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TM4C129ENCPDT: 25MHz Crystal Selection

Nishitha Chandrasekar
Intellectual 700 points
Part Number: TM4C129ENCPDT

Hi Charle sir,

Thank you very much for my previous doubts. it has been solved 

I have a doubt related to crystal . I have verified the datasheet for TM4C129NCPDT. While using the ethernet connection required 25MHz crystal with +/- 50ppm. In that thing whether both frequency tolerance and frequency stability has 50ppm or there is a difference??. If difference in tolerance and stability what will be the difference in ppm. Kindly explain. In below picture which i have to choose??

In TM4C129ENCPDT page no.1965 mentioned the 25MHz crystal details but i have an doubt in Rs value . If i selected the 500uW Max drive level crystal then what will be the Rs value??? because they had mentioned Rs value not exceed 500ohms but manufacturer mentioned 750ohms

Kindly clarify it 

  • 0
    TI__Guru**** 191296 points
    Hi,

    The tolerance is the allowable deviation from the specified frequency when looking at the crystal alone. Frequency Stability refers to the deviation from the nominal frequency encompassing other components in the loop.

    All I can say is that If you are choosing one the listed 25MHz crystals then they are simulated by TI to be working. If you are choosing crystals from other vendors not listed then they should work if they have nearly identical crystal parameters and you use the recommended component values listed in the table.