Apple Lightning Cable Teardown Reveals Mysterious Circuits

Apple iPhone 5 Teardown: Visual Tour

Give people a vacuum, and they're sure to fill it. That's certainly the case with the Apple Lightning cable and the mysterious circuitry contained therein. What is it? What is it for? Why is it even there? The lack of answers from Apple has techies the world over scratching their heads.

The Lightning cable and related port are brand-new from Apple. Apple announced them when it announced the iPhone 5, the first device to use the Lightning cable/port setup. Apple said it switched from its decade-old, 30-pin connector design to the new Lightning design in order to save space inside its mobile devices. The iPhone 5 is exceedingly thin, at just 7.6 mm.

As soon as the iPhone 5 shipped, techies were quick to strip the Lightning cable bare to see what makes it so special. Lo and behold, there are some circuits buried in that little cable.

[ Chinese company claims to be developing its own Lightning devices. Read Bootleg Lightning Devices Coming For iPhone 5. ]

The first thought that occurred to those who performed the cable lobotomies was that they are some sort of proprietary security chip, designed to make it impossible to duplicate the cable cheaply. Apple, you see, likes to sell its own stuff to consumers for a pretty penny rather than letting cut-rate competitors undercut it with lower-cost stuff.

The Lightning cable sells for $19 from Apple.com. There's also the $29/$39 Lightning-to-30-pin adapter. Right now, the Lightning cable is not available from any other company. Similar cables for other phones using the industry standard microUSB port cost less than $5, and even less when purchased in bulk. Huzzah for premium cables from Apple! Or not.

A website called Chipworks decided to take a closer look at the Lightning cable to see if it could get to the bottom of the mystery surrounding the chips buried inside it. It found four chips inside the Lightning cable die. Two of the chips are simple, each with just a single transistor.

The other two chips are a bit more interesting. The first is an NXP NX20P3. According to Chipworks, the NXP NX20P3 includes "one huge transistor occupying over 75% of the die area. It also has a fair amount of analog circuitry, as would be consistent with [NXP's] line of charging devices for peripherals."

The other chip comes from Texas Instruments, and is part number BQ2025. Though TI doesn't offer detailed information about this part, it comes from a family of chips that have shared features.

The other chips that make up the same family as the BQ2025 are listed as battery gauges. They are slightly different, but they all use a single wire SDQ interface, which is a proprietary TI tech. The BQ family of chips all also include some basic security, such as CRC generation.

Chipworks further studied the BQ2025 and found that it has its own logic block, capacitors, large transistors, and a bunch of analog circuits. Chipworks believes these are all normal components in such a cable, but the site also says that some security elements are in place.

"It is actually very interesting that we may have found a chip with (likely) some modest security in this cable," concluded Chipworks. "In this case not only related to securing their revenue stream for cables or ensuring reliable and high quality (licensed) peripherals, but in delivering useful product features that are not necessarily in the consumers' top of mind."

In other words, Apple could have added some element of security to the Lightning cable that will make it harder to replicate.

Apple hasn't responded to Chipworks' assessment, nor has it offered any explanation of what the chips buried in the Lightning cable do.

Download the debut issue of InformationWeek's Must Reads, a compendium of our best recent coverage on enterprise mobility in our new easy-to-read and -navigate Web format. Included in this issue of Must Reads: 6 keys to a flexible mobile device management strategy; why you need an enterprise app store; and Google points to the future of mobile. (Free registration required.)