SP3222EEY/TR Exar, SP3222EEY/TR Datasheet - Page 12

• Manufacturer Part Number: SP3222EEY/TR
• Description: RS-232 Interface IC RS232 Transceiver 3-5.5V 2-drvr/2-rcvr
• Manufacturer: Exar

Specifications of SP3222EEY/TR

• Product Category: RS-232 Interface IC
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-20
• Function: Transceiver
• Number Of I/os: 4

ESD TOLERANCE
The SP3222E/SP3232E series incorpo-
rates ruggedized ESD cells on all driver
output and receiver input pins. The ESD
structure is improved over our previous
family for more rugged applications and
environments sensitive to electro-static
discharges and associated transients. The
improved ESD tolerance is at least +15kV
without damage nor latch-up.
There are different methods of ESD testing
applied:
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 16. This method will test the IC’s
capability to withstand an ESD transient
during normal handling such as in manu-
facturing areas where the ICs 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 pres-
ence. The premise with IEC61000-4-2 is that
Figure 16. ESD Test Circuit for Human Body Model
a) MIL-STD-883, Method 3015.7
b) IEC61000-4-2 Air-Discharge
c) IEC61000-4-2 Direct Contact
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
DC Power
Source
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C
SW1
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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 IEC61000-4-2 is shown on Figure 17.
There are two methods within IEC61000-4-2,
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
SW2
SP3222E/SP3232E_101_031413
Device
Under
Test
DESCRIPTION