SP3220E_05 Datasheet, PDF (15/21 Pages) Sipex Corporation – +3.0V to +5.5V RS-232 Driver/Receiver Pair

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
transfered without the air-gap arc. In situa-
tions such as hand held systems, the ESD
charge can be directly discharged to the
equipment from a person in contact with the
equipment. The current is transferred on to
the keypad or the serial port of the equip-
ment directly and then travels through the
PCB and finally to the IC.
RR_CC
The circuit models in Figure 20 and 21
represent the typical ESD testing circuits
used for all three methods. The C is initially
S
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 ap-
plied through R_S, the current limiting resis-
tor, onto the device under test (DUT). In
ESD tests, the SW2 switch is pulsed so that
the device under test recives a duration of
voltage.
Contact-Discharge Module
R_SS
R_V
DC Power
Source
SW1
C_SS
SW2
Device
Under
Test
Figure 21. ESD Test Circuit for IEC1000-4-2
RS and RV add up to 3301 for IEC1000-4-2.
For the Human Body Model, the current
limiting
tor (C_S)
raerseis1t.o5rk(₁R_{Sa)nadn1d0t0hpeFs,oruerscpeeccatipvaeclyi-.}
For IEC-1000-4-2, the current limiting resis-
tor (RS) and the source capacitor (CS) are
3301 and 150pF, respectively.
The higher CS value and lower RS value in
the IEC1000-4-2 model are more stringent
than the Human Body Model. The larger
storage capacitor injects a higher voltage to
the test point when SW2 is switched on. The
lower current limiting resistor increases the
current charge onto the test point.
30A
15A
0A
t=0nS
t
t=30nS
Figure 22. ESD Test Waveform for IEC1000-4-2
Device Pin
Tested
Driver Ouputs
Receiver Inputs
Date: 8/22/05
Date: 8/30/05
Human Body
Model
±15kV
±15kV
Air Discharge
±15kV
±15kV
IEC1000-4-2
Direct Contact
±8kV
±8kV
Level
4
4
SP3220E/EB/EU High ESD RS-232 Driver/Receiver
15
SP3220E/EB/EU High ESD RS-232 Driver/Receiver
15
© Copyright 2005 Sipex Corporation
© Copyright 2005 Sipex Corporation