[PLUG-TALK] oscilloscopes are fun!

Galen Seitz galens at seitzassoc.com
Fri Mar 3 22:02:17 UTC 2006


Russell Senior <seniorr at aracnet.com> wrote:

> Which leads me to my question of the day: how do DC-to-DC converters
> work?  In the context of Power over Ethernet (PoE, 802.3af) devices,
> I've been doing some reading that leads me to understand step-down
> devices often seem to use Pulse Width Modulation (PWM), which I can
> understand, but I don't grasp how that could work for boosting
> voltage, so some kind of AC transformer (or something beyond my
> elementary-level grasp of electronics) must be involved.
> 
> Any of you solder guys want to clue me in?

RS232 transceivers typically use capacitor charge pumps.
http://en.wikipedia.org/wiki/Charge_pump

Most DC-DC converters use inductors.  Check out the buck and boost
topologies here.
http://en.wikipedia.org/wiki/Switching_power_supply#Types

galen



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