Beaglebone power on reset question

I have noticed that sometimes Beaglebones will not start reliably when power is supplied from certain sources. This happens on multiple units. Further controlled investigations showed that if the rise time of the applied 5V was > ~500 micro-seconds, then start-up was unreliable. Is there a specification for the minimum required dV/dt, and if so where can I find it?

Best regards,


I have made no such specification.