Does FX3 has any power sequence?
FX3 does not have any power up sequence. Make sure that all the power supplies are stable before RESET_N is asserted. It is assumed that all the power supplies will be stable within 1 ms RESET time. Therefore, it is recommended to maintain minimum 1 ms RESET time through the RC circuit. If it takes more than 1 ms to provide stable supplies on your design, the RESET time also need to be increased.