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ADS7142: ADS7142 datasheet error

Sunny Qin
Expert 4890 points

Part Number: ADS7142

Hi team,

our customer found an error in ADS7142 datasheet figure 50：

could you help to confirm it?

Thanks.

Regards, Sunny

  • 0
    TI__Guru** 100095 points

    Sunny,

    Our ADS7142 expert is out of the office right now, so I'll go ahead and send a response.

    In the mean time, the diagram looks correct to me. Is there a reason the customer thinks this is incorrect? Normally, after a read from the device, you would get an ACK from the master. This would indicate that the master has received the data. I would note that this is a master response, and the ADS7142 doesn't have control over the master response.

    I've seen some cases where the master does not send the ACK. In the end, this last ACK is not really necessary. The master has received the data and the sends the STOP condition, ending the I2C transaction.

    Joseph Wu

  • 0 in reply to Joseph Wu
    TI__Expert 4890 points

    Hi Josehp,

    this is confired by customer, this is not A signal indeep, and other customer in Chinese version E2E also show this issue:

     

    could you help to double confirm with team?

    Thanks.

    Regards, Sunny

  • 0 in reply to Sunny Qin
    TI__Guru** 100095 points

    Sunny,

    I've forwarded this post to the design group that developed this device, and I am waiting to see how they respond to this question.

    However, I am still unsure how the datasheet is wrong. I've read through the post you referenced. And while there may be a problem with the customer read, it is the host that responds with the NACK, not the device. If the host ACKs or NACKs, it shouldn't matter to the slave device.

    If the device is expecting the NACK, how does this change the response? The device received the I2C STOP, and the transaction is over.

    I would note that there is a figure for Reading Data from the Data Buffer, which does have a NACK at the end of the transaction.

    However, the result should be same. The master reads the data from the slave. When the read completes, the ACK or NACK is followed by a STOP, and the I2C communication completes.

    Regardless, the product development group may have additional comments.

    Joseph Wu

  • 0 in reply to Joseph Wu
    TI__Expert 4890 points

    HI Joseph,

    Many thanks for your comments, i will ask customer to double check it, if you have some feedback from design team, please also let me know.

    Regards, Sunny