LFSYNTH additional current and accuracy

[rgrr2]

Hi

in our device, HFXO is running permanently.  There is an external LFXO running permanently as well.

Now I'm wondering what would be the additional current draw if we switch from NRF_CLOCK_LF_SRC_XTAL to NRF_CLOCK_LF_SRC_SYNTH.  Any data available about this?

Because our application depends on an accurate LFCLK: how actually is LFSYNTH generated from HFCLK?

Thanks for help

Hardy

[Simonr]

Hi Hardy

According to the PS, the HFXO clock consumes 250µA by default and adding the LF SYNTH (specced at 100µA run current) you'd get ~350µA there. The LFXO will only consume ~0.25µA so the difference between the two would be almost ~99µA seeing as the HFXO is running regardless.

As for the LFSYNT accuracy, I'll need more details to know what you've got running that uses the HFXO as well and ask one of our experts what sharing the HFXO will have to say for the initial 8ppm + the HFXO tolerance that is stated in the spec. The LFXO is rated at a frequency tolerance of +-250ppm.

Best regards,

Simon

[rgrr2]

Hi Simon

thanks for the information.  Because current consumption is essential in my application: where can I find those 100uA in the PS?

Regards

Hardy