SBOS437K May 2008 – November 2023 INA210 , INA211 , INA212 , INA213 , INA214 , INA215
PRODUCTION DATA
As with any difference amplifier, the INA21x series common-mode rejection ratio is affected by any impedance present at the REF input. This concern is not a problem when the REF pin is connected directly to most references or power supplies. When using resistive dividers from the power supply or a reference voltage, the REF pin must be buffered by an op amp.
In systems where the INA21x output can be sensed differentially, such as by a differential input analog-to-digital converter (ADC) or by using two separate ADC inputs, the effects of external impedance on the REF input can be cancelled. Figure 6-4 depicts a method of taking the output from the INA21x by using the REF pin as a reference.