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MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
General Description
The MAX3483, MAX3485, MAX3486, MAX3488,
MAX3490, and MAX3491 are 3.3V, low-power transceivers for
RS-485 and RS-422 communication. Each part contains
one driver and one receiver. The MAX3483 and MAX3488
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 MAX3486
transmits up to 2.5Mbps. The MAX3485, MAX3490, and
MAX3491 transmit at up to 10Mbps.
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 MAX3488, MAX3490, and MAX3491 feature fullduplex communication, while the MAX3483, MAX3485, and
MAX3486 are designed for half-duplex communication.
Applications
●
●
●
●
Low-Power RS-485/RS-422 Transceivers
Telecommunications
Transceivers for EMI-Sensitive Applications
Industrial-Control Local Area Networks
Features
● Operate from a Single 3.3V Supply—
No Charge Pump!
● Interoperable with +5V Logic
● 8ns Max Skew (MAX3485/MAX3490/MAX3491)
● Slew-Rate Limited for Errorless Data Transmission
(MAX3483/MAX3488)
● 2nA Low-Current Shutdown Mode
(MAX3483/MAX3485/MAX3486/MAX3491)
● -7V to +12V Common-Mode Input Voltage Range
● Allows up to 32 Transceivers on the Bus
● Full-Duplex and Half-Duplex Versions Available
● Industry Standard 75176 Pinout
(MAX3483/MAX3485/MAX3486)
● Current-Limiting and Thermal Shutdown for Driver
Overload Protection
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX3483CPA
0°C to +70°C
8 Plastic DIP
MAX3483CSA
0°C to +70°C
8 SO
MAX3483C/D
0°C to +70°C
Dice*
MAX3483EPA
-40°C to +85°C
8 Plastic DIP
MAX3483ESA
-40°C to +85°C
8 SO
MAX3485CPA
0°C to +70°C
8 Plastic DIP
MAX3485CSA
0°C to +70°C
8 SO
MAX3485C/D
0°C to +70°C
Dice*
MAX3485EPA
-40°C to +85°C
8 Plastic DIP
MAX3485ESA
-40°C to +85°C
8 SO
Ordering Information continued at end of data sheet.
* Contact factory for for dice specifications.
Selection Table
PART
NUMBER
GUARANTEED
DATA RATE
(Mbps)
MAX3483
HALF/FULL
DUPLEX
SLEW-RATE
LIMITED
DRIVER/
RECEIVER
ENABLE
SHUTDOWN
CURRENT
(nA)
PIN
COUNT
0.25
Half
Yes
Yes
2
8
MAX3485
10
Half
No
Yes
2
8
MAX3486
2.5
Half
Yes
Yes
2
8
MAX3488
0.25
Full
Yes
No
—
8
MAX3490
10
Full
No
No
—
8
MAX3491
10
Full
No
Yes
2
14
19-0333; Rev 1; 5/19
SUPPLY
VOLTAGE
(V)
3.0 to 3.6
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
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 = +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)...727mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
14-Pin Plastic DIP (derate 10mW/°C above +70°C)....800mW
14-Pin SO (derate 8.33mW/°C above +70°C)..............667mW
Operating Temperature Ranges
MAX34_ _C_ _....................................................0°C to +70°C
MAX34_ _E_ _................................................ -40°C to +85°C
Junction Temperature.......................................................+160°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Package Information
14 SOIC
PACKAGE CODE
S14+1
Outline Number
21-0041
Land Pattern Number
90-0112
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θJA)
120
Junction to Case (θJA)
37
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
84
Junction to Case (θJA)
34
For the latest package outline information and land patterns (footprints), 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.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board.
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
www.maximintegrated.com
Maxim Integrated │ 2
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
DC Electrical Characteristics
(VCC = 3.3V ±0.3V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C)
PARAMETER
Differential Driver Output
SYMBOL
VOD
CONDITIONS
MIN
RL = 100Ω (RS-422), Figure 4
2.0
RL = 54Ω (RS-485), Figure 4
1.5
RL = 60Ω (RS-485), VCC = 3.3V, Figure 5
1.5
TYP
MAX
UNITS
V
Change in Magnitude of Driver
Differential Output Voltage for
Complementary Output States
(Note 1)
ΔVOD
RL = 54Ω or 100Ω, Figure 4
0.2
V
Driver Common-Mode Output
Voltage
VOC
RL = 54Ω or 100Ω, Figure 4
3
V
ΔVOC
RL = 54Ω or 100Ω, Figure 4
0.2
V
Change in Magnitude of
Common-Mode Output Voltage
(Note 1)
Input High Voltage
VIH
DE, DI, RE
2.0
V
Input Low Voltage
VIL
DE, DI, RE
0.8
V
Logic Input Current
IIN1
DE, DI, RE
±2
μA
Input Current (A, B)
IIN2
DE = 0V,
VCC = 0V or 3.6V
VIN = 12V
1.0
VIN = -7V
-0.8
Output Leakage (Y, Z)
IO
DE = 0V, RE = 0V,
VCC = 0V or 3.6V, MAX3491
VOUT = 12V
20
VOUT = -7V
-20
Output Leakage (Y, Z)
in Shutdown Mode
IO
DE = 0V, RE = VCC,
VCC = 0V or 3.6V, MAX3491
VOUT = 12V
1
VOUT = -7V
-1
Receiver Differential
Threshold Voltage
VTH
-7V ≤ VCM ≤ 12V
-0.2
0.2
μA
μA
V
Receiver Input Hysteresis
ΔVTH
VCM = 0V
Receiver Output High Voltage
VOH
IOUT = -1.5mA, VID = 200mV, Figure 6
Receiver Output Low Voltage
VOL
IOUT = 2.5mA, VID = 200mV, Figure 6
0.4
V
Three-State (High Impedance)
Output Current at Receiver
IOZR
VCC = 3.6V, 0V ≤ VOUT ≤ VCC
±1
μA
Receiver Input Resistance
RIN
-7V ≤ VCM ≤ 12V
ICC
No load,
DI = 0V or VCC
Supply Current
Supply Current in Shutdown
Mode
ISHDN
Driver Short-Circuit Output
Current
IOSD
Receiver Short-Circuit Output
Current
IOSR
www.maximintegrated.com
50
mA
mV
VCC - 0.4
V
12
kΩ
DE = VCC,
RE = 0V or VCC
1.1
2.2
DE = 0V,
RE = 0V
0.95
1.9
0.002
1
mA
DE = 0V, RE = VCC, DI = VCC or 0V
VOUT = -7V
-250
VOUT = 12V
250
0V ≤ VRO ≤ VCC
±8
±60
µA
mA
mA
Maxim Integrated │ 3
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Driver Switching Characteristics—MAX3485, MAX3490, and MAX3491
(VCC = 3.3V, TA = +25°C)
MIN
TYP
MAX
UNITS
Driver Differential Output Delay
PARAMETER
SYMBOL
tDD
RL = 60Ω, Figure 7
CONDITIONS
1
22
35
ns
Driver Differential Output Transition Time
tTD
RL = 60Ω, Figure 7
3
8
25
ns
Driver Propagation Delay, Low-to-High Level
tPLH
RL = 27Ω, Figure 8
7
22
35
ns
Driver Propagation Delay, High-to-Low Level
tPHL
RL = 27Ω, Figure 8
7
22
35
ns
|tPLH - tPHL| Driver Propagation Delay Skew (Note 2)
tPDS
RL = 27Ω, Figure 8
8
ns
DRIVER OUTPUT ENABLE/DISABLE TIMES (MAX3485/MAX3491 only)
Driver Output Enable Time to Low Level
tPZL
RL = 110Ω, Figure 10
45
90
ns
Driver Output Enable Time to High Level
tPZH
RL = 110Ω, Figure 9
45
90
ns
Driver Output Disable Time from High Level
tPHZ
RL = 110Ω, Figure 9
40
80
ns
Driver Output Disable Time from Low Level
tPLZ
RL = 110Ω, Figure 10
40
80
ns
Driver Output Enable Time from Shutdown to Low Level
tPSL
RL = 110Ω, Figure 10
650
900
ns
Driver Output Enable Time from Shutdown to High Level
tPSH
RL = 110Ω, Figure 9
650
900
ns
MIN
TYP
MAX
UNITS
Driver Switching Characteristics—MAX3486
(VCC = 3.3V, TA = +25°C)
PARAMETER
SYMBOL
CONDITIONS
Driver Differential Output Delay
tDD
RL = 60Ω, Figure 7
24
48
70
ns
Driver Differential Output Transition Time
tTD
RL = 60Ω, Figure 7
15
35
60
ns
Driver Propagation Delay, Low-to-High Level
tPLH
RL = 27Ω, Figure 8
20
48
70
ns
Driver Propagation Delay, High-to-Low Level
tPHL
RL = 27Ω, Figure 8
20
48
70
ns
|tPLH - tPHL| Driver Propagation Delay Skew (Note 2)
tPDS
RL = 27Ω, Figure 8
11
ns
Driver Output Enable Time to Low Level
tPZL
RL = 110Ω, Figure 10
55
100
ns
Driver Output Enable Time to High Level
tPZH
RL = 110Ω, Figure 9
55
100
ns
Driver Output Disable Time from High Level
tPHZ
RL = 110Ω, Figure 9
45
80
ns
Driver Output Disable Time from Low Level
tPLZ
RL = 110Ω, Figure 10
45
80
ns
Driver Output Enable Time from Shutdown to Low Level
tPSL
RL = 110Ω, Figure 10
700
1000
ns
Driver Output Enable Time from Shutdown to High Level
tPSH
RL = 110Ω, Figure 9
700
1000
ns
www.maximintegrated.com
Maxim Integrated │ 4
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Driver Switching Characteristics—MAX3483 and MAX3488
(VCC = 3.3V, TA = +25°C)
MIN
TYP
MAX
UNITS
Driver Differential Output Delay
PARAMETER
SYMBOL
tDD
RL = 60Ω, Figure 7
CONDITIONS
600
900
1400
ns
Driver Differential Output Transition Time
tTD
RL = 60Ω, Figure 7
400
700
1200
ns
Driver Propagation Delay, Low-to-High Level
tPLH
RL = 27Ω, Figure 8
700
1000
1500
ns
Driver Propagation Delay, High-to-Low Level
tPHL
RL = 27Ω, Figure 8
700
1000
1500
ns
|tPLH - tPHL| Driver Propagation Delay Skew (Note 2)
tPDS
RL = 27Ω, Figure 8
100
ns
DRIVER OUTPUT ENABLE/DISABLE TIMES (MAX3485/MAX3491 only)
Driver Output Enable Time to Low Level
tPZL
RL = 110Ω, Figure 10
900
1300
ns
Driver Output Enable Time to High Level
tPZH
RL = 110Ω, Figure 9
600
800
ns
Driver Output Disable Time from High Level
tPHZ
RL = 110Ω, Figure 9
50
80
ns
Driver Output Disable Time from Low Level
tPLZ
RL = 110Ω, Figure 10
50
80
ns
Driver Output Enable Time from Shutdown to Low Level
tPSL
RL = 110Ω, Figure 10
1.9
2.7
ns
Driver Output Enable Time from Shutdown to High Level
tPSH
RL = 110Ω, Figure 9
2.2
3.0
ns
Receiver Switching Characteristics
(VCC = 3.3V, TA = +25°C)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Time to Shutdown
tSHDN
MAX3483/MAX3485/MAX3486/MAX3491 only
(Note 3)
80
190
300
ns
Receiver Propagation Delay,
Low-to-High Level
tRPLH
VID = 0V to 3.0V, CL = 15pF, Figure 11
25
65
90
MAX3483/MAX3488
25
75
120
Receiver Propagation Delay,
High-to-Low Level
tRPHL
VID = 0V to 3.0V, CL = 15pF, Figure 11
25
65
90
MAX3483/MAX3488
25
75
120
|tPLH - tPHL| Receiver
Propagation Delay Skew
tRPDS
Receiver Output Enable Time
to Low Level
tPRZL
CL = 15pF, Figure 12,
MAX3483/MAX3485/MAX3486/MAX3491 only
25
50
ns
Receiver Output Enable Time
to High Level
tPRZH
CL = 15pF, Figure 12,
MAX3483/MAX3485/MAX3486/MAX3491 only
25
50
ns
Receiver Output Disable
Time from High Level
tPRHZ
CL = 15pF, Figure 12,
MAX3483/MAX3485/MAX3486/MAX3491 only
25
45
ns
Receiver Output Disable
Time from Low Level
tPRLZ
CL = 15pF, Figure 12,
MAX3483/MAX3485/MAX3486/MAX3491 only
25
45
ns
Receiver Output Enable Time
from Shutdown to Low Level
tPRSL
CL = 15pF, Figure 12,
MAX3483/MAX3485/MAX3486/MAX3491 only
720
1400
ns
Receiver Output Enable Time
from Shutdown to High Level
tPRSH
CL = 15pF, Figure 12,
MAX3483/MAX3485/MAX3486/MAX3491 only
720
1400
ns
VID = 0V to 3.0V, CL = 15pF, Figure 11
10
MAX3483/MAX3488
20
ns
ns
ns
Note 1: ΔVOD and ΔVOC 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 parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the parts are guaranteed to
have entered shutdown. See Low-Power Shutdown Mode section.
www.maximintegrated.com
Maxim Integrated │ 5
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
15
10
-16
-14
-12
-10
-8
-6
-4
5
3.30
0.5
1.0
1.5
2.0
2.5
0
3.5
3.10
0
0.5
1.0
1.5
2.0
2.5
3.0
3.00
3.5
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
DRIVER OUTPUT CURRENT vs.
DIFFERENTIAL OUTPUT VOLTAGE
DRIVER DIFFERENTIAL OUTPUT
VOLTAGE vs.TEMPERATURE
OUTPUT CURRENT (mA)
0.6
90
0.5
0.4
0.3
0.2
80
70
60
50
40
30
20
0.1
10
0
20
40
60
80
0
100
0
0.5
TEMPERATURE (°C)
1.0
1.5
2.0
2.5
3.0
3.5
DIFFERENTIAL OUTPUT VOLTAGE (V)
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
-40
-20
0
20
40
-100
MAX3483-07
125
100
75
50
60
80
100
-80
-60
-40
-20
25
0
2.4
OUTPUT CURRENT vs.
DRIVER OUTPUT HIGH VOLTAGE
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
150
R = 54Ω
2.5
TEMPERATURE (°C)
OUTPUT CURRENT vs.
DRIVER OUTPUT LOW VOLTAGE
175
100
MAX3483-08
-20
2.6
DIFFERENTIAL OUTPUT VOLTAGE (V)
100
MAX3483-05
IRO = 2.5mA
-40
3.15
OUTPUT HIGH VOLTAGE (V)
0.7
0
3.20
OUTPUT LOW VOLTAGE (V)
0.8
OUTPUT LOW VOLTAGE (V)
3.0
MAX3483-04
0
3.25
3.05
-2
0
IRO = 1.5mA
MAX3483-03
-18
OUTPUT HIGH VOLTAGE (V)
20
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
MAX3483-02
MAX3483-01
-20
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
25
OUTPUT CURRENT vs.
RECEIVER OUTPUT HIGH VOLTAGE
MAX3483-06
OUTPUT CURRENT vs.
RECEIVER OUTPUT LOW VOLTAGE
0
2
4
6
8
OUTPUT LOW VOLTAGE (V)
www.maximintegrated.com
10
12
0
-7 -6 -5 -4 -3 -2 -1 0 1 2 3
OUTPUT HIGH VOLTAGE (V)
4
5
Maxim Integrated │ 6
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Typical Operating Characteristics (continued)
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
90
1.1
DE = VCC, RE = X
1.0
DE = 0, RE = 0
0.9
MAX3483-10
100
MAX3483-09
X = DON’T CARE
SHUTDOWN CURRENT (nA)
SUPPLY CURRENT (mA)
1.2
SHUTDOWN CURRENT
vs. TEMPERATURE
0.8
80
70
60
50
40
30
20
10
0.7
-40
-20
0
20
40
60
80
0
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Pin Description
PIN
MAX3483/
MAX3485/
MAX3486
MAX3488/
MAX3490
MAX3491
1
2
2
RO
Receiver Output. If A > B by 200mV, RO will be high; if A < B by
200mV, RO will be low.
2
—
3
RE
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.
NAME
FUNCTION
3
—
4
DE
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.
4
3
5
DI
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.
5
4
6, 7
GND
—
5
9
Y
Noninverting Driver Output
—
6
10
Z
Inverting Driver Output
Ground
6
—
—
A
Noninverting Receiver Input and Noninverting Driver Output
—
8
12
A
Noninverting Receiver Input
7
—
—
B
Inverting Receiver Input and Inverting Driver Output
—
7
11
B
Inverting Receiver Input
8
1
13, 14
VCC
Positive Supply: 3.0V ≤ VCC ≤ 3.6V
—
—
1, 8
N.C.
No Connect—not internally connected
www.maximintegrated.com
Maxim Integrated │ 7
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
TOP VIEW
R
VCC
RO
RE 2
7
B
RE 2
DE 3
6
A
DE 3
5
GND
DI 4
D
R
1
8
1
RO
DI 4
MAX3483
MAX3485
MAX3486
8 VCC
7 B
Rt
6
A
5 GND
D
DE
D
B
Rt
A
DI
RO
R
RE
DIP/SO
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH.
Figure 1. MAX3483/MAX3485/MAX3486 Pin Configuration and Typical Operating Circuit
TOP VIEW
VCC
8
A
RO 2
7
B
DI 3
6
Z
5
Y
VCC 1
GND 4
R
D
DI
RO
3
5 Y
D
Rt
6 Z
8 A
2
VCC
MAX3488
MAX3490
1
R
7
R
RO
Rt
D
DI
B
DIP/SO
4
GND
GND
Figure 2. MAX3488/MAX3490 Pin Configuration and Typical Operating Circuit
TOP VIEW
DE
4
N.C.
1
RO
2
RE
3
12 A
DE
4
11 B
DI
5
10 Z
GND
6
GND
7
VCC
13, 14
14 V CC
R
D
DIP/SO
13 V CC
9
Y
8
N.C.
DI
RO
N.C.
5
9
D
10
12
2
R
11
1, 8
3
VCC RE
MAX3491
Y
Rt
R
RO
Z
A
Rt
D
DI
B
6, 7
RE GND
GND
DE
Figure 3. MAX3491 Pin Configuration and Typical Operating Circuit
www.maximintegrated.com
Maxim Integrated │ 8
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
375Ω
RL
2
VOD
D
RL
VCC
2
D
VOC
VCC
Figure 4. Driver VOD and VOC
VID
VCM =
-7V to +12V
RL
VOD
375Ω
Figure 5. Driver VOD with Varying Common-Mode Voltage
R
0V
VOL
IOL
(+)
VOH
IOH
(-)
Figure 6. Receiver VOH and VOL
3V
IN
1.5V
1.5V
CL
D
GENERATOR
(NOTE 4)
0V
RL =
60Ω
OUT
tDO
50Ω
VCC
OUT
CL
CL = 15pF (NOTE 5)
50%
10%
tTD
tDO
90%
90%
≈ 2.0V
50%
10%
≈ -2.0V
tTD
Figure 7. Driver Differential Output Delay and Transition Times
www.maximintegrated.com
Maxim Integrated │ 9
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
3V
VOM
IN
1.5V
1.5V
RL = 27Ω
0V
S1
GENERATOR
(NOTE 4)
tPLH
OUT
D
50Ω
CL = 15pF
(NOTE 5)
VCC
VOM =
VOH + VOL
2
tPHL
VOH
Y
OUT
VOM
VOM
VOL
tPHL
≈ 1.5V
tPLH
VOH
Z
OUT
VOM
VOM
VOL
Figure 8. Driver Propagation Times
3V
S1
0V OR 3V
GENERATOR
(NOTE 4)
OUT
D
IN
0V
RL = 110Ω
CL = 50pF
(NOTE 5)
1.5V
1.5V
tPZH
tPHZ
50Ω
OUT
VOM =
VOH + VOL
2
0.25V
VOM
≈ 1.5V
VOH
0V
Figure 9. Driver Enable and Disable Times (tPZH, tPSH, tPHZ)
VCC
S1
0V OR 3V
3V
RL = 110Ω
IN
1.5V
1.5V
0V
OUT
D
tPSL
GENERATOR
(NOTE 4)
CL = 50pF
(NOTE 5)
50Ω
tPLZ
VCC
OUT
VOM
0.25V
VOL
Figure 10. Driver Enable and Disable Times (tPZL, tPSL, tPLZ)
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Maxim Integrated │ 10
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
VID
GENERATOR
(NOTE 4)
3.0V
OUT
R
IN
50Ω
CL = 15pF
(NOTE 5)
1.5V
1.5V
0V
tRPLH
tRPHL
VCC
1.5V
VOM =
0V
VOM
OUT
VCC
2
VOM
0V
Figure 11. Receiver Propagation Delay
S1
S3
1.5V
-1.5V
VID
GENERATOR
(NOTE 4)
R
50Ω
1.5V
0V
tPRZH
tPRSH
OUT
S2
CL
(NOTE 5)
3V
IN
VCC
1k
S1 OPEN
S2 CLOSED
S3 = 1.5V
3V
IN
1.5V
0V
tPRZL
tPRSL
VOH
OUT
1.5V
IN
1.5V
0V
VCC
1.5V
0V
3V
S1 CLOSED
S2 OPEN
S3 = -1.5V
VOL
S1 OPEN
S2 CLOSED
S3 = 1.5V
3V
IN
1.5V
0V
S1 CLOSED
S2 OPEN
S3 = -1.5V
tPRHZ
OUT 0.25V
tPRLZ
VOH
OUT
0V
VCC
0.25V
VOL
Figure 12. Receiver Enable and Disable Times
Note 4: The input pulse is supplied by a generator with the following characteristics: PRR = 250kHz, 50% duty cycle, tr ≤ 6.0ns, ZO = 50Ω.
Note 5: CL includes probe and stray capacitance.
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Maxim Integrated │ 11
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Function Tables
Applications Information
Devices with Receiver/Driver Enable
(MAX3483/MAX3485/MAX3486/MAX3491)
Table 1. Transmitting
RE
INPUTS
OUTPUTS
MODE
DE
DI
B*
A*
X
1
1
0
1
Normal
X
1
0
1
0
Normal
0
0
X
High-Z
High-Z
Normal
1
0
X
High-Z
High-Z
Shutdown
* B and A outputs are Z and Y, respectively, for full-duplex part
(MAX3491).
X = Don’t care; High-Z = High impedance
Table 2. Receiving
INPUTS
OUTPUTS
MODE
RE
DE
A, B
B*
0
0*
≥ +0.2V
1
Normal
0
0*
≤ -0.2V
0
Normal
0
0*
Inputs Open
1
Normal
1
0
X
High-Z
Shutdown
* DE is a “don’t care” (x) for the full-duplex part (MAX3491).
X = Don’t care; High-Z = High impedance
Devices without Receiver/Driver Enable
(MAX3488/MAX3490)
Table 3. Transmitting
INPUT
Table 4. Receiving
INPUTS
OUTPUT
DI
Z
OUTPUTS
Y
A, B
RO
1
0
1
≥ +0.2V
1
0
1
0
≤ -0.2V
0
Inputs Open
1
500kHz/div
5MHz
Figure 13. Driver Output Waveform and FFT Plot of MAX3485/
MAX3490/MAX3491 Transmitting a 125kHz Signal
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Reduced EMI and Reflections
(MAX3483/MAX3486/MAX3488)
The MAX3483/MAX3488 are slew-rate limited, minimizing
EMI and reducing reflections caused by improperly
terminated cables. Figure 13 shows both the driver output
waveform of a MAX3485/MAX3490/MAX3491 transmitting
a 125kHz signal and 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 MAX3483/MAX3488 transmitting the
same signal. The high-frequency harmonics have much
lower amplitudes, and the potential for EMI is significantly
reduced.
Low-Power Shutdown Mode
(MAX3483/MAX3485/MAX3486/MAX3491)
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 tPSH and tPSL 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.
10dB/div
10dB/div
0Hz
The MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/
MAX3491 are low-power transceivers for RS-485 and
RS-422 communications. The MAX3483 and MAX3488
can transmit and receive at data rates up to 250kbps, the
MAX3486 at up to 2.5Mbps, and the MAX3485/MAX3490/
MAX3491 at up to 10Mbps. The MAX3488/MAX3490/
MAX3491 are full-duplex transceivers, while the MAX3483/
MAX3485/MAX3486 are half-duplex. Driver Enable (DE)
and Receiver Enable (RE) pins are included on the
MAX3483/MAX3485/MAX3486/MAX3491. When disabled,
the driver and receiver outputs are high impedance.
0Hz
500kHz/div
5MHz
Figure 14. Driver Output Waveform and FFT Plot of MAX3483/
MAX3488 Transmitting a 125kHz Signal
Maxim Integrated │ 12
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
B
1V/div
DI
2V/div
A
1V/div
Z
1V/div
RO
2V/div
Y
1V/div
20ns/div
20ns/div
Figure 15. MAX3485/MAX3490/MAX3491 Driver Propagation
Delay
Figure 16. MAX3485/MAX3490/MAX3491 Receiver
Propagation Delay Driven by External RS-485 Device
B
1V/div
DI
2V/div
A
1V/div
Z
1V/div
Y
1V/div
RO
2V/div
1ms/div
1ms/div
Figure 17. MAX3483/MAX3488 Driver Propagation Delay
Figure 18. MAX3483/MAX3488 Receiver Propagation Delay
DI
5V/div
DI
5V/div
VY - VZ
2V/div
VY - VZ
2V/div
RO
5V/div
RO
5V/div
2µs/div
Figure 19. MAX3483/MAX3488 System Differential Voltage at
125kHz Driving 4000 ft of Cable
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2ms/div
Figure 20. MAX3485/MAX3490/MAX3491 System Differential
Voltage at 125kHz Driving 4000 ft of Cable
Maxim Integrated │ 13
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
120Ω
DI
DE
B
D
D
DE
RO
RE
120Ω
B
A
B
A
B
A
DI
A
R
R
RO
RE
R
R
D
D
MAX3483
MAX3485
MAX3486
DI
DE
RO RE
DI
DE
RO RE
Figure 21. MAX3483/MAX3485/MAX3486 Typical RS-485 Network
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.
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 MAX3483/MAX3488). The driver skew
times are 8ns for the MAX3485/MAX3490/MAX3491,
11ns for the MAX3486, and typically under 100ns for the
MAX3483/MAX3488.
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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 23.
Figures 19 and 20 show the system differential voltage
for parts driving 4000 feet of 26AWG twisted-pair wire at
125kHz into 120Ω loads.
Typical Applications
The MAX3483, MAX3485, MAX3486, MAX3488,
MAX3490, and MAX3491 transceivers are designed
for bidirectional data communications on multipoint bus
transmission lines. Figures 21 and 22 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 23.
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 MAX3483/MAX3488 and the
partially slew-rate-limited MAX3486 are more tolerant of
imperfect termination.
Maxim Integrated │ 14
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
A
R
RO
RE
DE
Y
120Ω
120Ω
D
B
Z
Z
B
D
DI
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
120Ω
120Ω
Y
Z
Y
B
A
Y
Z
R
A
DE RERO
DE
RE
RO
R
A
R
MAX3488
MAX3490
MAX3491
D
D
DI
B
DI
DI
DE RERO
NOTE: RE AND DE ON MAX3491 ONLY.
Figure 22. MAX3488/MAX3490/MAX3491 Full-Duplex RS-485 Network
A
RO
RE
R
B
MAX3488
MAX3490
MAX3491
120Ω
DATA IN
DE
DI
Z
D
Y
120Ω
DATA OUT
NOTE: RE AND DE ON MAX3491 ONLY.
Figure 23. Line Repeater for MAX3488/MAX3490/MAX3491
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Maxim Integrated │ 15
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Ordering Information (continued)
MAX3486CPA
0°C to +70°C
8 Plastic DIP
MAX3486CSA
0°C to +70°C
8 SO
MAX3486C/D
0°C to +70°C
Dice*
MAX3486EPA
-40°C to +85°C
8 Plastic DIP
MAX3486ESA
-40°C to +85°C
8 SO
MAX3488CPA
0°C to +70°C
8 Plastic DIP
MAX3488CSA
0°C to +70°C
8 SO
MAX3488C/D
0°C to +70°C
Dice*
MAX3488EPA
-40°C to +85°C
8 Plastic DIP
MAX3488ESA
-40°C to +85°C
8 SO
MAX3490CPA
0°C to +70°C
8 Plastic DIP
MAX3490CSA
0°C to +70°C
8 SO
MAX3490C/D
0°C to +70°C
Dice*
MAX3490EPA
-40°C to +85°C
8 Plastic DIP
MAX3490ESA
-40°C to +85°C
8 SO
MAX3491CPD
0°C to +70°C
14 Plastic DIP
MAX3491CSD
0°C to +70°C
14 SO
MAX3491C/D
0°C to +70°C
Dice*
MAX3491EPD
-40°C to +85°C
MAX3491ESD
-40°C to +85°C
* Contact factory for for dice specifications.
Chip Topography
V CC
RO
A
RE
B
Z/B
0.146"
(3.71mm)
DE
DI
Y/A
14 Plastic DIP
14 SO
GND
GND
0.086"
(2.18mm)
TRANSISTOR COUNT: 810
SUBSTRATE CONNECTED TO GROUND
www.maximintegrated.com
Maxim Integrated │ 16
MAX3483/MAX3485/
MAX3486/MAX3488/
MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
12/94
Initial release
1
5/19
Updated Absolute Maximum Ratings and Selection table, added Package
Information section
DESCRIPTION
—
1, 2
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
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 specifications 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.
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