SP2209E Datasheet, PDF (11/17 Pages) Sipex Corporation – High ESD Dual Port RS-232 Transceiver

ESD Tolerance
The SP2209E device incorporates rug-
gedized ESD cells on all driver output and
receiver input pins. The ESD structure
is improved over our previous family for
more rugged applications and environ-
ments sensitive to electro-static dis-
charges and associated transients. The
improved ESD tolerance is at least +15kV
without damage nor latch-up.
There are different methods of ESD testing
applied:
a) MIL-STD-883, Method 3015.7
b) IEC 61000-4-2 Air-Discharge
c) IEC 61000-4-2 Direct Contact
The Human Body Model has been the
generally accepted ESD testing method
for semi-conductors. This method is also
specified in MIL-STD-883, Method 3015.7
for ESD testing. The premise of this ESD test
is to simulate the human body’s potential to
store electro-static energy and discharge it
to an integrated circuit. The simulation is
performed by using a test model as shown
in Figure 10. This method will test the IC’s
capability to withstand an ESD transient
during normal handling such as in manu-
facturing areas where the IC's tend to be
handled frequently.
The IEC-61000-4-2, formerly IEC801-2, is
generally used for testing ESD on equipment
and systems. For system manufacturers,
they must guarantee a certain amount of
ESD protection since the system itself is
exposed to the outside environment and
human presence. The premise with IEC
R_C
DESCRIPTION
61000-4-2 is that the system is required to
withstand an amount of static electricity when
ESD is applied to points and surfaces of the
equipment that are accessible to personnel
during normal usage. The transceiver IC
receives most of the ESD current when the
ESD source is applied to the connector pins.
The test circuit for IEC 61000-4-2 is shown
on Figure 11. There are two methods within
IEC 61000-4-2, the Air Discharge method
and the Contact Discharge method.
With the Air Discharge Method, an ESD
voltage is applied to the equipment under
test (EUT) through air. This simulates an
electrically charged person ready to connect
a cable onto the rear of the system only to
find an unpleasant zap just before the person
touches the back panel. The high energy
potential on the person discharges through
an arcing path to the rear panel of the system
before he or she even touches the system.
This energy, whether discharged directly or
through air, is predominantly a function of the
discharge current rather than the discharge
voltage. Variables with an air discharge such
as approach speed of the object carrying the
ESD potential to the system and humidity
will tend to change the discharge current.
For example, the rise time of the discharge
current varies with the approach speed.
The Contact Discharge Method applies the
ESD current directly to the EUT. This method
was devised to reduce the unpredictability
of the ESD arc. The discharge current rise
time is constant since the energy is directly
transferred without the air-gap arc. In situ-
ations such as hand held systems, the ESD
charge can be directly discharged to the
R_S
DC Power
Source
SW1
C_S
SW2
Device
Under
Test
Figure 10. ESD Test Circuit for Human Body Model
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
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SP2209E_100_071612