ISL32470E Datasheet, PDF (1/19 Pages) Intersil Corporation – Fault Protected, Extended Common Mode Range, RS-485/RS-422 Transceivers

Fault Protected, Extended Common Mode Range,
RS-485/RS-422 Transceivers with ±16.5kV ESD
ISL32470E, ISL32472E, ISL32475E, ISL32478E
The ISL32470E, ISL32472E, ISL32475E, ISL32478E are
fault-protected, extended common mode range differential
transceivers that exceed the RS-485 and RS-422 standards for
balanced communication. The RS-485 bus pins (driver outputs
and receiver inputs) are fault protected against overvoltages up to
±60V and are protected against ±16.5kV ESD strikes without
latch-up. Additionally, these transceivers operate in environments
with common mode voltages up to ±15V (exceeds the RS-485
requirement), making this fault-protected RS-485 family one of
the more robust on the market.
Transmitters (Tx) 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 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. Rx outputs feature high
drive levels; typically, 15mA @ V_OL = 1V (to ease the design of
opto-coupled isolated interfaces).
Half duplex (Rx inputs and Tx outputs multiplexed together) and
full duplex pinouts are available. See Table 1 on page 2 for key
features and configurations by device number.
For a fault-protected RS-485 transceiver with a ±25V extended
common mode range, please see the ISL32490E and ISL32483E
data sheets.
Features
• Fault-Protected RS-485 Bus Pins . . . . . . . . . . . . . . Up to ±60V
• Extended Common Mode Range . . . . . . . . . . . . . . . . . . . ±15V
Larger Than Required for RS-485
• 1/4 Unit Load for Up to 128 Devices on the Bus
• ±16.5kV HBM ESD Protection on RS-485 Bus Pins
• High Transient Over-Voltage Tolerance . . . . . . . . . . . . . . .±80V
• Full Fail-Safe (Open, Short, Terminated) RS-485 Receivers
• 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
• Choice of RS-485 Data Rates . . . . . . . . . . . .250kbps to 15Mbps
• 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
20
B
15
A
10
V_ID = ±1V
5
RO
0
-5
TIME (20ns/DIV)
FIGURE 1. EXCEPTIONAL Rx OPERATES AT >15Mbps EVEN WITH
±15V COMMON MODE VOLTAGE
15
12
0
-7
-15
STANDARD RS-485
TRANSCEIVER
ISL3247xE
FIGURE 2. TRANSCEIVERS DELIVER SUPERIOR COMMON MODE
RANGE vs STANDARD RS-485 DEVICES
January 21, 2011
1
FN7784.0
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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