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EMC DESIGN GUIDE FOR ST MICROCONTROLLERS

2 EMC CHARACTERIZATION OF ST MICROCONTROLLERS

2.1 ELECTROMAGNETIC SUSCEPTIBILITY (EMS)

Two different type of tests are performed:

s

Tests with device power-supplied (Functional EMS tests & Latch-up): The device behaviour

is monitored during the stress.

s

One test with device not powered supplied (Absolute Electrical Sensitivity): The device

functionality and integrity is checked on tester after stress.

2.1.1 Functional EMS test

Functional Tests are performed to measure the robustness of ST Microcontrollers running in

an application. Based on a simple program (toggling 2 LEDs through I/O ports), the product is

stressed by 2 different EMC events until a run-away condition (failure) occurs.

2.1.1.1 Functional ElectroStatic Discharge Test (F_ESD Test)

This test is performed on any new microcontroller devices.Each pin is tested individually with

a single positive or negative electrical discharge.This allows failures investigations inside the

chip and further application recommendations to protect the concerned Microcontroller sensi-

tive pins against ESD.

High static voltage has both natural and man made origins. Some specific equipment can re-

produce this phenomenon in order to test the device under real conditions. Equipment, test

sequence and standards are described here below.

ST Microcontroller F_ESD qualification test uses standards given in Table 1 as reference.

Table 1. ESD standards

AEC-Q100-REUE is the Automotive controlling document.

F_ESD tests uses a signal source and a power amplifier to generate a high level field into The

Microcontroller. The insulator is using a conical tip. This tip is placed on the Device or Equip-

ment Under Test (DUT or EUT) and an electrostatic discharge is applied (see Figure 1.).

EUROPEAN NORM

INTERNATIONAL NORM

DESCRIPTION

EN 61000-4-2

IEC 1000-4-2

Conducted ESD test