What is a Choke Coil?
A choke coil is a part used in electrical circuits to allow DC current to flow through while blocking AC current from passing. These coils are used in a number of electrical devices. When used as part of a radio’s circuitry, it falls into one of two frequency classes: audio or radio. Those used in circuits with higher frequencies use different core materials than those used in lower frequency circuits.
During the process of sending a signal through a circuit, the idea is to let the desired signal go through while filtering out other, unwanted signals. One type of unwanted signal is common-mode noise, which is filtered out by a common-mode choke coil. Power lines are an example of a source of common-mode noise. Without a coil, the power line would create a lot of electrical noise as it travels to its destination, which would then be received on the other end and possibly cause interference with the signal.
Inductors that are used to help filter signals are called chokes
The choke coil works because it acts as an inductor. When the current passing through changes, as AC currents do, it typically creates a magnetic field in the coil that works against that current. This property, known as inductance, blocks most of the AC current from passing through. As a result, currents that do not change, such as DC currents, can continue through while those that do are blocked by the very magnetic field they created.
At the core of this part is a material used to produce its magnetic field. Coils used to filter higher frequencies may use an air-core or a ferrite core, while lower frequency coils may use an iron core. The material in the core determines the strength of the magnetic field and the inductance rate of the coil.
Inductors are similar to capacitors, with one key difference in how they work. Both store electrical charges that pass through them, but capacitors store the charge inside an insulator located between two conductors on the capacitor. A choke coil stores the electric charge in the magnetic field created around it instead of on any specific part of the coil itself. Both parts are used in electronic circuitry, but capacitors typically store electric charges while these coils filter them.
How to choose choke coil?
When choosing the best type to use in a circuit, the engineer will look at the voltage, the DC resistance of the coil, and the level of inductance. These factors determine which coil will most efficiently pass through the correct currents while blocking the unwanted ones. The frequency to be passed through determines the best types to use.
What is the use of common mode choke coils?
Common mode chokes are used in order to filter common mode electromagnetic interference (EMI) currents without de-rating under high currents and without causing signal degradation. Common mode chokes are applied to supply and return pairs of conductors and are ideal for EMI filtering of signal and power lines. Common mode chokes can withstand high DC currents without filtering performance degradation, which is an issue that can happen with differential mode filters such as small chip beads.
Types of Common Mode Chokes
There are many different kinds of common mode chokes and at Future Electronics we stock many of the most common types categorized by case size / dimension, impedance, rated current, maximum DC resistance, packaging type and rated voltage. The parametric filters on our website can help refine your search results depending on the required specifications.
The most common sizes for rated voltage are 50 V, 250 V and 500 V. We also carry common mode chokes with rated voltage as high as 250 kV. Rated current can be between 0.4 mA and 23 A, with the most frequent common mode chokes having a rated current of 500 mA, 1A or 2 A.
Applications for common mode chokes
Common Mode Chokes can be used in several industrial, electronic and telecommunication applications including:
- Automotive applications (ex: CAN bus)
- Suppression of radiation noise in electronic devices
- Countering common mode noise affecting signals in high-speed lines
- USB line for PCs and peripheral equipment.
- IEEE1394 lines for PCs
- Panel link lines for LCD panels
Customised choke coil and common mode choke
Prisource provide our customers with solutions to meet their individual requirements, manufactured and type tested to any standard and specification. All products are designed to meet the strictest safety standards throughout the world, such as UL, CCC, etc.
Prisource choke coil series
Choke coils with iron powder core
Features: High current and inductance capability；Low cost and high efficiency；Freqency range from 10KHZ to 100KHZ
Applications: Switching power supply；EMI filter
SMD Choke Coils
Features: High current and inducatance capability；Design for surface mounting；Excellent solderability and reliability
Applications: Notebook inverter；Sweitching regulator；Power supply
Note: 1.Inductance drop less than 10% at DC rated current.；2. Inductance measure at 10KHz 0.3V.；3. Temperature rise less than 40℃ at rated current.
Low cost choke coil with high saturation current
cymbal choke is a drum stroke which consists of striking a cymbal with a drum stick.
Prisource common mode choke series
UU Type common mode choke
Features: Excellent frequency characteristics；Small size and large Inductance；Voltage rated：250 VAC
Applications: Switching power supply；EMI filter；Monitor
Note: Thermal class：A (105°C)；Withstand voltage：2000 VAC between windings；Testing condition：1 KHz 0.3V；Temperature rise：40°C MAX.
EE Type common mode choke
Features: Excellent frequency characteristics；Small size and large Inductance；Voltage rated：250 VAC
Applications: Switching power supply；EMI filter；Monitor
Note: Thermal class：A (105°C)；Withstand voltage：2000 VAC between windings；Testing condition：1 KHz 0.3V；Temperature rise：40°C MAX.
EU Type common mode choke
Features: Excellent frequency characteristics；Small size and large Inductance；Voltage rated：250 VAC
Applications: Switching power supply；EMI filter；Monitor
Note: Thermal class：A (105°C)；Withstand voltage：2000 VAC between windings；Testing condition：1 KHz 0.3V；Temperature rise：40°C MAX.
TOROIDAL Type common mode choke
Features: Excellent frequency characteristics；Small size and large Inductance；Voltage rated：250 VAC
Applications: Switching power supply；EMI filter；Monitor
Note: Thermal class：A (105°C)；Withstand voltage：2000 VAC between windings；Testing condition：1 KHz 0.3V；Temperature rise：40°C MAX.
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