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ADS7138-Q1: Inquiry Regarding "Data Setup Time" for I2C in Fast Mode

Jimmy Chen
Prodigy 60 points
Part Number: ADS7138-Q1

Tool/software:

Dear sirs,

I would like to confirm if the "Data setup time" in the table below refers to the time that the transmitter must satisfy when sending data. If so, does this mean I need to check the actual Data setup time in the datasheet of the transmitter IC when transmitting I2C data?

Could you please provide the actual Data setup time for the ADS7138QRTERQ1 IC when transmitting I2C data in Fast Mode?

Thank you for your assistance. I look forward to your reply.

Best regards,

  • 0
    TI__Genius 15700 points

    Hi Jimmy,

    Apologies for the delay, as I was investigating this same concern with my team.

    Your understanding is correct. In I2C terminology, the data that the controller send to the device must be stable at least 50ns before the rising edge of SCL in order for the device to correctly read that bit of data.

    Because of this device's specific digital design architecture, standard, fast, and fast mode plus share the same data in setup time (t_SU:DAT) and data in hold time (t_HD:DAT). It is only until the device is configured in high-speed mode (see datasheet section 8.3.13.4) that the data in setup time changes.

    Regards,
    Joel 

  • 0 in reply to Joel Meraz
    Prodigy 60 points

    Dear Joel,

    The datasheet specifies timing parameters such as Data Setup Time, but it does not explicitly indicate whether these specifications apply to:

    1. The I2C input signals (when the IC is receiving data as a slave device),
    2. The I2C output signals (when the IC is transmitting data or ACK as a slave device), or
    3. Both input and output signals.

    Could you kindly clarify whether these timing requirements apply to input signals, output signals, or both? 

    Thank you for your assistance. I look forward to your response.

    Best regards,

  • 0 in reply to Jimmy Chen
    TI__Genius 15700 points

    Hi Jimmy,

    The "I2C Timing Requirements" section defines the device requirements from the MCU, therefore all the specifications need to be met on the MCU's side. In this section, "Data in setup time" refers only to timing for when the device is receiving data. 

    Regards,
    Joel