Datasheet

±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V,
Up to 1Mbps, True RS-232 Transceivers
For the MAX3237E, all logic and RS-232 I/O pins are
characterized for protection to ±15kV per the Human
Body Model.
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
Human Body Model
Figure 4a shows the Human Body Model, and Figure
4b 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 interest,
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 integrated circuits. The MAX3222E/
MAX3232E/MAX3237E/MAX3241E/MAX3246E 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 with-
stand voltage measured to IEC 1000-4-2 is generally
lower than that measured using the Human Body
Model. Figure 5a shows the IEC 1000-4-2 model, and
Figure 5b shows the current waveform for the ±8kV IEC
1000-4-2 level 4 ESD Contact Discharge test. The Air-
Gap Discharge test involves approaching the device
with a charged probe. The Contact Discharge method
connects the probe to the device before the probe is
energized.
Machine Model
The Machine Model for ESD tests all pins using a
200pF storage capacitor and zero discharge resis-
tance. Its objective is to emulate the stress caused by
contact that occurs with handling and assembly during
manufacturing. All pins require this protection during
manufacturing, not just RS-232 inputs and outputs.
Therefore, after PC board assembly, the Machine
Model is less relevant to I/O ports.
Table 2. Required Minimum Capacitor
Values
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
012345678910
MAX3222E-fig06a
LOAD CURRENT PER TRANSMITTER (mA)
TRANSMITTER OUTPUT VOLTAGE (V)
V
OUT+
V
OUT-
V
OUT+
V
OUT-
V
CC
V
CC
= 3.0V
Figure 6a. MAX3241E Transmitter Output Voltage vs. Load
Current Per Transmitter
Table 3. Logic-Family Compatibility with
Various Supply Voltages
V
CC
(V)
C1
(µF)
C2, C3, C4
(µF)
MAX3222E/MAX3232E/MAX3241E
3.0 to 3.6 0.1 0.1
4.5 to 5.5 0.047 0.33
3.0 to 5.5 0.1 0.47
MAX3237E/MAX3246E
3.0 to 3.6 0.22 0.22
3.15 to 3.6 0.1 0.1
4.5 to 5.5 0.047 0.33
3.0 to 5.5 0.22 1.0
SYSTEM
POWER-SUPPLY
VOLTAGE
(V)
V
CC
SUPPLY
VOLTAGE
(V)
COMPATIBILITY
3.3 3.3
Compatible with all
CMOS families
55
Compatible with all
TTL and CMOS
families
5 3.3
C om p ati b l e w i th AC T
and H C T C M OS , and
w i th AC , H C , or
C D 4000 C M O S
12
Maxim Integrated
MAX3222E/MAX3232E/MAX3237E/
MAX3241E/MAX3246E