into it, until I can test the Mk II board. Fingers crossed!

I've added quite a lot of decoupling to try to keep RF out of places it has no business being. The new PCB design aims to keep this decoupling as close to the SBC input pins as possible, again to frustrate illicit RF ingress. We know that RF is a black art, especially at 150MHz, so again, only testing will reveal the success of otherwise of this strategy.

And, of course, there are the inevitable design errors to fix. As careful as I might be, the Mk I PCB for all my projects always seems to have a few.

The proposed Mk II circuit diagram

The proposed Mk II PCB