> >There have been complaints about lack of AA battery power, and many felt
> >abandoned by Pentax engineers. But in fact, I don't think they have a
> >choice. K10D requires much higher voltage to run.
>
> Nope. Voltage is a non-issue these days because single-chip switching
> power supplies are small, cheap and have such amazing efficiency that
> they can be used to step up voltage almost anywhere. (In fact, I
> wouldn't be surprised if they weren't already used in the ist series
> of DSLR's) Current draw and having a battery with sufficient energy
> density are the two real issues. I'd have been happy if they'd just
> built the K10D around CRV3 rechargeables with an AA option. Still, it
> looks as if the battery grip may have sufficient space for a four-AA
> battery option. Keeping my fingers crossed.
>
>
Thanks for that comment so I didn't have to make it... :)
Switching converters are simple and efficient to do anymore. Like you
said, I'd be very surprised if the existing cameras didn't already use
them... since off-the-shelf CPUs are 3.3v, etc. Linear regulators are out
of the question for that sort of thing.
That said, many of the high-power devices are probably not
regulated. Things like the AF motor don't need regulation so much...
they'll just run slightly slower/faster if the batteries are different.
Things like the flash recharge circuit and backlight driver already have
converters to get to the high voltages required. Having designed a number
of these types of circuits, I can say that one of the main troubles is
*peak* power requirements, not average. Peak requirements are what all
the devices need to be sized for.... average just the heat sinks.
The SR system probably takes a pretty sizeable peak power, as well
as requiring a lot of EMF (voltage) to manipulate the currents in the SR
coils quickly. Not a lot of average power, but lots of instantaneous
power. Also, the DDR memory touted and the fast sensor readout/refresh
take lots of peak power.
It's still somewhat unfortunate. NiMH does have a lower energy
density per *mass*, but actually fairly comparable per *volume*.
http://tinyurl.com/jjl84
My guess is that Samsung talked 'em into it to keep the
design/production costs down.
-Cory
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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