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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softdrinkviking - Thursday, April 8, 2010 - link
it occurs to me that i would want a way to protect the screen from getting scratched, and that would mean acover or case that would take the place of the clamshell design of a netbook/notebook.
why would i want to pay a price premium for a device with slower performance which only achieves acceptable functionality with the addition of expensive peripherals?
even after all the peripherals, i still lose the ability to effortlessly prop-up a netbook on my lap and type an email, or set a netbook up on a table in a coffee shop.
nothing about the tablet form factor is convenient for on-the-go usage for me.
the only situation where i can possibly imagine this being a preferable form factor is for wall mount usage or some other kind of "always left out in the open" type of use, like a universal remote control, or a mini home television viewer in the kitchen.
but it seems too expensive for those uses to me.
there must be a better alternative.
MacTheSpoon - Thursday, April 8, 2010 - link
Thanks for the great review. I was shocked you'd typed 40% of it with the iPad.Would you mind doing a comparison between the iPad keyboard and a physical keyboard? Since there is no utility to measure WPM for the iPad, maybe you could time how long it takes to type the same passage on both--something with some semicolons, quotation marks, and/or em dashes would be ideal, as I'm curious how the virtual keyboard stands up when the user must switch between layouts.
Brian Klug - Thursday, April 8, 2010 - link
You know, this was something I was dying to address a few times. I'm hoping that the iTextspeed application developers update their code soon to be iPad compatible, because that's something I want to test for sure.I've gotten to the point where I can touch type in landscape pretty easy, but I can also type pretty fast on the iPhone (around 80 WPM using their application). If and when it's updated, we might do something and include the update.
If it helps any, this was also composed pretty quickly from an iPad. ;)
Cheers,
Brian Klug
solipsism - Thursday, April 8, 2010 - link
1) How did you get a 720p video on the iPhone for the video test when the allowable maximum "up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second" video?2) From my testing, the iPad uses about 20MB more than the 3GS on startup. Most, if not all, of this is for the GPU. I've also noticed that native apps are also using more RAM. While the 3GS has enough to support standard multitasking the iPad does not. Even switching pages in Safari on the iPad would have to be reloaded while the 3GS does not. This will even more of an issue with the 3G version of the iPad. This gives me doubts about multitasking unles iPhone OS v4.0 is much more efficient (making 3.2.2 a stand in, which looks to be the case) and Apple has a more intuitive quasi-multitasking concept to unveil today.
Brian Klug - Thursday, April 8, 2010 - link
I can't speak about the RAM usage - are you using iStat or similar?However 720P H.264 video is certainly supported, which is what we used. I tested all the different profiles in handbrake, all of them work if you keep the video at or under 1280x720:
"H.264 video up to 720p, 30 frames per second, Main Profile level 3.1 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats; MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats; Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format"
That's straight from http://www.apple.com/ipad/specs/
I think you're getting confused with the MPEG4 limitation which is indeed 640x480. ;)
-Brian Klug
Ph00 - Thursday, April 8, 2010 - link
sorry to be ot but is that a black mouth cur dog?Griswold - Thursday, April 8, 2010 - link
I'll wait for iPad v2 with reliably working wifi, no overheating, working PDF export, at least a backside camera for snapshots and maybe short flicks and perhaps multitasking. Ill stop here because any more missing features would seem greedy - apple needs a reason to sell you the 2012 iPad...As for atom based ipad - are you nuts? Nobody wants that garbage. Gimme a dual core cortex A9 instead.
Mike1111 - Thursday, April 8, 2010 - link
You mean the 2011 iPad, right? Because there's no way Apple isn't gonna do a yearly refresh cycle like they do with all their iPhone OS based products.Mike1111 - Thursday, April 8, 2010 - link
My mistake. You meant even iPad v2 in 2011 won't be feature complete because Apple needs some features for the 2012 iPad v3.Hm, how do I delete a post?
Lemonjellow - Thursday, April 8, 2010 - link
"Sure, but so could a TV that made me pancakes. Neither is ready yet or guaranteed."Can you confirm or deny that someone is working on said TV project? :- D