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TMP75: TMP75 transaction question

Iris Ye
Prodigy 10 points
Part Number: TMP75

I'm writing to inquire about some tmp75 we've recently discovered that non-ack with data we write. The failure rate for this issue is very low (1/50000).

The following is the transaction I captured via I2C analyzer: (tmp75 is addres0x4E)

Do you have any idea how to root cause the issue ? In which scenario TMP75 will non-ack with data we write?

  • 0
    TI__Genius 9720 points

    Hello Iris,

    Thank you for bringing up this concern. TMP75 has an default address of 0x48h when pins A0-A2 are grounded. I have listed all address combinations of TMP75 below.

    The pointer address to access the registers within the TMP75 are listed below.

    If this is not this issue, can you send scope shot of the I2C communication? This will allow me to catch further communication issues.

    Best Regards,

    Meredith McKean

  • 0 in reply to Meredith McKean
    Prodigy 10 points

    Hi Meredith, 

    We found that the TMP75 does not acknowledge the register byte (0x00), but it does acknowledge the address.

    Thanks,

    --Iris

  • 0 in reply to Iris Ye
    TI__Genius 9720 points

    Hi Iris,

    The Temperature Register is read only. By default, the pointer register is set to 00. At power-on if you perform a read transaction without first using a write transaction to set the pointer you will receive the contents of register 00. 

    Best Regards,

    Meredith McKean