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TMUX1208: Issues with possible interference or powering off?

Part Number: TMUX1208
Other Parts Discussed in Thread: TMUX1574, TPS2116, TMUX1108, TMUX1308

I'm using a TMUX1208 powered by 5v to multiplex a 3.3v VCC wire from my modem to the source but it’s possible that voltage/current becomes unstable after 3 hours.

The modem I’m using will shut off if it detects the 3.3v connection is unstable. I was using the TMUX1574 just fine, no disconnects or interference. I've been able to pin point that it's the TMUX1208 by hardwiring the VCC wire to the source (bypassing the TMUX1208) with no issues.

So basically if the tmux1208 fails to supply enough 3.3v power to the source then the modem will shut off and require a reboot.

  • The TMUX1208 has a higher on-resistance than the TMUX1574. These devices are designed for signals, not for large currents. What is the peak power consumption of the modem? A power mux like the TPS2116 might be more appropriate.

  • Thank you Clemens. Do you have anything that I can use for 1:8?

  • The 8:1 switch with the lowest on-resistance is the TMUX1108.

    (This is a very unusual requirement. Why are there eight power sources?)

  • I multiplex the VCC (supplied by another component) to power the 8 cards on/off. I also have a multiplexer on the IO and CLK lines but with a TMUX1308. I successfully used a series of TMUX1574 together but the footprint/pricing got too large.

    I can try to just run a VCC directly to all cards and don’t ground it but I would need to put pull down resistors which I'll test out on a breakout board tonight.

  • Hi Cho,

    Thanks for the feedback here. Clemens makes a good point here that the devices are largely intended for signal switches which is the root cause of the issue here.

    If you're able to order some samples of the TMUX1108, I'd be curious if it works similarly to the TMUX174 in operation since it's Ron is closer to that device. Otherwise, a power switch will likely end up being what you need. 

    Let us know how the breakout board experiment works out for you as well!