[ts-7000] Re: ts-7250 settle time (MAX197)

["charliem_1216" <>]

--- In  "tseredynski" <> wrote:
>
> Hello,
> 
> I've tried looking at the ts-7250 datasheet and manual, as well as the MAX197 
> datasheet, but I am still unsure of the settling time when switching channels 
> on a ts-7250 with MAX197 ADC (optional component for the ts-7250).  Would 
> anyone happen to know how much time it takes for the signal to stabilize when 
> switching channels, before I can take a new reading?
> 
> The closest I got to finding out was in the datasheet of the MAX197:
> 
> http://datasheets.maxim-ic.com/en/ds/MAX197.pdf
> 
> on page 8, at the end of the first paragraph it says
> 
> "A low impedance input source, which settles in less than 1.5&#956;s, is 
> required to maintain conversion accuracy at the maximum conversion rate."
> 
> Which I can't decide if that means that the settling time is then at most 
> 1.5us, or if that just means it will take the next reading in 1.5us and I 
> need to make sure that my signal is stable before then...
> 

Well, closest to the latter.  It is describing the output impedance you need to 
have in your source conditioning circuit, so that the input is not still 
settling when the 197 T/H goes from Tracking to Holding.  The analog value at 
that time will be digitized, whether the signal is settled or not.  

Sounds like they are describing the settling time of the input MUX without 
really coming out and saying it.  Most chips can take consecutive samples on 
one channel faster than they can with a channel change, but I don't see that 
described here.

The timing diagrams explain in more detail.

regards, ........ Charlie

> Can anyone help me out?
> 
> Thanks,
> 
> Tyler
>




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