A telecom system is an ensemble of embedded microprocessor-based cards plugged into a mid- or backplane (Figure 1). These include Private Branch Exchange (PBX), cellular Base Transceiver Station (BTS), Blade Center Telco (BCT), network data communication and storage systems. They are also classified as “high availability” systems. Once these systems are up and running, they are no longer supposed to be powered down for service or repair.
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 author
Hamed M. Sanogo
- To read Part 1, click here
- To read Part 2, click here
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.