Teardown Vodafone Smart First 7

2017-03-21 | By All About Circuits

License: See Original Project Wireless

Courtesy of All About Circuits

Remember the time when mobile phones were just phones? Or how about when text functionality was introduced? Mobile phones have really come a long way since their creation in the 80’s. Smartphones are so common now, that you can find some for under $20. In this teardown, we will look at a Vodafone Smart First 7 to see the techniques used to make something with that much functionality so inexpensively.

The Phone That Everyone Sees

The outside of a modern smartphone is a lot more simple than phones of the past, yet is also more complex. The simplicity comes in the form of just three buttons on the front (and several on the side for power and volume control) whereas the complexity comes from the touch screen. The back of the phone reveals a 2MP camera alongside a USB port for both charging and for use as a portable drive.

The front of the Smart First 7

Taking the back off the phone reveals the SIM card holder, an SD card holder for increased storage, a battery connector, and product information (some specific to the device).

The inside of the phone

Close-up of the product information

The Lithium-Ion battery used in the Vodafone Smart First 7

Metal shielding shown behind the product information label

The Main PCB

This is as far as most users of smartphones will go before sending the device to a repair shop or back to the manufacturer. However, this is a teardown, and with that in mind, it’s time to start opening this baby up! The whole phone is kept together with 6 tiny screws found along the perimeter of the phone case (thankfully, there are no screws hidden underneath sticky labels). One cool feature found on the phone (no images, however) was that the bottom right screw had a symbol glued to the top, which was a padlock. That padlock symbol is probably a tamperproof seal where if a phone is sent back damaged and that label has been removed, the warrantee is voided.

The back of the PCB. Or is it the front? Perspective is everything!

Text on the PCB displaying product information

The obvious parts on the device include an IC labelled 3138TQ (6 channel charge pump for LED driving), USB connector, screw fittings, camera module, speaker, vibrator, SD card reader, SIM card reader, and a microphone. Considering how the back of the PCB is pretty much void of all components, it can be assumed that the controllers and important high frequency ICs are located underneath the metal shielding (most likely due to EMC regulations).

The 3138TQ6 Channel White LED Driver

Pretty gold contacts and the USB connector

Cameral module and speaker module

Vibrator

Back of the PCB

Speaker for the phone

One of the many fiducials (found just above the “MZDc” text)

The Main ICs

A smartphone cannot be made from a charge pump IC and a few passive parts, a controller of some kind is needed. Since this phone is already destined to become junk, a small circular saw (attached to a rotary tool) was used to cut the many solder connections between the PCB and the metal casings. As expected, all the important ICs came to light!

The first casing removed revealing the main controller

All cases removed exposing all parts

The first major IC is the SPREADTRUM SC7731G, which is a 1.3GHz Quad core A7 processor which contains many features such as a Modem (WCDMA/GGE), GPU (Mali 400 MP2), integrated 1080P HD Video decoding, Wi-Fi, GPS, FM, and BT all done using a 28nm feature process.

The SPREADTRUM SC7731G Processor

The second IC that sits next to the main CPU is the SK Hynix H9TP32A4GDDC which (through deduction) must be the SDRAM for the module (close proximity to the main controller). If this is the SDRAM, then it would have a size of 512MB all packaged in a ball grid array.

The SDRAM for the controller

The third IC is the SPREADTRUM SC2342A, which is a 4 in 1 RF module designed for mobile applications. A datasheet cannot be found but several websites show stock listings for the IC with a brief description. Considering the nature of the mobile device, it is safe to assume that this IC really does deal with RF communication.

The SC2342A RF Module

The fourth IC has the identification of SC2662H and is produced by SPREADTRUM. However, no information can be found on what the exact functionality of that IC is, but with a bit of thought we can speculate. Some power management ICs on the market tend to have their rating on the ident. For example, a package designed to regulate up to 1A may have “1A” in its name. This IC has .1A on the end of the second line, which may suggest that it too can handle 1A, and thus implies that it is a power management IC. Secondly, the IC is placed very close to the USB charging port which increases the chance of this IC being some form of power management for the Lithium-Ion battery. This IC may also handle the USB for the main controller considering the number of IO pins on the IC (approximately 32 pins).

The proposed power management IC

The next few integrated circuits are harder to determine and have no datasheets online. It is most likely that all of these ICs where bundled from the same distributor with some of the ICs having either custom part numbers to prevent reverse engineering or those ICs are custom silicon devices.

The SPRD SCR3232 and SC2671H

Summary

This smart phone shows how silicon devices are removing the need for many different ICs and condensing as much functionality into one device. Sure, there are multiple ICs on this PCB, but if this same device were made 10 years ago, there would easily be 10 times more ICs much larger than the ones in this phone. The use of surface mount parts has rapidly become the dominant form of production in the electronics industry with the most common PCBs now having more than 2 layers of copper. All in all, this was a high quality PCB demonstrating proper EMC control and low cost manufacturing techniques.

You can get a closer look at this design in Scheme-It