Signal Aquisition/Signal monitoring

[geomit]

I am curious if anyone has any good ideas where I can get a "high voltage" input analog multiplexer/demultiplexer. Preferably the device would be 16:1 (I could live with 8:1). I am looking for a voltage input range of 0 to 100VDC. Thus far it has been a quest for the holy grail.
Any input would be most appreciated.
Thank you.

 

[melone]

What resolution do you need?

 

[geomit]

Hmm...
Resolution. I don't quite understand what you mean.
As far as the signal integrity through the MUX, it is not a big concern. The smallest voltage I will probably see is about 1-5VDC. It is the larger voltages I am concerned about.

 

[WarmElectTech]

scale it down and if needed scale it up again.

 

[IRstuff]

That high a voltage requires either:
> scaling, as mentioned above
> relays
> DIY mux using high voltage Mosfets

TTFN

 

[cbarn24050]

Hi, you can use opto isolators to do this.

 

[geomit]

Thank you all mindful engrs!!!!!

I have thought about all you have proposed.
Of course in the real world, we have to think about cost.
I should have mentioned earlier that my goal was to measure 128 channels. 16:1 or 8:1 MUX/DEMUX would work as cascading them together but I needed the advice on the "seed". Imagine scaling down the 128 lines before it got to the MUX/DEMUX. That is a lot of components if I were to multiply by 128. : )
Photo-MOSFET relays are a god send but they are expensive, not only in cost, but real estate on a PCB.

Thank you for all your thoughts.
If you think of anything more please contact ASAP!

 

[IRstuff]

Then, again, in the real world, you have to look at reality.

If this is something that's worth doing, then your customer will have to pay the price to get what he wants.

Your best choice will still probably be relays, something like what Keithley has:

http://www.keithley.com/storefront/...trol&clickPath=Products^Switching and Control

TTFN

 

[Chuckles159]

Like it or not, you're going to have to scale down each input. However, all this takes is a pair of resistors on each input. This will take up a lot less room than relays or high voltage mosfets. That's because, even if you multiplexed at the high voltage, you're going to have to scale down after the switch anyway as you will not be able to find a 100V input ADC anyway. The only real kicker here is the accuracy you need. If you need better than 1%, you're going to have to buy more expensive resistors, select them or add trim pots.

 

[OptoMark]

The relay solution is probably the easiest to implement. You can get Opto SSR's in SOP packages to minimize your board space. I would recommend looking at the 400V telecom relays, they are overkill voltage wise, but the high volumes keep the price of those relays low. NEC makes some good ones.