Anyone know what these parts are on the iPhone 6 PCB? - Page 1
Forum section: electronics / projects

author: RobK
author_rank: Contributor
timestamp: September 30, 2014, 04:04:27 pm
content: So I was looking at the pictures of the iPhone 6 teardown on ifixit.com and I noticed some small gray passive parts on the mainboard that I'm not familiar with. Was wondering if anyone is able to identify them and suggest their purpose? The parts I'm referring to are circled in red in the cropped image attached. The original image is here:https://d3nevzfk7ii3be.cloudfront.net/igi/XsO1omVUdrK4dXJQ.hugeThe way these parts are scattered around the main processor makes me think they're used to condition the power rail. You'll notice they also have polarizing marks. Perhaps they are inductors?-Rob

author: daqq
author_rank: Super Contributor
timestamp: September 30, 2014, 04:08:01 pm
content: Inductors would be my guess as well... however they might not be used to condition the power rail rather than to make it - some processors (and multi die ICs) have an integrated DC DC converter - just add an external inductor and a few caps.As for the polarizing mark, I've no clue. It might not be a mark at all, rather some technological thingie, or just for the heck of it

author: RobK
author_rank: Contributor
timestamp: September 30, 2014, 04:11:18 pm
content: Hey that's a great point daqq. Hadn't considered that possibility. I've never come across a processor that had integrated switching regulators.

author: RobK
author_rank: Contributor
timestamp: September 30, 2014, 04:13:37 pm
content: That would be a lot of switching regulators though to require that many power inductors

author: daqq
author_rank: Super Contributor
timestamp: September 30, 2014, 04:24:23 pm
content: The CPU is not exactly a single chip, but rather a few chip dies connected together -http://en.wikipedia.org/wiki/Package_on_package.Another option is that Apple might have embedded the actual switching ICs inside the PCB. Or they are so small, you don't see them. I don't know.But it's fairly certain that the inductors (if they are such) are for switching voltage regulators.As for the quantity: You can use multiphase topologies converters - instead of having a giant single MOSFET, giant single inductor etc. you get several smaller ones and make coordinate them. Seehttp://cds.linear.com/docs/en/datasheet/3829fb.pdffor example. Take a look at your PC mainboard - you won;t find one gargantuan inductor, but rather a lot of smaller ones.

author: daqq
author_rank: Super Contributor
timestamp: September 30, 2014, 04:26:17 pm
content: Seehttp://wccftech.com/intel-haswell-incorporate-integrated-voltage-regulator-320-phases-onboard-chips/for something a little more extreme, but possibly similar

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 30, 2014, 04:39:29 pm
content: It's not uncommon for inductors to have polarity markings - not often used but if packed tightly you may care about the relative phasing of adjacent ones to minimise cross-coupling.In some cases you may also care about things like putting the less noisy/sensitive end of the winding on the outside to improve electrostatic shielding

author: sacherjj
author_rank: Frequent Contributor
timestamp: September 30, 2014, 09:07:24 pm
content: Due to the thickness limitations, it is possible they are using multiples to reach the value they need. Where a thicker single inductor would have worked.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: September 30, 2014, 09:32:33 pm
content: They are inductors, we have similar inductors in our products.David.

author: tom66
author_rank: Super Contributor
timestamp: September 30, 2014, 09:41:40 pm
content: Apple's custom Dialog Semi power management ASSP is on the other side. Those inductors are for the various rails in the phone.From a leaked iPhone 4 schematic, there are 9 rails IIRC. 0.9V, 1.0V, 1.2V, 1.8V, 2.5V, 2.8V, 3.3V, 5.6V (for the LCD) and ~9V for the backlight. There is also a separate camera flash IC by Maxim which drives the white LED.This one chip has 8 buck converters, 1 boost and something like 5 linear regulators on it.

author: marshallh
author_rank: Unknown
timestamp: October 01, 2014, 02:19:03 am
content: Multi-phase buck converter