XTR111: XTR111 Initial Accuracy

Lei wang

Part Number: XTR111

Hi SIR:

I use the XTR111 input 0.8Vto 4V to be 4mA-20mA. i find when I want ouput the 20mA it only 19.985. the error (20-19.985)/20 =0.075% but if the output Current under the 20Ma example 19.6ma the Error (19.6-19.589) /19.6=0.056%. why the 20ma Error is bigger than under 20mA.it will effect my product Accuracy

over 7 years ago

0 Tamara M Alani over 7 years ago

TI__Genius 10850 points

Hi Lei,

Thank you for your post. The nonlinearity depends and changes with IOUT. As IOUT is increased, so does nonlinearity. This is shown in the "ELECTRICAL CHARACTERISTICS" table on page 3 of the datasheet: http://www.ti.com/lit/ds/symlink/xtr111.pdf

-Tamara

0 Lei wang over 6 years ago in reply to Tamara M Alani

Expert 1620 points

However, the data sheet value has been exceeded

0 Yangbo over 6 years ago in reply to Tamara M Alani

TI__Intellectual 1690 points

Hi Tamara,

What is the best accuracy with XTR111? In the datasheet, the maximum nonlinearity is 0.02%. Does it mean the best accuracy is 0.02%. If not, please let us know how to calculate the accuracy we can get. we want to achieve 0.05% accuracy.

Regards,

Yangbo

0 Tamara M Alani over 6 years ago in reply to Yangbo

TI__Genius 10850 points

Hello Yangbo,

The XTR111 is optimized and designed for 0-20mA applications; and its errors are only specified for the 0-25mA range in the datasheet. An estimate of the total accuracy can be calculated as follows for the 0-25mA full-scale range. Using the square root of the sum of squares:

The total error (estimate) = sqrt((offset_error)^2 + (gain_error)^2 + (linearity_error)^2)

Parameter	Typical	Maximum
offset error (%)	0.002	0.020
gain error (%)	0.015	0.100
linearity error (%)	0.002	0.020
	Typical	Maximum
Total estimated error	0.015	0.104

	Current error (µA typical)	Current error (µA maximum)
25mA range	3.82	25.98

So a rough or approximate total accuracy error is approximately ±3.82uA accuracy typical, about ±26uA maximum for the standard 0-25mA range.

-Tamara Alani

0 Tamara M Alani over 6 years ago in reply to Yangbo

TI__Genius 10850 points

Hello Yangbo,

In addition to the error I explained above, you also need to include the external transistor error. The datasheet specifies parameters for the XTR111 alone, so anything added around it would also contribute to your error.

-Tamara

0 Tamara M Alani over 6 years ago in reply to Tamara M Alani

TI__Genius 10850 points

Hello Yangbo,

We hope your issue was resolved. I am going to close this thread now.

-Tamara

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XTR111: XTR111 Initial Accuracy