What is a ferrite core?
Ferrite cores are used in transmission systems to address two types of electrical noise: differential mode and common mode. Common mode noise refers to unwanted signals that do not carry any useful information. A ferrite core cable is specifically designed to eliminate this type of noise, whether it comes from signal lines or power cables. It works by suppressing electromagnetic interference—blocking noise at lower frequencies and absorbing it at higher ones—which helps to maintain cleaner signal transmission. This guide explains more, covering:
What is the difference between ferrite cores and ferrite beads?
Types of ferrites
Key applications of ferrite cores
Ferrite core size table
What is the difference between ferrite cores and ferrite beads?
Both ferrite cores and ferrite beads serve as EMI filters. That’s where the similarities end.
Ferrite cores
Ferrite cores come in different shapes and sizes. A ferrite ring is an example. They’re generally larger than ferrite beads. They’re typically used externally, clamped onto cables or enclosed around multiple wires.
When used externally, ferrite cores are most often configured as single-pass, with a cable passing once through the core. However, multi-pass configurations can also be applied to enhance noise suppression when needed.
A ferrite core cable is mostly used to suppress common mode noise in transmission systems by presenting high impedance to high-frequency signals. It does this by absorbing or dissipating them to reduce EMI. They’re effective across a broad frequency range, typically beginning in the MHz range.
Ferrite beads
Ferrite beads are compact components that resemble tiny cylinders or resistors. In surface-mount designs, they commonly allow a conductor to pass through their core.
Also known as ferrite chokes, these beads are designed to target differential noise on individual lines. While they’re typically used in single-pass configurations, multi-pass bead setups are also possible. They suppress specific high-frequency ranges with more precision and are ideal for managing EMI in compact, sensitive electronic designs.
Installation differences
Ferrite cores can usually be added after assembly, especially the snap-on or clamp types used on external cables.
Ferrite beads must be designed into the PCB layout from the start and soldered during board assembly.
Browse our ferrite passive components
Types of ferrites
Our range features both single and multi-pass configurations.
Flat cable ferrite cores
Our flat ferrite core cable reduces noise on flat and ribbon cables. They suppress electromagnetic emissions by blocking low-frequency noise and absorbing high-frequency interference emitted from signal or power lines. This makes them highly effective for EMI suppression and RFI (radio frequency interference) control.
Our range includes a variety of insert lengths and MHz impedance ratings, with multiple configurations available to suit different flat and ribbon cable types.
Specifications:
● Ferrite material: A5 and K5B (RMS-303)
● Casing material: Nylon 6/6 (RMS-244)
● Clip & Spring material: Stainless steel (RMS-305)
● Colours available: Black and grey
Ferrite beads
Ferrite beads are passive components widely used in electronic circuits to reduce high-frequency interference and unwanted signal noise. By filtering out these disturbances, they help maintain stable power quality in printed circuit boards (PCBs).
Our selection includes single and multi-pass designs, available in various formats such as wound beads, axial types, multi-line suppressors, and toroidal configurations, providing flexibility for different applications.
Specifications:
● Ferrite material: K5B (RMS-303)
● Adhesive: RMS-301
● Wire types: RMS-306, RMS-307, RMS-308
● Colour: Black
Ferrite sleeves
Our range of solid and split ferrite sleeves are suitable for use as suppression cores and shielding beads on round cables. Designed to fit various cable diameters, they support a range of EMI control applications.
Split ferrite sleeves feature a clamp-style design with high-performance A5 ferrite material. Ideal for EMI suppression in retrofit and testing scenarios, they install easily thanks to a polyamide housing. Their magnetic properties block interference without affecting signal waveforms, making them ideal for digital equipment such as PCs, displays, fax machines, and printers. They can be fitted over cables or wire harnesses, with a binding band for a secure placement.
Solid ferrite sleeves act as shielding beads that maintain consistent impedance across a wide frequency range. Commonly used in wire assemblies and the MATV/CATV sectors, some variants feature a ring shape for multi-turn suppression, enhancing performance over broader frequencies.
Specifications:
● Ferrite Materials: A5, 3A5, G7, K5B
● Casing Material: Polyamide 6.6
● Colour: Black
● Flame Rating: UL94 V-0
Ferrite toolbox
Our ferrite toolkit features a curated collection of 30 distinct components, including ferrite rings, toroids, split cores, and beads. Developed with engineers in mind, its compact and neatly arranged design makes it an excellent resource for testing, prototyping, and comparing material performance.
Our experts help you learn more in our Guide to ferrite beads, sleeves and cores.
Key applications of ferrite cores
Ferrite cores might be small, but they play a big role in helping electronic devices run smoothly. They’re great at blocking unwanted noise and interference, keeping signals clean and devices working reliably. Whether inside a circuit or clipped onto a cable, ferrite cores help protect everything from laptops to power supplies. Here’s a quick look at where they’re most useful and how they make a difference.
What else should you know? Check out Your PCB substrate: a guide to materials.
| Application area | Use | Common devices |
| EMI suppression | Filters noise from cables and circuits | Computers, TVs, power bricks |
| Signal integrity | Reduces distortion and crosstalk | Routers, servers, industrial automation |
| Power line filtering | Blocks switching noise in power circuits | Power adapters, LED drivers, SMPS |
| RFI mitigation | Protects from high-frequency interference | Radios, medical devices, IoT hardware |
| Retrofitting & testing | EMI control without circuit changes | R&D setups, field diagnostics, EMC labs |
If you’re designing a PCB for your application, you’ll also need other components. Learn more in our experts’ Buyer's guide to PCB hardware.
Also see our Circuit board hardware – the design engineer's guide.
Ferrite-core-size table
The table below lists our options by size. Tip: Choose a compact core for space-sensitive applications like handheld devices. Opt for a medium or large core when dealing with longer cable runs or environments with higher EMI.
|
Size category |
Insert length (mm) |
Overall length (mm) |
Overall width (mm) |
Impedance @100 MHz (Ω) |
Impedance @25 MHz (Ω) |
|
Compact (≤15 mm) |
7.2 |
9.1 |
7.8 |
41 |
19 |
|
Compact (≤15 mm) |
9.7 |
13.8 |
1.8 |
32 |
10 |
|
Compact (≤15 mm) |
11.5 |
16.0 |
8.0 |
72 |
29 |
|
Compact (≤15 mm) |
11.5 |
16.0 |
12.0 |
63 |
41 |
|
Compact (≤15 mm) |
14.0 |
18.0 |
8.0 |
164 |
45 |
|
Medium (15–30 mm) |
16.5 |
20.5 |
15.0 |
97 |
36 |
|
Medium (15–30 mm) |
18.0 |
23.8 |
7.0 |
47 |
21 |
|
Medium (15–30 mm) |
20.0 |
23.8 |
7.0 |
47 |
21 |
|
Medium (15–30 mm) |
21.0 |
25.0 |
12.0 |
70 |
35 |
|
Medium (15–30 mm) |
21.5 |
25.5 |
12.0 |
87 |
27 |
|
Medium (15–30 mm) |
21.5 |
25.5 |
15.0 |
110 |
39 |
|
Medium (15–30 mm) |
21.5 |
25.5 |
15.0 |
126 |
48 |
|
Medium (15–30 mm) |
23.5 |
28.5 |
8.0 |
65 |
28 |
|
Medium (15–30 mm) |
27.0 |
33.5 |
10.0 |
57 |
26 |
|
Medium (15–30 mm) |
27.0 |
33.5 |
20.0 |
149 |
58 |
|
Medium (15–30 mm) |
27.0 |
33.5 |
12.0 |
66 |
30 |
|
Large (>30 mm) |
31.0 |
31.0 |
20.0 |
121 |
42 |
|
Large (>30 mm) |
31.0 |
36.0 |
8.0 |
79 |
29 |
|
Large (>30 mm) |
34.4 |
45.1 |
28.5 |
195 |
95 |
|
Large (>30 mm) |
34.4 |
45.5 |
10.0 |
110 |
43 |
|
Large (>30 mm) |
35.0 |
38.5 |
12.0 |
68 |
25 |
|
Large (>30 mm) |
35.0 |
40.0 |
10.0 |
64 |
25 |
|
Large (>30 mm) |
35.0 |
40.0 |
12.0 |
59 |
24 |
|
Large (>30 mm) |
40.0 |
45.2 |
12.0 |
195 |
95 |
|
Large (>30 mm) |
52.0 |
63.5 |
28.5 |
152 |
77 |
Download free CADs
Free CADs are available for most solutions, which you can download. If you’re not quite sure which ferrite cores will work best for your application, our experts are always happy to advise you. Whatever your requirements, you can depend on fast dispatch.
You might find it helpful to also check out our expert Guide to PCB standoffs.
Questions?
Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application at 0345 528 0474.