ADCs .. noise is it normal ?

[[email protected]]

Hi all!

I`ve choosed TLC4541 16-bit ADC for my design.
One thing is driving me crazy ..when I connect Vin to Vref (+5V) and do
few measurements one by one i do get quite big noise(error)
here are some samples :

FE4E
FE7E
FE84
FE55
FEC9
FEC9
FE96
FE68
FE56
FE73
FE86

to get acceptable error(nose) [+/-4] i need to do averaging of 1000
samples
again some samples...:

FE85
FE83
FE84
FE85
FE83
FE84
FE84
FE84
FE83
FE85
FE85
FE84
FE85
FE84
FE84
FE84
FE84
FE85
FE85
FE84

my question is:
is it normal for ADCs, or I choosed a bad one?

best regards
DM

 

[[email protected]]

i did following
i used tl431 to get 3V and connected it to Vref and Vin.. what i get is
... noise..
FF80
FFB8
FFB8
FFB8
FF8A
FFBE
FFA6
FF80
FFB8

any idea ?
u think it is normal for ADCs ?

best regards
david

 

[CWatters]

i did following
i used tl431 to get 3V and connected it to Vref and Vin.. what i get is
.. noise..
FF80
FFB8
FFB8
FFB8
FF8A
FFBE
FFA6
FF80
FFB8

any idea ?
u think it is normal for ADCs ?

best regards
david

The inputs Vin and Vref aren't the only way noise can get in.