Datasheet

Electrical characteristics STM32F401xD STM32F401xE
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6.3.2 VCAP1/VCAP2 external capacitors
Stabilization for the main regulator is achieved by connecting external capacitor C
EXT
to the
VCAP1 and VCAP2 pin. For packages supporting only 1 VCAP pin, the 2 CEXT capacitors
are replaced by a single capacitor.
C
EXT
is specified in Table 16.
Figure 20. External capacitor C
EXT
1. Legend: ESR is the equivalent series resistance.
1. Applicable only when the code is executed from Flash memory. When the code is executed from RAM, no wait state is
required.
2. Thanks to the ART accelerator and the 128-bit Flash memory, the number of wait states given here does not impact the
execution speed from Flash memory since the ART accelerator allows to achieve a performance equivalent to 0 wait state
program execution.
3. Refer to for frequencies vs. external load.
4. V
DD
/V
DDA
minimum value of 1.7 V, with the use of an external power supply supervisor (refer to Section 3.14.2: Internal
reset OFF).
5. Prefetch is not available. Refer to AN3430 application note for details on how to adjust performance and power.
6. The voltage range for the USB full speed embedded PHY can drop down to 2.7 V. However the electrical characteristics of
D- and D+ pins will be degraded between 2.7 and 3 V.
Table 16. VCAP1/VCAP2 operating conditions
(1)
1. When bypassing the voltage regulator, the two 2.2 µF V
CAP
capacitors are not required and should be
replaced by two 100 nF decoupling capacitors.
Symbol Parameter Conditions
CEXT
Capacitance of external capacitor with available
VCAP1 and VCAP2 pins
2.2 µF
ESR
ESR of external capacitor with available VCAP1 and
VCAP2 pins
< 2 Ω
CEXT
Capacitance of external capacitor with a single VCAP
pin available
4.7 µF
ESR
ESR of external capacitor with a single VCAP pin
available
< 1 Ω
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