Harris drives J1850 multiplex ICs

Electronic News, Dec 8, 1997 by Gale Morrison

DETROIT--Harris Semiconductor and Chrysler are pushing forward with the "J1850 multiplexing" automobile electronics standard, and Harris said last week it is shipping production quantities of components to implement the standard. Consumers can expect to see them in the 1998 model year Chrysler cars.

1998 American cars will begin featuring what Harris termed electronic "data expressways" enabled by J1850 multiplexing engineering. These devices may save automakers hundreds of millions of dollars annually by making cars easier to design and build, it was said.

Jack Yellin, marketing manager for Harris Semiconductor's Intelligent Power Products, predicted last week that within a few years the auto industry may be purchasing 100 million or more J1850 circuit chips annually as multiplexing becomes the norm in all kinds of motor vehicles.

Fred Miesterfeld, supervisor of advanced electronic development at Chrysler, chairs the Society of Automotive Engineers' special committee that defined a national standard for J1850 multiplexing. Electronics based on the standard will appear in 1998 Chrysler Concorde and Dodge Intrepid sedans and are scheduled for future Chrysler cars, Jeeps, minivans, sport-utility vehicles and trucks.

"While the entire auto industry is likely to adopt the SAE multiplexing standard," Mr.-Miesterfeld says, "a team of Chrysler and Harris Semiconductor engineers has taken the lead by making multiplexing so affordable" that it can be implemented in their lowest-priced vehicles, like the Chrysler Neon. When Harris released the chipsets for evaluation last year, pricing started at $2 for the basic multiplexers (EN, March 4, 1996).

Harris's Mr. Yellin--when the company released its first J1850 chipsets last year--said it is important that multiplexing chips meet the standard in order to be effective. "As cars become complex--as features like power seats and windows become the industry standard rather than options--cars need a lot of wires ... (multiplexing) saves hundreds of feet of electrical wiring per car and simplifies diagnostics with direct computer interfaces."

"If you look at conventional electrical networks, you'll find a jungle of wires snaking through a car's interior, contending for space and looking for trouble," Mr. Miesterfeld said last week. "Without multiplexing," he says, "we'd have to jam twice as many wires and connectors into the cars we'll be building just a few years from now. This would mean double the wiring bulk, double the weight and double the wiring chore during vehicle assembly.

"The industry simply can't afford to keep adding complexity and cost. We have to continue to find affordable solutions. One such solution is multiplexing," he said.

As all the semiconductor companies delivering to the automotive industry know, automakers have had to add scores of wires and hundreds of connectors to cars in order to control new conveniences like automatic lighting, theater-sound stereos, dual-control air conditioners, cell phones, power seats, windows and mirrors, and satellite navigation aids. Before long, car buyers are expected to ask for further convenience and safety features and they are now being developed, such as "intelligent" cruise control, collision warning systems and devices to improve vision at night and in fog.

The J1850 parts garner a premium for the semiconductor companies, perhaps due to the engineering costs saved by the auto makers. Motorola's 68HCT05V12 8-bit microcontroller started selling for $17.50 each (EN, Dec. 23, 1996). Intel's 87C196LB conforming to the SAE communications protocol began selling for $14.50 each in 1996.

The standard further engineered by Chrysler and Harris lets sensors and control devices throughout a car communicate via a single pair of wires--in effect, a "data expressway" with on-ramps and off-ramps for each location. There, two tiny multiplexing control chips take charge of directing traffic. They guide each signal-thousands of them per second-to its correct destination instantly and without conflict, it was said.

Even though they are small and inexpensive, these specially engineered chips are helping automakers incorporate new performance, safety and convenience features, and will help auto service technicians keep customers' cars operating to specifications, including U.S. Environmental Agency (EPA) and California Air Resource Board (CARB) mandates for fuel economy and emissions diagnostics.

Harris has begun delivering production quantities of J1850 multiplexing control modules to Chrysler. Mr. Miesterfeld says the cost per car is "far less than the wires and assembly work we would otherwise need."