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TMP112: About the power-up sequence

Kenji Ohno1
Genius 5095 points
Part Number: TMP112

Hi ,

Our customer have problem.

Data can not be read rarely when SCLK is set to High from before power-on.

If SCLK should not be set high when power is turned on, when should they turn SCLK high?

Best Regards,

Kenji/Japan Disty

  • 0
    TI__Expert 5695 points
    Hi Kenji,
    Will you please share your I2C bus waveforms with us for better evaluation?

    Thanks!
  • 0 in reply to Jose Arteaga4
    Genius 5095 points
    Hi Jose-san,

    Thanks for your response.
    Sorry,I don’t have a waveform.

    First of all I would like to check the effect of communication line condition.
    Case 1. When power is on, SCLK is High. ---> A problem that can not be read infrequently occurs.
    Case 2. When power is on, SCLK is Low. ---> No problem occurs.

    Best Regards,
    Kenji
  • 0 in reply to Kenji Ohno1
    TI__Mastermind 36940 points

    Hi Kenji-san,

    Thank you for reaching out to us. There is no issue when biasing the SCL and SDA pins before the device is turned ON. The communication can start immediately before the power supply pin reaches specified voltage. However, assuming the power supply ramp has met the specified voltage. During at power-up, the temperature result register will be zero until the first conversion completes once the power is valided. The conversion time takes about 35ms max.

    Hope this helps. Let me know if you have further question.

    Aaron

  • 0 in reply to Aaron Heng
    Genius 5095 points
    Hi Aaron-san,

    Thanks for your answer.
    I think that the initial setting will be done when the power supply starts up, but is there no problem in going to read the data at that time?

    Best Regards,
    Kenji
  • 0 in reply to Kenji Ohno1
    TI__Mastermind 36940 points
    Hi Kenji-san,

    Yes you can immediately read at start-up, but the device will not split any temperature result until a valid power supply and the first conversion is completed.

    Aaron