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Design Talk - Chips and DIPs

Mon, 06/01/2009 - 11:57am
poe, ehternet, power, transformer, REACH

Amit Gattani AkrosHigh Speed Digital Isolation In PoE+
Amit Gattani, Akros Silicon, www.akrossilicon.com

The new IEEE 802.3at standard is best known for its expansion of the powered device (PD) maximum power to 25.5 W from the 13 W “.af” level. Perhaps more significant, however, is the added control functions included in the standard that allows for dynamic allocation of power from the power sourcing equipment (PSE) to the network of powered devices. Dynamic and intelligent power allocation makes it possible to manage power over the network much in the same way as bandwidth is now managed. But to take full advantage of this new standard, it is necessary to acquire realtime power usage data from the primary side of each PD and transmit this information back to the PSE over the Ethernet data-link layer packets. AS1854

A high-speed digital isolation barrier integrated into the new Akros Silicon AS18x4 system-on-a-chip (SoC) offers designers an alternative to multichip solutions and eliminates the need for discrete optocouplers. By providing a multichannel, multi-megabit, high-isolation (>2KV) GreenEdge interface between the high and low sides, the AS18x4’s HV isolated ADC can provide live monitoring and input power profiling data feedback to the PSE. This feedback delivers valuable information to the PSE, including actual PD power requirements and actual cable loss. Static systems must use maximum possible numbers regardless of the actual power required or the actual cable distance.

As a consequence, a typical PSE switch will be limited either in the number of ports it can support or use a larger and less-efficient power supply. In contrast, by fully utilizing the AS18x4 real time monitoring capabilities in conjunction with the new standard, a typical 48-port PSE switch will be able to support PoE power on all ports with over 20 percent reduction in the PSE power supply. Now PSEs can do dynamic power allocation between various ports to provide better quality of service while reducing power supply cost and associated heat generation.

The typical PoE PD requires several regulated voltages The DigitalEdge isolation barrier of the AS18x4 also provides cross-isolation DC/DC timing management and control, thus improving efficiency and EMC performance over light load to full load conditions.  

Transformer Basics
By Steven Ensign, PowerVolt, www.powervolt.com

In customer transformer specifications, it is frequently assumed that the transformer will operate at 60Hz, and Ensign often must ask if the customer also requires 50Hz operation.  This is more than simply our version of, "Do you want fries with that?"  Whether to include or exclude 50Hz impacts the transformer's performance as well as its cost.  Sometimes it also determines the degree of safety the transformer can provide. 
Here's why:
Back in high school physics class we observed the circular patterns, called "magnetic Flux lines", made by sprinkling iron filings over a magnet.  An energized transformer is an electromagnet and therefore
creates similar magnetic flux line patterns. When dealing with flux lines and transformers, two laws of physics are particularly significant: 1) each magnetic material has a limit on how many flux lines it can handle, and 2) the lower the operating frequency the more flux lines that are generated.  Operating a transformer at 50Hz generates 20% more flux lines than at 60Hz.  As the number of flux lines approaches the magnetic material's limit, the heat in both the magnetic core and the internal coil wires increases, and under certain circumstances, unpredictably so.  This can result in a transformer that exceeds safe temperature levels.  Therefore, a transformer designed to run at 50Hz will simply run cooler at 60Hz.  But one designed only for 60Hz may overheat at 50Hz.
In order to accommodate 50Hz operation, the transformer must employ a magnetic core material that can handle the added flux lines.  Such materials are readily available, but they are significantly more costly than the "normal" core materials.  Using high-grade core materials when they are not required results in transformers that are over-designed & not competitively priced.
So, if a transformer will ever see 50Hz (for the European, South American, UK, or Japanese markets, for example), the capability to do so must be designed in from the beginning.  But if it will not see 50Hz, there is no sense in adding the unnecessary cost.

reach SimpsonREACH and the Electronics Industry
By C. Simpson

Certain chemical substances contained in electronic products and their components will need to be registered under the new EU Chemicals legislation (‘REACH’).

Pre-Registration

An essential first step for companies was pre-registration of substances in their electronic products by 1 December 2008 in order to benefit from extended registration deadlines (the first being 30 November 2010) during which they may continue to market their products in the EU.

Companies which missed the December deadline must suspend sales of their products to the EU until submission of a Registration dossier.

Companies can pre-register after the 1 December 2008 deadline in limited circumstances only. 

Registration

Failure by EU based manufacturers or importers, or EU based agents of non-EU suppliers, to register certain substances contained in electronic products in volumes of one metric tonne or higher with the European Chemicals Agency (ECHA) closes EU markets for those components.  For electronic products regarded as ‘articles’ (finished products) under REACH, this obligation applies only to substances intended to be released under normal or reasonably foreseeable conditions of use.

Most EU Member States have already adopted national rules on sanctions (from fines and market withdrawal to criminal penalties) for non-compliance with REACH. Equally, business customers and consumers are demanding proof of REACH compliance.

Post Pre-Registration

The next steps to ensure compliance under REACH post pre-registration are significantly more complex and require not only technical skills but also substantial legal advice, supply chain management and adjustments in logistics. Compliance has financial consequences that need to be carefully managed.

(1) Being properly represented
Non-EU companies need to review their Only Representative’s qualifications to ensure that those which were able to handle the Pre-Registration requirements are equally equipped to take forward the more complex Registration procedures.

(2) Notification of SVHCs
In certain circumstances, so-called “substances of very high concern” (SVHCs) included in a Candidate List of substances requiring authorisation and present in articles will need to be notified to ECHA from certain dates (June 2011 onwards).

(3) Supply chain communications
Suppliers of articles containing Substances of Very High Concern (“SVHCs”) included in the Candidate List must forward information on these substances, if contained above a concentration of 0.1% w/w, to the industrial or professional user (or distributor) being supplied with the article. Consumer requests for such information will have to be responded to free of charge within 45 days.

(4) Cooperation with competitors and anti-trust compliance
Companies having Pre-Registered a substance are required to organize themselves to provide or generate the data required for Registration in a Substance Information Exchange Forum (“SIEF”). The immediate priority will be for them to agree on the “sameness” (that the substances from different sources have the same chemical composition and hazard profile). Companies may also find it advantageous to participate in voluntary consortia to coordinate REACH compliance. Members need to ensure that their interaction in SIEFs or consortia does not result in any infringement of competition rules.

(5) Establishing ground rules
Legal agreements will need to be drafted concerning consortia, confidentiality, data licensing, data cost-sharing and work with contract laboratories etc.

(6) Managing data
A secure IT system for management of a company’s complete compliance activities is required or else the task will quickly become overwhelming.

(7) Product defence:
REACH has sparked significant pressures to defend substances appearing on the Candidate List or subject to restrictions against de-selection by the market, perhaps fuelled by NGO action. Constructive interaction with policy makers and management of supply chain relationships will be a necessary part of protecting markets.

The importance of successful company compliance

There is a very short window of opportunity for electronics companies to take stock and organize themselves to deal with the challenges which REACH raises. Continued EU market access is at stake – not only from a regulatory perspective but also in terms of the broader commercial environment.

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