At the beginning of the new year of 2021, Huawei released this year’s new TWS true wireless earphones ——Huawei FreeBuds 4i through online live broadcast. 52audio has conducted a detailed experience review on it before. The body size of the earphones and charging case is larger than that of Huawei FreeBuds 3. Both the FreeBuds Pro and FreeBuds Pro are small and portable; the active noise reduction function can significantly reduce the low frequency noise that is often encountered in life scenes, and the noise reduction experience is more comfortable, and it also supports the ambient sound transmission mode.
In terms of call noise reduction capability, Huawei FreeBuds 4i uses a unique windproof structure at the microphone inlet position, which has a certain suppression effect on wind noise. At the same time, it also supports call noise reduction algorithms to make the call voice clear; in music mode, earphones The single battery life with noise reduction turned on is 7.5 hours, and the noise reduction mode is turned off to 10 hours. Such a long battery life is the only gear of Huawei’s true wireless earphones products.
Although the Huawei FreeBuds 4i adopts a combination of numbers and letters in the naming method, it is not a flagship series of pure numbers or letters, but the configuration and actual use experience of this product are better, and the price is more affordable. Huawei thinks It is necessary to push the whole people into the era of wireless earphones through this product. Let’s take a look at the detailed dismantling report of 52audio!
Huawei’s true wireless products previously teardown by 52audio include: Huawei FreeBuds Pro, Huawei FreeBuds 3, Huawei FreeBuds 2 and Huawei FreeBuds true wireless bluetooth earphones.
| 1. Huawei FreeBuds 4i charging case teardown
After unpacking the box, I believe that everyone has a preliminary impression of the appearance design of Huawei FreeBuds 4i wireless earphones, retaining many classic elements of the previous generation products. Next, we will enter the dismantling link to take a look at its structural design and material information.
Pry open the charging cockpit, and the internal structure is fixed by buckles and black glue.
The shell buckle and black sealant enhance the ability of dust and water resistance.
Take out the key structure, the outer shell is the same as the charging case shell, which is processed by piano baking paint process.
On the side of the button structure, there is a ring of rubber pads that play a role of dust and water resistance.
The internal structure of the back of the charging case is sealed with glue at the edge, the cover is connected to the body with a shaft, and there is a black cushioning foam in the battery position.
There is dust-proof foam at the charging port.
The light guide plate at the position of the indicator light.
The front of the charging case internal structure, the internal circuit is fixed on a plastic middle frame, and the front cover is fixed by a number of screws.
On the back of the internal structure of the charging case, the battery is fixed in the groove of the plastic middle frame.
The bottom surface of the internal structure of the charging case.
The charging case shows the structure of the button position on the side, and the black rubber pad covers the micro switch.
A close-up of the micro-motion button, which is connected to the motherboard through the FPC.
Remove the screws and remove the cover of the plastic middle frame structure.
Middle frame structure layout.
The welding position of the two FPCs is reinforced with red glue.
Remove the plastic part that is used to reinforce the charging port.
Internal structure of charging case.
The battery is fixed in the groove of the middle frame with double-sided tape.
A close-up of the inside of the charging cockpit. There are two larger magnets in the earphone sound cavity for attaching and fixing the earphones, and two bar magnets in the open position of the box cover for attaching the box cover. This FPC is connected to the side buttons, two charging Pogo Pins and Hall elements.
The Hall element of silk-screened AVOP. The magnetic field changes when the charging case lid is opened/closed and the earphones is taken out/replaced will be sensed by the Hall element, and the charging case will be notified that the MCU and the earphones are paired or disconnected with the connected device.
The metal dome at the bottom of the earphone handle is connected to the motherboard through another FPC.
There is also a charging case status indicator on this FPC, which is composed of two LED indicators. The outer ring rubber part prevents light leakage and has a certain degree of dust and water resistance.
The silicone protective cover at the charging port position improves the water resistance.
USB Type-C charging interface female socket, through-hole welding, improve the stability of plugging and unplugging.
The silicone protective cover has a test paper inside to detect whether water has entered, which is convenient for after-sales.
Soft pack battery information, model: HB472023ECW, rated capacity: 215mAh, rated voltage: 3.82V, charging limit voltage: 4.4V. Under the premise of a small body and a reinforced middle frame, it is not easy to insert a 215mAh battery. Small size and long battery life cannot be achieved at the same time.
A close-up of the battery protection board. There are lithium battery protection IC and PTC thermistor to provide battery over-voltage, over-discharge and over-current protection, and the battery protection chip is glued. The battery is connected to the motherboard through the FPC and BTB connectors.
One side of the motherboard circuit.
The other side of the motherboard circuit.
There is a TVS at the input of the charging case, Willsemi ESD56241D18, which is used for input overvoltage protection.
The regulator tube of silk-screen MGL.
Silkscreen HCCU AED IC.
ETAsolutions ETA1061 1μA ultra-low quiescent current, 1A synchronous rectification boost converter, boosts the battery output to charge the earphones. ETA1061 fully integrates the upper and lower power tubes, realizing a single-chip synchronous boost. The 5.0V output can be fixed or the voltage can be adjusted from Vin to 5.0V through an external larger resistor.
It has a built-in switching frequency driver up to 1.4MHz, so that the external inductance can be as low as 2.2μH, and the package is more compact. The volume of the conventional flat chip 3mm*3mm can meet the demand. Not only that, the extremely high frequency also omits numerous Cout output capacitors.
According to 52audio, audio products of well-known brands including Edifier, 1MORE, XIAOMI, ZMI, realme, Baidu, Motorola, JVC, Panasonic, and JBL have adopted ETAsolutions power management chips.
The IC of silk screen ED E.
The IC of the silk screen TSB.
The IC of the silk-screen CD.
Silkscreen LA’s IC.
The IC of the silk screen 3GP4 QAA8 1050 3016 comes from AWINIC, model AW32001ACSR, is a lithium battery charging IC with power path management, input withstand voltage 28V, support 2-500mA charging current, parameters can be set by I²C interface.
GigaDevice GD32F303CCT6 single-chip microcomputer. The GD32F303 series of single-chip microcomputers are 32-bit general-purpose single-chip microcomputers based on the M4 core, with high performance ratio and enhanced processing capabilities. It is used to realize charging case control functions such as charge and discharge module management, battery power management, earphones communication, online upgrades and production testing.
| 2. HUAWEI FreeBuds 4i earphones teardown
Let’s continue to disassemble the Huawei FreeBuds 4i earphones. The earphone adopts a handle-type ear design, which is designed for active noise reduction. The length of the earphone handle is smaller than that of Huawei FreeBuds 3, but it is flatter and has a larger contact area with your fingers. Large, easier to locate when touching.
On the outside of the earphone handle, the earphone supports two touch modes: tap twice and long press; there is a call microphone in the slender opening at the bottom.
The noise-canceling microphone of the earphone is located at the top position inside the earphone handle, and the design of the through-the-hole slit pipe is similar to the design of Huawei Freebuds Pro in order to improve the ability of wind noise resistance.
Charging contacts at the sound cavity location.
There is another charging contact at the bottom of the earphone handle, with the L/R logo on the top.
The product information on the shell, model T0001, and IC code and CMIIT ID.
The pressure relief/tuning hole in the back cavity of the earphone has a dust-proof net inside.
The pressure relief/tuning hole in the front cavity of the earphone has a fine dust-proof net inside.
A fine dust-proof net at the mouthpiece prevents foreign objects from entering.
Disassemble the earphone along the parting line and take a look at the structure inside the earphone handle first.
A large amount of sealant is used at the seams of the shell to improve the waterproof ability.
There is a plastic part on the top of the earphone handle to fix the touch-sensitive FPC.
The touch-sensitive FPC is fixed with glue, and the plastic part is fixed on the motherboard by a buckle.
The internal layout of the earphone handle shell.
The internal layout of the earphone handle.
Below the plastic part are two BTB connectors to connect the circuit of the front cavity.
At the bottom of the earphone handle, the metal charging contacts are welded to the main board.
Disconnect the connector and take out the motherboard.
The internal layout of the earphone handle shell, the middle position is the protective cover of the noise reduction microphone, and there is a lot of sealing glue on the edge.
The charging contacts at the bottom of the earphone handle are welded to the motherboard through the metal on the side, and a lot of glue is used for sealing.
One side of the motherboard circuit.
The other side of the motherboard circuit.
Huawei FreeBuds 4i earphones adopts the BES BES2500Z bluetooth audio SoC and supports the latest bluetooth 5.2 standard. It was previously applied on OPPO Enco X true wireless noise reduction earphones, model BES2500Y, which is a dual-core digital bluetooth noise reduction chip. The suffix is different and the configuration is different, which is customized by the manufacturer.
According to 52audio, a large number of true wireless earphones from brands such as Huawei, Samsung, Xiaomi, OPPO, JBL, 1MORE, Honor, Baidu, and OnePlus have adopted BES bluetooth audio chips.
The bluetooth signal filter of silk screen bRwV.
Onboard bluetooth antenna.
The IC of the silk screen 3GP4 QAA4 2105 2067 is consistent with the IC model of the charging case.
GOODiX GH610, supports in-ear detection and touch 2 in 1 solution. Goodix GH61x series chips, using human capacitance detection patented technology, can assist true wireless earphones to achieve automatic sleep, automatic wake-up, master-slave switching, automatic music start and stop functions, and improve user experience. At the same time, it supports touch, sliding volume adjustment, etc. Rich human-computer interaction functions. The chip integrates PMU and MCU, the algorithm runs independently on the chip, and reports events directly to the main control without the main control for data processing.
According to 52audio, many TWS earphones from brands such as JBL, OnePlus, OPPO, realme, vivo, Baidu, 1MORE, etc. have adopted GOODiX’s in-ear detection and touch 2-in-1 solution.
Laser carving Z0BB81’s MEMS silicon microphone picks up ambient sound for active noise reduction, ambient sound transmission and call noise reduction functions. The earphones uses a feedforward noise reduction scheme.
Another MEMS silicon microphone at the bottom of the earphone handle is used for call sound pickup and auxiliary noise reduction.
The Hall element on the top of the earphone and the reserved accelerometer pad.
Disassemble the shell along the parting line, continue to disassemble the front cavity part, use a lot of glue to seal the joints of the battery.
The speaker unit is connected to the small board on the battery through the FPC and the connector.
The charging contacts of the sound cavity are on a separate FPC.
Connect the connector of the speaker unit FPC.
The solder joints of the positive and negative electrodes of the button cell.
Open the solder joints and remove the button battery.
Button battery information, ICR12/07, diameter 12mm, thickness 7.0mm, model HB1160ECW.
The battery has a rated capacity of 55mAh, a rated voltage of 3.82V, and a charging limit voltage of 4.4V.
Label information on the battery case.
The battery label information on the other side.
Transparent bracket for fixing the battery.
The FPC in the front cavity is connected to the charging contacts, the ear detection FPC, and the touch detection FPC, and is connected to the motherboard through the BTB connector.
The other side of the FPC.
The magnet that attracts the charging cockpit.
Remove the magnet.
Take out the transparent plastic part that secures the battery.
A close-up of the pressure relief hole at the back cavity, with a dust screen inside.
This FPC is connected to the button battery and the other in-ear detection FPC. There is a speaker unit connector and a lithium battery protection IC on the middle small board.
The other side of the FPC is connected to the motherboard through the BTB connector.
Silkscreen XCAA DEKJ’s integrated lithium battery protection IC.
The magnet side of the speaker unit is sealed with a lot of red glue, and there is a tuning hole on the side.
There are also positioning points for installing FPC on the outside of the T iron, which is convenient for factory assembly.
The speaker unit size is about 10mm.
The internal structure of the front cavity of the earphone is complete.
All components of Huawei FreeBuds 4i wireless earphones.
The charging case of Huawei FreeBuds 4i wireless earphones adopts a cobblestone shape. The earphones are designed with a handle-in-ear design. The surface of the shell is treated with piano paint to enhance the sense of quality; the size of the headphones and charging case is smaller than that of Huawei FreeBuds 3 and FreeBuds Pro , Comfortable to wear and more portable.
Huawei officially did not advertise the waterproof capability of this product, but 52audio discovered during the disassembly process that both Huawei FreeBuds 4i earphones and charging cases have perfect waterproof measures, and the details are no less than flagship products: charging case buttons, charging The interface, indicator light and charging cockpit have corresponding dustproof and waterproof designs; there are a large amount of sealing glue at the joints of the front cavity of the earphone, the charging contacts, the microphone pickup hole, etc. Production and testing have increased the difficulty.
In terms of internal circuits, the charging case inputs power through the USB Type-C interface, Willsemi’s TVS is used for input over-voltage protection, and the battery charging and discharging management circuit uses more customized chips. ETAsolutions ETA1061 is responsible for boosting the battery output to charge the earphones, and GigaDevice’s The MCU is used for the function control of the charging case; the capacity of the soft pack battery is 215mAh. In the charging case, there is a plastic middle frame to fix the internal circuit, which plays a role of structural strengthening, which correspondingly affects the size of the battery and the addition of wireless charging modules. The latter may also be the reason for product positioning.
In the earphone part, the main control chip of Huawei FreeBuds 4i is BES BES2500Z, which supports active noise reduction and environmental sound transmission, and supports bluetooth 5.2 standard; the earphone active noise reduction uses a feedforward noise reduction solution, and the call noise reduction uses dual microphone beamforming Technology, sound hole position and structural design are unique to reduce wind noise; the earphones transmits bluetooth signals through the on-board antenna, the capacitive in-ear detection and touch 2-in-1 solution comes from GOODiX, and the button battery capacity is 55mAh.
From the perspective of disassembly, the internal circuits of Huawei FreeBuds 4i earphones and charging case are basically connected and fixed by means of FPC, BTB connector and glue, which is conducive to improving production efficiency; the internal space of the earphones and charging case is compact, and the overall structure design is better.