Choosing the Right Ferrite: Comparing Core Materials - PowerPoint PPT Presentation

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Choosing the Right Ferrite: Comparing Core Materials

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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. – PowerPoint PPT presentation

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Title: Choosing the Right Ferrite: Comparing Core Materials


1
Choosing the Right Ferrite Comparing Core
Materials
2
Ferrite Cores
www.cosmoferrites.com
3
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.

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4
How to Choose the Right Ferrite?
  • In good designs, supply voltages or ground leads
    are in the range of 1 to 10O usable signal lines
    are between 50 and 100O 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
5
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.

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6
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.

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7
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
    _at_cosmo ferrites ltd

www.cosmoferrites.com
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