Prototyping and Evaluation

After making drawings, completing a parts list, and preparing a board layout, you can move on to the creation of a prototype and the evaluation of its performance. The first step in the prototyping process is the verification of the basic operation. That said, it is not unusual that what operation is the correct one is not known in advance. In such a case, an evaluation board supplied by the IC manufacturer could be of value. Although the board may differ from your own design specifications in detail, it provides a template for performing comparative evaluations.

Figure 34.

For measuring efficiency as one of the evaluation items, a power meter capable of measuring AC may be used. Of course, efficiency can be assessed by combining a voltmeter, an ammeter, or a clamp-type ammeter; however, newer power meters can display the efficiency itself.

Furthermore, be sure to use an oscilloscope to observe the waveform at each point, since abnormal waveforms, noise, and spikes can be discovered only through the observation of waveforms. If the circuit, operating properly on the surface, behaves erratically, waveforms can often reveal the cause of the problem.

In the evaluation process, it is also important to check tolerance with respect to input/output voltages, load current, and temperature. A design that fails to provide for an adequate margin of safety can result in increased numbers of rejects during the mass production process, and highly variable production yields in some lots. Each component that constitutes a circuit is always subject to variability. The design must be able to achieve target specifications in a manner that glides over such variabilities.