ISL8487E Datasheet, PDF (1/14 Pages) Intersil Corporation – ±15kV ESD Protected, 1/8 Unit Load, 5V, Low Power, High Speed or Slew Rate Limited, RS-485/RS-422 Transceivers

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Data Sheet
ISL8487E, ISL81487L, ISL81487E
September 15, 2005
FN6051.6
±15kV ESD Protected, 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 ESD protected,
fractional unit load (UL), BiCMOS, 5V powered, single
transceivers that meet both the RS-485 and RS-422
standards for balanced communication. Each driver output/
receiver input is protected against ±15kV ESD strikes,
without latch-up. Unlike competitive devices, this Intersil
family is specified for 10% tolerance supplies (4.5V to 5.5V).
All devices 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). 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 ISL8487E and ISL81487L
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
ISL81487E, which features higher slew rates.
Receiver (Rx) inputs feature a “fail-safe if open” 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
• RS-485 I/O Pin ESD Protection . . . . . . . . . . ±15kV HBM
- Class 3 ESD Level on all Other Pins . . . . . . >7kV HBM
• Fractional Unit Load Allows up to 256 Devices on the Bus
• Specified for 10% Tolerance Supplies
• High Data Rate Version (ISL81487E) . . . . . up to 5Mbps
• Slew Rate Limited Versions for Error Free Data
Transmission (ISL8487E, ISL81487L) . . . . .up to 250kbps
• Low Current Shutdown Mode (Except ISL81487E). . . 0.5µA
• Low Quiescent Supply Current:
- ISL8487E, ISL81487L . . . . . . . . . . . . . . . 145µA (Max.)
- ISL81487E . . . . . . . . . . . . . . . . . . . . . . . . 420µA (Max.)
• -7V to +12V Common Mode Input Voltage Range
• Three State Rx and Tx Outputs
• 30ns Propagation Delays, 5ns Skew (ISL81487E)
• Half Duplex Pinouts
• Operate from a Single +5V Supply (10% Tolerance)
• Current Limiting and Thermal Shutdown for Driver
Overload Protection
• Pin Compatible Replacements for: MAX487E, (ISL8487E);
LTC1487, ADM1487 (ISL81487L); MAX1487E, ST485ER
(ISL81487E)
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• High Node Count Networks
• Automated Utility Meter Reading Systems
• Factory Automation
• Security Networks
• Building Environmental Control Systems
• Industrial/Process Control Networks
TABLE 1. SUMMARY OF FEATURES
PART
NUMBER
ISL8487E
HALF/FULL NO. OF DEVICES DATA RATE SLEW-RATE
RECEIVER/ QUIESCENT LOW POWER PIN
DUPLEX ALLOWED ON BUS (Mbps)
LIMITED? DRIVER ENABLE? I_CC (µA) SHUTDOWN? COUNT
Half
256
0.25
Yes
Yes
120
Yes
8
ISL81487L
Half
256
0.25
Yes
Yes
120
Yes
8
ISL81487E
Half
256
5
No
Yes
350
No
8
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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