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TMUX1574: Need recommendation to multiplex between 8 sd cards.

Cho
Prodigy 80 points
Part Number: TMUX1574
Other Parts Discussed in Thread: SN74CBTLV3251, SN74CB3Q3251, TMUX1308, TMUX1309, TMUX1575, SN74CBT16232, TMUX646

I can multiplex between 8 sd cards using 4 TMUX1574 but I would like to reduce the number of IC. I want to use 1 IC to switch between 8 SD cards. Can you recommend an IC that has similar specs to the TMUX1574 but can handle 8 sd cards?

The multiplexed need to be able to handle enough current for the VCC & IO lines as well.

  • 0
    Guru 272400 points

    Use 8:1 switches like the SN74CBTLV3251 or SN74CB3Q3251; they have a single channel, so you need multiple devices.

  • 0 in reply to Clemens Ladisch
    Prodigy 80 points

    Does a 4 channel 1:8 mux exist? I want to reduce the amount of IC's on the board and also cost per chip. Using a SN74CBTLV3251 or SN74CB3Q3251 would still require 4 chips and added cost. If not, it's actually more expensive to use the SN74xx.

  • 0 in reply to Cho
    Guru 272400 points

    There are no such large switches; you always need to combine multiple ICs.

    The TMUX1308 or TMUX1309 would still require four chips, but are cheaper.

  • 0 in reply to Clemens Ladisch
    TI__Genius 14350 points

    Hello Cho!,

    Looking into this some more I don't think we have an 8:1 4channel mux for you to use in this application and actually using the 4 TMUX1574 might be your best solution.

    Is board space a problem for you in this application and could you please let me know if using the tmux1574 4x is not a suitable solution for you?

    Regards,

    Kameron

  • 0 in reply to Kameron Hill
    Prodigy 80 points

    Hi Kameron! That's unfortunate, I want to clear up board space, clean the routing up and avoid the amount of IC's being used while reducing cost of production.

  • 0 in reply to Cho
    TI__Genius 14350 points

    Hello Cho,

    Ok understood! Sorry I forgot to mention this part

    So would the TMUX1575 be an option for you?  The TMUX1575 is an  alternate of TMUX1574 with inverted logic control, available in WCSP package(60% smaller than UQFN Package). I believe this device might be slightly more expensive 1ku but could help clear your board space. Also if pricing is a concern please feel free to contact TI sales representative so that they can help you with pricing.

    Please let me know what you think!

    Regards,

    Kameron

  • 0 in reply to Kameron Hill
    Prodigy 80 points

    Hi Kameron, thanks for the fast reply. It's not so much the footprint size that's the problem its the amount of traces that take over the board because running 4 chips to 8 devices. It starts to become a 4 layer board and I'd like to keep it under two.

  • 0 in reply to Cho
    TI__Genius 14350 points

    Hello Cho,

    Thank you for your reply!

    From my understanding looking into the mux portfolio some more I found 3 solutions that can solve your problem. 

    1. First because the TMUX1574  ( which is a 2:1 4channel) can support 2 sim cards ,  to support all 8 sim cards  you would need a  2:1 16 channel device  which is why I suggest the SN74CBT16232.  It's power supply range is from 4v to 5.5v which is a lower range than the tmux1574. In addition it doesn't have integrated protection features like fail safe logic and power off protection. Finally this device doesn't have 1.8v logic support so it will take a minimum voltage of 2v to send a high signal to the mux select pins. But depending on what signals you are passing and what voltage you are using to supply this device this could work in your application. 

    2.The next best option is using a 2:1 8channel device because it would be able to support 4 sim cards. While we don't have a direct 2:1 8 channel we do have a 2:1 10 channel that can do the same thing. This device is the TMUX646. So if you went with this solution you would need 2x/. This device is similar to the TMUX1574 in the fact it has 1.8v logic support and power off protection. It also has a wide supply range form 1.5v to 5.5v.

    Here is a comparison between these devices

    I think either of these options would be good for your system. But please let me know what you think!

    Regards,

    Kameron