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TMUX6219-Q1: Multiplexing 100M ethernet

ahmet selcuk silindir
Prodigy 160 points
Part Number: TMUX6219-Q1
Other Parts Discussed in Thread: TMUX6219, TMUX7234, TMUX4052, TMUX7436F

Hi,

In my project, I need to multiplex high voltage interfaces with 100 base ethernet and I was planning to use TMUX6219 for that purpose. S1 inputs of the multiplexers will be connected to ethernet MDI signals and S2 inputs will be connected to high voltage busses(12V-24V), multiplexers will be powered from 28V and D outputs will be connected to the connector. I want to be able to select either 100M ethernet or other interface to use on the connector. Can I use TMUX6219 for that or would you suggest something else?

Kind regards,

Ahmet

  • 0
    TI__Prodigy 420 points

    Hi Ahmet,

    What base is your ethernet running at? There are various different variants for the ethernet to run at, where depending on your base the TMUX6219 might not be able to sustain the 100M data rate. Additionally, we'll also need to know what current you'll be running through the high voltage bus (S2) as well.

    Below you can find some examples of what types of base variants your ethernet signal might be using.

    Fast Ethernet - Wikipedia

    Also please let us know if you will be utilizing the negative signal (for twisted pairs) in your application as well.

    Regards

  • 0 in reply to Santiago Fonseca
    Prodigy 160 points

    Hı Santıago,

    Thank you for your response. The ethernet will be running 100 Base T1 for automotive ethernet. Basically, it will be used for "doip" ethernet and high voltage side actually is not not always a communıcation bus but also some high voltage sıgnals wıll pass through on S2. The current on the high voltage side will not exceed 150mA. Negative signals are not utilized. I already have a prototype of this circuit and it runs at 10 Base only. 

    Regards

  • 0 in reply to ahmet selcuk silindir
    Prodigy 160 points

    Hi Santiago,

    I believe 100 Base TX would not be possible with this multiplexer but could you propose another multiplexer which can replace TMUX6219 even for 100 Base TX? What I wish is the same multiplexer with a higher bandwidth. Same operating voltage level, same on resistance, same footprint, same current capacity but a higher bandwidth. Probably it is impossible but different footprint is also acceptable :) 

    Regards

  • +1 in reply to ahmet selcuk silindir
    TI__Prodigy 420 points

    Hi Ahmet,

    You are correct in assessing that the TMUX6219 would not be compatible with a 100 Base TX ethernet signal, we would need a higher bandwidth alternative. To meet this requirement and still accommodate for the high voltage busses, I would recommend the TMUX7234. This option is our highest bandwidth multiplexer that can sustain the 150mA current on the high voltage side, while providing enough bandwidth for 100 Base TX ethernet and maintaining similar operating specs.

    We also have other higher bandwidth alternatives, but they'll only allow for a maximum input current of 125mA for your high voltage application.

    Regards,

    Santiago

  • 0 in reply to ahmet selcuk silindir
    TI__Prodigy 420 points

    Hi Ahmet,

    Upon checking it seems that we do not currently have an automotive counterpart available for the TMUX7234 (that is, no TMUX7234-Q1), only the base model. Would this be acceptable for your circuit? If not, I can look and see what else we can recommend for your application.

    Regards

  • 0 in reply to Santiago Fonseca
    Prodigy 160 points

    Hi Santiago,

    Thank you for your suggestion. This seems to be a good solution but can you also share other alternatives even if they have lower current capacity?

    With TMUX7234, I can replace 4 of TMUX6219. D1 will be the output/input on the connector side, S1A will be connected to ethernet MDI and S1B will be connected to other signal which can come be output of another TMUX analog multiplexer. They will be cascaded but the power off protection diode will be on the D1 of TMUX7234 since it is the last multiplexer before the connector. Do you see any issues in that usage?

    Regards

  • +1 in reply to ahmet selcuk silindir
    TI__Intellectual 1126 points

    Hi Ahmet,

    The only lower current capacity 24V 2:1 (SPDT) option we have is the TMUX4052 but this is much lower, only at 10mA. And likely would not work for you. 

    I don't see any issue with the logic of your setup. But if power off protection is needed you might want to look at the TMUX7436F.

    Additionally please keep in mind that cascading multiplexers can have negative impact to the signal. When switches are connected in series their capacitance add together which may reduce the bandwidth. This can be minimized by following High-Speed Interface Layout Guidelines but just something to be aware of. 

  • 0 in reply to Stephen Scheramic
    Prodigy 160 points

    Hi Santiago,

    Thanks a lot for your support. I think I received enough information to solve my issue. I will probably use your first suggestion which is more cost effective. 

    Regards