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TS3A27518E: Issues attempting to program a WMX-L76C-N via SD card while using IC TS3A27518EPWR to MUX between 2 SD Cards

Chris Bayerlein
Prodigy 10 points
Part Number: TS3A27518E
Other Parts Discussed in Thread: TMUX1574,

Tool/software:

Hello,

I am attempting update a existing test system to be able to run 2 variants of boards. Each variant has its own firmware that needs to be applied via a SD card. Currently the SD card is inside of the fixture, attached via POGO pins to the PCBA and programs with no issues. I created a MUX to allow the system to select what SD card should be used based on the variant. I attached the PCBA via the same POGO pins  I am unable to program while using the MUX board inside the fixture.

I fully tested the MUX PCBA at my desk with no issues and I am able to program the board on both sides of the MUX. When installed into the fixture, programming fails, I have removed all other POGO pins expect what is needed to program at my desk to reduce any chance of noise. The failure during programing states it can not access a file. If I take the same board and SD card, I am able to program them by place the SD card directly into the PCBA. I also added the filtering cap between power and ground that the schematic does not show. 

Any ideas of what could be causing this, or any additional steps I should take to debug this?

  • 0
    TI__Genius 17600 points

    Hello Chris,

    Looking at the schematic everything looks fine with the actual mux.

    Fortunately I did find a older e2e where someone had a similar question to yours.

    Essentially for you application  the TS3A27518E might be adding to much capacitance to your bus and you should try using two TMUX1574 devices instead

    The post I sent has a lot more detail on how we can fix the problem you are seeing.

    Please let me know if this helps!

    regards,

    Kameron

  • 0 in reply to Kameron Hill
    Prodigy 10 points

    Hi Kameron,

    Thank you for the response and finding that older thread! After reading and discussing the proposed solution listed I am going to attempt to spin the board using the TMUX1574. 

    I will create a new thread if needed if this does not work!

    Thanks,
    Chris