The iPad 2,4 Review: 32nm Brings Better Battery Life
by Anand Lal Shimpi on May 4, 2012 12:50 AM ESTFinal Words
If Apple's A5 is any indication, Samsung's 32nm HK+MG process is extremely capable. Assuming Apple didn't change any fundamentals of its microarchitecture, the iPad 2,4's gains in battery life can be attributed directly to the process. The gains themselves are significant. We measured a 15% increase in our web browsing battery life, a nearly 30% increase in gaming battery life and an 18% increase in video playback battery life. Although Apple hasn't revised its battery life specs, the iPad 2,4 definitely lasts longer on a single charge than the original iPad 2.
If you're in the market for an iPad 2, the 2,4 is clearly the one to get - if you can find one that is. Unfortunately there's no sure fire way to tell that you're getting a 2,4 without opening the box and turning on the tablet, and I suspect most stores will get a bit irate if you're constantly buying and returning iPad 2s in search for a 32nm model. Presumably over time more of the available inventory will shift to 2,4 models, but based on our experiences in trying to find a 2,4 it's still pretty tough.
I would like to applaud Apple's 32nm migration plan. By starting with lower volume products and even then, only on a portion of the iPad 2s available on the market, Apple maintains a low profile and gets great experience with Samsung's 32nm HK+MG process. It's very clear that this is all in preparation for the next iPhone, which will almost certainly use Samsung's 32nm process and require it in significant volumes. It's obvious that Apple employs some very smart chip heads in Cupertino.
What I'd really like to see is a 32nm version of the A5X used in the new iPad. I don't know that there's much reason for that this year, especially when the 4th generation iPad will likely ship in the first half of 2013 with yet another new SoC (dual-core A15 + Rogue anyone?), but it'd still be nice to have. The power efficiency improvements are substantial and the 3rd gen iPad could definitely use them. Those of you who are waiting for the next iPhone should also be pretty happy about these results. Apple could easily deliver a higher clocked version of the A5 for the next iPhone while keeping power consumption equal to if not lower than where it's at today. The move to 32nm is going to be good all around it seems, and Samsung appears to be a very capable foundry partner for Apple. Despite all of the rumors of a rift in the relationship, the foundry side of things is working out well.
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dagamer34 - Friday, May 4, 2012 - link
It's kind of a shame that Samsung wasn't ready to product a 32nm A5X for the new iPad. While it's obvious that most of the battery life "issues" come from the amount of power the backlight consumes, a cooler running SoC would have been much appreciated.PeteH - Friday, May 4, 2012 - link
I doubt Apple would risk an entirely new SoC on an unproven process. If the 32nm A5 had been delayed because of process issues they could just keep manufacturing 45nm A5s and shipping iPad 2s. If a 32nm A5X is delayed, you slip the iPad 3.Samus - Friday, May 4, 2012 - link
dagamer34, the backlighting in the new iPad consumes the same amount as any other screen in any other iPad. I assume what you are trying to say is the screen is where most power consumption is used, which is correct, and the case with almost all mobile devices.The new iPad does need a die shrink, though, that's for sure. The GPU portion of the A5X consumes around 30% of the battery alone when driving full resolution graphics, which is why it has 30% less battery life than the iPad 2.
sigmatau - Friday, May 4, 2012 - link
That didn't make much sense. The iPad 3 also has a battery that's almost double the iPad 2.j2ozone - Friday, May 4, 2012 - link
The display has 4x as many pixels > which means it has 4x as much pixel wiring > which absorbs 4x as much of the backlight as older ipad display wiring > which means the backlight has to be brighter > which uses more power.mbzastava - Friday, May 4, 2012 - link
It is not the backlight that is making the huge difference in power draw. it is the quad-core gpu that is working 4 times harder than the dual-core gpu it replaced. all backlighting is done via edge-lighting, and the delta in power consumption to step up to a marginally brighter output is negligible considering the doubling of the battery capacity (doubly especial since LEDs are already pretty efficient). If you have ever taken apart laptop LCD screens you would understand.frostyfiredude - Saturday, May 5, 2012 - link
There is a more beefy backlight for the reason ozone said, go look at the review of the 3rd gen iPad and you'll see how large an effect bumping up the brightness causes compared to in previous iPads.Another way to see this is by looking at the numbers in this review where power use between the iPad 3,1 2,1 and 2,4 are compared. In H.264 playback the GPU and CPU are both doing essentially nothing so it isolates the screen fairly effectively. At the same brightness iPad 3,1 uses 4.9W, iPad 2,1 uses 2.4W and iPad 2,4 uses 2.2W. This shows that the display uses around 2.5W more power at the chosen brightness level. Looking at the same chart the GPU appears to be pulling about 2W extra (assuming moonbat works the CPU as hard as infinity blade 2).
Steelbom - Friday, May 4, 2012 - link
The iPad 3's display does actually consume a lot more power than the iPad 2's display, coming in at 7 watts per hour compared to only 2.7 watts per hour, both at max brightness.I'd say the A5 uses at most 3w when under load, and I'd give the A5X about 4w.
http://www.displaymate.com/iPad_ShootOut_1.htm
(Scroll to the bottom and then up until you find the power consumption graphics.)
victorengel - Monday, July 16, 2012 - link
Something is wrong. Your units don't make any sense. Perhaps you meant watts rather than watts per hour?lolstebbo - Friday, May 4, 2012 - link
I think you can tell if it's a 2,4 or not: presumably, only the 2,4 models would have the iCloud logo on the box.