Analog Devices ADSP-BF506F Hardware Reference Manual page 1206

Voltage Regulation Interface
If the external regulator for V
can be used to help the processor recover properly from it's hibernate
state. This signal may need to be inverted, as the processor's input should
be low-true in order to indicate a "power good" condition.
If the external regulator does not have a power-good output, the
should be driven to a fixed level (just below the desired operating voltage)
so that the pin voltage can be compared to V
PG
startup logic. This can be accomplished with an external resistor divider
from V
DDEXT
of 1M Ohm is sufficient to supply current to this
more current during hibernation, the
voltage source to the divider.
go high before the V
all cases, care should be taken to account for the min and max values of
V or V
DDEXT OH
the threshold that is compared internally to the rising value of V
signal the processor to start. The voltage at
that the V
DDINT
application.
25-12
DDINT
or any other fixed stable voltage. A divider with impedance
EXT_WAKE
voltage is applied by the external regulator. In
DDINT
for . The voltage applied to the
EXT_WAKE
value has risen to the desired voltage range for the
ADSP-BF50x Blackfin Processor Hardware Reference
has a power-good signal output, it
DDINT
input. To save even
PG
signal may be used as the
EXT_WAKE
is low during hibernation, but will
should be calculated such
PG
signal
PG
by the internal
pin is used as
PG
to
DDINT