Other Parts Discussed in Thread: INA350, INA849
Hi team
We are designing a new data acquisition circuit for which we are thinking on the INA851 instrumentation amplifier.
The reason for using the INA851 is that we want to measure the sensor output and to eliminate the possible common mode ate the input. In addition, the INA851 has a differential output that can drive the following ADC (with differential inputs).
Even if the differential outputs of the INA851 can drive the differential inputs of the ADC, we think that probably we will need to add a common mode at the output of the INA851.
For doing this, in normal instrumentation amplifiers it is suggested to use an OPAMP which introduces an offset at the REF pin. This is a very common recommendation in the literature.
However it is also said that “Voltage reference devices are an excellent option for providing a low impedance voltage source for the reference pin” (INA350 Datasheet on page 25, INA849 on page 20).
Can you propose us the configuration for this offset with a Voltage reference? In terms of precision, which is the better solution? the one based in OPAMP or that based in a reference?
In the case of INA851, the offset has to be applied at the VOCM pin. According to page 22 of the datasheet it seems that the OPAMP for applying the offset is already integrated. So can we be confident if we apply the offset with an external resistor divider? Or shall we add another external OPAMP? The “reference” based solution should also be valid?
Thank you in advance for your answer
inigo
