Introduction Small Form Factor (SFF) optical transceiver packages for use at 1-2 Gbits/s data rates have been described by several authors [1-5]. These rely on dual miniature optical connectors such as the MT-RJ or the LC to provide optical-component case widths as small as one centimeter. Passive alignment of the optical fibers with the active optical devices is achieved with … [Read more...]
Keep Cool by Sensing Current to Control Fans
Control of cooling fans has become increasingly popular as efforts are made to reduce system power consumption and mechanical fan noise. The purpose of including a fan is to reduce temperature and keep it as low as possible. Mean time to failure for a variety of systems increases rapidly as temperature elevates. This has brought about a wide choice of thermally based fan … [Read more...]
Communication Network Power Efficiency Assessment, Limitations and Directions
Introduction Despite the slowdown in the communication industry, Internet traffic continues to grow rapidly, fueled by the explosion in data communications, mobile Internet, e-commerce, content rich applications, and multi-media services. Internet traffic has increased by approximately 80% yearly in each of the last three years, and will continue to grow at 60 - 80% annually … [Read more...]
Surface Flatness
Surface flatness is an important issue for thermal designers as it is directly related to thermal contact resistance between surfaces. In this column, the definitions of surface flatness related parameters are discussed. These definitions are presented here as in the ASME B46.1-1995 standard [1]. Surfaces are characterized by three main parameters: roughness, waviness, and … [Read more...]
Simple Formulas for Estimating Thermal Spreading Resistance
A problem commonly encountered in the thermal analysis of electronic packages is that of thermal spreading resistance. Thermal spreading resistance occurs as heat flows by conduction between a source and a sink with different cross-sectional areas. Examples of two situations involving spreading heat flow are shown in Figure 1. One example is that of a chip mounted on the bottom … [Read more...]
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