General Description
The MAX13442E/MAX13444E are fault-protected RS-485
and J1708 transceivers that feature ±80V protection
from signal faults on communication bus lines. The
MAX13442E/MAX13444E feature a reduced slew-rate
driver that minimizes EMI and reflections, allowing error-
free transmission up to 250kbps. The MAX13443E driver
can transmit up to 10Mbps. The high-speed MAX13443E
RS-485 transceiver features ±60V protection from signal
faults on communication bus lines. These transceivers
feature foldback current limit. Each device contains one
differential line driver with three-state output and one dif-
ferential line receiver with three-state input. The 1/4-unit-
load receiver input impedance allows up to 128 transceiv-
ers on a single bus. The devices operate from a 5V sup-
ply. True fail-safe inputs guarantee a logic-high receiver
output when the receiver inputs are open, shorted, or
connected to an idle data line.
Hot-swap circuitry eliminates false transitions on the data
bus during circuit initialization or connection to a live back-
plane. Short-circuit current-limiting and thermal-shutdown
circuitry protect the driver against excessive power dis-
sipation, and on-chip ±15kV ESD protection eliminates
costly external protection devices.
The MAX13442E/MAX13443E/MAX13444E are available
in an 8-pin SO package and are specified over the auto-
motive temperature range.
Features
●±15kV ESD Protection
●±80V Fault Protection (±60V MAX13443E)
●Guaranteed 10Mbps Data Rate (MAX13443E)
●Hot-Swappable for Telecom Applications
●True Fail-Safe Receiver Inputs
●Enhanced Slew-Rate-Limiting Facilitates Error-Free
Data Transmission (MAX13442E/MAX13444E)
●Allow Up to 128 Transceivers on the Bus
●-7V to +12V Common-Mode Input Range
●±6mA FoldBack Current Limit
●Industry-Standard Pinout
Applications
19-3898; Rev 3; 3/11
●RS-422/RS-485
Communications
●Truck and Trailer
Applications
●Industrial Networks
●Telecommunications
Systems
●Automotive Applications
●HVAC Controls
Pin Configurations and Typical Operating Circuits continued at end of data sheet.
+Denotes lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
T = Tape and reel.
PART TEMP RANGE PIN-PACKAGE
MAX13442EASA+ -40°C to +125°C 8 SO
MAX13443EASA+ -40°C to +125°C 8 SO
MAX13444EASA/V+T -40°C to +125°C 8 SO
PART TYPE DATA RATE
(Mbps)
FAULT
PROTECTION (V)
LOW-POWER
SHUTDOWN
RECEIVER/DRIVER
ENABLE
TRANSCEIVERS
ON BUS HOT SWAP
MAX13442E RS-485 0.25 ±80 Yes Ye s 128 Yes
MAX13443E RS-485 10 ±60 Yes Ye s 128 Yes
MAX13444E J1708 0.25 ±80 Yes Yes 128 Yes (only RE)
TOP VIEW
1
2
3
4
8
5
VCC
GND
DI
DE
RE
RO R
D
RT
RT
7
6
D
R
DE
RE
DI
RO
A
B
1
2
3
4
8
7
6
5
VCC
B
A
GND
DI
DE
RE
RO
SO SO
R
D
B
A
MAX13442E
MAX13443E
++
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Pin Congurations and Typical Operating Circuits
Ordering Information
Selector Guide
(Voltages referenced to GND.)
VCC ........................................................................................+7V
RE, DE, DE, DI, TXD ............................... -0.3V to (VCC + 0.3V)
A, B (Note 1) (MAX13442E/MAX13444E)...........................±80V
A, B (Note 1) (MAX13443E) ................................................ ±60V
RO ............................................................ -0.3V to (VCC + 0.3V)
Short-Circuit Duration (RO, A, B) ..............................Continuous
Continuous Power Dissipation (TA = +70°C)
SO (derate 7.6mW/°C above +70°C) ..........................606mW
Operating Temperature Range ......................... -40°C to +125°C
Storage Temperature Range ............................ -65°C to +150°C
Junction Temperature ...................................................... +150°C
Lead Temperature (soldering, 10s) ................................. +300°C
Soldering Temperature (reflow) .......................................+260°C
SO
Junction-to-Ambient Thermal Resistance (θJA) ........132°C/W Junction-to-Case Thermal Resistance (θJC) ...............38°C/W
(Note 2)
(VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DRIVER
Differential Driver Output VOD
Figure 1, RL = 100Ω 2 VCC V
Figure 1, RL = 54Ω 1.5 VCC
Change in Magnitude of
Differential Output Voltage ΔVOD Figure 1, RL = 100Ω or 54Ω (Note 3) 0.2 V
Driver Common-Mode
Output Voltage VOC Figure 1, RL = 100Ω or 54Ω VCC/2 3 V
Change in Magnitude of
Common-Mode Voltage DVOC
Figure 1, RL = 100Ω or 54Ω (Note 3)
(MAX13442E/MAX13443E) 0.2 V
DRIVER LOGIC
Driver-Input High Voltage VDIH 2 V
Driver-Input Low Voltage VDIL 0.8 V
Driver-Input Current IDIN ±2 µA
Driver Short-Circuit Output
Current (Note 4) IOSD
0V ≤ VOUT ≤ +12V +350 mA
-7V ≤ VOUT ≤ VCC -350
Driver Short-Circuit Foldback
Output Current IOSDF
(VCC - 1V) ≤ VOUT ≤ +12V (Note 4) +25 mA
-7V ≤ VOUT ≤ +1V (Note 4) -25
Driver-Limit Short-Circuit
Foldback Output Current IOSDL
VOUT ≥ +20V, RL = 100Ω +6 mA
VOUT ≤ -15V, RL = 100Ω -6
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
www.maximintegrated.com Maxim Integrated
│
2
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Note 1: During normal operation, a termination resistor must be connected between A and B in order to guarantee overvoltage protec-
tion up to the absolute maximum rating of this device. When not in operation, these devices can withstand fault voltages up
to the maximum rating without a termination resistor and will not be damaged.
Absolute Maximum Ratings
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.
Package Thermal Characteristics
DC Electrical Characteristics
(VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RECEIVER
Input Current IA,B
A, B
receive
mode
VCC = GND, VA, B = 12V 250 µA
VA, B = -7V -150
VA, B = ±80V ±6 mA
Receiver-Differential Threshold
Voltage VTH -7V ≤ VCM ≤ +12V -200 -50 mV
Receiver-Input Hysteresis ΔVTH 25 mV
RECEIVER LOGIC
Output-High Voltage VOH Figure 2, IOH = -1.6mA VCC - 0.6 V
Output-Low Voltage VOL Figure 2, IOL = 1mA 0.4 V
Three-State Output Current at
Receiver IOZR 0V ≤ VA, B ≤ VCC ±1 µA
Receiver Input Resistance RIN -7V ≤ VCM ≤ +12V 48 kΩ
Receiver Output Short-Circuit
Current IOSR 0V ≤ VRO ≤ VCC ±95 mA
CONTROL
Control-Input High Voltage VCIH DE, DE, RE 2 V
Input-Current Latch During First
Rising Edge IIN DE, RE 90 µA
SUPPLY CURRENT
Normal Operation ICC
No load,
DI = VCC
or GND
DE = VCC, RE = GND
(MAX13442E)
(DE = RE = GND)
(MAX13444E)
30
mA
(DE = VCC, RE = GND)
(MAX13443E) 10
Supply Current in Shutdown
Mode ISHDN
DE = GND, RE = VCC
(MAX13442E/MAX13443E) 20
µA
DE = GND, RE = VCC, TA = +25°C
(MAX13442E/MAX13443E) 10
DE = RE = VCC (MAX13444E) 100
DE = RE = VCC, TA = +25°C (MAX13444E) 10
Supply Current with Output
Shorted to ±60V ISHRT DE = GND, RE = GND, no load
output in three-state (MAX13443E) ±15 mA
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
www.maximintegrated.com Maxim Integrated
│
3
DC Electrical Characteristics (continued)
(VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.)
(VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Driver Propagation Delay tPLHA,
tPLHB
Figure 3, R
L
= 54Ω, C
L
= 50pF (MAX13442E) 2000 ns
R
DIFF
= 60Ω, C
DIFF
= 100pF (MAX13444E)
Driver Differential Propagation Delay tDPLH,
tDPHL
R
L
= 54Ω, C
L
= 50pF, Figure 4 2000 ns
Driver Differential Output
Transition Time tLH,tHL R
L
= 54Ω, C
L
= 50pF, Figure 4 200 2000 ns
Driver Output Skew tSKEWAB,
tSKEWBA
R
L
= 54Ω, C
L
= 50pF,
t
SKEWAB
= |t
PLHA
- t
PHLB
|,
t
SKEWBA
= |t
PLHB
- t
PHLA
|
350 ns
Differential Driver Output Skew tDSKEW
R
L
= 54Ω, C
L
= 50pF,
t
DSKEW
= |t
DPLH
- t
DPHL
|200 ns
Maximum Data Rate fMAX 250 kbps
Driver Enable Time to Output High t
PDZH
R
L
= 500Ω, C
L
= 50pF, Figure 5 2000 ns
Driver Disable Time from Output High tPDHZ R
L
= 500Ω, C
L
= 50pF, Figure 5 2000 ns
Driver Enable Time from Shutdown to
Output High tPDHS R
L
= 500Ω, C
L
= 50pF, Figure 5 4.2 µs
Driver Enable Time to Output Low tPDZL R
L
= 500Ω, C
L
= 50pF, Figure 6 2000 ns
Driver Disable Time from Output Low tPDLZ R
L
= 500Ω, C
L
= 50pF, Figure 6 2000 ns
Driver Enable Time from Shutdown to
Output Low tPDLS R
L
= 500Ω, C
L
= 50pF, Figure 6 4.2 µs
Driver Time to Shutdown tSHDN R
L
= 500Ω, C
L
= 50pF 800 ns
Receiver Propagation Delay tRPLH,
tRPHL
C
L
= 20pF, V
ID
= 2V, V
CM
= 0V, Figure 7 2000 ns
Receiver Output Skew tRSKEW C
L
= 20pF, t
RSKEW
= |t
RPLH
- t
RPHL
| 200 ns
Receiver Enable Time to Output High tRPZH R
L
= 1kΩ, C
L
= 20pF, Figure 8 2000 ns
Receiver Disable Time from Output High tRPHZ R
L
= 1kΩ, C
L
= 20pF, Figure 8 2000 ns
Receiver Wake Time from Shutdown tRPWAKE R
L
= 1kΩ, C
L
= 20pF, Figure 8 4.2 µs
Receiver Enable Time to Output Low tRPZL R
L
= 1kΩ, C
L
= 20pF, Figure 8 2000 ns
Receiver Disable Time from Output Low tRPLZ R
L
= 1kΩ, C
L
= 20pF, Figure 8 2000 ns
Receiver Time to Shutdown tSHDN R
L
= 500Ω, C
L
= 50pF 800 ns
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Overvoltage Protection A, B; RSOURCE = 0
Ω
,
RL = 54
Ω
MAX13442E/
MAX13444E ±80 V
MAX13443E ±60
ESD Protection A, B Human Body Model ±15 kV
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
www.maximintegrated.com Maxim Integrated
│
4
Protection Specications
Switching Characteristics (MAX13442E/MAX13444E)
(VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.)
Note 3: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes state.
Note 4: The short-circuit output current applies to peak current just before foldback current limiting. The short-circuit foldback output
current applies during current limiting to allow a recovery from bus contention.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Driver Propagation Delay t
PLHA
,
t
PLHB
R
L
= 27
Ω
, C
L
= 50pF, Figure 3 60 ns
Driver Differential Propagation Delay t
DPLH
,
t
DPHL
R
L
= 54
Ω
, C
L
= 50pF, Figure 4 60 ns
Driver Differential Output
Transition Time t
LH
,t
HL
R
L
= 54
Ω
, CL = 50pF, Figure 4 25 ns
Driver Output Skew tSKEWAB,
tSKEWBA
R
L
= 54
Ω
, C
L
= 50pF,
t
SKEWAB
= |t
PLHA
- t
PHLB
|,
t
SKEWBA
= |t
PLHB
- t
PHLA
|
10 ns
Differential Driver Output Skew t
DSKEW
R
L
= 54
Ω
, C
L
= 50pF,
t
DSKEW
= |t
DPLH
- t
DPHL
|10 ns
Maximum Data Rate f
MAX
10 Mbps
Driver Enable Time to Output High t
PDZH
RL = 500
Ω
, C
L
= 50pF, Figure 5 1200 ns
Driver Disable Time from Output High t
PDHZ
RL = 500
Ω
, C
L
= 50pF, Figure 5 1200 ns
Driver Enable Time from Shutdown to
Output High t
PDHS
R
L
= 500
Ω
, C
L
= 50pF, Figure 5 4.2 µs
Driver Enable Time to Output Low t
PDZL
R
L
= 500
Ω
, C
L
= 50pF, Figure 6 1200 ns
Driver Disable Time from Output Low t
PDLZ
R
L
= 500Ω, C
L
= 50pF, Figure 6 1200 ns
Driver Enable Time from Shutdown to
Output Low t
PDLS
R
L
= 500Ω, C
L
= 50pF, Figure 6 4.2 Fs
Driver Time to Shutdown t
SHDN
R
L
= 500Ω, C
L
= 50pF, Figure 6 800 ns
Receiver Propagation Delay t
RPLH
,
t
RPHL
C
L
= 20pF, V
ID
= 2V, V
CM
= 0V, Figure 7 85 ns
Receiver Output Skew t
RSKEW
C
L
= 20pF, t
RSKEW
= |t
RPLH
- t
RPHL
| 15 ns
Receiver Enable Time to Output High t
RPZH
R
L
= 1kΩ, C
L
= 20pF, Figure 8 400 ns
Receiver Disable Time from Output High t
RPHZ
R
L
= 1kΩ, C
L
= 20pF, Figure 8 400 ns
Receiver Wake Time from Shutdown tRPWAKE R
L
= 1k
Ω
, C
L
= 20pF, Figure 8 4.2 µs
Receiver Enable Wake Time from
Shutdown t
RPSH
R
L
= 1kΩ, C
L
= 20pF, Figure 8 400 ns
Receiver Disable Time from Output Low t
RPLZ
R
L
= 1kΩ, C
L
= 20pF, Figure 8 400 ns
Receiver Time to Shutdown t
SHDN
R
L
= 500Ω, C
L
= 50pF 800 ns
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
www.maximintegrated.com Maxim Integrated
│
5
Switching Characteristics (MAX13443E)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
MAX13442-4E toc02
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
1109580655035205-10-25
4
8
12
16
20
24
0
-40 125
DRIVER AND RECEIVER
ENABLED
MAX13442E/MAX13444E
DRIVER DISABLED,
RECEIVER ENABLED
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX13442-4E toc03
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (µA)
120100806040200-20
0.00001
0.0001
0.001
0.01
0.1
1
10
0.000001
-40
MAX13442E
DI = DE = GND
RE = VCC
0
10
5
15
30
35
25
20
40
0 1.0 1.5 2.0 2.50.5 3.0 3.5 4.0 4.5 5.0
RECEIVER OUTPUT CURRENT
vs. OUTPUT-LOW VOLTAGE
MAX13442-4E toc04
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT CURRENT (mA)
0
10
5
15
30
35
25
20
40
0 1.0 1.5 2.0 2.50.5 3.0 3.5 4.0 4.5 5.0
RECEIVER OUTPUT CURRENT
vs. OUTPUT-HIGH VOLTAGE
MAX13442-4E toc05
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT CURRENT (mA)
0
1.0
0.5
2.5
2.0
1.5
3.0
3.5
4.5
4.0
5.0
-40 -10 5-25 20 35 50 65 80 95 110 125
RECEIVER OUTPUT VOLTAGE
vs. TEMPERATURE
MAX13442-4E toc06
TEMPERATURE (°C)
RECEIVER OUTPUT VOLTAGE (V)
VOL, IOUT = -10mA
VOH, IOUT = 10mA
0
40
20
80
60
140
120
100
10 3020 40 50 60 70 80
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX13442-4E toc07
DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER OUTPUT CURRENT (mA)
MAX13442E
DI = GND, DE = VCC,
VOLTAGE APPLIED
TO OUTPUT A
RL = 54Ω
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
MAX13442-4E toc01
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
1109580655035205-10-25
1
2
3
4
5
6
0
-40 125
DRIVER AND RECEIVER
ENABLED
MAX13443E
DRIVER DISABLED,
RECEIVER ENABLED
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Maxim Integrated
│
6
www.maximintegrated.com
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
-40 -10 5 20-25 35 50 65 80 95 110 125
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
MAX13442-4E toc10
TEMPERATURE (°C)
DIFFERENTIAL OUTPUT VOLTAGE (V)
RL = 100Ω
RL = 54Ω
MAX13443E
0
30
20
10
40
50
60
70
80
90
100
-80 -50-65 -35 -20 -5
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX13442-4E toc08
DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER OUTPUT CURRENT (mA)
MAX13442E
DI = GND, DE = VCC,
VOLTAGE APPLIED
TO OUTPUT B
RL = 54Ω
-2000
-400
-1200
-1600
-800
1200
800
400
0
2800
2400
2000
1600
3200
A, B CURRENT vs. A, B
VOLTAGE (TO GROUND)
MAX13442-4E toc11
A, B VOLTAGE (V)
A, B CURRENT (A)
-80 -60 -40 0
-20 40 6020 80
DRIVER DISABLED,
RECEIVER ENABLED
MAX13442E
NO LOAD
RL = 54Ω
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
-40 -10 5 20-25 35 50 65 80 95 110 125
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
MAX13442-4E toc09
TEMPERATURE (°C)
DIFFERENTIAL OUTPUT VOLTAGE (V)
RL = 100Ω
RL = 54Ω
MAX13442E
-2000
-1200
-1600
0
-400
-800
400
800
1600
1200
2000
-60 -40 -30-50 -20 -10 0 10 20 30 40 6050
A, B CURRENT vs. A, B VOLTAGE
(TO GROUND)
MAX13442-4E toc12
A, B VOLTAGE (V)
A, B CURRENT (A)
DRIVER DISABLED,
RECEIVER ENABLED
MAX13443E
NO LOAD
RL = 54Ω
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Maxim Integrated
│
7
www.maximintegrated.com
Typical Operating Characteristics (continued)
Figure 1. Driver VOD and VOC
Figure 2. Receiver VOH and VOL
Figure 3. Driver Propagation Times
Figure 4. Driver Differential Output Delay and Transition Times
VCC
DVOD
VOC
2
RL
2
RL
DI
A
B
RRO
0
VOH IOH
(-)
IOL
(+)
VOL
VID
A
B
VCC
VOM
3V
0V
VOH
VOM
VOM
VOM
VOM
VOL
VOH
VOL
50Ω
RL
CL = 50pF
(NOTE 6)
GENERATOR
(NOTE 5)
D
DI tPLHA
1.5V
A
B
OUT
S1
DI 1.5V
tPHLA
tPHLB tPLHB
≈ 1.5V
VOH + VOL
2
VOM =
A
B
2
VCC
50Ω
RL
CL = 50pF (NOTE 6)
GENERATOR
(NOTE 5)
D
DI OUT
CL
CL
tDPLH tDPHL
tLH
50%
1.5V
10%
(A–B)
DI
90%
50%
1.5V
10%
90%
3V
0V
≈ 2.0V
tHL
≈ -2.0V
A
B
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
www.maximintegrated.com Maxim Integrated
│
8
Test Circuits and Waveforms
Figure 5. Driver Enable and Disable Times
Figure 6. Driver Enable and Disable Times
Figure 7. Receiver Propagation Delay
50Ω
GENERATOR
(NOTE 5)
≈ 1.5V
VOH + VOL
2
VOM =
3V
0V
VOH
VOM
0V
D0 OR 3V
tPDHS tPDHZ
1.5V
0.25V
A, B
A, B
S1
DE 1.5V
CL = 50pF
(NOTE 6)
RL = 500Ω
DI
A
B
DE
tPDZH
A, B
DE
VCC
3V
0V
VCC
VOL
VOM
tPDLS
1.5V
0.25V
1.5V
tPDLZ
50Ω
GENERATOR
(NOTE 5)
D0 OR 3V A, B
S1
CL = 50pF
(NOTE 6)
RL = 500Ω
DI
DE
A
B
tPDZL
50W
GENERATOR
(NOTE 5) CL = 20pF
(NOTE 6)
VID RRO
tRPLH
1.0V
RO
1.0V
0V
(A–B) 1.0V
2.0V
0V
tRPHL
VCC
VOM VOM
0V
A
B
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
www.maximintegrated.com Maxim Integrated
│
9
Test Circuits and Waveforms (continued)
Note 5: The input pulse is supplied by a generator with the following characteristics: f = 5MHz, 50% duty cycle; tr ≤ 6ns; Z0 = 50Ω.
Note 6: CL includes probe and stray capacitance.
Figure 8. Receiver Enable and Disable Times
50Ω
GENERATOR
(NOTE 5)
CL = 20pF
(NOTE 6)
VCC
3V
0V
VCC
VOL
R
+1.5V
-1.5V VID
1.5V
RO
S1
S2
1kΩ
RE 1.5V
S1 CLOSED
S2 OPEN
VS3 = -1.5V
tRPZL
tRPSL
3V
0V
VOH
0V
1.5V
RE 1.5V
S1 OPEN
S2 CLOSED
VS3 = 1.5V
tRPZH
tRPSH
tRPWAKE
3V
0V
VCC
VOL
0.5V
RO
RE 1.5V
S1 CLOSED
S2 OPEN
VS3 = -1.5V
tRPLZ
3V
0V
VOH
0V
0.5V
1.5V
RO
RE
S1 OPEN
S2 CLOSED
VS3 = 1.5V
tRPHZ
S3
RO
A
B
RO
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
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PIN
NAME FUNCTION
MAX13442E
MAX13443E MAX13444E
1 1 RO Receiver Output. If the receiver is enabled and (VA- VB) ≥ -50mV,
RO = high; if (VA - VB) ≤ -200mV, RO = low.
2 2 RE Receiver Output Enable. Pull RE low to enable RO.
3 — DE
Driver Output Enable. Force DE high to enable driver. Pull DE low
to three-state the driver output. Drive RE high and pull DE low to
enter low-power shutdown mode.
4 — DI
Driver Input. A logic-low on DI forces the noninverting output
low and the inverting output high. A logic-high on DI forces the
noninverting output high and the inverting output low.
5 5 GND Ground
6 6 A Noninverting Receiver Input/Driver Output
7 7 B Inverting Receiver Input/Driver Output
8 8 VCC
Positive Supply, VCC = +4.75V to +5.25V. For normal operation,
bypass VCC to GND with a 0.1µF ceramic capacitor. For full ESD
protection, bypass VCC to GND with 1µF ceramic capacitor.
— 3 DE
Driver Output Enable. Pull DE low to enable the outputs. Force DE
high to three-state the outputs. Drive RE and DE high to enter low-
power shutdown mode.
— 4 TXD
J1708 Input. A logic-low on TXD forces outputs A and B to the
dominant state. A logic-high on TXD forces outputs A and B to the
recessive state.
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
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Pin Description
X = Don’t care.
X = Don’t care.
X = Don’t care.
Table 1. MAX13442E/MAX13443E
(RS-485/RS-422)
Table 3. MAX13442E/MAX13443E
(RS-485/RS-422)
Table 2. MAX13444E (J1708) Application Table 4. MAX13444E (RS-485/RS-422)
TRANSMITTING
INPUTS OUTPUTS
RE DE DI A B
0 0 X High-Z High-Z
0 1 0 0 1
0 1 1 1 0
1 0 X Shutdown Shutdown
1 1 0 0 1
1 1 1 1 0
TRANSMITTING
INPUTS OUTPUTS CONDITIONS
TXD DE A B —
0 1 High-Z High-Z —
1 1 High-Z High-Z —
0 0 0 1 Dominant state
1 0 High-Z High-Z Recessive state
RECEIVING
INPUTS OUTPUTS
RE DE (VA - VB) RO
0 X ≥-0.05V 1
0 X ≤-0.2V 0
0 X Open/shorted 1
1 1 X High-Z
1 0 X Shutdown
RECEIVING
INPUTS OUTPUTS
RE DE (VA - VB) RO
0 X ≥-0.05V 1
0 X ≤-0.2V 0
0 X Open/shorted 1
1 0 X High-Z
1 1 X Shutdown
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MAX13444E
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Function Tables
Detailed Description
The MAX13442E/MAX13443E/MAX13444E fault-protect-
ed transceivers for RS-485/RS-422 and J1708 com-
munication 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 termi-
nated transmission line with all drivers disabled (see the
True Fail-Safe section). All devices have a hot-swap input
structure that prevents disturbances on the differential
signal lines when a circuit board is plugged into a hot
backplane (see the Hot-Swap Capability section). The
MAX13442E/MAX13444E feature a reduced slew-rate
driver that minimizes EMI and reduces reflections caused
by improperly terminated cables, allowing error-free data
transmission up to 250kbps (see the Reduced EMI and
Reflections section). The MAX13443E driver is not slew-
rate limited, allowing transmit speeds up to 10Mbps.
Driver
The driver accepts a single-ended, logic-level input (DI)
and transfers it to a differential, RS-485/RS-422 level
output (A and B). Deasserting the driver enable places
the driver outputs (A and B) into a high-impedance state.
Receiver
The receiver accepts a differential, RS-485/RS-422 level
input (A and B), and transfers it to a single-ended logic-
level output (RO). Deasserting the receiver enable places
the receiver inputs (A and B) into a high-impedance state
(see Table 1–Table 4).
Low-Power Shutdown
The MAX13442E/MAX13443E/MAX13444E offer a low-
power shutdown mode. Force DE low and RE high to shut
down the MAX13442E/MAX13443E. Force DE and RE
high to shut down the MAX13444E. A time delay of 50ns
prevents the device from accidentally entering shutdown
due to logic skews when switching between transmit and
receive modes. Holding DE low and RE high for at least
800ns guarantees that the MAX13442E/MAX13443E
enter shutdown. In shutdown, the devices consume a
maximum 20μA supply current.
±80V Fault Protection
The driver outputs/receiver inputs of RS-485 devices in
industrial network applications often experience voltage
faults resulting from shorts to the power grid that exceed
the -7V to +12V range specified in the EIA/TIA-485 stan-
dard. In these applications, ordinary RS-485 devices
(typical absolute maximum -8V to +12.5V) require costly
external protection devices. To reduce system complexity
and eliminate this need for external protection, the driver
outputs/receiver inputs of the MAX13442E/MAX13444E
withstand voltage faults up to ±80V (±60V for the
MAX13443E) with respect to ground without damage.
Protection is guaranteed regardless whether the device is
active, shut down, or without power.
True Fail-Safe
The MAX13442E/MAX13443E/MAX13444E use a -50mV
to -200mV differential input threshold to ensure true
fail-safe receiver inputs. This threshold guarantees the
receiver outputs a logic-high for shorted, open, or idle
data lines. The -50mV to -200mV threshold complies with
the ±200mV threshold EIA/TIA-485 standard.
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures are
incorporated on all pins to protect against ESD encoun-
tered during handling and assembly. The MAX13442E/
MAX13443E/MAX13444E receiver inputs/driver outputs
(A, B) have extra protection against static electricity found
in normal operation. Maxim’s engineers have developed
state-of-the-art structures to protect these pins against
±15kV ESD without damage. After an ESD event, the
MAX13442E/MAX13443E/MAX13444E continue working
without latchup.
ESD protection can be tested in several ways. The receiv-
er inputs are characterized for protection to ±15kV using
the Human Body Model.
ESD Test Conditions
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents test
setup, methodology, and results.
Human Body Model
Figure 9a shows the Human Body Model, and Figure 9b
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 device through a 1.5kΩ resistor.
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or bus contention. The
first, a foldback current limit on the driver output stage,
provides immediate protection against short circuits over
the whole common-mode voltage range. The second, a
thermal shutdown circuit, forces the driver outputs into
a high-impedance state if the die temperature exceeds
+160°C. Normal operation resumes when the die temper-
ature cools to +140°C, resulting in a pulsed output during
continuous short-circuit conditions.
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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Hot-Swap Capability
Hot-Swap Inputs
Inserting circuit boards into a hot, or powered, backplane
may cause voltage transients on DE, RE, and receiver
inputs A and B that can lead to data errors. For example,
upon initial circuit board insertion, the processor under-
goes a power-up sequence. During this period, the high-
impedance state of the output drivers makes them unable
to drive the MAX13442E/MAX13443E/MAX13444E
enable inputs to a defined logic level. Meanwhile, leakage
currents of up to 10μA from the high-impedance output, or
capacitively coupled noise from VCC or GND, could cause
an input to drift to an incorrect logic state. To prevent such
a condition from occurring, the MAX13442E/MAX13443E/
MAX13444E feature hot-swap input circuitry on DE, and
RE to guard against unwanted driver activation during
hot-swap situations. The MAX13444E has hot-swap input
circuitry only on RE. When VCC rises, an internal pulldown
(or pullup for RE) circuit holds DE low for at least 10μs,
and until the current into DE exceeds 200μA. After the
initial power-up sequence, the pulldown circuit becomes
transparent, resetting the hot-swap tolerable input.
Hot-Swap Input Circuitry
At the driver-enable input (DE), there are two NMOS
devices, M1 and M2 (Figure 10). When VCC ramps from
zero, an internal 15μs timer turns on M2 and sets the SR
latch, which also turns on M1. Transistors M2, a 2mA cur-
rent sink, and M1, a 100μA current sink, pull DE to GND
through a 5.6kΩ resistor. M2 pulls DE to the disabled
state against an external parasitic capacitance up to
100pF that may drive DE high. After 15μs, the timer deac-
tivates M2 while M1 remains on, holding DE low against
three-state leakage currents that may drive DE high. M1
remains on until an external current source overcomes
the required input current. At this time, the SR latch resets
M1 and turns off. When M1 turns off, DE reverts to a stan-
dard, high-impedance CMOS input. Whenever VCC drops
below 1V, the input is reset.
A complementary circuit for RE uses two PMOS devices
to pull RE to VCC.
Figure 9a. Human Body ESD Test Model
Figure 9b. Human Body Model Current Waveform Figure 10. Simplified Structure of the Driver Enable Pin (DE)
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
100pF
RC
1MΩ
RD
1.5kΩ
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
VCC
TIMER
TIMER
DE
(HOT SWAP)
15µs
100µA
M1 M2
5.6kΩ
2mA
IP 100%
90%
36.8%
tRL TIME
tDL
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
10%
0
0
AMPERES
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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Applications Information
128 Transceivers on the Bus
The MAX13442E/MAX13443E/MAX13444E transceivers
1/4-unit-load receiver input impedance (48kΩ) allows up
to 128 transceivers connected in parallel on one commu-
nication line. Connect any combination of these devices,
and/or other RS-485 devices, for a maximum of 32-unit
loads to the line.
Reduced EMI and Reections
The MAX13442E/MAX13444E are slew-rate limited, mini-
mizing EMI and reducing reflections caused by improp-
erly terminated cables. Figure 11 shows the driver output
waveform and its Fourier analysis of a 125kHz signal
transmitted by a MAX13443E. High-frequency harmonic
components with large amplitudes are evident.
Figure 12 shows the same signal displayed for the
MAX13442E transmitting under the same conditions.
Figure 12’s high-frequency harmonic components are
much lower in amplitude, compared with Figure 11’s, and
the potential for EMI is significantly reduced.
In general, a transmitter’s rise time relates directly to the
length of an unterminated stub that can be driven with
only minor waveform reflections. The following equation
expresses this relationship conservatively:
length = tRISE/(10 x 1.5ns/ft)
where tRISE is the transmitter’s rise time.
For example, the MAX13442E’s rise time is typically
800ns, which results in excellent waveforms with a stub
length up to 53ft. A system can work well with longer
unterminated stubs, even with severe reflections, if the
waveform settles out before the UART samples them.
RS-485 Applications
The MAX13442E/MAX13443E/MAX13444E transceivers
provide bidirectional data communications on multipoint
bus transmission lines. Figure 13 shows a typical net-
work application circuit. The RS-485 standard covers line
lengths up to 4000ft. To minimize reflections and reduce
data errors, terminate the signal line at both ends in its
characteristic impedance, and keep stub lengths off the
main line as short as possible.
Figure 11. Driver Output Waveform and FFT Plot of the
MAX13443E Transmitting a 125kHz Signal
Figure 12. Driver Output Waveform and FFT Plot of the
MAX13442E Transmitting a 125kHz Signal
5.00MHz500kHz/div0
20dB/div
2V/div
5.00MHz500kHz/div0
20dB/div
2V/div
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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J1708 Applications
The MAX13444E is designed for J1708 applications. To
configure the MAX13444E, connect DE and RE to GND.
Connect the signal to be transmitted to TXD. Terminate
the bus with the load circuit as shown in Figure 14. The
drivers used by SAE J1708 are used in a dominant-mode
application. DE is active low; a high input on DE places
the outputs in high impedance. When the driver is dis-
abled (TXD high or DE high), the bus is pulled high by
external bias resistors R1 and R2. Therefore, a logic-level
high is encoded as recessive. When all transceivers are
idle in this configuration, all receivers output logic-high
because of the pullup resistor on A and pulldown resistor
on B. R1 and R2 provide the bias for the recessive state.
C1 and C2 combine to form a lowpass filter, effective for
reducing FM interference. R2, C1, R4, and C2 combine
to form a 1.6MHz lowpass filter, effective for reducing AM
interference. Because the bus is unterminated, at high
frequencies, R3 and R4 perform a pseudotermination.
This makes the implementation more flexible, as no spe-
cific termination nodes are required at the ends of the bus.
Figure 13. MAX13442E/MAX13443E Typical RS-485 Network
DI RO DE
A
B
RE
RO
RO
RO
DI
DI
DI
DE
DE
DE
DD
D
R
R
R
B B
B
AA
A
120Ω120Ω
D
R
MAX13442E
MAX13443E
RERE
RE
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
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Figure 14. J1708 Application Circuit (See Tables 2 and 4)
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 SO S8+4 21-0041 90-0096
R1
4.7kΩ
R3
47Ω
C1
2.2nF
C2
2.2nF
R2
4.7kΩ
RO
RX
TX
R4
47Ω
J1708 BUS
A
B
TXD D
R
DE
RE
MAX13444E
VCC
1
2
3
4
8
5
VCC
GND
TXD
DE
RE
RO R
D
RT
RT
7
6
D
R
DE
RE
TXD
RO
A
B
1
2
3
4
8
7
6
5
VCC
B
A
GND
TXD
DE
RE
RO
SO SO
R
D
B
A
MAX13444E
++
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.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.
Chip Information
PROCESS: BiCMOS
Pin Congurations and Typical Operating Circuits (continued)
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 10/05 Initial release —
1 3/06
Corrected the part numbers in the conditions for ΔVOC in the DC Electrical
Characteristics table; corrected the A, B current units from mA to FA for the A, B Current
vs. A, B Voltage (to Ground) graphs in the Typical Operating Characteristics section
2, 7
2 11/10 Added lead(Pb)-free parts to the Ordering Information table; added the soldering
temperature to the Absolute Maximum Ratings section; updated Table 2 outputs 1, 2, 12
3 3/11 Added an automotive qualied part to the Ordering Information; added the Package
Thermal Characteristics section 1, 2
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
© 2011 Maxim Integrated Products, Inc.
│
18
Revision History
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