Urgent: LFCLK in nRF51822 ??? Power rating ???

[Faizan]

My boards are getting manufactured and now i realised that:

I'm using lfclk crystal oscillator part no#: ST2012SB32768E0HPWBB is having power rating of 0.5μW, where as nRF datasheet suggest Max value to be of 1μW. ( P D,X32k Drive level. 1 μW N/A)

Will I be ok with same crystal oscillator or do i need to change it

[FormerMember]

Yes, I would recommend you to change crystal. The maximum "drive level" is the maximum power that the crystal should be able to handle while still working normally.

[Faizan]

Hi, Thanks for the quick reply. Can you please explain this in a bit detail. I'm confused why the crystal oscillator should be able to handle maximum drive level? For example: If a Power source can drive up to 10 mA of current at 3V, and if i connect a load whose maximum current rating is 1mA. That device would draw only 1mA of current but not more than that?? I hope this should apply to crystal oscillator too... `

Actually changing the crystal would require lot of effort now?? Can you please shed some light on this " What would happen if i don't change the crystal now and just uses 0.5uW?? I mean its side effects???"

Thanks and Regards, Faizna

[FormerMember]

I'm not an expert on crystal details, however, exceeding the crystal max drive level may damage some the long term reliability of the crystal. You can read more about crystals and maximum drive level by searching the internet.

Are you sure that you need an external 32 kHz crystal? On the nRF51822 there is an internal RC oscillator with a frequency tolerance of +/-250 ppm. BLE applications work for instance fine with the internal RC osillator.