This page contains a Flash digital edition of a book.
POWER SUPPLIES – MAKE or BUY? Mouser Electronics Helps You Decide


Mouser stocks the newest products for any power level from over 450 suppliers.


Individually, the component cost of a power supply is high compared to an off-the-shelf standard power supply without considering labor. An off-the-shelf power supply may come with a five-year warranty, as well. Thus, it makes sense to design only what you cannot buy.


But sometimes you might need a power supply that is very unique and specialized. Many companies attempt their own design. Some are successful but many incur large expenses, wasting precious time-to-market because they simply do not know how to design power supply systems that are stable, reliable, manufactured in high volume, and operate over long periods of time. Mostly, they don’t know when to design it themselves and when to buy what they need. Whether you buy or make, Mouser Electronics is there to help.


When to Buy Many times, one is told to “get that $40 dollar


part out of the networking system to cut the cost.” After all, it’s just a power supply and any fresh young engineer can do that. No? “Often, organizations with core competencies other than power electronics do not have the proper background, people, or test equipment and are unaware of associated issues,” says Mark Burr-Lonnon, Mouser Electronics’ Vice President of EMEA Business. “They dive head first into an area they are ill-prepared to navigate. The mistake is assuming that power supplies can be designed by anyone.” Why are companies outsourcing manufacturing to EMSI providers? Simply put, it costs them less and they can do a better job than in-house assembly. Consider also that your customers may have more demanding customers than you. The quality, reliability and cost have been beaten out of the process with a bigger stick than just your organization does by itself. Don’t assume that in-house design and production of power supplies will save on total cost.


When to Make


Sometimes you cannot avoid it; you must make your own power supply. When does it make sense to build your own?


1. You can’t buy what meets your needs commercially.


2. The requirement for designing your own supply can be handled with off-the-shelf semiconductors or power-supply-on-chip parts that are well supported by applications engineering staff and design tools.


3. You have access to proper test equipment and have the expertise to do the job properly.


4. There is time to do it right. Assume that nothing will be well-behaved. 5. Buying is really too much cost to justify, you will build enough to make a difference, and you feel you can do the job right.


If you consider these conditions and decide to design, the good news is that there is more support than ever before. “New developments in technology available from Mouser include products for many levels of power converter powers,” Burr-Lonnon adds. “Recent technology includes digital control for power, which allows, via a GUI, the ability to design and modify margining and sequencing, and designing, configuring, and modification of the control loop.”


Although excellent resources are available, the best advice on using reference designs is that you should not put responsibility for the design on component suppliers without some self-effort. The designer and the company with the final product are ultimately responsible for it. Don’t proceed without doing four corner testing and evaluation of the design. Make sure it will work over time and temperature. Do some evaluation and/or simulation. Never rely on only on a reference design and go straight to full volume production.


Regardless of the topology or control technology used, definitely invest in training, design tools, test equipment and software to validate the design so it will exceed expectations in the intended application. There are very good resources available in many cases at no cost or minimal investment. Suppliers can provide reference designs, evaluation boards and design software – often at no charge. Also, Mouser Electronics’ website www.mouser.com is updated daily and houses an industry-first interactive catalog, data sheets, supplier-specific reference designs, application notes, technical design information, and engineering tools.


It takes time to obtain safety agency


approvals, often at great expense. If your product will ship


internationally it will require large input ranges of 85-265VAC/50-60 HZ. It will require agency approvals for worldwide acceptance; are you prepared for the expense and delays? Do you have safety experts who know the regulatory


requirements and how to test for them? Switching supplies can generate lots of noise and worse


Block diagrams help engineers zero in on the right power supply solutions for their needs.


if they are not properly designed. Regulatory agencies have no sense of humor or sympathy for poor-switching power supply design.


More Resources than Ever Before


If, after considering the issues you still decide to make your own, it is strongly recommended that you involve suppliers early and often in the definition, selection, and design process. “Mouser carries products from over 450 suppliers with resources available for any power level. We know that the earlier you seek support and assistance, the more time you will have to do things in an orderly fashion and the greater flexibility you will have with more options – this funnel gets tighter as you get to the prototype and production phase,” Burr-Lonnon adds.


Finally, with regulations, energy efficiency, and so forth becoming a system-level consideration, considering power electronics up-front is critical. Don’t choose the wrong part, topology, or circuit only to have units in stock with failures mounting. You are not alone; there are plenty of resources available to help you implement a successful in- house design under the appropriate situations. Whether you buy or make, Mouser is there to help.


www.mouser.com Design Considerations if you “Make”


There are some questions you should ask before you make your own power supply or system. First, it’s important to consider what type of power converter system you need. This dictates the level of complexity of the overall design effort, risks, and regulatory requirements. Do you have the proper test equipment? Frequency response analyzers, electronic loads, electrical safety testers and other specialized equipment are needed. Do you have these items on hand? Do you have people with the proper skills? Consider the magnetics, PCB layout, grounding, and shielding techniques needed. The autorouter will need to be turned off and manual layout skills will be needed. Safety spacing techniques in layout must meet leakage guidelines.


Is the design off-line or DC-DC; isolated or non-isolated? Is something available off-the- shelf with proven performance? Parts with integrated supplies may be available. “At lower power levels, semiconductor components have become highly integrated with many containing the inductor inside the package forming what is commonly called PSIP, or power supply in a package,” Burr-Lonnon explains.


Mark Burr-Lonnon, Mouser vice president of EMEA, addresses the issue of making your own power supply solution.


Do you have the expertise and equipment to perform electrical safety testing on the designs to worldwide safety regulations? Do you know how to design magnetics for required clearances? Consider hours of operation; is this going to be a 24x7 high reliability application? It may make sense to buy if it is high power, off-line, isolated, and demonstrated reliability is needed out-of-the-box.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44