Switching power supply question

That's hilarious!

"James E. Salomon" should be "James E. Solomon".

I ought to know, since I was the young buck engineer, fresh out of college, working for Solomon... I'm the one who actually did all the math ;-)

Likewise on any of his noise analysis papers.

...Jim Thompson

I remember agonizing over a BOM item on a defense industry design, I thought it was outrageously expensive and pondered how to roll a discrete design. The engineering manager came along and asked why I had my head buried between my hands. When I told him he burst into laughter.

Being a taxpayer I could not laugh though.

Those must be Bay Area placement costs. But even from Europe I have heard numbers of 3-4 Euro-Cents from several people. My whole design philosophy has to change every time a client insists on domestic production.

Then one sunny day the cap mfg "improves" a cap series, resulting in even lower ESR, phssst ... BANG!

Besides, the ESR "stable range" is usually a figure and not guaranteed data. That alone is a turn-off point for me. In medical electronics where I work a lot you can't rely on typical data.

I also had some non-datasheet-mentioned pathologies. For example on a LM29xx series chip from National many moons ago. Someone absolutely wanted to have it in there despite my advice against LDOs. Turned out it did not "like" too high a source impedance. Made it oscillate, heat up and then fry. Lengthy calls, a team at National on the other side. You could hear large sheets being handled. Suddenly a faint "oh drat" could be heard over the phone and then I knew we were in deep doodoo.

Take a look at the far right where the price is listed. The ADP3331 has a realistic quantity street price around a Dollar, way above budget for a lot of designs. Especially if you can do it without an LDO.

Thanks for the links. I don't generally use LDOs but there may come a situation where it has to be one.