EEVblog Electronics Community Forum

Electronics => Projects, Designs, and Technical Stuff => Topic started by: fc3000 on September 27, 2023, 10:55:28 am

Title: Confused about this datasheet. INA139
Post by: fc3000 on September 27, 2023, 10:55:28 am

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.

[attach=1]

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

Title: Re: Confused about this datasheet. INA139
Post by: Psi on September 27, 2023, 11:13:01 am

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.

Title: Re: Confused about this datasheet. INA139
Post by: fc3000 on September 27, 2023, 12:34:37 pm

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

Title: Re: Confused about this datasheet. INA139
Post by: DavidAlfa on September 27, 2023, 01:37:41 pm

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

Title: Re: Confused about this datasheet. INA139
Post by: fc3000 on September 27, 2023, 02:22:51 pm

OK got it now!  :)

Regards

Title: Re: Confused about this datasheet. INA139
Post by: Terry Bites on September 27, 2023, 05:59:31 pm

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.