Introducing the Canon EOS 650D – Rebel T4i
Canon’s latest entry into the fiercely competitive entry-level DSLR market , with resplendent orange “Rebel” packaging, has hit the streets. The camera features some interesting capabilities to appeal to consumers moving up from using their phones as a primary method of recording their lives. DPReview has (as always) provided a great review, but for those interested in BoMs we will still provide a brief synopsis of the features.
In addition to all the expected imaging features, the camera’s consumer friendly features include a flip out capacitive touch screen and phase detection autofocus.
Wait. What? Phase detection auto-focus?
In short, this auto-focus capability works at the pixel-level to enable the camera to better shoot video. It represents a significant improvement over what is available in your basic handheld device. We’ll discuss more on the sensor technology later, but it means that the purchase decision for the entry level DSLR consumer isn’t determined by megapixels alone. Nor does it require an explanation on the benefits of larger versus smaller pixels, light pipes, or other means of improving light capture. It focuses (pun intended) on easy focusing to let the buyer focus (pun intended) on what matters (and can be upgraded) – lenses and accessories.
The other key specifications:
|Canon Image Sensor Using Phase Detection
Shown at right is the Canon T4i primary camera module and the LC1270 sensor. This sensor uses a technology called phase detection to enable rapid auto-focusing. We analyzed this type of technology previously in the Nikon V1 with an Aptina sensor (shown at right for comparison purposes).
Phase detection is where there are pairs of sensors that are blocked left and right (or top and bottom) and from the differences, the camera has the information needed to bring the image into focus. Please remember that teardown articles are generally focused on preliminary analysis because that is all we have at the time of publication (our Technology Blog focuses more on hard facts about the chips). With that in mind, we can see that unlike the Aptina sensor Canon is using a somewhat irregular pixel pattern for phase detection versus Aptina that used a set of regular lines. Our full report will include key information like SEM and bevel analysis to show the implementation in more detail and at higher magnification.
Canon has a fairly detailed patent application on their approach (US 2010/0165176 A1) but a detailed analysis comparing their pixel layout with that disclosed in the patent isn’t really possible with the analysis we have in hand so far.
|Image Processor and Memory
Package-on-package (PoP) is all the rage in bringing DRAM modules and processors into one component. This has the benefit of simplifying the BoM and of reducing the distance between two devices that need to communicate at very rapid speeds.
From the picture you can see that the Canon Digic 5 is located under the Elpida chip:
The Digic 5 is not the latest and greatest from Canon but for the target market and application of this processor, it represents a good value. For comparative purposes we took a look at the more recent Digic 5+ and found this die to be about 30% smaller.
This device is designed by Texas Instruments and Canon, and process clues tell us that it is fabricated at UMC. Top metal die image and markings at right.
|Some other devices
Serial flash memory – Macronix MX25L6436EM2I-10G (shown in first image)
Power management – Analog Devices ADP5035 (shown in second image)
LCD Driver – Rohm BU97930 (shown in third image)
Audio codec – Asahi Kasei AK4950 (shown in third image)
Below is a list of other parts identified in the Canon T4i Rebel:
|Manufacturer||Part Number||Device Type|
|Analog Devices||ADP5053||Power management IC|
|Asahi Kasei||AK4950||Audio codec|
|Macronix||MX25L6436EM2I-10G||Serial flash memory|
|NXP||V3700||General purpose interface|
Reports on Devices Mentioned in this Teardown