SP3222EH_06 Datasheet, PDF (13/19 Pages) Sipex Corporation – 3.3V, 460 Kbps RS-232 Transceivers

RR_CC
DC Power
Source
SSWW11
RR_SS
CC_SS
SSWW22
Device
Under
Test
Figure 17. ESD Test Circuit for Human Body Model
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 situations such as
hand held systems, the ESD charge can be
directly discharged to the equipment from a
person already holding the equipment. The
current is transferred on to the keypad or the
serial port of the equipment directly and then
travels through the PCB and finally to the IC.
The circuit models in Figures 17 and 18
represent the typical ESD testing circuits used
for all three methods. The C_S is initially charged
with the DC power supply when the first
switch (SW1) is on. Now that the capacitor is
charged, the second switch (SW2) is on while
SW1 switches off. The voltage stored in the
capacitor is then applied through R_S, the current
limiting resistor, onto the device under test
(DUT). In ESD tests, the SW2 switch is pulsed
so that the device under test receives a duration
of voltage.
R_CC
DC Power
Source
SW1
Contact-Discharge Module
R_SS
R_V
SW2
C_SS
Device
Under
Test
RS and RV add up to 330Ωffor IEC1000-4-2.
Figure 18. ESD Test Circuit for IEC1000-4-2
Date: 1/18/06
SP3222EH/3232EH 3.3V, 460 Kbps RS-232 Transceivers
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© Copyright 2006 Sipex Corporation