Huawei FreeBuds 4E Teardown: 14.3mm wide sound range unit, BES bluetooth audio SoC

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Huawei FreeBuds 4E continues the classic design of the previous generation in appearance. A single earbud weighs only 4.1g, providing a “sense of air” wearing experience. In terms of functional configuration, it has a built-in 14.3mm wide-range sound unit, and the sound frequency range is up to 40kHz. It supports semi-open ANC 2.0 technology and provides an adaptive and comfortable noise cancelling effect. With HarmonyOS, it also supports dual-device connection, audio streaming and other convenient experience functions.

Previously, 52audio has dismantled HUAWEI products including: Huawei FreeBuds 4, Huawei FreeBuds 4i, Huawei FreeBuds Pro, Huawei FreeBuds 3, Huawei FreeBuds and Huawei FreeBuds 2 Pro. Let’s take a look at the teardown report of this product below.


01/ Huawei FreeBuds 4E true wireless earphones unboxing

The box of Huawei FreeBuds 4E continues the compact and simple design. The front shows the overall appearance of the product, the three product features of “semi-open ANC 2.0, airy comfortable wearing, and high-resolution sound quality”, as well as the “HUAWEI” brand LOGO.

The back of the box introduces the product features in detail: semi-open ANC 2.0, comfortable wearing with air, high-resolution sound quality, full-scene dual-device connection, sliding, double-click, long-press, multiple touch operations, and low game latency.

USB-A to USB Type-C charging cable included in the package.

The Huawei FreeBuds 4E charging case adopts a “round cake”-shaped design with a matte texture, small size and easy to carry. An indicator light is designed on the front to feedback bluetooth pairing status and remaining battery information.

The back of the charging case is designed with a mirrored brand LOGO decoration integrated with the hinge.

Set the bluetooth pairing function button on the side.

The USB Type-C charging interface is located at the bottom of the charging case.

The earphones still use the reverse symmetrical placement, protruding from the cockpit for easy removal.

The inner side of the charging case cover is silk-screened with some parameter information and certification marks of the charging case. charging case: 410mAh, model: T0008L, Huawei Terminal Co., Ltd., made in China.

Huawei FreeBuds 4E

The overall appearance of HUAWEI FreeBuds 4E true wireless noise cancelling earphones.

earphones adopts a handle-shaped semi-in-ear design, which is treated with a bright surface process and has a ceramic-like texture. The surface is provided with a special coating to prevent the glossy design from being easily stained with fingerprints.

The earphone handle adopts a cylindrical design, and the noise cancelling microphone hole and touch area are set on the back. Support sliding, double-click, long-press three control modes.

earphone feed-forward noise cancelling microphone pickup hole, internal metal dust-proof mesh protection, prevent foreign objects from entering the cavity.

Metal contacts for charging earphones on the end plug of the headphone stem.

The call microphone pickup hole adopts a unique semi-closed structure design to reduce the impact of wind noise.

The tuning hole on the top of the earphone is used to improve the low frequency performance of the earphone.

The optical in-ear detection sensor on the inside of the earphone opens a window, which is used to automatically pause the music playback function when the earphone is removed.

The sound cavity tuning hole ensures the air circulation in the sound cavity and improves the acoustic performance.

The earphone has an oval-shaped sound mouth, and is protected by a fine dust-proof mesh inside to prevent foreign objects from entering the sound cavity. There is a feed-back noise cancelling microphone inside, which is used to detect the ambient noise inside the ear canal.

After actual measurement, the overall weight of Huawei FreeBuds 4E true wireless noise cancelling earphones is about 45.7g.

The charging case weighs about 37.5g.

The weight of two earphones is about 8.2g. The semi-in-ear design with a weight of only 4.1g provides a light and comfortable wearing experience.

Wired charging test for Huawei FreeBuds 4E using a portable power tester. In trickle charging with more remaining power, the input power is about 1.39W.


02/ Huawei FreeBuds 4E charging case teardown

Through unboxing, we have a detailed understanding of the overall design of the Huawei FreeBuds 4E true wireless earphones. Enter the teardown section below to see the internal structure configuration information.

Pry off the charging case cover and take out the cockpit.

The indicator light guide column on the inner side of the charging case shell.

The side bluetooth pairing function key board is connected to the cable through metal contacts.

The side structure of the cockpit of the charging case is provided with a gray plastic frame, which is fixed by screws.

The charging case indicator is provided with a rubber cover to seal to prevent light leakage.

The other side of the frame is equipped with a battery inside, which plays a very good protective role.

The main board unit is arranged in the middle of the frame.

A metal shrapnel is arranged on the side FPC cable, which is used to connect the function button small board.

The bottom of the cockpit is equipped with a USB Type-C charging interface.

A rubber cover is provided on the interface socket for sealing and waterproofing.

The positive and negative electrodes of the metal shrapnel that charge the earphone are welded to the FPC cable.

The other two metal shrapnel solder joints.

A hall element is arranged on the side of the bottom of the cockpit, which is used to sense the magnetic field change when the charging case cover is opened/closed, and then notify the charging case MCU to control the headphones to pair or disconnect from the connected device.

Remove the screws and remove the cover.

The inner side of the cover plate is also provided with a sponge pad at the position corresponding to the connector interface to assist in fixing the connector.

The internal circuit of the charging case, the components are connected to the motherboard through the BTB connector. The main board unit is set on the right, and the position of the reserved wireless charging board is on the left.

The main board of the charging case is fixed by the positioning column, and the volume is very small.

Unclip all BTB connectors and remove the motherboard.

Remove the battery unit from the frame.

Double-sided tape is arranged in the cavity to fix the battery.

There are multiple magnets at the bottom of the cockpit to attract the charging case cover and earphones.

Lithium-ion polymer battery is used in the charging case, model: HB681636ENW, rated capacity: 410mAh/1.56Wh, nominal voltage: 3.82V, charging limit voltage: 4.4V, made in China.

The back of the battery is fixed with glue on both sides.

Tear off the outer plastic skin, the silk screen information on the inner battery is consistent with the outer label, and the battery is from ATL.

The battery is equipped with a circuit protection board, and the components on the protection board are protected by black hard glue, and no specific information can be obtained.

Circuit on the motherboard side.

Circuit on the other side of the motherboard.

Female BTB connector for connecting battery cells.

BTB female socket for connecting FPC cables.

Female BTB connector for connecting to charging circuit for earphone.

Screen-printed “24AF” TVS protection tube for input overvoltage protection.

Silkscreen 2091 IC.

Silkscreen 7R4 IC.

Silkscreen 92LG voltage regulator IC.

LPS LP5280 is a general-purpose 12-ball OVP, using WCSP-12 small size package, with built-in anti-surge function, supporting IEC61000-4-5 Surge >100V, and providing over-temperature protection. The output current capability is 4.8A, the input withstand voltage is up to 29V, and the low Ron=25mΩ; with enable pin and Fault signal alarm.

According to 52audio, audio products of Xiaomi, Honor, OPPO, Huawei, Redmi, realme, Lenovo, Sony, Nokia, Motorola, Edifier, Soundcore, 1MORE, QCY, UGreen, Razer and other brands have adopted LPS. Power management chip.

Silkscreen 4502 low-voltage MOS tube.

Silkscreen XCSAIU IC.

The Cellwise CW2218 single-cell lithium battery fuel gauge chip supports system-side and battery-side applications. It has a built-in high-precision ADC for voltage, current and temperature measurement. It can accurately calculate the remaining battery power, record the number of battery cycles, and track battery aging.

According to 52audio, the audio products of Xiaomi, OnePlus, OPPO, Honor, Libratone, DJI and other brands have adopted Cellwise chips.

Silkscreen P14 MOS tube.

ST STM32F411CE High-performance basic series ARM Cortex-M4 MCU with DSP and FPU with 512 KB Flash, 100 MHz CPU and ART accelerator.

Screen printing 75NZ IC.

SGM ‎SGM41511 I2C controlled 3A single cell battery charger with high input voltage capability and narrow voltage direct current (NVDC) power path management with integrated converter and power switch for single cell Li-Ion or Li-polymer batteries. Supports fast charging and supports a wide input voltage range for smartphones, tablets and portable systems. I2C programming makes it a very flexible power supply and charger design solution.


03/ Huawei FreeBuds 4E earphones teardown

Go to the earphones teardown section. Pry open the cavity along the parting line.

The internal layout of the cavity is compact, and cables are connected between the front and rear cavities.

There is an inverted tube on the rear cavity to improve the low frequency quantity of the earphone.

Inverter tube structure front.

The back of the inverted tube structure.

The inverter tube is made by bonding the plastic cover to the shell.

The air inlet hole on the side of the inverted tube structure corresponds to the tuning hole on the top of the earphone shell, and there is a dust net inside.

The earphone’s main board is set at the bottom of the rear cavity, which is fixed and sealed by a large amount of glue, and the bluetooth main control chip leaks out to improve the heat dissipation performance.

The inside of the earphone tuning hole is connected to the air duct.

Lift up the main board, the bottom structure of the rear cavity, the noise cancelling microphone is set on the FPC board.

The acoustic structure of the noise cancelling microphone is set under the FPC board to improve the radio performance.

Noise cancelling microphone acoustic plastic cover front.

Noise cancelling microphone on the back of the acoustic plastic cover.

The inner structure of the noise cancelling microphone hole on the shell is provided with sponge pad protection and fine metal dust-proof net protection.

A bluetooth antenna is also attached to the cavity wall of the rear cavity, which is used for the transmission of wireless signals, and is connected to the FPC board through metal contacts.

Pry open the end plug at the bottom of the headphone handle, and there are cables to connect.

The inner side of the tail plug is fixed with a call pickup microphone and a metal contact for charging the earphone.

The inside of the earphone stem is coated with a lot of glue for fixing and sealing.

Peel off the glue, and connect the positive and negative solder joints of the cable to the battery.

Solder the lower cable, and the battery board circuit below.

Pull the battery out of the earphone stem.

The earphone uses a long soft pack battery that fits the cavity, and the silk screen model “HB05260ECW”.

Tear off the outer insulating plastic skin, and screen the information on the inner cell.

Small battery board, the positive and negative electrodes are welded on the cable.

The two metal connectors on the end plug of the headphone stem are used to charge the built-in battery.

Remove the headphone stem end plug after removing the metal connector.

The internal circuit of the earphone is disassembled, and all components are connected in series on an FPC cable.

Remove the earphone speaker, the internal structure of the front cavity.

A back-feed noise cancelling microphone and an optical in-ear detection sensor are fixed on the cavity wall.

Take out the internal circuit of the front cavity, and open the window of the optical sensor on the casing.

The inner structure of the earphone sound mouth is provided with a plastic part to fix the microphone.

Take out the plastic parts, the internal structure of the cavity.

Front structure of plastic parts.

The back structure of the plastic part, printed with a metal coating, welded to the cable, the function is unknown.

The word “D11” is engraved on the plastic part.

The plastic part is connected to the end of the earphone cable by welding.

Earphone dynamic speaker front diaphragm.

The T-iron on the back of the dynamic speaker is silk-screened with the words “4796 198R1”.

After actual measurement, the speaker size is about 14.03mm.

The circuit on one side of the FPC cable inside the earphone.

The circuit on the other side of the FPC cable inside the earphone.

A MEMS microphone at one end of the cable is used to pick up voice calls.

Two solder points for connecting battery cells.

Silkscreen information “L-BOT HS1HSEFLVEF.C” on the cable.

The touch sensor patch on the cable is used for touch operation function.

Headphone bluetooth antenna patch.

The internal circuit of the front cavity on the FPC cable.

The metal protective net attached to the earphone inverted hole is connected to the main cable by welding.

The other side of the metal protective net.

The earphone optical in-ear detection sensor module is used to automatically pause the playback function when the earphone is removed.

Raiden M15197’s MEMS back-feed noise cancelling microphone is used for noise cancelling function to pick up the noise inside the ear canal.

The MEMS feed-forward noise cancelling microphone of the laser carving M15F84 is used for the noise cancelling function to pick up external environmental noise.

Silkscreen MU6 L2M lithium battery protection IC.

Silkscreen mH1X Hall element.

The circuit on one side of the earphone motherboard has a neat and compact layout of components.

Circuit on the other side of the motherboard.

Silkscreen FH3997 IC.

BES BES2500YP ultra-low-power bluetooth audio SoC supports dual-mode Bluetooth 5.2, adaptive ANC function, and integrates high-fidelity audio DAC and ADC. By integrating the high-performance dual-core STAR-MC1 MCU subsystem and the ultra-low-power Sensor Hub subsystem, power consumption is greatly reduced, while also having powerful application processing capabilities. And through BES patented IBRT technology to optimize TWS application, improve RF performance in TWS system.

According to 52audio, the audio products of Xiaomi, Samsung, OPPO, Honor, Soundcore, UGreen, ZTE, Nokia, JBL, 1MORE, Baidu, OnePlus and other brands have adopted the BES bluetooth audio solution.

Screen printing 3D 8H IC.

Screen printed PA1k IC.

Awinic AW32001A Lithium battery charging IC with power path management, input withstand voltage 28V. Support 2-500mA charging current, parameters can be set by I²C interface, built-in rich and perfect protection functions, support shipping mode.

Silkscreen 5V3IC IC.

Silkscreen LS IC.

All components of HUAWEI FreeBuds 4E true wireless earphones.


04/ Summary

Huawei FreeBuds 4E inherits the family-style design style in appearance. The charging case adopts a “round cake”-shaped design with a matte texture, small size and easy to carry. The earphones are treated with a glossy surface and have a texture similar to ceramics. The semi-in-ear design and the weight of only 4.1g provide a light and comfortable wearing experience.

In terms of internal structure configuration, the circuit design of the whole machine is unconventional and compact, and it is sealed and fixed by a large amount of glue, which brings certain difficulties to teardown. The charging case adopts Type-C charging interface, built-in battery capacity of 410mAh, equipped with SGMICRO ‎SGM41511 single-cell battery charger, LPS LP5280 OVP, CellWise CW2218 single-cell lithium battery fuel gauge chip and ST STM32F411CE microcontroller for the overall regulation.

The internal components of earphones are connected in series on the entire FPC cable from the front cavity to the tail plug. The main board is located in the rear cavity, and the battery is located in the earphone handle, which adopts a long strip design. A single earphone is equipped with 3 MEMS microphones for active noise cancelling and call noise cancelling functions. Optical sensors are used to achieve accurate in-ear detection.

The earphones main control chip adopts BES BES2500YP ultra-low power bluetooth audio SoC, supports dual-mode Bluetooth 5.2, and adaptive ANC function. High-fidelity audio DAC and ADC are integrated inside to provide excellent noise cancelling function and high-quality sound quality. It also uses AWINIC AW32001A lithium battery charging IC to charge the built-in battery, integrates rich and perfect protection functions, and supports shipping mode.

Source: 52audio


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