ADS131M08-Q1: ADS131M08-Q1

Dear Sangil,

welcome to our e2e forum and thanks a lot for your interest in our ADS131M08-Q1.
Let me remove your company name from your post because this is a public forum. I will get back to you tomorrow with answers to your questions.

Regards,
Joachim Wuerker

Dear Sangil,

please find following my feedback to your questions.

1-1. I would like to calculate the total error to determine the accuracy of the IC. Please check if they are any missing elements in calculating the total error.
Total error : Offset error + offset drift + gain error + gain drift + integral nonlinearity + noise.
(Precondition : Gain 1, FSR 1.2V, Global chop mode disable, 32kSPS, OSR 128)
Those are the correct error terms to consider for an error analysis. You will find that the INL error is most likely negligible.
The VREF error and drift needs to be included in the calculation as well. The VREF error and drift shows up as a gain error and gain drift in the end.
For that reason you will find gain drift specifications in the datasheet which already include the drift of the internal VREF. If you use an external VREF then please use the gain error and gain drift specifications without the internal VREF drift and add the error contributions of the external VREF.
Because the various error terms can usually be considered as being uncorrelated, we usually add the error terms in a “root sum square” (RSS) fashion.
I personally usually look at the noise contribution separately from the DC error specifications. Means I usually calculate all DC errors for my total error analysis and then check if my noise performance supports that as well.

1-2. Is it okay to remove the error and drift caused by offset and gain if we run calibration?
You can definitely remove the initial offset, gain and VREF error terms if you perform an offset and gain calibration at a single temperature.
If you calibrate your system at multiple points over temperature, then you may also be able to remove the drift components.

1-3. Is it correct that the accuracy of 1.2V ref voltage is not considered in the ADC performance?
The ADS131M08-Q1 specifies the gain drift with and without the internal VREF. As mentioned above, the VREF error and drift shows up as a gain error and gain drift in your system.

2-1. The product is marked as "FS capable" instead of "FS compliant". I am curious about the meaning of the "capable".
Please refer to this overview of TI’s functional safety categories: https://www.ti.com/technologies/functional-safety.html
In contrast to a “FS Compliant” product, a “FS Capable” product is not developed using TI’s specific process for the development of functional safety hardware. It is developed using TI’s standard quality managed hardware development process. However we provide documentation for “FS Capable” products that can aid in the development of a functional safe system. The documentation typically includes:
- FIT rate data according to SN 29500 and IEC TR 62380 / ISO 26262 part 11
- Failure modes analysis
- Pin FMA (failure mode analysis)
For ADS131M08-Q1 you can find the documentation here: ADS131M08-Q1 Functional Safety FIT Rate, FMD and Pin FMA

3-1. We have been using TI's BQ79735-Q1 product. Could you explain the main differences compared to this product?
I don’t have a specific comparison between those two devices available right now unfortunately.
If you could tell me a little bit more about how you intend to use the device or what signals in the BMS you want to measure with it, I could probably give some more guidance.

4-1. I am curious about the schedule for this product, such as SOP schedule and PPAP schedule, Engineering sample schedule, etc.
The ADS131M08-Q1 released to market in 2022 already. It is running in series production. You can request the PPAP for the ADS131M08-Q1 already.

4-2. I am interested in the reference unit price of this product. If you could provide the price based on a volume of 100k/year for 5 years, it would be great.
Please reach out to your local sales representative regarding volume pricing. We don’t share volume pricing in the e2e forum.

Regards,
Joachim Wuerker