ADM1486AR ,+5 V Low Power RS-485 PROFIBUS TransceiverSPECIFICATIONSCC MIN MAXParameter Min Typ Max Unit Test Conditions/CommentsDRIVERDifferential Outpu ..
ADM1486AR-REEL7 ,+5 V Low Power RS-485 PROFIBUS TransceiverSPECIFICATIONSCC MIN MAXParameter Min Typ Max Unit Test Conditions/CommentsDRIVERPropagation Delay ..
ADM1486ARZ ,+5 V Low Power RS-485 PROFIBUS TransceiverSPECIFICATIONSCC MIN MAXParameter Min Typ Max Unit Test Conditions/CommentsDRIVERDifferential Outpu ..
ADM1486ARZ-REEL7 ,+5 V Low Power RS-485 PROFIBUS TransceiverSpecifications subject to change without notice.–2– REV. 0ADM1486ABSOLUTE MAXIMUM RATINGS* Operatin ..
ADM1486ARZ-REEL7 ,+5 V Low Power RS-485 PROFIBUS Transceiverapplications. The part containsThe receiver contains a fail-safe feature that results in a logica d ..
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ADM1486AR
+5 V Low Power RS-485 PROFIBUS Transceiver
REV Pr. B
+5 V Low Power
RS-485 PROFIBUS Transceiver
FUNCTIONAL BLOCK DIAGRAMFEATURES
Meets & Exceeds EIA RS-485 & EIA RS-422 Standard
50 Mb/s Data Rate
Recommended for PROFIBUS Applications
2.1V Minimum Differential Output with 54�����
Termination
Low Power 0.5mA ICC
Thermal Shutdown & Short Circuit Protection
Zero Skew Driver & Receiver
Driver Propagation Delay: 8 ns
Receiver Propagation Delay: 12 ns
High Z Outputs with Drivers Disabled or Power Off
Superior Upgrade for SN65ALS1176
15kV HBM ESD Protection on I/O Pins A & B
Available in Standard 8-pin SOIC & Miniature 8-pin
Micro SOIC packages
APPLICATIONS
Industrial Field Equipment
GENERAL DESCRIPTIONThe ADM1486 is a differential line transceiver suitable
for high speed bidirectional data communication on
multipoint bus transmission lines. It is designed for
balanced data transmission, complies with EIA Standards
RS-485 and RS-422 and is recommended for PROFIBUS
applications. The part contains a differential line driver
and a differential line receiver. Both the driver and the
receiver may be enabled independently. When disabled or
with power off, the driver outputs are tristated.
The ADM1486 operates from a single +5 V power supply.
Excessive power dissipation caused by bus contention or
by 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.
Up to 50 transceivers may be connected simultaneously on
a bus, but only one driver should be enabled at any time.
It is important therefore that the remaining disabled
drivers do not load the bus. To ensure this, the ADM1486
driver features high output impedance when disabled and
also when powered down.
This minimizes the loading effect when the transceiver is
not being utilized. The high impedance driver output is
maintained over the entire common-mode voltage range
from –7 V to +12 V.
The receiver contains a fail safe feature which results in a
logic high output state if the inputs are unconnected
(floating).
The ADM1486 is fabricated on BiCMOS, an advanced
mixed technology process combining low power CMOS
with fast switching bipolar technology. All inputs and
outputs contain protection against ESD; all driver outputs
feature high source and sink current capability. An epi-
taxial layer is used to guard against latch-up.
The ADM1486 features extremely fast switching speeds.
Minimal driver propagation delays permit transmission at
data rates up to 50 Mbits/s while low skew minimizes
EMI interference.
The part is fully specified over the commercial and indus-
trial temperature range and is available in an 8-lead
DIL/SOIC/µSOIC package.
ADM1486–SPECIFICATIONS(VCC = +5 V ± 5%. All specifications TMIN to TMAX unless otherwise noted.)
RECEIVERSpecifications subject to change without notice.
TIMING SPECIFICATIONS (VCC = +5 V ± 5%. All specifications TMIN to TMAX unless otherwise noted.)DRIVER
Specifications subject to change without notice.
CAUTIONESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V
readily accumulate on the human body and test equipment and can discharge without
ABSOLUTE MAXIMUM RATINGS*(TA = +25°C unless otherwise noted)
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+7 V
Inputs
Driver Input (DI) . . . . . . . . . . . .–0.3 V to VCC + 0.3 V
Control Inputs (DE, RE) . . . . . .–0.3 V to VCC + 0.3 V
Receiver Inputs (A, B) . . . . . . . . . . . . . .–9 V to +14 V
Outputs
Driver Outputs . . . . . . . . . . . . . . . . . . . .–9 V to +14 V
Receiver Output . . . . . . . . . . . . .–0.5 V to VCC + 0.5 V
Power Dissipation 8-Lead DIP . . . . . . . . . . . . . .500 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . .+130°C/W
Power Dissipation 8-Lead SOIC . . . . . . . . . . . .450 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . .+170°C/W
Power Dissipation 8-Lead Cerdip . . . . . . . . . . . .500 mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . .+125°C/W
Power Dissipation 8-Lead µSOIC . . . . . . . . . . . . . . mW
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . .+°C/W
Operating Temperature Range
Commercial (J Version) . . . . . . . . . . . . . .0°C to +70°C
Industrial (A Version) . . . . . . . . . . . . . .–40°C to +85°C
Storage Temperature Range . . . . . . .–65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . .+300°C
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . .+215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . .+220°C
*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 listed in the operational sections of this
specification is not implied. Exposure to absolute maximum ratings for extended
periods of time may affect device reliability.
Table I.TransmittingRERERE
Table II.ReceivingRERERE
PIN FUNCTION DESCRIPTION
PIN CONFIGURATION
ORDERING GUIDEGND
VCC
ADM1486
Test CircuitsFigure 1.Driver Voltage Measurement Test Circuit
Figure 2.Driver Voltage Measurement Test Circuit 2
Figure 3.Driver Propagation Delay Test Circuit
Figure 4.Driver Enable/Disable Test Circuit
Figure 5.Receiver Propagation Delay Test Circuit
Figure 6.Receiver Enable/Disable Test Circuit
Switching CharacteristicsFigure 7.Driver Propagation Delay, Rise/Fall Timing
Figure 9.Receiver Propagation Delay
Figure 11.Typical RS-485 Network
Table III.Comparison of RS-422 and RS-485 Interface Standards
ADM1486
APPLICATIONS INFORMATION
Differential Data TransmissionDifferential data transmission is used to reliably transmit
data at high rates over long distances and through noisy
environments. Differential transmission nullifies the effects
of ground shifts and noise signals which appear as
common-mode voltages on the line. There are two main
standards approved by the Electronics Industries Association
(EIA) which specify the electrical characteristics of trans-
ceivers used in differential data transmission.
The RS-422 standard specifies data rates up to 10 MBaud
and line lengths up to 4000 ft. A single driver can drive a
transmission line with up to 10 receivers.
In order to cater for true multipoint communications, the
RS-485 standard was defined. This standard meets or
exceeds all the requirements of RS-422 but also allows for
up to 32 drivers and 32 receivers to be connected to a
single bus. An extended common-mode range of –7 V to
+12 V is defined. The most significant difference between
RS-422 and RS-485 is the fact that the drivers may be
disabled thereby allowing more than one (32 in fact) to be
connected to a single line. Only one driver should be
enabled at time, but the RS-485 standard contains addi-
tional specifications to guarantee device safety in the event
of line contention.
Cable and Data RateThe transmission line of choice for RS-485
communications is a twisted pair. Twisted pair cable tends
to cancel common-mode noise and also causes cancella-
tion of the magnetic fields generated by the current
flowing through each wire, thereby, reducing the effective
inductance of the pair.
The ADM1486 is designed for bidirectional data commu-
nications on multipoint transmission lines. A typical
application showing a multipoint transmission network is
illustrated in Figure 11. An RS-485 transmission line can
have as many as 32 transceivers on the bus. Only one
driver can transmit at a particular time but multiple
receivers may be enabled simultaneously.
As with any transmission line, it is important that
reflections are minimized. This may be achieved by
terminating the extreme ends of the line using resistors
equal to the characteristic impedance of the line. Stub
lengths of the main line should also be kept as short as
possible. A properly terminated transmission line appears
purely resistive to the driver.
Thermal ShutdownThe ADM1486 contains thermal shutdown circuitry
which protects the part from excessive power dissipation
during fault conditions. Shorting the driver outputs to a
low impedance source can result in high driver currents.
The thermal sensing circuitry detects the increase in die
temperature and disables the driver outputs. The thermal
sensing circuitry is designed to disable the driver outputs
when a die temperature of 150°C is reached. As the device
cools, the drivers are re-enabled at 140°C.
Propagation DelayThe ADM1486 features very low propagation delay
ensuring maximum baud rate operation. The driver is
well balanced ensuring distortion free transmission.
Another important specification is a measure of the skew
between the complementary outputs. Excessive skew
impairs the noise immunity of the system and increases
the amount of electromagnetic interference (EMI).
Receiver Open-Circuit Fail SafeThe receiver input includes a fail-safe feature which
guarantees a logic high on the receiver when the inputs
are open circuit or floating.
