Microsoft’s first true wireless bluetooth earphones Surface Earbuds was released as early as October 2019, but due to Windows 10 system-related software and function adaptation issues, it was delayed until May this year.

For software vendors at the level of Microsoft, launching related hardware products pay more attention to the combination of software services. Surface Earbuds supports touch and sliding operations. After pairing with hardware equipped with Windows 10 and Microsoft 365 office tools, you can slide to switch PPT, enable real-time commentary and subtitle translation on the screen, or use Word, Outlook and PowerPoint Use voice dictation in. This is a difficult part of other TWS earphones at the software level.

In terms of hardware configuration, Microsoft Surface Earbuds has a built-in 13.6mm large-size dynamic driver, supports immersive Omnisonic sound effects, and supports dual-mic call voice enhancement technology; the earphones uses Qualcomm chips, supports SBC and aptX encoding, and has a single battery life of 8 hours; charging case can It provides 16 hours of battery life and is charged through the Type-C interface. And the design of the earphones is special enough, let’s take a look at Microsoft’s first true wireless bluetooth earphones Surface Earbuds through detailed disassembly!

Prior to this, 52audio had teardown the Microsoft Surface ANC bluetooth earphones and Microsoft USB-C audio conversion cable.

|1. Microsoft Surface Earbuds charging case teardown

After unpacking the box, you can see that the appearance of the Microsoft Surface Earbuds headset and charging box are designed with minimalist style as the highest standard. Let’s take a look at the internal structure and circuit through disassembly.

Let’s disassemble the charging case first, because it is ultrasonic welding, you can only pry off the bottom cover.

Charging case The physical structure of the bottom pairing button.

The internal structure of the charging case has high space utilization and numerous components.

Pick up the cable at the bottom of the charging case. There is a Hall element on the left and right earphone positions to detect whether the earphone is put in the charging case. There is cushioning foam on the back to contact the cover.

The FPC is also connected to the internal circuit, first remove the fixing screws on the motherboard and then disassemble.

Remove the screws, take out the battery and the motherboard, there are two thimble for charging the earphones soldered on the motherboard.

Pogo Pin, the other one is soldered separately on the small board and fixed.

Take out the FPC pasted on the inside of the housing. There are a number of fixed magnets underneath that are used to absorb the earphones and the box cover.

Take out the FPC inside the charging case.

The light guide of the indicator light in the charging case is surrounded by white sealing glue.

The Hall element of AFU 98 is silk-screened.

Multi-color LED indicator light under the light guide.

On the other side of the FPC, there is a Hall element on each of the left and right earphones to detect whether the earphone is put into the charging case, and the middle is the connector that connects to the motherboard.

Both sides detect the Hall element of the earphones. The charging case cover is opened/closed, and the magnetic field changes when the earphones is put in/out of the charging case will be sensed by the Hall element, and the MCU and earphones will be notified to pair or disconnect with the connected device.

The front of the motherboard structure.

The other side of the main board structure is a plastic bracket to fix the main board and the battery. The charging case uses a cylindrical lithium battery.

Another Pogo Pin for charging/transferring data to the earphones.

The plastic bracket and the motherboard are fixed together by screws, first remove the plastic bracket.

There are no components on the back of the motherboard.

The main circuit on the front of the motherboard.

Type-C tongue socket. The charging case uses the Type-C interface to input power. One advantage of the C port is that it supports positive and negative plugging, which is easy to use, and it has been very popular at present.

TI BQ24314, input overvoltage and overcurrent protection chip, supports front-end protection of lithium battery charger.

Silkscreen 8DB AL IC.

The IC of FJAR JKD silk screen is used for battery charge and discharge management in charging case.

Buck-boost chip inductors for battery charging and discharging buck-boost operations.

TI TPS62826 synchronous step-down converter, adjustable output voltage, used for charging case internal chip power supply.

TI DRV8838 driver IC is used to switch the power supply direction of earphone charging, the maximum output current is 1.8A.

TI INA212 current monitoring IC, with white sampling resistor, used to detect the charging current of the earphones.

Silkscreen 3R0 24 IC.

The IC of silk screen TC.

ST STM32F072CB, MCU with ARM Cortex-M0 architecture, with 64 KB Flash, 48 MHz CPU, USB, CAN and CEC functions.

Before the step-down current enters the battery, it also passes through a battery protection board, on which there are multiple lithium battery protection ICs and NTC thermistors to detect battery temperature, as well as secondary fuses and battery voltage detection chips for extreme conditions. Cut off the connection between the battery and the circuit.

The cylindrical lithium battery model is NTA3610, diameter 10MM, length 36MM, rated voltage 3.8V, rated capacity 300mAh/1.14Wh, charging limit voltage 4.35V.

The solder joints of the battery wires are very full.

The patch type micro button at the bottom of the charging case is used for the bluetooth pairing function of the earphones.

| 2. Microsoft Surface Earbuds teardown

Let’s disassemble the earphone part again and take a look at the design of its internal structure for uniform appearance.

The appearance of Microsoft Surface Earbuds true wireless bluetooth earphones. On the outside is a flat surface that supports touch, the earphones are in-ear design, and the silicone eartips on the outside can be replaced. Microsoft propaganda conducted a wearing test for more than 1,000 people, suitable for 95% of the human ears, and can ensure the comfort and stability of wearing.

The middle of the earphone cover is a touch area, which can realize two control modes: touch and sliding.

L/R logo is printed on silicone eartips.

Remove the silicone eartips, the size is printed on the inside, the eartip is size M.

L/R left and right logos are also printed on the inside of the earphone shell.

Close-up of pressure relief/tuning hole.

There is a metal dust-proof net at the sound hole to prevent foreign matter from entering.

The outer cover of the earphones is not seamlessly connected. There are two microphone openings inside, which are covered by a dust-proof net. One microphone points in the direction of the human mouth to pick up the human voice, and the other microphone upwards collects environmental noise.

Silver charging contacts, one on each side.

The card slot of the silicone eartip has two small metal pillars inside (the factory reserves the interface).

Strip pressure relief hole with dust net inside.

Disassemble the earphone along the parting line, and glue the upper cover.

The outer cover is a double-layer structure with L/R left and right signs on it.

Remove the plastic baffle inside the cover.

Inside the cover, the middle part is the touch sensing area, and the gold outer ring is the LDS bluetooth antenna, which is used to send and receive bluetooth signals. This part is connected with the motherboard circuit.

Earphones structure display, circular motherboard + button battery + speaker layout.

The structure in the sound cavity. The charging contacts are sandwiched between the circular magnets, and the design is symmetrical.

The charging contacts are fixed in contact with the motherboard using screws.

The speaker unit is fixed on the shell.

The speaker unit is connected with the elastic metal contact on the main board by means of contacts.

The speaker unit is fixed on the shell by red glue.

The speaker unit size is about 13.5mm.

There is a metal bracket inside the earphones to fix the button battery and the motherboard.

Button battery comes from Germany VARTA, model CP1254 A3, rated voltage 3.7V, rated capacity 0.2Wh.

According to 52audio, many world-renowned brands including Apple, Samsung, Sony, BOSE, B&O, Amazon, etc. have adopted VARTA button batteries in large numbers.

After removing the button battery, you can see the internal circuit of the motherboard.

The main circuit of the earphone, the PCBA which is a combination of hardware and software, connects the internal components.

The internal layout of the left and right earphones is opposite, and the bluetooth chip-related circuit is on the inner side and the outer side.

The plastic sheet that separates the button battery from the sound cavity. The bottom right corner is the contact that connects the positive and negative electrodes of the battery.

There are three metal contacts on the outside of the FPC to connect the speaker unit.

Columnar interface reserved by the factory.

The printed information on FPC can be divided into L/R or so.

Two laser-carved G483 9069 MEMS silicon microphones.

The memory of silkscreen 8510K R64M stores bluetooth configuration information.

Silk screen M4DE IC.

Silk screen B8F AG IC.

The IC of silk screen 620A.

The IC of silk screen TC.

Silkscreen 1R8 20 IC.

Azoteq IQS2661 touch IC, used to detect touch operations.

ST LIS2DH12TR acceleration sensor, used to detect tapping operations.

Microsoft Surface Earbuds uses Qualcomm QCC5121 bluetooth audio SoC, this chip is designed to meet consumers’ needs for a powerful, high-quality wireless bluetooth listening experience in small devices, while having low power consumption characteristics that can achieve longer audio playback.

Qualcomm QCC5121 features: very low power consumption design; bluetooth 5.0; ultra-small size; 2Mbps bluetooth low energy (LE); supports powerful quad-core processor architecture; dual-core 32-bit processor application subsystem; dual-core Qualcomm Kaliimba DSP audio sub System; embedded rom + RAM and external Q-spi flash memory; high-performance low-power audio; 192kHz 24-bit I2S and SPDIF interface; 2-ch 98dBA earphone level D; 2-channel 99dBA line input (single-ended); fully programmable Digital ANC; flexible software platform, powerful new IDE support; aptX, aptX HD and aptX Adaptive support; designed to reduce eBOM through highly integrated SoC design; support Qualcomm TrueWireless stereo and Qualcomm TrueWireless stereo enhanced version; integrated battery charger , Support internal mode (up to 200mA) and external mode (up to 1.8A).

According to 52audio, products from brands such as BOSE, SONY, 1MORE, Edifier, and vivo have all adopted Qualcomm solutions.

All components of Microsoft Surface Earbuds.

|3. Summary

Microsoft Surface Earbuds true wireless bluetooth earphones is a product with a high priority in appearance design. It seems that software companies have a soft spot for this minimalist style of hardware design. Similar products include Google’s Pixel series earphones.

First of all, let’s talk about the most unique earphone. The shell is a smooth surface. It supports two touch methods: tap and slide. Slide to cut songs, connect to Windows 10 devices to switch PPT, or enable dictation, translation and other functions. When the earphone is put into the charging case, a flat surface is formed, which reduces the height of the charging case. In order to facilitate removal, the outline of the charging cockpit is slightly larger than the earphone, but the earphone is not well positioned when it is put back.

In order to maintain a beautiful appearance, Microsoft Surface Earbuds designed the opening of the microphone at the seam on one side of the shell, which is more concealed; and the charging contacts are small, and the left and right sides are symmetrical. On the internal circuit, the earphones uses a soft and hard board to connect the bluetooth antenna and the touch circuit, the motherboard circuit, the dual microphones, the battery circuit and the speaker unit. The FPC is connected to the battery and the speaker unit through flexible metal contacts, and the charging thimble is designed to contact the main board for charging, which makes full use of the structure and space.

The bluetooth audio SoC of the earphones is Qualcomm QCC5121, supports bluetooth 5.0, supports SBC and aptX encoding, and uses LDS bluetooth antenna to transmit signals; Azoteq IQS2661 touch IC and ST LIS2DH12TR acceleration sensor are used in the earphones to detect touch operations; earphones use German VARTA button battery with a capacity of 0.2Wh and a dynamic speaker size of 13.5mm.

The charging case of Microsoft Surface Earbuds uses the Type-C interface to input power. TI’s power management IC is widely used internally: BQ24314 is responsible for input overvoltage and overcurrent protection, TPS62826 is used for charging case internal chip power supply, and INA212 is used for earphone charging current detection. The battery charge and discharge management IC model is unknown. The battery protection board has multiple complete safety protections. In order to adapt to the body structure, a cylindrical lithium battery with a capacity of 300mAh is used. The charging case MCU comes from ST to control the whole machine.

On the whole, Microsoft Surface Earbuds has a beautiful appearance and good hardware configuration, and it is undoubtedly a flagship TWS earphones product. The linkage function with the Windows system is its big selling point, and it may be a good choice for white-collar workers who rely on Microsoft 365 for office work.

Source: 52audio

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