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TMP117: alert mode without cummunication with MCU

hanlu wu
Prodigy 10 points
Part Number: TMP117
Other Parts Discussed in Thread: TMP390

Tool/software:

Dear engineer,

my question is that we want to use the TMP117 temperature sensor in a situation that the MCU doesn't work.

It means that before our products are delivered to our customers, the TMP117 has been initialized with the certain high and low temperature threshold number by the MCU throught the I2C communication. After this initialization, the communication between the MCU and TMP117 need to be cut off, and the T sensor still can work without MCU just according to the initilized situation in a Alert mode.

when our products in a customer hand, everytime when the product is restarted or repowered, the TMP117 can keep the initialized state, and can work without the MCU support. it means the I2C communication just work at the very first time int the product line.

we want to know that if your TMP117 sensor can meet our requirement.

It is a little urgent. We hope a prompt reply.

Thank you very much.

  • 0
    TI__Mastermind 43785 points

    Hanlu,

    The TMP117 has nonvolatile memory behind its configuration registers. You can alter the limits and other settings that are used when the device powers on. This enables it to assert its Alert without MCU intervention. However:

    • In the Alert Mode (T/nA bit = 0), you must use an MCU to clear the Alert status when it is asserted. If you do not have an MCU, the Alert pin will be asserted until power cycle. The Alert pin will assert for both over-temperature and under-temperature events.
    • In the Therm Mode (T/nA bit = 1), the Alert will be asserted for over-temperature events only. It will not be asserted for under-temperature events. In this mode, the Low Temperature Limit acts as a hysteresis for the High Limit, and determines when the Alert pin will be de-asserted.

    Please refer to Figure 7-5 and Figure 7-6

    Our line of temperature switch products are designed for standalone operation. I recommend reviewing the TMP390 and other products in that category if TMP117 does not meet your needs. https://www.ti.com/sensors/temperature-sensors/temperature-switches/products.html

    thanks,

    ren