Hi, I am having a similar request.
Actually I do not need all schematics and details. I am looking for what pins are used for the connection with the Pi.
As a lot of other people noticed the pHAT is not very accurate with the temperature. My idea is to connect the Pi and the pHAT with some jumper-cables. I do not have 40 and I do not want to just try and guess.
So far I did not learn a lot from all the documentation, or I just did not find the right one yet.
Any chance that you could point me/us in the right direction?