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ina203 linearity

Kamal Najmi
Expert 3425 points
Other Parts Discussed in Thread: INA203, INA205, INA282

hi,

my customer would like to use the INA203 and measure the current with a CMR from 0V to 60V.

Current variation between 40ma TO 1.1A

he choose 0.1R sense and figure out that the Figure 32 from the datasheet showed only the test with the INA205 with different common mode value>

is the part tested with Vsense = 4mv

what is the diff between all these VCM1....4

is it possible to get a linear output voltage showing the image of the currentvariing form 40mA to 1.1A?

If not do you have a better solution?

thank you kamal

i have the sch please let me know if you need it.

 

 

  • 0
    TI__Genius 14825 points
    Kamal,
    The INA203 will have very bad error with Vsense < 20mV. The specification table only guarantees performance above 20mV, and figure 6 of the data sheet shows how the error increases as Vsense goes below 20mV. The applications section, pages 11 to 13, describe how the output responds to inputs in all conditions of common mode and Vsense.

    It's not impossible but recommended to avoid using a 1-ohm resistor as the shunt; resistors above 50mOhms start to have increased errors as well as the input bias current imbalances generate errors and the current drawn off the common mode to power the front end of the device becomes more noticeable with the small sense current. If the precision needed by the application isn't very high, this can be an option.

    For a better solution, I would recommend looking into the INA282 as it accepts Vsense down to 0mV, a gain of 50, and accepts common modes from -14V to 80V.

    Best regards,
    Jason Bridgmon