MAX3243E: Recommended DPST switches.

Kengo.Y

Part Number: MAX3243E
Other Parts Discussed in Thread: SN74LVC1G3157, MAX3232E, TMUX6119, , TMUX6234, TMUX6236, TMUX6219

Hi team,

My customer is looking for an RS232 SPDT switch.
Could you suggest a device in 2-input/1-output configuration?

Sincerely.
Kengo.

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 319830 points

Are you switching logic-level signals, or bus signals?

0 Kengo.Y over 3 years ago in reply to Clemens Ladisch

Guru 11335 points

We plan to input logic signals from the outside.

0 Clemens Ladisch over 3 years ago in reply to Kengo.Y

Guru 319830 points

You can use any switch that supports your logic voltage. Here is a search; you probably want the SN74LVC1G3157.

0 Kengo.Y over 3 years ago in reply to Clemens Ladisch

Guru 11335 points

Thank you for your comment, Clemens.

SN74LVC1G3157 is a single supply at 0 ~ 5V.
However, MAX3232E can provide positive and negative inputs and outputs.
I think SN74LVC1G157 would not be acceptable.
How about this?

Sincerely.
Kengo.

0 Clemens Ladisch over 3 years ago in reply to Kengo.Y

Guru 319830 points

So are you switching logic-level signals, or bus signals? To which pins of the transceivers will the switch be connected?

0 Kengo.Y over 3 years ago in reply to Clemens Ladisch

Guru 11335 points

Sorry, I was mistaken.
They want to switch all bus signals.

+1 Clemens Ladisch over 3 years ago in reply to Kengo.Y

Guru 319830 points

Valid RS-232 signal levels are up to ±15 V. Switches like the TMUX6119 can handle this, if you have appropriate supply rails.

The actual output voltage of many RS-232 transmitters is lower. What ICs are you using? How many channels do you need to switch? What power supply voltages do you have available?

+1 Parker Dodson over 3 years ago in reply to Kengo.Y

TI__Guru 53382 points

Hi Kengo,

If you are switching all the bus switches on the MAX3243E you need 8 channels for the multiplexer for the MAX3232E you need 4 channels. RS-232 can have up to +/-15V on a line which will require a mid-voltage multiplexer with +/-15V source - the TMUX6119 is a potential option but you'd require multiple IC's. The MAX3243E typically is only putting out +/-5.4V - but I think because of the range the TMUX6xxx or TMUX7xxx families are still the best bet in finding a switch that will work. However I am going to tag the Multiplexer team in the reply to see if they have another option that they may want to highlight. In general a lot of switches don't integrate too well with RS-xxx standards due to the large possible voltage ranges - there are work-arounds but they aren't always the most practical as they usually require voltage supplies beyond what is needed for the transceivers themselves.

Best,

Parker Dodson

+1 Bryan Marshall over 3 years ago in reply to Parker Dodson

TI__Genius 10974 points

Hi Kengo,

For a 2:1 switch with +/-15V capability, you can looking into our TMUX62XX family which support voltages up to +/-18V. Some suggestions would be the TMUX6219 (2:1x1 channel), TMUX6236 (2:1x2 channel), or the TMUX6234 (2:1x4 channel).

If you have other requirements, please let me know and I can help suggest other devices as well.

Thanks!

Bryan

0 Kengo.Y over 3 years ago in reply to Bryan Marshall

Guru 11335 points

Hi Bryan,Parker, Clemens

Thank you so much for your help !!
I understood.

I'll recommend TMUX62XX family to my customer.

Sincerely.
Kengo.

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MAX3243E: Recommended DPST switches.