Teardown Tuesday: Bluetooth Headphones

According to some, the headphone jack is a thing of the past and the future of audio is wireless. In this Teardown Tuesday, we are going to take a look at a pair of Bluetooth headphones!

Bluetooth headphones come in all shapes and sizes, from relatively small in-ear headphones to over-ear headphones and neckband headphones like the ones in this teardown.


The Mpow Neckphones. Image courtesy of Amazon.

In this teardown, the headphones we are taking a look at are Mpow Jaws. These were purchased from Amazon for around $30 and they feature Bluetooth 4.1, a “Shark Design”, and an internal battery that can provide up to 13 hours of use.

Opening Them Up!

Opening these headphone up was pretty easy compared to some teardowns. There were two small Phillips screws that needed to be removed and the plastic shells of the neckband could be separated.

Earbuds Opened Up!
One of the ear buds opened

The earbuds, on the other hand, were a good bit more difficult to open. They were held together with several plastic clips and cyanoacrylate glue (super glue). The white residue inside of the headphones is caused by the glue. Inside of the earbuds is a small speaker and a strong neodymium magnet that holds the earbuds to the neckband.

Circuit Boards!


The Left bluetooth pcb
The left circuit board

Inside of these headphones, there are two separate circuit boards. The left circuit board controls the battery charging and power management. Underneath this left circuit board is a single-cell lithium battery.
The right circuit board contains the Bluetooth SOC and trace antenna. Both of these circuit boards are two-layer boards that have green solder mask and white silkscreen on both sides.

PCB Right Side
The right circuit board

The two circuit boards are connected through six conductors. These are multi-stranded, enamel-coated wires that pass through the back of the neck band. These wires appear to be hand-soldered to the circuit boards.

Connecting Wires
The wires connecting the PCBs

Bluetooth SOC


Bluetooth SOC
The CSR Bluetooth SOC

The Bluetooth SOC, in a QFN package, is really the star of this teardown. In these headphones, a CSR 8635 SOC is used to do pretty much everything. This SOC features the voltage regulators, the battery charger, Bluetooth radio, audio decoder, and noise cancellation.

Bluetooth antenna
The Bluetooth trace antenna 

This SOC is intended for applications just like this. This isn’t the first teardown we’ve seen CSR SOCs in—our Bluetooth radar detector and Bluetooth speaker teardowns also showcase CSR SOCs. As a note, in August of 2015, San Diego-based semiconductor company Qualcomm completed its acquisition of CSR.

the serial flash
The flash memory

One of the few peripherals that are not built into the SOC is the flash memory. The flash memory is located on the bottom of the PCB. The flash IC used in this is a 512kBit serial flash made by Macronix, part number KH25U5121E.

Battery


Li-Ion Battery
The Li-Ion battery

There is a single-cell Li-Ion battery that is attached to one of the PCBs by double sided tape. The battery measures 30.0mm by 11.1mm and is 5.3mm thick. There is a small protection circuit board that is attached to the top of the battery cell. The battery is connected through two small-diameter wires that are hand-soldered to the circuit board.

Input/Outputs


The Microphone
The 4mm microphone

There are quite a few user IOs on these headphones. There are the small speakers like one would expect. In addition, there are two small 0603-sized status LEDs, a microphone, four tactile buttons, and a small slide switch. Also, it appears that there is a location and the supporting electronics for a pancake-style vibration motor that isn’t included with this particular version of the headphones.

The slide switch
The power slide switch

Wrapping it Up



The Jabra BT620s. Image courtesy of Amazon.

Technology is getting smaller and smaller. Original Bluetooth headphones, such as the Jabra BT620s shown above) were substantially larger than these. Recently, Apple has announced their new Air Pods that take this functionality and make it substantially smaller.
Are Bluetooth headphones the future? Some manufacturers think so!

A diagram of Apple’s Airpods from the Keynote. Image courtesy of Apple.

Thanks for taking a look at this Teardown Tuesday! Stop by next week for another teardown!

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Hi, I`m Sostenes, Electrical Technician and PLC`S Programmer.
Everyday I`m exploring the world of Electrical to find better solution for Automation. I believe everyday can become a Electrician with the right learning materials.
My goal with BLOG is to help you learn Electrical.
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