Mitch <hunrudpop <at> gmail.com> writes:

>=20
> I am fairly new to multi-channel ADC sampling.
>=20
> I have a ADS7828 and trying to sample all 8 channels - just measure all o=
f
> them once a second.
>=20
> I found that if I sample only one channel, I get very little noise and th=
e
> values look reasonable.
>=20
> But if I sample more than just 1 channel, it seems like the value of one
> sample has some kind of "leakage" to the value of the next. By increasing
> the voltage on channel 1, I actually measure a voltage increase on channe=
l
> 2. The "leak" occurs all the way down the chain.

Mitch,=20

This looks like sampling problem.  It can happen when you start conversion
immediately after selecting new channel.  Introduce delay between channel
selection and start of data conversion.  Sine you are sampling at 1Hz, you
can easily afford 1 ms for delay. =20
Also, low impedance sources will help, the low impedance source will
recharge sample/hold capacitor faster. =20

Hope this helps,

Sergey


--=20
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