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AC-DC Power Filters That Amplify Electronics Performance at Lower Cost

March 31, 2019 by Biljana Ognenova

It’s common to face at least a few, if not an array of typical problems with electrical circuit performance. Electromagnetic interference (EMI) is just one we point out as a common issue of poor-performing power circuits that in turn affects the components of the electronic device they belong to.

Since no manufacturer wants to see its devices performing below average or cause potentially hazardous situations due to power sags and dips or overloading, it’s important to carefully select power filters that alleviate EMI issues and guard against electricity risks.

There are thousands of various power line filters on the market that can be used as an effective solution to degraded circuit performance, protection against outside interference, for instance—cellular networks or lightning—or other unwanted electrical signals that cause problems with audio electronics or radio communications.

Of course, it is critical that AC-DC, EMI/EMC or RFI filters eliminate noise from high-frequency sources, but this process must be done in line with a number of local and international regulatory standards.

How can you tell what’s the best for various market standards, not overly expensive, yet robust filter, for the component you’re designing? Diligently looking into the perks of each of them is a wise course of action.

To help you narrow down choices, we take a look at some of the recently available filters on the market, including CUI’s latest AC-DC power filters from EMC-30 and EMC-20 series, as well as similar components from TDK Lambda and Schaffner.

CUI EMC-30 and EMC-20 Power Filters Provide Surge Compliance

Due to its extended range in power from 1W to 12,000 W, CUI is well known for helping designers create energy efficient products for diverse applications. Both products belong to the CUI low-power embedded AC-DC power supplies.

EMC-20 Series and EMC-30 Series power line filters: Image courtesy of CUI.

This EMC series is made of black flame-retardant heat-proof epoxy resin.

Configurations/fixture: embedded, available as board mount, chassis mount, and DIN rail, weighing 50g, 70g, and 90 g for EMC-30 series; and 20g, 40g, and 60g for EMC-20 series respectively.

Standards compliance: aptly named EMC-30 and EMC-20 power filter ensure EMC compliance with the IEC/EN61000-4-5 standard.  

Important product parameters: 20dB and 30dB noise filtering at 150 kHz ~ 1 GHz.

Price: $6.95 per unit at 500 pcs (wholesale distribution pricing).

Benefits: widely applicable modular solution because of the wide range voltage range (from 85 to 305 Vac) and superb noise filtering, in partially protected and fully protected environments, often in need of closed room protection, as well as being sturdy enough to manage wider temperature differences, heavy inductive loads, and lightning transients. Stricter CISPR22/EN55022 Class B limit requirements make them convenient for home devices, such as personal computers, because they are most likely to suffer from interference from closely placed radio or TV receivers.

TDK Lambda SIFI Series-2 Line EMC Filters for Standard and Medical Testing Devices

Available in small-sized, compact packaging to enable smooth deployment in medical and testing devices, SIFI-F, -G, and, -H filters minimise normal, enhanced, and very high insertion loss (IL) and leakage current.

Epcos SIFI-F Series filter. Image courtesy of TDK Electronics.

Configurations/fixture: compact, with push-on and screw terminal connectors.

Standards compliance: ENEC (regulatory standards for the European market), CSA (the joint standard-setting authority for Canada, the U.S., and Europe); and UL (international audit, certification, and verification association).

Important product parameters: 3A to 36A, 250VDC/AC-rated.

Price: product series range from approximately $13.62 to $32.19 per unit at 100 pcs (via distributors).

Benefits: general industrial application to the highest safety levels, meeting the environmental testing standard IEC 60068-1 with a climactic category of 25/100/21, SIFI filters come in a significantly smaller size than the average comparable products from competitors, which makes them convenient for medical device application.

Schaffner Single-Phase Filters for Wide Industrial Use

Schaffner’s solutions for combating EMI come in several filter series, including the presently chosen FN single-phase filters in FN2060, FN2070, FN2080, and FN2090 Series, available in single-stage, two-stage, and three-stage variants with general purpose, multi-stage, and high-performance attenuation.

Schaffner FN2080 Series EMC/EMI power filter. Image courtesy of Schaffner.

Configurations/fixture: Fast and easy chassis mounting.

Standards compliance: UL 1283, CSA 22.2 No. 8 1986, IEC/EN 60939 (applies to AC and DC applications). FN2090 has Z type surge pulse protection that enables compliance to IEC61000-4-5.

Important product parameters: 1A to 36 A, 50/60 Hz; 250 VDC/VAC, DC to 400Hz. operating frequency, and a temperature range from −25°C to +100°C (25/100/21).

Price: $23.40 per unit for the FN2080 Series, available via distributors.

Benefits: a variety of applications in electrical and electronic equipment for consumer goods, households, and industrial machinery, particularly contributive to electronic data processing, office automation and noisy environments in need of high filtering. FN Series vary in size from 0.7 mm to 156 mm, and can, therefore, enable great noise reduction for tiny components.

Although they come at different prices due to different materials and applications, all of these recent models of power line filters can help you design electronics while controlling conducted and radiated emissions and blocking high-frequency noise in demanding environments.

Depending on what is most important in your design—cost, compliance, or safety, it’s important to invest more if you want to meet regulatory standards.

But specific applications can be handled at a fraction of the cost, and, therefore, it’s worth dedicating more time to picking the right component.

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