Originally Posted by
steelbikeguy
true... but things have improved since the 80's.
I recall guys designing most switchers around the common Unitrode 3524(?) controller, and the circuit wouldn't be considered small or fast by today's standards. The mosfets have improved quite a bit, and it amazes me how nicely the manufacturers have integrated the mosfets into the controllers, resulting in very small synchronous switchers that are also rather efficient.
There's also the development of the small microcontrollers that can double as a switcher controller in bike lights.
Depending on what is considered to be "fast switching", circuits have been fast for quite a while, but have gotten much faster. What was typical for the 1980's? 50kHz to 100kHz? A lot of the new little switchers are switching at 1MHz and up.
Amazing stuff, and kept me rather busy when I was helping people fix their EMC problems at work.
Steve in Peoria
Actually in 1984 I jumped from 20 kHz to 150 kHz and released a product with that. The next year my new group was on the cutting edge of increasing switching frequencies because for space you want everything smaller, lighter and with better dynamics and control. Loop bandwidth was the name of the game. The functional benefits the other writer refers to can be had as you say with megahertz switching and at 20k to 150k to a lesser degree. I didn't design them but I was part of a team that developed them for our market. And my last power electronics product was launched in 2 2005. Did not go above 100kHz, Suitable control chips, magnetics and capacitors to suit my environment, control requirements, EMC, and corporate constraints did not allow otherwise functional chips to be feasible.