AD7606 FAQ - What is the variation in the 1Mohm input impedance?

Document created by NiallM Employee on Nov 23, 2017
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A common question on the AD7606 is what is the tolerance of the 1M ohm input impedance? This can become important when there is a high external resistance on the analog input, greater than 10k ohms for instance, or when a sensor with a high output impedance is used.


The 1M ohm input impedance of the AD7606 is a typical figure and can vary from part to part. For a typical production lot this can vary between 0.93M ohms and 1.02M ohms, at ambient temperature. A greater variation will be seen over the full temperature range from -40C to +85C.


It is also worth nothing that if an external resistor is needed it can introduce a gain error. It is recommended that a closely matched external resistor is applied on both Vx and VxGND to reduce any offset error. See the datasheet for more details.