Buffer for RGMII

Allan Fan

Expert 5730 points

Other Parts Discussed in Thread: SN74AXC8T245

Hi Expert,

Do we have buffer for RGMII supporting >125Mhz? Customer try to improve Tfall within 750ps cause it failed.

Measured Tf=844 ps

Thanks,

Allan

over 3 years ago

0 Chad Crosby over 3 years ago

TI__Expert 6680 points

Hi Allan,

See the following FAQ: https://e2e.ti.com/support/logic/f/151/t/740319

Thanks!

Chad Crosby

0 Allan Fan over 3 years ago in reply to Chad Crosby

TI__Expert 5730 points

Hi Chad,

Customer is concerning fall time not the signal level. Can level shift improve the fall time issue?

Regards,

Allan

0 Clemens Ladisch over 3 years ago in reply to Allan Fan

Guru 244020 points

It would be possible to use a level shifter as buffer, but you could just as well use a plain buffer.

For supply voltages up to 2.5 V, the AUC family would have the fastest output drivers. For 3.3 V, the fastest family is LVC. Which buffers or transceiver to use depends on the number of channels in each direction.

0 Chad Crosby over 3 years ago in reply to Allan Fan

TI__Expert 6680 points

Hi Allan,

To follow up to Clemens's post, He's correct: The fastest buffers we offer for 3.3V is the LVC family; however, these devices may not be fast enough to support RGMII speeds. The reason I suggested the above FAQ is that we offer a level shifter that is rated to support RGMII, that could be used as a buffer if both supplies are the same voltage.

If you have any questions, please let me know.

Thanks!

Chad Crosby

0 Allan Fan over 3 years ago in reply to Chad Crosby

TI__Expert 5730 points

Hi Chad, Clemens,

Thanks for the feedback. We proposed SN74AXC8T245 and will let you know if further questions.

Regards,

Allan

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Buffer for RGMII