Different D+ line behavior for different batches of NRF52840

[Sreejit]

Hello everyone.

We have a design based on NRF52840, which uses the built in USB peripheral and was fully tested and prototyped using NRF52840-QIAAD0-2031MR. We have now manufactured ~50 boards and the IC assembled on it is NRF52840-QIAAAA-1716AK. Even though all the other peripherals are working correctly, the USB is not enumerating. The D+ line does not get pulled high when the USB cable is connected as it was happening with the prototype board.

I was wondering if there are any errata or any other pointers for troubleshooting this issue.

Regards,

Sreejit

[Kenneth]

Hi,

I am not sure which nRF5 SDK you are working with, but the latest is nRF5 SDK v17, you may try to program one of the latest USBD examples from there for comparison. This should include the latest errata workarounds, but you may also find a description here of current errata's:
https://infocenter.nordicsemi.com/topic/errata_nRF52840_Rev1/ERR/nRF52840/Rev1/latest/err_840_new.html 

If the problem persists, you may need to create a new case for someone to review your schematic and layout.

Kenneth

[Sreejit]

Thanks for the reply. I am working with nRF5 SDK v16. I'll give v17 a go.

[Sreejit]

Hi Kenneth,

Same results with v17. The usb works on replacing the IC with a newer date code.

[Kenneth]

What was the new and old date code on the ic's? Can it been any electrical shorts?

Best regards,
Kenneth