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TS3A24157: Am I destroying it? Basic functionality doesn't work

Daniel Schultz
Prodigy 40 points
Part Number: TS3A24157
Other Parts Discussed in Thread: TMUX131, TS5A3359

Tool/software:

Hello forum,

I am testing a prototype product where I use the TS3A24157 to multiplex two signals. 
Testing my device (that doesn't work), I narrowed the problem down to the TS3A24157DGSR.

I made a new board with the multiplexer IC being the only part on the board.
However, I can't get basic functionality to work. I wired it all up as follows:


Carefully checked that the footprint I'm using is correct. Also tried mirroring (just in case of).

On the test board, I wired "ctrl" directly to VCC. VCC goes to a lab supply at 3.3V. Then turning on the lab supply.
Resistance is measured from sig_a to sig1_a.
Here, I expect near a short-circuit (Ron). However, my multimeter jumps from >1Mohm to 30kOhm in a periodic manner as if "IN" is floating.

Also tried to apply VCC at sig_a and measure voltage from sig1_a to ground. This also is not consistent. Measuring 1.4V and down towards ~100's of mV.

Something I have misunderstood here? Am I frying the IC everytime I apply power?

I have gladly used TS5A3359 and TMUX131 in similar designs without any problems. However, the TS3A24157 perfectly fits for this application (if I could get it to work). 
Before compromising and using another part, I would like to know if anyhow my testing is wrong.


Best regards, Daniel

  • 0
    TI__Mastermind 35168 points

    Hi Daniel,

    Nothing stands out as an issue in the way you're testing. Have you tried multiple units? Could be some ESD damage from handling. 
    The only other thing would be to just verify that your sig_a and VCC are actually at 3.3V via multimeter at the actual pins just for sanity (although I suspect you've already measured these).

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    Prodigy 40 points

    I have checked with multiple units and am operating on an ESD-mat.

    I verified that sig_a and VCC pins are actually at 3.3V.

    Datasheet states it's fine to leave the NO and NC pins floating, so this is not  the issue either.

  • 0 in reply to Daniel Schultz
    TI__Mastermind 35168 points

    Hi Daniel,

    Can you try measuring the RON using the method from the datasheet? Sourcing 100mA and forcing a voltage on the other side..

    Another thing to test is the board itself. Have you removed the device and verified that the board doesn't have any issues with it? No weird behavior between traces. Just verifying that the traces are indeed all isolated.

    Thanks,
    Rami