drgeoff wrote: ↑
Wed Jul 17, 2019 11:01 pm
LTolledo wrote: ↑
Wed Jul 17, 2019 9:53 pm
my usual advice is to tap the fan's power to the incoming 5v line (prior to RPi4B's internal protection circuity, so that will be TP1 for +5v and TP7 for the GND), and not from the GPIO header 5v line.
Perusal of https://www.raspberrypi.org/documentati ... educed.pdf
will reveal to you that TP1 and the 5 volt pins of the GPIO header are electrically equivalent. Ditto for TP7 and ground pins of the GPIO header. There is no polyfuse, perfect diode or any other series protection and thus no "prior" or "after" distinction.
very true that the TP1 and GPIO header pin2 and pin 4 for the +5V are electrically equivalent.
as well as TP7 and pin 9 and other ground pins on the header
I did checked the schematic before suggesting the TP numbers, I always do before making my fan connections on all RPi boards.
my point for selection these TP is that since its very near the power-in port (USB-C) the required current for the fan is localized as close as possible to the power-in port, and need not travel throughout the board all the way to the GPIO header.
reduces the current load to the foil paths.