Design engineers want to use parts that work. Component engineers and purchasing agents want as few parts as possible. Put the two together, and trouble ensues.
There have been times and places where a designer could make the call on the particular component needed without too much opposition from the Component Engineering group -- usually because there was no such group. But, any corporation that includes a department of component police makes a designer's job that much more difficult. Here's why.
These people have the justifiable responsibility of making sure the corporate inventory doesn't get overwhelmed by several variations of the same part, when in reality, only one type is needed. They also want to ensure that the designer's choices will be available for the life of the product, are not over-priced, and have multiple sources. Sometimes, though, they go a bit overboard in their zeal and may not always understand the components or the reasons for a choice.
Take a simple resistor -- one company's NPI (New Product Introduction) group insisted that there were really only a handful of necessary resistor values. Its component engineer (a purely digital type) was looking at those resistors as logic pull-up or pull-down. I had to explain that you can't always make a voltage divider out of 1kΩ and 10kΩ resistors, and yes, there was a good reason for the required 1 percent tolerance. Same for capacitors: Sometimes the company standard Y5P dielectric 0.1µF logic decoupling cap is not suitable for analog circuits.
I remember an incident where a colleague had designed in an octal latch -- I think it was a 74LS373 -- and on going over the timing analysis, I realized that the 20nsec data hold time would be a problem. The component cop continued to allow usage of the LS family because it was so ubiquitous and unlikely to go obsolete, but balked when I told him I wanted to use the ALS family in this particular function because of its much shorter hold time.
He was of the opinion that ALS was a passing fad, so I then told him I was going to use the F373 instead. He wanted to know why I wanted to use the F family, I told him simply "Because you won't let me use ALS." He finally agreed that maybe the LS device was not suitable and agreed to the F version. One of my engineering colleagues actually tried to specify IC sockets on his BOM (bill of materials) to prevent the cops from squelching his design choices, figuring that once the PCB was a done deal, there wasn't much that they could do. Of course, he wasn't successful in this attempt to put one over on them.
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