can instable VDD cause nrf51 not turning on

[makouda]

I have issue with nrf51 booting, i noticed that sometimes when i plug the power to (VDD and GND) the system dosent turn on at al.

1 - how does the system the whole system turn on? (just by receiving the first impulse?)

2 - can the system not turn on when receiving instable impulses at the begining then stable current?

[Ole Bauck]

The supply rise time (0V to VDD) needs to be less than 100ms for the on-chip power-on reset circuitry to function correctly, see Product Specification table 20 in chapter 7. May this be the case?