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ADC references for ratiometric conversion of bridge with 10V excitation

Question asked by GSKelly on Feb 20, 2012
Latest reply on Feb 21, 2012 by MaryMc



Our lab has a large quantity of pressure transducers that are specified for 10 Vdc excitation. They have a nominal sensitivity of 3 mV/psi, which I assume is evaluated at the 10 V excitation level. As they are rated for 0-5 psi, if I'm not mistaken this gives them a mV/V sensitivity of 1.5 mV/V -- [(3 mV/psi) * (5 psi)] / 10 V.

Because they have a relatively low sensitivity, and because I tend to be a stickler for manufacturer's specs, I want to run the transducers with the full 10 V excitation. However, to reduce noise I would also like, if at all possible, to run the A/D in a ratiometric configuration. As I understand it, few to no ADC chips allow greater than around 5 V as a reference. What is the typical way around this, if any? Will a simple voltage divider work? I would guess that this would introduce noise as well, but I'm not sure.

On that note, can anybody recommend any ADCs that would be ideal for this task? To save on board space, it would be nice to have a complete AFE like the AD7730, but separate signal conditioning stages prior to the ADC would be fine as long as they are single-supply.


Thanks for any help you can offer!