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The ISL4489E, ISL4491E are ESD protected, "fractional" unit load, BiCMOS, 5V powered, single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. Each driver output and receiver input is protected against ±15kV ESD strikes, without latch-up. Unlike competitive versions, these Intersil devices are specified for 10% tolerance supplies (4.5V to 5.5V).

Rx inputs and Tx outputs present a "1/8 unit load" to the RS-485 bus, which allows a total of 256 transmitters and receivers on the network for large node count systems.

These devices are configured for full duplex (separate Rx input and Tx output pins) applications, so they are ideal for RS-422 networks requiring high ESD tolerance on the bus pins.

The ISL4489E utilizes a slew rate limited driver which reduces EMI, and minimizes reflections from improperly terminated transmission lines, or unterminated stubs in multidrop and multipoint applications.

Data rates up to 15Mbps are achievable by using the ISL4491E, 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.

Key Features

• Pb-free Available as an Option (RoHS Compliant) (See Ordering Info)
• RS-485 I/O Pin ESD Protection ±15kV HBM
  • Class 3 ESD Level on all Other Pins >7kV HBM
• 1/8 Unit Load Allows up to 256 Devices on the Bus
• High Data Rates (ISL4491E) up to 15Mbps
• Slew Rate Limited Version for Error Free Data Transmission (ISL4489E)
• Very Low Quiescent Current:
  • 140µA (ISL4489E)
  • 370µA (ISL4491E)
• -7V to +12V Common Mode Input Voltage Range
• Three-State Rx and Tx Outputs
• Full Duplex Pinout
• Operates from a Single +5V Supply (10% Tolerance)
• Current Limiting and Thermal Shutdown for driver Overload Protection

Applications

• Factory Automation
• Security Networks
• Building Environmental Control Systems
• Industrial/Process Control Networks
• Level Translators (e.g., RS-232 to RS-422)
• RS-232 "Extension Cords"