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19-5254; Rev 0; 4/10
RS-485 Transceivers with Integrated 100/120 Termination Resistors
General Description
The MAX13450E/MAX13451E are half-duplex and fullduplex RS-485/RS-422 transceivers. These devices feature 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. Resistors
S Driver Drives 100I Double Termination S 20Mbps (max) Data Rate S Pin-Selectable Slew-Rate Limiting S Logic Supply Input Allows Interfacing Down to 1.8V S Driver Fault-Indication Output (MAX13451E) S Inverting of A, B Line Polarity (MAX13451E) S High-Impedance Driver Output/Receiver Input
Features
S 100I/120I Pin-Selectable Internal Termination
MAX13450E/MAX13451E
When VCC Supply is Removed
S Hot-Swap Input Structure on DE, RE, and TERM S Extended ESD Protection
30kV Human Body Model 15kV Air Gap Discharge per IEC 61000-4-2 7kV Contact Discharge per IEC 61000-4-2
S 1/8-Unit Load Allows Up to 256 Transceivers on
the Bus
S Thermal and Overcurrent Protected S Fail-Safe Receivers S +4.5V to +5.5V Supply Voltage Range
Applications
Industrial Control Systems Portable Industrial Equipment Motor Control Security Networks Medical Networks
Functional Diagram (MAX13451E)
VL VCC
SRL INV DI FAULT DE TERM LOGIC LOGIC-LEVEL TRANSLATION RE A B D
MAX13451E
Ordering Information/ Selector Guide
PART MAX13450EAUD+ MAX13451EAUD+ HALF/FULL DUPLEX Full Half PIN-PACKAGE 14 TSSOP-EP* 14 TSSOP-EP*
Note: All devices are specified over the -40C to +125C operating temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad.
RO
TERM100 GND
_______________________________________________________________ Maxim Integrated Products 1
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.
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
ABSOLUTE MAXIMUM RATINGS
(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) 14-Pin TSSOP (derate 25.6mW/NC above +70NC) .....2051mW Package Junction-to-Ambient Thermal Resistance (BJA) (Note 1) ...........................................39NC/W Package Junction-to-Case Thermal Resistance (BJC) (Note 1) ..............................................3NC/W Operating Temperature Range ....................... -40NC to +125NC Storage Temperature Range .......................... -65NC to +150NC Junction Temperature ....................................................+150NC Lead Temperature (soldering, 10s) ...............................+300NC Soldering Temperature (reflow) ......................................+260NC
Note 1: 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.
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.
ELECTRICAL CHARACTERISTICS
(VCC = +4.5V to +5.5V, VL = +1.62V to 4.2V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, VL = +1.8V, and TA = +25NC.) (Note 2) PARAMETER Supply Voltage Logic Supply Voltage Supply Current Logic Supply Current SYMBOL VCC VL ICC IL DE = RE = high, TERM = high, no load DE = RE = low, TERM = low, no load Current into VL, no load on RO, device not switching, DE = RE = high Current into VCC, DE = low, RE = TERM = high Current into VCC, DE = low, RE = high, TERM = low RDIFF = 100I, Figure 1 (Note 3) RDIFF = 46I, Figure 1 (Note 3) RDIFF = 100I or 46I, Figure 1 (Note 3) RDIFF = 100I or 46I, Figure 1 (Note 3) RDIFF = 100I or 46I, Figure 1 (Note 3) 0V P VOUT P +12V -7V P VOUT P 0V (VCC - 1V) P VOUT P +12V -7V P VOUT P 0V VCC/2 2.0 1.5 CONDITIONS MIN 4.5 1.62 1.8 TYP MAX 5.5 4.2 6 12 2 30 8 UNITS V V mA FA FA mA
Shutdown Current
ISHDN
DRIVER Differential Driver Output Change in Magnitude of Differential Output Voltage Driver Common-Mode Output Voltage Change In Magnitude of Common-Mode Voltage Driver Short-Circuit Output Current Driver Short-Circuit Foldback Output Current VOD DVOD VOC DVOC IOSD IOSDF VCC VCC 0.2 3 0.2 +280 -250 +15 -15 V V V V mA mA
2
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RS-485 Transceivers with Integrated 100/120 Termination Resistors
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +4.5V to +5.5V, VL = +1.62V to 4.2V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, VL = +1.8V, and TA = +25NC.) (Note 2) PARAMETER RECEIVER Input Current (A and B) IA, B DE = RE = GND; TERM = VL; VCC = GND or 5.5V -7V P VCM P +12V, DE = RE = GND; TERM = VL; VCC = GND VA + VB = 0V DI, DE, RE, TERM, SRL, TERM100, INV DI, DE, RE, TERM, SRL, TERM100, INV DI, DE, RE, TERM, TERM100, SRL, INV IOUT = -1mA IOUT = +1mA 0V P VRO P VL 0V P VRO P VL Fault condition, IOUT = -1mA Nonfault condition; IOUT = +1mA -1 Q1 VL - 0.6 0.4 +0.01 -1 VL - 0.6 0.4 +1 Q80 2/3 x VL 1/3 x VL +1 VA or VB = +12V VA or VB = -7V VA or VB = +12V -100 -200 15 -50 125 FA SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX13450E/MAX13451E
Receiver Differential Threshold Voltage Receiver Input Hysteresis LOGIC INTERFACE Input High Voltage Input Low Voltage Input Current Receiver Output High Voltage Receiver Output Low Voltage Three-State Output Current at Receiver Receiver Output Short-Circuit Current Fault Output High Voltage (MAX13451E) Fault Output Low Voltage (MAX13451E) TERMINATION RESISTOR 100I Termination Resistor 120I Termination Resistor Single-Ended Input Capacitance vs. GND ESD PROTECTION
VTH DVTH VIH VIL IIN VROH VROL IOZR IOSR VFAULTH VFAULTL
mV mV V V FA V V FA mA V V
R100 R120 CIN
TERM = low, TERM100 = high TERM = low, TERM100 = low f = 1MHz (MAX13451E only)
85 101
100 120 40
115 139
I I pF
Human Body Model ESD Protection (A, B, Y, Z) ESD Protection (All Other Pins) IEC 61000-4-2 Air Gap Discharge IEC 61000-4-2 Contact Discharge Human Body Model
Q30 Q15 Q7 Q2 kV
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RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
SWITCHING CHARACTERISTICS--SRL = HIGH
(VCC = +4.5V to +5.5V, VL = +1.62V to 4.2V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, VL = +1.8V and TA = +25NC.) (Note 2) PARAMETER DRIVER Driver Propagation Delay Differential Driver Output Skew |tDPLH - tDPHL| Driver Differential Output Rise or Fall Time Maximum Data Rate Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Driver Disable Delay Driver Enable Delay RECEIVER Receiver Propagation Delay Receiver Output Skew Maximum Data Rate Receiver Enable to Output High Receiver Enable to Output Low Receiver Disable from High Receiver Disable from Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low TERMINATION RESISTOR Turn-Off Time Turn-On Time tRTZ tRTEN Figure 10 Figure 10 120 1 Fs Fs tRPLH tRPHL tRSKEW DRMAX tRZH tRZL tRHZ tRLZ S2 closed, CL = 100pF, RL = 500I, Figures 8 and 9 S1 closed, CL = 100pF, RL = 500I, Figures 8 and 9 Figures 8 and 9 Figures 8 and 9 CL = 15pF, |VID| R 2.0V; tLH, tHL P 15ns, Figures 6 and 7 CL = 15pF, Figures 6 and 7 500 50 50 50 50 5000 5000 200 200 30 ns ns kbps ns ns ns ns ns ns tDPLH tDPHL tDSKEW tHL tLH DRMAX S2 closed, RL = 500I, CL = 100pF, tDZH(SHDN) Figures 4 and 5 tDZL(SHDN) tDLZ, tDHZ tDZL, tDZH S1 closed, RL = 500I, CL = 100pF, Figures 4 and 5 Figures 4 and 5 Figures 4 and 5 RDIFF = 54I, CL = 50pF, Figures 2 and 3 RDIFF = 54I, CL = 50pF, Figure 3 RDIFF = 54I, CL = 50pF, Figures 2 and 3 100 100 500 4500 5200 100 2500 800 800 100 600 600 ns ns ns kbps ns ns ns ns SYMBOL CONDITIONS MIN TYP MAX UNITS
tRZH(SHDN) Figures 8 and 9 tRZL(SHDN) Figures 8 and 9
4
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RS-485 Transceivers with Integrated 100/120 Termination Resistors
SWITCHING CHARACTERISTICS--SRL = LOW
(VCC = +4.5V to +5.5V, VL = +1.62V to 4.2V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, VL = +1.8V, and TA = +25NC.) (Note 2) PARAMETER DRIVER Driver Propagation Delay Differential Driver Output Skew |tDPLH - tDPHL| Driver Differential Output Rise or Fall Time Maximum Data Rate Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Driver Disable Delay Driver Enable Delay RECEIVER Receiver Propagation Delay Receiver Output Skew Maximum Data Rate Receiver Enable to Output High Receiver Enable to Output Low Receiver Disable Time from High Receiver Disable Time from Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low TERMINATION RESISTOR Turn-Off Time Turn-On Time tRTZ tRTEN Figure 10 Figure 10 120 1 Fs Fs tRPLH tRPHL tRSKEW DRMAX tRZH tRZL tRHZ tRLZ S2 closed, CL = 100pF, RL = 500I, Figures 8 and 9 S1 closed, CL = 100pF, RL = 500I, Figures 8 and 9 Figures 8 and 9 Figures 8 and 9 CL = 15pF, |VID| R 2.0V; tLH, tHL P 15ns, Figures 6 and 7 CL = 15pF, Figures 6 and 7 20 50 50 50 50 2000 2000 50 50 6 ns ns Mbps ns ns ns ns ns ns tDPLH tDPHL tDSKEW tHL, tLH DRMAX S2 closed, RL = 500I, CL = 100pF, tDZH(SHDN) Figures 4 and 5 tDZL(SHDN) tDLZ, tDHZ tDZL, tDZH S1 closed, RL = 500I, CL = 100pF, Figures 4 and 5 Figures 4 and 5 Figures 4 and 5 RDIFF = 54I, CL = 50pF, Figures 2 and 3 RDIFF = 54I, CL = 50pF, Figure 3 RDIFF = 54I, CL = 50pF, Figures 2 and 3 20 2000 2000 100 100 50 50 6 15 ns ns ns Mbps ns ns ns ns SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX13450E/MAX13451E
tRZH(SHDN) Figures 8 and 9 tRZL(SHDN) Figures 8 and 9
Note 2: All devices are 100% production tested at TA = +25C. Limits over temperature are guaranteed by design. Note 3: Termination resistance is disabled (TERM = high).
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5
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
Typical Operating Characteristics
(VCC = +5V, VL = +1.8V, TA = +25NC, unless otherwise noted.)
SUPPLY CURRENT vs. DATA RATE
MAX13450E/51E toc01
SHUTDOWN CURRENT vs. TEMPERATURE
MAX13450E/51E toc02
RECEIVER OUTPUT VOLTAGE vs. OUTPUT CURRENT
SOURCE
4 3 2 1
MAX13450E/51E toc03
70 60 SUPPLY CURRENT (mA) 50 40 30 20 10 0 0.1 1 10
10 9 SHUTDOWN CURRENT (A) 8 7 6 5 4 3 2 1 0
5 RECEIVER OUTPUT VOLTAGE (V)
RL = 54 RL = 100
NO LOAD
100
SINK
0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) 0 10 20 30 40 50 60 70 OUTPUT CURRENT (mA)
DATA RATE (Mbps)
RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE
IOUT = 1mA
MAX13450E/51E toc04
RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE
MAX13450E/51E toc05
RECEIVER PROPAGATION DELAY vs. TEMPERATURE
RECEIVER PROPAGATION DELAY (ns)
IOUT = 1mA
RECEIVER OUTPUT HIGH VOLTAGE (V)
1.8 1.6 1.4 1.2 1.0
RECEIVER OUTPUT LOW VOLTAGE (V)
INV = HIGH
80 60 40 20 0
0.4 0.3 0.2 0.1 0
INV = LOW
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
DRIVER DIFFERENTIAL OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE
DRIVER DIFFERENTIAL OUTPUT CURRENT (mA)
MAX13450E/51E toc07
TRANSMITTER OUTPUT CURRENT vs. TRANSMITTER OUTPUT HIGH VOLTAGE
MAX13450E/51E toc08
TRANSMITTER OUTPUT CURRENT vs. TRANSMITTER OUTPUT LOW VOLTAGE
TRANSMITTER OUTPUT CURRENT (mA) 180 160 140 120 100 80 60 40 20 0 -3 2 7 12
MAX13450E/51E toc09
100 80 60 40 20 0 0 1 2 3 4
120 TRANSMITTER OUTPUT CURRENT (mA) 100 80 60 40 20 0
200
5
-7
-2
3
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
TRANSMITTER OUTPUT HIGH VOLTAGE (V)
TRANSMITTER OUTPUT LOW VOLTAGE (V)
6
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MAX13450E/51E toc06
2.0
0.5
100
RS-485 Transceivers with Integrated 100/120 Termination Resistors
Typical Operating Characteristics (continued)
(VCC = +5V, VL = +1.8V, TA = +25NC, unless otherwise noted.)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
MAX13450E/MAX13451E
100 TERMINATION RESISTOR vs. FREQUENCY
140 120 100 80 60 40 -10 PHASE (DEGREE)
MAX13450E/51E toc11
RDIFF = 54
4 3 2 1 0
MAX13450E/51E toc10
5
0
MAGNITUDE ()
R100 MAGNITUDE R100 PHASE
-20
20 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) 0.1 1 10 100 FREQUENCY (MHz) -30
120 TERMINATION RESISTOR vs. FREQUENCY
140 120 100 80 60 40 20 0 0.1 1 10 100 FREQUENCY (MHz) -30
MAX13450E/51E toc12
TERMINATION RESISTANCE vs. TEMPERATURE
MAX13450E/51E toc13 MAX13450E/51E toc15
0 TERMINATION RESISTANCE ()
130 120 110 100 90 80
120 RESISTOR
MAGNITUDE ()
R120 MAGNITUDE
-10
PHASE (DEGREE)
R120 PHASE
-20
100 RESISTOR
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
DRIVER PROPAGATION DELAY (250kbps) (MAX13451E)
MAX13450E/51E toc14
DRIVER ENABLE TIME FROM SHUTDOWN (MAX13451E)
SRL = HIGH DE = HIGH RE = HIGH
DI 1V/div
DE 2V/div A 2V/div
A 1V/div
B 1V/div 1s/div 200ns/div
SRL = LOW RE = HIGH
B 2V/div
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7
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
Test Circuits and Waveforms
A/Y RDIFF VL DE 2 DI VOD CL A VID B RDIFF CL
RDIFF B/Z
2
VOC
Figure 1. Driver DC Test Load
Figure 2. Driver Timing Test Circuit
VL DI 0V VL/2
f = 1MHz, tLH 3ns, tHL 3ns VL/2 1/2 VO
tDPLH B A 1/2 VO VO VO VDD 0V -VO 10% tLH tDSKEW = |tDPLH - tDPHL| 90%
tDPHL
90%
10% tHL
Figure 3. Driver Propagation Delays
8
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RS-485 Transceivers with Integrated 100/120 Termination Resistors
Test Circuits and Waveforms (continued)
VL DE 0V tDZL(SHDN),tDZL VCC A/Y, B/Z VOL VOH A/Y, B/Z 0V tDZH(SHDN),tDZH tDHZ VOH/2 (VCC + VOL)/2 OUTPUT NORMALLY LOW OUTPUT NORMALLY HIGH VOH - 0.25V VOL + 0.25V tDLZ VL/2 VL/2
MAX13450E/MAX13451E
Figure 4. Driver Enable and Disable Times
OUTPUT UNDER TEST CL
500
S1
VCC ATE VID
B R A RECEIVER OUTPUT
S2
Figure 5. Driver-Enable and Disable-Timing Test Load
Figure 6. Receiver Propagation Delay Test Circuit
A B
f = 1MHz, tLH 3ns, tHL 3ns
1V -1V
tRPHL VROH RO VROL VL/2
tRPLH
VL/2 tRSKEW = |tRPHL - tRPLH|
Figure 7. Receiver Propagation Delays
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9
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
Test Circuits and Waveforms (continued)
VL RE 0V tRZL(SHDN), tRZL VL RO VROL VROH RO 0V DI = 0V tRZH(SHDN), tRZH tRHZ VROH/2 (VL + VROL)/2 OUTPUT NORMALLY LOW OUTPUT NORMALLY HIGH ROH - 0.25V tRHZ ROH + 0.25V VL/2 VL/2
Figure 8. Receiver Enable and Disable Times
500 RO CL
S1
VCC
S2
Figure 9. Receiver Enable and Disable Times
IA = VAB/RD A RO RECEIVER TERM B TERM 0V VL VL/2
VAB = VA - VB RD = R100 OR R200
tREN IA 90%
tREN
10%
Figure 10. Termination Resistor Turn-On/-Off Times
10
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RS-485 Transceivers with Integrated 100/120 Termination Resistors
Pin Configurations
TOP VIEW +
DE RE DI VCC TERM VL RO 1 2 3 4 5 6 7 EP MAX13450E 14 13 12 11 10 9 8 SRL TERM100 Z GND Y B A
MAX13450E/MAX13451E
TOP VIEW +
DE RE DI VCC TERM VL RO 1 2 3 4 5 6 7 EP MAX13451E 14 13 12 11 10 9 8 SRL TERM100 B GND A FAULT INV
TSSOP
TSSOP
Pin Description
PIN MAX13450E 1 MAX13451E 1 NAME DE FUNCTION 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. 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. 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 output low. DI is referenced to VL. Power-Supply Voltage. Bypass VCC to GND with a 0.1FF ceramic capacitor placed as close as possible to the device. Active-Low Termination Resistor Enable. Drive TERM low to enable the internal termination resistor. TERM is referenced to VL. Logic Supply Voltage. Bypass VL to GND with a 0.1FF ceramic capacitor placed as close as possible to the device. 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. 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. Noninverting Receiver Input 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. Inverting Receiver Input 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.
2
2
RE
3
3
DI
4 5 6 7
4 5 6 --
VCC TERM VL RO
-- 8 -- 9 --
7 -- 10 -- 12
RO A A B B
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11
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
Pin Description (continued)
PIN MAX13450E 10 11 12 13 MAX13451E -- 11 -- 13 NAME Y GND Z TERM100 Noninverting Driver Output Ground Inverting Driver Output Termination Resistor Value Selection Input. Drive TERM100 low to select a 120I termination and high to select a 100I termination. The TERM100 input is referenced to VL. 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. Inversion Input. Drive INV high to internally swap RO logic level with respect to A and B signals. 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. Exposed Pad FUNCTION
14 -- -- --
14 8 9 --
SRL INV FAULT EP
Function Tables
Table 1. Termination Resistor Control (MAX13450E/MAX13451E)
TERM Low High DE X X RE X X TERMINATION RESISTOR Activated Not activated RE High Low
Table 4. Function Table for Receiver (MAX13450E)
INPUT A-B X R -50mV or Open P -200mV OUTPUT RO High-Z High Low
Table 2. Shutdown Control (MAX13450E/ MAX13451E)
DE Low RE High TERM High STATE Shutdown
Table 5. INV Input Function Table for Transmitter (MAX13451E)
INPUT DE Low INV X Low High High DI X Low High Low High A High-Z Low High High Low OUTPUT B High-Z High Low Low High
Table 3. Function Table for Transmitter (MAX13450E)
INPUT DE Low High DI X Low High Y High-Z Low High OUTPUT Z High-Z High Low
12
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RS-485 Transceivers with Integrated 100/120 Termination Resistors
Function Tables (continued)
Table 6. INV Input Function Table for Receiver (MAX13451E)
INPUT RE High INV X Low Low High A-B X R -50mV or Short or Open P -200mV R -50mV or Open P -200mV OUTPUT RO High-Z High Low Low High
TERM LOGIC-LEVEL TRANSLATION RE B DI D Y DE
Functional Diagram (MAX13450E)
VL VCC
MAX13450E/MAX13451E
SRL Z
MAX13450E
Detailed Description
The MAX13450E is a full-duplex, RS-485/RS-422compatible transceiver and the MAX13451E is a halfduplex, 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 transceivers 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 logiclevel 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. The MAX13450E/MAX13451E feature a selectable internal termination resistor. Drive the TERM input low to enable the internal termination resistor. Drive the TERM input high to disable the internal termination resistor.
RO
A TERM100 GND
Drive the TERM100 input high to select the 100I termination resistor. Drive TERM100 input low to select the 120I termination resistor. 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 normal fail-safe operations. 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 temperature is higher than +150NC.
INV Input (MAX13451E)
Fault Condition (MAX13451E)
Termination Resistor
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13
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
When the devices' temperature goes over +150NC, the termination resistor turns off, and the transmitter shuts down while the receiver stays active. 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 differential 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. As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic 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 transmitter outputs and receiver inputs of the MAX13450E/ MAX13451E are characterized for protection to the following 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.
Thermal Shutdown
Fail Safe
Human Body Model Figure 11a shows the Human Body Model, and Figure 11b 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 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 610004-2, 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.
ESD Protection
Applications Information
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). The standard RS-485 receiver input impedance is oneunit 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 transceivers 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. 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.
Typical Applications
256 Transceivers on the Bus
Reduced EMI and Reflections
14
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RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
RC 1M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST HIGHVOLTAGE DC SOURCE RC 50M TO 100M CHARGE-CURRENT LIMIT RESISTOR RD 330 DISCHARGE RESISTANCE DEVICE UNDER TEST
CS 100pF
STORAGE CAPACITOR
CS 150pF
STORAGE CAPACITOR
Figure 11a. Human Body ESD Test Model
Figure 11c. IEC 61000-4-2 ESD Test Model
I 100% 90% IPEAK
IP 100% 90% AMPS 36.8% 10% 0 0 tRL
Ir
PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
10% TIME tDL CURRENT WAVEFORM tr = 0.7ns TO 1ns 30ns 60ns t
Figure 11b. Human Body Current Waveform
Figure 11d. IEC 61000-4-2 ESD Generator Current Waveform
Typical Application Circuits
Z D Y B R A Y A Z D B R
MAX13450E MASTER R D D R D R
MAX13450E END SLAVE
SLAVE 1
SLAVE 2
SLAVE N
Figure 12. Full-Duplex, Multidrop (MAX13450E) ______________________________________________________________________________________ 15
RS-485 Transceivers with Integrated 100/120 Termination Resistors MAX13450E/MAX13451E
Typical Application Circuits (continued)
MAX13451E D B B
MAX13451E D
A
A
R
R
R D D
R D
R
SLAVE 1
SLAVE 2
SLAVE N
Figure 13. Half-Duplex, Multidrop, and Point-to-Point Systems (MAX13451E)
Drive RE high, DE low, and TERM high to enter lowpower shutdown mode (see Table 2).
Low-Power Shutdown Mode
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 14 TSSOP-EP PACKAGE CODE U14E+3 DOCUMENT NO. 21-0108
Chip Information
PROCESS: BiCMOS
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RS-485 Transceivers with Integrated 100/120 Termination Resistors
Revision History
REVISION NUMBER 0 REVISION DATE 4/10 Initial release DESCRIPTION PAGES CHANGED --
MAX13450E/MAX13451E
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
(c)
17
2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.

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