--- In "j.chitte" <> wrote:
>
> --- In "charliem_1216" <charliem_1216@>
> wrote:
> >
> > Hi --
> >
> > --- In "j.chitte" <j.chitte@> wrote:
> > >
> > > Hi,
> > >
> > > I am struggling a bit to get clean data off the ADC. Sometimes
> > > (rarely) it is just a couple of mV bipolar noise, ie 2 LSB on
> the 5V
> > > unipolar range I am using. This is fine and matches the spec
of
> the
> > > MAX197
> >
> > It's been a while since I used the MAX197 (project was shelved
> ...).
>
>
> Hi, thanks for posting back, I'd given up hope of a reply on this
one.
>
> I found mostly the problem was a lose connection on one of my
> regulators on the external board. I'm now down to 4mV which is
much
> more reasonable but probably should be better.
>
> >
> > > However, most of the time its 10 or 20 mV which makes a bit of
a
> joke
> > > of the 12bit ADC precision.
> > >
> > > I was wondering if there is enough external capacitance on the
> 197
> > > Vref.
> >
> > Looking at the TS-7250 schematic, it seems there isn't any
external
> > capacitance. The datasheet (as I'm sure you've seen) suggests
> 4.7uF
> > at REF (pin26) and .01uF at REFADJ. Schematic shows .1 and
4.7uF
> on
> > REFADJ.
>
>
> Yes , I'd looked into that. I actually think this is a TS
> documentation error since there is a capacitor on pin 26 , but
since
> it is a microscopic smc device I can't tell its value. It seems
too
> small to be a 4.7uF though!
>
> Since the TS schematic shows it connected to another pin I was not
> sure whether I could trust the value shown either.
>
> Their engineering team seem very competant so I think the residual
> noise may be from elsewhere but I'm checking everything at this
> stage. I'd have been happier if the documentation was accurate.
>
>
> >
> > >
> > > Anyone routinely getting better than this?
> >
> > What test setup are you using? I might be able to dust off my
TS-
> 7250.
> >
> > Regards, ...... Charlie
> >
> > >
> > > Thanks.
> > >
> >
>
> I have some op amps buffering my inputs on an external board. They
> feed into the 7250 via a ribbon cable.
>
> I was interested to know if I could expect to acheive full 12 bit
> accuracy with a bit of care.
>
> Thx
>
Not getting anyway fast with this.
I see continuous +/- 2mV which is expected 2LSB variations however
frequent +/- 6mV spikes are spoiling my day.
Nobody here tried to get accurate ADC on the 7250?
Thx.
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