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© Freescale Semiconductor, Inc., 2005. All rights reserved.
Freescale Semiconductor
Application Note
AN2764
Rev. 0, 06/2005
Improving the Transient Immunity
Performance of
Microcontroller-Based Applications
by: Ross Carlton, Greg Racino, John Suchyta
Freescale Semiconductor, Inc.
Introduction
Increased competition among appliance manufacturers, as well as market regulatory pressures, are
challenging original equipment manufacturers (OEMs) to reduce the cost of their products while ensuring
compatible operation in increasingly severe electro-magnetic environments. As a result of this focus on
cost control, implementing the necessary transient immunity protections to prevent appliance malfunction
due to transients on power and signal lines is becoming ever more challenging for the appliance designer.
Because traditional power supply designs and electro-magnetic interference (EMI) controls are sacrificed
for lower-cost solutions, the appliance designer must develop new techniques to meet applicable
regulatory electro-magnetic compatibility (EMC) requirements.
This application note discusses the effects of transient electrical disturbances on embedded
microcontrollers (MCUs) and suggests practical hardware and software design techniques that can
provide cost-effective protection for electrical fast transients (EFT), electrostatic discharge (ESD), and
other power line or signal line transients of short duration. Although this discussion is targeted at
appliance manufacturers, these principles also apply to applications in consumer, industrial, and
automotive electronics.
