Common Mode Chokes

Image	Part Number	Description / PDF	Quantity	Rfq
	CMT2-7-R PowerStor (Eaton)	CMC 3.2MH 4.4A 2LN TH	0
	CMT1-9-R PowerStor (Eaton)	CMC 1.85MH 4.53A 2LN TH	0
	CMT4-1-R PowerStor (Eaton)	CMC 5.4MH 2A 2LN TH	0
	CMT4-4-R PowerStor (Eaton)	CMC 1.3MH 4A 2LN TH	0
	CMT2-9-R PowerStor (Eaton)	CMC 2MH 5.45A 2LN TH	0
	CMT1-8-R PowerStor (Eaton)	CMC 2.4MH 3.85A 2LN TH	0
	CMT1-10-R PowerStor (Eaton)	CMC 940UH 6.05A 2LN TH	0
	CMT3-6-R PowerStor (Eaton)	CMC 530UH 6.5A 2LN TH	0
	CMT4-3-R PowerStor (Eaton)	CMC 2.7MH 3A 2LN TH	0
	CMT1-7-R PowerStor (Eaton)	CMC 4.2MH 2.89A 2LN TH	0
	CMT2-3-R PowerStor (Eaton)	CMC 12MH 2.45A 2LN TH	0
	CMT2-5-R PowerStor (Eaton)	CMC 6MH 3.4A 2LN TH	0
	CMT1-2-R PowerStor (Eaton)	CMC 49MH 880MA 2LN TH	0

Common Mode Chokes

1. Overview

Common Mode Chokes (CMCs) are passive electronic components designed to suppress electromagnetic interference (EMI) by blocking high-frequency noise currents while allowing DC or low-frequency signals to pass. They play a critical role in ensuring electromagnetic compatibility (EMC) in modern electronic systems, particularly in power supplies, communication interfaces, and industrial equipment.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
High-Frequency CMCs	Optimized for >1 MHz noise suppression	Switching power supplies, USB interfaces
Low-Frequency CMCs	Effective in 10 kHz 1 MHz range	Motor drives, industrial sensors
Multi-Winding CMCs	Multiple coils for differential/balanced circuits	Telecom transformers, Ethernet interfaces
SMD CMCs	Surface-mount design for compact PCB integration	Smartphones, IoT devices
High-Current CMCs	Rated for >10A continuous operation	EV charging stations, solar inverters

3. Structure and Composition

A typical CMC consists of: - Ferrite Core: Made of manganese-zinc (MnZn) or nickel-zinc (NiZn) materials for high permeability - Dual Windings: Symmetrically wound coils with equal turns to maintain signal integrity - Encapsulation: Flame-retardant epoxy resin for mechanical protection - Termination: Tin-plated copper leads or SMD pads

4. Key Technical Specifications

Parameter	Description	Importance
Inductance (H)	100 @ 100 MHz typical	Determines noise suppression effectiveness
Rated Current (A)	0.1 50 A DC	Prevents core saturation under load
Impedance Range	100 MHz 1 GHz	Defines operational frequency bandwidth
DC Resistance ( )	0.01 5	Affects power efficiency
Operating Temp ( C)	-55 to +150 C	Ensures reliability in harsh environments

5. Application Fields

Major industries include: - Consumer Electronics: Laptop chargers, smart TVs - Industrial Automation: PLC controllers, CNC machines - Medical Equipment: MRI scanners, patient monitors - Renewable Energy: Wind turbine inverters, battery storage systems - Telecommunications: 5G base stations, fiber optic transceivers

6. Leading Manufacturers and Products

Manufacturer	Product Series	Key Features
TDK Corporation	ACT1210 Series	1200 @ 100 MHz, 1.5 A rating
Sumida	CDRH3D28 Series	High saturation resistance for EV chargers
Coilcraft	114000C Series	AEC-Q200 qualified for automotive applications
W rth Elektronik	744210 Series	Compact SMD design for 10GbE interfaces

7. Selection Guidelines

Key considerations: 1. Match impedance curve with target noise frequency 2. Derate current capacity by 20% for safety margins 3. Choose SMD variants for automated PCB assembly 4. Verify temperature ratings for industrial applications 5. Prioritize AEC-Q qualified parts for automotive use

8. Industry Development Trends

Current trends include: - Miniaturization through advanced nanocrystalline cores - Integration with TVS diodes for combined EMI/surge protection - Development of 1000+ Amp CMCs for data center power systems - Adoption of RoHS-compliant materials - Implementation of embedded thermal sensors for smart monitoring

Application Case: A server power supply uses TDK ACT1210-600M CMC to suppress 150 MHz switching noise, achieving 40 dB reduction in conducted emissions.