Today (April 10) is
the day that the Apple Watch becomes available for order, and of course we will
be buying some to see what’s inside. We won’t be going for the gold Edition
model, even so some of us here would like to; the Sport version should be quite
good enough.
At
the Apple event back on March 9 it was almost a case of last and least for the
Apple Watch, after listening through the ResearchKit and new MacBook launches, and
more Apple Pay demos. The Watch presentation was almost a case of déjà vu, since we got most of the
details last year in the announcement last September.
The
one new technical detail that I did
pick up on was that the use of WiFi was confirmed – there was no mention of
that last year (time 74.00 in the March 9 video). There was
also much emphasis on the ability to use Apple Pay and make calls through the
Watch, so we know that there are microphones in there, and it has NFC
(near-field communications) capability, but we knew that after the initial
launch last year.
The
WiFi news was interesting to us, since we did a pseudo-teardown back then, based on Apple’s promo video,
and we came to the conclusion that the Broadcom BCM4334 was in the Watch. But no mention of
WiFi – what gives? I guess they just forgot, and even in the new launch it was
just a passing reference.
We
identified the BCM4334 from a layout image of the board inside the Watch that
we took from a screen capture of the video, and the characteristic footprint of
a flip-chip component.
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| Screen shot of PCB from Apple Watch - source: Apple film "Introducing Apple Watch" |
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| Broadcom BCM4334 die and position on Apple Watch PCB |
According to
Broadcom, “The BCM4334 is a single-chip dual-band combo device supporting
802.11n, bluetooth 4.0+HS & FM receiver. It provides a complete wireless
connectivity system with ultra-low power consumption for mass market smartphone
devices. Using advanced design techniques and 40nm process technology to reduce
active and idle power, the BCM4334 is designed to address the needs of highly
mobile devices that require minimal power consumption and compact size while
delivering dual-band Wi-Fi connectivity.”
So
we have WiFi confirmed! In the meantime we’ve been looking at that board a
little more, and we have also confirmed that the NFC and NFC booster chips used
in the iPhone 6 and 6 Plus are also present.
Again,
we looked at the footprints on the board – nothing quite as characteristic as
the Broadcom chip, but knowing the size of the chip package and the solder ball
array density gives us a good clue. And knowing the size of the BCM4334, we can work out the sizes of the other chips on the board.
In
the iPhone 6 the NFC controller was a NXP 65V10, which contained the PN548 die,
and an AMS AS3923 NFC power booster; so it’s at least a possibility that Apple
will be using them in the Watch.
Below
is the AS3923 from the iPhone, showing the 5 x 4 solder ball grid on the bottom
of the part. Like the Broadcom chip, it is also a flip-chip-on-board (FCOB), so
the die size will be characteristic, and while a 5 x 4 grid is certainly not
unique, the combination of the two gives us reasonable confidence that a
matching footprint on the Watch board indicates the presence of an AS3923.
 |
| Top and bottom images of AMS AS3923 |
Similarly
with the NXP 65V10:
 |
| Top and bottom images of NXP 65V10 |
Here
we have a 7 x 7 array, but it and the die size coincide with a footprint on the
PCB.
Lastly,
a business contact pointed out that the motion sensing is likely done by the
same Invensense sensor that was used in the iPhones, the MP67B (probably the
MPU6700), and when we looked, again the size and solder pads match. We wrote about this after the iPhone analysis, and in its lowest power mode, it can draw less than 10 µA.
 |
| Top and bottom images of Invensense MP67B |
Putting
these three together, we see below:
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| PCB from Apple Watch showing Invensense, AMS, and NXP die positions |
Come
April 24 we will know what else is in there, as you can see that board is quite
packed. In the meantime, we’ll be looking for some more recognizable
components..
