Dave's powertrip #5: Time to refresh PMBus - Part I

Dave Freeman's Powertrip

Greetings TI E2E folks!

I invite you to join me on a trip as I ponder the past and contemplate the future of power and energy in the “Dave’s Powertrip” blog series. I’ll share my thoughts and invite you to do likewise.

Power to the people!

-Dave Freeman





"Time to refresh PMBus - Part I"

Just about every Sunday we have a catch up phone call with our daughters. This last Sunday, my youngest daughter was on a tirade about the wireless connectivity in her dorm. She moved in a week early after volunteering to be a Badger Buddy. The person in this position is required to help others move in later in the month. During that week of minimum occupancy, she became accustomed to very good wireless Internet connectivity. However, now with the dorm full, the Internet slowed down dramatically. She actually compared it to the connectivity at her grandmother’s house. In this case, dial-up Internet is the only way to connect a computer. Also there is very limited smartphone connectivity. In most cases, the phones are stuck on the sand bar, our name for that smallest bar displayed on the phone. I remind her that when visiting her grandmother, it is more about communicating with grandmother and less about the rest of the world. Her response typically is, “What do I do when granny is sleeping?”

Whether it is need or want, once you get used to high-speed connectivity that is always available, it is difficult to do without it. This brings me to the topic for this Powertrip: the physical layer of the power management bus (PMBus).

When early PMBus adopters were working through the initial definition of the PMBus, we decided to break the definition into two parts. Part I – General Requirements, Transport and Electrical Interface defines the physical layer. Part II – Command Language describes the commands and the data layer for the protocol. Revisions 1.0 of these specifications were released in March of 2005.

So why two parts? The physical layer, Part I, was a subject for a fair amount of debate and discussion. The conclusion was that whatever we decide, PMBus would evolve and would likely be different in the coming years. We also thought that Part II, the command and data layer, would not go through the same level of significant change. Read more of Dave's Powertrip #5 on EDN.


What ideas do you have to stay off the "sand bar?"



Index of all Power House blog posts.