INDUSTRY COMPONENT

Common Mode Choke

A common mode choke is an electromagnetic component that suppresses common mode noise in electronic circuits, particularly in Ethernet and communication systems.

View Specifications

Component Specifications

Definition
A common mode choke is a type of inductor designed with two or more windings on a single magnetic core. It functions as a filter to attenuate common mode electromagnetic interference (EMI) by presenting high impedance to common mode signals while allowing differential mode signals to pass with minimal loss. In Ethernet magnetics, it is integrated into transformers to provide noise suppression and signal integrity for data transmission over twisted-pair cables.
Working Principle
The common mode choke operates on the principle of mutual inductance. When common mode noise currents flow through the windings in the same direction, they generate magnetic fields that add up in the core, creating high impedance that blocks these unwanted signals. Differential mode signals (data signals) flow in opposite directions through the windings, causing their magnetic fields to cancel out, resulting in low impedance and allowing the signals to pass through unaffected.
Materials
Ferrite core (e.g., Mn-Zn or Ni-Zn ferrite), copper wire windings (typically enameled or insulated), and epoxy resin or plastic casing for protection.
Technical Parameters
ParameterTypical rangeNotes & selection driver
ImpedanceHigh at common mode frequencies (e.g., 100 Ω at 100 MHz)
InductanceTypically 100 μH to 10 mH
DC ResistanceLow, e.g., < 1 Ω
Current RatingUp to several amperes
Frequency Range1 MHz to 1 GHz
Operating Temperature-40°C to +125°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards
ISO 11801, DIN EN 50173

Parent Products

This component is used in the following industrial products

EMI Filter

A passive electronic component designed to suppress electromagnetic interference (EMI) in industrial electrical systems.

View Product Details

Ethernet Magnetics

Passive electronic component that provides electrical isolation, signal conditioning, and EMI filtering for Ethernet interfaces

View Product Details

Power Line Filter(s)

Electrical component that suppresses electromagnetic interference (EMI) and radio frequency interference (RFI) from power lines

View Product Details

Engineering Analysis

Risks & Mitigation
  • Overheating due to excessive current
  • Core saturation leading to loss of filtering effectiveness
  • Mechanical damage from vibration or shock
  • Degradation of insulation causing short circuits
FMEA Triads
Trigger: Excessive current or voltage spikes
Failure: Core saturation or thermal overload
Mitigation: Implement current limiting circuits, use chokes with higher current ratings, and ensure proper heat dissipation.
Trigger: Mechanical stress or environmental exposure
Failure: Cracked core or damaged windings
Mitigation: Use robust encapsulation materials, conduct vibration testing, and follow proper handling and installation procedures.
Trigger: Manufacturing defects in windings or core
Failure: Reduced inductance or increased DC resistance
Mitigation: Apply quality control measures, such as automated testing and inspection, and source components from certified suppliers.

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
Inductance tolerance typically ±20% to ±30%, depending on application requirements
Test Method
Testing per IEC 60950 for safety, and EMI/EMC testing per FCC Part 15 or CISPR 22 standards.

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
Verify equipment lists, process limits, capacity, and representative production evidence.
Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Common Mode Choke

Manufacturer profiles associated with Common Mode Choke.

Sourcing Common Mode Choke from China?
Tell us your specification and target quantity — we will match it against manufacturer records and come back with the factories that fit.
Request manufacturers We manufacture this

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Related Components

Dielectric Layer
Insulating layer in surface mount capacitors that stores electrical energy through polarization.
Optical Window
Transparent optical component for light transmission in polycarbonate lens housings
PCB Substrate
PCB substrate is the foundational insulating layer that provides mechanical support and electrical connectivity for electronic components in high-speed memory modules.
Edge Connector
Edge connector is a printed circuit board (PCB) connector that mates with the edge of another PCB, commonly used in high-speed memory modules for reliable electrical connections.

Frequently Asked Questions

What is the purpose of a common mode choke in Ethernet magnetics?

It suppresses common mode noise and electromagnetic interference (EMI) to ensure signal integrity and compliance with regulatory standards in Ethernet communication systems.

How does a common mode choke differ from a differential mode choke?

A common mode choke blocks noise currents flowing in the same direction on both conductors, while a differential mode choke attenuates noise currents flowing in opposite directions. Common mode chokes are often used in conjunction with differential mode filtering for comprehensive EMI suppression.

What materials are commonly used in common mode chokes?

Ferrite cores (such as Mn-Zn or Ni-Zn) for high permeability and frequency performance, and copper windings for low resistance and efficient current handling.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Request Manufacturing Insight for Common Mode Choke

Thank you. Your request has been sent. We'll respond within 1–3 business days.
Sorry, we couldn't send your message. Please try again, or email us at contact@cnfx.com.
Column Lines Communication Interface Chips
Get QuotesChat