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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Tuvok86 - Friday, May 4, 2012 - link
do you think Apple will introduce the 32nm soc on iPad 3 silently or they will wait for the next iteration?guidryp - Friday, May 4, 2012 - link
"Note that idle power is actually higher than video playback simply because there's more that's being driven on the display, at a higher intensity on the iOS home screen than on a dark 16:9 video."That really doesn't make sense. This is LCD, not OLED. Displaying black/white should take about the same amount of power, because the backlight is uniform and covers the whole display. It doesn't turn off on dark areas of the screen.
Perhaps Apple cheats and turns down the brightness while a movie plays. Create a movie that has a pure white screen and measure nits...
André - Friday, May 4, 2012 - link
No need to call shenanigans. You simply failed to read what was written.It isn't the screen that uses less power but the SoC because it has dedicated hardware for video playback.
guidryp - Friday, May 4, 2012 - link
He is clearly talking about screen content, when he mentions "dark 16:9 video" which implies that power changes drastically dependent on what is displayed.This is true for OLED screens, but untrue for LCD screens.
Also while dedicated Video decode HW offloads work from CPU/GPU, they essentially have no work to offload while idle. Really great dedicated Video decode HW could get you to idle consumption, but I don't see how it could get you below idle.
Something very strange here.
PeteH - Friday, May 4, 2012 - link
What about bandwidth? 8-bit 4:2:0 video is a bit less than 40% of the size of 8-bit ARGB (for equivalent source dimensions).Anand Lal Shimpi - Friday, May 4, 2012 - link
There could be a handful of things happening here:1) It is possible to have a small reduction in LCD power consumption by displaying black vs. white. The gap isn't anywhere near as dramatic as it can be on an OLED display, but it can be measurable. This alone can't explain the difference, I agree.
2) It's possible that Apple is putting the SoC into an even lower power state when a video playback scenario is triggered. Apple does quite a bit of aggressive power management so this wouldn't be too far fetched.
3) It's not clear to me if Apple is doing any localized dimming, which would have a significant impact on video decode power consumption.
Take care,
Anand
guidryp - Friday, May 4, 2012 - link
I think the back-light as the largest power draw (especially in idle), is the easiest source of savings. Displaymate measured 7watts at max for the back-light alone on iPad 3 !Easy reductions either from a simple general brightness reduction when a movie is playing, or dynamic backlight control while a movie is playing. Done right it gets some savings while being hard to notice.
I really don't think you can get a much lower power state while playing video, than while just displaying a start screen. In either case the CPU is still running, still instantly ready for touch, or sensor reactions.
However they did it, it is a slick piece of engineering.
Pshooter - Friday, May 4, 2012 - link
http://www.displaymate.com/iPad_ShootOut_1.htmBSMonitor - Friday, May 4, 2012 - link
"This particular iPad 2,4 sample came from Best Buy, and several attempts to find one elsewhere came up short. All indications seem to point to the iPad 2,4 being relatively rare, which makes sense considering what's inside it."Was one of the other attempts Apple's own website??
Anand Lal Shimpi - Friday, May 4, 2012 - link
The other tries were at an Apple store (3x) and a Walmart (1x).Take care,
Anand