Confused about this datasheet. INA139

[fc3000]

Hi all.
I am using  a INA139 in my project.
As i was studying the datasheet, cannot understand the chart below.
The output error is both negative and positive value!!
Please could you explain how to read the chart.
Regards.



This is the full datasheet: https://www.ti.com/lit/ds/symlink/ina169.pdf

[Psi]

Not sure I understand your question.

Error can be positive or negative.  Above the correct value or below the correct value.

In this case, as Vin gets lower the error becomes more negative.

[fc3000]

Hi. Thank you for the reply.
So, are you saying that the error is a deviation from the perfect output?
Regards.

[DavidAlfa]

Exactly.
If nominal output is i.e. 1V, that's the deviation over it, based on input voltage and working temperature.

[fc3000]

OK got it now! 

Regards

[Terry Bites]

Vin=(Vin+ - Vin-) is the voltage across the shunt, Is*Rs. Vin is referenced to supply voltage and the voltage across the load.
All these factors and temperature will lead to error terms. Most sense amps are not all that precise because the market doesn't demand it it.
Battery charging, motor shunts etc...
There are exceptions of course.