STM32F401CB Datasheet, PDF (86/134 Pages) STMicroelectronics – Up to 81 I/O ports with interrupt capability

Electrical characteristics
STM32F401xB STM32F401xC
Table 48. EMS characteristics for LQFP100 package
Symbol
Parameter
Conditions
V_FESD
V_EFTB
Voltage limits to be applied on any I/O pin
to induce a functional disturbance
V_DD = 3.3 V, LQFP100, WLCSP49,
T_A = +25 °C, f_HCLK = 84 MHz,
conforms to IEC 61000-4-2
Fast transient voltage burst limits to be
applied through 100 pF on V_DD and V_SS
pins to induce a functional disturbance
V_DD = 3.3 V, LQFP100, WLCSP49,
T_A = +25 °C, f_HCLK = 84 MHz,
conforms to IEC 61000-4-4
Level/
Class
2B
4A
When the application is exposed to a noisy environment, it is recommended to avoid pin
exposition to disturbances. The pins showing a middle range robustness are: PA0, PA1,
PA2, on LQFP100 packages and PDR_ON on WLCSP49.
As a consequence, it is recommended to add a serial resistor (1 kΩ maximum) located as
close as possible to the MCU to the pins exposed to noise (connected to tracks longer than
50 mm on PCB).
Designing hardened software to avoid noise problems
EMC characterization and optimization are performed at component level with a typical
application environment and simplified MCU software. It should be noted that good EMC
performance is highly dependent on the user application and the software in particular.
Therefore it is recommended that the user applies EMC software optimization and
prequalification tests in relation with the EMC level requested for his application.
Software recommendations
The software flowchart must include the management of runaway conditions such as:
• Corrupted program counter
• Unexpected reset
• Critical Data corruption (control registers...)
Prequalification trials
Most of the common failures (unexpected reset and program counter corruption) can be
reproduced by manually forcing a low state on the NRST pin or the Oscillator pins for 1
second.
To complete these trials, ESD stress can be applied directly on the device, over the range of
specification values. When unexpected behavior is detected, the software can be hardened
to prevent unrecoverable errors occurring (see application note AN1015).
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