The PMBus Forum continues to steer the Industry

Author:
Ira Sabran for PMBus

Date
09/24/2014

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Sabran for PMBus

Back in 2004, Bob White proposed the PMBus™ (Power Management Bus) digital power management protocol, the first open standard for commercial power supply manufacturers. The PMBus protocol allowed equipment manufacturers to standardize the use of digital signaling for controlling, configuring and monitoring power supplies. Operating over a serial bus, the PMBus protocol is organized in two sections.

The first, called Part I, described a transport mechanism to deliver instructions from one device to one or more receiving devices. The second, Part II, provided an extensive command language that translated the specific instructions. Six months after White’s initial proposal, working with the System Management Interface Forum (SMIF), PMBus’ specification working group released Version 1.0 of the PMBus specifications in March of 2005.

The original PMBus adopters consisted of grassroots volunteers from a handful of companies that each shared Bob White’s vision. Some of the original PMBus adopter companies included Texas Instruments, Tyco Power, Zilker Labs, Microchip Technology, Primarion, and Artesyn Technologies. Their combined efforts provided the groundwork for PMBus, which is now the primary digital power management protocol used by commercial power supply manufacturers.

Ten years after its inception, the PMBus forum consists of almost 40 adopters that have formally adopted the PMBus specifications. The organization’s specification working group still consists of volunteers from the adopter companies. In the interim, the specifications have evolved and have been enhanced significantly to its present form, Version 1.3 with Adaptive Voltage Scaling (AVS).

The primary enhancements of V 1.3 include increasing the communication speed from 400 kHz to 1 MHz to reduce latencies, a dedicated AVS bus that statically and dynamically controls processor voltages, and a host of general enhancements and improvements from the most recent version 1.2. Now processors, ASICs and FPGAs are able to optimize their performance and reduce their energy consumption by varying their operating voltage, using the minimum voltage needed at the required clock frequency. Standardizing the energy optimization method provides adoption opportunities and reduced energy consumption for computers, networking and telecom systems.

The advent of PMBus specification V 1.3 with AVS now provides opportunities for system manufacturers to build more efficient equipment that consumes less energy. Becoming a PMBus adopter is a key step toward leveraging the benefits associated with specification V 1.3 as well as influencing future direction. The PMBus Forum not only provides the vision for the power management industry but also the enabling tools.

The aforementioned developments have contributed to the success of the PMBus forum and its ability to carry out its mission of providing a standard designed to “…make the world more energy efficient, one power supply at a time.”

As a collateral benefit for PMBus adopters, the organization has just re-launched their website which provides adopters with an additional location to list/promote their PMBus-compliant products and to serve as an industry resource for power design engineers.  The PMBus V 1.3 specification is freely available to PMBus adopters in good standing from the PMBus website, and to all others upon formal request.

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