1 Reply Latest reply on Mar 31, 2014 9:42 AM by MichaelF_56

    optional external oscillator for BCM20732S

      Can anyone shed light on why one would or wouldn't choose to use this?

       

      I'm looking at p8 of the BCM20732S datasheet, "32.768 kHz Oscillator (optional)"

       

      Thanks

       

      Tim

        • 1. Re: optional external oscillator for BCM20732S
          MichaelF_56

          My understanidng is that the Ext Osc is utilized when increased sleep clock accuracy (PPM) is needed.  Recall that as part of the connection event, the master and slave exchange sleep clock accuracy (PPM) and the accuracy is used to determine the uncertainty window of the slave device for the duration of the connection event. This means that more accurate clocks can actually save power.


          In addition, the module includes ability to wake from DEEP SLEEP after a configured time. Using the internal clock, it can wake anywhere from 64mS to ~36 Hrs. With external 32KHz xtal, 128mS - ~144 Hrs.