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TMP100: Could not read TMP100

Part Number: TMP100
Other Parts Discussed in Thread: TCA9511A

Hi Team,

My customer is evaluating our TMP100 for their temperature sensing, and some times could not access the TMP100 via I2C after some times. Resetting the device by power off/on the device usually could read it again. Is there a possible scenario that the TMP100 could lock itself from I2C? During the failure that could not read the TMP100, the same I2C line could still access other devices?

Will there be any concern if this temp sensor board is plugged into the system during the I2C line is still communicating (with other devices)?

In datasheet, it mentioned about the General Call. What it means by "latch the status of their address pins"? And can we use the second byte of 00000110 to reset the device?

Regards,

SK Loo

  • Hi team,

    They are building the TMP100 in a small board and this small board will be hot plugged into the system. V+ is 3.3V.

    The failure (could not recognized and communicate with TMP100) occur during hot plug. When failed, re plug might recover.

    During hot plug, the I2C could be in the middle of communication as there are other devices in the same I2C line.

    Is there any requirement and design consideration for application that need hot plug (eg, min cap required at V+?).

    Regards

    SK Loo

  • Hi SK Loo,

    Thank you for your post.

    I2C was not really designed for hot-swappable communication. On connection, you are changing the bus capacitance in real time, and SDA and SCL are very likely to be effected by noise or transients. This could be leaving the TMP100 in an unknown state. If you attempt a general call reset during one of these stuck conditions, does it correct the device being stuck? 

    In order to function consistently, you should consider using a two-wire hot-swappable buffer such as the TCA9511A. This will resolve the electrical and timing problems of hot-swapping with I2C. 

    Best Regards,
    Brandon Fisher