The values for P, Q, R, and N’ are automatically calculated when using TI Pro-Clock™ software.9.2.2.3 Crystal Oscillator Start-upWhen the CDCE913/CDCEL913 is used as a crystal buffer, crystal oscillator start-up dominates the start-up timecompared to the internal PLL lock time. The following diagram shows the oscillator start-up sequence for a 27-MHz crystal input with an 8-pF load. The start-up time for the crystal is in the order of approximately 250 µscompared to approximately 10 µs of lock time. In general, lock time will be an order of magnitude less comparedto the crystal start-up time.