October 3, 2016
|By: David Andeen
Director, Reference Designs, Maxim Integrated
Many IC companies now accompany most or all of their products with a vendor-supplied reference design. This makes sense for many reasons: a good reference design speeds time to market, accelerates design-in time, and minimizes the need for the product-design team to "re-invent" the wheel.
Reference designs can be more than just a tool to check out, evaluate, explore, and jump-start a design and a project. They are also a response to the reality that many of today's ICs – even supposedly simple ones – are system-level components, and using them successfully requires expertise in a range of technical disciplines. These include analog functions, digital circuitry, firmware and code, passive component selection, power-supply requirements, and board-layout considerations.
In short, it's difficult for small (or potentially any size) design teams with tight schedules to get it all done right and right away on their own, from the first pass breadboard through to the prototyping phase. Reality is that they really would instead prefer to focus their time and resources on the proprietary or value-add aspects that they bring to their final product, using the reference design as a starting point or even core design. There's nothing to be ashamed in admitting that!
While a reference design and its smaller sibling, the evaluation board, used to be just a bare-bones tool to get the IC up and running, that's no longer the case. Today's "better" reference designs come with Gerber files, Spice and other models, test data, detailed BOM (bill of materials), drivers, code, evaluation and development tools (with PC/USB, Arduino, or ARM compatibility), and more.
In fact, some reference designs are so complete that they can be used as the basis of shippable product. For example, with the MAXREFDES79# reference design, project teams can quickly develop their own IO-Link master and interface for multiple industrial sensors, rather than pull together the different components and the critical software. The four-port reference design allows up to four sensors to be tested at one time (rather than just one), and makes it easy to plug in and quickly evaluate external sensors. This design uses TEConcept’s IO-Link master stack and is both an IO-Link master reference design as well as an IO-Link sensor/actuator development and test system.
The combination of hardware, software, and physical construction shows the complexity and completeness of this class of reference design (see Block Diagram). It includes four robust female M12 connectors (the most common connector used for IO-Link) and comes with IO-Link cables to quickly connect to IO-Link compatible sensors and actuators (see Figure) plus all other ICs, such as microcontroller, DC/DC converters, and USB interface. In addition, all design files, a compliance test report, USB driver, and PC-based GUI software can be downloaded from Maxim's site.
Of course, not all reference designs are created with equal integrity and thoroughness. Engineers must use "due diligence" and check if the reference design they see promoted at the vendor's web site was actually built, or if it only exists on paper. Even if it was built, it's important to find out to what level it has been tested and evaluated. Was it a one-off breadboard that just had to undergo a basic pass/fail checkout? Or was the reference design put through a series of tests under different conditions and operating modes, to see how well it performed in the real world? While there's nothing inherently wrong with a reference design that hasn’t been fully checked out, you do need to know the level of confidence it brings when using it.
The role of reference designs certainly has changed. There was a time when admitting you used one was almost like an admission that you really didn't know the IC and the circuit. But today's design complexity and time pressures have changed that attitude, and a comprehensive reference-design package is now expected as part of the vendor's product package and support.