-Please check the bulk and decoupling capacitors on VDD_IO and AVDD12_x pins from Table 3 in the Application Note https://www.cypress.com/file/140751/download.
-Please add a bulk capacitor of 1uF on VBUS on US port and 150uF on VBUS in the DS ports to maintain stable voltage under maximum load condition.
- When you saw PWR_EN pulsing initially, did you see the same behavior on VBUS on the downstream ports?
-Could you please connect the hub to a Windows host and check if the issue persists?
-Currently, is the PWR_EN staying high all the time while OVRCURR also stays high when measured on the hub pins? Please send us the screenshot of the waveforms if possible.
We actually have the design working.. We only had 2 boards with the issue.. We validated all 24 boards and all have successful link.
On the new revision boards we will be adding more caps as recommended, for now we increased the value of the cap as recommended.
Thank you for all your help and please consider this issue closed.
Thank you again!