+2.35V to +5.5V, 1µA, 2Tx/2Rx RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins
MAX3380E/MAX3381E
R
C
1MΩ
CHARGE-CURRENT
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
R
D
1500Ω
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
HIGH-
VOLTAGE
DC
SOURCE
R
C
50MΩ to 100MΩ
CHARGE-CURRENT
LIMIT RESISTOR
R
D
330Ω
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
Cs
100pF
STORAGE
CAPACITOR
Cs
150pF
STORAGE
CAPACITOR
Figure 5a. Human Body ESD Test Model
Figure 6a. IEC 1000-4-2 ESD Test Model
I
100%
90%
I
PEAK
I
P
100%
90%
AMPERES
36.8%
10%
0
0
t
RL
TIME
Ir
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
10%
tr = 0.7ns to 1ns
30ns
60ns
t
t
DL
CURRENT WAVEFORM
Figure 5b. Human Body Current Waveform
Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform
the host logic supply (+1.65V to +5.5V). The V
L
input
will draw a maximum current of 20µA with receiver out-
puts unloaded.
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
±15kV ESD Protection
Maxim has developed state-of-the-art structures to pro-
tect these pins against an ESD of ±15kV without dam-
age. The ESD structures withstand high ESD in all states:
normal operation, shutdown, and power-down. After an
ESD event, Maxim’s “E” version devices keep working
without latch-up, whereas competing RS-232 products
can latch and must be powered down to remove latch-
up. ESD protection can be tested in various ways. The
transmitter and receiver outputs and receiver and logic
inputs of this product family are characterized for protec-
tion to the following limits:
• ±15kV using the Human Body Model
• ±8kV using the Contact Discharge method speci-
fied in IEC 1000-4-2
• ±15kV using IEC 1000-4-2’s Air-Gap Discharge
method
Human Body Model
Figure 5a shows the Human Body Model, and Figure
5b 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 test device
through a 1.5kΩ resistor.
IEC 1000-4-2
The IEC 1000-4-2 standard covers ESD testing and
performance of finished equipment; it does not specifi-
cally refer to ICs. The MAX3380E/MAX3381E help you
design equipment that meets Level 4, the highest level
of IEC 1000-4-2 without the need for additional ESD-
protection components. The major difference between
tests done using the Human Body Model and IEC
1000-4-2 is higher peak current in IEC 1000-4-2,
because series resistance is lower in the IEC 1000-4-2
model. Hence, the ESD withstand voltages measured
10
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
