廬
ISL8487, ISL81483, ISL81487
Data Sheet
December 2003
FN6050.2
1/8 Unit Load, 5V, Low Power, High Speed
or Slew Rate Limited, RS-485/RS-422
Transceivers
These Intersil RS-485/RS-422 devices are 鈥渇ractional鈥?unit
load (UL), BiCMOS, 5V powered, single transceivers that
meet both the RS-485 and RS-422 standards for balanced
communication. Unlike competitive devices, this Intersil
family is specified for 10% tolerance supplies (4.5V to 5.5V).
The ISL81483 and ISL81487 present a 1/8 unit load to the
RS-485 bus, which allows up to 256 transceivers on the
network for large node count systems (e.g., process
automation, remote meter reading systems). The 1/4 UL
ISL8487 allows up to 128 transceivers on the bus. In a
remote utility meter reading system, individual (apartments
for example) utility meter readings are routed to a
concentrator via an RS-485 network, so the high allowed
node count minimizes the number of repeaters required to
network all the meters. Data for all meters is then read out
from the concentrator via a single access port, or a wireless
link.
Slew rate limited drivers on the ISL8487 and ISL81483
reduce EMI, and minimize reflections from improperly
terminated transmission lines, or unterminated stubs in
multidrop and multipoint applications. Data rates up to
250kbps are achievable with these devices.
Data rates up to 5Mbps are achievable by using the
ISL81487, which features higher slew rates.
Receiver (Rx) inputs feature a 鈥渇ail-safe if open鈥?design,
which ensures a logic high Rx output if Rx inputs are
floating.
Driver (Tx) outputs are short circuit protected, even for
voltages exceeding the power supply voltage. Additionally,
on-chip thermal shutdown circuitry disables the Tx outputs to
prevent damage if power dissipation becomes excessive.
These half duplex devices multiplex the Rx inputs and Tx
outputs to allow transceivers with Rx and Tx disable
functions in 8 lead packages.
Features
鈥?Fractional Unit Load Allows up to 256 Devices on the Bus
鈥?Specified for 10% Tolerance Supplies
鈥?Class 3 ESD Protection (HBM) on all Pins. . . . . . . . >7kV
鈥?High Data Rate Version (ISL81487). . . . . . . up to 5Mbps
鈥?Slew Rate Limited Versions for Error Free Data
Transmission (ISL8487, ISL81483) . . . . . . .up to 250kbps
鈥?Low Current Shutdown Mode (Except ISL81487) . . . 1nA
鈥?Low Quiescent Supply Current:
- ISL8487, ISL81483. . . . . . . . . . . . . . . . . . 120
碌
A (Max.)
- ISL81487 . . . . . . . . . . . . . . . . . . . . . . . . . 300
碌
A (Max.)
鈥?-7V to +12V Common Mode Input Voltage Range
鈥?Three State Rx and Tx Outputs
鈥?30ns Propagation Delays, 5ns Skew (ISL81487)
鈥?Half Duplex Pinouts
鈥?Operate from a Single +5V Supply (10% Tolerance)
鈥?Current Limiting and Thermal Shutdown for driver
Overload Protection
鈥?Drop-In Replacements for: MAX487 (ISL8487); MAX1483
(ISL81483); MAX1487, LMS1487 (ISL81487)
Applications
鈥?High Node Count Networks
鈥?Automated Utility Meter Reading Systems
鈥?Factory Automation
鈥?Security Networks
鈥?Building Environmental Control Systems
鈥?Industrial/Process Control Networks
TABLE 1. SUMMARY OF FEATURES
PART
NUMBER
ISL8487
ISL81483
ISL81487
HALF/FULL
DUPLEX
Half
Half
Half
NO. OF DEVICES
DATA RATE SLEW-RATE
RECEIVER/
QUIESCENT
ALLOWED ON BUS
(Mbps)
LIMITED?
DRIVER ENABLE?
I
CC
(碌A(chǔ))
128
256
256
0.25
0.25
5
Yes
Yes
No
Yes
Yes
Yes
100
100
250
LOW POWER
SHUTDOWN?
Yes
Yes
No
PIN
COUNT
8
8
8
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
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Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright 漏 Intersil Americas Inc. 2003. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
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