Need a quick Bluetooth connectivity port and interface for a new cell phone design? Motorola has just the ticket. How about a Windows interface for a wireless smart display? National Semiconductors can provide a complete design for a "Mira"-enabled device. Many companies are even producing MP3 players that come entirely from a reference design.
As engineers rush to get products to market, they are turning more and more to reference designs for interface and connectivity, even entire PC motherboards and MP3 players.
Reference designs differ from popular application notes, which provide engineers with a roadmap to a design but do not necessarily have the backing of any real-world testing. A reference design can include working hardware, the bill of materials, code, any required licenses, training and support, layout files, and IP Cores. In some cases, the reference design even includes card cage and enclosure designs, manuals, and testing results. Some even suggest specific contract manufacturers.
Reference designs typically provide 80% of what is needed for a final application. The design engineer only needs to add application code, FPGA IP, and any custom hardware that will make the end application unique. "Design engineers can add their own hardware if they just want to create hardware in the FPGA to build their own reference design—one that is different from their competition," says Warren Miller, VP of marketing at Avnet Design Services.
Time savings a big plus
The value of reference designs is that they offer a head start on the design, providing a tried-and-true platform that comes with support. "We provide a design that is nearly completed but requires some customization," says Umesh Bhat, senior manager of Alliance Silicon at Xilinx Inc. in San Jose, CA. "Our generic reference designs are a good starting point for engineers."
Using reference designs for a portion of a product can allow engineers to be more creative, since they don't have to reinvent standard ports, interfaces, and technology add-ons that are now expected in many products. "As standards are adopted and portions of products become more commodity-like, you'll find that engineers would rather spend their time working on the cutting edge of the design," says Andy Femrite, regional technology manager at Melville, NY-based Arrow Electronics (http://arrow.com).
One-Stop Design: Part of a reference design, this block diagram from Arrow Electronics can be used as a PMC module or standalone single board computer.
Reference designs come in many forms. The GDA Technologies (www.gdatech.com) reference design that Arrow offers its customers is based on Motorola's latest processor, the MPC8540. The design can be purchased as a board and integrated into an end product. Or it can be used as the starting point for an 8540-based design and modified to incorporate the customer's unique features. Once the decision is made to use the processor, the engineer can start developing the software. "This greatly reduces design time, since both the hardware and software efforts can take place in parallel," says Jim Caraccio, manager of Arrow Consulting Engineering Services at Arrow Electronics.
So valuable has the time savings been that some suppliers report the use of reference designs is doubling year after year. "There has been an increase in popularity of reference designs in the last two or three years," says Arrow's Femrite. "The reference design is both a benchmark and a boost to time-to-market."
Many OEMs use reference designs to add standard functionality to a product. For example, a camera maker is likely to focus his expertise on camera design, not on the device's interface ports. The connectivity interfaces in a camera don't have to come from a new design and the interface might be weaker if it did.
Geography plays a role in how reference designs are used. For many of the high-volume, consumer products produced in Asia and Europe, reference designs often make up a large portion of the design. As a product becomes more of a commodity, more of the design is purchased. "Probably the most visible reference designs are being used in Asia in the consumer market," says Avnet's Miller. He notes that some companies in Asia even use the manual from the reference design kit as the user manual for the product.
The time saved by using reference designs varies depending on the complexity of the design and location. "In Asia it saves 98 percent of the design time—they go right to production," says Miller. "In the U.S., it can save engineers up to 90 percent of the design time on products such as PC motherboards, peripherals, cell phones, and MP3 players." In complex, high-end products, reference designs typically make up a smaller portion of the overall design, with engineers doing maybe 80 percent of the design," explains Miller.
Reference designs are not free. Costs can include purchase price, license, and support. A customer must often buy a reference design or the supplier won't sell the parts. Suppliers usually offer designs at cost in order to win the parts sale. "Our customers get all the schematics, layout files, and codes," says Miller. "We want them to copy our design so they will use the parts we sell and have in stock."