QAccording the Table 12 of the Rev.C datasheet, the "Outputs return to the input
state within 1us of VDD2 power restoration". However, I'm experiencing a delay
of about 70us with a VDD2 of 15V. Why?
AThere are actually two different starting delays, and you may not like how the
datasheet addressed this. The ~70µs is what we expect the part to do if it
passes the internal power on reset threshold which is pretty low, somewhere
around 2-3V. The 1 µs number is if the part just enters UVLO, then exits UVLO.
The logic table doesn't really show this.
All of our parts will have some delay on startup of the secondary side. The
older parts (ADuM3220 included) didn't originally express this in the
datasheet. We might go back and revisit the older datasheets and add some more
information in the future.