However, they don't need the same heatsinking as linear supplies, so they're less expensive in that regard. If designing an optimal heatsink (which has the second order effect of determining what else around the part will heat up because of the regulator) is a lot of work, then maybe the NRE will be the same. But overall linear regulators are fewer and simpler components so the BoM cost is a lot lower.
They were, back in the day.
Around the time the Apple II came out, a (linear) power supply wasn't cheap, but robust. And machines like it were way more expensive than its PS. The complexity of a switcher would affect that cost ratio. So few manufacturers bothered to make the PS as small or efficient as it could be.
But computers became cheaper, some more power-hungry, switching PS designs advanced (and cut down weight, size & the amount of copper needed), and markets grew. And effiency became a thing (see eg. EU regulations). So the economics made switcher designs trickle down to ever smaller & smaller power supplies.
(the latter is still ongoing btw)
Apple takes the time to evaluate new components, bothers to adapt to the new components, re-optimizes other components around the new components, ships the new components.
Eventually,... eventually someone else does too.
Not always the pattern.
But the number of ways people try to punch holes in an earned reputation is remarkable. They got the reputation for doing some things right. Maybe not everything right, maybe not the things someone thought were right, or someone thought should be right, or what they would have done, or what someone thinks they claimed they did, that they actually didn't claim...
Right. Switching power supplies need to go from off to on fast. In the full on state, the resistance is near zero (millohms with modern MOSFETs), and there's little heat dissipation. In the full off state, the resistance is near infinite (megohms with modern MOSFETs), with little heat dissipation because the current is near zero. During the transition, the switching element dissipates power as a resistor. The less time spend in transition, the less heat generated and the higher the efficiency.
Today the components are so good this is easy and efficiencies have passed 90%. That wasn't true in the Apple 2 era. Power transistors had higher OFF resistances, lower ON resistances, and slower slew rates. The better power transistors cost more. A cost-effective power supply that wouldn't overheat was tough to engineer.
(I've designed and built a switching power supply. Worked fine, could handle no-load and a dead short, and didn't blither all over the RF spectrum. Probably had twice the parts cost a good designer could achieve.)
Every modern locomotive motor is powered by a switching power supply. The transistor packages are about 10x20cm. You could hold one in your hand. They're not super-expensive. They're smaller than a mechanical switch of the same rating.
MOSFETs are insanely good switches. It's amazing that's physically possible.
[1] https://publisher.hitachienergy.com/preview?DocumentID=5SYA1...
"It switched the power on and off not sixty times per second, but thousands of times; this allowed it to store the power for far less time, and thus throw off less heat."
Aargh who wrote that?!? (not Jobs himself, I hope). Electronics designers everywhere grab their vomit bag.
Anyway, good read & well researched by Ken (as always).
(2012, 246 points, 74 comments) https://news.ycombinator.com/item?id=3636047
(2013, 170 points, 63 comments) https://news.ycombinator.com/item?id=6575994
(2021, 208 points, 158 comments) https://news.ycombinator.com/item?id=28700554
Contemporary example would be a ceo who will repeat the hallucination of an LLM as fact and then some guy on the internet will spend days refuting it.
https://www.electronicdesign.com/technologies/industrial/boa...
> To start his own company, Boschert knew he’d have to leave his 50-hours-per-week job at Microwave Associates in Sunnyvale, Calif. The ultimate motivator came when he became the custodial parent of his children. Boschert Inc. was formed in 1970 as he entered the consulting field. “I was designing power supplies to make money so we could eat,” he says.
