There are multiple low frequency clock source options that
can be used on the BL5340 module:
·
The Internal 32.768 kHz RC oscillator (LFRC)
·
LFXO (32.768kHz crystal oscillator)
·
Low frequency (32.768 kHz) external source
o
A low swing clock
o
A rail-to-rail clock
·
LFSYNTH (32.768kHz Synthesized clock) from HFCLK (LFSYNTH)
The
datasheet provides information showing peak-to-peak amplitude for external low
swing clock.
Peak to Peak amplitude of 200mV to 1000mV is required when using a low swing, low frequency single rail oscillator. This is sometimes misinterpreted for cases using an external 32.768KHz crystal oscillator. An external 32.768KHz oscillator will typically have a swing of less than 200mV.