TMUX136: Application and Cascade capability

Hi Wes,

The key careabout when deciding if a device can support a given protocol is supply voltage and bandwidth. That being said, it appears the TMUX136 can support al of these given the 6GHz bandwidth of the device. 

You can indeed cascade these devices as well! Fortunately, the team has recently released an app note on this exact topic. This app note covers the impact of cascading on insertion loss as well! You can expect your insertion loss to roughly double when cascading 2 muxes and an increase in loss from there - although not linear. 

 Unfortunately, we do not spec insertion loss directly in our datasheet. At lower frequencies, the insertion loss will almost be directly related to the on-resistance of the switch. While as you go up in frequency, any parasitic capacitances can be more influential as well.

Below is the frequency performance curve of the TMUX136. As you can see, the insertion loss will typically be around 1dB at 3GHz and 3dB at 6Ghz (nominally).

For ac coupling caps, this device is a passive FET switch and may be properly operated with or without external components as long as the datasheet specifications are satisfied.  You may put a AC coupling capacitor on the signal path without issue as long as there is a DC bias somewhere on the other side of the switch keeping the signal above 0V.

I hope this helps!

Let me know if anything else is needed here. 

Regards,

Alex

Hi Alex,

First of all thank you so much for this detailed answer and the application notes, this has helped greatly and also confirmed some of my simulation practices :). 

The only, other question I have regarding this device is (please forgive me if I have overlooked this in the data sheet) the maximum port A to COM1/PORT B to COM2 voltage, I think if I have read correctly, the TMUX136 can handle 5V signals?

Kind regards

Wes

Hi Wes,

Technically, yes, the TMUX136 can handle 5V I/O signals, but this falls under the absolute maximum ratings for the device. Exposure to absolute maximum rated conditions for extended periods may affect device reliability.

The recommended operating conditions state a max of 3.6V should be going through the switch.

Regarding DS280MB810ZBLR, this is an HSSC part so I'll move this thread to them in order to chime in on this inquiry. 

Regards,

Alex

Hi Wes,

While the DS280MB810 does not have a protocol dependency, it acts as a linear redriver. Depending on the signaling level, it may not be suitable as a general purpose MUX.

For example, I would expect the DS280MB810 to work for several different Ethernet applications, but I believe RS232 has a high signaling level that may not be suitable for DS280MB810.

Thanks,

Drew

Hi Wes,

The 2 Ohms indicated in the app note appears to be a typo. We'll get that fixed! For clarification, the typical Ron is as indicated in the device datasheet - 5.7 Ohms. Sorry for any confusion here!

Regards,

Alex

Hi Wes,

I discussed the compatibility of DS280MB810 across various protocols with a teammate, and they highlighted that they had discussed a similar topic with you.

In general, I think the challenge is that different protocols have different physical level requirements, such as different AC/DC coupling requirements, or half duplex vs simplex communication. Additionally, Base-T ethernet has different electrical signaling than 10G/25G ethernet.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1324357/tusb501-general-enquiries

To specifically address your question, the DS280MB810 would be a good fit for 10G/25G ethernet, but I would not recommend it for USB/HDMI applications.

Thanks,

Drew