Datasheet

Electrical characteristics STM32F334x4 STM32F334x6 STM32F334x8
64/121 DocID025409 Rev 8
6.3.6 Wakeup time from low-power mode
The wakeup times given in Table 34 are measured starting from the wakeup event trigger up
to the first instruction executed by the CPU:
• For Stop or Sleep mode: the wakeup event is WFE.
• WKUP1 (PA0) pin is used to wake up from Standby, Stop and Sleep modes.
All timings are derived from tests performed under ambient temperature and V
DD
supply
voltage conditions summarized in
Table 19.
6.3.7 External clock source characteristics
High-speed external user clock generated from an external source
In bypass mode the HSE oscillator is switched off and the input pin is a standard GPIO. The
external clock signal has to respect the I/O characteristics in
Section 6.3.14. However, the
recommended clock input waveform is shown in Figure 14.
Table 34. Low-power mode wakeup timings
Symbol Parameter Conditions
Typ. @VDD, V
DD
= V
DDA
Max. Unit
2.0 V 2.4 V 2.7 V 3 V 3.3 V 3.6 V
t
WUSTOP
Wakeup from
Stop mode
Regulator in
run mode
4.3 4.1 4.0 3.9 3.8 3.7 4.5
µs
Regulator in
low-power
mode
7.8 6.7 6.1 5.9 5.5 5.3 9
t
WUSTANDBY
(1)
Wakeup from
Standby mode
LSI and
IWDG OFF
74.4 64.3 60.0 56.9 54.3 51.1 103
t
WUSLEEP
Wakeup from
Sleep mode
-6-
CPU
clock
cycles
1. Data based on characterization results, not tested in production.
Table 35. Wakeup time using USART
(1)
Symbol Parameter Conditions Typ Max Unit
tWUUSART
Wakeup time needed to calculate
the maximum USART baudrate
allowing to wake up from stop
mode when USART clock source is
HSI
Stop mode with main
regulator in low
power mode
- 13.125
µs
Stop mode with main
regulator in run
mode
- 3.125
1. Guaranteed by design.
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