18.104.22.168. User Calibration
The I/O PLL must be recalibrated for any of the following conditions after device power up:
- Dynamic I/O PLL reconfiguration that changes the M or N counter settings is performed.
- Change of the reference clock frequency to the I/O PLL.
Recalibration is not necessary when using clock switchover to a secondary reference clock with a different frequency than the primary reference clock. The I/O PLL stores the calibration settings for both reference clocks after power-up calibration. For more information on recalibration methods, refer to the Recalibration Using .mif and the Recalibration Using Advanced Mode sections.
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