The MAX13080E–MAX13089E +5.0V, ±15kV ESD-protected, RS-485/RS-422 transceivers feature one driver and
one receiver. These devices include fail-safe circuitry,
guaranteeing a logic-high receiver output when receiver
inputs are open or shorted. The receiver outputs a logichigh if all transmitters on a terminated bus are disabled
(high impedance). The MAX13080E family include a hotswap capability to eliminate false transitions on the bus
during power-up or hot insertion.
The MAX13080E/MAX13081E/MAX13082E feature
reduced slew-rate drivers that minimize EMI and
reduce reflections caused by improperly terminated
cables, allowing error-free data transmission up to
250kbps. The MAX13083E/MAX13084E also feature
slew-rate-limited drivers but allow transmit speeds up to
500kbps. The MAX13086E/MAX13087E/ MAX13088E
driver slew rates are not limited, making transmit
speeds up to 16Mbps possible. The MAX13089E slew
rate is pin selectable for 250kbps, 500kbps, and
16Mbps.
The MAX13082E/MAX13088E are intended for halfduplex communications, and the MAX13080E/
MAX13081E/MAX13083E/MAX13084E/MAX13086E/
MAX13087E are intended for full-duplex communications. The MAX13089E is selectable for half-duplex or
full-duplex operation. It also features independently
programmable receiver and transmitter output phase
through separate pins.
The MAX13080E family transceivers draw 1.2mA of
supply current when unloaded or when fully loaded with
the drivers disabled. All devices have a 1/8-unit load
receiver input impedance, allowing up to 256 transceivers on the bus.
The MAX13080E/MAX13083E/MAX13086E/MAX13089E
are available in 14-pin PDIP and 14-pin SO packages. The
MAX13081E/MAX13082E/MAX13084E/MAX13087E/
MAX13088E are available in 8-pin PDIP and 8-pin SO
packages. The devices operate over the commercial,
extended, and automotive temperature ranges.
Applications
Utility Meters
Lighting Systems
Industrial Control
Telecom
Security Systems
Instrumentation
Profibus
Features
o +5.0V Operation
o Extended ESD Protection for RS-485/RS-422 I/O Pins
±15kV Human Body Model
o True Fail-Safe Receiver While Maintaining
EIA/TIA-485 Compatibility
o Hot-Swap Input Structures on DE and RE
o Enhanced Slew-Rate Limiting Facilitates Error-
Free Data Transmission
(MAX13080E–MAX13084E/MAX13089E)
, unless otherwise noted. Typical values are at VCC= +5.0V and TA= +25°C.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
(All Voltages Referenced to GND)
Supply Voltage (V
————10ZInverting Driver Output and Inverting Receiver Input*
117—11—BInverting Receiver Input
————11BReceiver Input Resistors*
——7——BInverting Receiver Input and Inverting Driver Output
No Connect. Not internally connected, can be connected
to GND.
Half-/Full-Duplex Select Input. Connect H/F to V
half-duplex mode; connect H/F to GND or leave
unconnected for full-duplex mode.
Receiver Output. When RE is low and if (A - B) ≥ -50mV,
RO is high; if (A - B) ≤ -200mV, RO is low.
Receiver Output Enable. Drive RE low to enable RO; RO is
high impedance when RE is high. Drive RE high and DE
low to enter low-power shutdown mode. RE is a hot-swap
input (see the Hot-Swap Capability section for details).
Driver Output Enable. Drive DE high to enable driver
outputs. These outputs are high impedance when DE is
low. Drive RE high and DE low to enter low-power
shutdown mode. DE is a hot-swap input (see the Hot-Swap Capability section for details).
D r i ver Inp ut. W i th D E hi g h, a l ow on D I for ces noni nver ti ng
outp ut l ow and i nver ti ng outp ut hi g h. S i m i l ar l y, a hi g h on D I
for ces noni nver ti ng outp ut hi g h and i nver ti ng outp ut l ow .
Slew-Rate Limit Selector Input. Connect SRL to ground for
16Mbps communication rate; connect SRL to V
500kbps communication rate. Leave SRL unconnected for
250kbps communication rate.
Tr ansm i tter P hase. C onnect TX P to g r ound or l eave TX P
unconnected for nor m al tr ansm i tter p hase/p ol ar i ty. C onnect
TX P to V
Noninverting Driver Output and Noninverting Receiver
Input*
to i nver t the tr ansm i tter p hase/p ol ar i ty.
X = Don’t care; shutdown mode, driver, and receiver outputs are high impedance.
TRANSMITTING
INPUTSOUTPUTS
REDEDIB/ZA/Y
X1101
X1010
00XHigh-ZHigh-Z
10XShutdown
INPUTSOUTPUTS
TXPREDEDIZY
0X1101
0X1010
1X1110
1X1001
X00XHigh-ZHigh-Z
X10XShutdown
TRANSMITTING
RECEIVING
INPUTSOUTPUTS
REDEA-BRO
0X≥ -50mV1
0X≤ -200mV0
0X
11XHigh-Z
10XShutdown
Open/
shorted
1
RECEIVING
INPUTSOUTPUTS
H/FRXPREDEA, BY, ZRO
000X> -50mVX1
000X< -200mVX0
010X> -50mVX0
010X< -200mVX1
1000X> -50mV1
1000X< -200mV0
1100X> -50mV0
1100X< -200mV1
000XOpen/shortedX1
1000XOpen/shorted1
010XOpen/shortedX0
1100XOpen/shorted0
XX11XXHigh-Z
XX10XXShutdown
Detailed Description
The MAX13080E–MAX13089E high-speed transceivers
for RS-485/RS-422 communication contain one driver
and one receiver. These devices feature fail-safe circuitry, which guarantees a logic-high receiver output when
the receiver inputs are open or shorted, or when they
are connected to a terminated transmission line with all
drivers disabled (see the
Fail-Safe
section). The
MAX13080E/MAX13082E/MAX13083E/MAX13086E/
MAX13088E/MAX13089E also feature a hot-swap capability allowing line insertion without erroneous data transfer (see the
Hot Swap Capability
section). The
MAX13080E/MAX13081E/MAX13082E feature reduced
slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing
error-free data transmission up to 250kbps. The
MAX13083E/MAX13084E also offer slew-rate limits
allowing transmit speeds up to 500kbps. The
MAX13086E/MAX13087E/MAX13088Es’ driver slew
rates are not limited, making transmit speeds up to
16Mbps possible. The MAX13089E’s slew rate is selectable between 250kbps, 500kbps, and 16Mbps by driving a selector pin with a three-state driver.
The MAX13082E/MAX13088E are half-duplex transceivers,
while the MAX13080E/MAX13081E/ MAX13083E/
MAX13084E/MAX13086E/MAX13087E are full-duplex
transceivers. The MAX13089E is selectable between
half- and full-duplex communication by driving a selector pin (H/F) high or low, respectively.
All devices operate from a single +5.0V supply. Drivers
are output short-circuit current limited. Thermal-shutdown
circuitry protects drivers against excessive power dissipation. When activated, the thermal-shutdown circuitry
places the driver outputs into a high-impedance state.
Receiver Input Filtering
The receivers of the MAX13080E–MAX13084E, and the
MAX13089E when operating in 250kbps or 500kbps
mode, incorporate input filtering in addition to input
hysteresis. This filtering enhances noise immunity with
differential signals that have very slow rise and fall
times. Receiver propagation delay increases by 25%
due to this filtering.
Fail-Safe
The MAX13080E family guarantees a logic-high receiver
output when the receiver inputs are shorted or open, or
when they are connected to a terminated transmission
line with all drivers disabled. This is done by setting the
receiver input threshold between -50mV and -200mV. If
the differential receiver input voltage (A - B) is greater
than or equal to -50mV, RO is logic-high. If (A - B) is less
than or equal to -200mV, RO is logic-low. In the case of a
terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled to 0V by the termination. With the receiver thresholds of the MAX13080E
family, this results in a logic-high with a 50mV minimum
noise margin. Unlike previous fail-safe devices, the
-50mV to -200mV threshold complies with the ±200mV
EIA/TIA-485 standard.
Hot-Swap Capability (Except
MAX13081E/MAX13084E/MAX13087E)
Hot-Swap Inputs
When circuit boards are inserted into a hot or powered
backplane, differential disturbances to the data bus
can lead to data errors. Upon initial circuit board insertion, the data communication processor undergoes its
own power-up sequence. During this period, the
processor’s logic-output drivers are high impedance
and are unable to drive the DE and RE inputs of these
devices to a defined logic level. Leakage currents up to
±10µA from the high-impedance state of the processor’s logic drivers could cause standard CMOS enable
inputs of a transceiver to drift to an incorrect logic level.
Additionally, parasitic circuit board capacitance could
cause coupling of VCCor GND to the enable inputs.
Without the hot-swap capability, these factors could
improperly enable the transceiver’s driver or receiver.
When VCCrises, an internal pulldown circuit holds DE
low and RE high. After the initial power-up sequence,
the pulldown circuit becomes transparent, resetting the
hot-swap tolerable input.
Hot-Swap Input Circuitry
The enable inputs feature hot-swap capability. At the
input there are two NMOS devices, M1 and M2
(Figure 9). When VCCramps from zero, an internal 7µs
timer turns on M2 and sets the SR latch, which also
turns on M1. Transistors M2, a 500µA current sink, and
M1, a 100µA current sink, pull DE to GND through a
5kΩ resistor. M2 is designed to pull DE to the disabled
state against an external parasitic capacitance up to
100pF that can drive DE high. After 7µs, the timer
deactivates M2 while M1 remains on, holding DE low
against three-state leakages that can drive DE high. M1
remains on until an external source overcomes the
required input current. At this time, the SR latch resets
and M1 turns off. When M1 turns off, DE reverts to a
standard, high-impedance CMOS input. Whenever V
CC
drops below 1V, the hot-swap input is reset.
For RE there is a complementary circuit employing two
The MAX13089E has several programmable operating
modes. Transmitter rise and fall times are programmable, resulting in maximum data rates of 250kbps,
500kbps, and 16Mbps. To select the desired data rate,
drive SRL to one of three possible states by using a
three-state driver: VCC, GND, or unconnected. For
250kbps operation, set the three-state device in highimpedance mode or leave SRL unconnected. For
500kbps operation, drive SRL high or connect it to VCC.
For 16Mbps operation, drive SRL low or connect it to
GND. SRL can be changed during operation without
interrupting data communications.
Occasionally, twisted-pair lines are connected backward
from normal orientation. The MAX13089E has two pins
that invert the phase of the driver and the receiver to correct this problem. For normal operation, drive TXP and
RXP low, connect them to ground, or leave them unconnected (internal pulldown). To invert the driver phase,
drive TXP high or connect it to VCC. To invert the receiver
phase, drive RXP high or connect it to VCC. Note that the
receiver threshold is positive when RXP is high.
The MAX13089E can operate in full- or half-duplex
mode. Drive H/F low, leave it unconnected (internal
pulldown), or connect it to GND for full-duplex opera-
tion. Drive H/F high for half-duplex operation. In fullduplex mode, the pin configuration of the driver and
receiver is the same as that of a MAX13080E. In halfduplex mode, the receiver inputs are internally connected to the driver outputs through a resistor-divider. This
effectively changes the function of the device’s outputs.
Y becomes the noninverting driver output and receiver
input, Z becomes the inverting driver output and receiver
input. In half-duplex mode, A and B are still connected to
ground through an internal resistor-divider but they are
not internally connected to the receiver.
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electrostatic discharges encountered during handling and
assembly. The driver outputs and receiver inputs of the
MAX13080E family of devices have extra protection
against static electricity. Maxim’s engineers have 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, the
MAX13080E family keep working without latchup or
damage.
ESD protection can be tested in various ways. The
transmitter outputs and receiver inputs of the
MAX13080E family are characterized for protection to
the following limits:
• ±15kV using the Human Body Model
• ±6kV using the Contact Discharge method specified
in IEC 61000-4-2
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 10a shows the Human Body Model, and Figure
10b shows the current waveform it generates when discharged 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 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. However, it does
not specifically refer to integrated circuits. The
MAX13080E family of devices helps you design equipment to meet IEC 61000-4-2, without the need for additional ESD-protection components.
Figure 9. Simplified Structure of the Driver Enable Pin (DE)
V
CC
10μs
TIMER
SR LATCH
TIMER
DE
5kΩ
100μA
500μA
M2M1
DE
(HOT SWAP)
The major difference between tests done using the
Human Body Model and IEC 61000-4-2 is higher peak
current in IEC 61000-4-2 because series resistance is
lower in the IEC 61000-4-2 model. Hence, the ESD withstand voltage measured to IEC 61000-4-2 is generally
lower than that measured using the Human Body Model.
Figure 10c shows the IEC 61000-4-2 model, and Figure
10d shows the current waveform for IEC 61000-4-2 ESD
Contact Discharge test.
Machine Model
The machine model for ESD tests all pins using a
200pF storage capacitor and zero discharge resistance. The objective is to emulate the stress caused
when I/O pins are contacted by handling equipment
during test and assembly. Of course, all pins require
this protection, not just RS-485 inputs and outputs.
Applications Information
256 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12kΩ
(1-unit load), and the standard driver can drive up to 32unit loads. The MAX13080E family of transceivers has a
1/8-unit load receiver input impedance (96kΩ), allowing
up to 256 transceivers to be connected in parallel on one
communication line. Any combination of these devices,
as well as other RS-485 transceivers with a total of 32unit loads or fewer, can be connected to the line.
Reduced EMI and Reflections
The MAX13080E/MAX13081E/MAX13082E feature
reduced slew-rate drivers that minimize EMI and
reduce reflections caused by improperly terminated
cables, allowing error-free data transmission up to
250kbps. The MAX13083E/MAX13084E offer higher driver output slew-rate limits, allowing transmit speeds up
to 500kbps. The MAX13089E with SRL = VCCor unconnected are slew-rate limited. With SRL unconnected,
the MAX13089E error-free data transmission is up to
250kbps. With SRL connected to VCC, the data transmit
speeds up to 500kbps.
Figure 10d. IEC 61000-4-2 ESD Generator Current Waveform
HIGH-
VOLTAGE
DC
SOURCE
R
C
1MΩ
CHARGE-CURRENT-
LIMIT RESISTOR
C
s
100pF
R
D
1500Ω
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
AMPS
IP 100%
90%
36.8%
10%
0
0
t
RL
I
r
TIME
t
DL
CURRENT WAVEFORM
DEVICE
UNDER
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
TEST
HIGH-
VOLTAGE
DC
SOURCE
R
C
50MΩ TO 100MΩ
CHARGE-CURRENT-
LIMIT RESISTOR
C
150pF
s
R
D
330Ω
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
I
100%
90%
PEAK
I
10%
tr = 0.7ns TO 1ns
30ns
60ns
DEVICE
UNDER
TEST
t
MAX13080E–MAX13084E/MAX13086E–MAX13089E
Low-Power Shutdown Mode (Except
MAX13081E/MAX13084E/MAX13087E)
Low-power shutdown mode is initiated by bringing both
RE high and DE low. In shutdown, the devices typically
draw only 2.8µA of supply current.
RE and DE can be driven simultaneously; the devices
are guaranteed not to enter shutdown if RE is high and
DE is low for less than 50ns. If the inputs are in this
state for at least 700ns, the devices are guaranteed to
enter shutdown.
Enable times t
ZH
and tZL(see the
Switching
Characteristics
section) assume the devices were not in
a low-power shutdown state. Enable times t
ZH(SHDN)
and
t
ZL(SHDN)
assume the devices were in shutdown state. It
takes drivers and receivers longer to become enabled
from low-power shutdown mode (t
ZH(SHDN)
, t
ZL(SHDN)
)
than from driver/receiver-disable mode (tZH, tZL).
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or by bus contention.
The first, a foldback current limit on the output stage,
provides immediate protection against short circuits over
the whole common-mode voltage range (see the
Typical
Operating Characteristics
). The second, a thermal-shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature exceeds +175°C (typ).
Line Length
The RS-485/RS-422 standard covers line lengths up to
4000ft. For line lengths greater than 4000ft, use the
repeater application shown in Figure 11.
Typical Applications
The MAX13082E/MAX13088E/MAX13089E transceivers
are designed for bidirectional data communications on
multipoint bus transmission lines. Figures 12 and 13
show typical network applications circuits.
To minimize reflections, terminate the line at both ends
in its characteristic impedance, and keep stub lengths
off the main line as short as possible. The slew-rate-limited MAX13082E and the two modes of the MAX13089E
are more tolerant of imperfect termination.
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________