External oscillator vs DCO

Development Boards MicroMod
4

Wrt #2 in my first post, I found a TI app note that waits 18ms for a 3.58MHz xtal to stabilize (slaa123.pdf). And in the MSP430 user’s guide I found these steps to run switch the MCLK from DCO to XT2:

  1. Switch on the crystal oscillator

  2. Clear the OFIFG flag

  3. Wait at least 50 µs

  4. Test OFIFG, and repeat steps 1-4 until OFIFG remains cleared.

So 50 micro secs seems like an absolute minimum.

I think I’ll add an external xtal to my design just to measure the stabilization time.

So to update #2:

  1. Quickest time to come out of LPM3: ~6 microsec for DCO stable, 50us to 18ms for external HF xtal. DCO wins but need to confirm with some tests.

Cheers,

MH