Datasheet

Table Of Contents
DocID022152 Rev 8 31/202
STM32F405xx, STM32F407xx Description
Standby mode, the SRAM and register contents are lost except for registers in the
backup domain and the backup SRAM when selected.
The device exits the Standby mode when an external reset (NRST pin), an IWDG reset,
a rising edge on the WKUP pin, or an RTC alarm / wakeup / tamper /time stamp event
occurs.
The standby mode is not supported when the embedded voltage regulator is bypassed
and the V
12
domain is controlled by an external power.
2.2.20 V
BAT
operation
The V
BAT
pin allows to power the device V
BAT
domain from an external battery, an external
supercapacitor, or from V
DD
when no external battery and an external supercapacitor are
present.
V
BAT
operation is activated when V
DD
is not present.
The V
BAT
pin supplies the RTC, the backup registers and the backup SRAM.
Note: When the microcontroller is supplied from V
BAT
, external interrupts and RTC alarm/events
do not exit it from V
BAT
operation.
When PDR_ON pin is not connected to V
DD
(internal reset OFF), the V
BAT
functionality is no
more available and V
BAT
pin should be connected to V
DD
.
2.2.21 Timers and watchdogs
The STM32F405xx and STM32F407xx devices include two advanced-control timers, eight
general-purpose timers, two basic timers and two watchdog timers.
All timer counters can be frozen in debug mode.
Table 4 compares the features of the advanced-control, general-purpose and basic timers.
Table 4. Timer feature comparison
Timer
type
Timer
Counter
resolution
Counter
type
Prescaler
factor
DMA
request
generation
Capture/
compare
channels
Complemen-
tary output
Max
interface
clock
(MHz)
Max
timer
clock
(MHz)
Advanced
-control
TIM1,
TIM8
16-bit
Up,
Down,
Up/down
Any integer
between 1
and 65536
Yes 4 Yes 84 168