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AD7195 Reference voltage generator

Question asked by Ahygoon on May 13, 2014
Latest reply on May 13, 2014 by ChrisD.Rama


I have designed a measure chain with an AD7195 for strain gauges. I work with ratiometric reference (Load cell supply = 8V) and with a gain 64.

The reference voltage I want to produce is ~3.75V: limitation of PGA that  limit the range.


To generate my reference voltage, I first want to use 2 resistors (simple voltage divider) to splite the 8V. But as the reference input is not High impedance, I shall use low values of resistance (~100 Ohm) to make the divider. That lead to a "high" current and so high power in the voltage divider.


Because the reference is very important in the precision of the measure, I want to be sure to make it well.

With my design I'm affraid that because of the high power in the resistor, the value of the resistances will change during time because of wearing.


For another side, I prefere avoid using a follower ( Divider with High resistors (> 1k) + APO) that will increase the cost and change the circuit routing.


Do you have other solutions?


Is the consumption of the reference input constant? (so I can adapt the resistor and consider the reference input as a constant load)