AN-793 Datasheet, PDF (1/8 Pages) Analog Devices – ESD/Latch-Up Considerations with iCoupler® Isolation Products

AN-793
APPLICATION NOTE
One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106 • Tel: [phone] • Fax: [phone] • www.analog.com
ESD/Latch-Up Considerations with iCoupler^® Isolation Products
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.
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