ISL31480E_11 Datasheet, PDF (1/24 Pages) Intersil Corporation – Fault Protected, Extended CMR, RS-485/RS-422 Transceivers with Cable Invert

Fault Protected, Extended CMR, RS-485/RS-422
Transceivers with Cable Invert
ISL31480E, ISL31483E, ISL31485E, ISL31486E
The ISL3148xE are fault protected, 5V powered differential
transceivers that exceed the RS-485 and RS-422 standards for
balanced communication. The RS-485 transceiver pins (driver
outputs and receiver inputs) are fault protected up to ±60V.
Additionally, the extended common mode range allows these
transceivers to operate in environments with common mode
voltages up to ±25V (>2X the RS-485 requirement), making this
fault protected RS-485 family one of the most robust on the
market.
Transmitters deliver an exceptional 2.5V (typical) differential
output voltage into the RS-485 specified 54Ω load. This yields
better noise immunity than standard RS-485 ICs, or allows up to
six 120Ω terminations in star network topologies.
Receiver (Rx) inputs feature a “Full Fail-Safe” design, which
ensures a logic high Rx output if Rx inputs are floating, shorted, or
on a terminated but undriven (idle) bus.
The ISL31483E, ISL31485E and ISL31486E include cable invert
functions that reverse the polarity of the Rx and/or Tx bus pins in
case the cable is misconnected. Unlike competing devices, Rx full
fail-safe operation is maintained even when the Rx input polarity is
switched.
The ISL31480E and ISL31486E feature a logic supply (V_L) pin
that sets the V_OH of the Rx outputs, and the switching points of
the logic input pins, to be compatible with a lower supply voltage
(down to 1.8V) in mixed voltage systems. See Table 1 on page 2
for key features and configurations by device number.
Features
• Fault Protected RS-485 Bus Pins . . . . . . . . . . . . . . up to ±60V
• Extended Common Mode Range . . . . . . . . . . . . . . . . . . . ±25V
More Than Twice the Range Required for RS-485
• Cable Invert Pins (Except ISL31480)
Corrects for Reversed Cable Connections While Maintaining Rx
Full Fail-safe Functionality
• Logic Supply (V_L) Pin (ISL31480E, ISL31486E)
Simplifies Interface to Lower Voltage Logic Devices
• Full Fail-safe (Open, Short, Terminated) RS-485 Receivers
• 1/4 Unit Load (UL) for up to 128 Devices on the Bus
• High Rx I_OL for Opto-Couplers in Isolated Designs
• Hot Plug Circuitry - Tx and Rx Outputs Remain Three-State
During Power-up/Power-down
• Slew Rate Limited RS-485 Data Rate . . . . . . . . . . . . . 1Mbps
• Low Quiescent Supply Current . . . . . . . . . . . . . . . . . . . 2.3mA
Ultra Low Shutdown Supply Current . . . . . . . . . . . . . . . 10µA
Applications
• Utility Meters/Automated Meter Reading Systems
• High Node Count RS-485 Systems
• PROFIBUS® and RS-485 Based Field Bus Networks, and
Factory Automation
• Security Camera Networks
• Building Lighting and Environmental Control Systems
• Industrial/Process Control Networks
30
B
25
A
20
VID = ±1V
15
10
5
RO
0
-5
TIME (400ns/DIV)
FIGURE 1. EXCEPTIONAL Rx OPERATES AT 1Mbps EVEN WITH
±25V COMMON MODE VOLTAGE
25
12
0
-7
-12
-20
-25
STANDARD RS-485 CLOSEST
TRANSCEIVER COMPETITOR
ISL3148XE
FIGURE 2. TRANSCEIVERS DELIVER SUPERIOR COMMON
MODE RANGE vs. STANDARD RS-485 DEVICES
January 20, 2011
1
FN7638.2
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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