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TMP122: SPI frequency

Adrian Ymeraj
Expert 3760 points
Part Number: TMP122
Other Parts Discussed in Thread: TMP124

Hello team,

one of my customers is redesigning a board and they are looking for a temperature sensor in the range -20 + 100 °C via SPI.

They saw the TMP122 and 124 devices but couldn't find the max SPI frequency allowed; do you have this information?

Do we have other devices in that range of temperatures and that can support SPI frequencies between of 16 and  30 Mhz ?

Thank you in advance.

Best regards,

Adrian

  • 0
    TI__Guru**** 244380 points
    Hello Adrian,

    The TMP122 and TMP124 provide only the minimum SCK period of 100 ns which amounts 10 MHz. Any faster timing than that would require to construct the timing path.

    Max Clock Period = Tout_delay + Tpropagation + Tsetup

    For the TMP122 the Tout_delay is max 30 ns which leaves Tpropagation + Tsetup of 70 ns. Depending on the MCU selected and the board layout whatever is the budget left can be used to increase the clock rate. As an example of Tpropagation + Tsetup = 30 ns, then we have a slack of 40 ns

    In such a case the maximum SCK is 100 ns - 40 ns = 60 ns or ~ 16 MHz.