19-5254; Rev 2; 2/15
General Description
The MAX13450E/MAX13451E are half-duplex and full-
duplex RS-485/RS-422 transceivers. These devices fea-
ture internal 100I and 120I termination resistors. The
resistor values are pin selectable. A logic supply input
allows interfacing to logic levels down to +1.8V.
The MAX13450E/MAX13451E feature strong drivers
specified to drive low-impedance lines found when a
fully loaded bus, based on today’s 100I characteristic
impedance cable, is doubly terminated. Both devices
allow slew-rate limiting of the driver output to reduce EMI
and reflections for data rates up to 500kbps.
The MAX13451E has a FAULT alarm indication output to
signal to the system that an error condition exists in the
driver. The MAX13451E also features a logic inversion
function. The logic inversion allows phase reversal of the
A-B signals in case these are inadvertently connected
wrongly.
The MAX13450E/MAX13451E have 1/8-unit load receiver
input impedance, allowing up to 256 transceivers on the
bus. All driver outputs are protected to Q30kV ESD using
the Human Body Model (HBM).
The MAX13450E/MAX13451E are available in a 14-pin
TSSOP package and operate over the automotive -40NC
to +125NC temperature range.
Applications
●Industrial Control Systems
●Portable Industrial Equipment
●Motor Control
●Security Networks
●Medical Networks
Benets and Features
●Easy Configuration of RS-422 and RS-485 Networks
Up to 20Mbps (max) Data Rate
• Software/Pin-Selectable100Ω/120ΩTermination
• Integrated, Switchable Resistors Eliminate the
Need for External Resistors or DIP Switches
• DriverDrives100ΩDoubleTerminationand
Supports Cat-5/Cat-6 and 24-AWG Cables
• Pin-Selectable Slew-Rate Limiting Reduces EMI
for Data Rates Up to 500kbps
• 1/8UnitLoadAllowsUpto256TransceiversOn
the Bus
●Designed to Perform in Harsh Environments
• Extended ESD Protection
±30kV Human Body Model
±15kV Air Gap Discharge per IEC 61000-4-2
±7kV Contact Discharge per IEC 61000-4-2
• Inverting of A, B Line Polarity (MAX13451E) Allows
Phase Reversal if Misconnected
• ThermalandOvercurrentProtection
• Driver Fault Indication (MAX13451E)
• Fail-Safe Receivers
• -40°Cto+125°CTemperatureRange
• +4.5V to +5.5V Supply Voltage Range
●Integrated Low-Voltage Logic Interface (Down to 1.8V)
Interfaces with Small-Geometry ASICs and FPGA
Note: All devices are specified over the -40°C to +125°C
operating temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Ordering Information/Selector Guide
Functional Diagram (MAX13451E)
MAX13451E
D
LOGIC-LEVEL
TRANSLATION
LOGIC
SRL
INV
DI
FAULT
DE
TERM
B
A
RE
RO
TERM100
GND
VLVCC
PART HALF/FULL
DUPLEX PIN-PACKAGE
MAX13450EAUD+ Full 14 TSSOP-EP*
MAX13451EAUD+ Half 14 TSSOP-EP*
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
(All voltages referenced to GND.)
VCC, VL ...................................................................-0.3V to +6V
DE, RE, DI, RO, TERM, TERM100, SRL ..... -0.3V to (VL + 0.3V)
INV, FAULT ................................................. -0.3V to (VL + 0.3V)
A, B, Z, Y ..................................................................-8V to +13V
A to B (High-Z State) ......................................................... +14V
B to A (High-Z State) ......................................................... +14V
Short-Circuit Duration (RO, Y, Z) to GND ................ Continuous
Continuous Power Dissipation (TA = +70NC)
TSSOP (derate 25.6mW/NC above +70NC)................2051mW
Operating Temperature Range ....................... -40NC to +125NC
Storage Temperature Range .......................... -65NC to +150NC
Junction Temperature ....................................................+150NC
Lead Temperature (soldering, 10s) ...............................+300NC
Soldering Temperature (reflow) ......................................+260NC
Electrical Characteristics
(VCC = +4.5V to +5.5V, VL = +1.62V to VCC, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V,
VL = +1.8V, and TA = +25NC.) (Note 2)
Absolute Maximum Ratings
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-lay-
er board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Package Thermal Characteristics (Note 1)
TSSOP
Junction-to-Ambient Thermal Resistance (qJA) ..........39°C/W
Junction-to-Case Thermal Resistance (qJC) .................3°C/W
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage VCC 4.5 5.5 V
Logic Supply Voltage VL1.62 1.8 VCC V
Supply Current ICC DE = RE = high, TERM = high, no load 6mA
DE = RE = low, TERM = low, no load 12
Logic Supply Current ILCurrent into VL, no load on RO, device not
switching, DE = RE = high 2FA
Shutdown Current ISHDN
Current into VCC, DE = low, RE = TERM =
high 30 FA
Current into VCC, DE = low, RE = high,
TERM = low 8 mA
DRIVER
Differential Driver Output VOD RDIFF = 100I, Figure 1 (Note 3) 2.0 VCC V
RDIFF = 46I, Figure 1 (Note 3) 1.5 VCC
Change in Magnitude of
Differential Output Voltage DVOD RDIFF = 100I or 46I, Figure 1 (Note 3) 0.2 V
Driver Common-Mode Output
Voltage VOC RDIFF = 100I or 46I, Figure 1 (Note 3) VCC/2 3 V
Change In Magnitude of
Common-Mode Voltage DVOC RDIFF = 100I or 46I, Figure 1 (Note 3) 0.2 V
Driver Short-Circuit Output
Current IOSD 0V P VOUT P +12V +280 mA
-7V P VOUT P 0V -250
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2
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Electrical Characteristics (continued)
(VCC = +4.5V to +5.5V, VL = +1.62V to VCC, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V,
VL = +1.8V, and TA = +25NC.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Driver Short-Circuit Foldback
Output Current IOSDF (VCC - 1V) P VOUT P +12V +15 mA
-7V P VOUT P 0V -15
RECEIVER
Input Current (A and B) IA, B
DE = RE = GND;
TERM = VL; VCC = GND
or 5.5V
VA or VB = +12V 125
FA
VA or VB = -7V -100
Receiver Differential Threshold
Voltage VTH
-7V P VCM P +12V,
DE = RE = GND;
TERM = VL; VCC = GND
VA or VB = +12V -200 -50 mV
Receiver Input Hysteresis DVTH VA + VB = 0V 15 mV
LOGIC INTERFACE
Input High Voltage VIH DI, DE, RE, TERM, SRL, TERM100, INV 2/3 x VLV
Input Low Voltage VIL DI, DE, RE, TERM, SRL, TERM100, INV 1/3 x VLV
Input Current IIN DI, DE, RE, TERM, TERM100, SRL, INV -1 +1 FA
Receiver Output High Voltage VROH IOUT = -1mA VL - 0.6 V
Receiver Output Low Voltage VROL IOUT = +1mA 0.4 V
Three-State Output Current at
Receiver IOZR 0V P VRO P VL-1 +0.01 +1 FA
Receiver Output Short-Circuit
Current IOSR 0V P VRO P VLQ1Q80 mA
Fault Output High Voltage
(MAX13451E) VFAULTH Fault condition, IOUT = -1mA VL - 0.6 V
Fault Output Low Voltage
(MAX13451E) VFAULTL Nonfault condition; IOUT = +1mA 0.4 V
TERMINATION RESISTOR
100I Termination Resistor R100 TERM = low, TERM100 = high 85 100 115 I
120I Termination Resistor R120 TERM = low, TERM100 = low 101 120 139 I
Single-Ended Input Capacitance
vs. GND CIN f = 1MHz (MAX13451E only) 40 pF
ESD PROTECTION
ESD Protection (A, B, Y, Z)
Human Body Model Q30
kVIEC 61000-4-2 Air Gap Discharge Q15
IEC 61000-4-2 Contact Discharge Q7
ESD Protection (All Other Pins) Human Body Model Q2
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3
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Switching Characteristics—SRL = HIGH
(VCC = +4.5V to +5.5V, VL = +1.62V to VCC, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V,
VL = +1.8V and TA = +25NC.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DRIVER
Driver Propagation Delay tDPLH RDIFF = 54I, CL = 50pF, Figures 2 and 3 800 ns
tDPHL 800
Differential Driver Output Skew
|tDPLH - tDPHL|tDSKEW RDIFF = 54I, CL = 50pF, Figure 3 100 ns
Driver Differential Output Rise or
Fall Time
tHL RDIFF = 54I, CL = 50pF, Figures 2 and 3 100 600 ns
tLH 100 600
Maximum Data Rate DRMAX 500 kbps
Driver Enable from Shutdown to
Output High tDZH(SHDN) S2 closed, RL = 500I, CL = 100pF,
Figures 4 and 5 4500 ns
Driver Enable from Shutdown to
Output Low tDZL(SHDN) S1 closed, RL = 500I, CL = 100pF,
Figures 4 and 5 5200 ns
Driver Disable Delay tDLZ, tDHZ Figures 4 and 5 100 ns
Driver Enable Delay tDZL, tDZH Figures 4 and 5 2500 ns
RECEIVER
Receiver Propagation Delay tRPLH CL = 15pF, |VID| R 2.0V; tLH, tHL P 15ns,
Figures 6 and 7
200 ns
tRPHL 200
Receiver Output Skew tRSKEW CL = 15pF, Figures 6 and 7 30 ns
Maximum Data Rate DRMAX 500 kbps
Receiver Enable to Output High tRZH S2 closed, CL = 100pF, RL = 500I,
Figures 8 and 9 50 ns
Receiver Enable to Output Low tRZL S1 closed, CL = 100pF, RL = 500I,
Figures 8 and 9 50 ns
Receiver Disable from High tRHZ Figures 8 and 9 50 ns
Receiver Disable from Low tRLZ Figures 8 and 9 50 ns
Receiver Enable from Shutdown
to Output High tRZH(SHDN) Figures 8 and 9 5000 ns
Receiver Enable from Shutdown
to Output Low tRZL(SHDN) Figures 8 and 9 5000 ns
TERMINATION RESISTOR
Turn-Off Time tRTZ Figure 10 120 Fs
Turn-On Time tRTEN Figure 10 1Fs
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MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Switching Characteristics—SRL = LOW
(VCC = +4.5V to +5.5V, VL = +1.62V to VCC, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V,
VL = +1.8V, and TA = +25NC.) (Note 2)
Note 2: All devices are 100% production tested at TA = +25°C. Limits over temperature are guaranteed by design.
Note 3: Termination resistance is disabled (TERM = high).
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DRIVER
Driver Propagation Delay tDPLH RDIFF = 54I, CL = 50pF, Figures 2 and 3 50 ns
tDPHL 50
Differential Driver Output Skew
|tDPLH - tDPHL|tDSKEW RDIFF = 54I, CL = 50pF, Figure 3 6 ns
Driver Differential Output Rise or
Fall Time tHL, tLH RDIFF = 54I, CL = 50pF, Figures 2 and 3 15 ns
Maximum Data Rate DRMAX 20 Mbps
Driver Enable from Shutdown to
Output High tDZH(SHDN) S2 closed, RL = 500I, CL = 100pF,
Figures 4 and 5 2000 ns
Driver Enable from Shutdown to
Output Low tDZL(SHDN) S1 closed, RL = 500I, CL = 100pF,
Figures 4 and 5 2000 ns
Driver Disable Delay tDLZ, tDHZ Figures 4 and 5 100 ns
Driver Enable Delay tDZL, tDZH Figures 4 and 5 100 ns
RECEIVER
Receiver Propagation Delay tRPLH CL = 15pF, |VID| R 2.0V; tLH, tHL P 15ns,
Figures 6 and 7
50 ns
tRPHL 50
Receiver Output Skew tRSKEW CL = 15pF, Figures 6 and 7 6 ns
Maximum Data Rate DRMAX 20 Mbps
Receiver Enable to Output High tRZH S2 closed, CL = 100pF, RL = 500I,
Figures 8 and 9 50 ns
Receiver Enable to Output Low tRZL S1 closed, CL = 100pF, RL = 500I,
Figures 8 and 9 50 ns
Receiver Disable Time from High tRHZ Figures 8 and 9 50 ns
Receiver Disable Time from Low tRLZ Figures 8 and 9 50 ns
Receiver Enable from Shutdown
to Output High tRZH(SHDN) Figures 8 and 9 2000 ns
Receiver Enable from Shutdown
to Output Low tRZL(SHDN) Figures 8 and 9 2000 ns
TERMINATION RESISTOR
Turn-Off Time tRTZ Figure 10 120 Fs
Turn-On Time tRTEN Figure 10 1Fs
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5
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Typical Operating Characteristics
(VCC = +5V, VL = +1.8V, TA = +25NC, unless otherwise noted.)
DRIVER DIFFERENTIAL OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX13450E/51E toc07
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER DIFFERENTIAL OUTPUT CURRENT (mA)
4321
20
40
60
80
100
0
0 5
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
MAX13450E/51E toc06
TEMPERATURE (°C)
RECEIVER PROPAGATION DELAY (ns)
1109580655035205-10-25
20
40
60
80
100
0
-40 125
INV = HIGH
INV = LOW
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
MAX13450E/51E toc05
TEMPERATURE (°C)
RECEIVER OUTPUT LOW VOLTAGE (V)
1109580655035205-10-25
0.1
0.2
0.3
0.4
0.5
0
-40 125
IOUT = 1mA
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
MAX13450E/51E toc04
TEMPERATURE (°C)
RECEIVER OUTPUT HIGH VOLTAGE (V)
1109580655035205-10-25
1.2
1.4
1.6
1.8
2.0
1.0
-40 125
IOUT = 1mA
RECEIVER OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX13450E/51E toc03
OUTPUT CURRENT (mA)
RECEIVER OUTPUT VOLTAGE (V)
605040302010
1
2
3
4
5
0
0 70
SOURCE
SINK
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX13450E/51E toc02
TEMPERATURE (°C)
SHUTDOWN CURRENT (µA)
1109565 80-10 5 20 35 50-25
1
2
3
4
5
6
7
8
9
10
0
-40 125
SUPPLY CURRENT
vs. DATA RATE
MAX13450E/51E toc01
DATA RATE (Mbps)
SUPPLY CURRENT (mA)
101
10
20
30
40
50
60
70
0
0.1 100
RL = 54Ω
RL = 100Ω
NO LOAD
TRANSMITTER OUTPUT CURRENT
vs. TRANSMITTER OUTPUT LOW VOLTAGE
MAX13450E/51E toc09
TRANSMITTER OUTPUT LOW VOLTAGE (V)
TRANSMITTER OUTPUT CURRENT (mA)
72
20
40
60
80
100
120
140
160
180
200
0
-3 12
TRANSMITTER OUTPUT CURRENT
vs. TRANSMITTER OUTPUT HIGH VOLTAGE
MAX13450E/51E toc08
TRANSMITTER OUTPUT HIGH VOLTAGE (V)
TRANSMITTER OUTPUT CURRENT (mA)
3-2
20
40
60
80
100
120
0
-7
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MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Typical Operating Characteristics (continued)
(VCC = +5V, VL = +1.8V, TA = +25NC, unless otherwise noted.)
100Ω TERMINATION RESISTOR
vs. FREQUENCY
FREQUENCY (MHz)
MAGNITUDE (Ω)
PHASE (DEGREE)
101
20
40
60
80
100
120
140
0
0.1 100
0
-10
-20
-30
MAX13450E/51E toc11
R100 MAGNITUDE
R100 PHASE
120Ω TERMINATION RESISTOR
vs. FREQUENCY
FREQUENCY (MHz)
MAGNITUDE (Ω)
PHASE (DEGREE)
101
20
40
60
80
100
120
140
0
0.1 100
0
-10
-20
-30
MAX13450E/51E toc12
R120 MAGNITUDE
R120 PHASE
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
MAX13450E/51E toc10
TEMPERATURE (°C)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
1109580655035205-10-25
1
2
3
4
5
0
-40 125
RDIFF = 54Ω
TERMINATION RESISTANCE
vs. TEMPERATURE
MAX13450E/51E toc13
TEMPERATURE (°C)
TERMINATION RESISTANCE (Ω)
1109580655035205-10-25
90
100
110
120
130
80
-40 125
120Ω RESISTOR
100Ω RESISTOR
DRIVER PROPAGATION DELAY (250kbps)
(MAX13451E)
MAX13450E/51E toc14
1µs/div
DI
1V/div
A
1V/div
B
1V/div
SRL = HIGH
DE = HIGH
RE = HIGH
DRIVER ENABLE TIME FROM SHUTDOWN
(MAX13451E)
MAX13450E/51E toc15
200ns/div
DE
2V/div
A
2V/div
B
2V/div
SRL = LOW
RE = HIGH
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7
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MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Test Circuits and Waveforms
Figure 1. Driver DC Test Load
Figure 3. Driver Propagation Delays
Figure 2. Driver Timing Test Circuit
VOC
A/Y
B/Z
RDIFF 2
RDIFF
VOD CL
2
A
B
DE
DI
VL
RDIFF CL
VID
VL/2 VL/2
0V
DI
B
A
tDPLH tDPHL
1/2 VO
1/2 VO
VO
10%
90%
10%
90%
0V
VO
-VO
VDD
tDSKEW = |tDPLH - tDPHL|
tHL
tLH
VLf = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns
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MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Test Circuits and Waveforms (continued)
Figure 5. Driver-Enable and Disable-Timing Test Load
Figure 4. Driver Enable and Disable Times
Figure 7. Receiver Propagation Delays
Figure 6. Receiver Propagation Delay Test Circuit
VL/2 VL/2
VCC
VOH
0V
0V
OUTPUT NORMALLY LOW
DE
OUTPUT NORMALLY HIGH
tDZL(SHDN),tDZL
tDZH(SHDN),tDZH
tDLZ
tDHZ
(VCC + VOL)/2
VOH/2
VOL + 0.25V
VOH - 0.25V
A/Y, B/Z
A/Y, B/Z
VOL
VL
OUTPUT
UNDER TEST
500ΩS1
S2
VCC
CL
ATE VID
A
B
RRECEIVER
OUTPUT
VL/2 VL/2
1V
-1V
f = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns
tRPHL tRPLH
VROH
VROL
RO
A
B
tRSKEW = |tRPHL - tRPLH|
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9
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Test Circuits and Waveforms (continued)
Figure 8. Receiver Enable and Disable Times
Figure 9. Receiver Enable and Disable Times
Figure 10. Termination Resistor Turn-On/-Off Times
VL/2 VL/2
RO
0V
0V
OUTPUT NORMALLY LOW
RO
OUTPUT NORMALLY HIGH
tRZH(SHDN), tRZH tRHZ
tRHZ
(VL + VROL)/2
VROH/2 ROH - 0.25V
ROH + 0.25V
DI = 0V
RE
VL
VL
VROH
VROL
tRZL(SHDN), tRZL
RO
500ΩS1
S2
VCC
CL
90%
10%
0V
VAB = VA - VB
RD = R100 OR R200
VL
VL/2
tREN tREN
IA
RECEIVERRO
TERM
B
IA = VAB/RD
A
TERM
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10
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Pin Congurations
Pin Description
+
TOP VIEW
TSSOP
114 GNDVCC
123 ZDI
132 TERM100RE
141 SRLDE
87 ARO
96 BVL
105 YTERM
*EP
MAX13450E
+
TOP VIEW
TSSOP
114 GNDVCC
123 BDI
132 TERM100RE
141 SRLDE
87 INVRO
96 FAULTVL
105 ATERM
*EP
*CONNECT EP TO GND
MAX13451E
PIN NAME FUNCTION
MAX13450E MAX13451E
1 1 DE Driver-Output Enable. Drive DE low to put the driver output in three-state. Drive DE
high to enable the driver. DE is referenced to VL.
2 2 RE
Receiver-Output Enable. Drive RE low to enable the RO. Drive RE high to disable
the RO output and put the RO output in a high-impedance state. RE is referenced
to VL.
3 3 DI
Driver Input. Drive DI low to force the noninverting output low and the inverting
output high. Drive DI high to force the noninverting output high and inverting out-
put low. DI is referenced to VL.
4 4 VCC Power-Supply Voltage. Bypass VCC to GND with a 0.1FF ceramic capacitor
placed as close as possible to the device.
5 5 TERM Active-Low Termination Resistor Enable. Drive TERM low to enable the internal ter-
mination resistor. TERM is referenced to VL.
6 6 VLLogic Supply Voltage. Bypass VL to GND with a 0.1FF ceramic capacitor placed
as close as possible to the device.
7 — RO Receiver Output. When receiver is enabled and VA - VB R -50mV, RO is high. If
VA - VB P -200mV, RO is low. RO is referenced to VL.
— 7 RO
Receiver Output. When INV is low, receiver is enabled and VA - VB R -50mV, RO is
high. If VA - VB P -200mV, RO is low. When INV is high, receiver is enabled and
VA - VB R -50mV, RO is low. If VA - VB P -200mV, RO is high. RO is referenced to VL.
8 — A Noninverting Receiver Input
— 10 A If INV is low, A is a noninverting receiver input and a noninverting driver output. If
INV is high, A is an inverting receiver input and an inverting driver output.
9 — B Inverting Receiver Input
— 12 B If INV is low, B is an inverting receiver input and an inverting driver output. If INV
is high, B is a noninverting receiver input and a noninverting driver output.
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11
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Pin Description (continued)
Function Tables
Table 1. Termination Resistor Control
(MAX13450E/MAX13451E)
Table 4. Function Table for Receiver
(MAX13450E)
Table 5. INV Input Function Table for
Transmitter (MAX13451E)
Table 2. Shutdown Control (MAX13450E/
MAX13451E)
Table 3. Function Table for Transmitter
(MAX13450E)
PIN NAME FUNCTION
MAX13450E MAX13451E
10 — Y Noninverting Driver Output
11 11 GND Ground
12 — Z Inverting Driver Output
13 13 TERM100
Termination Resistor Value Selection Input. Drive TERM100 low to select a 120I
termination and high to select a 100I termination. The TERM100 input is refer-
enced to VL.
14 14 SRL Slew-Rate Limiting-Enable Input. Drive SRL high to enable slew-rate limiting and
low to disable slew-rate limiting. The SRL input is referenced to VL.
— 8 INV Inversion Input. Drive INV high to internally swap RO logic level with respect to A
and B signals.
— 9 FAULT Fault Flag Output. FAULT asserts high in overcurrent conditions or if A/B are forced
below GND or above VCC when the driver is enabled. FAULT is referenced to VL.
— — EP Exposed Pad. Connect EP to GND. Do not use EP as the only GND connection.
TERM DE RE TERMINATION RESISTOR
Low X X Activated
High X X Not activated
DE RE TERM STATE
Low High High Shutdown
INPUT OUTPUT
DE DI Y Z
Low X High-Z High-Z
High Low Low High
High High Low
INPUT OUTPUT
RE A-B RO
High X High-Z
Low R -50mV or Open High
P -200mV Low
INPUT OUTPUT
DE INV DI A B
Low X X High-Z High-Z
High
Low Low Low High
High High Low
High Low High Low
High Low High
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12
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Detailed Description
The MAX13450E is a full-duplex, RS-485/RS-422-
compatible transceiver and the MAX13451E is a half-
duplex, RS-485/RS-422-compatible transceiver. Both
devices have an internal 100I/120I termination resistor.
The MAX13450E/MAX13451E have a VL supply voltage
input to support down to a +1.8V voltage logic interface.
The MAX13450E/MAX13451E feature a 1/8-unit load
receiver input impedance, allowing up to 256 transceiv-
ers on the bus. All line interface pins are protected to
Q30kV ESD based on the HBM. These devices also
include fail-safe circuitry, guaranteeing a defined logic-
level receiver output when the receiver inputs are open
or shorted.
The MAX13450E/MAX13451E allow slew-rate-limited
driver outputs for lower data rates below 500kbps. The
SRL reduces the slew rate, which reduces EMI emissions
and reflections caused by improperly terminated cables.
The MAX13451E has a FAULT output that indicates a
fault condition on the driver. The MAX13451E also has an
INV input that inverts the phase of A and B pins.
Termination Resistor
The MAX13450E/MAX13451E feature a selectable inter-
nal termination resistor. Drive the TERM input low to
enable the internal termination resistor. Drive the TERM
input high to disable the internal termination resistor.
Drive the TERM100 input high to select the 100I termi-
nation resistor. Drive TERM100 input low to select the
120I termination resistor.
INV Input (MAX13451E)
The INV input of the MAX13451E reverses the polarity
of the RO receiver output (see Table 5 and 6). If the INV
input is high then the RO output is low under fail-safe
receiver conditions. This is the opposite polarity of nor-
mal fail-safe operations.
Fault Condition (MAX13451E)
The MAX13451E also has a FAULT output to indicate a
fault condition. The FAULT output is active high when
there is a short circuit at the driver’s output, an over/
undervoltage at the driver’s outputs, or the device’s tem-
perature is higher than +150NC.
Table 6. INV Input Function Table for
Receiver (MAX13451E)
Function Tables (continued) Functional Diagram (MAX13450E)
MAX13450E
D
LOGIC-LEVEL
TRANSLATION
SRL
DI
DE
TERM
Z
Y
A
B
RE
RO
TERM100
GND
VLVCC
INPUT OUTPUT
RE INV A-B RO
High X X High-Z
Low
Low
R -50mV or
Short or Open High
P -200mV Low
High
R -50mV or
Open Low
P -200mV High
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13
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Thermal Shutdown
When the devices’ temperature goes over +150NC, the
termination resistor turns off, and the transmitter shuts
down while the receiver stays active.
Fail Safe
The MAX13450E guarantee a logic-high receiver output
when the receiver inputs are shorted or open, or when
they are connected to a terminated transmission line with
all drivers disabled. This is done by setting the receiver
input threshold between -50mV and -200mV. If the dif-
ferential receiver input voltage (A - B) is greater than
or equal to -50mV, RO is logic-high. If (A - B) is less
than or equal to -200mV, RO is logic-low. In the case
of a terminated bus with all transmitters disabled, the
receiver’s differential input voltage is pulled to 0V by the
termination resistor. With the receiver thresholds of the
MAX13450E, this results in RO being logic-high.
The MAX13451E has the same fail-safe receiver behavior
as the MAX13450E when the INV input is low. When the
INV input is high, RO is low under the fail-safe condition.
ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against elec-
trostatic discharges encountered during handling and
assembly. The driver outputs and receiver inputs of the
MAX13450E/MAX13451E have extra protection against
static electricity. The ESD structures withstand high ESD
in all states: normal operation, shutdown, and powered
down. After an ESD event, the MAX13450E/MAX13451E
keep working without latchup or damage.
ESD protection can be tested in various ways. The trans-
mitter outputs and receiver inputs of the MAX13450E/
MAX13451E are characterized for protection to the fol-
lowing limits:
• Q30kV using the Human Body Model
• Q15kV using the Air Gap Discharge Method specified
in IEC 61000-4-2
• Q7kV using the Contact Discharge Method specified
in IEC 61000-4-2
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents test
setup, test methodology, and test results.
Human Body Model
Figure 11a shows the Human Body Model, and Figure
11b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of a
100pF capacitor charged to the ESD voltage of interest,
which is then discharged into the test device through a
1.5kI resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. However, it does not
specifically refer to integrated circuits. The MAX13450E/
MAX13451E help equipment designs to meet IEC 61000-
4-2, without the need for additional ESD-protection
components. The major difference between tests done
using the Human Body Model and IEC 61000-4-2 is
higher peak current in IEC 61000-4-2 because series
resistance is lower in the IEC 61000-4-2 model. Hence,
the ESD withstand voltage measured to IEC 61000-4-2
is generally lower than that measured using the Human
Body Model. Figure 11c shows the IEC 61000-4-2 model,
and Figure 11d shows the current waveform for the IEC
61000-4-2 ESD Contact Discharge test.
Applications Information
Typical Applications
The MAX13450E transceiver is designed for full-duplex,
bidirectional data communications on point-to-point
or multipoint bus transmission lines (Figure 12). The
MAX13451E transceiver is designed for half-duplex,
bidirectional data communications on point-to-point or
multipoint bus transmission lines (Figure 13).
256 Transceivers on the Bus
The standard RS-485 receiver input impedance is one-
unit load, and the standard driver can drive up to 32-unit
loads. The MAX13450E/MAX13451E have a 1/8-unit load
receiver input impedance, allowing up to 256 transceiv-
ers to be connected in parallel on one communication
line. Any combination of these devices, as well as other
RS-485 transceivers with a total of 32-unit loads or fewer,
can be connected to the line.
Reduced EMI and Reections
The MAX13450E/MAX13451E feature reduced slew-rate
drivers that minimize EMI and reduce reflections caused
by improperly terminated cables, allowing error-free data
transmission up to 500kbps.
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14
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Figure 11a. Human Body ESD Test Model
Figure 11b. Human Body Current Waveform
Figure 11c. IEC 61000-4-2 ESD Test Model
Figure 11d. IEC 61000-4-2 ESD Generator Current Waveform
Figure 12. Full-Duplex, Multidrop (MAX13450E)
Typical Application Circuits
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
CS
100pF
RC
1MΩ
RD
1500Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
IP 100%
90%
36.8%
tRL TIME
tDL
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
10%
0
0
AMPS
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
CS
150pF
RC
50MΩ TO 100MΩ
RD
330Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
tr = 0.7ns TO 1ns 30ns
60ns
t
100%
90%
10%
IPEAK
I
MAX13450E
D
Z
Y
B
A
B
A
Z
Y
R
MAX13450E
R
D
D
SLAVE 1
MASTER END SLAVE
R
D
SLAVE 2
R
D
SLAVE N
R
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15
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Low-Power Shutdown Mode
Drive RE high, DE low, and TERM high to enter low-
power shutdown mode (see Table 2).
Figure 13. Half-Duplex, Multidrop, and Point-to-Point Systems (MAX13451E)
Typical Application Circuits (continued)
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, 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.
D
SLAVE 1
R
D
SLAVE 2
R
D
SLAVE N
R
D
B
A
R
D
B
A
R
MAX13451E MAX13451E
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN
NO.
14 TSSOP-EP U14E+3 21-0108 90-0119
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16
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 4/10 Initial release —
1 11/10 Updated the VL specification in the Electrical Characteristics and Switching
Characteristics tables 2–5
2 2/15 Added the Benefits and Features section 1
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2015 Maxim Integrated Products, Inc.
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17
MAX13450E/MAX13451E RS-485 Transceivers with Integrated
100Ω/120Ω Termination Resistors
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.
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