FX2 (not FX2LP) requires crystal with the following characteristics:
■ Parallel resonant
■ Fundamental mode
■ Frequency Stability: ±100 ppm
■ 500-uW drive level
■ 20–33 pF (5% tolerance) load capacitors.
The part we use on our development board is the 20 pF version from ECS (ECS-240-20-4). We also place the 30 pF version, ECS-240-30-4.
Please note FX2 is obsolete and the replacement part is FX2LP.