Choosing the Right Ferrite_ Comparing Core Materials
                     Choosing the Right 
Ferrite: Comparing Core 
Materials
Ferrite Cores
www.cosmoferrites.com
Overview
Only an EMC laboratory measurement can confirm that the ferrite is 
absolutely accurate. In most cases, calculating the dynamic impedance 
(transfer impedance) of an electronic circuit in the highest frequency 
range is not practical. This is dependent on a number of variables that 
are difficult to quantify mathematically, particularly in the HF range. 
However, an initial selection might be made based on experience and 
comparable measurements.
www.cosmoferrites.com
How to Choose the Right Ferrite?
In good designs, supply voltages or ground leads are in the range of 1 to 10Ω; 
usable signal lines are between 50 and 100Ω and greater, depending on the 
application (e.g., bus systems such as CAN, SCSI etc.). 
Based on the nomogram, you may discover the desired ferrite impedance (ZF) 
starting with this transfer impedance (ZA or ZB) and the desired interference 
suppression. Knowing the ferrite's impedance, you can find the right ferrite for 
the job, such as a ferrite sleeve or an SMD ferrite.
Wurth Electronics provides a Component Selector, a free software program that 
allows you to quickly and simply select SMD ferrites and other components, as 
well as simulate some of their functions.
www.cosmoferrites.com
Comparison of Ferrite Core Materials
Because of the frequency-dependent loss components, it's only practical 
to use the core materials for inductors within a specific frequency range. 
Beyond a typical frequency limit, core losses increase dramatically. The 
core material can be used as a filter element in this case.
Conclusions:
Iron powder materials (Fe): can be employed as a pure inductor up to 400 
kHz; beyond that, the loss component dominates in R, which is present up 
to 10 MHz (more, depending on the core material). In the frequency range 
commencing about 20MHz and higher, the core is no longer effective.
www.cosmoferrites.com
Continued..
● Manganese-zinc cores (MnZn) are inductive between 20 and 30 MHz. In the 
frequency range starting at 10MHz, increasing losses must be expected. The 
core material is no longer effective in the frequency band commencing about 
80MHz. 
● Nickel-zinc cores (NiZn) are inductive up to 60MHz, but the core material 
becomes lossy above that, up to 1GHz and beyond.
This qualitative analysis proves why nickel-zinc ferrites, in particular, have 
become well-established in the EMC range. It is the fundamental substance 
that acts as a filter over the broadest and most significant frequency range. 
MnZn ferrites have recently been used to decrease cable interference in the 
150kHz to 30MHz range. The STAR-FIX LFS snap ferrites and the WE-AFB LFS 
ferrite sleeves are available from Wurth Electronics.
www.cosmoferrites.com
Thank you
If you need more assistance, you can feel free to connect with our 
experts who will take you through our wide range of ferrite products 
available for several applications. Contact us @cosmo ferrites ltd
www.cosmoferrites.com