Overview
IEC 62358:2026 is an international standard published by the International Electrotechnical Commission (IEC) that specifies the standard inductance factor (AL value) and its tolerances for a wide range of gapped ferrite cores. This standard applies to Pot, RM, ETD, E, EER, EP, PQ, PM, EC, EFD, and other low-profile core shapes commonly used in magnetic components for electronic devices.
The main objective of this standard is to provide a uniform system for specifying AL values and tolerances, which leads to better interchangeability, improved supply chain management, and streamlined design processes for manufacturers and users of ferrite core-based inductive components.
New in this edition:
- Addition of AL values and tolerances for PM-cores, EC-cores, and EFD-cores, expanding coverage and offering designers more standardized options.
Key Topics
- Standardization of AL (Inductance Factor) Values: Defines preferred AL values for gapped ferrite cores, facilitating compatibility and easier specification.
- Tolerance Letter Coding: Specifies a system of letter codes (such as A, J, E, K) corresponding to standard tolerance levels on AL values, enabling clear and concise tolerance specifications.
- Core Types Covered:
- Pot-cores
- RM-cores
- ETD-cores
- E-cores
- EER-cores
- EP-cores
- PQ-cores
- PM-cores (new)
- EC-cores (new)
- EFD-cores (new)
- Various low-profile planar cores
- Measuring Method: Requires use of the methods specified in IEC 62044-2 for determining the inductance factor to ensure accuracy and consistency.
- Selection of Preferred Numbers: Uses the R10 series from ISO 497 to define standard AL values.
Applications
Adherence to IEC 62358:2026 enables consistent and reliable design of ferrite core-based inductive components such as transformers and chokes, which are widely used in:
- Power supplies (including switch-mode power supplies and adapters)
- Telecommunications equipment
- Signal filtering applications
- Consumer electronics (e.g., TVs, computers)
- Industrial control systems
- Research and development: Ensures rapid prototyping by enabling use of standard parts with guaranteed performance and availability.
Key practical benefits include:
- Interchangeability: Use of standard AL values and tolerances ensures components from different suppliers are compatible.
- Shorter lead times: Standardization allows suppliers to stock common gapped cores, expediting delivery for both sampling and production.
- Reduced inventory risks: Streamlines component selection and management, mitigating issues of obsolete or excess stock.
- Design efficiency: Simplifies specification and tolerancing, helping engineers focus on high-level electrical requirements rather than individual core parameters.
Related Standards
Several IEC standards relate to core geometries and measuring methods complementary to IEC 62358:2026, including:
- IEC 62044-2: Cores made of soft magnetic materials - Measuring methods - Part 2: Magnetic properties at low excitation level.
- IEC 63093 series: Ferrite cores - Guidelines on dimensions and the limits of surface irregularities, with separate parts for each major core type:
- ISO 497: Guide to the choice of series of preferred numbers and of series containing more rounded values of preferred numbers.
Conclusion
IEC 62358:2026 plays a crucial role in the standardization of ferrite core AL values and tolerances, supporting efficient, reliable, and interchangeable design and procurement of magnetic components across the electronics industry. By adopting these standard values, organizations benefit from improved product consistency, logistics, and quality control, making IEC 62358:2026 essential for anyone specifying or manufacturing components using gapped ferrite cores.
