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ADS131E08S: ADC (24Bit) Recommendation Inquiry

Grady Lee
Genius 4555 points

Part Number: ADS131E08S
Other Parts Discussed in Thread: TMS320F28377S, , ADS131M08, ADS131M04, ADS131E08, ADS131E04, ADS131A04

Tool/software:

Hi, TI expert

There is an inquiry from a customer regarding ADC (24Bit) recommendation.

- Application : Fuel Cell, Battery Pack Charger/Discharger

The customer is applying TMS320F28377S and is planning to change the internal 16bit ADC to an external 24bit.

The first part I looked for was ADS131E08S_8CH_24BIT.

Can you recommend some suitable components for voltage/current control response?

(Preferably widely used and proven components.)

Please check. Thanks

  • 0
    TI__Mastermind 25035 points

    Hi Grady,

    thanks a lot for reaching out with your ADC inquiry.

    Do you have any more details as to what exactly the customer wants to measure in the application? E.g. battery pack voltage, battery pack current, individual cell voltages, etc.?

    And do you have any specific ADC requirements, such as:
    - Channel count?
    - Multiplexed or simultaneous-sampling ADC?
    - Data rate per channel?
    - Interface (SPI, I2C, parallel)?
    - Input voltage range that needs to be measured?
    - AEC-Q100 qualification required in case this is an automotive application?

    Regards,
    Joachim Wuerker

  • 0 in reply to Joachim Wuerker
    Genius 4555 points

    Hi, Joachim

    We will respond with the information confirmed by the customer.

    - Battery Pack voltage : ± 1000 V

    - Battery Pack Current : ± 1000 A

    - Cell Voltage : ± 5 V

    - Cell Current : ±300 A

    - Channel count : At least 4CH or more

    - Multiplexed or simultaneous-sampling ADC? : simultaneous-sampling

    - Data rate per channel? : The bigger the better.

    - Interface (SPI, I2C, parallel)? : It does not matter whether it is SPI or I2C. It is good if it is suitable for PID control.

    - Input voltage range that needs to be measured? : Vref around 5V

    - AEC-Q100 qualification required in case this is an automotive application? : Since it is a Battery Tester (charging/discharging), it does not have to be Auto (AEC-Q100).

    Please check. Thanks.

  • 0 in reply to Grady Lee
    TI__Mastermind 25035 points

    Thanks Grady for the additional information.

    Is this a battery "pack" tester then or a battery cell tester?
    For a battery pack tester I assume they only need to measure the charge/discharge current and the pack voltage?
    Why is the cell current smaller than the pack current? Are the cells not all in series?
    Any idea what signal chain is in front of the ADC to implement the current and voltage measurement?

    For >=4Ch simultaneous sampling 24-bit ADCs we can offer:
    - ADS131M04, ADS131M08 (only support 1.2V VREF)
    - ADS131E04, ADS131E08
    - ADS131A04

    (The last digit indicates the number of simultaneous-sampling ADCs within the device).

    They are all used in battery tester applications today already.

    Regards,
    Joachim Wuerker

  • 0 in reply to Joachim Wuerker
    Genius 4555 points

    Hi, Joachim

    Here is the answer to your question.

    Is this a battery "pack" tester then or a battery cell tester?

    For a battery pack tester I assume they only need to measure the charge/discharge current and the pack voltage?

    → Both a battery pack tester and a battery cell tester.

    Why is the cell current smaller than the pack current? Are the cells not all in series?

    → There are two product lines separately.

    Any idea what signal chain is in front of the ADC to implement the current and voltage measurement?

    → Shunt and if need sensors.

  • 0 in reply to Grady Lee
    TI__Mastermind 25035 points

    Hi Grady,

    thanks a lot for the additional information.
    In terms of signal chain they probably still have an INA between the shunt and the ADC inputs and for battery pack voltage measurement they will need some resistor divider. Not sure how they plan to measure the individual cell voltages.

    Once you have a schematic to share please let us know and we will be happy to review it.

    Regards,
    Joachim Wuerker

  • 0 in reply to Joachim Wuerker
    Genius 4555 points

    Hi, Joachim

    Thank you for your reply.
    I will request a review once TI_ADC is selected by the customer and the circuit diagram is shared.

    Thanks.

  • 0 in reply to Grady Lee
    Genius 4555 points

    Hi, Joachim

    I have an additional question from a customer.
    While checking the datasheet of ADS131E08, I would like to know what the purpose of the Calibration function listed in 9.3.2.2 Test Signals (TestP and TestN) is.
    Please refer to the related content below.
    Can you confirm it?

    Thank.

  • +1 in reply to Grady Lee
    TI__Mastermind 49475 points

    Hi Grady,

    The test signal is a square-wave internally generated at the frequency selected, you can actually see the signal in Section 4.4, Figure 16 of the ADS131E08EVM-PDK user guide. When the same test signal from one ADS131E08 ADC is used for multiple ADS131E08 devices, you could probably see a slight difference from the code of those devices, so you can calibrate them out with this test signal. However, please note that the test signal is intended as an example signal and it is not a very precise signal, so it really is not best used for calibration purposes. The primary purpose of this test signal is to verify the functionality of the front-end mux, the programmable gain amplifier (PGA), and the ADC as stated in the EVM user guide.

    BR,

    Dale