What Are Ferrite Cores and Why Are They Used on Cables

Whether you are plugging in a laptop to a wall outlet for charging or are inserting a USB cable into a computer, you may have noticed the commonality of a large, nondescript cylinder that is located close to the connecting end of the cable. While you may not have thought much about the cylinder common to cables, it serves a very important role in connections and transfers. Known as ferrite cores, beads, or chokes, these cylinders are relied on for EMI management across a number of devices. While ferrite cores may play a diverse set of roles based on the application, this blog will be concerned with the operations of ferrite cores when they are specifically found on electronic cables.

As an element used for EMI protection, a ferrite core serves as a lowpass filter to guard a device. In a standard circuit, capacitors will operate as open when frequencies are low, while high frequencies will have them function as shorts. With consideration to Kirchoff’s voltage law, the total voltage of the loop will be equal to the sum of the drop across each component. It is important to know that both capacitors and inductors have a value known as capacitive reactance which is a counterpart to real number resistance. By adding resistance and reactance together as vectors, one will find the impedance value.

Utilizing impedance values, it is easier to understand an RC circuit as a voltage divider where reactance terms will raise under lower frequencies and drop under higher ones. As such, the reactance term of impedance will cause the capacitor to operate as an open when dominating below a certain cutoff frequency, while the capacitor will act as a short when impedance dominates above the cutoff frequency. With an understanding of such principles, one can see how circuit functionality changes based on a cutoff frequency. When conditions are at the cutoff frequency specifically, the power of the output signal will be halved, and an attenuation factor of 22 will be attained as resistance and reactance are equalized. With the dynamic response of the low pass circuit, the attenuation of signals will be permitted when values are equal to or greater than the cutoff frequency.

Through such properties, the ferrite bead serves as an non-idealized inductor acting as a short under low frequencies and an open at high frequencies. While low frequency conditions are present, current will move through the circuit unabated. However, one the cutoff frequency is met or surpassed, the ferrite bead will act as a short. Inductors store magnetic energy, and ferrite beads function to dissipate energy as heat. This ensures that cables do not transmit or receive RF signals to deter EMI issues. As such, they are quite useful for a grand number of applications, ensuring that power and data transfer is conducted with low issues or EMI. If you are in the market for various cable components and industrial parts, we have you covered here on NSN Orbit.

NSN Orbit is a website owned and operated by ASAP Semiconductor, and we are your sourcing solution with over 2 billion new, used, obsolete, and hard-to-find components readily available for purchase at any time. We are unmatched in our dedication to quality, choosing to only source items from leading global manufacturers that we trust. Furthermore, many offerings are subjected to varying levels of quality assurance measures prior to being sold, our checks ranging from visual inspections to third-party testing. As our team members are readily available for customers at any time, give us a call or email today, and we would be more than happy to assist you however we can!


Semiconductor's Certifications and Memberships
The only independent
distributor with a
  • All parts are stocked in the USA.
  • All parts are shipped from the USA.
  • All shipments must comply with U.S.A export laws.
  • No exceptions.

“We Proudly Support Intrepid Fallen Heroes Fund that serves United States Military Personal experiencing the Invisible Wounds of War : Traumatic Brain Injury (TBI) and Post Traumatic Stress (PTS). Please visit website (www.fallenheroesfund.org" rel="nofollow") and help in their valiant effort”.

Thank You for Visiting.

We Hope that You Will Visit Us Again the Next Time You Need NSN Parts and Make Us Your Strategic Purchasing Partner.

Request for Quote

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.