Article published in Hearst Semiconductor Applications

COAX Cabling for 1394 Vehicle Networks Offer Highest Data Speeds, Lowest Cost

By Peter Helfet, EqcoLogic NV



Copper is the medium of choice for in-vehicle networks, including entertainment and navigation systems, and offers very high data rates.

The 1394 Copper Automotive Standard, the blueprint for next generation networking in cars, will offer net data rates of up to 800Mbits/s (1394 “S800” speed), from the start. This compares extremely favorably with 25Mbit/s offered by MOST optical networks today and even the “future” 150Mbit/s MOST specification.

The 1394 Copper Automotive Standard also allows for networks built on a number of cable/connector systems, including “Shielded Twisted Quad” (STQ), “Shielded Twisted Pair” (STP) and single COAX operating in full duplex mode.

The COAX Option

To work with COAX cabling, small, low cost transceivers are required at both ends of the cable. The COAX transceiver connects to standard 1394 PHYs (physical layer controllers). Each transceiver has a cable driver to launch transmit signals onto the cable and a receiver with adaptive equalizer to receive and enhance signals. The COAX transceiver also supports node “wake-up” requirements to allow the complete system node to shut down when not needed. The COAX transceiver "sleeps" in a very low power state and wakes itself and the PHY when signals are received from another device on the network.

Using low cost automotive COAX cables, like the RG174 with FAKRA COAX connectors, the transceiver allows a cable range at S800 speeds of up to 20m with the network operating at S800 even with a number of in-line connectors. This is effectively double the range achieved with current STQ or STP cable systems. In addition, COAX cabling and connectors are very low cost so that, even taking into account the addition of the transceiver circuits, total link cost can be as low as 50% of the cost with more complex cabling. The COAX cables and connectors are low cost because they are in very high volume production, being used in many different applications and environments; in addition, their construction is simple, allowing fully automated termination and inspection.

COAX transceivers can be soldered directly to a PCB within the host electronic device or can be sourced integrated into a high quality connector. The two solutions illustrated below are developments from two added-value connector vendors planning to offer the industry a simple solution to integrating COAX support for 1394 network products.

Two approaches to active connectors are developed by Radiall of France and US company, Autosplice respectively.

In both cases, the electronics are integrated in a well shielded metal housing that is easily mounted on printed circuit boards. Radiall bonds the transceiver silicon directly to the miniature circuit board, making for a very compact package. Autosplice uses its automotive approved compliant pin technology to create a solder free final assembly for Tier 1 suppliers along with design features to couple the integrated connector to the chassis for enhanced EMI/RFI protection. With these active connectors, customers will have a number of ways of implementing an optimized 1394 COAX network. EqcoLogic provides the EQCO 800SC transceiver that is sampling now and is being evaluated by a number of automotive suppliers and OEMs. It will be available in volume in 2009. For details of their product offerings, please check out product offerings.

About the Author

Peter Helfet is the chief executive of EqcoLogic. An experienced entrepreneur, Peter led the creation of EqcoLogic, working with the team since early 2004. A graduate of Cambridge University in the UK, Peter's early background was in multi-nationals. In the 1980's, he moved into the high-tech start-up sector and was founder and CEO of a major UK technology company, Plasmon PLC, managing it through an IPO in 1996. Since then, and until starting with EqcoLogic, he has worked mainly with start-ups and VC investors in management and advisory roles.

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About EqcoLogic

EqcoLogic is a privately funded Belgian company spun-out of the Vrije Universiteit Brussel. Formed in 2005, the company is commercializing the University's innovative high speed digital SERDES Equalizer technology made available through an exclusive world-wide license.

EqcoLogic is a fab-less semiconductor vendor, developing and supplying cable Equalizer devices; the company also sub-licenses the core technology and product designs in certain markets. Along with exceptional signal recovery, EqcoLogic chips offer excellent operational tolerances and low power consumption. Designed for standard CMOS processes, the circuits can also be integrated into other communications chips. EqcoLogic is targeting video, audio, automotive and server applications with a number of business partners.