Under high temperature conditions, how much should the rated current of the common mode inductor be derated? How can the derating curve be obtained?

Derating ratio and curve acquisition method

Reason for derating: High temperature leads to a decrease in magnetic permeability of the magnetic core and an increase in resistance of the copper wire, resulting in a more severe temperature rise. It is necessary to reduce the current to avoid saturation or overheating failure.

Typical derating range: Ferrite core: approximately 5% to 10% derating per 10°C increase, typically entering a rapid derating zone after 70°C to 85°C.

Automotive-grade applications: According to the AEC-Q200 standard, the current may need to be reduced to less than 50% of the rated value at room temperature at 125°C.

Derating curve acquisition methods: Manufacturer's specification book: directly providing temperature-current derating curve; Certification standard reference: AEC-Q200 or MIL-STD-202 specifications require verification of current carrying capacity after temperature cycling; Self-built testing: gradually increasing temperature in an environmental chamber and monitoring inductance temperature rise/impedance changes, drawing measured curves.