Most cell phone manufacturers have charging standards these days, even if they can't always agree on
which version of USB to use, but as the hair-tearing message above shows, third-party renditions of Apple's proprietary dock connector haven't always been universal solutions for iPods and iPhones. Now we know
another important reason why -- secret resistors placed on the data lines in connectors for each iDevice.
Minty Boost creator ladyada recently reverse-engineered the chargers for a variety of Apple gadgets, and discovered that iPhones in particular don't draw electricity until they detect 2.8V and 2V signals when they attempt to charge. At that voltage, the handsets suck down about one amp, leading to a rapid filling of your device's Li-ion belly, but by adding additional resistance to drop the voltage further, the iPhone can be coerced into accepting 500mA instead -- perfect for the set of AAA batteries you stashed away in that Altoids tin. Video after the break, full explanation at our source link.
posted August 4th 2010 9:50PM
Of course Apple would do something like this.
@KingOfSparta Neat stuff.
@KingOfSparta I'll put it to you like this. Remember that end scene in "There Will Be Blood" where he goes "I Drink Your Milkshake! I Drink It Up!". That guy was actually Steve Jobs.
@KingOfSparta
It turns out they are actually following an extended USB spec for devices that do not actually negotiate with the hub for additional power. This story has been well circulated in the past few days; I recommend looking at Slashdot's comments from yesterday for a more detailed breakdown.
Basically the resistor setup allows the iPhone to follow the USB spec, charge from computers (up to 500 mA draw) and charge faster from the wall (up to 1 Amp) with different resistors.
I don't like most of what Apple is doing these days, but this is an elegant solution not something nefarious.
@SilverTrumpet yarite, tell it to the judge bro.
@KingOfSparta
i don't believe you need reverse-engineered something that is public knowledge....
those cheap chinese factories are definitely not that smart!
@KingOfSparta
Soon people will stop reading Apple articles like this. They'll read the title and just think to themselves, "sounds about right" with no surprise.
@KingOfSparta Of course someone would make a comment saying of course apple would do this
You know if GM came out and said all of their cars would now only run on Exxon gas the feds would come down on them pretty hard. Why does Apple get a free pass?
@SilverTrumpet
Elegant like the iPhone4 side band? Oh yeah, I went there.
@KingOfSparta Jobs know what's good for you. /s
@SilverTrumpet
Yeah, but Topinsky wants to bone Ladyada... so engadget is reporting this. I don't know why this Sean Hollister guy is writing the article... maybe he wants to bone Topinsky?
@KingOfSparta Imagine if Microsoft did this in the late 90s. There would have been blood in the street.
@KingOfSparta
I always wondered why the charger from last year wouldn't work with the device of this year... are they really that different, like ffs. Waste of chargers, can't tell you how many I have...
Its a bit different because standards arent as official, theyre kind of an unwritten law. Apple hates sharing, for whatever reason, and they'll try their hardest to avoid doing so.
@sweet greggo part deux But anyone is free to make a charger with the required resistor layout.
@Plazmic Flame Not a waste for Apple cos you and millions of other have to keep buying new ones... sensing a pattern here?
@sweet greggo part deux
because our nation's economy is not based on phone chargers
@SilverTrumpet yah except the fact that apple REQUIRES charger and accessory makers to sign a NDA and pay a hefty licensing fee and HAS sued un-official accessory makers before in fact they are doing it as recently as this year
@sweet greggo part deux Yrah that really sounds like the same thing.....
@KingOfSparta
Gotta love reverse engineering.
@Phuk0ff That's how I read this. My face doesn't show any emotion of shock and my brain doesn't think of how crazy this is. I just accept this is Apple's way of doing things, and thank god I live in a free country with a free market where I'm not forced to buy one specific product (I live in Canada, you Americans aren't the only free ones out there :P)
@SilverTrumpet
I honestly don't know what's up with the article title either.
It's basically just a way for the charger to tell the iPhone/iPod how much energy to draw. It's by no means "restricting". It's a solution to let different type of charger to work.
@SilverTrumpet ehem, may i remind you, the motorola droid can do this. during pc charge it pulls less power, but charges slower. when using a wall, it rapid chargers.
you can even use higher rated chargers (although thats something you dont want)
i went to a convention and used a droid eris charger (high amp push than the normal droids i think 800 vs 500) and it would charge about 2x faster than the other drid i used on the normal charger (i brought 2 droids because im cool like that)
@huskie fluff
It´s a standard solution, the same resistors will enable the Droid/Milestone and other phones to fast charge as well without breaking the USB standard.
BTW This "hack" is already known for years. I found it on the net a few years ago when I was looking for a way to charge my iPod Touch.
@Phuk0ff thats what I did, just skipped to comments for some entertainment.
@KingOfSparta
This is a poorly written post. I'm far from an apple defender but if you watch the video it is clear the 'secret' resistors are there as a way for your iphone to determine how much power to draw NOT to lock it to certain chargers. True this isn't standard practice but it's not a standard charger it's a iPhone charger!
@KingOfSparta
Nothing seceret going on here, This is by design of the chip to draw the correct ammount of amperage the supply can provide.
Anybody that wants to understand this need only read the datasheet for the USB power management IC being used in the iPhone / iPod touch. LTC4066 by Linear tech.
Page 9, Specifically the pin descriptions of Pins 13 & 20
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1037,C1774,P12292,D26042
@fais
This _isn't_ about whether or not the iPhone can recognize chargers, or how it does it. It's about the fact that Apple refuses to allow this to be OPEN knowledge, and locks down on companies that use it to make cheaper chargers that Mr. Jobs doesn't get a kick-back for each one sold. That's the issue. Stop talking about non-sense and get to the meat of the issue.
@sweet greggo part deux
Because the old people in senate understand cars. They don't understand what a universal serial bus is, let alone what the spec is for one.
One more reason I'm getting an evo.
@sweet greggo part deux
Because this has very little to do with that? I despise apple anymore, but this is pretty straightforward. If you want to complain at someone for down-stepping current to enable devices to run on specific power sources, talk to Tesla.
Apple haters and fanboys engage in 3... 2... 1...
@Vizzy
Don't you mean reasonable people?
@Vizzy why would this enrage anyone? A lot of products (not just apple ones) have these restrictions. Their necessary at curtain points.
@Vizzy
Sooo, you believe that Apple should only allow its over priced accessories work with their devices?
I am a PC guy but I own an iPad so you can decide if I am hater...but this seems unreasonable to me.
@Vizzy I love apple. They make my tummy feel warm.
@Marbles No, what I mean is regardless of whatever topic is discussed, if it is referring to Apple even in the slightest, there will be dozens of people arguing about it just because it's Apple. It's kind of sad, people don't pay attention to articles, just the headlines.
@Vizzy and of course I got downranked. Just proves my point.
@Zo The title on this article is slightly misleading. If you watched the whole video you would have found out that the point of the article was to show that the iPhone draws different amounts of current based on the voltage it finds in the data lines which allows it to draw more or less power based on the source.
@Marbles Reasonable people don't bash anything apple just cause they like android os better, so no, he didn't mean reasonable people, idiot
@camerafan your tummy feels warm now but will be hot soon cause your device is overheating
@rjc34 I was about to post the same thing. I watched the whole video, scrolled down, and found people posting analogies of why Apple sucks. "Blind mob" syndrome much.
@rjc34 listen, if you keep positing reasonable responses,you are going to get banned faster than you can type "First1!". Try saying something like "RTFA" or "WTFM" if you want to get that point out there.
ctrl+w to speed up your computer
@Mr Hett
Finger+Powerbutton = happiness for everybody
@Mr Hett Alt+f4
iSheep don't really care, they will pay the price for a proprietary cable anyway.
Gotta love mini USB...
@Steve Jobs Jr -- Don't you mean Micro USB? (reference to the article's link: http://www.engadget.com/2009/02/23/the-1-94-reason-micro-usb-is-the-new-phone-charging-standard/)
Did anyone actually think it was just a coincidence that 3rd party chargers aren't compatible?
@Malkmus Ummm...I use a Griffin charger and a car cigarette lighter USB charger that both work fine for my iPhone 4. This has nothing to do with proprietary cables & everything to do with ensuring it's getting charged properly without getting damaged. 3rd party devices work fine as long as they put the right resistors in (which has never been a secret)