±15kV ESD-Protected, Slew-Rate-Limited,
Low-Power, RS-485/RS-422 Transceivers
__________Function Tables
(MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E)
Table 1. Transmitting
INPUTS
RE
X
X
0
1
DE
1
1
0
0
DI
1
0
X
X
Z
0
1
High-Z
High-Z
*
OUTPUTS
Y
1
0
High-Z
High-Z
*
RE
0
0
0
1
MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E
Table 2. Receiving
INPUTS
DE
0
0
0
0
A-B
> +0.2V
< -0.2V
Inputs open
X
OUTPUT
RO
1
0
1
High-Z
*
X = Don't care
High-Z = High impedance
*
Shutdown mode for MAX481E/MAX483E/MAX487E
X = Don't care
High-Z = High impedance
*
Shutdown mode for MAX481E/MAX483E/MAX487E
__________Applications Information
The MAX481E/MAX483E/MAX485E/MAX487E–MAX491E
and MAX1487E are low-power transceivers for RS-485
and RS-422 communications. These “E” versions of the
MAX481, MAX483, MAX485, MAX487–MAX491, and
MAX1487 provide extra protection against ESD. The
rugged MAX481E, MAX483E, MAX485E, MAX497E–
MAX491E, and MAX1487E are intended for harsh envi-
ronments where high-speed communication is important.
These devices eliminate the need for transient suppres-
sor diodes and the associated high capacitance loading.
The standard (non-“E”) MAX481, MAX483, MAX485,
MAX487–MAX491, and MAX1487 are recommended for
applications where cost is critical.
The MAX481E, MAX485E, MAX490E, MAX491E, and
MAX1487E can transmit and receive at data rates up to
2.5Mbps, while the MAX483E, MAX487E, MAX488E,
and MAX489E are specified for data rates up to
250kbps. The MAX488E–MAX491E are full-duplex
transceivers, while the MAX481E, MAX483E, MAX487E,
and MAX1487E are half-duplex. In addition, driver-
enable (DE) and receiver-enable (RE) pins are included
on the MAX481E, MAX483E, MAX485E, MAX487E,
MAX489E, MAX491E, and MAX1487E. When disabled,
the driver and receiver outputs are high impedance.
neers developed state-of-the-art structures to protect
these pins against ESD of ±15kV without damage. The
ESD structures withstand high ESD in all states: normal
operation, shutdown, and powered down. After an ESD
event, Maxim’s MAX481E, MAX483E, MAX485E,
MAX487E–MAX491E, and MAX1487E keep working
without latchup.
ESD protection can be tested in various ways; the
transmitter outputs and receiver inputs of this product
family are characterized for protection to ±15kV using
the Human Body Model.
Other ESD test methodologies include IEC10004-2 con-
tact discharge and IEC1000-4-2 air-gap discharge (for-
merly IEC801-2).
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test set-up, test methodology, and test results.
Human Body Model
Figure 4 shows the Human Body Model, and Figure 5
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.
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 (Figure 6).
9
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro-
static discharges encountered during handling and
assembly. The driver outputs and receiver inputs have
extra protection against static electricity. Maxim’s engi-
_______________________________________________________________________________________
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
