I'm building an isolated USB hub with the TI TUSB2036 and the AD ADuM4160, which isolates the upstream port.
Problem: The hub isn't recognized. When removing the ADuM4160 and connecting the upstream port directly the hub is enumerated. This shows me that the basic hub circuitry is working. Clock, Reset and voltages are correct.
The AD isolator chip is supposed to be transparent to the USB protocol. The 1k5 pullup on DP0 is integrated into the isolator chip and controlled through pin 12 (PIN, high=pullup active), so it is not drawn in the schematics. I failed to find a suitable alternative to the AD chip from TI.
Any suggestions? I'm completely open to alternative chip solutions.
I think your problem is the connection of ADUM's PIN terminal, it should be connected to 3.3V and remove the R105. Also, the terminal DP0 of the hub should be connected as well to DP0PUR. DP0PUR should not be connected to PIN, since it is already internally connected in the hub.
Problem solved. The ADuM does not replace the 1k5 pullup. PIN only controls whether a detected pull-up is signalled to the other side.
Thanks for your input.
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