MAXIM MAX3440EASA+

19-2666; Rev 2; 11/10
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
Features
♦ ±15kV ESD Protection
The MAX3440E–MAX3444E fault-protected RS-485 and
J1708 transceivers feature ±60V protection from signal
faults on communication bus lines. 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 at data rates of up to 10Mbps. 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 MAX3440E–MAX3444E are available in 8-pin SO
and PDIP packages and are specified over industrial
and automotive temperature ranges.
♦ ±60V Fault Protection
♦ Guaranteed 10Mbps Data Rate
(MAX3441E/MAX3443E)
♦ Hot Swappable for Telecom Applications
♦ True Fail-Safe Receiver Inputs
♦ Enhanced Slew-Rate-Limiting Facilitates
Error-Free Data Transmission
(MAX3440E/MAX3442E/MAX3444E)
♦ Allow Up to 128 Transceivers on the Bus
♦ -7V to +12V Common-Mode Input Range
♦ Automotive Temperature Range (-40°C to +125°C)
♦ Industry-Standard Pinout
Ordering Information
Applications
RS-422/RS-485 Communications
Truck and Trailer Applications
Industrial Networks
Telecommunications Systems
Automotive Applications
HVAC Controls
PART
TEMP RANGE
PIN-PACKAGE
MAX3440EESA+
-40°C to +85°C
8 SO
MAX3440EEPA+
-40°C to +85°C
MAX3440EASA+
-40°C to +125°C
8 SO
MAX3440EAPA+
-40°C to +125°C
8 PDIP
8 PDIP
+Denotes a lead(Pb)-free/RoHS-compliant package.
Ordering Information continued at end of data sheet.
Selector Guide
DATA RATE
(Mbps)
LOW-POWER
SHUTDOWN
RECEIVER/DRIVER
ENABLE
TRANSCEIVERS
ON BUS
PART
TYPE
HOT SWAP
MAX3440E
RS-485
0.25
No
Yes
128
Yes
MAX3441E
RS-485
2.5 to 10
No
Yes
128
Yes
MAX3442E
RS-485
0.25
Yes
Yes
128
Yes
MAX3443E
RS-485
2.5 to 10
Yes
Yes
128
Yes
MAX3444E
J1708
0.25
Yes
Yes
128
Yes (only RE)
Pin Configurations and Typical Operating Circuits
TOP VIEW
DE/RE
+
+
FAULT 1
RO 2
R
DE/RE 3
DI
4
D
DIP/SO
8
VCC
7
B
6
A
5
GND
FAULT 1
RO 2
DE/RE
R
3
DI 4
D
8 VCC
7 B
Rt
6
A
5 GND
MAX3440E
MAX3441E
DIP/SO
D
DI
B
Rt
A
RO
R
FAULT
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
MAX3440E–MAX3444E
General Description
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
ABSOLUTE MAXIMUM RATINGS
Voltages Referenced to GND
VCC ........................................................................................+7V
FAULT, DE/RE, RE, DE, DE, DI, TXD..........-0.3V to (VCC + 0.3V)
A, B (Note 1) ........................................................................±60V
RO ..............................................................-0.3V to (VCC + 0.3V)
Short-Circuit Duration (RO, A, B) ...............................Continuous
Continuous Power Dissipation (TA = +70°C)
SO (derate 5.9mW/°C above +70°C) ...........................471mW
PDIP (derate 9.09mW/°C above +70°C) ......................727mW
Operating Temperature Ranges
MAX344_EE_ _ ...............................................-40°C to +85°C
MAX344_EA_ _ .............................................-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: A, B must be terminated with 54Ω or 100Ω to guarantee ±60V fault protection.
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.
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 2)
Figure 1, RL = 100 or 54
VCC / 2
Figure 1, RL = 100 or 54 (Note 2)
V
0.2
V
3
V
0.2
V
0.8
V
±2
μA
DRIVER LOGIC
Driver Input High Voltage
VDIH
Driver Input Low Voltage
VDIL
Driver Input Current
IDIN
Driver Short-Circuit Output Current
(Note 3)
I OSD
Driver Short-Circuit Foldback
Output Current
I OSDF
2
V
0V VOUT +12V
+350
-7V VOUT VCC
-350
(VCC - 1V) VOUT +12V (Note 3)
+25
-7V VOUT +1V (Note 3)
-25
mA
mA
RECEIVER
Input Current
IA,B
A, B
VCC = GND, VA, B = 12V
250
VA, B = -7V
-150
VA, B = ±60V
Receiver Differential Threshold
Voltage
Receiver Input Hysteresis
2
VTH
VTH
-7V VCM +12V
-200
25
_______________________________________________________________________________________
μA
±6
mA
-50
mV
mV
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
MAX3440E–MAX3444E
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 LOGIC
Output High Voltage
VOH
Figure 2, I OH = -1.6mA
Output Low Voltage
VOL
Figure 2, I OL = 1mA
VCC - 0.6
0.4
V
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, DE/RE
48
k
±95
mA
CONTROL
Control Input High Voltage
Input Current Latch During First
Rising Edge
I IN
2
DE, DE/RE, RE
V
90
μA
SUPPLY CURRENT
Normal Operation
IQ
Supply Current in Shutdown Mode
I SHDN
No load,
DI = VCC
or GND
MAX3440E (DE/RE = VCC),
MAX3442E (DE = VCC,
RE = GND),
MAX3444E (DE = RE = GND)
30
MAX3441E (DE/RE = VCC),
MAX3443E (DE = VCC,
RE = GND)
10
mA
DE = GND, RE = VCC (MAX3442E/
MAX3443E)
20
DE = GND, RE = VCC, TA = +25°C
(MAX3442E/MAX3443E)
10
DE = RE = VCC (MAX3444E)
100
DE = RE = VCC, TA = +25°C (MAX3444E)
Supply Current with Output Shorted
to ±60V
I SHRT
μA
10
DE = GND, RE = GND, no load
output in three-state (MAX3443E)
±15
mA
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
Overvoltage Protection
ESD Protection
CONDITIONS
MIN
A, B; RSOURCE = 0, RL = 54
A, B
Human Body Model
±60
TYP
MAX
UNITS
V
±15
kV
FAULT DETECTION
Receiver Differential Threshold
FDIPH
VCM = 0V, high limit
270
450
mV
Receiver Differential Threshold
FDIPL
VCM = 0V, low limit
-450
-270
mV
Fault-Detection Common-Mode
Input Voltage Positive
Fault-Detection Common-Mode
Input Voltage Negative
12
V
-7
V
_______________________________________________________________________________________
3
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
SWITCHING CHARACTERISTICS (MAX3440E/MAX3442E/MAX3444E)
(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
MAX3440E/MAX3442E,
Figure 3, RL = 54, CL = 50pF
Driver Propagation Delay
t PLHA,
t PLHB
Driver Differential Propagation Delay
tDPLH,
tDPHL
Figure 4, RL = 54, CL = 50pF
Driver Differential Output
Transition Time
tLH,tHL
Figure 4, RL = 54, CL = 50pF
MAX
UNITS
2000
ns
2000
ns
2000
ns
MAX3444E, RDIFF = 60, CDIFF = 100pF
200
Driver Output Skew
tSKEWAB,
tSKEWBA
RL = 54, CL = 50pF,
t SKEWAB = |t PLHA - tPHLB|,
t SKEWBA = |t PLHB - tPHLA|
350
ns
Differential Driver Output Skew
tDSKEW
RL = 54, CL = 50pF,
tDSKEW = |tDPLH - tDPHL |
200
ns
Maximum Data Rate
fMAX
250
kbps
Driver Enable Time to Output High
tPDZH
Figure 5, RL = 500, CL = 50pF
2000
ns
Driver Disable Time from Output High
tPDHZ
Figure 5, RL = 500, CL = 50pF
2000
ns
Driver Enable Time from Shutdown to
Output High
t PDHS
Figure 5, RL = 500, CL = 50pF
(MAX3442E/MAX3444E)
4.2
μs
Driver Enable Time to Output Low
tPDZL
Figure 6, RL = 500, CL = 50pF
2000
ns
Driver Disable Time from Output Low
t PDLZ
Figure 6, RL = 500, CL = 50pF
2000
ns
Driver Enable Time from Shutdown to
Output Low
t PDLS
Figure 6, RL = 500, CL = 50pF
(MAX3442E/MAX3444E)
4.2
μs
Driver Time to Shutdown
tSHDN
RL = 500, CL = 50pF (MAX3442E/MAX3444E)
800
ns
Receiver Propagation Delay
tRPLH,
tRPHL
Figure 7, CL = 20pF, VID = 2V, VCM = 0V
2000
ns
Receiver Output Skew
tRSKEW
Receiver Enable Time to Output High
tRPZH
CL = 20pF, tRSKEW = |tRPLH - tRPHL|
Figure 8, RL = 1k, CL = 20pF
Receiver Disable Time from Output
High
tRPHZ
Figure 8, RL = 1k, CL = 20pF
2000
ns
Receiver Wake Time from Shutdown
tRPWAKE
Figure 8, RL = 1k, CL = 20pF
(MAX3442E/MAX3444E)
4.2
μs
Receiver Enable Time to Output Low
tRPZL
Figure 8, RL = 1k, CL = 20pF
2000
ns
Receiver Disable Time from Output Low
tRPLZ
Figure 8, RL = 1k, CL = 20pF
2000
ns
Receiver Time to Shutdown
t SHDN
RL = 500, CL= 50pF
(MAX3442E/MAX3444E)
800
ns
4
_______________________________________________________________________________________
200
ns
2000
ns
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, 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
Figure 3, RL = 27, CL = 50pF
60
ns
tDPLH,
tDPHL
Figure 4, RL = 54, CL = 50pF
60
ns
tLH,tHL
Figure 4, RL = 54, CL = 50pF
25
ns
10
ns
10
ns
Driver Propagation Delay
t PLHA,
t PLHB
Driver Differential Propagation Delay
Driver Differential Output
Transition Time
CONDITIONS
MIN
RL = 54, CL = 50pF,
tSKEWAB,
t SKEWAB = |t PLHA - tPHLB|,
tSKEWBA
t SKEWBA = |t PLHB - tPHLA|
Driver Output Skew
Differential Driver Output Skew
tDSKEW
RL = 54, CL = 50pF,
tDSKEW = |tDPLH - tDPHL |
TYP
Maximum Data Rate
fMAX
Driver Enable Time to Output High
tPDZH
Figure 5, RL = 500, CL = 50pF
10
1200
Mbps
ns
Driver Disable Time from Output High
tPDHZ
Figure 5, RL = 500, CL = 50pF
1200
ns
Driver Enable Time from Shutdown to
Output High
t PDHS
Figure 5, RL = 500, CL = 50pF (MAX3443E)
4.2
μs
Driver Enable Time to Output Low
tPDZL
Figure 6, RL = 500, CL = 50pF
1200
ns
Driver Disable Time from Output Low
t PDLZ
Figure 6, RL = 500, CL = 50pF
1200
ns
Driver Enable Time from Shutdown to
Output Low
t PDLS
Figure 6, RL = 500, CL = 50pF (MAX3443E)
4.2
μs
Driver Time to Shutdown
tSHDN
Figure 6, RL = 500, CL = 50pF (MAX3443E)
800
ns
Receiver Propagation Delay
tRPLH,
tRPHL
Figure 7, CL = 20pF, VID = 2V, VCM = 0V
85
ns
Receiver Output Skew
tRSKEW
CL = 20pF, tRSKEW = |tRPLH - tRPHL|
15
ns
Receiver Enable Time to Output High
tRPZH
Figure 8, RL = 1k, CL = 20pF
400
ns
Receiver Disable Time from Output
High
tRPHZ
Figure 8, RL = 1k, CL = 20pF
400
ns
Receiver Wake Time from Shutdown
tRPWAKE
Figure 8, RL = 1k, CL= 20pF (MAX3443E)
4.2
μs
Figure 8, RL = 1k, CL = 20pF
400
ns
Receiver Enable Wake Time from
Shutdown
tRPSH
Receiver Disable Time from Output Low
tRPLZ
Figure 8, RL = 1k, CL= 20pF
400
ns
Receiver Time to Shutdown
t SHDN
RL = 500, CL= 50pF (MAX3443E)
800
ns
Note 2: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes state.
Note 3: 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
MAX3440E–MAX3444E
SWITCHING CHARACTERISTICS (MAX3441E/MAX3443E)
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
4
DRIVER DISABLED,
RECEIVER ENABLED
3
20
2
1
DRIVER AND RECEIVER
ENABLED
16
12
DRIVER DISABLED,
RECEIVER ENABLED
8
0.1
MAX3440E/MAX3442E/MAX3444E
0
MAX3442E/MAX3443E/MAX3444E
0.01
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
RECEIVER OUTPUT CURRENT
vs. OUTPUT LOW VOLTAGE
RECEIVER OUTPUT CURRENT
vs. OUTPUT HIGH VOLTAGE
RECEIVER OUTPUT VOLTAGE
vs. TEMPERATURE
25
20
15
10
30
25
20
15
10
5
5
0
0
MAX3443E toc06
35
5.0
4.5
RECEIVER OUTPUT VOLTAGE (V)
30
MAX3443E toc05
35
40
RECEIVER OUTPUT CURRENT (mA)
MAX3443E toc04
40
4.0
VOH, IOUT = +10mA
3.5
3.0
2.5
2.0
1.5
VOL, IOUT = -10mA
1.0
0.5
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
OUTPUT LOW VOLTAGE (V)
OUTPUT HIGH VOLTAGE (V)
TEMPERATURE (°C)
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
A, B CURRENT
vs. A, B VOLTAGE (TO GROUND)
60
50
40
30
20
10
RL = 100Ω
2.5
2.0
RL = 54Ω
1.5
1.0
0.5
0.5
1.0
1.5
2.0
2.5
3.0
3.5
DIFFERENTIAL OUTPUT VOLTAGE (VA - VB) (V)
1200
RL = 54Ω
800
400
0
-400
-800
-1600
DRIVER DISABLED,
RECEIVER ENABLED
-2000
0
0
1600
-1200
MAX3441E/MAX3443E
0
MAX3443E toc09
3.0
2000
A, B CURRENT (μA)
70
3.5
MAX3443E toc08
MAX3443E toc07
80
DIFFERENTIAL OUTPUT VOLTAGE (V)
RECEIVER OUTPUT CURRENT (mA)
1
4
MAX3441E/MAX3443E
6
10
MAX3443E toc03
24
SUPPLY CURRENT (μA)
DRIVER AND RECEIVER
ENABLED
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
MAX3440E toc01
6
5
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
MAX3440E toc02
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
DRIVER OUTPUT CURRENT (mA)
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
-40 -25 -10 5 20 35 50 65 80 95 110 125
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60
TEMPERATURE (°C)
A, B VOLTAGE (V)
_______________________________________________________________________________________
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
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
0
tPLHA
OUT
D
GENERATOR
(NOTE 4)
1.5V
1.5V
tPHLA
VOH
B
50Ω
CL = 50pF
(NOTE 5)
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 4)
0
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 5)
tLH
≈ -2.0V
tHL
Figure 4. Driver Differential Output Delay and Transition Times
_______________________________________________________________________________________
7
MAX3440E–MAX3444E
Test Circuits and Waveforms
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
Test Circuits and Waveforms (continued)
A
DI
0 OR 3V
3V
S1
A, B
D
DE
DE
GENERATOR
(NOTE 4)
RL = 500Ω
CL = 50pF
(NOTE 5)
1.5V
1.5V
tPDZH
B
0
tPDHS
tPDHZ
50Ω
0.25V
A, B
VOM =
VOH
VOM
VOH + VOL
≈ 1.5V
2
0
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
0
tPDLS
tPDLZ
B
DE
GENERATOR
(NOTE 4)
CL = 50pF
(NOTE 5)
VCC
A, B
VOM
50Ω
0.25V
VOL
Figure 6. Driver Enable and Disable Times
2.0V
A
GENERATOR
(NOTE 4)
VID
50Ω
R
B
RO
(A–B)
1.0V
1.0V
CL = 20pF
(NOTE 5)
0
tRPLH
tRPHL
VCC
1.0V
RO
VOM
VOM
0
Figure 7. Receiver Propagation Delay
8
_______________________________________________________________________________________
0
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
S1
S3
1.5V
A
-1.5V
VID
R
RO
VCC
1kΩ
S2
B
CL = 20pF
(NOTE 5)
GENERATOR
(NOTE 4)
50Ω
3V
RE
1.5V
0
tRPZH
tRPSH
tRPWAKE
RO
3V
S1 OPEN
S2 CLOSED
VS3 = 1.5V
RE
1.5V
0
tRPZL
tRPSL
VOH
VCC
RO
1.5V
1.5V
0
VOL
3V
RE
S1 CLOSED
S2 OPEN
VS3 = -1.5V
1.5V
0
3V
S1 OPEN
S2 CLOSED
VS3 = 1.5V
RE
1.5V
0
S1 CLOSED
S2 OPEN
VS3 = -1.5V
tRPHZ
RO
tRPLZ
VOH
0.5V
RO
0
VCC
0.5V
VOL
Figure 8. Receiver Enable and Disable Times
Note 4: The input pulse is supplied by a generator with the following characteristics: f = 5MHz, 50% duty cycle; tr ≤ 6ns; Z0 = 50Ω.
Note 5: CL includes probe and stray capacitance.
_______________________________________________________________________________________
9
MAX3440E–MAX3444E
Test Circuits and Waveforms (continued)
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
MAX3440E–MAX3444E
Pin Description
PIN
MAX3440E
MAX3441E
10
MAX3442E
MAX3443E
MAX3444E
NAME
FUNCTION
Fault output. 1 = fault; 0 = normal operation
A or B under the following conditions:
• A-B differential <200mV
• A shorted to B
• A shorted to a voltage within the common-mode range
(detected only when the driver is enabled)
• B shorted to a voltage within the common-mode range
(detected only when the driver is enabled)
• A or B outside the common-mode range
1
—
—
FAULT
2
1
1
RO
Receiver Output. If receiver enabled and (A-B) -50mV,
RO = high; if (A-B) -200mV, RO = low.
—
2
2
RE
Receiver Output Enable. Pull RE low to enable RO.
—
—
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.
3
—
—
DE/RE
Driver/Receiver Output Enable. Pull DE/RE low to threestate the driver output and enable RO. Force DE/RE high
to enable driver output and three-state 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
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.
—
—
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.
5
5
5
GND
Ground
6
6
6
A
Noninverting Receiver Input/Driver Output
7
7
7
B
Inverting Receiver Input/Driver Output
8
8
8
VCC
Positive Supply, VCC = +4.75V to +5.25V
______________________________________________________________________________________
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
Table 1. MAX3440E/MAX3441E Fault Table
INPUTS
A-B
VID DIFFERENTIAL
INPUT VOLTAGE
OUTPUTS
COMMON-MODE
VOLTAGE
RO
FAULT
CONDITIONED
BY DELAY
FAULT CONDITION
≥0.45V
1
0
Normal operation
<0.45V and ≥0.27V
1
Indeterminate
Indeterminate
<0.27V and ≥-0.05V
1
1
Low-input differential voltage
≤-0.05V and ≥-0.2V
Indeterminate
(Note 1)
1
Low-input differential voltage
Low-input differential voltage
≤12V and ≥-7V
≤-0.2V and >-0.27V
0
1
≤-0.27V and >-0.45V
0
Indeterminate
≤-0.45V
0
0
Indeterminate
1
X
<-7V or >+12V
Indeterminate
Outside common-mode voltage range
X = Don’t care.
Note 1: Receiver output may oscillate with this differential input condition.
Table 3. MAX3442E/MAX3443E
(RS-485/RS-422)
Table 2. MAX3440E/MAX3441E
(RS-485/RS-422)
TRANSMITTING
INPUTS
TRANSMITTING
INPUTS
DE/RE
A
DE
DI
A
B
0
0
X
High-Z
High-Z
B
0
1
0
0
1
1
1
1
0
OUTPUTS
DI
OUTPUTS
RE
0
X
High-Z
High-Z
0
1
0
0
1
1
0
X
Shutdown
Shutdown
1
1
1
0
1
1
0
0
1
1
1
1
1
0
X = Don’t care.
X = Don’t care.
Table 4. MAX3444E (J1708) Application
Table 5. MAX3440E/MAX3441E
(RS-485/RS-422)
TRANSMITTING
INPUTS
OUTPUTS
RECEIVING
CONDITIONS
INPUTS
OUTPUTS
TXD
DE
A
B
—
DE/RE
(A - B)
RO
0
1
High-Z
High-Z
—
0
≥-0.05V
1
1
1
High-Z
High-Z
—
0
≤-0.2V
0
0
0
0
1
Dominant state
0
Open/shorted
1
1
0
High-Z
High-Z
Recessive state
1
X
High-Z
X = Don’t care.
______________________________________________________________________________________
11
MAX3440E–MAX3444E
Function Tables
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
Function Tables (continued)
Table 6. MAX3442E/MAX3443E
(RS-485/RS-422)
Table 7. MAX3444E (RS-485/RS-422)
RECEIVING
RECEIVING
INPUTS
INPUTS
OUTPUTS
OUTPUTS
RE
DE
(A - B)
RO
RE
DE
(A - B)
RO
0
X
≥-0.05V
1
0
X
≥-0.05V
1
0
X
≤-0.2V
0
0
X
≤-0.2V
0
0
X
Open/shorted
1
0
X
Open/shorted
1
1
1
X
High-Z
1
0
X
High-Z
1
0
X
Shutdown
1
1
X
Shutdown
X = Don’t care.
X = Don’t care.
Detailed Description
The MAX3440E–MAX3444E fault-protected transceivers
for RS-485/RS-422 and J1708 communication contain
one driver and one receiver. These devices feature failsafe 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
MAX3440E/MAX3442E/MAX3444E 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 MAX3441E/
MAX3443E drivers are 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.
Low-Power Shutdown
(MAX3442E/MAX3443E/MAX3444E)
The MAX3442E/MAX3443E/MAX3444E offer a low-power
shutdown mode. Force DE low and RE high to shut down
the MAX3442E/MAX3443E. Force DE and RE high to
shut down the MAX3444E. 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 MAX3442E/MAX3443E enter
shutdown. In shutdown, the devices consume a maximum 20µA supply current.
±60V 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/TIA485 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 outputs/receiver inputs of the
MAX3440E–MAX3444E withstand voltage faults up to
±60V with respect to ground without damage.
Protection is guaranteed regardless whether the device
is active, shut down, or without power.
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 1–7).
12
True Fail-Safe
The MAX3440E–MAX3444E 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-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
ESD Test Conditions
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
RC
1MΩ
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
Cs
100pF
RD
1.5kΩ
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.
IP 100%
90%
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
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.
Ir
AMPERES
DEVICE
UNDER
TEST
36.8%
10%
0
0
Figure 9a. Human Body ESD Test Model
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
tRL
TIME
tDL
CURRENT WAVEFORM
Figure 9b. Human Body Model Current Waveform
______________________________________________________________________________________
13
MAX3440E–MAX3444E
±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
MAX3440E–MAX3444E 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 MAX3440E–MAX3444E 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.
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, 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, DE/RE, 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 MAX3440E–MAX3444E
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
MAX3440E–MAX3443E feature hot-swap input circuitry
on DE, DE/RE, and RE to guard against unwanted driver activation during hot-swap situations. The
MAX3444E 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 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.
__________Applications Information
128 Transceivers on the Bus
The MAX3440E–MAX3444E 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 MAX3440E/MAX3442E/MAX3444E 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 MAX3443E.
High-frequency harmonic components with large amplitudes are evident.
Figure 12 shows the same signal displayed for a
MAX3442E 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.
VCC
15μs
TIMER
TIMER
DE
(HOT SWAP)
5.6kΩ
100μA
M1
2mA
M2
Figure 10. Simplified Structure of the Driver Enable Pin (DE)
14
______________________________________________________________________________________
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
where tRISE is the transmitter’s rise time.
For example, the MAX3442E’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 MAX3440E–MAX3443E transceivers provide bidirectional data communications on multipoint bus transmission lines. Figures 13 and 14 show a typical network
applications 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.
0
500kHz/div
J1708 Applications
The MAX3444E is designed for J1708 applications. To
configure the MAX3444E, 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 15. 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 6MHz 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.
20dB/div
20dB/div
2V/div
2V/div
5.00MHz
Figure 11. Driver Output Waveform and FFT Plot of MAX3443E
Transmitting a 125kHz Signal
0
500kHz/div
5.00MHz
Figure 12. Driver Output Waveform and FFT Plot of MAX3442E
Transmitting a 125kHz Signal
______________________________________________________________________________________
15
MAX3440E–MAX3444E
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)
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
120Ω
120Ω
DE/RE
B
B
DI
D
D
DI
DE/RE
A
RO
FAULT
B
A
B
A
A
RO
R
R
FAULT
R
R
D
D
MAX3440E
MAX3441E
DE/RE RO FAULT
DI
DI
DE/RE
RO FAULT
Figure 13. MAX3440E/MAX3441E Typical RS-485 Network
120Ω
120Ω
DE
B
B
DI
D
D
DI
DE
RO
A
B
A
B
A
A
R
R
R
R
D
D
MAX3442E
MAX3443E
DI
DE
RO RE
DI
DE
RO RE
Figure 14. MAX3442E/MAX3443E Typical RS-485 Network
16
RO
RE
RE
______________________________________________________________________________________
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
DE
Tx
D
TXD
B
PART
TEMP RANGE
PIN-PACKAGE
MAX3441EESA+
-40°C to +85°C
8 SO
R1
4.7kΩ
R3
47Ω
MAX3441EEPA+
-40°C to +85°C
8 PDIP
MAX3441EASA+
-40°C to +125°C
8 SO
MAX3441EAPA+
-40°C to +125°C
8 PDIP
C1
2.2nF
MAX3442EESA+
-40°C to +85°C
C2
2.2nF
MAX3444E
A
Rx
R4
47Ω
R2
4.7kΩ
R
RO
J1708 BUS
RE
VCC
Figure 15. J1708 Application Circuit
8 SO
MAX3442EEPA+
-40°C to +85°C
MAX3442EASA+
-40°C to +125°C
8 SO
8 PDIP
MAX3442EAPA+
-40°C to +125°C
8 PDIP
MAX3443ECSA+
0°C to +70°C
MAX3443ECPA+
0°C to +70°C
MAX3443EESA+
-40°C to +85°C
8 SO
8 PDIP
8 SO
MAX3443EEPA+
-40°C to +85°C
MAX3443EASA+
-40°C to +125°C
8 SO
8 PDIP
MAX3443EAPA+
-40°C to +125°C
8 PDIP
MAX3444EESA+
-40°C to +85°C
8 SO
MAX3444EEPA+
-40°C to +85°C
8 PDIP
MAX3444EASA+
-40°C to +125°C
8 SO
MAX3444EAPA+
-40°C to +125°C
8 PDIP
+Denotes a lead(Pb)-free/RoHS-compliant package.
Pin Configurations and Typical Operating Circuits (continued)
TOP VIEW
DE
+
+
RO
RE
R
1
8
VCC
RO
2
7
B
RE 2
DE 3
6
A
DE
3
5
GND
DI
4
DI
4
D
R
1
D
DIP/SO
8 VCC
7 B
Rt
6
A
5 GND
MAX3442E
MAX3443E
D
DI
B
Rt
A
RO
R
RE
DIP/SO
DE
+
+
R
1
8
VCC
RO
RE 2
7
B
RE 2
DE
3
6
A
DE
TXD
4
5
GND
RO
1
D
DIP/SO
R
3
TXD 4
D
DIP/SO
MAX3444E
8 VCC
7 B
Rt
6
A
5 GND
D
TXD
B
Rt
A
RO
R
RE
______________________________________________________________________________________
17
MAX3440E–MAX3444E
Ordering Information (continued)
MAX3440E–MAX3444E
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
Chip Information
PROCESS: BiCMOS
18
Package Information
For the latest package outline information and land patterns,
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.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 SO
S8+4
21-0041
90-0096
______________________________________________________________________________________
±15kV ESD-Protected, ±60V Fault-Protected,
10Mbps, Fail-Safe RS-485/J1708 Transceivers
REVISION
NUMBER
REVISION
DATE
0
10/02
Initial release
1
12/05
Corrected the supply current units from μA to mA for the Shutdown Supply Current
vs. Temperature graph in the Typical Operating Characteristics section; updated the
outputs in Table 4; updated Figure 15
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 4 outputs
DESCRIPTION
PAGES
CHANGED
—
6, 11, 17
1, 2, 11, 17
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19
© 2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX3440E–MAX3444E
Revision History