Datasheet

High-input impedance is guaranteed from -13.0V to
+13.0V, when the receiver is in high-input-impedance
mode. The receiver is able to withstand the RS-232
maximum input voltage of ±25V.
Shutdown Mode
Supply current falls to less than 10µA when the
MAX3322E/MAX3323E are placed in shutdown mode
(logic low). When in shutdown mode, the devices’
charge pumps are turned off, V+ decays to V
CC
, V- is
pulled to ground, the transmitter outputs and the
receiver outputs are disabled (high impedance), and
the receiver inputs are in high impedance (Table 1).
The device enters shutdown when V
L
or V
CC
is absent.
The time required to exit shutdown is typically 50µs, as
shown in Figure 4. Connect SHDN to V
CC
if shutdown
mode is not used.
V
L
Logic Supply Input
Unlike other RS-232 interface devices, in which the
receiver outputs swing between 0 and V
CC
, the
MAX3322E/MAX3323E feature a separate logic supply
input (V
L
) that sets V
OUT
for the receiver outputs and
sets thresholds for the transmit and shutdown inputs.
This feature allows a great deal of flexibility in interfac-
ing to many types of systems with different logic levels.
Connect this input to the host logic supply (1.65V ≤ V
L
≤ 5.5V).
±15kV ESD Protection
To protect the MAX3322E/MAX3323E against ESD,
transmitters and receivers have extra protection against
static electricity to protect the device up to ±15kV. The
ESD structures withstand high ESD in all states: normal
operation, shutdown, and powered down. ESD protec-
tion can be tested in various ways; the transmitter and
receiver pins are characterized for protection to the fol-
lowing limits:
• ±15kV using the Human Body Model
• ±8kV using the IEC 1000-4-2 Contact Discharge
method
• ±15kV using the IEC 1000-4-2 Air-Gap method
Note: ESD performance depends on many conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
Human Body Model
Figure 5 shows the Human Body Model, and Figure 6
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.
MAX3322E/MAX3323E
±15kV ESD-Protected, RS-232 Transceivers for
Multidrop Applications
_______________________________________________________________________________________ 7
TXENABLE RENABLE SHDN TRANSMITTER OUTPUT
RECEIVER OUTPUT
RECEIVER INPUT
1 1 0 High-Z High-Z High-Z
1 1 1 Active Enabled 5kΩ
1 0 0 High-Z High-Z High-Z
1 0 1 Active Enabled High-Z
0 1 0 High-Z High-Z High-Z
0 1 1 High-Z Enabled 5kΩ
0 0 0 High-Z High-Z High-Z
0 0 1 High-Z Enabled High-Z
Table 1. Tx/Rx Logic
50µs/div
T2
T1
5V/div
2V/div
V
CC
= 3.3V
C1–C4 = 0.1µF
Figure 4. Transmitter Outputs when Exiting Shutdown