STM32MP157A datasheet(163/259 Pages) STMICROELECTRONICS

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DS12504 Rev 5

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STM32MP157A/D

Electrical characteristics

237

6.3.14

EMC characteristics

Susceptibility tests are performed on a sample basis during device characterization.

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 VDD and VSS

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 47. They are based on the EMS levels and classes

defined in application note AN1709 available from the ST website www.st.com.

As a consequence, it is recommended to add a serial resistor (1 kΩ) 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...)

1. Guaranteed by design.

Table 47. EMS characteristics

Symbol

Parameter

Conditions

Level/

Class

VFESD

Voltage limits to be applied on any I/O pin to induce a

functional disturbance

VDD = 3.3 V, TA = +25 °C, LFBGA448,

Fmpuss_ck = 650 or 800 MHz,

Fmcu_ck = 209 MHz,

M4 core not running,

conforms to IEC 61000-4-2

VFTB

Fast transient voltage burst limits to be applied

through 100 pF on VDD and VSS pins to induce a

functional disturbance

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