{"id":4308,"date":"2026-08-24T12:09:54","date_gmt":"2026-08-24T12:09:54","guid":{"rendered":"https:\/\/theemcnews.co.uk\/?page_id=4308"},"modified":"2026-08-24T12:18:45","modified_gmt":"2026-08-24T12:18:45","slug":"tdkreleases","status":"publish","type":"page","link":"https:\/\/theemcnews.co.uk\/index.php\/tdkreleases\/","title":{"rendered":"TDK Releases SMD Common\u2011Mode Chokes for Compact High\u2011Current EMI Filtering"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"4308\" class=\"elementor elementor-4308\">\n\t\t\t\t<div class=\"elementor-element elementor-element-22c0e99 e-flex e-con-boxed e-con e-parent\" data-id=\"22c0e99\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-7bbc344 elementor-widget elementor-widget-image\" data-id=\"7bbc344\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"1920\" height=\"1080\" src=\"https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1.png\" class=\"attachment-full size-full wp-image-4242\" alt=\"\" srcset=\"https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1.png 1920w, https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1-300x169.png 300w, https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1-1024x576.png 1024w, https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1-768x432.png 768w, https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1-1536x864.png 1536w, https:\/\/theemcnews.co.uk\/wp-content\/uploads\/2026\/08\/9-1-600x338.png 600w\" sizes=\"(max-width: 1920px) 100vw, 1920px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-be24214 e-flex e-con-boxed e-con e-parent\" data-id=\"be24214\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2a07087 elementor-widget elementor-widget-text-editor\" data-id=\"2a07087\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p class=\"wp-block-paragraph\">TDK\u2019s new EP21 series SMD common\u2011mode chokes targets high\u2011current low\u2011voltage EMI filtering where PCB area and thermal performance are critical.<\/p><p class=\"wp-block-paragraph\">The flat\u2011wire double choke construction, underbody termination and four\u2011pin SMD design make these parts attractive for modern DC\u2011DC converters and compact EMC protection circuits according to the manufacturer press release.<\/p><h2 id=\"h-key-features-and-benefits\" class=\"wp-block-heading\">Key features and benefits<\/h2><ul class=\"wp-block-list\"><li><strong>High current handling<\/strong>\u00a0up to 35 A at low DC resistance, supporting high\u2011power DC\u2011DC stages without excessive conduction loss.<\/li><li><strong>Low DC resistance<\/strong>\u00a0down to 0.44 m\u03a9, helping reduce copper loss and ease thermal design in dense layouts.<\/li><li><strong>Wide inductance range<\/strong>\u00a0from 160 \u00b5H to 640 \u00b5H, allowing engineers to trade off impedance profile and current rating for different converter topologies.<\/li><li><strong>Flat\u2011wire winding on MnZn ferrite core<\/strong>, improving fill factor and thermal paths compared to classic round\u2011wire coils, with MnZn ferrite optimized for common\u2011mode suppression in the 100 kHz\u2013MHz range.<\/li><li><strong>SMD format with underbody termination<\/strong>, reducing footprint to 23.8 x 17.7 mm and simplifying automated assembly versus through\u2011hole chokes.<\/li><li><strong>Four\u2011pin design for mechanical robustness<\/strong>, providing stable solder joints and good coplanarity on the PCB, important for high\u2011mass magnetics in reflow processes.<\/li><li><strong>Impedance peak in the 500 kHz\u20133 MHz region<\/strong>, matching typical switching frequency bands and harmonics of modern DC\u2011DC converters and low\u2011voltage power electronics.<\/li><\/ul><h2 id=\"h-typical-applications\" class=\"wp-block-heading\">Typical applications<\/h2><p class=\"wp-block-paragraph\">The EP21\u00a0<a href=\"https:\/\/passive-components.eu\/toroids-and-current-compensated-chokes\/\" target=\"_blank\" rel=\"noreferrer noopener\">common mode choke<\/a>\u00a0series is aimed at common\u2011mode noise suppression in low\u2011voltage high\u2011current systems. Typical use cases include:<\/p><ul class=\"wp-block-list\"><li>Common\u2011mode input or output filters in non\u2011isolated DC\u2011DC converters (step\u2011down\/step\u2011up regulators).<\/li><li>EMC protection in low\u2011voltage power distribution rails in industrial and telecom equipment.<\/li><li>Common\u2011mode filtering on battery and DC bus connections in e\u2011mobility or robotics, where currents above 20 A are common.<\/li><li>Noise suppression on auxiliary low\u2011voltage supplies in larger power systems with fast power stages.<\/li><li>Compact common\u2011mode filtering in rack\u2011mount or module\u2011based PSU designs that need SMD assembly for high throughput.<\/li><\/ul><p class=\"wp-block-paragraph\">In practice, these chokes sit in series with both lines of a differential pair (for example, +V and return) and primarily attenuate common\u2011mode components while keeping differential\u2011mode impedance relatively low.<\/p><h2 id=\"h-technical-highlights\" class=\"wp-block-heading\">Technical highlights<\/h2><h3 id=\"h-electrical-ratings\" class=\"wp-block-heading\">Electrical ratings<\/h3><ul class=\"wp-block-list\"><li><strong>Rated voltage<\/strong>: 48 V AC and 80 V DC, suitable for typical low\u2011voltage DC buses (48 V telecom, 48 V industrial systems, higher\u2011current 24 V rails with transient margins).<\/li><li><strong>Rated current<\/strong>: 20.3 A to 35.0 A across the series, without derating up to +70 \u00b0C according to the manufacturer datasheet.<\/li><li><strong>Temperature behavior<\/strong>: No derating required up to +70 \u00b0C; above this point derating must be applied, which is important when placing the component near hot power devices.<\/li><li><strong>DC resistance (typical)<\/strong>: 0.44 m\u03a9 to 1.75 m\u03a9 across types, directly influencing I\u00b2R loss and temperature rise.<\/li><li><strong>Rated inductance<\/strong>: 160 \u00b5H to 640 \u00b5H per common\u2011mode winding, with average stray inductance down to 200 nH.<\/li><li><strong>Stray inductance (average)<\/strong>: 200 nH to 900 nH, indicating relatively low differential\u2011mode inductance so the choke primarily acts on common\u2011mode noise.<\/li><li><strong>Impedance peak frequency<\/strong>: Maximum impedance occurs between 500 kHz and 3 MHz depending on type, aligning with typical switching frequencies and their harmonics.<\/li><\/ul><h3 id=\"h-mechanical-and-construction-data\" class=\"wp-block-heading\">Mechanical and construction data<\/h3><ul class=\"wp-block-list\"><li><strong>Package format<\/strong>: SMD double choke with four pins.<\/li><li><strong>Footprint<\/strong>: 23.8 x 17.7 mm for all variants.<\/li><li><strong>Height<\/strong>: Between 21.6 mm and 22.3 mm, enabling relatively compact vertical integration compared with classic bobbin chokes.<\/li><li><strong>Underbody termination<\/strong>: Terminals located under the component body, minimizing lateral pad area and allowing dense placement.<\/li><li><strong>Core material<\/strong>: MnZn ferrite, a standard choice for power\/common\u2011mode inductors balancing permeability and loss at targeted frequency ranges.<\/li><li><strong>Winding technology<\/strong>: Flat\u2011wire, improving current density, lowering AC resistance and supporting better thermal paths than equivalent round\u2011wire designs.<\/li><li>\u00a0<\/li><\/ul><h3 id=\"h-ep21-series-overview-table\" class=\"wp-block-heading\">EP21 series overview table<\/h3><figure class=\"wp-block-table aligncenter\"><table><thead><tr><th>Ordering code<\/th><th>Rated current [A]<\/th><th>Inductance [\u00b5H]<\/th><th>DC resistance [m\u03a9]<\/th><th>Stray inductance (AVG) [nH]<\/th><th>Dimensions L x W x H [mm]<\/th><\/tr><\/thead><tbody><tr><td>B82552J2164J021<\/td><td>35.0<\/td><td>160<\/td><td>0.44<\/td><td>200<\/td><td>23.8 x 17.7 x 22.3<\/td><\/tr><tr><td>B82552J2284J021<\/td><td>30.8<\/td><td>280<\/td><td>0.80<\/td><td>390<\/td><td>23.8 x 17.7 x 21.9<\/td><\/tr><tr><td>B82552J2444J021<\/td><td>23.5<\/td><td>440<\/td><td>1.25<\/td><td>500<\/td><td>23.8 x 17.7 x 21.7<\/td><\/tr><tr><td>B82552J2644J021<\/td><td>20.3<\/td><td>640<\/td><td>1.75<\/td><td>900<\/td><td>23.8 x 17.7 x 21.6<\/td><\/tr><\/tbody><\/table><\/figure><p class=\"wp-block-paragraph\">This table illustrates the trade\u2011off between current rating, inductance and DC resistance: higher inductance variants provide more common\u2011mode impedance at lower frequencies at the expense of higher DC resistance and lower rated current.<\/p><h3 id=\"h-variant-selection-table-design-perspective\" class=\"wp-block-heading\">Variant selection table (design perspective)<\/h3><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Design priority<\/th><th>Recommended variants<\/th><th>Comment<\/th><\/tr><\/thead><tbody><tr><td>Maximum current, minimal loss<\/td><td>B82552J2164J021<\/td><td>Best suited for highest load currents and hot spots<\/td><\/tr><tr><td>Balanced current vs inductance<\/td><td>B82552J2284J021, B82552J2444J021<\/td><td>Good middle ground for typical DC\u2011DC converter rails<\/td><\/tr><tr><td>Highest common\u2011mode impedance<\/td><td>B82552J2644J021<\/td><td>For strongest suppression where current margin is available<\/td><\/tr><\/tbody><\/table><\/figure><p class=\"wp-block-paragraph\">This table is a qualitative indication based on the electrical data; final choice should be confirmed against the specific EMC and thermal requirements of the target design.<\/p><h2 id=\"h-design-in-notes-for-engineers\" class=\"wp-block-heading\">Design\u2011in notes for engineers<\/h2><ul class=\"wp-block-list\"><li><strong>Define noise profile first<\/strong>: Measure or simulate common\u2011mode noise spectra of the DC\u2011DC converter or power rail. Choose the EP21 variant whose impedance peak aligns with the dominant noise frequencies, keeping in mind that these parts peak between 500 kHz and 3 MHz.<\/li><li>\u00a0<\/li><li><strong>Check current and temperature margins<\/strong>: Use the rated current and DC resistance values to estimate conduction losses\u00a0P=I2\u22c5RP=I2\u22c5R and temperature rise at full load. Ensure operation within the no\u2011derating region up to +70 \u00b0C or apply appropriate derating curves from the manufacturer datasheet for higher ambient temperatures.<\/li><li>\u00a0<\/li><li><strong>Place carefully in the layout<\/strong>: Given the height and mass of the EP21 components, ensure solid pad design, sufficient solder fillet and mechanical support, especially in applications subject to vibration or shock.<\/li><li>\u00a0<\/li><li><strong>Consider stray inductance impact<\/strong>: While stray inductance is relatively low, it can still introduce differential\u2011mode impedance at high frequencies. In fast\u2011edge digital or very low\u2011voltage rails, verify that voltage drops and ringing remain acceptable.<\/li><li>\u00a0<\/li><li><strong>Combine with differential\u2011mode elements where needed<\/strong>: Common\u2011mode chokes often work together with X\/Y capacitors or dedicated differential\u2011mode inductors. The EP21 series provides the common\u2011mode element; overall EMC performance depends on the complete filter design.<\/li><li>\u00a0<\/li><li><strong>Account for underbody termination during PCB design<\/strong>: Ensure correct land pattern as specified in the datasheet so that the underbody contacts wet properly and solder inspection is feasible. Pay attention to solder mask definition and stencil thickness.<\/li><li>\u00a0<\/li><li><strong>Verify creepage and clearance<\/strong>: While these components are intended for low\u2011voltage applications, it is still essential to check creepage\/clearance distances and insulation specifications according to the applicable standards for the end equipment.<\/li><li>\u00a0<\/li><li><strong>Use manufacturer tools and data<\/strong>: TDK\u2019s design tools and product catalog entries can help refine the choice of part number, especially when optimizing for EMC compliance in complex systems.<\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>TDK\u2019s new EP21 series SMD common\u2011mode chokes targets high\u2011current low\u2011voltage EMI filtering where PCB area and thermal performance are critical. The flat\u2011wire double choke construction, underbody termination and four\u2011pin SMD design make these parts attractive for modern DC\u2011DC converters and compact EMC protection circuits according to the manufacturer press release.&hellip; <\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"footnotes":""},"class_list":["post-4308","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/4308","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=4308"}],"version-history":[{"count":4,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/4308\/revisions"}],"predecessor-version":[{"id":4312,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/4308\/revisions\/4312"}],"wp:attachment":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=4308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}