The product development cycle for power electronic devices follows a similar path as other  electronic products, with Marketing deciding the market potential and proposing a general  requirements list for the product. There are some differences in the design and development  phases, however.

 Power electronic devices are assumed to be weak links as part of a larger machine, because of  heat generated and shortened lifetime. There is a question of reliability. Power supplies are  important to any system; if a failure occurs, the whole system is down, not just part of it.  Power products usually drive external devices, and are subject to shorts, overloads, and other  abuses. Changes of spec are common, as the attached system is being designed and modifications  occur. All too often, there are so many unknowns in the attached system that the power source  design is left to last, and then done in a big hurry, which, of course, is a management error.  "Build" or "buy" question is prevalent when a schedule pinch appears.

 Design criteria for power devices require a different kind of experience background than  digital or low level analog experience. It is likely that this background does not exist in a  company. New people must be hired or the product must be designed outside or by a consultant  to meet schedule dates. Outside permanent people are hard to obtain. Many have claimed  experience, only later it is discovered that they don't. Engineers should have at least 5  years min. of direct experience, including magnetics design, to be qualified as power  products design engineers. There is too much to understand that is not taught in schools, and  learning as an apprentice under an experienced engineer is still the best way. Courses are  available in the industry, for a fee. Also, some component manufacturers give design seminars,  which are useful.

 Product development should include a worst case analysis of the circuits to find weaknesses.  Elimination of this step for new designs is taking a giant chance towards failure.

 Procedure

 The following steps include breadboarding and possible redesign after the pc board is  produced. This is because there is a big difference between a breadboard and a finished pc  board: layout, trace resistance, circuit interactions to name a few. A PWM may be quiet in a  breadboard, but could oscillate in a pc board environment. A few companies have elected to  eliminate breadboarding and substitute circuit analysis software to analyze circuit operation  and stability. Magnetic devices should be prototyped to make sure design and coil build are  accurate before releasing a manufacturing spec.

 1. Make design spec that is agreeable to end user. Refer to  How to specify Power Supply     requirements for a sample form.

 2. Determine available space, mounting provisions, I/O connectors needed.

 3. Perform design, using previously proven circuits to save time, rather than re-invent.     Over-design output currents at least two to one. Reason: users mis-calculate their     requirements and increase needed power. It usually does not go down!

 4. Order/receive parts for breadboard and 1 or more prototypes.

 5. Breadboard and test. Temperature test. Redesign where necessary if a problem shows up.

 6. Finalize drawings and parts list. Release to mechanical design.

 7. Assist mechanical design. Check drawings.

 8. Release pc board files to fab shop. Make a few boards.

 9. Assemble 1 or more boards, and test. Redesign if necessary.

10. Finalize drawings and release.