In the world of isolation technology, designing a reinforced digital isolation integrated circuit (IC) that meets the performance specifications and standards of the harsh industrial environment is challenging. Testing and delivering such an isolator with consistently good safety margins presents an additional layer of complexity for the IC manufacturer. But the system designer has the most unenviable tasks: Evaluate many components, understand their specifications and claims, and finally, choose the device that best meets their system’s requirements.
For the system designer, some of the most difficult challenges to meet are the electromagnetic compliance (EMC) requirements. These are system-level requirements, so designers usually must wait to test for compliance near the end of their design cycle. , Added to this is the rising pressure to accelerate product development cycles. To do this and design efficiently, designers often must restrict the number of devices they consider for their systems. Choosing components with upfront knowledge of their EMC impact will go a long way to ensure first-pass compliance. For this, the system designer has to rely on suppliers’ collateral, such as product datasheets, user guides and application notes, in order to make a judgment early in their design cycle.
Standards like IEC-61000-4-x, VDE-0884-10 and CISPR22 define the EMC tests and pass/fail criteria for systems and components. Electrostatic discharge (ESD), electronic fast transient (EFT), immunity to radiated and conducted emissions, radiation emissions from the device, and common mode transient immunity are some of the tests that quantify how a component will perform in the harsh industrial environment.
It is important to understand the exact conditions and setup in which the component claims to comply with the EMC standards and assess how the actual system might differ from the test set-up. Typical questions designers can ask are:
- Does the device need additional components to comply with the standard? Are there other solutions that can give the same performance without these additional components?
- Is there a complex PCB design guideline to be met? What is the effect of any parasitic elements that these PCB structures can cause?
- Are there contradicting requirements to achieve the performance on all the relevant standards? For example, if achieving the best ESD performance requires a large ground plane and the best radiated susceptibility requires a small ground plane, how is the vendor testing to ensure best performance in a system?
My new white paper, Understanding Electro-Magnetic-Compliance Tests in Digital Isolators, dives deep into this topic. This paper addresses the above questions and more, and shows how the new ISO7842 family of reinforced digital isolators delivers on all the relevant EMC standards, without enforcing any unreasonable system design constraints. Transparency in how components are tested for EMC compliance will give system designers confidence that their system will get EMC certified.
Additional resources:
- Learn more about reinforced digital isolators including TI’s newest ISO7842 high-immunity, high-speed 5700 Vrms reinforced quad-channel digital isolator.
- Check out a video on common mode transient immunity (CMTI) and how it relates to digital isolators from one of our analog experts, Hanan Abdulahi.