What is ISO/IEC 9549 - Galvanic isolation of balanced interchange circuits about?
ISO/IEC 9549 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.
Note: ISO/IEC 9549 does not describe a complete equipment interface in terms of mechanical, electrical, and functional/procedural specifications.
Who is ISO/IEC 9549 - Galvanic isolation of balanced interchange circuits for?
ISO/IEC 9549 on galvanic isolation of balanced interchange circuits is useful for:
- Designers of balanced interchange circuits
- Manufacturing and industrial organizations involved in balanced interchange circuits
- Government authorities   
- Regulatory bodies 
- Computer & Network Security department 
- Mobile Communications manufacturer 
Why should you use ISO/IEC 9549 - Galvanic isolation of balanced interchange circuits?
Galvanic isolation of interchange circuits is required whenever the intercommunicating devices are connected to different mains supplies. In this case, the ground potential difference between the earthing systems frequently is higher than the common-mode voltage specified for the interchange circuit receiver. Transmission errors and even damage to the receiver may be the result.
ISO/IEC 9549 specifies a method of galvanically isolating signal exchanges on balanced interchange circuits using optocoupler integrated circuit technology. ISO/IEC 9549 includes parameters and measurements for an isolated generator and an isolated receiver. These components are 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.
Overall, ISO/IEC 9549 will assist you with isolated generator high impedance control, the isolated receiver circuit failure detection capability, and line termination in a point-to-point configuration.
