Dear Guru's,

Need to know whether an analog mux/demux or switch of 16:1 (if this then better) or 8:1 Differential input/output is available in IC package. I am designing datalogger which has 16 differential analog inputs. I searched a lot on net by found only 74hc4052 like ics.
It would be of good help if you do so.

Thanks and regards.
p.r.b

 

hi pratik,
Welcome to AAC.
Is this type suitable.?
E

 

Thanks for fast reply sir.

yes this is it what i was looking for. Also dont they produce 16 channel differential mux. 16 dual : 1 dual.


Also can this Dg407be used for detecting thermocouple and rtd output voltages.

 

hi,
There is this Intersil series of mux IC's.
I would say the internal resistance of the analog gate could be a problem for mV signals.
E

 

What is the maximum plus and/or minus signal voltage, and what is the maximum multiplexer speed?

 

I would say the internal resistance of the analog gate could be a problem for mV signals.

I don't see that the internal (series) resistance will have any more relative effect on mV signals as larger signals.
In either case it's a percentage error of the signal voltage as determined by the load resistance relative to the mux resistance.

 

As we both do not know what the TS's project is, I don't see how you can make that assumption.
You may have noted he is also considering RTD's , so lets wait see what he is trying to do.

 

PSOC can easily handle this. You could ignore all the other onchip
resources and just use the HW with no coding to do the mux or do
the whole datalogger design in one chip.

Attached a list of components for PSOC 5LP family parts. A component
is an onchip resource.

This example shows 12 bit sequencing SAR, if you use DelSig that maxes
out at 20 bits. I only show the first channel wired to pins, got lazy.

See attached.

If you just want mux, no coding, then the onchip HW mux can be brought out
to pins, analog path and control pins for mux.

Attached. Note I did not wire this at all, you would wire all connections out to
pins using the GUI tool.

Note tool, PSOC Creator, is free. http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide

Regards, Dana.

 

As we both do not know what the TS's project is, I don't see how you can make that assumption.

And I don't see how the mux series resistance can affect mV signals more than larger signals.

 

Dear all,

Thanks for your reply.
Replies to all Guru's.

It was my fault i gave little info . Actually i am willing to design a data-logger for my Master Engineering project which will connect and log various sensor outputs. I need to connect themrocouple k type, rtd pt100 , 4-20ma current sensor and a 1-10volt output sensor. All these sensors swapable on any channel. And my datalogger will have 12 channels.

I decided to go with psoc 5lp and i am working on it. Internal psoc 5Lp can read and is suffiecient for 4 channels. And my datalogger will have 12 channels. Also i want to log data in sd card and usb drive also a modbus RS232 slave / tcp ip slave connection is required. I have completed all the modules . But now i got stuck when it came to pin limitations of psoc5Lp. I already invested in this chip and other sensors. Also time has been invested.

So decided to finish the project by using one last component which will take care of the pin limitation. So i called a helping hand regarding the analog switch / mux which can be cost .

I am lot confused about the analog mux Rds at on and matching as i think it will be difficult if the mv drops due to rds.

This is the actually scenario. And I have 2 months left to complete this project.

 

PSOC can easily handle this. You could ignore all the other onchip
resources and just use the HW with no coding to do the mux or do
the whole datalogger design in one chip.

Attached a list of components for PSOC 5LP family parts. A component
is an onchip resource.

This example shows 12 bit sequencing SAR, if you use DelSig that maxes
out at 20 bits. I only show the first channel wired to pins, got lazy.

See attached.

If you just want mux, no coding, then the onchip HW mux can be brought out
to pins, analog path and control pins for mux.

Attached. Note I did not wire this at all, you would wire all connections out to
pins using the GUI tool.

Note tool, PSOC Creator, is free. http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide

Regards, Dana.

Dear maam,
I am already a memeber in psoc community. I have taken help from community gurus also. Thanks for reply

 

I decided to go with psoc 5lp and i am working on it. Internal psoc 5Lp can read and is suffiecient for 4 channels

Why do you think you are limited to 4 channels ?

I am lot confused about the analog mux Rds at on and matching as i think it will be difficult if the mv drops due to rds.

That would be true if you were drawing a lot of current thru the mux, into A/D,
which you are not. The SAR is ~ 74K input R (you could always consider using
non sequencing SAR and OpAmp buffer = 10M ohms and separate internal mux).
The DelSig using buffer is 10 Mohms, w/o buffer also ~ 74Kohms.

Regards, Dana.

 

Dear dana ,

I didnt understand i need to use differential inputs of thermocouple and rtd . Also 4-20ma and 0-10volt sensor ouput to be fed to psoc adc via mux. I need atmost 2 X 12 channels=24 pin of psco dedicately. Also need pins for sd card spi interface, then rs232 modbus aswell.

 

Why do you think you are limited to 4 channels ?



That would be true if you were drawing a lot of current thru the mux, into A/D,
which you are not. The SAR is ~ 74K input R (you could always consider using
non sequencing SAR and OpAmp buffer = 10M ohms and separate internal mux).
The DelSig using buffer is 10 Mohms, w/o buffer also ~ 74Kohms.

Regards, Dana.

also the inputs are interchangable

 

also the inputs are interchangable

The input is differential or single ended depending on how you
config it.

What do you mean "interchangeable" ?

Regards, Dana.

 

The input is differential or single ended depending on how you
config it.

What do you mean "interchangeable" ?

Regards, Dana.

Dear dana,
interchangeable means one can use any channel for any sensor

 

i shall start new thread for this project design