Datasheets are indispensable, but they have limitations. Some are detailed; others are skimpy. Some show you sample schematics as a guide to using a component; many dont. None of them tells you much about how a component works, because that’s not their purpose. Often they don’t mention other components that must be added. Some datasheets for DC-DC converters, for instance, say nothing at all about bypass capacitors,
even though the capacitors may be essential. A datasheet for an optocoupler says nothing about the pullup resistor required by the open-collector output.
Datasheets don’t facilitate comparison shopping.
A datasheet from one manufacturer will not compare its
products with those from another manufacturer, and may not even provide much guidance
about alternatives that are available from the same manufacturer. For example,
a datasheet for a linear voltage regulator won’t suggest that you might do
better to use a DC-DC converter in an application where high efficiency is
important.
Most of all, datasheets don’t tell you how to avoid common
mistakes. What actually happens if you connect that tantalum capacitor the
wrong way around? A datasheet gives you the customary list of absolute maximum
values, and after that, you are on your own, burning things out, encountering mysterious
electronic behavior, and discovering limitations that are so well known, the
datasheet didn’t bother to mention them. In my experience, relying on
datasheets creates a significant risk of reinventing the wheel.
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