ST72321B STMICROELECTRONICS [STMicroelectronics], ST72321B Datasheet - Page 152

• Manufacturer Part Number: ST72321B
• Description: 64/44-pin 8-bit MCU with 32 to 60K Flash/ROM, ADC, five timers, SPI, SCI, I2C interface
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

12.7 EMC CHARACTERISTICS
Susceptibility tests are performed on a sample ba-
sis during product characterization.
12.7.1 Functional EMS (Electro Magnetic
Susceptibility)
Based on a simple running application on the
product (toggling 2 LEDs through I/O ports), the
product is stressed by two electro magnetic events
until a failure occurs (indicated by the LEDs).
■
■
A device reset allows normal operations to be re-
sumed. The test results are given in the table be-
low based on the EMS levels and classes defined
in application note AN1709.
12.7.1.1 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
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Symbol
ESD: Electro-Static Discharge (positive and
negative) 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
a 100pF capacitor, until a functional disturbance
occurs. This test conforms with the IEC 1000-4-
4 standard.
V
V
FESD
FFTB
Voltage limits to be applied on any I/O pin to induce a
functional disturbance
Fast transient voltage burst limits to be applied
through 100pF on V
tional disturbance
DD
Parameter
DD
and V
and V
DD
pins to induce a func-
SS
through
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 manage-
ment 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 repro-
duced by manually forcing a low state on the RE-
SET 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
specification values. When unexpected behaviour
is detected, the software can be hardened to pre-
vent unrecoverable errors occurring (see applica-
tion note AN1015)
.
All Flash and ROM devices, V
T
1000-4-2
32K Flash device LQFP44/LQFP32, :
V
forms to IEC 1000-4-4
48/60K Flash and all ROM devices,
V
forms to IEC 1000-4-4
A
DD
DD
=+25°C, f
=5V, T
=5V, T
A
A
=+25°C, f
=+25°C, f
OSC
Conditions
=8 MHz, conforms to IEC
OSC
OSC
=8 MHz, con-
=8 MHz, con-
DD
=5V,
Level/
Class
3B
3B
4A