Apple's iPad - The AnandTech Review
by Anand Lal Shimpi, Brian Klug & Vivek Gowri on April 7, 2010 9:39 PM EST- Posted in
- Smartphones
- Mac
- Apple
- iPad
- Mobile
USB Charging
There's been a lot of discussion about the iPad's ability (or lack thereof) to charge from most USB power sources. Even among accessories, the compatibility situation ranges from relatively to completely uncertain.
Let's start from the beginning though - it isn't like you're going to be unable to charge the thing. The iPad ships with a beefy 10.71 watt (5.1 volt, 2.1 amp) USB power supply and a heartier-than-normal feeling USB dock cable. Given the device's relatively long battery life (as we've already demonstrated), it isn't like charging is going to be something you'll do more than once a day. But Apple has left the charging situation uncharacteristically vague.
We tested charging with a number of dock connector charger accessories we had, and found the state of things confusing. Let's start with the good; Apple's ultracompact USB power adapter, the one shipped with the iPhone 3G and 3GS, does charge the iPad. If you've still got any laying around, the older, larger iPod chargers that have USB charging circuitry also work. Interestingly, both of these power adapters are only rated at 5 watts.
Support for charging from accessories from 3rd parties, however, varies wildly: devices that support firewire-only charging definitely won't work - the iPad lacks that circuitry the same as iPhones and iPod Touches. Other adapters that lack Apple-specific charging circuitry also don't work. Third party battery packs also won't charge the iPad.
Car chargers are a mixed bag - Griffin's PowerJolt SE car charger, sold at the Apple Store, doesn't charge the iPad at all. However, Belkin's Micro Auto Charger (rated at 5 watts), also sold at the Apple Store, does charge. Interestingly, the Griffin has a hard connected dock connector, while the Belkin has a USB termination and aftermarket dock cable - it's likely that the iPad favors USB-based chargers rated at or above 5 watts.
The iPad is picky about its power - it's something of a connoisseur
On the desktop side, charging is even more of a mixed bag. If you've got a PC, you're probably out of luck unless motherboard supports the USB charging specification. Remember that USB 2.0 by default supports 500 mA of current at 5 volts for a maximum of 2.5 watts. From what we've seen so far, at least 5 watts is required for the iPad to charge. Newer USB ports that support the battery charging specification can supply up to 1.5 amps at 5 volts, for a maximum of 7.5 watts. From what we've seen, it's likely that 5 watts is the requirement for USB charging to work properly. Apple's iPad charging knowledge base document mentions that a "high-power USB port" is required for charging, but neglects to enumerate what computers support the standard, or what standard they're calling high-power. Apple notes that "many recent Mac computers" support the high-power USB port charging standard, and that "most PCs or older Mac computers" will charge the iPad when it's in sleep mode.
We tested with a MacBook Pro 2,1 (pre-unibody Core 2 Duo), Mac Pro 4,1 (Nehalem), Latitude XT, and desktop with an EVGA X58 SLI - none of them charged the iPad over USB while powered on or in standby. It's a step backwards that the iPad discharges while syncing, and keep discharging if you leave it plugged into a non-supported USB port. Remember to plug it back into its special beefy power supply, or you'll likely be left without a working iPad.
The iPad a Super Head Unit is Not
Unfortunately, it looks like the dock connector circuitry on the iPad does not support car head units. We tested with a JVC KD-PDR40 and an Alpine iDA-X001 (which Alpine touts was designed in part with Apple to emulate the iPod interface), and both resulted in the following notification on the iPad:
Bad news for people with aftermarket head units
The Alpine iDA-X001 showed the following:
While the JVC KD-PDR40 constantly reported "reading" as its status:
It seems that, for whatever reason, the iPod playback hardware and software playback paths are not present on the iPad. This is disappointing, especially considering the number of car enthusiasts hoping to use the iPad as a super-sized head unit. In fact, much of the initial speculation was that vehicle integration would be part of the iPad's secret sauce. Based on these results, that obviously was never the intention.
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TGressus - Thursday, April 8, 2010 - link
"I don't think anything anyone can write can convince you"That's a tough sell right there :( Nothing against your post.
This is the challenge all tablets have faced so far. That said, if anyone has the ability to succeed in this form factor it's the iCult.
Mike1111 - Thursday, April 8, 2010 - link
"While I realize that Atom hasn't been suited for such an application until now, there's no reason Apple should've picked the A4 over Moorestown. "I really think it was the right decision for Apple to go with ARM for the iPad, and that it's the right decision to stick with ARM for at least the next few years.
(1) Mobile version of Moorestown is not available yet, the netbook one draws too much power
(2) Apple has to use ARM in it's iPhone and iPod touch for the next few years, so for cross-device OS, app and SoC compatibility and development ARM was the right choice for the iPad (e.g. if Apple makes safari use the hardware better on the iPad, the iPhone and iPod touch will directly profit from it too)
(3) Moorestown would have been more expensive
(4) With ARM Apple can control and modify the CPU design as needed, they have total control. And Apple likes that.
(5a) There is a clear upgrade path for ARM with the Cortex-A9 and a multi-core version of it.
(5b) The A4 is already fast enough for most people and most iPad tasks (how many reviews mention that the iPad is unpleasantly slow, even for the average consumer?)
It's a real possibility that an iPad with a more optimized OS and safari, a better utilized (and more programmable) GPU (like the SGX545 with OpenCL etc.) and a dual-core Cortex-A9 @1.x GHz will improve the browsing performance beyond that of a netbook. And IF APPLE SAW THE NEED FOR IT (but I don't think they do), it could happen as early as next year (other ARM SoCs like Tegra2, OMAP4 and the dual-core Snapdragon will be available by then with comparable specs, so Apple should be able to pull it off too). Intel's Atom will still be a more power consuming, more expensive and way bigger multi-chip system early next year. And beyond that are ARM quad-core CPUs and dual-core GPUs...
It will take Atom at least 4 years to overtake ARM, in the areas that count for dedicated smartphones/slates/tablets, if at all. At some point, real life browsing will just be fast enough on an ARM slate and Intel netbook, so that 99% don't care about browsing speed as a feature anymore (like it will happen with video thanks to all these powerful but small dedicated decoders/encoders like IMG's VXD/VXE).
softdrinkviking - Thursday, April 8, 2010 - link
are you saying that there is no clear upgrade path for intel's moorstown line?and that apple has complete control over the future of ARM?
i didn't know they had already gone that far.
i seem to remember apple fumbling out of the power series of CPUs and crawling into into intel's arms when they realized it was the way to go.
there is nothing to prevent apple from switching to moorstown in a couple of generations, and they have proven that they are willing to make those kind of changes when the situation demands it.
Mike1111 - Friday, April 9, 2010 - link
"are you saying that there is no clear upgrade path for intel's moorstown line?"Of course not. I'm just saying that even if you think the ARM Cortex-A8 used in the iPad is not powerful enough, that there are clear CPU upgrades coming your way for years to come (higher frequencies, Cortex-A9, dual-core Cortex-A9, quad-core Cortex-A9). It's not like Apple is using a quad-core Cortex-A9 @ 4 GHz in 22nm right now, with no better ARM architecture on the horizon and standard lithography reaching a dead end...
"and that apple has complete control over the future of ARM? i didn't know they had already gone that far."
Sorry, what I meant was that Apple has complete control over how they implement the ARMv7 architecture in a chip (since Apple has most likely an architecture license like Qualcomm).
"there is nothing to prevent apple from switching to moorstown in a couple of generations, and they have proven that they are willing to make those kind of changes when the situation demands it."
I agree that Apple can and most likely will switch to Intel if their chips are clearly superior in all the ways that matter for a mobile product. I just think that's at least 4-5 years out for retail devices so there's no point in talking about how Apple should have used Moorestown for this year's iPad... or any iPad for that matter. I don't even think that Moorestown's successor will be ready (Medfield). Maybe Medfield's successor's successor in 22nm will be clearly superior (although parity could be reached a generation earlier). We'll see.
MadAd - Thursday, April 8, 2010 - link
Its huge. Way too big for car centre consoles. If they cut it in half, so its mid way between that and an Iphone then I would definitely want to upgrade my existing car PC.Its got all the right airs and graces to be a super satnav/speedcam/music/incar wifi unit, just need to cut the size and sell it with some kind of some kind of quick release device for power and cabling (or ill fabricate one) and its a winner.
teng029 - Thursday, April 8, 2010 - link
"Companies like Crestron and AMX supply ridiculously poor touch screen interfaces to their very expensive home automation installations."How exactly did you come to this conclusion? Have you extensively either used or program a control system touch panel?
Anand Lal Shimpi - Thursday, April 8, 2010 - link
Used, but not programmed. Those touchscreen controllers are just not in the same league in terms of UI as the iPad/iPhone honestly. I haven't used the latest incarnations but from the looks of them, they haven't changed tremendously.Take care,
Anand
athreya - Thursday, April 8, 2010 - link
1. Does writepad (phatware) or sketchbook pro (autodesk) allow one to take handwritten notes on the ipad? As in, im not looking for handwriting conversion to pages or word but can notes be taken and emailed across in the body of say a gmail or a Mail message? WHich stylus is the best for the ipad?2. How do you think iphone os 4.0 will solve the multitasking problem?
3. Between the wireless keyboard and the keyboard with dock which would you recommend and why? Will ANY BT keyboard work with the ipad?
4. Can you tell us how good it is at projecting powerpoint ppts onto a standard VGA projector? Does it support Office for Mac yet?
thanks a lot Anand. Terrific balanced review as always.
strikeback03 - Friday, April 9, 2010 - link
I doubt any stylus works with the iPad, due to the capacitive screen.dagamer34 - Friday, April 9, 2010 - link
A capacitive stylus would work.