INA828： Which is the best Gain drift specification?

Kenji Ohno1

Genius 5095 points

Part Number: INA828
Other Parts Discussed in Thread: INA818, , INA821

Hi,

I can compare the gain drft with the Max rule, but I want to compare the actual ability value.

Even if you check the data, the unit is different.

I look best at INA818.

Which of INA818, INA828 and INA821 should be understood as the best Gain drift?

Best Regards,

Kenji

I can compare the gain drft with the Max rule, but I want to compare the actual ability value.

Even if you check the data, the unit is different.

I look best at INA818.

Which of INA818, INA828 and INA821 should be understood as the best Gain drift?

over 5 years ago

0 Tamara M Alani over 5 years ago

TI__Genius 10850 points

Hi Kenji,

Thank you for your post. I can help you.

You're right, the way the data is displayed for the INA828 and INA818 is different. The INA828 is referenced to +25°C. At +25°C, the Gain Error y-axis value is 0ppm. However, for the INA818, this is not referenced to +25°C. The Gain Error value seen at +25°C is approximately 47ppm. If you reference all values to this (add 47ppm to each data-point), you should receive a graph similar to that shown in INA828 datasheet.

We need to make note to make sure these graphs are consistently displayed. Thank you for bringing this up to our attention.

-Tamara

0 Kenji Ohno1 over 5 years ago in reply to Tamara M Alani

Genius 5095 points

Hi Tamara,

Thank you for your support.

I again compared Gain Error vs Temperature (G = 1).

Comparing the graphs of INA828, INA821 and INA818, INA828 has overwhelmingly better performance.

[INA828]

　ΔT = 125 ° C-(-40 ° C) = 165 ° C　　Gain drift = {0.7-(-1.7)} / 165 ℃ = 0.015ppm / ℃

[INA821]

　ΔT = 125 ° C-(-40 ° C) = 165 ° C　　Gain drift = {84-(-28)} / 165 ℃ = 0.68ppm / ℃

[INA818]

　ΔT = 125 ℃-(-40 ℃) = 165 ℃　　　Gain drift = {-40-(-67)} / 165 ℃ = 0.164ppm / ℃

My customer evaluated INA828 and found that it was 20ppm / ℃ at Ta = 50~80℃.

I think the results of the INA828 data sheet are too good. Can you provide some actual ability data?

Also, I think INA818 is a newer device than INA828. What are the features of INA818?

What should I use for the difference? I would like to know the effective difference.

Finally, INA821 is listed as "Average of 294 units".

Figure 30. Is Gain Error vs Temperature an average of 294 units?

Or is it just one average representative sample?

Best Regards,

Kenji

0 Tamara M Alani over 5 years ago in reply to Kenji Ohno1

TI__Genius 10850 points

Hi Kenji,

I will look into this with the product definer and get back to you ASAP.

-Tamara

0 Kenji Ohno1 over 5 years ago in reply to Tamara M Alani

Genius 5095 points

Hi Tamara,

I have been waiting for you for a long time.

Thanks for your special support.

Best Regards,

Kenji

0 Tamara M Alani over 5 years ago in reply to Kenji Ohno1

TI__Genius 10850 points

Hi Kenji,

I understand and I appreciate your patience.

How did the customer measure the INA828 gain error drift? Please share the schematic and test procedure. We especially need to know the following:
- What are the input sources? We recommend DP8200 DC power supplies.
- What kind of volt meter are you using? We recommend HP3458 DMM.
- How is the DMM connected? Output to ground? Output to input?
- What is the reference voltage?
- What is the common mode voltage?
- What voltage is seen at each input?
- What are the supply voltages?
- All schematic details and test procedure will help us determine whether or not the customer is correctly measuring this.
Figure 30 of the INA821 datasheet is an average of 294 units. It says it on the curve.
Here is a spec-spec comparison of the INA818 vs the INA828

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INA828： Which is the best Gain drift specification?