STM32F105xx, STM32F107xx
Electrical characteristics
Functional EMS (electromagnetic susceptibility)
While a simple application is executed on the device (toggling 2 LEDs through I/O ports). the
device is stressed by two electromagnetic events until a failure occurs. The failure is
indicated by the LEDs:
●
Electrostatic discharge (ESD) (positive and negative) is applied to all device pins until
a functional disturbance occurs. This test is compliant with the IEC 61000-4-2 standard.
●
FTB: A burst of fast transient voltage (positive and negative) is applied to V and V
DD
SS
through a 100 pF capacitor, until a functional disturbance occurs. This test is compliant
with the IEC 61000-4-4 standard.
A device reset allows normal operations to be resumed.
The test results are given in Table 31. They are based on the EMS levels and classes
defined in application note AN1709.
Table 31. EMS characteristics
Level/
Class
Symbol
Parameter
Conditions
VDD = 3.3 V, LQFP100, TA = +25 °C,
fHCLK = 75 MHz, conforms to
IEC 61000-4-2
Voltage limits to be applied on any I/O pin to
induce a functional disturbance
VFESD
2B
4A
Fast transient voltage burst limits to be
applied through 100 pF on VDD and VSS
pins to induce a functional disturbance
VDD = 3.3 V, LQFP100, TA = +25 °C,
fHCLK = 75 MHz, conforms to
IEC 61000-4-2
VEFTB
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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