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Original question:

TMP117: Suggested DSBGA layout techniques ?

TMP117: CC/OS mode and ALERT

Hector Chen
Intellectual 380 points
Part Number: TMP117

Hi Team,

Because using OS mode will enter shutdown mode (the device powers down all active circuitry), we need to rely on ALERT to know when to read the temperature.

In CC mode, can we read temperature register whenever we want? 

Thanks.

  • 0
    TI__Mastermind 42025 points

    Hi Hector,

    While in shutdown mode, the temperature is not measured. ALERT is not updated in shutdown mode. Shutdown is the lowest power mode; it is effectively off.

    Yes, you can read temperature register whenever you want in either mode.

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Intellectual 380 points

    Hi Ren,

    Do you mean we read temperature register in OS mode whenever we want?

    If OS mode will enter shutdown mode, how do we read the temperature register in shutdown?

    Thanks.

    Hector 

  • 0 in reply to Hector Chen
    TI__Mastermind 42025 points

    You can read any register whenever you want. The temperature register will always contain the last temperature measurement. New measurements will not be started automatically while MOD = 01b in the Configuration register. See page 26. If you write MOD=11b, a single measurement will be started, and the device will go to shutdown (MOD=01b) after the measurement completes. 

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Intellectual 380 points

    Hi Ren,

    Let me summarize my understanding based on the discussion and datasheet.

    1. We can read any register whenever we want 

    2. The differences between OS mode and CC mode are 

    • OS mode is no averaging (AVG[1:0]= 00 only)
    • CC mode can work with AVG[1:0]=00/01/10/11
    • CC mode will enter standby 
    • OS mode will enter shutdown (even in shutdown mode, we still can read any registers)

    Thanks.

  • 0 in reply to Hector Chen
    TI__Mastermind 42025 points

    Hi Hector,

    Both OS and CC support averaging. Averaging increases the measurement time in either mode. Some CC modes target a refresh rate which is not possible with all averaging modes. This doesn't make those settings invalid; Table 7 explains what happens. 

    It's not explicitly stated in the datasheet, but Table 7 also explains what happens to measurement time in OS mode. When averaging is disabled (AVG=00,) the measurement time is 15.5ms. Measurement time increases to 8x, 32x, 64x as you move to the right in the first row of Table 7. 

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Intellectual 380 points

    Hi Ren,

    Thanks,

    Both modes support averaging. What are the advantages of using CC mode?

    OS can support averaging and provide lower power consumption than CC mode which can reduce the self-heating effect.

    I still don't understand what differences between the two modes are?

    Do any benefits users select to use CC mode?

    Thanks.

  • 0 in reply to Hector Chen
    TI__Mastermind 42025 points

    Hi Hector,

    CC is the default mode and is more convenient to use. You can read the temperature register at any time to get the most recent temperature measurement. To use OS, you must trigger a measurement to start, wait for it to complete, and then read the result.

    thanks,

    ren