Reference Designs, Dev-Kits and more: Off-the-Shelf is Fine, but Nothing Beats Customization

01/19/2022 Know-How

Application notes, user guides, development kits and evaluation boards aim to help developers achieve results with even shorter times-to-market to meet requirements that are ever more stringent. To satisfy these demands, there are a few aspects that need to be considered from the outset.

The leading semiconductor manufacturers were quick to recognize that it is not just the performance and quality of their products that affect their market performance. Extensive documentation is also a competitive advantage that should not be underestimated, because this makes it easier for product developers to implement the components.

Manufacturers are providing more and more extensive tools on their websites for this purpose. They range from entire circuit diagrams with parts lists, including all necessary passive and electromechanical components, and even tools to integrate all product data for peripheral components into the developers’ simulation tools.

Semiconductor suppliers often develop these reference designs jointly with manufacturers of electromechanical and passive components. The boards that this process produces serve superbly as test environments and as a starting point for in-house development. But they are not optimized according to the same criteria as an application for serial production. The reasons for this are obvious. Production numbers for test boards are very low, so it is often not worth performing unit cost optimization, which entails longer development times and higher development costs. The layout and space requirements of the boards are also not bound by any restrictions as the boards are not designed to be used in real environments. There are also the operating conditions of the semiconductor component to consider. These can vary greatly in a variety of applications, and this can have an impact on the requirements of all a circuit’s components.

This means that the reference design can be relatively costly and still not meet the requirements of the application in terms of dimensions and weight, or in terms of other parameters such as temperature. This is why it is worth not taking the suggestions from the reference design on simple faith.

Simplifying the Time-Consuming Search for Ideal Components

The search for components that (better) meet individual requirements can be somewhat time-consuming. You need to consider in your specific circumstances how much time and effort you wish to invest in your search for alternatives.

The 80/20 rule provides a rough but helpful guideline here: 80% of the optimization potential can be realized with 20% of the effort. For optimizing cost, it is therefore usually advisable to focus on the high-value components in the circuit.

Best practice experience and external resources can help provide greater efficiency in development, for which broadline distributors are ideal. Their application engineers and product managers are intimately familiar with the entire range of components, from semiconductors to passive and electromechanical elements to displays, boards, and systems as well as storage, memory, and wireless technologies, providing non-partisan advice on any and all manufacturers.

Example: Power Supply Units

A key example here would be power supply units, as there are just a handful of circuit constructions that have become established in this area in practice. These topologies are used time and time again in similar arrangements. This allows a considerable wealth of knowledge from previously and successfully executed projects to flow into new designs.

Sure, the requirements of specific circuits can vary greatly, but the following example shows that experience gained in the field of power supplies can be very beneficial.

The flyback converter topology is well-established in galvanic isolation-based switched-mode power supply designs for industrial applications. The starting point of development in this example is usually the choice of a suitable converter for the power class in question. The associated BOM for the reference design usually contains 40 to 60 items. Some of these items are featured several times on the board. The image shows a simplified version of a typical circuit for a flyback converter AC/DC PSU. It focuses on the main cost-driver components, which need to be selected with care, especially when producing at large volumes.

The converter, pulse transformer, common-mode choke, and the two capacitors in the diagram already account for the bulk of the cost-driver components in this application. This is why attention should focus on the choice of components.

The prioritization in this example can be applied to a variety of development projects to save costs and enable more efficient complete solutions.

Simplified Representation of a Flyback Converter Switched-mode PSU


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