32M Oscillator for nRF5340

[helen]

Hi Nordic,

        A important customer employ nRF5340 in their product, they are chosing the 32M crystal osciallor now.

        Form the SPEC of 5340, if we want to communicate with packet>200 bytes, the frequency tolerance of HFXO should be less than 30 ppm.

        The customer has a osciallor used before has the Frequency Tolerance of 20ppm, and Frequency shift by temperature 20ppm.

        So the custuomer wonder 20+20=40ppm, which is larger than 30ppm.

        I want to know, whether this way of evaluating is appropriate? 

        Will the osciallor satifies the design with nRF5340?

        The attachment is the SPEC of the osciallor, please help to have a look.

        Many thanks!

        Luffy.

XRCGB32M000F2P10R0.pdf

[ovrebekk]

Hi

Form the SPEC of 5340, if we want to communicate with packet>200 bytes, the frequency tolerance of HFXO should be less than 30 ppm.

If they are using the Bluetooth protocol this is correct. 

        So the custuomer wonder 20+20=40ppm, which is larger than 30ppm.

        I want to know, whether this way of evaluating is appropriate? 

        Will the osciallor satifies the design with nRF5340?

Yes, this is the correct way of estimating worst case total drift. On top of this you also need to take into account the aging factor, which for this crystal is 5ppm / year. 

In other words this crystal will not satisfy the requirement. 

Best regards
Torbjørn