SAE has developed a family of DC filters designed for use with industry-standard medium-power brick DC/DC convertors.
SAE has developed a family of DC filters designed for use with industry-standard medium-power brick DC/DC convertors. These filters have been designed for optimum performance in critical applications where FCC Part 15 or CISPR emissions compliance is required. The filters offer excellent common-mode and differential-mode filtering and allow power modules to meet FCC and EN55022 (CISPR22) requirements.

Electrical specifications include an isolation voltage for common mode 1500V DC and a rated differential input voltage of 75V DC.

The filters have a maximum differential input voltage 100V DC or peak and the operating case temperature is -40 to +100C.

The filters have certifications from UL, CSA and TUV and the calculated MTBF is 17Mh.

Power-related issues are frequently the cause of time outs, unexplained downtime and other commonplace system or networking glitches.
Data protection is a strange old subject. Companies spend a fortune on anti-virus software, intrusion detection systems, firewalls and spyware blockers. Yet according to W.

Curtis Preston, a data protection specialist at GlassHouse Technologies, most problems lie within - with over 80% of security leaks generated internally.

Similarly, when people think of preventing data loss due to power supply problems, they typically consider an uninterruptible power supply (UPS) or a surge suppressor.

Recent studies by Bell Laboratories, however, indicate that less that 4% of power-related problems would be addressed by such devices.

Thus even networks and computer systems that are well protected by UPSs and surge protectors are at serious risk.

‘Power problems caused by small surges, spikes and sags in the electricity supply cause 15 times more problems today than viruses’, says Bahram Mechanic, CEO of SmartPower Systems of Houston, Texas, a maker of power protection and conditioning equipment.

‘Servers, workstations and networking gear can best be protected by using transformer-based filters’.

‘Whereas old style power conditioners were large and expensive, a new breed of inexpensive electronic power conditioner is being deployed today in the computer room’.

Downtime causes millions of dollars in damage annually to computer networks around the globe.

In many cases, people attempting to troubleshoot the cause of downtime waste hours addressing the wrong problem.

They blame the software, the network, viruses, spyware and a host of other causes.

Sometimes they are correct and this resolves the problem.

Often, however, they are correcting the wrong problem.

Power-related issues, it turns out, are frequently the cause of time outs, unexplained downtime and other commonplace system or networking glitches.

Two major studies of power quality have been completed in recent years.

The first one, by Bell Labs, found the following areas accounted for most power-related issues: blackouts - 1.4%, surges higher than 200V - 2.4%, sags - 14% and surges less than 200V - 82.2%.

These results are confirmed by a similar study performed by IBM which found: blackouts - 0.5%, surges higher than 200V - 2%, sags - 10% and surges less than 200V - 87.5%.

Thus around 80 to 90% of the time, electronic equipment is being affected by tiny surges as opposed to lightening flashes or blackouts.

To make matters worse, these little spikes wreak havoc in terms of logic confusion, system errors and frozen screens.

‘Everyone has had their computer lock up on them’, says Anthony Loguidice, Assistant Vice President of Service for Sharp Electronics of Canada .

‘If there’s spikes and surges on the line it can cause quality issues and a lot of odd problems’.

The reason this situation has remained largely under the radar screen perhaps lies in the fact that there are actually two distinct types of spikes and surges.

Most people protect themselves against one (occurring in what is known as ‘normal mode’) but fail to pay any attention to the other (occurring in ‘common mode’).

Most electrical wiring inside any building has three wires: two wires that carry the power are called ‘hot’ and ‘neutral’; and a third typically green wire which is for safety and a logic reference point called the ‘ground’.

Normal mode power noise occurs between the hot wire and the neutral wire causing damage to power supplies, PC board blowouts and other catastrophic issues.

Common mode noise, on the other hand, occurs between the hot or neutral wire and the ground wire causing logic confusion, data loss, system errors, blue screens or mysterious service calls that end without an actual problem being located.

Relating this back to the two studies above, blackouts and large surges account for less than 5% of all power problems and happen in normal mode.

As these events are catastrophic, most people who have experienced one tend to deploy protection technology to guard against further normal mode hazards.

Yet 80 to 90% of all problems actually happen in common mode.

Although these events are usually not disastrous, they generate all kinds of mischief, consume end user time, result in data loss and generate a torrent of help desk traffic.

Microprocessors normally work with 5V DC (some of the newer models work with 2.7V DC, which makes them even more sensitive to small power anomalies).

In effect, they act as high-speed switches being turned on and off millions of times per second.

The off-state (0V) equates to the binary ‘0′ and the on state (5V) equates to ‘1′.

This gives you the foundation of the binary language (0100110010) by which computing functions.

‘Any spike greater than 1V confuses the logic - the microprocessor being read as a 1 rather than a 0′, says Mechanic.

‘The end result is screen lockups, time-outs or delays’.

But in this day and age, surely electrical wiring is such a precise science that such issues are minimised?

Not so.

Apart from the fact that the power coming in from the average utility is dirty - way below the level of stability required to safely run electronic equipment - many big cities suffer from decidedly poor wiring.

‘Surprisingly, the San Francisco Bay area has some of the worst wiring’, says Bob Schoon, President of Schoon Corporation, a copier-fax-printer business in San Leandro, California.

‘The neutral voltage there is always all over the map’.

What should be done, then, to better protect computer systems and networks?.

Let’s take a look at the pros and cons of the various options available on the market.

Surge suppressors or surge protectors are devices that protect equipment from excessive voltage (spikes and power surges) in the power line.

They divert power from the incoming hot line to the neutral and/or ground wires.

Alternatively, they can absorb the energy within the unit.

Surge protectors are relatively inexpensive and offer excellent protection against catastrophic high-voltage spikes in normal mode.

However, they fail to handle the relatively small over- and undervoltages that occur in common mode which momentarily disrupt computer networks.

As large scale normal mode surges account for only about 2% of all power problems, they are an incomplete solution.

A UPS is a backup power supply used when the main electrical feed has failed or drops to an unacceptable voltage level.

Small UPS Systems provide battery power for a few minutes.

This gives IT enough time to power down critical servers without suffering data loss - otherwise anything stored in RAM is lost during a blackout.

More sophisticated systems are tied to electrical generators so power is available for several days.

UPS systems can also include a surge suppressor.

UPSs should clearly be part of any power protection strategy.

But it has to be understood that blackouts make up around 1% of power quality situations.

Even if you include large sags (10-14% of the problems), you are still leaving over 80% of the power quality concerns untouched.

Isolation transformers (also known as line conditioners) have gained popularity in recent years.

A transformer changes one voltage to another and is made from two coils of wire close to each other (or wrapped around an metal core).

Power is fed into one coil to create a magnetic field.

The magnetic field causes current to flow in the other coil.

An isolation transformer uses this technology to prevent current from flowing directly from one side of a circuit to the other.

These devices are an excellent way to filter out normal mode voltage spikes (down to less than 10V) and common mode spikes (down to less than 0.5V).

On the downside, they are heavier and more expensive than more modern alternatives - costing about $1000 for a unit with adequate server protection.

Recent technological advancements in the field of power conditioning have now yielded devices that provide ‘computer grade’ power at the same price as limited-function surge protectors and a fraction of the price, weight and size of isolation transformers.

Known as transformer based filtering (TBF) devices, the latest circuits include transistors, thyristors, capacitors, and relays to handle power conditioning duties in tandem with a small transformer.

This intelligent digital circuitry provides greater functionality than a traditional line conditioner/isolation transformer.

TBF units provide basic protection against massive spikes up to 6000V as well as small common mode spikes and surges.

In addition, they constantly monitor the line power.

If voltage goes too high for more than five cycles (80ms), for instance, the motherboard could blow out.

The TBF cuts the power off to prevent damage to the machine.

Further, new TBF technology can identify miswired outlets.

If a ground wire is loose, or the polarity between neutral and hot is reversed, the device will not let the power reach the protected machine.

Prolonged overvoltage protection (POVP) is another feature built in to the device.

The loss of the neutral wire, for example, can lead the voltage to increase to the 160 to 200V range for an extended period of time.

A TBF unit disconnects the output to keep mission-critical systems safe.

SmartPower Systems’ TBF, for example, compresses all this functionality into a 480g package the size of handheld cassette tape recorder.

Built-in RJ11 and RJ45 connectors extend protection to telephone and network lines.

A 2005 research study by PowerCET Corp confirms that TBF technology matches and in some areas betters the performance of more expensive isolation transformers.

‘The SmartPower electronic power conditioner kept let-through voltages below 10V line/neutral and 0.5V neutral/ground’, says Thomas Shaughnessy, Vice President of Research at PowerCET, a Santa Clara, California-based power quality consulting firm.

‘The Smart Power products removed output power when applied voltages exceeded preset limits and automatically reset when applied voltage returned to normal levels’.

On one test, for example, surges of 3000V were used on a variety of isolation transforms as well as the TBF.

The results showed that TBF surge attenuation on common mode was less than 0.5V, the same as an isolation transformer.

Blackouts and line sags make it essential to protect servers, workstations and networking gear from electrical harm.

UPSs and surge suppressors offer safeguards against catastrophic events such as burned-out motherboards, and keep computers operating at least long enough to prevent data loss.

But these methods are not enough in a dirty-power environment as they fail to address power enemy number one - low voltage spikes.

That’s why isolation transformers or TBF units are required to cleanse the power coming along the utility line and take care of other low voltage factors.

Otherwise freezes, system hangs and data loss will result.

UPSs with TBF units are recommended as they are about half the price of a comparable UPS with line conditioner unit, and are much smaller and lighter.

SmartPower Systems offers a wide range of UPS with TBF products.

For those with UPS and surge suppressors already in place, TBF technology (model Smart Cord) can be added inexpensively to upgrade those units.

The WD range of toroidal inductors features good suppression performance at high frequencies, high overload capability, low flux-leakage and economical pricing.
A new range of differential-mode suppression chokes has been introduced by the Almag Division of Carnhill Transformers. This WD Range of toroidal inductors is based on iron powder cores, for good suppression performance at high frequencies, high overload capability, low flux-leakage and economical pricing. Included are 164 separate designs, with current ratings from 0.35 to 50A, inductance values up to 13mH and sizes ranging from 21 to 120mm diameter.

Vertical mounting bases are available for the smaller choke sizes, with the company’s custom epoxy potting available for the larger sizes to ease mounting and improve cooling.

REO has published a new 22-page guide to EMC filters and their application.
Selecting an EMC filter based on typical test house protocols employing a conventional 50ohm source and 50ohm load impedance test does not guarantee the connected product will not cause (or suffer) problems in the field due to conducted emissions (or susceptibility). According to REO UK, such tests only provide a rudimentary method of assessing the relative merits of one filter range against another. They do not provide an effective means of selecting a filter with the intention of ensuring compliance with EMC emission.

The test data should reflect a supply/load impedance mismatch, which is more typical of everyday operating conditions.

Furthermore, a better performance does not necessarily depend on the use of higher quality components, multiple stages and inherent, additional cost but it is more a question of careful design and manufacture.

With the electromagnetic (EM) spectrum becoming ever more densely populated due to the rapidly growing number of EM emitting devices (intentional and unintentional), that can both suffer from and generate EM noise, the selection of a correct filter for EMC (electromagnetic compatibility) has never been more important.

A new 22-page guide on EMC filters and their application has been just been published by REO.

It is available free on request or can be downloaded from the company’s website.

Topics covered include a definition of EMC, filters and their design, typical filter components, choke design and issues affecting filter performance.

New low profile surface mount inductors provide reliable protection against challenging EMI problems in high current applications.
With their powerful magnetic shield, the new low profile DR363 and DR364 Series surface mount inductors from Datatronic Distribution, provide reliable protection against challenging EMI problems in high current applications. The advanced surface mount DR363 and DR364 inductors are available in a wide range of inductance values. They feature a compact and economical design with a seated profile as low as only 3.0mm above the circuit board.

They are ideal for high-density circuit board designs.

Combining high-performance, economy and dependability, the DR363 and DR364 Series inductors provide EMI circuit protection for DC/DC convertors and DSC, DVC and PDAs.

Their small size makes them especially useful in handheld, portable or smaller equipment.

Depending on specific model, the DR363 and 364 Series inductors feature an inductance range from 2.0 to 150uH, with an operating frequency range from 10kHz to 1MHz, maximum DC resistance from 19.2 to 738ohm and a maximum current rating from 0.31 to 5.41A.

They operate over a wide temperature range from -20 to +85C and all materials meet UL94V0 requirements.

With a rugged design, the compact DR363 and DR364 Series inductors come in packages as small as 6.3 x 6.2mm.

Their flat top surface makes them compatible with high-speed pick-and-place assembly equipment, and they are also suitable for high-temperature soldering.

Custom designed DR363 and DR364 Series inductor packages can be specified to meet unique circuit requirements.

The DR363 and DR364 Series inductors are priced from $0.25 each in typical production volumes.

Lead-time is stock to six weeks.

Volume OEM pricing is available on request.

NIC Components Europe has made two significant updates to its website to provide improved support and rapid information for its customers.
NIC Components Europe has made two significant updates to its website to provide improved support and rapid information for its customers. The first enhancement is a linked site called ‘SMTmagnetics.com’ that gives detailed information about the company’s comprehensive range of surface mount chip and power inductor components. The second addition is a facility called ‘live help’ that is accessed via the website homepage.

Customers can use an instant messaging facility to converse directly with an NIC technical representative.

The ‘live help’ facility allows design engineers to quickly ascertain the ideal approach or component for their application.

The system gives an important improvement over the email enquiry systems offered by many companies as it is truly live.

This means that customers can gain almost instant answers and technical information.

A new range of surface mount EMI/RFI shield clips saves PCB space and reduces assembly and rework time by eliminating through hole manufacturing processes.
Harwin has introduced a new range of surface mount EMI/RFI shield clips which save PCB space and reduce assembly and rework time by eliminating through hole manufacturing processes. Explains Richard McDonnell Product Manager for the MIDI and Mini clips: ‘Traditional shielding cans are soldered to the board using through-hole technology’. ‘This is often performed after the main automated assembly process using manual secondary soldering operations’.

‘Not only is this process time consuming and costly but causes further difficulties should reworking become necessary’.

Supplied in industry standard tape and reel packaging, Harwin’s RFI shield clips are placed on the board and soldered using standard SMT placement equipment.

The shielding can is then fitted during final assembly within seconds.

As it is possible to remove and refit the can a number of times, tuning and rework operations are simplified.

Therefore both initial production and rework costs are significantly reduced.

The Midi RFI clip is designed for shielding cans using 0.3mm thick material: the Mini version is 40% smaller and is suitable for shield cans 0.13-0.23mm thick.

Clips are available in 100% tin plate.

The Midi clip is also available in a beryllium-free copper option, suiting it to applications covered by the WEEE (Waste Electrical and Electronic Equipment) and the End of Vehicle Life Directives.

Harwin’s EMI/RFI clips are targeted at telecomms basestations, radiocomms, data processing and in-car entertainment systems.

Previous devices have been successfully used in diverse applications such as the Bowman military radio project and automotive satnav/DVD players.

A new line of PC board shields allows electronic components to be shielded from the unwanted effects of EMI on the PCBs themselves.
A new line of PC board shields from electromagnetic interference (EMI) shielding specialist Laird Technologies allows electronic components to be shielded from the unwanted effects of EMI on the PCBs themselves. These PC board shields feature solid tops, scored to allow peel off when access to board level components within the can is required. This innovative peel-off feature prevents damage to the board and components by eliminating the need for labour intensive de-soldering.

Peeling off the lid is simply achieved by using a small starter hole for simple removal, the hand operation requiring only minimal force using a simple hook driver or tweezers.

The scored feature can be retrofitted so that it can be incorporated into existing designs of board level shielding.

This eliminates the need for costly miniature fence and lid designs necessary when occasional access to components is required.

The feature is an advance in board level shielding design, and it requires no changes in assembly techniques or normal SMT procedures.

Overall, the advantages of using Laird Technologies’ PC board shields can be summarised as: easy removal of the scored lid area; a simple replacement technique for the lids; there is no adverse effect on shielding effectiveness; and the shields can be used on either surface mount or through hole applications.

Moreover, the shields require no special tools or equipment, and only a very low force is required for lid removal.

Laird Technologies’ PC board shields retain all physical properties after PSMCIA/JEIDA testing for shock, bending, torque, drop, and vibration, and meet EIA and JEDEC specifications.

Custom sized configurations are available, and these versatile shields can be packed in tape and reel for SMT and pick and place applications, so that overall, the range of applications is wide.

P series power entry modules from Tyco Electronics are the first 10A devices to provide all five power entry functions in one small package.
Recently introduced P series of power entry modules (Chameleon modules) from Tyco Electronics are the first 10A devices to provide all five power entry functions in one small package. Chameleon modules offer increased design flexibility and readily adapt to their environment and the needs of international markets. Benefiting from a compact design and modular construction, Chameleon modules allow power entry features to be selected without altering the panel cutout.

With adapters the devices will fit any standard panel cutout.

Technical features of the Chameleon module range include snap-in or flange mounting, IEC powerline connector, both North American and European fusing capabilities, two voltage selections, optional DPST on/off switch and filtering options for general purpose, medical, and high-performance applications.

Chameleon power entry modules feature four filter options.

S models offer protection for general purpose applications where line-to-ground and line-to-line noise must be controlled.

H models provide susceptibility protection without leakage current associated with line-to-ground capacitors and allows equipment to meet UL544 for patient care and non-patient care products.

High performance filter versions (L models and Z models) are designed to help bring most digital equipment into compliance with EN55022, Level B conducted emissions limits, whereas L models also comply with medical standards UL544, UL2601 and EN60601.

In addition, an interconnection block (B models) is available for the Chameleon module range, reducing external wiring by connecting the voltage selection terminals of an unfiltered P series module with a switch and an IEC connector.

BFi Optilas is now offering automotive EMI ferrite solutions from Steward.
BFi Optilas is now offering automotive EMI ferrite solutions from Steward. As the use of sophisticated electronics in automobiles continues to grow at astounding rates, so does the issue of electromagnetic compatibility (EMC). In future generations, automotive systems that have traditionally been mechanical (accelerating, braking etc), will be replaced by electronic systems.

The electronics designer must account for both the radiation of and immunity to high frequency interference (RFI) from internal and external sources.

Steward’s soft ferrites offer effective and efficient EMI suppression solutions for automotive circuitry including: controller area networks, safety systems and DC motor applications.

Steward offers a complete line of products and materials to provide EMI solutions for low frequency, broadband and high frequency applications.