28.6.3 PLL Unlock

Each PLL has an unlock flag. It is recommended to set the UNLOCK interrupt by setting the corresponding PMC_PLL_IER.UNLOCK bit to quickly detect a failure on PLL clock generation.

The rise of a PLL unlock signal implies a failure in the normal operation of the PLL (input clock loss, for example). In this case, the PLL keeps operating but stops trying to lock the input clock. A manual clock switching to a stable clock should be performed to ensure CPU_CLK integrity.

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