ISO485

® ISO 485 ISO485 Isolated RS-485 DIFFERENTIAL BUS TRANSCEIVER FEATURES q RS-485 AND RS-422 COMPATIBLE q 100% TESTED FOR HIGH-VOLTAGE BREAKDOWN q q q q RATED 1500Vrms SINGLE-WIDE 24-PIN PLASTIC DIP EASY TO USE LOW POWER: 180mW typ at 5Mbit/s DESCRIPTION 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 RS485 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 VS = 0V. 3 VSA 15 VSB APPLICATIONS q MULTIPOINT DATA TRANSMISSION ON LONG BUS LINES IN NOISY ENVIRONMENTS 2 RE A B 12 13 1 R 24 D TRUTH TABLE RS-485 DE ...