MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
General Description
Features
●●
●●
●●
●●
●●
●●
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 errorfree 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 differential line receiver with three-state input. The 1/4-unitload receiver input impedance allows up to 128 transceivers on a single bus. The devices operate from a 5V supply. True fail-safe inputs guarantee a logic-high receiver
output when the receiver inputs are open, shorted, or
connected to an idle data line.
●●
●●
●●
●●
±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
●● RS-422/RS-485
Communications
●● Truck and Trailer
Applications
●● Industrial Networks
Hot-swap circuitry eliminates false transitions on the data
bus during circuit initialization or connection to a live backplane. Short-circuit current-limiting and thermal-shutdown
circuitry protect the driver against excessive power dissipation, and on-chip ±15kV ESD protection eliminates
costly external protection devices.
Ordering Information
PART
The MAX13442E/MAX13443E/MAX13444E are available
in an 8-pin SO package and are specified over the automotive temperature range.
MAX13442E
RS-485
MAX13443E
RS-485
10
±60
MAX13444E
J1708
0.25
±80
8 SO
MAX13443EASA+
-40°C to +125°C
8 SO
MAX13444EASA/V+T
-40°C to +125°C
8 SO
RECEIVER/DRIVER
ENABLE
Yes
TRANSCEIVERS
ON BUS
128
Yes
Yes
128
Yes
Yes
Yes
128
Yes (only RE)
Pin Configurations and Typical Operating Circuits
TOP VIEW
RO
1
+
R
RE 2
DE 3
DI 4
D
SO
RO
1
8
VCC
7
B
RE 2
6
A
DE
5
GND
+
R
8 VCC
7 B
RT
6
A
5 GND
3
DI 4
D
SO
DE
MAX13442E
MAX13443E
Pin Configurations and Typical Operating Circuits continued at end of data sheet.
19-3898; Rev 3; 3/11
PIN-PACKAGE
-40°C to +125°C
DATA RATE
FAULT
LOW-POWER
(Mbps)
PROTECTION (V) SHUTDOWN
0.25
±80
Yes
TYPE
TEMP RANGE
MAX13442EASA+
+Denotes lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
T = Tape and reel.
Selector Guide
PART
●● Telecommunications
Systems
●● Automotive Applications
●● HVAC Controls
RT
D
B
A
DI
RO
R
RE
HOT SWAP
Yes
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Absolute Maximum Ratings
(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
Note 1: During normal operation, a termination resistor must be connected between A and B in order to guarantee overvoltage protection 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.
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 (Note 2)
SO
Junction-to-Ambient Thermal Resistance (θJA).........132°C/W
Junction-to-Case Thermal Resistance (θJC)................38°C/W
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.
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
DRIVER
Differential Driver Output
Change in Magnitude of
Differential Output Voltage
Driver Common-Mode
Output Voltage
Change in Magnitude of
Common-Mode Voltage
VOD
ΔVOD
VOC
DVOC
Figure 1, RL = 100Ω
2
VCC
Figure 1, RL = 54Ω
1.5
VCC
Figure 1, RL = 100Ω or 54Ω (Note 3)
Figure 1, RL = 100Ω or 54Ω
VCC/2
Figure 1, RL = 100Ω or 54Ω (Note 3)
(MAX13442E/MAX13443E)
V
0.2
V
3
V
0.2
V
DRIVER LOGIC
Driver-Input High Voltage
VDIH
Driver-Input Low Voltage
VDIL
0.8
V
Driver-Input Current
IDIN
±2
µA
Driver Short-Circuit Output
Current (Note 4)
IOSD
Driver Short-Circuit Foldback
Output Current
IOSDF
Driver-Limit Short-Circuit
Foldback Output Current
IOSDL
www.maximintegrated.com
2
0V ≤ VOUT ≤ +12V
+350
-7V ≤ VOUT ≤ VCC
-350
(VCC - 1V) ≤ VOUT ≤ +12V (Note 4)
+25
-7V ≤ VOUT ≤ +1V (Note 4)
VOUT ≥ +20V, RL = 100Ω
VOUT ≤ -15V, RL = 100Ω
V
-25
+6
-6
mA
mA
mA
Maxim Integrated │ 2
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RECEIVER
Input Current
Receiver-Differential Threshold
Voltage
Receiver-Input Hysteresis
IA,B
VTH
A, B
receive
mode
VCC = GND, VA, B = 12V
250
VA, B = -7V
-150
VA, B = ±80V
-7V ≤ VCM ≤ +12V
-200
ΔVTH
µA
±6
mA
-50
mV
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
Receiver Output Short-Circuit
Current
IOSR
0V ≤ VRO ≤ VCC
VCIH
DE, DE, RE
48
kΩ
±95
mA
CONTROL
Control-Input High Voltage
Input-Current Latch During First
Rising Edge
IIN
2
DE, RE
V
90
µA
SUPPLY CURRENT
Normal Operation
Supply Current in Shutdown
Mode
Supply Current with Output
Shorted to ±60V
www.maximintegrated.com
ICC
ISHDN
ISHRT
No load,
DI = VCC
or GND
DE = VCC, RE = GND
(MAX13442E)
(DE = RE = GND)
(MAX13444E)
30
(DE = VCC, RE = GND)
(MAX13443E)
10
mA
DE = GND, RE = VCC
(MAX13442E/MAX13443E)
20
DE = GND, RE = VCC, TA = +25°C
(MAX13442E/MAX13443E)
10
DE = RE = VCC (MAX13444E)
100
DE = RE = VCC, TA = +25°C (MAX13444E)
10
DE = GND, RE = GND, no load
output in three-state (MAX13443E)
±15
µA
mA
Maxim Integrated │ 3
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Protection Specifications
(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
MAX13442E/
A, B; RSOURCE = 0Ω, MAX13444E
RL = 54Ω
MAX13443E
Overvoltage Protection
ESD Protection
A, B
MIN
TYP
MAX
±80
UNITS
V
±60
±15
Human Body Model
kV
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.)
PARAMETER
SYMBOL
CONDITIONS
Driver Propagation Delay
tPLHA,
tPLHB
Figure 3, RL = 54Ω, CL = 50pF (MAX13442E)
Driver Differential Propagation Delay
tDPLH,
tDPHL
RL = 54Ω, CL = 50pF, Figure 4
Driver Differential Output
Transition Time
tLH,tHL
RL = 54Ω, CL = 50pF, Figure 4
Driver Output Skew
Differential Driver Output Skew
MIN
RDIFF = 60Ω, CDIFF = 100pF (MAX13444E)
200
RL = 54Ω, CL = 50pF,
tSKEWAB,
t
= |tPLHA - tPHLB|,
tSKEWBA SKEWAB
tSKEWBA = |tPLHB - tPHLA|
tDSKEW
RL = 54Ω, CL = 50pF,
tDSKEW = |tDPLH - tDPHL|
TYP
MAX
UNITS
2000
ns
2000
ns
2000
ns
350
ns
200
ns
Maximum Data Rate
fMAX
250
kbps
Driver Enable Time to Output High
tPDZH
RL = 500Ω, CL = 50pF, Figure 5
2000
ns
Driver Disable Time from Output High
tPDHZ
RL = 500Ω, CL = 50pF, Figure 5
2000
ns
Driver Enable Time from Shutdown to
Output High
tPDHS
RL = 500Ω, CL = 50pF, Figure 5
4.2
µs
Driver Enable Time to Output Low
tPDZL
RL = 500Ω, CL = 50pF, Figure 6
2000
ns
Driver Disable Time from Output Low
tPDLZ
RL = 500Ω, CL = 50pF, Figure 6
2000
ns
Driver Enable Time from Shutdown to
Output Low
tPDLS
RL = 500Ω, CL = 50pF, Figure 6
4.2
µs
Driver Time to Shutdown
tSHDN
RL = 500Ω, CL = 50pF
800
ns
Receiver Propagation Delay
tRPLH,
tRPHL
CL = 20pF, VID = 2V, VCM = 0V, Figure 7
2000
ns
Receiver Output Skew
tRSKEW
CL = 20pF, tRSKEW = |tRPLH - tRPHL|
200
ns
Receiver Enable Time to Output High
tRPZH
RL = 1kΩ, CL = 20pF, Figure 8
2000
ns
Receiver Disable Time from Output High
tRPHZ
RL = 1kΩ, CL = 20pF, Figure 8
2000
ns
4.2
µs
Receiver Wake Time from Shutdown
tRPWAKE RL = 1kΩ, CL = 20pF, Figure 8
Receiver Enable Time to Output Low
tRPZL
RL = 1kΩ, CL = 20pF, Figure 8
2000
ns
Receiver Disable Time from Output Low
tRPLZ
RL = 1kΩ, CL = 20pF, Figure 8
2000
ns
Receiver Time to Shutdown
tSHDN
RL = 500Ω, CL = 50pF
800
ns
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Maxim Integrated │ 4
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Switching Characteristics (MAX13443E)
(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
MAX
UNITS
RL = 27Ω, CL = 50pF, Figure 3
60
ns
tDPLH,
tDPHL
RL = 54Ω, CL = 50pF, Figure 4
60
ns
tLH,tHL
RL = 54Ω, CL = 50pF, Figure 4
25
ns
10
ns
10
ns
Driver Propagation Delay
tPLHA,
tPLHB
Driver Differential Propagation Delay
Driver Differential Output
Transition Time
Driver Output Skew
Differential Driver Output Skew
CONDITIONS
MIN
R = 54Ω, CL = 50pF,
tSKEWAB, L
t
= |tPLHA - tPHLB|,
tSKEWBA SKEWAB
tSKEWBA = |tPLHB - tPHLA|
tDSKEW
RL = 54Ω, CL = 50pF,
tDSKEW = |tDPLH - tDPHL|
TYP
Maximum Data Rate
fMAX
Driver Enable Time to Output High
tPDZH
RL = 500Ω, CL = 50pF, Figure 5
1200
ns
Driver Disable Time from Output High
tPDHZ
RL = 500Ω, CL = 50pF, Figure 5
1200
ns
Driver Enable Time from Shutdown to
Output High
tPDHS
RL = 500Ω, CL = 50pF, Figure 5
4.2
µs
Driver Enable Time to Output Low
tPDZL
RL = 500Ω, CL = 50pF, Figure 6
1200
ns
Driver Disable Time from Output Low
tPDLZ
RL = 500Ω, CL = 50pF, Figure 6
1200
ns
Driver Enable Time from Shutdown to
Output Low
tPDLS
RL = 500Ω, CL = 50pF, Figure 6
4.2
Fs
Driver Time to Shutdown
tSHDN
RL = 500Ω, CL = 50pF, Figure 6
800
ns
Receiver Propagation Delay
tRPLH,
tRPHL
CL = 20pF, VID = 2V, VCM = 0V, Figure 7
85
ns
CL = 20pF, tRSKEW = |tRPLH - tRPHL|
15
ns
tRPZH
RL = 1kΩ, CL = 20pF, Figure 8
400
ns
tRPHZ
RL = 1kΩ, CL = 20pF, Figure 8
400
ns
tRPWAKE RL = 1kΩ, CL = 20pF, Figure 8
4.2
µs
Receiver Output Skew
Receiver Enable Time to Output High
Receiver Disable Time from Output High
Receiver Wake Time from Shutdown
tRSKEW
10
Mbps
Receiver Enable Wake Time from
Shutdown
tRPSH
RL = 1kΩ, CL = 20pF, Figure 8
400
ns
Receiver Disable Time from Output Low
tRPLZ
RL = 1kΩ, CL = 20pF, Figure 8
400
ns
Receiver Time to Shutdown
tSHDN
RL = 500Ω, CL = 50pF
800
ns
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.
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Maxim Integrated │ 5
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
DRIVER DISABLED,
RECEIVER ENABLED
2
16
12
1
8
4
MAX13443E
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
0
DRIVER DISABLED,
RECEIVER ENABLED
MAX13442E/MAX13444E
25
20
15
10
5
0
RECEIVER OUTPUT VOLTAGE (V)
MAX13442-4E toc03
40
60
25
20
15
10
5
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT LOW VOLTAGE (V)
VOH, IOUT = 10mA
2.5
2.0
1.5
VOL, IOUT = -10mA
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
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80 100 120
MAX13442-4E toc05
30
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
3.0
0
20
RECEIVER OUTPUT VOLTAGE
vs. TEMPERATURE
3.5
0.5
0
OUTPUT LOW VOLTAGE (V)
4.5
1.0
-40 -20
35
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
5.0
4.0
0.00001
40
140
DRIVER OUTPUT CURRENT (mA)
0
0.0001
TEMPERATURE (°C)
RECEIVER OUTPUT CURRENT (mA)
MAX13442-4E toc04
30
0.001
RECEIVER OUTPUT CURRENT
vs. OUTPUT-HIGH VOLTAGE
MAX13442-4E toc06
RECEIVER OUTPUT CURRENT (mA)
35
0.01
TEMPERATURE (°C)
RECEIVER OUTPUT CURRENT
vs. OUTPUT-LOW VOLTAGE
40
MAX13442E
DI = DE = GND
RE = VCC
0.1
0.000001
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
1
RL = 54Ω
MAX13442E
DI = GND, DE = VCC,
VOLTAGE APPLIED
TO OUTPUT A
120
100
MAX13442-4E toc07
3
DRIVER AND RECEIVER
ENABLED
10
SHUTDOWN SUPPLY CURRENT (µA)
4
24
20
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
MAX13442-4E toc02
DRIVER AND RECEIVER
ENABLED
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
5
MAX13442-4E toc01
6
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
80
60
40
20
0
10
20
30
40
50
60
70
80
DIFFERENTIAL OUTPUT VOLTAGE (V)
Maxim Integrated │ 6
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
MAX13442E
DI = GND, DE = VCC,
VOLTAGE APPLIED
TO OUTPUT B
70
60
50
40
30
20
10
0
-80
-65
-50
-35
-20
3.0
2.0
RL = 54Ω
1.5
1.0
0.5
0
-5
RL = 100Ω
2.5
MAX13442E
-40 -25 -10 5 20 35 50 65 80 95 110 125
DIFFERENTIAL OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
3.0
MAX13442-4E toc10
RL = 100Ω
2.5
2.0
A, B CURRENT (A)
DIFFERENTIAL OUTPUT VOLTAGE (V)
3.5
RL = 54Ω
1.5
1.0
0.5
0
MAX13443E
-40 -25 -10 5 20 35 50 65 80 95 110 125
A, B CURRENT vs. A, B
VOLTAGE (TO GROUND)
3200
2800
2400
2000
1600
1200
800
400
0
-400
-800
-1200
-1600
-2000
MAX13442-4E toc11
80
3.5
MAX13442-4E toc09
RL = 54Ω
DIFFERENTIAL OUTPUT VOLTAGE (V)
90
MAX13442-4E toc08
DRIVER OUTPUT CURRENT (mA)
100
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
DRIVER DISABLED,
RECEIVER ENABLED
NO LOAD
RL = 54Ω
MAX13442E
-80 -60
TEMPERATURE (°C)
-40
-20
0
20
40
60
80
A, B VOLTAGE (V)
2000
1600
MAX13442-4E toc12
A, B CURRENT vs. A, B VOLTAGE
(TO GROUND)
DRIVER DISABLED,
RECEIVER ENABLED
A, B CURRENT (A)
1200
800
400
0
NO LOAD
-400
-800
RL = 54Ω
-1200
-1600
-2000
MAX13443E
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60
A, B VOLTAGE (V)
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Maxim Integrated │ 7
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Test Circuits and Waveforms
RL
2
A
DI
VOD
D
B
RL
VCC
VOC
2
Figure 1. Driver VOD and VOC
A
VID
RO
R
B
0
VOL
IOL
(+)
VOH
IOH
(-)
Figure 2. Receiver VOH and VOL
3V
VOM
A
DI
GENERATOR
(NOTE 5)
S1
B
CL = 50pF
(NOTE 6)
VCC
VOM =
1.5V
1.5V
0V
tPLHA
OUT
D
50Ω
DI
RL
2
tPHLA
VOH
VOM
A
VOM
VOL
tPHLB
VOH + VOL
≈ 1.5V
2
tPLHB
VOH
B
VOM
VOM
VOL
Figure 3. Driver Propagation Times
3V
DI
GENERATOR
(NOTE 5)
50Ω
A
D
RL
B
0V
OUT
(A–B)
CL = 50pF (NOTE 6)
tDPHL
tDPLH
VCC
CL
1.5V
1.5V
DI
CL
50%
10%
tLH
90%
90%
≈ 2.0V
50%
10%
≈ -2.0V
tHL
Figure 4. Driver Differential Output Delay and Transition Times
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Maxim Integrated │ 8
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Test Circuits and Waveforms (continued)
0 OR 3V
DI
A
DE
GENERATOR
(NOTE 5)
3V
S1
A, B
D
B
DE
RL = 500Ω
CL = 50pF
(NOTE 6)
1.5V
1.5V
tPDZH
tPDHS
0V
tPDHZ
50Ω
A, B
VOM =
0.25V
VOM
VOH + VOL
≈ 1.5V
2
VOH
0V
Figure 5. Driver Enable and Disable Times
VCC
0 OR 3V
A
DI
GENERATOR
(NOTE 5)
RL = 500Ω
S1
tPDLS
B
CL = 50pF
(NOTE 6)
1.5V
1.5V
tPDZL
DE
A, B
D
DE
3V
0V
tPDLZ
VCC
A, B
50Ω
VOM
0.25V
VOL
Figure 6. Driver Enable and Disable Times
A
GENERATOR
(NOTE 5)
VID
50W
R
B
2.0V
RO
(A–B)
CL = 20pF
(NOTE 6)
1.0V
1.0V
0V
tRPLH
tRPHL
VCC
1.0V
0V
RO
VOM
VOM
0V
Figure 7. Receiver Propagation Delay
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Maxim Integrated │ 9
MAX13442E/MAX13443E/
MAX13444E
S3
+1.5V
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
S1
A
VID
-1.5V
R
RO
VCC
1kΩ
S2
B
GENERATOR
(NOTE 5)
CL = 20pF
(NOTE 6)
50Ω
3V
RE
1.5V
0V
tRPZH
tRPSH
tRPWAKE
RO
S1 OPEN
S2 CLOSED
VS3 = 1.5V
3V
RE
1.5V
VOH
VCC
RO
1.5V
1.5V
0V
3V
RE
1.5V
0V
VOL
S1 OPEN
S2 CLOSED
VS3 = 1.5V
3V
RE
1.5V
0V
tRPHZ
RO
0.5V
tRPLZ
VOH
RO
0V
0V
tRPZL
tRPSL
S1 CLOSED
S2 OPEN
VS3 = -1.5V
S1 CLOSED
S2 OPEN
VS3 = -1.5V
VCC
0.5V
VOL
Figure 8. Receiver Enable and Disable Times
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.
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Maxim Integrated │ 10
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Pin Description
PIN
NAME
FUNCTION
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
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 lowpower 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
1
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Ground
Maxim Integrated │ 11
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Function Tables
Table 1. MAX13442E/MAX13443E
(RS-485/RS-422)
Table 3. MAX13442E/MAX13443E
(RS-485/RS-422)
TRANSMITTING
RECEIVING
INPUTS
RE
OUTPUTS
DE
DI
A
B
RE
0
0
X
High-Z
High-Z
0
1
0
0
0
1
1
1
1
0
X
1
1
1
1
INPUTS
OUTPUTS
DE
(VA - VB)
RO
0
X
≥-0.05V
1
1
0
X
≤-0.2V
0
0
0
X
Open/shorted
1
Shutdown
Shutdown
1
1
X
High-Z
0
0
1
1
0
X
Shutdown
1
1
0
X = Don’t care.
X = Don’t care.
Table 2. MAX13444E (J1708) Application
Table 4. MAX13444E (RS-485/RS-422)
TRANSMITTING
INPUTS
OUTPUTS
RECEIVING
CONDITIONS
INPUTS
OUTPUTS
TXD
DE
A
B
—
RE
DE
(VA - VB)
RO
0
1
High-Z
High-Z
—
0
X
≥-0.05V
1
1
1
High-Z
High-Z
—
0
X
≤-0.2V
0
0
0
0
1
Dominant state
0
X
Open/shorted
1
1
0
High-Z
High-Z
Recessive state
1
0
X
High-Z
1
1
X
Shutdown
X = Don’t care.
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Maxim Integrated │ 12
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Detailed Description
The MAX13442E/MAX13443E/MAX13444E fault-protected transceivers for RS-485/RS-422 and J1708 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
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 slewrate 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 logiclevel 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 lowpower 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 standard. 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
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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 encountered 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 receiver 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 temperature cools to +140°C, resulting in a pulsed output during
continuous short-circuit conditions.
Maxim Integrated │ 13
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Hot-Swap Capability
Hot-Swap Input Circuitry
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 undergoes a power-up sequence. During this period, the highimpedance 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.
RC
1MΩ
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
Cs
100pF
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 current 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 deactivates 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 standard, 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.
RD
1.5kΩ
DISCHARGE
RESISTANCE
VCC
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
15µs
TIMER
TIMER
Figure 9a. Human Body ESD Test Model
IP 100%
90%
Ir
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
DE
(HOT SWAP)
5.6kΩ
AMPERES
100µA
36.8%
10%
0
M1
0
tRL
M2
TIME
tDL
CURRENT WAVEFORM
Figure 9b. Human Body Model Current Waveform
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2mA
Figure 10. Simplified Structure of the Driver Enable Pin (DE)
Maxim Integrated │ 14
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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 communication 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 Reflections
The MAX13442E/MAX13444E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly 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.
0
500kHz/div
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 network 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.
20dB/div
20dB/div
2V/div
2V/div
5.00MHz
Figure 11. Driver Output Waveform and FFT Plot of the
MAX13443E Transmitting a 125kHz Signal
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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:
0
500kHz/div
5.00MHz
Figure 12. Driver Output Waveform and FFT Plot of the
MAX13442E Transmitting a 125kHz Signal
Maxim Integrated │ 15
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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 disabled (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 specific termination nodes are required at the ends of the bus.
120Ω
120Ω
DE
B
B
DI
D
D
DI
DE
RO
A
B
A
B
A
A
R
R
RO
RE
RE
R
R
D
D
MAX13442E
MAX13443E
DI
DE
RO RE
DI
DE
RO RE
Figure 13. MAX13442E/MAX13443E Typical RS-485 Network
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Maxim Integrated │ 16
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Chip Information
PROCESS: BiCMOS
DE
TX
D
TXD
B
R1
4.7kΩ
R3
47Ω
C1
2.2nF
A
J1708 BUS
R4
47Ω
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 SO
S8+4
21-0041
90-0096
R2
4.7kΩ
R
RO
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.
C2
2.2nF
MAX13444E
RX
Package Information
VCC
RE
Figure 14. J1708 Application Circuit (See Tables 2 and 4)
Pin Configurations and Typical Operating Circuits (continued)
DE
+
+
VCC
RO 1
RE 2
7
B
RE 2
7 B
DE 3
6
A
DE 3
6
5
GND
TXD
4
R
D
SO
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TXD 4
MAX13444E
8 VCC
8
RO 1
R
A
5 GND
D
SO
RT
D
RT
TXD
B
A
RO
R
RE
Maxim Integrated │ 17
MAX13442E/MAX13443E/
MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Revision History
REVISION
NUMBER
REVISION
DATE
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
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
3
3/11
Added an automotive qualified part to the Ordering Information; added the Package
Thermal Characteristics section
DESCRIPTION
—
2, 7
1, 2, 12
1, 2
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
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 specifications 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.
© 2011 Maxim Integrated Products, Inc. │ 18