Hi, for some reason I am not allowed to reply to the original one year old post about this topic. I am experiencing very similar issues with two HP ZBook computers.

Monitor: Dell U3818DW

Laptop 1: HP Zbook 15 G5 running Windows 10 Pro 20H2

Laptop 2: HP Zbook Fury 15 G7 Mobile workstation running Windows 10 Pro 21H1

USB C cable: Startech TBLT3MM2M

Symptoms: The screen connects ok at first. The battery icon changes to "plugged in". Most of the time the screen then loses connection after 1-5 seconds and the battery icon returns to "on battery". In some cases the connection will last for longer and I can work for maybe an hour or two before losing the connection again. Before finding the post from 3818owner I did not know if the problem was with the laptops or the monitor. Now I have started connecting the power adapter to my laptop and the system has been working stable since. I think I have found the culprit and it is the Dell monitor that is not handling the USB power delivery protocol properly. The official policy from Dell is:

"Dell Policy = A firmware update to the TPS6598E chip will not correct these issues. There will not be a power delivery controller chip upgrade replacement to correct this incompatibility issue. "

First off, there is no TI chip called TPS6598E. They are probably referring to one of the TPS6598X family of devices: TPS65981, TPS65982, TPS65983 etc. I glanced through this application note: https://www.ti.com/lit/pdf/slva842 At least this host device is supposed to send PS_RDY at some point in the negotiation process. I also found an application note about how to update firmware to the TPS65982 over I2C. It seems that the controller itself allows for updates(?).

Anyway: I just wanted to report that the problem is also present on HP laptops and is not only present on Apple laptops.

Thanks to the original poster for pointing me in the right direction!

 

BR,

Øyvin Eikeland