If you only need to switch 5V, then the SN74CB3T16211, which has an on-resistance of <10Ω should work fine.

I don't believe you ever stated what maximum voltage you need to switch(?).

I apologize, i was not aware that voltage had a strong influence in switches. The maximum voltage would be about 2.5V since the circuit is part of a wheatstone bridge where the bridge voltage is 2.5V

 

Here is an approach using PSOC. I was able to route 48 channels onto one chip.
Resources left (right window) looks like I could squeeze another 16. Would have to
try it to see if it routes.

Plenty of resources left, could add a debouncer and a button input to control the array.
Could make it latching.....push to go on, push to go off. Button could be a cap sense
button to eliminate mechanical button.

Only code that has to be written is one line of code for each 8 inputs to turn them on/off
so 6 lines of code for the 48 outputs shown. So there would be a small latency between
turn on of the first 8 channels and the last 8 channels, I am guessing << 50 uS.

So everything is on 1 chip as shown. So top component (a component is an onchip
resource inside PSOC) is actual analog switch array, next is pins array for connecting
mux to external world, and below control registers to write to in code to turn on/off
analog switches channels.

View attachment 182774

So this is one analog signal in, distributed to 48 outputs. Could also add a OpAmp
buffer (also onchip) to the signal input. Or could use the onchip 4 opamps and buffer
the outputs in groups (for this exampe) of 12. Many possibilities. One chip.

Regards, Dana.

Thank you Dana. I have not heard of PSoC until you mentioned it. It looks quite interesting and by the looks. Its easy to progra as well. I will need to learn more on this. I was planning to do this directly with an external switch(the bus switch) but the microcontroller with 48 channels seems to be an interesting idea. I want to learn and explore more on this subject

 

Some short videos here -

https://www.cypress.com/video-library/PSoC-Software/psoc-creator-101-lesson-1-introduction-0/108116

Low end parts, some overlap with above -

https://www.cypress.com/training/psoc-101-video-tutorial-series-how-use-arm-cortex-m0-based-psoc-4

Bluetooth videos -

On programming, it programs like a "normal" processor, using C. But a great
deal can be done with little of no programming, like your application. Think
a breadboard full of logic, do it in PSOC, no programming like your breadboard.
But if you want to use all other sophisticated onchip resources, like DSP, PWM,
Quaddec, LCD, 20 bit DelSig, 12 bit SAR, OpAmps, COM.....you will need to do
the coding. Note all resources have a lot of prewritten APIs you use in your code,
you do simple calls and pass variables to these API functions, makes coding
very productive.

IDE is free, low costs board ~ $10 - 25 like -

https://www.cypress.com/documentati...oc-5lp-prototyping-kit-onboard-programmer-and




Regards, Dana.

 

Thank you. I am going to pursue more on this option as well. The board is pretty cheap as well. Ill give it a shot

 

That board, it has the high end processor on it, but has one limitation, the
number of gpio brought out. Note there are actually two 5LP parts on it, one
used for target, the other to debug/program it. Normally when a project is
finished you snap off the programmer side. But you can alter its firmware
and use it, you just cannot debug (it can't debug itself). And thje snap off
has almost no I/O brought out to board edge.

A third party board has more I/O, but less costly than high end Cypress
board with full I/O.

https://www.sparkfun.com/products/13714

Or you could use two of the $ 10 boards and a little programming with them talking to each
other. Or do your own layout, eg. just use chip on your own board.

Note, in the low end there are $ 4 board, PSOC 4, but w/o debug, so I only would consider
them for a project where you dev on the $ 10 boards, then program up project into $ 4 boards. There is a debuggable PSOC 4M board, FYI.


Regards, Dana.