17.6.7 Digital Frequency Locked Loop (DFLL48M) Operation
The DFLL48M can operate in both open-loop mode and closed-loop mode. In closed-loop mode, a low-frequency clock with high accuracy can be used as the reference clock to get high accuracy on the output clock (CLK_DFLL48M).
The DFLL48M can be used as a source for the generic clock generators, as described in the GCLK – Generic Clock Controller.