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PDF ADM488A Data sheet ( Hoja de datos )
| Número de pieza | ADM488A | |
| Descripción | EIA RS-485 Transceivers | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Data Sheet
Full-Duplex, Low Power,
Slew Rate Limited, EIA RS-485 Transceivers
ADM488A/ADM489A
FEATURES
Complies with ANSI TIA/EIA-485-A-1998 and
ISO 8482: 1987(E)
250 kbps data rate
±4 kV HBM ESD protection on all pins
Single 5 V ± 10% supply
−7 V to +12 V bus common-mode range
Connect up to 32 nodes on the bus
Reduced slew rate for low EM interference
Short-circuit protection
30 μA supply current
APPLICATIONS
Low power RS-485 and RS-422 systems
DTE-DCE interface
Packet switching
Local area networks
Data concentration
Data multiplexers
Integrated services digital network (ISDN)
GENERAL DESCRIPTION
The ADM488A and ADM489A are low power, differential line
transceivers suitable for communication on multipoint bus
transmission lines. They are intended for balanced data
transmission and comply with both RS-485 and RS-422
standards of the Electronics Industries Association (EIA). Both
products contain a single differential line driver and a single
differential line receiver, making them suitable for full-duplex
data transfer. The ADM489A contains an additional receiver
and driver enable control.
The input impedance is 12 kΩ, allowing 32 transceivers to be
connected on the bus. The ADM488A/ADM489A operate from
a single 5 V ± 10% power supply.
FUNCTIONAL BLOCK DIAGRAMS
ADM488A
RO R
A
B
DI D
Z
Y
Figure 1. ADM488A
ADM489A
A
RO R
B
RE
DE
DI D
Z
Y
Figure 2. ADM489A
Excessive power dissipation that is caused by bus contention or
output shorting is prevented by a thermal shutdown circuit. This
feature forces the driver output into a high impedance state if,
during fault conditions, a significant temperature increase is
detected in the internal driver circuitry.
The receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating).
The ADM488A/ADM489A are fabricated on BiCMOS, an
advanced mixed technology process combining low power
CMOS with fast switching bipolar technology.
The ADM488A/ADM489A are fully specified over the industrial
temperature range and are available in SOIC and MSOP packages.
Rev. B
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2009-2014 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
1 page  
Data Sheet
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 3.
Parameter
VCC
Inputs
Driver Input (DI)
Control Inputs (DE, RE)
Receiver Inputs (A, B)
Outputs
Driver Outputs
Receiver Output
Power Dissipation 8-Lead SOIC
θJA, Thermal Impedance
Power Dissipation 14-Lead SOIC
θJA, Thermal Impedance
Operating Temperature Range
Industrial (A Version)
Storage Temperature Range
Lead Temperature (Soldering, 10 sec)
Vapor Phase (60 sec)
Infrared (15 sec)
ESD Protection on All Pins
Human Body Model (HBM)
Rating
7V
−0.3 V to VCC + 0.3 V
−0.3 V to VCC + 0.3 V
−14 V to +14 V
−14 V to +12.5 V
−0.5 V to VCC + 0.5 V
520 mW
110°C/W
800 mW
120°C/W
−40°C to +85°C
−65°C to +150°C
300°C
215°C
220°C
±4 kV
ADM488A/ADM489A
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. B | Page 5 of 16
5 Page 
Data Sheet
ADM488A/ADM489A
THEORY OF OPERATION
The ADM488A/ADM489A are ruggedized RS-485 transceivers
that operate from a single 5 V supply. They contain protection
against radiated and conducted interference and are ideally suited
for operation in electrically harsh environments or where cables
can be plugged/unplugged. They are also immune to high RF
field strengths without special shielding precautions.
The ADM488A/ADM489A are intended for balanced data
transmission and comply with both EIA RS-485 and RS-422
standards. They contain a differential line driver and a differen-
tial line receiver, and are suitable for full-duplex data transmission.
The input impedance on the ADM488A/ADM489A is 12 kΩ,
allowing up to 32 transceivers on the differential bus. The
ADM488A/ADM489A operate from a single 5 V ± 10% power
supply. A thermal shutdown circuit prevents excessive power
dissipation caused by bus contention or by output shorting.
This feature forces the driver output into a high impedance state
if, during fault conditions, a significant temperature increase is
detected in the internal driver circuitry.
The receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating).
The ADM488A/ADM489A can transmit at data rates up to
250 kbps. Figure 20 shows a typical application for the
ADM488A/ADM489A, a full-duplex link where data transfers
at rates of up to 250 kbps. A terminating resistor is shown at
both ends of the link. This termination is not critical because
the slew rate is controlled by the ADM488A/ADM489A and
reflections are minimized.
The communications network can be extended to include
multipoint connections, as shown in Figure 22. As many as
32 transceivers can be connected to the bus.
Table 6 and Table 7 show the truth tables for transmitting and
receiving.
Table 6. Transmitting Truth Table
Inputs
RE DE DI Z
X1 1
10
X1 1
01
00
X1 High-Z
10
X1 High-Z
1 X is don’t care.
Table 7. Receiving Truth Table
Inputs
RE DE A to B
00
≥ +0.2 V
00
≤ −0.2 V
00
Inputs open circuit
10
X1
1 X is don’t care.
Outputs
Y
1
0
High-Z
High-Z
Output
RO
1
0
1
High-Z
VCC
ADM488A
RO R
VCC
A
B RT
Y
Z
ZB
DI D
Y
RT
VCC
A
GND
NOTES
1. MAXIMUM NUMBER OF NODES = 32.
Figure 20. ADM488A/ADM489A Full-Duplex Data Link
VCC
ADM488A
D
R
GND
DI
RO
Rev. B | Page 11 of 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ADM488A.PDF ] | |
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