ECMF02-2AMX6 Bad Eye Diagram for USB2.0

[CBmn]

Hi,

we are using the ECMF02-2AMX6 in our USB 2.0 lanes. The traces on our board are quite short. However, the measured eye diagram of USB 2.0 was not good. The eye is very close to the limit especially at the rising part. Now I saw that in the datasheet of the ECMF02-2AMX6 the eye diagram looks quite similar to ours. Would you confirm that the filter is likely the cause?If yes, are there any recommendations how to avoid this or get better signal integrity? Any filter type that has better signal integrity?

Regards,

Carmen

[FGUIT · Accepted solution]

Dear Carmen,

Thanks for using ST ECMF02-2AMX6 on your design.

You’re right, the eye diagram you measured is close to the one on the ECMF02-2AMX6 datasheet : it is compliant with USB 2.0 requirements eye diagram template.

However, if you want more margin on eye diagram, I suggest you to use ECMF02-2HSMX6: below datasheet eye diagram for USB 2.0.

 

To perform tests, ECMF02-2HSMX6 can be mounted on the same footprint as ECMF02-2AMX6, but for finale PCB, footprint needs to be updated with the one on ECMF02-2HSMX6 datasheet.

Also, pay attention to connect D+/D- connector pins to the connector, and D+/D- IC pins to IC : this is to place ESD protections on the connector side. D+ and D- can be swapped, D+ and D- lines are identical.

Best regards.

Fabrice.

[CBmn]

Hi Fabrice,

thank you for your response!

We will do some measurements with your suggested alternative and hopefully the eye will look better.

Best regards,

Carmen