Question
I am using the AD5791 in an application which incidentally also requires a
precise reference voltage that is exactly half of the positive reference
voltage of the AD5791.
Is there any reason why the 6.8 kOhm -6.8 kOhm resistor divider connected to
the RFB and INV pins could not be used for this purpose?
If I connect the RFB pin to ground and buffer the voltage present on the INV
pin with an external op-amp, I should have a precision voltage that is exactly
half the positive reference voltage of the AD5791, shouldn't I?
If I could use these pins like this, it would save me an external resistor
divider and presumably the two 6.8K resistors track very accurately.
Answer
Is there any reason why the 6.8 kOhm -6.8 kOhm resistor divider connected to
the RFB and INV pins could not be used for this purpose?
We had some internal discussions about your application. We came to the
conclusion that it should work out well. The R1 and RFB resistors are well
matched and the temperature stability is way better than from two discrete
resistors.
Yes with
I have to say that this configuration was never characterized, because we did
not see a particular for Vrefp/2.
If I connect the RFB pin to ground and buffer the voltage present on the INV
pin with an external op-amp, I should have a precision voltage that is exactly
half the positive reference voltage of the AD5791, shouldn't I?
Yes you are right, this should be exactly half the positive reference voltage.