Datasheet

DocID026289 Rev 6 85/149
STM32F411xC STM32F411xE Electrical characteristics
123
Figure 24. Typical application with an 8 MHz crystal
1. R
EXT
value depends on the crystal characteristics.
Low-speed external clock generated from a crystal/ceramic resonator
The low-speed external (LSE) clock can be supplied with a 32.768 kHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on
characterization results obtained with typical external components specified in Table 38. In
the application, the resonator and the load capacitors have to be placed as close as
possible to the oscillator pins in order to minimize output distortion and startup stabilization
time. Refer to the crystal resonator manufacturer for more details on the resonator
characteristics (frequency, package, accuracy).
The LSE high-power mode allows to cover a wider range of possible crystals but with a cost
of higher power consumption.
Note: For information on selecting the crystal, refer to the application note AN2867 “Oscillator
design guide for ST microcontrollers” available from the ST website www.st.com.
For information about the LSE high-power mode, refer to the reference manual RM0383.
Table 38. LSE oscillator characteristics (f
LSE
= 32.768 kHz)
(1)
1. Guaranteed by design.
Symbol Parameter Conditions Min Typ Max Unit
R
F
Feedback resistor - - 18.4 - MΩ
I
DD
LSE current
consumption
Low-power mode
(default)
--1
µA
High-drive mode - - 3
G
m
_crit_max
Maximum critical crystal
g
m
Startup, low-power mode - - 0.56
µA/V
Startup, high-drive mode - - 1.50
t
SU(LSE)
(2)
2. t
SU(LSE)
is the startup time measured from the moment it is enabled (by software) to a stabilized
32.768 kHz oscillation is reached. This value is guaranteed by characterization. It is measured for a
standard crystal resonator and it can vary significantly with the crystal manufacturer.
startup time V
DD
is stabilized - 2 - s
DL
26&B287
26&B,1
I
+6(
&
/
5
)
670)
0+]
UHVRQDWRU
5HVRQDWRUZLWK
LQWHJUDWHGFDSDFLWRUV
%LDV
FRQWUROOHG
JDLQ
5
(;7


&
/
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.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.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.