Originally Posted by wizard69
I think your numbers are a little off, the A5X most likely runs at about 2-4 watts all out. Each core would be somewhere between a 1/4 and a 1/2 watt, and the GPUs probably one watt or even a little more now. RAM is interesting here because I'm imagining it is pretty fast RAM so it could be another watt or more.
Was going for numbers that would meet the 10 hr on WiFi and 9 hours on LTE. Going all out obviously would draw more power. No one's really done that test, so who knows what the TDP of all the parts are. MG Siegler said it got "warm" while on LTE. That doesn't sound comforting.
There are interesting data points out there. Anandtech measured 1.3 W for an iPhone 4S on 3G web browsing, 0.7 W for running a video. This is for the whole phone. Displaymate measured the iPhone 4 display at about 0.42 W. Displaymate also measured the iPad 2 display at about 2.7 W at max brightness.
From this, you can at least discern that the A5+3G is drawing about 0.9 W while 3G browsing if all the measurements are correct. If the A5X is a 45 nm part, operating at the same voltage and frequency as the A5, it's on the order of 0.75 while running a web browser.
Going all out, like playing a heavy, multiplayer 3D game with lots of radio traffic, I wouldn't be surprised at all if it only got 5 or 6 hours and got really "warm". My 4S gets really warm running 3D games.
Back lighting has always been a major power drain, even on laptops it is a significant drain. While great strides have been made (LEDs make the iPad possible) I don't see any major break through coming for conventional LEDs. The big advance will come when Apple can start to deliver entire PC boards buopilt on 22nm tech as you Wally want to get the whole PC board running on less than two watts at full performance.
The IGZO LCD should reduce the need for backlight power on LCD screens, if it ever goes into production. But yeah, I think the trends towards bigger batteries is inevitable.