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PDF ( 数据手册 , 数据表 ) MAX491

零件编号 MAX491
描述 Slew-Rate-Limited RS-485/RS-422 Transceivers
制造商 Maxim Integrated
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MAX491 数据手册, 描述, 功能
MAX481/MAX483/MAX485/
MAX487–MAX491/MAX1487
Low-Power, Slew-Rate-Limited
RS-485/RS-422 Transceivers
General Description
The MAX481, MAX483, MAX485, MAX487–MAX491, and
MAX1487 are low-power transceivers for RS-485 and RS-
422 communication. Each part contains one driver and one
receiver. The MAX483, MAX487, MAX488, and MAX489
feature reduced slew-rate drivers that minimize EMI and
reduce reflections caused by improperly terminated cables,
thus allowing error-free data transmission up to 250kbps.
The driver slew rates of the MAX481, MAX485, MAX490,
MAX491, and MAX1487 are not limited, allowing them to
transmit up to 2.5Mbps.
These transceivers draw between 120µA and 500µA of
supply current when unloaded or fully loaded with disabled
drivers. Additionally, the MAX481, MAX483, and MAX487
have a low-current shutdown mode in which they consume
only 0.1µA. All parts operate from a single 5V supply.
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-imped-
ance state. The receiver input has a fail-safe feature that
guarantees a logic-high output if the input is open circuit.
The MAX487 and MAX1487 feature quarter-unit-load
receiver input impedance, allowing up to 128 MAX487/
MAX1487 transceivers on the bus. Full-duplex communi-
cations are obtained using the MAX488–MAX491, while
the MAX481, MAX483, MAX485, MAX487, and MAX1487
are designed for half-duplex applications.
________________________Applications
Low-Power RS-485 Transceivers
Low-Power RS-422 Transceivers
Level Translators
Transceivers for EMI-Sensitive Applications
Industrial-Control Local Area Networks
__Next Generation Device Features
o For Fault-Tolerant Applications
MAX3430: ±80V Fault-Protected, Fail-Safe, 1/4
Unit Load, +3.3V, RS-485 Transceiver
MAX3440E–MAX3444E: ±15kV ESD-Protected,
±60V Fault-Protected, 10Mbps, Fail-Safe,
RS-485/J1708 Transceivers
o For Space-Constrained Applications
MAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,
Profibus RS-485/RS-422 Transceivers
MAX3362: +3.3V, High-Speed, RS-485/RS-422
Transceiver in a SOT23 Package
MAX3280E–MAX3284E: ±15kV ESD-Protected,
52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422,
True Fail-Safe Receivers
MAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,
SOT23, RS-485/RS-422 Transmitters
o For Multiple Transceiver Applications
MAX3030E–MAX3033E: ±15kV ESD-Protected,
+3.3V, Quad RS-422 Transmitters
o For Fail-Safe Applications
MAX3080–MAX3089: Fail-Safe, High-Speed
(10Mbps), Slew-Rate-Limited RS-485/RS-422
Transceivers
o For Low-Voltage Applications
MAX3483E/MAX3485E/MAX3486E/MAX3488E/
MAX3490E/MAX3491E: +3.3V Powered, ±15kV
ESD-Protected, 12Mbps, Slew-Rate-Limited,
True RS-485/RS-422 Transceivers
Ordering Information appears at end of data sheet.
______________________________________________________________Selection Table
PART HALF/FULL
NUMBER DUPLEX
MAX481
MAX483
MAX485
MAX487
MAX488
MAX489
MAX490
MAX491
MAX1487
Half
Half
Half
Half
Full
Full
Full
Full
Half
DATA
RATE
(Mbps)
2.5
0.25
2.5
0.25
0.25
0.25
2.5
2.5
2.5
SLEW-RATE
LIMITED
LOW-
POWER
SHUTDOWN
RECEIVER/
DRIVER
ENABLE
QUIESCENT
CURRENT
(μA)
NUMBER OF
RECEIVERS ON
BUS
No Yes Yes 300
32
Yes Yes Yes 120
32
No No Yes 300
32
Yes Yes Yes 120
128
Yes No No 120
32
Yes No Yes 120
32
No No No 300
32
No No Yes 300
32
No No Yes 230
128
PIN
COUNT
8
8
8
8
8
14
8
14
8
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-0122; Rev 10; 9/14







MAX491 pdf, 数据表
MAX481/MAX483/MAX485/
MAX487–MAX491/MAX1487
Low-Power, Slew-Rate-Limited
RS-485/RS-422 Transceivers
TOP VIEW
VCC 1
RO 2
DI 3
GND 4
R
D
8A
7B
6Z
5Y
VCC
1
3
DI
D
5Y
6Z
MAX488
MAX490
Rt
VCC
R
DIP/SO
B1
A2
VCC 3
RO 4
MAX488
MAX490
8Z
7Y
6 GND
5 DI
2
RO
8A
R
Rt
7
B
4
GND
D
GND
μMAX
NOTE: TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.
Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating Circuit
RO
DI
TOP VIEW
N.C. 1
RO 2
RE 3
DE 4
DI 5
GND 6
GND 7
14 VCC
R 13 N.C.
12 A
11 B
10 Z
D
9Y
8 N.C.
DIP/SO
DI 5
RO 2
NC 1, 8, 13
DE VCC
4 14
D
R
9Y
10
Z
12 A
Rt
11
B
3 6, 7
RE GND
MAX489
MAX491
VCC RE
Rt R
D
GND DE
RO
DI
Figure 3. MAX489/MAX491 Pin Configuration and Typical Operating Circuit
__________Applications Information
The MAX481/MAX483/MAX485/MAX487–MAX491 and
MAX1487 are low-power transceivers for RS-485 and RS-
422 communications. The MAX481, MAX485, MAX490,
MAX491, and MAX1487 can transmit and receive at data
rates up to 2.5Mbps, while the MAX483, MAX487,
MAX488, and MAX489 are specified for data rates up to
250kbps. The MAX488–MAX491 are full-duplex trans-
ceivers while the MAX481, MAX483, MAX485, MAX487,
and MAX1487 are half-duplex. In addition, Driver Enable
(DE) and Receiver Enable (RE) pins are included on the
MAX481, MAX483, MAX485, MAX487, MAX489,
MAX491, and MAX1487. When disabled, the driver and
receiver outputs are high impedance.
MAX487/MAX1487:
128 Transceivers on the Bus
The 48kΩ, 1/4-unit-load receiver input impedance of the
MAX487 and MAX1487 allows up to 128 transceivers
on a bus, compared to the 1-unit load (12kΩ input
impedance) of standard RS-485 drivers (32 trans-
ceivers maximum). Any combination of MAX487/
MAX1487 and other RS-485 transceivers with a total of
32 unit loads or less can be put on the bus. The
MAX481/MAX483/MAX485 and MAX488–MAX491 have
standard 12kΩ Receiver Input impedance.
8 Maxim Integrated







MAX491 equivalent, schematic
MAX481/MAX483/MAX485/
MAX487–MAX491/MAX1487
Low-Power, Slew-Rate-Limited
RS-485/RS-422 Transceivers
Package Information
For the latest package outline information and land patterns, go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-”
in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
PACKAGE TYPE
8 PDIP
8 SO
8 MAX
8 CERDIP
14 PDIP
14 SO
14 CERDIP
PACKAGE CODE
P8-1
S8-2
U8-1
J8-2
P14-3
S14-1
J14-3
OUTLINE NO.
21-0043
21-0041
21-0036
21-0045
21-0043
21-0041
21-0045
LAND PATTERN NO.
90-0096
90-0092
90-0112
16 Maxim Integrated










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