ST & T UPSD3212C - Manual (Page 131)

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uPSD3212A, uPSD3212C, uPSD3212CV
EMC CHARACTERISTICS
Susceptibility test are performed on a sample ba-
sis during product characterization.
Functional EMS (Electromagnetic
Susceptibility)
Based on a simple running application on the
product (toggling 2 LEDs through I/O ports), the
product is stressed by two electromagnetic events
until a failure occurs (indicated by the LEDs).
ESD. Electro-Static Discharge (positive and neg-
ative) is applied on all pins of the device until a
functional disturbance occurs. This test conforms
with the IEC 1000-4-2 Standard.
FTB. A burst of Fast Transient voltage (positive
and negative) is applied to V
DD
and V
SS
through a
100pF capacitor, until a functional disturbance oc-
curs. This test conforms with the IEC 1000-4-2
Standard.
A device reset allows normal operations to be re-
sumed. The test results are given in Table
106 ,
based on the EMS levels and classes defined in
Application Note AN1709.
Designing Hardened Software To Avoid Noise
Problems
EMC characterization and optimization are per-
formed at component level with a typical applica-
tion 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
the user’s application.
Software Recommendations. The software
flowchart must include the management of ‘run-
away’ conditions, such as:
–
Corrupted program counter
– Unexpected reset
– Critical data corruption (e.g., control registers)
Prequalification trials. Most of the common fail-
ures (unexpected reset and program counter cor-
ruption) can be reproduced by manually forcing a
low state on the RESET pin or the oscillator pins
for 1 second.
To complete these trials, ESD stress can be ap-
plied directly on the device over the range of spec-
ification values. When unexpected behavior is
detected, the software can be hardened to prevent
unrecoverable errors occurring (see Application
Note AN1015).
Absolute Maximum Ratings (Electrical
Sensitivity)
Based on three different tests (ESD, LU, and DLU)
and using specific measurement methods, the
product is stressed in order to determine its perfor-
mance in terms of electrical sensitivity. For more
details, refer to the Application Note AN1181.
Electro-Static Discharge (ESD). Electro-Static
discharges (a positive then a negative pulse sepa-
rated by 1 second) are applied to the pins of each
sample according to each pin combination. The
sample size depends on the number of supply pins
in the device (3 parts*(n+1) supply pin). The Hu-
man Body Model is simulated (see Table
107 ).
This test conforms to the JESD22-A114A Stan-
dard.
Table 106. EMS Test Results
Note: 1. Data based on characterization results, not tested in production.
Table 107. ESD Absolute Maximum Ratings
Note: 1. Data based on characterization results, not tested in production
Symbol Parameter Conditions
Level/
Class
(1)
V
FESD
Voltage limits to be applied on any I/O pin to
induce a functional disturbance V
DD
= 4V; T
A
= 25°C; f
OSC
= 40MHz;
WDT off conforms to IEC 1000-4-2
3C
Symbol Parameter Conditions Maximum Value
(1) Unit
V
ESD(HBM)
Electro-static discharge voltage (Human
Body Model)
T
A
= 25°C 2000 V