Secondary Windings: Frequency Range 1-100MHz

Component Specifications

Definition

Secondary windings in Ethernet magnetics are precisely wound conductive coils that form part of a transformer or common-mode choke. They function to transfer electrical signals between isolated circuits while providing electromagnetic interference (EMI) suppression and impedance matching required for reliable high-speed data transmission in Ethernet networks. These windings are typically designed with specific turn ratios and winding configurations to meet IEEE 802.3 standards for Ethernet communication.

Working Principle

Secondary windings operate on electromagnetic induction principles. When alternating current flows through the primary winding, it creates a varying magnetic field that induces a proportional voltage in the secondary winding. This provides galvanic isolation between network devices while maintaining signal integrity. The winding design ensures proper impedance matching (typically 100Ω differential) and common-mode noise rejection for Ethernet signals.

Materials

Copper magnet wire (typically 38-44 AWG) with polyurethane or polyamide-imide insulation, wound on ferrite cores (Mn-Zn or Ni-Zn compositions). Termination materials include tin-plated copper alloy leads or solderable pads.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Impedance	100Ω differential
Inductance	350μH minimum
Turn Ratio	1:1 or 1:1.5 typical
DC Resistance	0.2-0.5Ω typical
Frequency Range	1-100MHz
Isolation Voltage	1500V RMS minimum

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, IEC 60950-1, IEEE 802.3, UL 60950

Parent Products

This component is used in the following industrial products

Ethernet Magnetics

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

View Product Details

Engineering Analysis

Risks & Mitigation

Insulation breakdown due to voltage spikes
Impedance mismatch causing signal reflection
Saturation from DC bias currents
Thermal degradation from prolonged operation

FMEA Triads

Trigger: Insufficient insulation between winding layers
Failure: Short circuit between turns leading to signal loss
Mitigation: Implement automated optical inspection during manufacturing and 100% Hi-pot testing

Trigger: Improper winding tension during manufacturing
Failure: Variation in inductance values affecting impedance matching
Mitigation: Use servo-controlled winding machines with tension feedback systems

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Inductance ±20%, DC resistance ±10%, impedance ±15%

Test Method

LCR meter measurements at 1MHz, Hi-pot testing at 1500VAC for 60 seconds, network analyzer impedance verification

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

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Inspection readiness

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Supplier transparency

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Manufacturers of Secondary Windings

Manufacturer profiles associated with Secondary Windings.

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Frequently Asked Questions

What is the purpose of secondary windings in Ethernet magnetics?

Secondary windings provide electrical isolation between network devices, prevent ground loops, suppress electromagnetic interference, and ensure proper impedance matching for reliable data transmission.

How do secondary windings differ from primary windings in Ethernet magnetics?

While both windings share similar construction, secondary windings are on the isolated side of the transformer and are designed with specific turn ratios and winding configurations to provide the required isolation and impedance characteristics for the connected network equipment.

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.

Secondary Windings