AN-793

APPLICATION NOTE

One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106 • Tel: 781/329-4700 • Fax: 781/461-3113 • www.analog.com

ESD/Latch-Up Considerations with

by Rich Ghiorse

INTRODUCTION

Analog Devices

iCoupler products offer an alternative iso-

lation solution to optocouplers with superior integration,

performance, and power consumption characteristics. An

iCoupler isolation channel consists of CMOS input and

output circuits and a chip scale transformer (see Figure 1).

Because the

iCoupler employs CMOS technology, it can

be more vulnerable to latch-up or electrostatic discharge

(ESD) damage than an optocoupler when subjected to

system-level ESD, surge voltage, fast transient, or other

overvoltage conditions.

Figure 1. ADuM140x Quad Isolator

This application note provides guidance for avoiding

these problems. Examples are presented for various

system-level test configurations showing mechanisms

that may impact performance. For each example recom-

mended solutions are given.

Later this year, Analog Devices is introducing hardened

versions of most

iCoupler products that will have

improved immunity to latch-up and electrical overstress

(EOS). This new product family, the ADuM3xxx series,

will be pin-compatible with the existing ADuM1xxx

series products and will offer identical performance

specifications. Both product families will continue to

be made available.

Components vs. Systems

Simply put, a component is a single integrated device

with interconnects while a system is a nonintegrated

device built from several interconnected components. In

almost all cases the distinction between a component

and a system is obvious. However, the differences

between component and system tests may not be

so obvious. Further, component specifications may

not directly indicate how a device will perform in

system-level testing. ESD testing is a good example

of this.

ESD, surge, burst, and fast transient events are facts of

life in electronic applications. These events generally

consist of high voltage, short duration spikes applied

directly or indirectly to a device. These events arise

from interaction of the device to real-world phenomena,

such as human contact, ac line perturbations, lightning

strikes, or common-mode voltage differences between

system grounds.

Component-level ESD testing is most useful in deter-

mining a device’s robustness to handling by humans

and automated assembly equipment prior and during

assembly into a system. Component-level ESD data is

less useful in determining a device’s robustness within

a system subjected to system-level ESD events. There

are two reasons for this.

•

System- and component-level ESD testing have

different objectives. Component-level testing seeks

to address conditions typically endured during com-

ponent handling and assembly. System-level testing

seeks to address conditions typically endured during

system operation.

•

The specific conditions a component is subjected

to during system-level testing can be a strong func-

tion of the board/module/system design in which it

resides. For example, long inductive traces between

a system and component ground can actually impose

a more severe voltage transient onto a component

than is imposed on the system at the test point.

REV. 0