ISO485

The ISO485 differential, isolated bus transceiver uses Burr-Brown's capacitively coupled isolation technology to provide high-speed, low cost bus isolation. The ISO485 is designed for bi-directional data communication on multipoint bus transmission lines and meets EIA Standard RS-485 as well as EIA Standard RS-422A requirements.

The ISO485 uses high voltage 0.4pF capacitors instead of the LED and photodetector which are used in equivalent optocoupler solutions. As a consequence the part count of the isolated RS-485 channel is reduced from multiple optocoupler channels, an RS- 485 transceiver chip and supporting circuitry to one ISO485. The capacitors in the ISO485 provide a high voltage barrier, 1500Vrms and greatly reduce current spikes on the power line.

The ISO485 combines a 3-state differential line driver and a differential-input line receiver both of which operate from a single 5V power supply. The driver differential outputs and the receiver differential input/ output bus ports are designed to offer minimum loading to the bus whenever the driver is disabled or V_S = 0V.