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INA193 - Common mode issues

osmont jean-baptiste
Prodigy 70 points
Other Parts Discussed in Thread: INA193, INA168, INA271, INA282

Hi ,


I plan to measure a current through a sensor  resistor.

Specs are following :
•    Common mode : 0 to 51V
•    Current : 0 to 5A
•    Max drop voltage : 100mV
•    Settling time : 5µs

According to specifications, it seems that the INA193 suits well to this application

The simulation given by INA193 TI PSpice project available on TI website gives weird results :

Schematic:
 

Results:
 

So it appears that for a 50mV voltage drop on RSENSE, INA193 output is about 5mV instead of 1V.
This result doesn’t match with theory.

Moreover, results go back to normal if common mode voltage is decreased from 51V to 30V.

Have you any feedback of  relative to the INA193 PSpice Model, or rather have I done something wrong?

Thank you for your answer or insight to this problem.

Regards,
Jean-Baptiste OSMONT

  • 0
    TI__Mastermind 25865 points

    Hello Jean-Baptiste,

    We have verified that there is an issue with the INA193 model and apologize for the inconvenience.  Unfortunately we were not able to find a straightforward fix.  Therefore a correction will most likely take a considerable amount of time.

    Have you considered the INA168/9?  I have attached a TINA simulation that may be of use.

    jeanbaptiste.TSC
  • 0 in reply to Pete%20Semig
    Prodigy 70 points

    Hello Pete,

    First of all, thank you for your answer. Unfortunately I have also an current measurement stage with a negative common mode. It'd be better for us to use the same part for all current measurement stages.

    So I might have to trust INA193 specs and validate the current measurement solution with a lower common mode.

    However, INA193 and INA168 have the same pinout. So It would be a good insurance if anything goes wrong (but why would it ?).

    Have we any chance of having an INA193 PSpice model fix for the end of the month ? How long would it take ?

    Best regards,

    Jean-Baptiste Osmont

  • 0 in reply to osmont jean-baptiste
    TI__Mastermind 25865 points

    Hello Jean-Baptiste,

    I doubt that the INA193 model will be fixed within the next two weeks.  But, we have recently released the model for the INA271.  It has the same core as the INA193.  I have attached a TINA schematic that can get you started.  They are not exactly the same for the INA271 has provisions for filtering the output and some specifications are affected.

    Please be aware that for the INA193 and INA271 that for accurate measurements the shunt voltage should be greater than 20mV.  That is why I swept the load current from 1A to 5A in the simulation.

    I had also considered the INA282 for you, but it would not meet your settling requirement.

    Please let me know if you have any additional questions.

    jeanbaptiste01.TSC