Tool/software:
Hi,
I designed a RTD circuit with the help of INA333, Issuse is the output not varying linearly w.r.t Vdiff. please find the below images.
Additionally, when the RTD is disconnected, the difference between IN+ - IN- is approximately 9.5V, it cause to damage IA's, Could you explain the cause of this and suggest how to protect the circuit under these conditions?
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Hello Manohar,
Check what your input common-mode and differential values are when the input begins to respond non-linearly. Then, once that is determined, check that in reference to the VCM vs Vout plot in the Analog Engineer's Calculator.
For the disconnect condition, there is no current return path for your IS1 and IS2 when the RTD is disconnected. Adding a resistor to GND will allow the 500uA to be dissipated and it will not charge the input nodes.
Best,
Gerasimos
Hi Gerasimos,
I would like to clarify some observations regarding the system behavior.
When the RTD is disconnected, there is a return path for IS2 via Rseries, R7, and R8. However, when we establish a return path for IS1, it influences the voltage drop across the RTD.
Additionally, I have noticed that even when increasing the gain beyond 3, the system does not produce a linear output as expected. I would appreciate a clear and detailed explanation to help me better understand the underlying causes of this nonlinearity.
Thank you for your support. I look forward to your insights.
Regards,
Mamohar.k
