ISO/IEC 9549:1990 PDF

This International Standard specifies galvanic isolation of balanced interchange circuits using optocoupler integrated circuit technology and is provided for data transmission in the two-condition code (e.g. NRZ).

The electrical characteristics are compatible with both ISO 8482 and CCITT Recommendation V.11

The specifications are given in terms of parameters and measurements for an isolated generator and an isolated receiver. These components may be used in twisted pair 2-wire or 4-wire point-to-point connections up to 1 000 m or multipoint connections up to 500 m for speeds up to 2 Mbit/s for point-to-point connections and 1 Mbit/s for multipoint connections. For data signalling rates up to 20 kbit/s, device manufacturers may optimize their component design.

Options are provided to meet special application requirements, such as

• isolated generator high impedance control;
• isolated receiver circuit failure detection capability;
• line termination in point-to-point configuration

This International Standard does not describe a complete equipment interface in terms of mechanical, electrical and functional /procedural specifications.