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19-1474; Rev 0; 4/99
3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
General Description
Devices in the MAX3483E family (MAX3483E/MAX3485E/ MAX3486E/MAX3488E/MAX3490E/MAX3491E) are 15kV ESD-protected, +3.3V, low-power transceivers for RS-485 and RS-422 communications. Each device contains one driver and one receiver. The MAX3483E and MAX3488E feature slew-rate-limited drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission at data rates up to 250kbps. The partially slew-rate-limited MAX3486E transmits up to 2.5Mbps. The MAX3485E, MAX3490E, and MAX3491E transmit at up to 12Mbps. All devices feature enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to 15kV using IEC 1000-4-2 AirGap Discharge, 8kV using IEC 1000-4-2 Contact Discharge, and 15kV using the Human Body Model. Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if both inputs are open circuit. The MAX3488E, MAX3490E, and MAX3491E feature full-duplex communication, while the MAX3483E, MAX3485E, and MAX3486E are designed for halfduplex communication.
Features
o ESD Protection for RS-485 I/O Pins 15kV--Human Body Model 8kV--IEC 1000-4-2, Contact Discharge 15kV--IEC 1000-4-2, Air-Gap Discharge o Operate from a Single +3.3V Supply-- No Charge Pump Required o Interoperable with +5V Logic o Guaranteed 12Mbps Data Rate (MAX3485E/MAX3490E/MAX3491E) o Slew-Rate Limited for Errorless Data Transmission (MAX3483E/MAX3488E) o 2nA Low-Current Shutdown Mode (MAX3483E/MAX3485E/MAX3486E/MAX3491E) o -7V to +12V Common-Mode Input Voltage Range o Full-Duplex and Half-Duplex Versions Available o Industry-Standard 75176 Pinout (MAX3483E/MAX3485E/MAX3486E) o Current-Limiting and Thermal Shutdown for Driver Overload Protection
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
Ordering Information
PART TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP MAX3483ECSA MAX3483ECPA MAX3483EESA MAX3483EEPA MAX3485ECSA MAX3485ECPA MAX3485EESA MAX3485EEPA
Applications
Telecommunications Industrial-Control Local Area Networks Transceivers for EMI-Sensitive Applications Integrated Services Digital Networks Packet Switching
Ordering Information continued at end of data sheet.
Selector Guide
PART NUMBER MAX3483E MAX3485E MAX3486E MAX3488E MAX3490E MAX3491E GUARANTEED SUPPLY DATA RATE VOLTAGE (Mbps) (V) 0.25 12 2.5 0.25 12 12 3.0 to 3.6 DRIVER/ SHUTDOWN 15kV HALF/FULL SLEW-RATE RECEIVER CURRENT ESD DUPLEX LIMITED ENABLE (nA) PROTECTION Half Half Half Full Full Full Yes No Yes Yes No No Yes Yes Yes No No Yes 2 2 2 -- -- 2 Yes Yes Yes Yes Yes Yes PIN COUNT 8 8 8 8 8 14 1
________________________________________________________________ Maxim Integrated Products
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC).............................................................+7V Control Input Voltage (RE, DE).................................-0.3V to +7V Driver Input Voltage (DI)...........................................-0.3V to +7V Driver Output Voltage (A, B, Y, Z) .......................-7.5V to +12.5V Receiver Input Voltage (A, B)..............................-7.5V to +12.5V Receiver Output Voltage (RO)....................-0.3V to (VCC + 0.3V) Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.88mW/C above +70C)..................471mW 8-Pin Plastic DIP (derate 9.09mW/C above +70C) .....727mW 14-Pin SO (derate 8.33mW/C above +70C)................667mW 14-Pin Plastic DIP (derate 10mW/C above +70C) ......800mW Operating Temperature Ranges MAX34_ _ EC_ _ ...................................................0C to +70C MAX34_ _ EE_ _.................................................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+300C
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 = +3.3V 0.3V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Differential Driver Output Change in Magnitude of Driver Differential Output Voltage for Complementary Output States (Note 1) Driver Common-Mode Output Voltage Change in Magnitude of Common-Mode Output Voltage (Note 1) Input High Voltage Input Low Voltage Logic Input Current Input Current (A, B) Output Leakage (Y, Z) Output Leakage (Y, Z) in Shutdown Mode Receiver Differential Threshold Voltage Receiver Input Hysteresis Receiver Output High Voltage Receiver Output Low Voltage Three-State (High-Impedance) Output Current at Receiver Receiver Input Resistance Supply Voltage Range Supply Current Supply Current in Shutdown Mode 2 SYMBOL VOD CONDITIONS RL = 100 (RS-422), Figure 4 RL = 54 (RS-485), Figure 4 RL = 60 (RS-485), VCC = 3.3V, Figure 5 RL = 54 or 100, Figure 4 MIN 2.0 1.5 1.5 0.2 TYP MAX UNITS V
VOD
V
VOC VOC VIH VIL IIN1 IIN2 IO IO VTH VTH VOH VOL IOZR RIN VCC ICC ISHDN
RL = 54 or 100, Figure 4 RL = 54 or 100, Figure 4 DE, DI, RE DE, DI, RE DE, DI, RE DE = 0, VCC = 0 or 3.6V VIN = 12V VIN = -7V VOUT = 12V DE = 0, RE = 0, VCC = 0 or 3.6V, MAX3491E VOUT = -7V VOUT = 12V DE = 0, RE = VCC, VCC = 0 or 3.6V, MAX3491E VOUT = -7V -7V VCM 12V VCM = 0 IOUT = -1.5mA, VID = 200mV, Figure 6 IOUT = 2.5mA, VID = 200mV, Figure 6 VCC = 3.6V, 0 VOUT VCC -7V VCM 12V No load, DI = 0 or VCC DE = VCC, RE = 0 or VCC DE = 0, RE = 0 12 3.0 1.1 0.95 0.002 VCC - 0.4 -0.2 50 2.0
3
V
0.2
V V
0.8 2 1.0 -0.8 20 -20 1 -1 0.2
V A mA A A V mV V
0.4 1
V A k
3.6 2.2 1.9 1
V mA A
DE = 0, RE = VCC, DI = VCC or 0
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.3V 0.3V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Driver Short-Circuit Output Current Receiver Short-Circuit Output Current SYMBOL IOSD IOSR CONDITIONS VOUT = -7V VOUT = 12V 0 VRO VCC IEC 1000-4-2 Air Discharge IEC 1000-4-2 Contact Discharge (MAX3483E, MAX3485E, MAX3486E, MAX3491E) IEC 1000-4-2 Contact Discharge (MAX3490E, MAX3488E)* Human Body Model MIN TYP MAX -250 250 60 UNITS mA mA
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
8 15 8
ESD Protection for Y, Z, A, B
kV 6 15
*MAX3488E and MAX3491E will be compliant to 8kV per IEC 1000-4-2 Contact Discharge by September 1999.
DRIVER SWITCHING CHARACTERISTICS--MAX3485E/MAX3490E/MAX3491E
(VCC = +3.3V, TA = +25C.) PARAMETER Maximum Data Rate Driver Differential Output Delay Driver Differential Output Transition Time Driver Propagation Delay, Low-to-High Level Driver Propagation Delay, High-to-Low Level SYMBOL tDD tTD tPLH tPHL tPDS tPZL tPZH tPHZ tPLZ tPSL tPSH CONDITIONS RL = 60, Figure 7 RL = 60, Figure 7 RL = 27, Figure 8 RL = 27, Figure 8 RL = 27, Figure 8 RL = 110, Figure 10 RL = 110, Figure 9 RL = 110, Figure 9 RL = 110, Figure 10 RL = 110, Figure 10 RL = 110, Figure 9 MIN 12 1 3 7 7 TYP 15 22 11 23 23 -1.4 42 42 35 35 650 650 MAX 35 25 35 35 8 90 90 80 80 900 900 UNITS Mbps ns ns ns ns ns ns ns ns ns ns ns
|tPLH - tPHL| Driver Propagation-Delay Skew (Note 2)
Driver-Output Enable Time to Low Level Driver-Output Enable Time to High Level Driver-Output Disable Time from High Level Driver-Output Disable Time from Low Level Driver-Output Enable Time from Shutdown to Low Level Driver-Output Enable Time from Shutdown to High Level
DRIVER-OUTPUT ENABLE/DISABLE TIMES (MAX3485E/MAX3491E only)
DRIVER SWITCHING CHARACTERISTICS--MAX3486E
(VCC = +3.3V, TA = +25C.) PARAMETER Maximum Data Rate Driver Differential Output Delay Driver Differential Output Transition Time Driver Propagation Delay, Low-to-High Level Driver Propagation Delay, High-to-Low Level SYMBOL tDD tTD tPLH tPHL tPDS tPZL tPZH tPHZ tPLZ tPSL tPSH CONDITIONS RL = 60, Figure 7 RL = 60, Figure 7 RL = 27, Figure 8 RL = 27, Figure 8 RL = 27, Figure 8 RL = 110, Figure 10 RL = 110, Figure 9 RL = 110, Figure 9 RL = 110, Figure 10 RL = 110, Figure 10 RL = 110, Figure 9 MIN 2.5 20 15 20 20 TYP 42 28 42 42 -6 52 52 40 40 700 700 MAX 70 60 75 75 12 100 100 80 80 1000 1000 UNITS Mbps ns ns ns ns ns ns ns ns ns ns ns 3
|tPLH - tPHL| Driver Propagation-Delay Skew (Note 2)
DRIVER-OUTPUT ENABLE/DISABLE TIMES Driver-Output Enable Time to Low Level Driver-Output Enable Time to High Level Driver-Output Disable Time from High Level Driver-Output Disable Time from Low Level Driver-Output Enable Time from Shutdown to Low Level Driver-Output Enable Time from Shutdown to High Level
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
DRIVER SWITCHING CHARACTERISTICS--MAX3483E/MAX3488E
(VCC = +3.3V, TA = +25C.) PARAMETER Maximum Data Rate Driver Differential Output Delay Driver Differential Output Transition Time Driver Propagation Delay, Low-to-High Level Driver Propagation Delay, High-to-Low Level tDD tTD tPLH tPHL tPDS tPZL tPZH tPHZ tPLZ tPSL tPSH RL = 60, Figure 7 RL = 60, Figure 7 RL = 27, Figure 8 RL = 27, Figure 8 RL = 27, Figure 8 RL = 110, Figure 10 RL = 110, Figure 9 RL = 110, Figure 9 RL = 110, Figure 10 RL = 110, Figure 10 RL = 110, Figure 9 SYMBOL CONDITIONS MIN 250 600 400 700 700 900 740 930 930 50 900 600 50 50 1.9 2.2 1300 800 80 80 2.7 3.0 1400 1200 1500 1500 TYP MAX UNITS kbps ns ns ns ns ns ns ns ns ns s s
|tPLH - tPHL| Driver Propagation-Delay Skew (Note 2)
Driver-Output Enable Time to Low Level Driver-Output Enable Time to High Level Driver-Output Disable Time from High Level Driver-Output Disable Time from Low Level Driver-Output Enable Time from Shutdown to Low Level Driver-Output Enable Time from Shutdown to High Level
DRIVER-OUTPUT ENABLE/DISABLE TIMES (MAX3483E only)
RECEIVER SWITCHING CHARACTERISTICS
(VCC = +3.3V, TA = +25C.) PARAMETER Time to Shutdown Receiver Propagation Delay, Low-to-High Level Receiver Propagation Delay, High-to-Low Level SYMBOL tSHDN tRPLH tRPHL tRPDS tPRZL tPRZH tPRHZ tPRLZ tPRSL tPRSH CONDITIONS MAX3483E/MAX3485E/MAX3486E/MAX3491E only (Note 3) VID = 0 to 3.0V, CL = 15pF, Figure 11 MAX3483E/MAX3488E VID = 0 to 3.0V, CL = 15pF, Figure 11 MAX3483E/MAX3488E VID = 0 to 3.0V, CL = 15pF, Figure 11 MAX3483E/MAX3488E CL = 15pF, Figure 12, MAX3483E/85E/86E/91E only CL = 15pF, Figure 12, MAX3483E/85E/86E/91E only CL = 15pF, Figure 12, MAX3483E/85E/86E/91E only CL = 15pF, Figure 12, MAX3483E/85E/86E/91E only CL = 15pF, Figure 12, MAX3483E/85E/86E/91E only CL = 15pF, Figure 12, MAX3483E/85E/86E/91E only MIN 80 25 25 25 25 TYP 190 62 75 62 75 6 12 25 25 25 25 720 720 MAX 300 90 120 90 120 10 20 50 50 45 45 1400 1400 UNITS ns ns ns ns ns ns ns ns ns ns
|tPLH - tPHL| Receiver
Propagation-Delay Skew Receiver-Output Enable Time to Low Level Receiver-Output Enable Time to High Level Receiver-Output Disable Time from High Level Receiver-Output Disable Time from Low Level Receiver-Output Enable Time from Shutdown to Low Level Receiver-Output Enable Time from Shutdown to High Level
Note 1: VOD and VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 2: Measured on |tPLH (Y) - tPHL (Y)| and |tPLH (Z) - tPHL (Z)|. Note 3: The transceivers are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 80ns, the devices are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the devices are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section. 4 _______________________________________________________________________________________
3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
Typical Operating Characteristics
(VCC = +3.3V, TA = +25C, unless otherwise noted.)
OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE
MAX3483E-01
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE
MAX3483E-02
RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE
IRO = 1.5mA
MAX3483E-03
25
-20 -18 -16 OUTPUT CURRENT (mA) -14 -12 -10 -8 -6 -4 -2
3.30 3.25 OUTPUT HIGH VOLTAGE (V) 3.20 3.15 3.10 3.05 3.00
20 OUTPUT CURRENT (mA)
15
10
5
0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT LOW VOLTAGE (V)
0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT HIGH VOLTAGE (V)
-40
-20
0
20
40
60
80
100
TEMPERATURE (C)
RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE
MAX3483E-04
DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX3483E-05
DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE
DIFFERENTIAL OUTPUT VOLTAGE (V) 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 R = 54
MAX3483E-06
0.8 0.7 OUTPUT LOW VOLTAGE (V) 0.6 0.5 0.4 0.3 0.2 0.1 0 -40 -20 0 20 40
100 90 80 OUTPUT CURRENT (mA) 70 60 50 40 30 20 10 0
IRO = 2.5mA
2.6
60
80
100
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-40
-20
0
20
40
60
80
100
TEMPERATURE (C)
DIFFERENTIAL OUTPUT VOLTAGE (V)
TEMPERATURE (C)
OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGE
MAX3483E-07
OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGE
MAX3483E-08
175 150 OUTPUT CURRENT (mA) 125 100 75 50 25 0 0 2 4 6 8 10
-100
-80 OUTPUT CURRENT (mA) 12
-60
-40
-20
0 OUTPUT LOW VOLTAGE (V) -7 -6 -5 -4 -3 -2 -1 0 1 2 3 OUTPUT HIGH VOLTAGE (V) 4 5
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5
3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
X = DON'T CARE 1.1 SUPPLY CURRENT (mA) DE = VCC, RE = X DE = 0, RE = 0 0.9
MAX3483E-09
SHUTDOWN CURRENT vs. TEMPERATURE
90 SHUTDOWN CURRENT (nA) 80 70 60 50 40 30 20 10
MAX3483E-10
1.2
100
1.0
0.8 0.7 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
Pin Description
PIN MAX3483E MAX3485E MAX3486E 1 MAX3488E MAX3490E 2 NAME MAX3491E Receiver Output. If A > B by 200mV, RO will be high; if A < B by 200mV, RO will be low. Receiver Output Enable. RO is enabled when RE is low; RO is high impedance when RE is high. If RE is high and DE is low, the device will enter a low-power shutdown mode. Driver Output Enable. The driver outputs are enabled by bringing DE high. They are high impedance when DE is low. If RE is high and DE is low, the device will enter a low-power shutdown mode. If the driver outputs are enabled, the parts function as line drivers. While they are high impedance, they function as line receivers if RE is low. Driver Input. A low on DI forces output Y low and output Z high. Similarly, a high on DI forces output Y high and output Z low. Ground Noninverting Driver Output Inverting Driver Output Noninverting Receiver Input and Noninverting Driver Output Noninverting Receiver Input Inverting Receiver Input and Inverting Driver Output Inverting Receiver Input Positive Supply: 3.0V VCC 3.6V. Do not operate device with VCC > 3.6V. No Connection. Not internally connected. FUNCTION
2
RO
2
--
3
RE
3
--
4
DE
4 5 -- -- 6 -- 7 -- 8 -- 6
3 4 5 6 -- 8 -- 7 1 --
5 6, 7 9 10 -- 12 -- 11 13, 14 1, 8
DI GND Y Z A A B B VCC N.C.
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
TOP VIEW
RO
1
R
8 7 6
VCC B A GND
RO
1
R
RE 2 DE 3 DI 4 D
RE 2 DE 3 DI 4 D
5
8 VCC 7B Rt 6 A 5 GND
MAX3483E MAX3485E MAX3486E
B Rt A R
DE D DI
RO RE
SO/DIP
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH.
Figure 1. MAX3483E/MAX3485E/MAX3486E Pin Configuration and Typical Operating Circuit
TOP VIEW
VCC 1 5Y
VCC
MAX3488E MAX3490E
Rt 6Z
VCC 1 RO 2 DI 3 GND 4
R
8 7 6
A B Z Y
DI
3
D
R
RO
8A RO 2
D
5
R
Rt 7 B
D
DI
SO/DIP
4 GND GND
Figure 2. MAX3488E/MAX3490E Pin Configuration and Typical Operating Circuit
TOP VIEW
DE 4
VCC 13, 14 9 Y Rt 10 Z 12 A Rt 11 B
VCC RE
MAX3491E
N.C. 1 RO 2 RE 3 DE 4 DI 5 GND 6 GND 7 D R
14 VCC 13 VCC 12 A 11 B 10 Z 9 8 Y N.C. N.C. 1, 8 3 RO 2 DI 5
D
R
RO
R
D
DI
SO/DIP
6, 7 RE GND
GND
DE
Figure 3. MAX3491E Pin Configuration and Typical Operating Circuit
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
375 RL 2 D VOD RL VCC 2 D VOC VOD RL VCM = -7V to +12V
VCC
375
Figure 4. Driver VOD and VOC
Figure 5. Driver VOD with Varying Common-Mode Voltage
VID
R
0 VOL IOL (+) VOH IOH (-)
Figure 6. Receiver VOH and VOL
3V IN CL D GENERATOR (NOTE 4) 50 VCC CL CL = 15pF (NOTE 5) 90% OUT 50% 10% tTD 90% 50% 10% tTD RL = 60 OUT tDD tDD 1.5V 1.5V 0
2.0V -2.0V
Figure 7. Driver Differential Output Delay and Transition Times
8
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
3V VOM IN RL = 27 S1 D GENERATOR (NOTE 4) 50 VCC VOH + VOL 2 OUT CL = 15pF (NOTE 5) Y OUT tPLH tPHL VOH VOM VOM VOL 1.5V 1.5V 0V
VOM =
1.5V
Z OUT
tPHL
tPLH VOH VOM VOM VOL
Figure 8. Driver Propagation Times
S1 0 OR 3V D OUT RL = 110 tPZH tPHZ 0.25V VOM IN 1.5V 1.5V
3V
0 GENERATOR (NOTE 4) CL = 50pF (NOTE 5) 50 OUT VOM = VOH + VOL 2
VOH
1.5V
0
Figure 9. Driver Enable and Disable Times (tPZH, tPSH, tPHZ)
VCC 3V RL = 110 S1 0 OR 3V D CL = 50pF (NOTE 5) GENERATOR (NOTE 4) OUT 50 VOM 0.25V VOL OUT tPSL tPLZ VCC IN 1.5V 1.5V 0
Figure 10. Driver Enable and Disable Times (tPZL, tPSL, tPLZ)
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9
3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
3.0V GENERATOR (NOTE 4) VID 50 R OUT IN CL = 15pF (NOTE 5) tRPLH tRPHL VCC 1.5V 0 VOM = VCC 2 OUT VOM VOM 0 1.5V 1.5V 0
Figure 11. Receiver Propagation Delay
1.5V -1.5V
S3 1k VID R
S1 VCC S2
CL (NOTE 5) GENERATOR (NOTE 4) 50
3V IN tPRZH tPRSH VOH OUT 1.5V 0 OUT 1.5V 1.5V 0 S1 OPEN S2 CLOSED S3 = 1.5V IN tPRZL tPRSL 1.5V
3V S1 CLOSED S2 OPEN S3 = -1.5V
0
VCC
VOL
3V IN 1.5V 0 tPRHZ OUT 0.25V VOH OUT 0 0.25V S1 OPEN S2 CLOSED S3 = 1.5V IN 1.5V
3V S1 CLOSED S2 OPEN S3 = -1.5V
0 tPRLZ VCC
VOL
Figure 12. Receiver Enable and Disable Times
Note 4: The input pulse is supplied by a generator with the following characteristics: f = 250kHz, 50% duty cycle, t r 6.0ns, ZO = 50. Note 5: CL includes probe and stray capacitance.
10
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
_____________________Function Tables
Devices with Receiver/Driver Enable (MAX3483E/MAX3485E/MAX3486E/MAX3491E)
___________Applications Information
The MAX3483E/MAX3485E/MAX3486E/MAX3488E/ MAX3490E/MAX3491E are low-power transceivers for RS-485 and RS-422 communications. The MAX3483E and MAX3488E can transmit and receive at data rates up to 250kbps, the MAX3486E at up to 2.5Mbps, and the MAX3485E/MAX3490E/MAX3491E at up to 12Mbps. The MAX3488E/MAX3490E/MAX3491E are full-duplex transceivers, while the MAX3483E/MAX3485E/MAX3486E are half-duplex. Driver Enable (DE) and Receiver Enable (RE) pins are included on the MAX3483E/MAX3485E/ MAX3486E/MAX3491E. When disabled, the driver and receiver outputs are high impedance.
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
Table 1. Transmitting
INPUTS RE X X 0 1 DE 1 1 0 0 DI 1 0 X X OUTPUTS B* 0 1 High-Z High-Z A* 1 0 High-Z High-Z MODE Normal Normal Normal Shutdown
* B and A outputs are Z and Y, respectively, for full-duplex part (MAX3491E). X = Don't care; High-Z = High impedance
Reduced EMI and Reflections (MAX3483E/MAX3486E/MAX3488E)
The MAX3483E/MAX3488E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 13 shows the driver output waveform of a MAX3485E/MAX3490E/MAX3491E transmitting a 125kHz signal, as well as the Fourier analysis of that waveform. High-frequency harmonics with large amplitudes are evident. Figure 14 shows the same information, but for the slew-rate-limited MAX3483E/MAX3488E transmitting the same signal. The high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.
Table 2. Receiving
INPUTS RE 0 0 0 1 DE 0* 0* 0* 0 A, B +0.2V -0.2V Inputs Open X OUTPUTS RO 1 0 1 High-Z MODE Normal Normal Normal Shutdown
* DE is a "don't care" (x) for the full-duplex part (MAX3491E). X = Don't care; High-Z = High impedance
Low-Power Shutdown Mode (MAX3483E/MAX3485E/MAX3486E/MAX3491E)
A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled (high impedance). In shutdown, the devices typically draw only 2nA of supply current. For these devices, the t PSH and t PSL enable times assume the part was in the low-power shutdown mode; the tPZH and tPZL enable times assume the receiver or driver was disabled, but the part was not shut down.
Devices without Receiver/Driver Enable (MAX3488E/MAX3490E)
Table 3. Transmitting
INPUT DI 1 0 OUTPUTS Z 0 1 Y 1 0
Table 4. Receiving
INPUTS A, B +0.2V -0.2V Inputs Open OUTPUT RO 1 0 1
10dB/div
10dB/div
0
500kHz/div
5MHz
0
500kHz/div
5MHz
Figure 13. Driver Output Waveform and FFT Plot of MAX3485E/ MAX3490E/MAX3491E Transmitting a 125kHz Signal
Figure 14. Driver Output Waveform and FFT Plot of MAX3483E/ MAX3488E Transmitting a 125kHz Signal
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
B 1V/div DI 2V/div Z 1V/div A 1V/div
Y 1V/div 20ns/div
RO 2V/div 20ns/div
Figure 15. MAX3485E/MAX3490E/MAX3491E Driver Propagation Delay
Figure 16. MAX3485E/MAX3490E/MAX3491E Receiver Propagation Delay Driven by External RS-485 Device
B 1V/div DI 2V/div Z 1V/div Y 1V/div 1s/div A 1V/div
RO 2V/div 1s/div
Figure 17. MAX3483E/MAX3488E Driver Propagation Delay
Figure 18. MAX3483E/MAX3488E Receiver Propagation Delay
DI 5V/div VY - VZ 2V/div
DI 5V/div VY - VZ 2V/div
RO 5V/div
RO 5V/div
2s/div
2s/div
Figure 19. MAX3483E/MAX3488E System Differential Voltage at 125kHz Driving 4000 Feet of Cable
Figure 20. MAX3485E/MAX3490E/MAX3491E System Differential Voltage at 125kHz Driving 4000 Feet of Cable
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
Driver-Output Protection
Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). In addition, a thermal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.
15kV ESD Protection
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 MAX3483E family of devices have extra protection against static electricity. Maxim's engineers have developed state-ofthe-art structures to protect these pins against ESD of 15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, Maxim's E versions keep working without latchup or damage. ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to the following limits: 1) 15kV using the Human Body Model 2) 8kV using the Contact-Discharge method specified in IEC 1000-4-2 3) 15kV using IEC 1000-4-2's Air-Gap method.
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
Propagation Delay
Figures 15-18 show the typical propagation delays. Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle). The receiver skew time, |tPRLH - tPRHL|, is under 10ns (20ns for the MAX3483E/MAX3488E). The driver skew times are 8ns for the MAX3485E/MAX3490E/MAX3491E, 12ns for the MAX3486E, and typically under 50ns for the MAX3483E/MAX3488E.
Line Length vs. Data Rate
The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 21 for an example of a line repeater. Figures 19 and 20 show the system differential voltage for parts driving 4000 feet of 26AWG twisted-pair wire at 125kHz into 120 loads. For faster data rate transmission, please consult the factory.
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 22a shows the Human Body Model and Figure 22b 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 1.5k resistor. IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX3483E family of devices helps you design equipment that meets Level 4 (the highest level) of IEC 1000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 1000-4-2 is higher peak current in IEC 1000-4-2, because series resistance is lower in the IEC 1000-4-2 model. Hence, the ESD withstand voltage measured to IEC 1000-4-2 is generally lower than that measured using the Human Body Model. Figure 23a shows the IEC 1000-4-2 model, and Figure 23b shows the current waveform for the 8kV IEC 1000-4-2, Level 4 ESD contact-discharge test.
MAX3488E MAX3490E MAX3491E
A RO RE DE DI
R
120 B
DATA IN
Z
D
120 Y
DATA OUT
NOTE: RE AND DE ON MAX3491E ONLY.
Figure 21. Line Repeater for MAX3488E/MAX3490E/MAX3491E
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
RC 1M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST IP 100% 90% AMPERES Cs 100pF STORAGE CAPACITOR 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
Figure 22a. Human Body ESD Test Model
Figure 22b. Human Body Current Waveform
RC 50M to 100M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE
RD 330 DISCHARGE RESISTANCE DEVICE UNDER TEST
I 100% 90%
Cs 150pF
STORAGE CAPACITOR
I PEAK
10%
Figure 23a. IEC 1000-4-2 ESD Test Model
t r = 0.7ns to 1ns t 30ns 60ns
Figure 23b. IEC 1000-4-2 ESD Generator Current Waveform
The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized.
Typical Applications
The MAX3483E/MAX3485E/MAX3486E/MAX3488E/ MAX3490E/MAX3491E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 24 and 25 show typical network applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 21. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited MAX3483E/MAX3488E and the partially slew-rate-limited MAX3486E are more tolerant of imperfect termination.
Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. Of course, all pins require this protection, not just RS-485 inputs and outputs.
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
120 DI B 120 B DE
D
DE RO RE A B A B A A
D
DI
R R R D
R
RO RE
MAX3483E MAX3485E MAX3486E
DI
D
DE
RO RE
DI
DE
RO RE
Figure 24. MAX3483E/MAX3485E/MAX3486E Typical RS-485 Network
A RO RE DE Z DI
Y 120 120 Z DE B 120 120 Y Z B A Y Z B A A RE RO
R
B
D
DI
D
Y
R
R D D
R
MAX3488E MAX3490E MAX3491E
DE RE RO
DI
DE RE RO
DI
NOTE: RE AND DE ON MAX3491E ONLY.
Figure 25. MAX3488E/MAX3490E/MAX3491E Full-Duplex RS-485 Network
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3.3V-Powered, 15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers
MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E
Ordering Information (continued)
PART MAX3486ECSA MAX3486ECPA MAX3486EESA MAX3486EEPA MAX3488ECSA MAX3488ECPA MAX3488EESA MAX3488EEPA MAX3490ECSA MAX3490ECPA MAX3490EESA MAX3490EEPA MAX3491ECSD MAX3491ECPD MAX3491EESD MAX3491EEPD TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 14 SO 14 Plastic DIP 14 SO 14 Plastic DIP
Chip Information
TRANSISTOR COUNT: 761
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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