Physical Layer Implementations of Communication Standards in Automotive Systems

Physical Layer Implementations of Communication Standards in Automotive Systems

Piet De Pauw (BVBA De Pauw, Belgium)
Copyright: © 2013 |Pages: 27
DOI: 10.4018/978-1-4666-2976-9.ch003

Abstract

This chapter is divided into three sections. The first section gives an overview of the different cables used in automotive communication systems. Although 6 different kind of cables and their corresponding connector systems have been qualified for use in automotive applications (3 electrical cable types and 3 optical cable types), up to now, only three types are commonly used: Unshielded Twisted Pairs (UTP), Coax cable, and 1 mm PMMA POF. GOF and multimode PCS up to now are not used for mass volume production. The second section overviews the optical connectors used in automotive communication systems. The electrical connectors used in LIN and CAN networks. The optical connectors standardized by MOST. In the early phase of MOST implementation, the number of MOST connectors has been large: long pigtails, short pigtails, micro pigtails, and these connectors are combined with electrical connections with a wide range of pin sizes. The number of connectors used in MOST – mainly under cost pressureis now drastically reducing. The third section overviews the different fiber optic transceivers used for MOST. The different packages for MOST25 and MOST150 transceivers are discussed. The most difficult step was the conversion of the fiber optic transceivers to be compatible with reflow SMD processes. This step is now taken. Also the evolution towards higher data rates is shown.
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Cables Used For Automotive Networks

Six different kind of cables and their corresponding connector systems have been qualified for use in automotive applications, three electrical and three optical cable types. Up to know only three types are commonly used: Unshielded Twisted Pairs (UTP), Coax cable and PMMA Polymer, Optical Fibers (POF), details are shown in Table 1.

Table 1.
Different cables (and their corresponding connector systems) qualified for automotive networks
Electrical Physical Layer (ePHY)
• Unshielded Twisted Pairs (UTP)
• Shielded Twisted Pairs (STP)
• Coax cable
Optical Physical Layer (oPHY)
• 1 mm PMMA POF
• multicore Glass Optical Fiber (GOF)
• 200 um core Plastic Cladded Silica fiber (PCS)

The main reason to limit the number of different cable types and connector systems is the high tooling and qualification costs for bringing into volume production a new cable and connector system. This poses a severe difficulty for bringing a new optical cable and the corresponding connector system into automotive volume products, especially for optical physical layers implementations.

As can be seen from Table 2, each cable solution has at least one red box, i.e. no cable system performs excellent on all required performances.

Table 2.
Comparison of different cables for automotive applications

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