PowerSource

Jun 16 2006 10:40AM | Permalink | Email this | Comments (4) |
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What's going on in the world of IC/instrumentation/sensor buses? For years – so many years, in fact, that the patent license has expired – I²C was the most commonly used bus for shuttling information around concerning how things were going on your motherboard. The 2-wire bus, developed by Philips for intra-chip communication, serves as the basis for the SMBus (System Management Bus) and the PMBus (Power Management Bus) and is generally offered on most chips more complex than a flip-flop (slight exaggeration).

Last month Philips announced a New Improved I²C bus called Fm+ (fast-mode-plus) that allows a top speed of 1MHz, a boost over the old max of 400kHz (which was more commonly operated at 100 KHz). Other boosts include device ID and a 10x-greater bus-drive capability of 4000pf. The basic I²C patent expired in August of 2004, and Fm+ is not covered by a patent. Philips cites LEDs and architectural lighting as examples of "emerging applications in LED and architectural lighting and gaming, which require a larger number of components on a single bus."

Hot on the heels of Philips' announcement is ADI's announcement of their partnering with Intel on a whole newbus, "a new way to efficiently communicate computer system heat dissipation and voltage management and control information…", called the Simple Serial Transfer (SST) Bus. SST also has a top speed of 1MHz. ADI has also introduced a family of digital temperature and voltage sensors for use in desktop computers and workstations, the ADT748x series. ADI claims SST trounces the old I2C bus in reliability, claiming "the SMBus measures about one error every 10,000 bits, compared to the SST bus' one error for every one billion bits processed." (ADI hasn't made any comparisons with the new Fm+ bus.)

But other than shuttling around sensor data quickly and efficiently, what else happens when Intel stamps its mark of approval on a new on-board bus? Chris Ambarian, senior analyst for iSuppli, sees more: "I would be willing to bet that Intel is planning to use this bus to put together a power management subsystem --certainly within their server products, and perhaps even within the bulk of their laptop motherboards -- to squeeze the maximum efficiency and reliability out of their systems.And since they've announced it publicly, they will probably do this within a relatively near term horizon.If so, this is a major tipping point:all those digitalized-power naysayers who said it will never go mainstream are soon going to be eating some humble pie.This has digitalized POS [power operating system] written all over it."

And how about SMBUs, and by extension, PMBus? To be continued…