The ISL8485, ISL8490, and ISL8491 RS-485 / RS-422 devices are BiCMOS 5V powered, single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. Unlike competitive devices, this family is specified for 10% tolerance supplies (4. 5V to 5. 5V). The ISL8485, ISL8490, and ISL8491 feature data rates up to 5Mbps. All devices present a single unit load to the RS-485 bus, which allows up to 32 transceivers on the network. The receiver (Rx) inputs feature a “fail-safe if open” design, which ensures a logic high Rx output if the Rx inputs are floating. The 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. The ISL8490 and ISL8491 are configured for full duplex (separate Rx input and Tx output pins) applications. Half duplex configurations (ISL8485) multiplex the Rx inputs and Tx outputs to allow transceivers with Rx and Tx disable functions in 8 Ld packages.


  • Specified for 10% tolerance supplies
  • Class 3 ESD protection (HBM) on all pins: 7kV
  • High data rates: up to 5Mbps
  • Single unit load allows up to 32 devices on the bus
  • Low quiescent current: 500µA
  • -7V to +12V common-mode input voltage range
  • Three state Rx and Tx outputs (except ISL8490)
  • 30ns propagation delays, 5ns skew
  • Full duplex and half duplex pinouts
  • Operation from a single +5V supply (10% tolerance)
  • Current limiting and thermal shutdown for driver overload protection
  • Pb-free plus anneal (RoHS compliant)




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


Design & Development