August 25, 2008

First Generic Power Supply Standard

Despite the fact that practically every electronic device needs a power supply unit (PSU), its requirements have not yet been standardized. Although some industries do have power supply standards (such as PICMG spec 2.11 for CompactPCI Power Interface and Power Supply Design Guide for Desktop PCs), these standards are for specific applications and do not have general usage.

IPC standard IPC-9592 is the electronic industry's first attempt to come up with a generic power conversion standard. The draft was initially developed by the IPC Power Conversion Subcommittee that included Dell, IBM, Lenovo, Hewlett Packard, Cisco Systems, Alcatel Lucent and Apple. This document standardizes the performance parameters for power conversion devices for various applications such as computers and telecommunications. It sets the requirements for design, qualification and conformance testing, manufacturing quality processes, and regulatory requirements. The document particularly lists applicable EMI standards and provides components derating guidelines. Although this standard is not mandatory (just like all IPC standards), due to the participation and support of major power supply users, one can expect its widespread acceptance.

In preparation for the standard release, IPC is planning a conference on November 6, in Irving, Texas, to discuss the details of the specification and outline the ideas that went into developing this standard.

Note that unlike Intel's Computer PSU Guides, IPC-9592 does not include any functional requirements such as voltages, currents, timing, connectors, etc. This is actually good for us, power supply designers. If our fellow digital engineers and system integrators would come up with a scalable power supply standard and would design their systems around standard PSU "bricks", OEM power supplies would become a commodity and would be primarily designed and built in the Far East. As a result, many of us designers, would have to become salespersons. But for as long as our fellow engineers choose to design their systems the way they please and then look for a custom PSU because their electrical and mechanical requirements can't be satisfied by off-the-shelf models, we, designers are in business. (-:

February 21, 2008

Efficiency Standards for Power Adapters

In a previous post I wrote about various programs and regulations aimed at increasing PSU efficiency.

Here is a brief update. On December 19th, 2007, the Energy Independence and Security Act of 2007 (EISA 2007) that is intended to reduce US Oil Dependence, became law. Although the act is aimed mainly at improving vehicles fuel economy and increasing the production of clean renewable fuels, it contain sections that affect power supplies.
Particularly, Section 301 External Power Supply Efficiency Standards establishes energy conservation standards that take effect on July 1, 2008 for so called “Class A External Power Supplies,” and establishes the processes to review and possibly amend those standards.
The term "class A external power supply' means basically a single output low-voltage AC-AC or AC-DC converter under 250W that is intended to be used with a separate end-use product.
According to this law, a class A external power supply manufactured on or after July 1, 2008 should meet specific efficiency standards depending on its nameplate power Po. For example, in the power range from 1 to 51 W [which is typical for most adapters] if you convert EISA requirement into percentage, the minimum efficiency in active mode should be 50% + 9*Ln(Po), where Ln(Po) is natural logarithm of the nameplate output power.

EISA 2007 requires US Depratment of Energy to issue a final rule prescribing energy conservation standards for battery chargers, if technologically feasible and economically justified, by July 1, 2011. DOE will also have to complete the determination on non-Class A external power supplies by a new deadline of December 19, 2009.

Note that unlike voluntary Energy Star® and 80 PlUS® programs, the above requirements are mandatory.