Maxim MAX3491 3.3v-powered, 10mbps and slew-rate-limited true rs-485/rs-422 transceiver Datasheet

19-0333; Rev 0; 12/94
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
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.
____________________________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
________________________Applications
Low-Power RS-485/RS-422 Transceivers
Telecommunications
Transceivers for EMI-Sensitive Applications
Industrial-Control Local Area Networks
PART
TEMP. RANGE
MAX3483CPA
0°C to +70°C
8 Plastic DIP
PIN-PACKAGE
MAX3483CSA
MAX3483C/D
MAX3483EPA
MAX3483ESA
MAX3485CPA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 SO
Dice*
8 Plastic DIP
8 SO
8 Plastic DIP
MAX3485CSA
MAX3485C/D
MAX3485EPA
MAX3485ESA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
8 SO
Dice*
8 Plastic DIP
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
MAX3485
SUPPLY
VOLTAGE
(V)
HALF/FULL
DUPLEX
SLEW-RATE
LIMITED
DRIVER/
RECEIVER
ENABLE
SHUTDOWN
CURRENT
(nA)
PIN
COUNT
0.25
Half
Yes
Yes
2
8
10
Half
No
Yes
2
8
Half
Yes
Yes
2
8
Full
Yes
No
—
8
MAX3486
2.5
MAX3488
0.25
MAX3490
10
Full
No
No
—
8
MAX3491
10
Full
No
Yes
2
14
3.0 to 3.6
________________________________________________________________ Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
1
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
_______________General Description
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
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
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 = +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)
∆VOD
RL = 54Ω or 100Ω, Figure 4
0.2
V
Driver Common-Mode Output
Voltage
VOC
RL = 54Ω or 100Ω, Figure 4
3
V
∆VOC
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
Input Low Voltage
VIL
DE, DI, RE
2.0
0.8
V
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
VOUT = 12V
DE = 0V, RE = 0V,
VCC = 0V or 3.6V, MAX3491 VOUT = -7V
-20
Output Leakage (Y, Z)
in Shutdown Mode
IO
VOUT = 12V
DE = 0V, RE = VCC,
VCC = 0V or 3.6V, MAX3491 VOUT = -7V
-1
Receiver Differential
Threshold Voltage
VTH
-7V ≤ VCM ≤ 12V
20
1
-0.2
0.2
mA
µA
µA
V
Receiver Input Hysteresis
∆VTH
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
2
50
mV
VCC - 0.4
12
_______________________________________________________________________________________
V
kΩ
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.3V ±0.3V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C)
PARAMETER
Supply Current
SYMBOL
ICC
Supply Current in Shutdown Mode
ISHDN
Driver Short-Circuit Output
Current
IOSD
Receiver Short-Circuit Output
Current
IOSR
CONDITIONS
No load,
DI = 0V or VCC
MIN
TYP
MAX
DE = VCC,
RE = 0V or VCC
1.1
2.2
DE = 0V,
RE = 0V
0.95
mA
DE = 0V, RE = VCC, DI = VCC or 0V
0.002
1.9
1
VOUT = -7V
-250
VOUT = 12V
250
0V ≤ VRO ≤ VCC
UNITS
±8
±60
µA
mA
mA
DRIVER SWITCHING CHARACTERISTICS—MAX3485, MAX3490, and MAX3491
(VCC = 3.3V, TA = +25°C)
MIN
TYP
MAX
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
8
ns
tPDS
RL = 27Ω, Figure 8
|tPLH - tPHL| Driver Propagation Delay Skew (Note 2)
DRIVER OUTPUT ENABLE/DISABLE TIMES (MAX3485/MAX3491 only)
UNITS
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
DRIVER SWITCHING CHARACTERISTICS—MAX3486
(VCC = 3.3V, TA = +25°C)
MIN
TYP
MAX
Driver Differential Output Delay
PARAMETER
SYMBOL
tDD
RL = 60Ω, Figure 7
CONDITIONS
24
48
70
UNITS
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
|tPLH - tPHL| Driver Propagation Delay Skew (Note 2)
tPDS
RL = 27Ω, Figure 8
Driver Output Enable Time to Low Level
tPZL
RL = 110Ω, Figure 10
Driver Output Enable Time to High Level
tPZH
Driver Output Disable Time from High Level
Driver Output Disable Time from Low Level
70
ns
11
ns
55
100
ns
RL = 110Ω, Figure 9
55
100
ns
tPHZ
RL = 110Ω, Figure 9
45
80
ns
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
_______________________________________________________________________________________
3
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
Driver Differential Output Delay
PARAMETER
SYMBOL
tDD
RL = 60Ω, Figure 7
CONDITIONS
600
900
MAX
1400
UNITS
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
tPDS
|tPLH - tPHL| Driver Propagation Delay Skew (Note 2)
DRIVER OUTPUT ENABLE/DISABLE TIMES (MAX3483 only)
RL = 27Ω, Figure 8
100
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
µs
Driver Output Enable Time from Shutdown to High Level
tPSH
RL = 110Ω, Figure 9
2.2
3.0
µs
MIN
TYP
MAX
MAX3483/MAX3485/MAX3486/MAX3491 only
(Note 3)
80
190
300
VID = 0V to 3.0V, CL = 15pF, Figure 11
25
65
90
MAX3483/MAX3488
25
75
120
VID = 0V to 3.0V, CL = 15pF, Figure 11
25
65
90
MAX3483/MAX3488
25
75
120
ns
RECEIVER SWITCHING CHARACTERISTICS
(VCC = 3.3V, TA = +25°C)
PARAMETER
SYMBOL
CONDITIONS
UNITS
Time to Shutdown
tSHDN
Receiver Propagation Delay,
Low-to-High Level
tRPLH
Receiver Propagation Delay,
High-to-Low Level
tRPHL
|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
ns
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
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.
4
_______________________________________________________________________________________
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
15
10
OUTPUT HIGH VOLTAGE (V)
-18
OUTPUT CURRENT (mA)
20
-16
-14
-12
-10
-8
-6
-4
5
3.30
MAX3483-02
-20
MAX3483-01
25
OUTPUT CURRENT (mA)
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
OUTPUT CURRENT vs.
RECEIVER OUTPUT HIGH VOLTAGE
IRO = 1.5mA
MAX3483-03
OUTPUT CURRENT vs.
RECEIVER OUTPUT LOW VOLTAGE
3.25
3.20
3.15
3.10
3.05
-2
0
1.0
1.5
2.0
2.5
3.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT HIGH VOLTAGE (V)
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
DRIVER OUTPUT CURRENT vs.
DIFFERENTIAL OUTPUT VOLTAGE
100
90
OUTPUT CURRENT (mA)
0.7
0.6
0.5
0.4
0.3
0.2
80
70
60
50
40
30
20
0.1
10
0
0
0
20
40
60
80
100
0.5
TEMPERATURE (°C)
1.0
1.5
2.0
2.5
3.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
OUTPUT CURRENT vs.
DRIVER OUTPUT LOW VOLTAGE
20
40
60
80
100
2.6
R = 54Ω
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
3.5
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
OUTPUT CURRENT vs.
DRIVER OUTPUT HIGH VOLTAGE
-100
MAX3483-07
OUTPUT CURRENT (mA)
150
0
1.6
0
175
-20
125
100
75
50
MAX3483-08
-20
OUTPUT CURRENT (mA)
-40
-40
DRIVER DIFFERENTIAL OUTPUT
VOLTAGE vs.TEMPERATURE
MAX3483-05
IRO = 2.5mA
3.5
TEMPERATURE (°C)
OUTPUT LOW VOLTAGE (V)
0.8
OUTPUT LOW VOLTAGE (V)
3.00
0
3.5
MAX3483-06
0.5
MAX3483-04
0
DIFFERENTIAL OUTPUT VOLTAGE (V)
0
-80
-60
-40
-20
25
0
0
0
2
4
6
8
10
OUTPUT LOW VOLTAGE (V)
12
-7 -6 -5 -4 -3 -2 -1 0 1 2 3
OUTPUT HIGH VOLTAGE (V)
4
5
_______________________________________________________________________________________
5
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
__________________________________________Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
_____________________________Typical Operating Characteristics (continued)
SHUTDOWN CURRENT
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
90
1.1
DE = VCC, RE = X
1.0
MAX3483-10
100
SHUTDOWN CURRENT (nA)
X = DON’T CARE
MAX3483-09
1.2
SUPPLY CURRENT (mA)
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
DE = 0, RE = 0
0.9
0.8
80
70
60
50
40
30
20
10
0.7
0
-40
-20
0
20
40
60
80
-40
100
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
______________________________________________________________Pin Description
PIN
6
MAX3483/
MAX3485/
MAX3486
MAX3488/
MAX3490
MAX3491
1
2
2
—
NAME
FUNCTION
2
RO
Receiver Output. If A > B by 200mV, RO will be high; if A < B by 200mV,
RO will be low.
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.
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
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
Ground
_______________________________________________________________________________________
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
TOP VIEW
RO
1
RE 2
DE 3
DI 4
R
D
1
VCC
RO
7
B
RE 2
6
A
DE 3
5
GND
DI 4
8
R
8 VCC
7 B
Rt
6
A
5 GND
D
DE
MAX3483
MAX3485
MAX3486
D
DI
B
Rt
A
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
VCC
VCC
TOP VIEW
MAX3488
MAX3490
1
5 Y
8
A
RO 2
7
B
DI 3
6
Z
VCC 1
GND 4
R
5
D
DI
3
Rt
D
6 Z
R
RO
8 A
RO
Y
2
R
Rt
D
7
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
14 V CC
R
13 V CC
RE
3
12 A
DE
4
11 B
DI
5
GND
6
GND
7
10 Z
D
5
MAX3491
Y
Rt
D
10
RO
R
Z
12
RO
2
R
9 Y
8 N.C.
DIP/SO
9
DI
VCC RE
VCC
13, 14
A
Rt
D
11
DI
B
N.C.
1, 8
3
6, 7
RE GND
GND
DE
Figure 3. MAX3491 Pin Configuration and Typical Operating Circuit
_______________________________________________________________________________________
7
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
375Ω
RL
2
VCM =
-7V to +12V
VOD
D
D
RL
2
VCC
VOD
RL
VOC
VCC
Figure 4. Driver VOD and VOC
VID
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
tDO
≈
50Ω
90%
VCC
OUT
CL
CL = 15pF (NOTE 5)
50%
10%
90%
50%
10%
tTD
Figure 7. Driver Differential Output Delay and Transition Times
8
_______________________________________________________________________________________
tTD
2.0V
≈ -2.0V
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
3V
VOM
IN
1.5V
1.5V
RL = 27Ω
0V
S1
GENERATOR
(NOTE 4)
tPLH
OUT
D
50Ω
CL = 15pF
(NOTE 5)
VCC
tPHL
VOH
Y
OUT
VOM
VOM
VOL
VOM =
VOH + VOL
2
tPHL
≈ 1.5V
tPLH
VOH
Z
OUT
VOM
VOM
VOL
Figure 8. Driver Propagation Times
3V
S1
0V OR 3V
OUT
D
IN
1.5V
1.5V
0V
GENERATOR
(NOTE 4)
RL = 110Ω
CL = 50pF
(NOTE 5)
tPZH
tPHZ
50Ω
0.25V
OUT
VOH + VOL
VOM =
2
VOH
VOM
≈ 1.5V
0V
Figure 9. Driver Enable and Disable Times (tPZH, tPSH, tPHZ)
VCC
3V
RL = 110Ω
S1
0V OR 3V
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)
_______________________________________________________________________________________
9
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
3.0V
GENERATOR
(NOTE 4)
VID
OUT
R
IN
50Ω
1.5V
1.5V
CL = 15pF
(NOTE 5)
0V
tRPLH
tRPHL
VCC
1.5V
VOM =
0V
VOM
OUT
VCC
2
VOM
0V
Figure 11. Receiver Propagation Delay
S1
S3
1.5V
1k
-1.5V
VID
VCC
R
S2
CL
(NOTE 5)
GENERATOR
(NOTE 4)
50Ω
3V
IN
1.5V
0V
3V
S1 OPEN
S2 CLOSED
S3 = 1.5V
IN
1.5V
0V
tPRZH
tPRSH
tPRZL
tPRSL
VOH
OUT
VCC
OUT
1.5V
1.5V
0V
VOL
3V
IN
S1 CLOSED
S2 OPEN
S3 = -1.5V
1.5V
0V
3V
S1 OPEN
S2 CLOSED
S3 = 1.5V
IN
1.5V
0V
S1 CLOSED
S2 OPEN
S3 = -1.5V
tPRHZ
OUT 0.25V
tPRLZ
VOH
OUT
VCC
0.25V
0V
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.
10
______________________________________________________________________________________
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
Devices with Receiver/Driver Enable
(MAX3483/MAX3485/MAX3486/MAX3491)
Table 1. Transmitting
INPUTS
OUTPUTS
MODE
RE
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
__________Applications Information
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.
* 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
RO
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
OUTPUTS
INPUTS
OUTPUT
DI
Z
Y
A, B
RO
1
0
1
≥ +0.2V
1
0
1
0
≤ -0.2V
0
Inputs Open
1
10dB/div
0Hz
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 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.
10dB/div
500kHz/div
5MHz
Figure 13. Driver Output Waveform and FFT Plot of MAX3485/
MAX3490/MAX3491 Transmitting a 125kHz Signal
0Hz
500kHz/div
5MHz
Figure 14. Driver Output Waveform and FFT Plot of MAX3483/
MAX3488 Transmitting a 125kHz Signal
______________________________________________________________________________________
11
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
____________________Function Tables
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
1µs/div
1µs/div
Figure 17. MAX3483/MAX3488 Driver 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
12
Figure 18. MAX3483/MAX3488 Receiver Propagation Delay
2µs/div
Figure 20. MAX3485/MAX3490/MAX3491 System Differential
Voltage at 125kHz Driving 4000 ft of Cable
______________________________________________________________________________________
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
120Ω
DI
DE
B
D
D
DI
DE
RO
RE
A
B
A
B
A
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
Line Length vs. Data Rate
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.
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.
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.
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.
______________________________________________________________________________________
13
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
120Ω
B
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
A
R
RO
RE
Y
120Ω
120Ω
D
B
Z
Z
B
DE
DE
DI
120Ω
D
Y
120Ω
Z
Y
B
A
Y
Z
R
DI
B
A
DE RE RO
R
A
R
D
D
DI
MAX3488
MAX3490
MAX3491
DE RE RO
NOTE: RE AND DE ON MAX3491 ONLY.
Figure 22. MAX3488/MAX3490/MAX3491 Full-Duplex RS-485 Network
MAX3488
MAX3490
MAX3491
A
RO
RE
R
120Ω
B
DATA IN
DE
Z
DI
D
120Ω
Y
DATA OUT
NOTE: RE AND DE ON MAX3491 ONLY.
Figure 23. Line Repeater for MAX3488/MAX3490/MAX3491
14
DI
______________________________________________________________________________________
RE
RO
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
PART
TEMP. RANGE
MAX3486CPA
0°C to +70°C
8 Plastic DIP
MAX3486CSA
MAX3486C/D
MAX3486EPA
MAX3486ESA
MAX3488CPA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 SO
Dice*
8 Plastic DIP
8 SO
8 Plastic DIP
MAX3488CSA
MAX3488C/D
MAX3488EPA
MAX3488ESA
MAX3490CPA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 SO
Dice*
8 Plastic DIP
8 SO
8 Plastic DIP
MAX3490CSA
MAX3490C/D
MAX3490EPA
MAX3490ESA
MAX3491CPD
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 SO
Dice*
8 Plastic DIP
8 SO
14 Plastic DIP
MAX3491CSD
MAX3491C/D
MAX3491EPD
MAX3491ESD
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
14 SO
Dice*
14 Plastic DIP
14 SO
__________________ Chip Topography
V CC
PIN-PACKAGE
RO
A
RE
B
Z/B
0.146"
(3.71mm)
DE
DI
Y/A
GND
* Contact factory for for dice specifications.
GND
0.086"
(2.18mm)
TRANSISTOR COUNT: 810
SUBSTRATE CONNECTED TO GROUND
______________________________________________________________________________________
15
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
_Ordering Information (continued)
MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
________________________________________________________Package Information
DIM
D
0°-8°
A
0.101mm
0.004in.
e
B
A1
C
E
L
SO
SMALL OUTLINE
PACKAGE
(0.150 in.)
H
A
A1
B
C
E
e
H
L
INCHES
MAX
MIN
0.069
0.053
0.010
0.004
0.019
0.014
0.010
0.007
0.157
0.150
0.050
0.244
0.228
0.050
0.016
DIM PINS
D
D
D
8
14
16
MILLIMETERS
MIN
MAX
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
3.80
4.00
1.27
5.80
6.20
0.40
1.27
INCHES
MILLIMETERS
MIN MAX
MIN
MAX
0.189 0.197 4.80
5.00
0.337 0.344 8.55
8.75
0.386 0.394 9.80 10.00
21-0041A
D
E
DIM
E1
A
A1
A2
A3
B
B1
C
D1
E
E1
e
eA
eB
L
A3
A A2
L A1
0° - 15°
C
e
B1
B
eA
eB
D1
Plastic DIP
PLASTIC
DUAL-IN-LINE
PACKAGE
(0.300 in.)
INCHES
MAX
MIN
0.200
–
–
0.015
0.175
0.125
0.080
0.055
0.022
0.016
0.065
0.045
0.012
0.008
0.080
0.005
0.325
0.300
0.310
0.240
–
0.100
–
0.300
0.400
–
0.150
0.115
DIM PINS
D
D
D
D
D
D
8
14
16
18
20
24
INCHES
MIN
MAX
0.348 0.390
0.735 0.765
0.745 0.765
0.885 0.915
1.015 1.045
1.14 1.265
MILLIMETERS
MIN
MAX
–
5.08
0.38
–
3.18
4.45
1.40
2.03
0.41
0.56
1.14
1.65
0.20
0.30
0.13
2.03
7.62
8.26
6.10
7.87
2.54
–
7.62
–
–
10.16
2.92
3.81
MILLIMETERS
MIN
MAX
8.84
9.91
18.67 19.43
18.92 19.43
22.48 23.24
25.78 26.54
28.96 32.13
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
© 1994 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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