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Demystifying Common Mode Chokes: A Comprehensive Guide

Demystifying Common Mode Chokes: A Comprehensive Guide


Electric circuits operate within specified bands of frequencies, i.e., they will catch frequencies falling in a particular band for further processing. Any other frequency will be considered as noise – disturbances cause distraction for the circuits. This is where the common mode chokes jump in to save the day and ensure filtering out all those unwanted frequencies.

These disturbances are named electromagnetic interference that gets suppressed by the common mode chokes to increase the system's overall efficiency. In this article, we will delve deeper into the common mode chokes, their types, working, advantages, and more. So, without any further delay, let’s begin exploring!

The Concept of Common Mode Noise

To grasp the concept of common mode chokes, you will first need to develop an understanding of the common mode noises. These refer to the signals of varied frequency sourcing from electronic devices, switching circuits, or power lines. The extent of interference they offer depends on their frequency and intensity. However, the interferences they offer include:

Signal Disturbances – Signal disturbance can occur when the interfering noise and the actual signals collapse, resulting in errors in data transmission. Besides this, the system can also experience affected accuracy, cross talks, and more such detrimental issues.  

Complete or Partial Malfunctioning – These noises can also cause partial or complete circuit malfunctioning, causing reduced productivity. This phenomenon is normally observed in sensitive equipment, including control systems or medical devices.

Increased Production of Heat – Sound or any other waves have a particle nature. When two particles collide, energy is released in the form of heat. The same interaction happens between the common mode noise and the actual signal, causing the overall heating of the system. Sometimes, this overproduction of heat can even cause premature failure of the component.

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Common Mode Chokes

All the problems mentioned above can be avoided with common mode chokes. These chokes help eliminate radiofrequency current and electromagnetic interference to ensure smooth processing, whether manufacturing, data processing, or any other. In general, common mode chokes are of two different types:

1. Through-Hole Common Mode Chokes

These chokes are specifically designed for mounting using the holes drilled into PCBs, the Printed Circuit Boards. This type is known for its compatibility with higher electrical currents and better durability.

2. Surface-Mount Common Mode Chokes

On the other hand, we have the surface-mount chokes that are directly attached or mounted to the PCBs’ surface. Owing to their compact size and cost-effectiveness, these chokes are best for use in compact circuits or those operating with high-frequencies.

Other types include the toroidal, which can be amorphous or nanocrystalline common mode chokes, E-core, Multistage, and more.

How Do These Chokes Work?

Let's now jump into the workings of these electronic components! Common mode chokes come with dual wires that wrap around a magnetic or ferrite core to make a choke structure. Its goal of common mode noise filtration is split into two main processes, i.e., directing the noise current in one direction across both its wires and generating a magnetic field with multiple windings. The overall noise reduction is achieved with the combined effect of both these processes.

Normally, electric circuits have two sorts of disturbances, either common mode noise or differential mode noise. In both cases, enough magnetic field isn’t produced to completely cancel or add up the two magnetic fields. In the case of the common mode chokes, there’s no differential noise but only common mode one. It mainly focuses on preventing the issues caused by common mode noises.

Advantages of Using the Common Mode Chokes

Signal filtering is not the only benefit common mode chokes offer. With them, you can obtain multiple other perks too. These include:

Improved Signal Quality – On filtration, signal's quality will surely improve, increasing the overall efficiency of the system. Thus, you can assume their output to be reliable.

High Inductance – Reduces disturbance refers to reduced resistance, which, in turn, improves the inductance of the electronic circuit. This will ensure increased production of emf and, thus, the induced current.

Efficient Space Usage – Compared to the other options in the markets, these chokes are relatively small and better functioning than the competitors. In short, they seem to be an ideal option for applications with minimal space.

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Applications of Common Mode Chokes

Now comes the main part, i.e., the applications where common mode chokes are mainly used. Let’s give them a quick read!

Electric Vehicles

Electric vehicles are recently getting immense hype due to their reduced carbon dioxide emission and minimized contribution to pollution. These vehicles are powered by electric motors instead of the internal combustion engine.

Common mode chokes find their application in EV charging, where they contribute to reducing the common mode noise caused by rapid switching of the high-current components.

Renewable Energy

As non-renewable resources are becoming extinct depending on their extended usage, everyone is in pursuit of adopting renewable energy consumption. These mainly involve the usage of waves, rain, tides, and sunlight as the energy source used for off-grid energy services, transportation, electricity generation, etc.

Common mode chokes are utilized in these processes to ensure control of electromagnetic interference. With reduced interference, the system's overall efficiency will increase, making your circuits, inverters, or other equipment more productive.

Motor Drivers

These chokes are important electronic components in AC and DC motor drivers to handle frequent bearing failure. So, you won't have to spend that much cost on changing the equipment over and over.

Medical Equipment

Medical equipment is meant to be safe and reliable for ensuring the safety of the patients. With a common mode choke, diagnostic or monitoring equipment is considered more reliable.

Lighting and Audio System

You will also find these chokes used in LED lighting systems, fluorescent lighting systems, power amplifiers, preamplifiers, and other electronic components to not only strengthen the signals but also make them accurate and reliable, improving the overall effectiveness and life of the system.

Instrument Transformer

These also find applications in the instrument transformers that need to operate at high frequency, transferring almost the same output strength as in the input. This accuracy can be achieved using common mode chokes that ensure zero disturbance in ideal cases, meaning no more wastage of input signals due to distortion or any other interference.  

Communication Systems

Communication demands receiving accurate and distortion-free signals; otherwise, the signals would get wasted being inaudible. These chokes are mainly utilized in telecommunication systems, ethernet interfaces, etc.

Factors to Consider When Choosing the Right Common Mode Choke

The following are key factors that you should consider when browsing the best-of-the-best common mode chokes for your equipment:


Impedance has a direct influence on the effectiveness level of electromagnetic interference suppression. Chokes with a higher impedance tend to be ideal in controlling interference and vice versa.

Specific Application Usage

Another important thing to consider is your specific application usage. For instance, chokes used in high-power electric vehicles need to be strong enough to withstand temperature fluctuations and harsh environmental conditions. In contrast, those in household appliances don't need to be that powerful or robust.

Physical Size

It also depends on where you want to implant the choke. If you want to make a miniaturized version of the equipment, you will have to rely on the surface mount chokes. On the other hand, the applications, including the handling of higher currents, demand chokes of somehow bigger size, and these are normally of the through-hole type.

Current Rating

Your choke’s current rating should be compatible with the system’s specs. Because the underrated chokes not only fail in the accomplishment of interference prevention but also make the system prone to failure due to overheating.

Where to Get the Premium Common Mode Chokes from?

You must have planned on getting the premium common mode chokes by now. If so, we suggest checking out the TranSmart’s official website. They offer multiple types of common mode chokes in bulk. The best part? You can get them customized per your requirements of structure and specification.

Their Nanocrystalline Common Mode Choke Core has exceptional features, including excellent impedance character, smaller choke size for compact equipment designing, high induction with reduced winding capabilities, and more. You can use them in home appliances, frequency converters, switch-mode power supplies, EMC fillers, etc. Please visit their official website for detailed information.


Common mode chokes are widely used wherever the signal distortion needs to be minimized, and the electromagnetic interference needs to be controlled. It comes in different types, all working on the same mechanism and offering diverse perks. We have also highlighted the applications of these chokes with a detailed analysis of the factors you should consider when getting them.

Hope all this helped you develop an in-depth understanding of the topic. If you plan on getting them in extended quantity, get in touch with the TranSmart! Their dedication towards quality standards assurance will surely leave you impressed. 

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