19-3898; Rev 3; 3/11
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Features
♦ ±15kV ESD Protection
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 tranceiver 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.
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.
The MAX13442E/MAX13443E/MAX13444E are available in an 8-pin SO package and are specified over the
automotive temperature range.
♦ ±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
Ordering Information
PART
Applications
RS-422/RS-485
Communications
Truck and Trailer
Applications
Industrial Networks
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
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
T = Tape and reel.
Telecommunications
Systems
Automotive Applications
HVAC Controls
Selector Guide
FAULT
PROTECTION
(V)
PART
TYPE
DATA RATE
(Mbps)
MAX13442E
RS-485
0.25
±80
Yes
Yes
128
Yes
MAX13443E
RS-485
10
±60
Yes
Yes
128
Yes
MAX13444E
J1708
0.25
±80
Yes
Yes
128
Yes (only RE)
LOW-POWER RECEIVER/DRIVER
SHUTDOWN
ENABLE
TRANSCEIVERS
ON BUS
HOT SWAP
Pin Configurations and Typical Operating Circuits
TOP VIEW
DE
+
+
RO
1
8
VCC
RO
RE
2
7
B
RE 2
DE 3
6
A
DE
3
5
GND
DI
4
DI
4
R
D
SO
1
R
8 VCC
7 B
RT
6
A
5 GND
D
SO
MAX13442E
MAX13443E
D
DI
B
RT
A
RO
R
RE
Pin Configurations and Typical Operating Circuits continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX13442E/MAX13443E/MAX13444E
General Description
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 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.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
VOD
VOC
VOC
Figure 1, RL = 100
2
VCC
Figure 1, RL = 54
1.5
VCC
Figure 1, RL = 100 or 54 (Note 3)
Figure 1, RL = 100 or 54
VCC / 2
Figure 1, RL = 100 or 54 (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
Driver-Input Current
IDIN
Driver Short-Circuit Output Current
(Note 4)
I OSD
Driver Short-Circuit Foldback
Output Current
I OSDF
Driver-Limit Short-Circuit Foldback
Output Current
I OSDL
2
2
0V VOUT +12V
V
±2
μA
+350
-7V VOUT VCC
-350
(VCC - 1V) VOUT +12V (Note 4)
+25
-7V VOUT +1V (Note 4)
VOUT +20V, RL = 100
V
0.8
-25
+6
VOUT -15V, RL = 100
_______________________________________________________________________________________
-6
mA
mA
mA
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
MAX13442E/MAX13443E/MAX13444E
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
IA,B
Receiver-Differential Threshold
Voltage
Receiver-Input Hysteresis
VTH
A, B
receive
mode
VCC = GND, VA, B = 12V
250
VA, B = -7V
-150
VA, B = ±80V
-7V VCM +12V
-200
VTH
μA
±6
mA
-50
mV
25
mV
RECEIVER LOGIC
Output-High Voltage
VOH
Figure 2, I OH = -1.6mA
VCC - 0.6
V
Output-Low Voltage
VOL
Figure 2, I OL = 1mA
0.4
V
Three-State Output Current at
Receiver
I OZR
0V VA, B VCC
±1
μA
Receiver Input Resistance
RIN
-7V VCM +12V
Receiver Output Short-Circuit
Current
I OSR
0V VRO VCC
VCIH
DE, DE, RE
48
k
±95
mA
CONTROL
Control-Input High Voltage
Input-Current Latch During First
Rising Edge
I IN
DE, RE
ICC
DE = VCC, RE = GND (MAX13442E)
No load, (DE = RE = GND) (MAX13444E)
DI = VCC
(DE = VCC, RE = GND)
or GND
(MAX13443E)
2
V
90
μA
SUPPLY CURRENT
Normal Operation
Supply Current in Shutdown Mode
I SHDN
10
20
DE = GND, RE = VCC, TA = +25°C
(MAX13442E/MAX13443E)
10
DE = RE = VCC, TA = +25°C (MAX13444E)
I SHRT
mA
DE = GND, RE = VCC
(MAX13442E/MAX13443E)
DE = RE = VCC (MAX13444E)
Supply Current with Output Shorted
to ±60V
30
DE = GND, RE = GND, no load
output in three-state (MAX13443E)
μA
100
10
±15
mA
_______________________________________________________________________________________
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
A, B; RSOURCE = 0,
RL = 54
Overvoltage Protection
ESD Protection
A, B
MIN
MAX13442E/
MAX13444E
±80
MAX13443E
±60
TYP
MAX
UNITS
V
±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
MIN
TYP
RDIFF = 60Ω, CDIFF = 100pF (MAX13444E)
200
MAX
UNITS
2000
ns
2000
ns
2000
ns
Driver Output Skew
tSKEWAB,
tSKEWBA
RL = 54Ω, CL = 50pF,
tSKEWAB = |tPLHA - tPHLB|,
tSKEWBA = |tPLHB - tPHLA|
350
ns
Differential Driver Output Skew
tDSKEW
RL = 54Ω, CL = 50pF,
tDSKEW = |tDPLH - tDPHL|
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
Receiver Wake Time from Shutdown
tRPWAKE
RL = 1kΩ, CL = 20pF, Figure 8
4.2
µs
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
4
_______________________________________________________________________________________
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
(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
RL = 54Ω, CL = 50pF,
tSKEWAB = |tPLHA - tPHLB|,
tSKEWBA = |tPLHB - tPHLA|
10
ns
RL = 54Ω, CL = 50pF,
tDSKEW = |tDPLH - tDPHL|
10
ns
Driver Propagation Delay
tPLHA,
tPLHB
Driver Differential Propagation Delay
Driver Differential Output
Transition Time
tSKEWAB,
tSKEWBA
Driver Output Skew
Differential Driver Output Skew
tDSKEW
CONDITIONS
MIN
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
tPDLS
RL = 500Ω, CL = 50pF, Figure 6
4.2
µs
Driver Enable Time from Shutdown to
Output Low
Driver Time to Shutdown
10
Mbps
tSHDN
RL = 500Ω, CL = 50pF, Figure 6
800
ns
Receiver Propagation Delay
tRPLH,
tRPHL
CL = 20pF, VID = 2V, VCM = 0V, Figure 7
85
ns
Receiver Output Skew
tRSKEW
CL = 20pF, tRSKEW = |tRPLH - tRPHL|
15
ns
Receiver Enable Time to Output High
tRPZH
RL = 1kΩ, CL = 20pF, Figure 8
400
ns
Receiver Disable Time from Output High
tRPHZ
RL = 1kΩ, CL = 20pF, Figure 8
400
ns
tRPWAKE
RL = 1kΩ, CL = 20pF, Figure 8
4.2
µs
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
Receiver Wake Time from Shutdown
Receiver Enable Wake Time from
Shutdown
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.
_______________________________________________________________________________________
5
MAX13442E/MAX13443E/MAX13444E
SWITCHING CHARACTERISTICS (MAX13443E)
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
4
DRIVER DISABLED,
RECEIVER ENABLED
2
16
12
8
DRIVER DISABLED,
RECEIVER ENABLED
4
1
MAX13443E
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
0.00001
-40 -20
0
20
40
25
20
15
10
MAX13442-4E toc05
30
RECEIVER OUTPUT CURRENT (mA)
35
35
30
25
20
15
10
5
0
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 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)
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT VOLTAGE
vs. TEMPERATURE
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
4.5
VOH, IOUT = 10mA
3.5
3.0
2.5
2.0
1.5
VOL, IOUT = -10mA
RL = 54Ω
140
DRIVER OUTPUT CURRENT (mA)
5.0
MAX13442-4E toc06
0
RECEIVER OUTPUT VOLTAGE (V)
0.0001
40
5
MAX13442E
DI = GND, DE = VCC,
VOLTAGE APPLIED
TO OUTPUT A
120
100
80
60
40
20
0
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
6
0.001
RECEIVER OUTPUT CURRENT
vs. OUTPUT-HIGH VOLTAGE
MAX13442-4E toc04
RECEIVER OUTPUT CURRENT (mA)
40
0.5
0.01
60
80 100 120
TEMPERATURE (°C)
RECEIVER OUTPUT CURRENT
vs. OUTPUT-LOW VOLTAGE
1.0
0.1
0.000001
-40 -25 -10 5 20 35 50 65 80 95 110 125
4.0
MAX13442E
DI = DE = GND
RE = VCC
1
MAX13442E/MAX13444E
0
0
MAX13442-4E toc03
DRIVER AND RECEIVER
ENABLED
20
10
MAX13442-4E toc07
3
24
MAX13442-4E toc02
DRIVER AND RECEIVER
ENABLED
SUPPLY CURRENT (mA)
5
MAX13442-4E toc01
6
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT (μA)
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT (mA)
MAX13442E/MAX13443E/MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
10
20
30
40
50
60
70
DIFFERENTIAL OUTPUT VOLTAGE (V)
_______________________________________________________________________________________
80
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
80
MAX13442E
DI = GND, DE = VCC,
VOLTAGE APPLIED
TO OUTPUT B
70
60
3.5
50
40
30
20
10
2.0
RL = 54Ω
1.5
1.0
0.5
-65
-50
-35
-20
-40 -25 -10 5 20 35 50 65 80 95 110 125
-5
TEMPERATURE (°C)
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
A, B CURRENT vs. A, B
VOLTAGE (TO GROUND)
MAX13442-4E toc10
RL = 100Ω
A, B CURRENT (μA)
2.5
RL = 54Ω
1.5
1.0
0.5
MAX13443E
0
3200
2800
2400
2000
1600
1200
800
DRIVER DISABLED,
RECEIVER ENABLED
400
0
-400
-800
-1200
-1600
-2000
NO LOAD
RL = 54Ω
MAX13442E
-80 -60
-40 -25 -10 5 20 35 50 65 80 95 110 125
MAX13442-4E toc11
DIFFERENTIAL OUTPUT VOLTAGE (V)
3.5
-40
-20
0
20
40
60
80
A, B VOLTAGE (V)
TEMPERATURE (°C)
2000
1600
MAX13442-4E toc12
A, B CURRENT vs. A, B VOLTAGE
(TO GROUND)
DRIVER DISABLED,
RECEIVER ENABLED
1200
A, B CURRENT (μA)
DIFFERENTIAL OUTPUT VOLTAGE (V)
RL = 100Ω
2.5
MAX13442E
-80
2.0
3.0
0
0
3.0
MAX13442-4E toc09
RL = 54Ω
DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER OUTPUT CURRENT (mA)
90
MAX13442-4E toc08
100
800
400
0
NO LOAD
-400
-800
RL = 54Ω
-1200
-1600
MAX13443E
-2000
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60
A, B VOLTAGE (V)
_______________________________________________________________________________________
7
MAX13442E/MAX13443E/MAX13444E
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
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
DI
A
RL
2
S1
DI
0V
tPLHA
OUT
D
GENERATOR
(NOTE 5)
1.5V
1.5V
tPHLA
VOH
B
50Ω
CL = 50pF
(NOTE 6)
VCC
VOM =
VOM
A
VOM
VOL
tPHLB
VOH + VOL
≈ 1.5V
2
tPLHB
VOH
B
VOM
VOM
VOL
Figure 3. Driver Propagation Times
3V
A
DI
D
GENERATOR
(NOTE 5)
0V
RL
B
1.5V
1.5V
DI
CL
OUT
tDPHL
tDPLH
≈ 2.0V
50Ω
90%
VCC
CL
(A–B)
50%
10%
90%
50%
10%
CL = 50pF (NOTE 6)
tLH
Figure 4. Driver Differential Output Delay and Transition Times
8
_______________________________________________________________________________________
tHL
≈ -2.0V
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
A
DI
0 OR 3V
3V
S1
A, B
D
DE
DE
GENERATOR
(NOTE 5)
RL = 500Ω
CL = 50pF
(NOTE 6)
1.5V
1.5V
tPDZH
B
0V
tPDHS
tPDHZ
50Ω
0.25V
A, B
VOM =
VOH
VOM
VOH + VOL
≈ 1.5V
2
0V
Figure 5. Driver Enable and Disable Times
VCC
3V
A
DI
0 OR 3V
RL = 500Ω
S1
A, B
D
1.5V
1.5V
tPDZL
DE
0V
tPDLS
tPDLZ
B
DE
GENERATOR
(NOTE 5)
CL = 50pF
(NOTE 6)
VCC
A, B
VOM
50Ω
0.25V
VOL
Figure 6. Driver Enable and Disable Times
2.0V
A
GENERATOR
(NOTE 5)
VID
50Ω
R
B
RO
(A–B)
1.0V
1.0V
CL = 20pF
(NOTE 6)
0V
tRPLH
tRPHL
VCC
1.0V
RO
0V
VOM
VOM
0V
Figure 7. Receiver Propagation Delay
_______________________________________________________________________________________
9
MAX13442E/MAX13443E/MAX13444E
Test Circuits and Waveforms (continued)
MAX13442E/MAX13443E/MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Test Circuits and Waveforms (continued)
S1
S3
+1.5V
A
VID
-1.5V
R
RO
VCC
1kΩ
S2
B
CL = 20pF
(NOTE 6)
GENERATOR
(NOTE 5)
50Ω
3V
RE
1.5V
0V
tRPZH
tRPSH
tRPWAKE
RO
3V
S1 OPEN
S2 CLOSED
VS3 = 1.5V
RE
1.5V
0V
tRPZL
tRPSL
VOH
VCC
RO
1.5V
1.5V
0V
VOL
3V
RE
S1 CLOSED
S2 OPEN
VS3 = -1.5V
1.5V
0V
3V
S1 OPEN
S2 CLOSED
VS3 = 1.5V
RE
1.5V
0V
S1 CLOSED
S2 OPEN
VS3 = -1.5V
tRPHZ
RO
0.5V
tRPLZ
VOH
RO
VCC
0.5V
0V
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.
10
______________________________________________________________________________________
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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.
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.
MAX13442E
MAX13443E
MAX13444E
1
4
—
DI
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
Ground
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.
______________________________________________________________________________________
11
MAX13442E/MAX13443E/MAX13444E
Pin Description
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
OUTPUTS
INPUTS
OUTPUTS
RE
DE
DI
A
B
RE
DE
(VA - VB)
RO
0
0
X
High-Z
High-Z
0
X
-0.05V
1
0
1
0
0
1
0
X
-0.2V
0
0
1
1
1
0
0
X
Open/shorted
1
1
0
X
Shutdown
Shutdown
1
1
X
High-Z
1
1
0
0
1
1
0
X
Shutdown
1
1
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.
12
______________________________________________________________________________________
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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,
logic-level output (RO). Deasserting the receiver enable
places the receiver inputs (A and B) into a high-impedance state (see Tables 1–4).
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 dri-
ver 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.
______________________________________________________________________________________
13
MAX13442E/MAX13443E/MAX13444E
Detailed Description
MAX13442E/MAX13443E/MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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 undergoes 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.
RC
1MΩ
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 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
VCC
CHARGE-CURRENTLIMIT RESISTOR
DISCHARGE
RESISTANCE
15μs
TIMER
HIGHVOLTAGE
DC
SOURCE
Cs
100pF
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
TIMER
Figure 9a. Human Body ESD Test Model
DE
(HOT SWAP)
IP 100%
90%
Ir
5.6kΩ
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
100μA
M1
2mA
M2
AMPERES
36.8%
10%
0
Figure 10. Simplified Structure of the Driver Enable Pin (DE)
0
tRL
TIME
tDL
CURRENT WAVEFORM
Figure 9b. Human Body Model Current Waveform
14
______________________________________________________________________________________
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
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
In general, a transmitter’s rise time relates directly to
the length of an unterminated stub, which 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
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
0
500kHz/div
5.00MHz
Figure 12. Driver Output Waveform and FFT Plot of the
MAX13442E Transmitting a 125kHz Signal
______________________________________________________________________________________
15
MAX13442E/MAX13443E/MAX13444E
Applications Information
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 dominantmode 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
R
R
D
D
MAX13442E
MAX13443E
DI
DE
RO RE
DI
DE
RO RE
Figure 13. MAX13442E/MAX13443E Typical RS-485 Network
16
RO
RE
RE
______________________________________________________________________________________
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
PROCESS: BiCMOS
DE
TX
D
TXD
B
C1
2.2nF
A
J1708 BUS
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 SO
S8+4
21-0041
90-0096
R4
47Ω
R2
4.7kΩ
R
RO
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.
C2
2.2nF
MAX13444E
RX
Package Information
R1
4.7kΩ
R3
47Ω
VCC
RE
Figure 14. J1708 Application Circuit (See Tables 2 and 4)
Pin Configurations and Typical Operating Circuits (continued)
DE
+
+
RO
1
R
8
VCC
RO
1
RE 2
7
B
RE 2
DE
6
A
DE
TXD
3
4
D
5
SO
GND
8 VCC
R
D
7 B
6
3
TXD 4
MAX13444E
A
5 GND
D
SO
TXD
B
RT
RT
A
RO
R
RE
______________________________________________________________________________________
17
MAX13442E/MAX13443E/MAX13444E
Chip Information
MAX13442E/MAX13443E/MAX13444E
±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
Revision History
REVISION
NUMBER
REVISION
DATE
0
10/05
1
3/06
2
11/10
3
3/11
DESCRIPTION
Initial release
PAGES
CHANGED
—
Corrected the part numbers in the conditions for VOC in the DC Electrical
Characteristics table; corrected the A, B current units from mA to μA for the A, B
Current vs. A, B Voltage (to Ground) graphs in the Typical Operating Characteristics
section
Added lead(Pb)-free parts to the Ordering Information table; added the soldering
temperature to the Absolute Maximum Ratings section; updated Table 2 outputs
Added an automotive qualified part to the Ordering Information; added the Package
Thermal Characteristics section
2, 7
1, 2, 12
1, 2
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2011 Maxim Integrated Products
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