Common-mode choke core selection
For low-frequency common-mode noise (10 kHz–1 MHz) nanocrystalline rings give the highest impedance per volume. MnZn ferrite covers 100 kHz–1 MHz at lower cost, and NiZn handles 1–500 MHz. Selection depends on the noise spectrum and the required impedance.
Practical tip
Ask for the impedance curve at your frequency, not just µi — impedance includes winding capacitance and core loss.
