I'm working with the STUSB4500 for USB PD Sink. My PD circuit is the same as the Sparkfun Power Delivery USB-C board, and everything works well, except for the fact that the ground is super sensitive and if anything connected to it bounces a little (probes for example) the circuit stops working. I also have the Sparkfun board and the same issue happens, I remember there was an instruction somewhere to connect the multimeter probes before plugging the USB cable to avoid this issue.
In my application I also have audio sockets, so every time I connect the audio cable the circuit stops working, so I need to find a solution.
The Sparkfun circuit is essentially this, with the addition of diodes for ESD protection and LEDs:
Source: https://cdn.sparkfun.com/assets/9/2/6/8/6/SparkFun_PowerDeliveryBoardSchematic.pdf
This is the same as the minimum implementation on the STUSB4500 datasheet (fig. 9 p.25):
https://www.st.com/resource/en/datasheet/stusb4500.pdf
On page 26, fig. 10 shows the typical application and the main difference is the addition of a MOSFET, T4. The reason for this MOSFET has been asked before in this question:
What this mosfet really needed on the STUSB4500?
The answer given was: "MOSFET T4 is to ensure the cold socket, preventing incoming negative voltage on VBUS"
Is this related to the issue I'm seeing, or is this happening for another reason? How can I fix this?
Any help will be very much appreciated!
