Datasheet

Functional EMS (electromagnetic susceptibility)10.3.12.1
While executing a simple application (toggling 2 LEDs through I/O ports), the product is
stressed by two electromagnetic events until a failure occurs (indicated by the LEDs).
•
FESD: Functional electrostatic discharge (positive and negative) is applied on all pins of
the device until a functional disturbance occurs. This test conforms with the IEC 61000-4-2
standard.
•
FTB: A burst of fast transient voltage (positive and negative) is applied to V
DD
and V
SS
through a 100 pF capacitor, until a functional disturbance occurs. This test conforms with
the IEC 61000-4-4 standard.
A device reset allows normal operations to be resumed. The test results are given in the table
below based on the EMS levels and classes defined in application note AN1709 (EMC design
guide for STMicrocontrollers).
Designing hardened software to avoid noise problems10.3.12.2
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
recovered by applying 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 (Software techniques
for improving microcontroller EMC performance).
Table 48: EMS data
Level/
class
ConditionsParameterSymbol
2/B
(1)
V
DD
= 5 V, T
A
= 25 °C, f
MASTER
= 16 MHz,
conforming to IEC 1000-4-2
Voltage limits to be
applied on any I/O pin to
induce a functional
disturbance
V
FESD
4/A
(1)
V
DD
= 5 V, T
A
= 25 °C ,f
MASTER
= 16
MHz,conforming to IEC 1000-4-4
Fast transient voltage
burst limits to be applied
through 100 pF on V
DD
V
EFTB
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STM8S105xxElectrical characteristics