2253 - LatticeECP3: I have a DCS feeding a PLL and when it switches in simulation my PLL loses lock.
The PLL simulation model will lose lock when there is a difference between the input and the feedback clocks. This is due to the difficulty in modelling the actual PLL hardware.
TN1178 recommends that you do not switch the input clock to the PLL as this can lead to a loss of lock condition during operation.