Re: 3.3v robustness

On Sun, 2 Nov 2008 03:56:19 -0800 (PST), Daveb <dave.bryan@xxxxxxxxx>
wrote:

On 2 Nov, 11:08, Leon <leon...@xxxxxxxxxxxxxx> wrote:
On 2 Nov, 09:00, Daveb <dave.br...@xxxxxxxxx> wrote:

Hi,

Does anyone have any experience/thoughts on the robustness of a 3.3v
CMOS Opamp configured as a differential amp with the inputs connected
via 10m cables to a strain gauge bridge in an electrically noisy
environment ? If I add clamp diodes from the opamp inputs to the rails
is there any difference between a 3.3v device and a 12v device in
terms of susceptability to damage from external transients, etc ?

Thanks
Dave

Why don't you put the op amp close to the strain gauge?

Leon

Leon,

The strain gauge is in a high temperature environment which is too hot
for signal conditioning electronics. Also, the mechanical part doesn't
allow easy location of a circuit board so we've elected to put the
conditioning remotely. The signal can be heavily filtered as the
sampling rate will be low. It seems there's a better choice of single
rail opamps with good DC performance with low voltage rails than with
higher voltage rails. Hence the question regarding the suitability of
the low voltage amps in such an amplication.

Regards
Dave

Call me weird, but there are fundamental reasons why a split supply
opamp will always work better at DC than a single rail opamp. If you
are willing to go to +/- 3.3 V or +/- 5 V for the first stage you can
easily get much better DC performance. Much of it is a result of
circuit topology. Just to push the point can you put the strain gauge
bridge in the same thermal environment? It will save you much trouble
if you can.

.

Relevant Pages

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  • Re: 3.3v robustness
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