Design Article
Comment
Dr DSP
I would like to see a comparison between the Maxim/LTC parts and some of the ...
Rich Krajewski
Plus I liked Mr. Sanogo's shirt.
Hot-swapping: from “band aid” to effective solution (Part 2 of 2)
Hamed Sanogo, Applications Engineering Manager, Maxim Integrated Products
7/21/2010 3:12 PM EDT
The term “5-NINEs availability” is often used, which corresponds to 99.999% availability (5-NINE is the percentage of time the system is operational--this translates to almost zero down time). This level of availability can only be achieved when the cards are serviced by hot-swapping them in and out without powering down the entire system. One must then be able to repair, upgrade, configure, and sometimes even expand the system on the fly without disturbing the rest of the system.
This article discusses some of the “band aid” solutions that some board-level design engineers currently use and continue to use as their hot-swapping circuits. This is followed by a discussion of a few new-generation innovative hot-swapping solutions. We first do a brief presentation of what the term “hot-swapping” means in terms of voltage transients followed by a short discussion of a few solutions designers have used to protect their systems against the effects of hot-swapping. Then we will present the very recent innovations in this technology area from a few suppliers, which fix all the short-term and long-term effects of hot-swapping.
The article is presented in two parts, as pdf files (no registration required):
About the authorHamed M. Sanogo is an applications engineering manager with Maxim Integrated Products. He graduated from the University of Alabama at Birmingham (UAB), and then earned an MSEE at the University of Michigan (Dearborn) and an MBA in technology management at the University of Dallas Graduate School of Management. Before joining Maxim, Hamed was a senior staff design engineer for Motorola, working on hot-swap enabled embedded telecomm cards for cellular base-transceiver stations (BTS) in Motorola’s UMTS, CDMA, and WiMax systems.
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Rich Krajewski
7/21/2010 11:21 PM EDT
Even my home computer system uses hot-swapping in its true-hardware RAID. The benefits of being able to swap on the fly far outweigh the costs of designing that ability in, by my reckoning, when the system is critical. I would argue, if it is truly a mission-critical operation, that we need circuit and system redundancy, and not just easy replaceability. Again, even my humble system at home has twin computers connected to an outboard RAID. If anything goes wrong with one computer, the twin can take over in about three clicks of a switch. Redundancy has the added benefit of side-stepping hot swap issues. That is, when a faulty circuit is detected, it can be automatically replaced by an already-in-place live circuit, and powered down, after which it can be replaced without fear of transient problems. When I worked for Sperry, we used redundant whole computers to monitor ship navigation in a way that made recovery from failure seamless. Bottom line, I would incorporate both hot-swap and redundancy to achieve mission-critical system reliability.
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Rich Krajewski
7/21/2010 11:27 PM EDT
I forgot to say, I liked the introduction to management of transients in hot-swapping. I'm used to the passive component methods, so it was nice to get the short introduction to ICs that incorporate transient management.
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Rich Krajewski
7/21/2010 11:36 PM EDT
Plus I liked Mr. Sanogo's shirt.
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Dr DSP
8/7/2010 6:54 PM EDT
I would like to see a comparison between the Maxim/LTC parts and some of the programmable devices that support hot swap functions, like those from Lattice Semiconductor- Power Manager II for example. The programmable devices seem to be much more flexible, but a comparison from a 'traditional' analog supplier might be useful.
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