INA326: Can I use INA333 Instead of INA326

Hello Manohar,

Yes, these are both low-voltage instrumentation amplifiers, however they have very different architectures. Be mindful of the differences when you are making the substitution.

Before using the INA333 in place of the INA326, know that while the pinout is the same, there are some implementation differences. You must connect a resistor to the "R2/Ref" pin for 326. Additionally the two devices will have different valid common-modes.

Check the valid common-mode range for your application using the analog engineers calculator. If you have ensured you are in an acceptable output range based on your input voltages, then you may use the INA333 instead of the INA326.

Best,
Gerasimos

Hello Manohar,

Please see the VCM vs VOUT plot for the INA333 with the configuration you have provided.

With a 5V, single supply, gain of 23, and a common-mode voltage of ~350mV to ~390mV, your valid output range will not exceed 600mV. Your max input voltage differential that can linearly be output is 25.3mV.

Generally the input common-mode range should be above the V- rail to avoid saturating the internal nodes of the instrumentation amplifier.

I'm not sure that the INA333 is a good fit for this application. You may want to look into a 2-amp INA with VCM near V-, like the INA122. Please note that the VCM vs VOUT plot in the analog engineer's calculator tool is incorrect for the INA122.

For additional resources to understand this behavior, please see the following TI Precision Labs Video: https://www.ti.com/video/6216438746001

Best,
Gerasimos