MAX1406 Datasheet, PDF (6/8 Pages) Maxim Integrated Products – ±15kV ESD-Protected, EMC-Compliant, 230kbps, 3-Tx/3-Rx RS-232 IC

±15kV ESD-Protected, EMC-Compliant,
230kbps, 3-Tx/3-Rx RS-232 IC
Human Body Model
Figure 2a shows the Human Body Model, and Figure
2b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter-
est, which is then discharged into the device through a
1.5kΩ resistor.
IEC1000-4-2
The IEC1000-4-2 standard covers ESD testing and per-
formance of finished equipment; it does not specifically
refer to integrated circuits. The MAX1406 helps you
design equipment that meets Level 4 (the highest level)
of IEC1000-4-2, without additional ESD-protection com-
ponents.
The main difference between tests done using the
Human Body Model and IEC1000-4-2 is higher peak
current in IEC1000-4-2 (Figure 3). Because series resis-
tance is lower in the IEC1000-4-2 ESD test model, the
ESD withstand voltage measured to this standard is
generally lower than that measured using the Human
Body Model. Figure 3b shows the current waveform for
the ±8kV IEC1000-4-2 Level 4 ESD Contact-Discharge
test.
The Air-Gap test involves approaching the device with
a charge probe. The Contact-Discharge method con-
nects the probe to the device before the probe is ener-
gized.
Machine Model
The Machine Model for ESD testing uses a 200pF stor-
age capacitor and zero-discharge resistance. It mimics
the stress caused by handling during manufacturing
and assembly. Of course, all pins (not just RS-232
inputs and outputs) require this protection during man-
ufacturing. Therefore, the Machine Model is less rele-
vant to the I/O ports than are the Human Body Model
and IEC1000-4-2.
R_C 1M
CHARGE-CURRENT
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
Cs
100pF
R_D 1500Ω
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
R_C 50M to 100M
R_D 330Ω
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
HIGH-
VOLTAGE
DC
SOURCE
Cs
150pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
a)
I_P 100%
90%
AMPERES
36.8%
10%
0
0 _tRL
b)
Ir
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
TIME
t_DL
CURRENT WAVEFORM
Figure 2. Human Body ESD Test Model and ESD-Generator
Current Waveform
a)
I
100%
90%
10%
tr = 0.7ns to 1ns
30ns
t
60ns
b)
Figure 3. IEC1000-4-2 Test Model and ESD-Generator Current
Waveform
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