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Old 08-29-2008, 03:09 PM   #189 (permalink)
ishiyakazuo
Test Tool Engr.
 
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Quote:
Originally Posted by jmilk View Post
There's no appreciable difference in power-consumption for flash memory based on capacity. IIRC, flash only actively powers the page currently read-from/written-to, so page count is immaterial. RAM's different, but too small to matter here. Clock speed and operating voltage are just about proportional to power-consumption, however -- even so, I don't think the maximum consumption of fully clocked AT90 (0.15W at 5V/16MHz) would matter in the grand scheme of things (the LCD uses 10x that); and an ATmega328P uses even less... theoretically, it's 0.05W at 5V/20MHz).
Like I said, you'd have to be absolutely nuts to worry about the difference in power usage of the extra flash I think as size increases, the controller is slightly more complex, which adds a VERY miniscule amount to the power usage (we're talking uW here). It was basically meant to be a joke.

The ATmega328P would use less, but then you have to use the extra Microchip part, which might even things up a bit.

I didn't look at the LCD power ratings, but do backlights use that much still? I guess 1.5W isn't that bad when hooked up to a car battery, but I'm a little surprised -- I just wrapped a project a few months back with an ARM7 @ 48MHz with USB, an FPGA and a 2x16 LCD (non-backlit) and the entire setup amounted to about 1W off of a +5v supply.
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