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October 2012 Doc ID 14310 Rev 3 1/42
AN2689
Application note
Protection of automotive electronics from electrical hazards,
guidelines for design and component selection
Introduction
Electronic equipment represents a large part of the automobiles of today. Although these
electronic modules bring much more comfort and security for the vehicle user, they also
bring significant concerns in terms of reliability regarding the automobile environment.
Because electronic modules are sensitive to electromagnetic disturbances (EMI),
electrostatic discharges (ESD) and other electrical disturbances (and automobiles are the
source of many such hazards), caution must be taken wherever electronic modules are
used in the automotive environment.
Several standards have been produced to model the electrical hazards that are currently
found in automobiles. As a result manufacturers and suppliers have to consider these
standards and have to add protection devices to their modules to fulfill the major obligations
imposed by these standards.
The objective of this document is to help electronic module designers with a protection
design approach for selecting the most suitable devices for typical applications depending
on the protection standard the electronic module has to meet.
Section 1 describes the electrical hazards considered in this document. Section 2 presents
a list of parameters to be taken into account before selecting possible protection devices.
Section 3 and Section 4 provide worked design examples, with design calculations, for
several protection solutions. Section 5 provides recommendations for the design of PCB
layout for improved solutions.
Transil is a trademark of STMicroelectronics.
www.st.com
