www.coilcraft.com Open in urlscan Pro
2606:4700:10::6814:965  Public Scan

Form analysis
3 forms found in the DOM

POST /en-us/account/setlocals/

<form action="/en-us/account/setlocals/" method="post"> <input type="hidden" value="/en-us/edu/series/a-guide-to-coupled-inductors/?utm_source=Newsletter&amp;utm_medium=Email&amp;utm_campaign=PersonifAI_Newsletter" name="returnUrl">
  <div class="hd-settings_grid">
    <div class="hd-settings_cell">
      <h5>Warehouses</h5>
      <div class="cc-formGrid">
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="company-setting-15" name="SelectedCompany" type="radio" class="cc-input_radio" value="15" data-currencies="USD,EUR,GBP" checked="checked/">
          <label class="cc-label" for="company-setting-15"> UK Warehouse </label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="company-setting-1" name="SelectedCompany" type="radio" class="cc-input_radio" value="1" data-currencies="USD">
          <label class="cc-label" for="company-setting-1"> US Warehouse </label>
        </div>
      </div>
    </div>
    <div class="hd-settings_cell">
      <h5>Language settings</h5>
      <div class="cc-formGrid">
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="culture-setting-zh-cn" name="SelectedCulture" type="radio" class="cc-input_radio" value="zh-cn">
          <label class="cc-label" for="culture-setting-zh-cn">Chinese</label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="culture-setting-en-us" name="SelectedCulture" type="radio" class="cc-input_radio" value="en-us" checked="checked/">
          <label class="cc-label" for="culture-setting-en-us">English</label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="culture-setting-de-de" name="SelectedCulture" type="radio" class="cc-input_radio" value="de-de">
          <label class="cc-label" for="culture-setting-de-de">German</label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="culture-setting-ja-jp" name="SelectedCulture" type="radio" class="cc-input_radio" value="ja-jp">
          <label class="cc-label" for="culture-setting-ja-jp">Japanese</label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="culture-setting-ko-kr" name="SelectedCulture" type="radio" class="cc-input_radio" value="ko-kr">
          <label class="cc-label" for="culture-setting-ko-kr">Korean</label>
        </div>
      </div>
    </div>
    <div class="hd-settings_cell">
      <h5>Currency settings</h5>
      <div class="cc-formGrid">
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="currency-setting-2" name="SelectedCurrency" type="radio" class="cc-input_radio" value="2" data-code="USD">
          <label class="cc-label" for="currency-setting-2"> $ <em>US Dollars</em>
          </label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="currency-setting-6" name="SelectedCurrency" type="radio" class="cc-input_radio" value="6" data-code="EUR" checked="checked/">
          <label class="cc-label" for="currency-setting-6"> € <em>Euro</em>
          </label>
        </div>
        <div class="cc-formCell cc-field--radio cc-formCell--spanAll">
          <input id="currency-setting-7" name="SelectedCurrency" type="radio" class="cc-input_radio" value="7" data-code="GBP">
          <label class="cc-label" for="currency-setting-7"> £ <em>Pound sterling</em>
          </label>
        </div>
      </div>
    </div>
  </div>
  <button class="cc-button--main cc-button--small" type="submit"> Apply </button>
</form>

GET /en-us/search/

<form action="/en-us/search/" class="js-seach-box-form hd-search hd-action_item" method="get">
  <div class="hd-search_inner">
    <input type="text" class="hd-search_input ui-autocomplete-input" name="q" id="js-hd-search-input" placeholder=" " data-url="/en-us/search/suggest/" autocomplete="off">
    <label class="hd-search_placeholder" for="js-hd-search-input"> Search Coilcraft </label>
    <button type="submit" id="search" class="hd-search_button cc-button--dark" aria-label="Product Search Submit">
      <span class="hd-search_icon">
        <svg class="cc-icon_search" alt="Search submit button icon" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
          <circle cx="11" cy="11" r="8"></circle>
          <line x1="21" y1="21" x2="16.65" y2="16.65"></line>
        </svg>
      </span>
    </button>
    <div class="hd-user_item hidden-tablet-down">
      <a href="/en-us/search/" class="hd-user_link cc-button--main cc-button--small">
                        <i class="cc-icon-search" aria-hidden="true" style="margin-left: 0; margin-right: 0.5em;"></i>
                        Parametric Search
                    </a>
    </div>
  </div>
</form>

POST /en-us/trackingconsent/accept/

<form action="/en-us/trackingconsent/accept/" data-ajax="true" data-ajax-method="POST" data-ajax-mode="replace-with" data-ajax-update="#js-cookie-consent-banner" id="form0" method="post"> <button type="submit" class="cc-button--icon">
    <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#fff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
      <line x1="18" y1="6" x2="6" y2="18"></line>
      <line x1="6" y1="6" x2="18" y2="18"></line>
    </svg>
  </button>
</form>

Text Content

 


SITE SETTINGS

WAREHOUSES

UK Warehouse
US Warehouse

LANGUAGE SETTINGS

Chinese
English
German
Japanese
Korean

CURRENCY SETTINGS

$ US Dollars
€ Euro
£ Pound sterling
Apply
Search Coilcraft
Parametric Search
Datasheet Index
My Account

0
Products
Products
Ask a Question View FAQs
Power
 * Shielded Inductors
   * Molded Inductor
   * Ferrite Drum / Sleeve
   * High Current Flat Wire
   * High Current Radial Lead / Toroid
   * High SRF Power Chip Inductors
 * Unshielded Inductors
   * Ferrite Drum Surface Mount
   * Radial Lead Through Hole
 * Coupled Inductors
   * 1:1 High Isolation Coupled
   * 1:1 Shielded Coupled
   * 1:1 Shielded Loosely Coupled
   * 1:1:1 Shielded Coupled
   * 1:N Shielded Coupled
 * Uncoupled Dual Inductor
 * See All

RF
 * Ceramic Core Chip Inductors
 * Ferrite Core Chip Inductors
 * Air Core Inductors
 * Conical/Broadband
 * RFID Inductors
 * Tunable RF Inductors
 * See All

Transformers
 * Power Transformers
   * Power Converter Transformers
   * No-opto Flyback
   * Power Over Ethernet
   * Current Sensing
   * Ultrasonic Sensing
   * Gate Drive
   * Isolation
   * Capacitor Charging
   * CCFL Transformers
   * Power Factor Transformers
   * Configurable Transformers
 * Planar Transformers
 * Wideband RF Transformers
 * See All

EMI
 * Wirewound Ferrite Beads
 * Data Line CM Chokes
 * Power Line CM Chokes
 * See All

Design Support Tools

Use our suite of tools to help select, analyze and compare inductors
See all tools
Parametric Search

View our list of inductors and filter results based on your exact parameters
Explore
Datasheets

Looking for a datasheet? Search by product and download a PDF
See the list

Design Tools

Automotive

Resources
Resources
Ask a Question View FAQs
Product Documentation
 * Application Notes
 * Datasheets
 * Product Catalogs
 * Video Library

Handling & Processing
 * Cleaning / Washing
 * Flux Selection
 * Soldering

Models & Layout Tools
 * 3D & 2D Mechanical Models
 * SPICE Models & S-parameters
 * Application Notes

Education
 * Educator Center
 * Student Center
 * Getting Started
 * eBooks

General
 * Designer Kits
 * Change Notices (sign up)
 * Critical Product Cross Reference
 * Lead Free Solutions
 * Non-magnetic Components
 * Ratings
 * Toroid Products
 * Ultrasonic
 * LED

Video Library
Cx Family Common Mode Chokes
0402CT Low Profile Chip Inductors
XAL7050 High-inductance Shielded Power Inductors
XGL4020 Ultra-low DCR Power Inductors
FREE Samples

Get free samples quickly - most orders ship the same day!
Order Now
Datasheets

Looking for a datasheet? Search by product and download a PDF.
See the list
Student Support

Learn more about magnetics, request free samples or ask our engineers a
question.
Get Support

Quality
Quality
Ask a Question View FAQs
Quality Certification
 * ISO / IATF certifications
 * Transparency in Supply Chains
 * Social Responsibility
 * Supplier Quality Manual

Material Certification
 * Conflict Metals Policy
 * REACH Statement
 * RoHS Solutions

Safety Certification
 * Flammability
 * Safety UL / CSA / IEC

Reliability
 * AEC-Q200 components
 * Counterfeit Components
 * Thermal Aging
 * FIT / MTBF (Failure Rate)

Handling / Processing
 * Date Codes
 * PCB Washing
 * Environmental policy


About
About
Ask a Question View FAQs
About
 * About Us

Careers
 * Current Openings

Locations
 * Sales Locations
 * Corporate Office

Resources
 * Terms & Conditions
 * Press Releases
 * Upcoming Events
 * Credit Application
 * Video Library


Careers

Contact

Price & Availability



A GUIDE TO COUPLED INDUCTORS


WHAT IS A COUPLED INDUCTOR?

A coupled inductor has two or more windings on a common core. Coupled inductors
function in dc-dc converters by transferring energy from one winding to the
other through the common core. They are available in many sizes, inductance
values, and current ratings and most are magnetically shielded for low
electromagnetic interference (EMI). The windings may have equal (1:1) or unequal
turns ratios (1:N). Due to widespread demand in a variety of circuits, many 1:1
and 1:N standard coupled inductors are readily available off-the-shelf.


WHAT ARE COMMON APPLICATIONS FOR COUPLED INDUCTORS?

Typical circuits using 1:N COUPLED INDUCTORS
Figure 1

Purpose-designed coupled inductors are used in a variety of power conversion
circuits such as flyback, SEPIC, Fly-Buck™, Cuk, ZETA and multi-phase
topologies. These voltage regulation circuits use coupled inductors to
efficiently provide the required output voltages, which may be stepped up or
down from the input. To do this, SEPIC and Zeta circuits use 1:1 coupled
inductors, whereas flyback and other circuits use 1:N inductors. In multi-phase
power converters, coupled inductors provide inherent ripple current cancelling
that is not provided by single inductors.

Typical circuits using 1:1 COUPLED INDUCTORS
Figure 2

You can connect coupled inductor windings in different configurations to serve
different purposes. The windings may be connected to circuits separately for use
as isolation transformers or as common mode chokes. You may also connect them in
series to achieve a higher inductance or for use as a tapped inductor. As the
use of standard coupled inductors has grown, Coilcraft datasheets now provide
application-specific characterizations to help designers select the best-suited
inductor.


WHAT IS THE DIFFERENCE BETWEEN A COUPLED INDUCTOR AND A TRANSFORMER?

There is often little or no physical difference between what one engineer calls
a coupled inductor and another calls a transformer. Both may have either a 1:1
or 1:N turns ratio and have similar winding-core arrangements, and they may even
"look the same." Actually, the most appropriate name depends on the intended
application.

Coupled inductors and flyback transformers both use cores to store energy
received from a winding and then transfer that energy to the other winding. For
both transformers and coupled inductors, the efficacy of the winding coupling,
expressed as coupling coefficient k, depends on the core material properties as
well as the physical arrangement of the windings and core.

Common to transformers and coupled inductors is the fact that close coupling
between the windings (k > 0.9) results in low leakage inductance and generally
provides the most efficient energy transfer and widest usable frequency
bandwidth. High-performance designs like Coilcraft's LPD and LPD-V families are
able to provide the desired coupling factor while also providing a high measure
of voltage isolation between windings.

Close coupling may not be optimal for all applications. In fact, Coilcraft's
MSC1278 Series of coupled inductors is designed with high leakage inductance for
use in certain SEPIC applications. The loosely coupled windings (K ≈ 0.8)
improve SEPIC efficiency by reducing circulating current and still provide twice
the ripple current reduction of separate inductors.

You can connect coupled inductor windings in different configurations to serve
different purposes. The windings may be connected to circuits separately for use
as isolation transformers or as common mode chokes. You may also connect them in
series to achieve a higher inductance or for use as a tapped inductor. As the
use of standard coupled inductors has grown, Coilcraft datasheets now provide
application-specific characterizations to help designers select the best-suited
inductor.


HOW DO I CHOOSE A COUPLED INDUCTOR?

Application-specific data for off-the-shelf coupled inductors
Figure 3

Selection of a coupled inductor is application-dependent. As shown in Figure 3,
Coilcraft datasheets characterize coupled inductors for multiple circuit uses,
and Coilcraft has developed online tools for selecting coupled inductors.

For a particular inductance and current rating, our Coupled Inductor Finder Tool
provides a list of off-the-shelf coupled inductors that meet those requirements.

This document describes the particular SEPIC calculations for determining the
required coupled inductance parameters.

Once the values are determined for your SEPIC application, enter those values
into the Coupled Inductor Finder tool to find and compare coupled inductors that
meet your requirements.

 


WHAT TYPES OF COUPLED INDUCTORS DOES COILCRAFT MANUFACTURE?

Coilcraft designs and manufactures a variety of surface mount coupled inductors
for many applications including, 1:1 low profile, low DCR, miniature, high
temperature, and high isolation alternatives. Coilcraft also offers various 1:N
coupled inductor alternatives in ratios from 1:1.5 up to 1:100.

 * View all of Coilcraft's surface mount coupled inductors
 * View visual selection guide showing Coilcraft 1:1 coupled inductors and
   typical application schematics
 * See Coilcraft's coupled inductors, such as LPD and MSD styles, that have been
   characterized as common mode chokes for < 1 GHz applications, as shown here.


RELATED APPLICATION NOTES

 * Selecting Coupled Inductors for SEPIC Applications
 * Offline Buck Converter with Tapped Inductor Offers Improved Performance – ON
   Semiconductor
 * Video - Shrink Your Fly-Buck Design with Off-the-Shelf Coupled Inductors –
   Texas Instruments
 * The Benefits of the Coupled Inductor Technology – Maxim Integrated
 * Coupled inductors broaden DC/DC converter usage – Texas Instruments

 


DESIGNER KIT'S

 * C463 – 41 "Essential" values from 10 LPD and MSD 1:1 series
 * C400 – MSD1278 series 1:1 with 29 values from 4.7 µH to 1000 µH


WHAT'S NEXT?

View more: Getting Started Series

 
 

EDUCATIONAL COURSES

 * A Guide to AEC-Q200 Qualified Components
 * A Guide to Coupled Inductors
 * A Guide to Flyback Transformers
 * A Guide to Forward-mode Transformers
 * A Guide to Gate Drive Transformers
 * A Guide to Understanding Common Mode Chokes
 * Magnetics for Power over Ethernet (PoE)
 * Understanding and Selecting Isolation Transformers
 * What is a Conical Inductor?
 * What is an Inductor?
 * What is an LC Filter?
 * Wirewound Ferrite Beads: Outperforming Traditional Chip Ferrite Beads

Products Power Inductors RF Inductors Transformers EMI Chokes/Wirewound Ferrite
Beads Design Tools DC-DC Optimizer Power Inductor Finder and Analyzer Coupled
Inductor Finder and Analyzer Current Transformer Finder DCR @ Temperature Tool
RF Inductor/Choke Finder and Analyzer Common Mode Choke Finder and Analyzer
Wirewound Ferrite Bead Finder and Analyzer Reference Design Inductor Finder See
All Design Tools Applications Automotive Ultrasonic Sensing LED Driver Coilcraft
Contact Careers Press Samples About Us View FAQs Privacy Policy Terms &
Conditions (US) Terms & Conditions (UK) Terms & Conditions (CN)
Locations
World Headquarters
Coilcraft Inc.
1102 Silver Lake Road
Cary, USA Illinois
Europe Headquarters
Coilcraft Europe
21 Napier Place
Wardpark North
Cumbernauld, United Kingdom
Asia Headquarters
Coilcraft Taiwan
3F, 91-2, Section 2
Chung-Yang Road, Tu-Cheng
Taipei Hsien, Taiwan Taipei City
Copyright 2022, Coilcraft, Inc.
Support
USA +1-800-322-2645
United Kingdom +44 1236 730595
Taiwan +886 2-2264 3646


We use essential and non-essential cookies on our Site, including third party
advertising cookies to provide tailored ads. For more details or to manage your
preferences, please see our Cookie Policy. By closing this banner, clicking or
continuing to browse this site, you agree to the use of cookies. Privacy Policy








WARNING


Close