Mr Tromp -
- What is your power up sequence?
- Have you reference the power-up sequence on page 51 of the datasheet?
- What value are you using for the VCAP1 capacitance?
In addition to the datasheet power up sequence, you might want to check the relationship between the RESET pulse low and voltage on VCAP1. Ideally, VCAP1 voltage should be >1.1V before RESET is pulsed or 218 tclk after the supplies stabilize, whichever is longer)
If you want to include a scope shot of your startup, we can offer some additional suggestions.