What is a Common Mode Filter Chokes?
A common mode choke is an electrical filter that blocks high-frequency noise common to two or more data or power lines while allowing the desired DC or low-frequency signal to pass. Common mode (CM) noise current is typically radiated from sources such as unwanted radio signals, unshielded electronics, inverters, and motors. Left unfiltered, this noise presents interference problems in electronics and electrical circuits.
Common mode chokes arer commonly used in industrical, electrical and telecommunications applications to remove or decrease noise and related electromagnetic interference.
How Do Common Mode Chokes Work?
In normal or differential mode (single choke), current travels on one line in one direction from the source to the load, and in the opposite direction on the return line that completes the circuit. In common mode, the noise current travels on both lines in the same direction
In common mode, the current in a group of lines travels in the same direction so the combined magnetic flux adds to create an opposing field to block the noise, as illustrated by the red and green arrows in the toroid core shown in Figure 1. In differential mode, the current travels in opposite directions and the flux subtracts or cancels out so that the field does not oppose the normal mode signal.
Chokes are divided into 2 broad classes:
- Audio frequency chokes (AFC) – designed to block audio and power line frequencies while allowing DC to pass
- Radio frequency chokes (RFC) – designed to block radio requencies while allowing audio and DC to pass.
How do I Choose a Common Mode Choke?
When choosing the common mode choke to meet your requirement, the main criteria for selecting a common mode choke are:
- Required impedance: How much attenuation of noise is needed?
- Required frequency range: Over what frequency bandwidth is the noise?
- Required current-handling: How much differential mode current must it handle?
What Types of Common Mode Chokes does Baohui Manufacture?
Baohui designs and manufactures a variety of common mode chokes for many applications. Choose a category below or use one of our tools to find the right common mode choke for your application:
