Datasheet

Functional overview STM32F427xx STM32F429xx
30/239 DocID024030 Rev 10
In regulator OFF mode, the following features are no more supported:
• PA0 cannot be used as a GPIO pin since it allows to reset a part of the V
12
logic power
domain which is not reset by the NRST pin.
• As long as PA0 is kept low, the debug mode cannot be used under power-on reset. As
a consequence, PA0 and NRST pins must be managed separately if the debug
connection under reset or pre-reset is required.
• The over-drive and under-drive modes are not available.
• The Standby mode is not available.
Figure 8. Regulator OFF
The following conditions must be respected:
• V
DD
should always be higher than V
CAP_1
and V
CAP_2
to avoid current injection
between power domains.
• If the time for V
CAP_1
and V
CAP_2
to reach V
12
minimum value is faster than the time for
V
DD
to reach 1.7 V, then PA0 should be kept low to cover both conditions: until V
CAP_1
and V
CAP_2
reach V
12
minimum value and until V
DD
reaches 1.7 V (see Figure 9).
• Otherwise, if the time for V
CAP_1
and V
CAP_2
to reach V
12
minimum value is slower
than the time for V
DD
to reach 1.7 V, then PA0 could be asserted low externally (see
Figure 10).
• If V
CAP_1
and V
CAP_2
go below V
12
minimum value and V
DD
is higher than 1.7 V, then a
reset must be asserted on PA0 pin.
Note: The minimum value of V
12
depends on the maximum frequency targeted in the application
(see Table 17: General operating conditions).
DL9
%<3$66B5(*
9
&$3B
9
&$3B
3$
9
9
''
1567
9
''
$SSOLFDWLRQUHVHW
VLJQDORSWLRQDO
([WHUQDO9
&$3B
SRZHU
VXSSO\VXSHUYLVRU
([WUHVHWFRQWUROOHUDFWLYH
ZKHQ9
&$3B
0LQ9


9
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.