I work with development and I have an instability problem in a project with INA332AIDGKR. We have 15 boards with the same hardware but each one with different behavior.
Our SCH is below:
Tks so much for helping.
Hi Gabriel,
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Best.
Raymond
Hi Raymond,
How u see, we are working with DC, G=191 and REF=1,22V.
Our question is, why the minimum value on out is under the 1,22V when your REF is 1,22V? Shouldn't the minimum value be 1.22V?
Best,
Gabriel
Hi Gabriel,
Thanks for the table reference. I think that I know the issue. The reference pin requires low impedance connection, such as 1.220V low impedance reference, 1.220Vref output from Op Amp buffer or 1.220V regulator (you can find 1.25V Vref regulator). Your zener reference does not meet low impedance requirements. Its zener output impedance is approx. 22kohm, see the capture image below.
If you feed the LM4041 into an op amp buffer and connect the output buffer to pin 5 and R44, then your issue will be solved.
/cfs-file/__key/communityserver-discussions-components-files/14/INA332-Vref-Issue-09252020.TSC
If your have additional questions, please let us know.
Best,
Raymond
Hi Gabriel,
One thing that you may be able to check out quickly is to change the resistor value from 22kOhm to 252Ohm, see the red square. This is a band-aid solution, and it should get close to your expected value. (5V-1.22V)/15mA = 252 Ohm. You can increase increase the reference voltage slightly and/or decrease +5V for the zener --> lower the Vref output impedance somewhat. Please let me know if you need further assistant.
Best,
Raymond
