channel-channel isoalation

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

sanjay_td@rediffmail.com - 30 Dec 2004 18:13 GMT

I give analog signals to 8 input channels then i convert it to digital
form using ADC then i give this count to microcontroller.

i.e....|iso amp|--->||-->|ADC|-->|opto isolation|-->|uController|

can i get good accuracy?
If i want channel to channel isolation then... upto what extent should
i give isolation?
What should i use for my scheme
a)mux & 1 ADC or
b)8 seperate ADC's to achieve channel-channel isolation???

if i use a)mux & 1 ADC then... can i call it as channel channel
isolation??
if I use b)8 ADC (12/16 bit) then...which is cheap & good accuracy ADC

how to get isolated power supply for each channel from single source(of
5V)

Reply to this Message

Mac - 30 Dec 2004 22:04 GMT

On Thu, 30 Dec 2004 10:13:09 -0800, sanjay_td wrote:

> I give analog signals to 8 input channels then i convert it to digital
> form using ADC then i give this count to microcontroller.
>
> i.e....|iso amp|--->||-->|ADC|-->|opto isolation|-->|uController|
>
> can i get good accuracy?

What is the frequency range of your signal? What sample rate are you
going to use?

I'm not sure I understand what kind of signal you are feeding to the
uController. Is it just the samples, in digital form?

> If i want channel to channel isolation then... upto what extent should
> i give isolation?
[quoted text clipped - 8 lines]
> how to get isolated power supply for each channel from single source(of
> 5V)

I doubt that you will need to use isolated power supplies. If your signal
includes low frequencies, isolating the power supplies might prove to be
problematic, anyway. In any event, we need a signal frequency range before
we can tell you how to isolate your power supplies.

It would be nice if you could start with an idea of how much
cnannel-channel isolation you need. From there, you could answer
the question of whether a mux would work. Personally, I think it
would be more reasonable to mux the analog signal. If you need
really good channel-to-channel isolation, you can use some tricks
such as putting two muxes in series. Other people will probably have
better advice about this.

Anyway, you should first,decide how much channel-to-channel isolation you
actually need.

--Mac

Reply to this Message

Electronics Forum / CAD / December 2004

channel-channel isoalation