STM32F401CD Datasheet, PDF (79/135 Pages) STMicroelectronics – Up to 12 communication interfaces

STM32F401xD STM32F401xE
Electrical characteristics
Note:
series combination of C_L1 and C_L2. PCB and MCU pin capacitance must be included (10 pF
can be used as a rough estimate of the combined pin and board capacitance) when sizing
C_L1 and C_L2.
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.
Figure 24. Typical application with an 8 MHz crystal
Note:
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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).
Table 38. LSE oscillator characteristics (f_LSE = 32.768 kHz) ⁽¹⁾
Symbol
Parameter
Conditions
Min Typ Max Unit
R_F
Feedback resistor
-
18.4 -
MΩ
I_DD
LSE current consumption
-
-
1
µA
G_m_crit_max Maximum critical crystal g_m
Startup
-
- 0.56 µA/V
t_SU(LSE)(2) startup time
V_DD is stabilized
-
2
-
s
1. Guaranteed by design, not tested in production.
2.
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enabled (by software) to a stabilized
by characterization and not tested in
production. It is measured for a standard crystal resonator and it can vary significantly with the crystal
manufacturer.
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.
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