STM32H7B3II datasheet(115/238 Pages) STMICROELECTRONICS

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6.3.13

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 60. EMS characteristics. They are based on the EMS levels and classes

defined in application note AN1709.

Table 60. 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, LQFP144, frcc_cpu_ck =

216 MHz, 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

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

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).

Electromagnetic Interference (EMI)

The electromagnetic field emitted by the device are monitored while a simple application, executing EEMBC code,

is running. This emission test is compliant with SAE IEC61967-2 standard which specifies the test board and the

pin loading.

STM32H7B3xI

Operating conditions

DS13139 - Rev 8

page 115/238

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