SP3249E Datasheet, PDF (11/14 Pages) Sipex Corporation – Intelligent +3.0V to +5.5V RS-232 Transceivers

R_CC
DC Power
Source
SW1
Contact-Discharge Module
R_SS
R_V
SW2
C_SS
Device
Under
Test
Figure 17. ESD Test Circuit for IEC1000-4-2
The circuit model in Figures 16 and 17 represent
the typical ESD testing circuit 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.
For the Human Body Model, the current limiting
resistor (R_S) and the source capacitor (C_S) are
1.5kW an 100pF, respectively. For IEC-1000-4-
2, the current limiting resistor (R_S) and the source
capacitor (C_S) are 330W an 150pF, respectively.
The higher C_S value and lower R_S 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.
RS and RV add up to 330Ω for IEC1000-4-2.
30A
15A
0A
t=0ns
t=30ns
t➙
Figure 18. ESD Test Waveform for IEC1000-4-2
DEVICE PIN
TESTED
HUMAN BODY
IEC1000-4-2
MODEL
Air Discharge Direct Contact
Driver Outputs
Receiver Inputs
±15kV
±15kV
±15kV
±15kV
±8kV
±8kV
Table 2. Transceiver ESD Tolerance Levels
Level
4
4
Rev.4/08/02
SP3249E Intelligent +3.0V to +5.5V RS-232 Transceivers
11
© Copyright 2002 Sipex Corporation