On October 13th, Xiaomi Air 2 Pro true wireless bluetooth earphones was directly released online and opened for pre-sale in all channels. This is Xiaomi’s first true wireless noise reduction earphones. The official promotion is that it supports “wideband active noise reduction” and adopts hybrid noise reduction. Solution, the noise reduction depth can reach up to 35dB.
In terms of configuration, Xiaomi Air 2 Pro true wireless bluetooth earphones uses a low-power bluetooth chip, supports LHDC 3.0 high-definition bluetooth decoding technology (subsequent OTA upgrade support) and MIUI system LLAC low-latency transmission technology, the official promotion delay can be shortened to less than 100ms ; The earphone has a built-in high-rigidity LCP liquid crystal composite diaphragm and a 12mm large-size dynamic unit, which is tuned by the Grammy master and world-class musician Luca Bignardi; the charging case supports the Qi wireless charging standard, and the earphone and charging case support fast charging , It can play music for 90 minutes after charging for 10 minutes (ANC is off), and the battery life is about 7 hours when the active noise reduction is turned off. The total battery life can reach 28 hours with the charging case.
The appearance of the Xiaomi Air 2 Pro earphones has changed significantly compared with the products of the same series. The shell has a larger curvature, the earphone handle is more slender, the earphone touch area is designed with a bright surface, and the official promotion uses ceramic processing. However, just like the previous Air series only has white, Air 2 Pro has only black one color. What are the upgrades in the internal design and materials of this product? Let’s take a look at the detailed disassembly of 52audio!
There are more disassembly of Xiaomi audio products: Xiaomi HiFi decoding amp (quick charge version), Xiaomi Art smart speaker, Xiaomi PRO 8 touch screen speaker, Redmi Play smart speaker, Xiaomi wireless charging bluetooth speaker, Xiaomi Pro speaker, Xiaomi MINI outdoor bluetooth speakers, etc.
01/ Xiaomi Air 2 Pro charging case teardown
After the previous unboxing, I believe everyone has a preliminary impression of the appearance design of the Xiaomi Air 2 Pro true wireless bluetooth earphones, which is in the same line as the previous design voice and is relatively simple. Let’s first disassemble the charging case to see what solutions are adopted by its wired charging power management system and wireless charging power management system.
Pry open the charging cockpit and fix it with multiple physical buckles.
Take out the charging cockpit.
On the inside of the charging cockpit, there is a triangular magnet at the opening of the lid, which is used to absorb the lid and the function of opening the lid. There is also a magnet on the left and right earphone placement positions to fix the earphones.
The internal structure of the charging case has a plastic middle frame to fix the motherboard and battery.
Remove the charging case cover.
The spring structure design at the metal hinge.
Internal structure display of charging case.
Shield sticker on metal hinge.
Shield the other side of the sticker.
Take out the plastic middle frame in the charging case.
The wireless charging receiving coil is pasted on the inside of the box.
Take out the wireless charging receiver coil.
The structural design of the matching button, the button is stuck inside the shell to improve the stability.
The protective cover for the front indicator of the charging case.
Internal structure display of charging case.
The internal structure of the charging case is shown on the other side.
The bottom of the internal structure of the charging case is displayed, and the PCBA at the bottom is fixed by heat-melting the shell plastic column to simplify the assembly process.
Internal circuit display of charging case.
An FPC in the charging case is connected to the internal circuit.
A close-up of the LED indicator, used for charging case status indication, with a circle of black foam on the outside to avoid light leakage.
A close-up of the micro-motion buttons on the side of the fuselage.
For the Hall element of silk-screened AEOM1, the magnetic field changes when the charging case cover is opened and closed will be sensed by the Hall element, and then the charging case MCU and earphone are notified to pair or disconnect with the connected device.
Display inside the plastic middle frame.
The main circuit inside the charging case is displayed.
The charging case internal circuit is displayed on the other side.
The charging case motherboard circuit display, this side is the MCU related circuit.
The charging case motherboard circuit is shown on the other side, the upper right corner is the wireless charging receiving circuit, and the lower right corner is the wired charging management circuit. Let’s first look at the wired input part.
Shanghai WillSEMI WS3210C over-voltage protection switch, when the input voltage exceeds 5.85V, the output will be turned off, and the maximum withstand voltage is greater than 80V, protecting the downstream components from damage due to overvoltage breakdown.
SILERGY SY6918B, a high-efficiency two-way charging and discharging power management chip, supports path management, with a maximum input voltage of 18V, QFN3x3 package saves PCB area and is used for internal battery charging.
The charging case uses a soft pack battery, from AEC, model AEC742425, with a rated capacity of 500mAh and an output voltage of 3.8V.
A close-up of the battery protection board, with battery protection IC and 8205 MOS tube.
There is a shielding sticker between the wireless charging receiving coil and the motherboard circuit. The transmitting coil of the wireless charger generates a certain current in the receiving coil through electromagnetic induction effect based on a certain frequency of alternating current, thereby transferring electrical energy from the transmitting end to the receiving end, and then powering the battery in the TWS charging case.
A close-up of the wireless charging receiving coil, multiple strands of enameled wire wound together. The part connected with the main board is insulated with a heat shrinkable tube.
Resonant capacitor for wireless charging and receiving.
ConvenientPower CPS3039 is an efficient, Qi standard wireless power receiving and charging management chip. It integrates a receiving module and a linear charging module, and supports up to 5W output, suitable for low-power battery-powered applications such as TWS earphones.
ConvenientPower CPS3039 integrates a low RDS (ON) full-bridge synchronous rectifier circuit to convert the AC energy signal received from wireless charging. CPS3039 integrates an MCU and on-chip memory to provide user programmability, and advanced power management circuits to achieve extremely low standby power. CPS3039 integrates accurate fault protection circuits: including over-temperature, over-current, and over-current voltage protection to ensure safe operation.
SILERGY SY7069 high-efficiency 3A output synchronous rectification boost converter, used for charging case built-in battery boost to charge earphones.
WillSEMI WS4612 load switch with current limit function, adjustable protection current, used for earphone charging overcurrent protection.
WillSEMI WPM3401 PMOS tube.
Two silkscreen S7R ICs.
Holtek HT50F32002, a 32-bit high-performance low-power MCU based on Arm® Cortex®-M0+ processor core. This series of single-chip microcomputers can work at frequencies up to 20 MHz, with the help of Flash accelerators to obtain maximum performance. It provides up to 32 KB of embedded Flash memory for program/data storage, and up to 4 KB of embedded SRAM memory for system operation and application application, and is used for whole machine control of charging cases.
The PCBA where the Pogo Pin for charging the earphones is located is connected to the motherboard through the FPC.
Display on the other side of PCBA.
Pogo Pin for charging earphones.
The hall element of the silk-screened AD OM is used to more accurately detect whether the earphones is placed in the charging case. On the right is the TVS for electrostatic protection.
02/ Xiaomi Air 2 Pro earbuds teardown
Xiaomi Air 2 Pro supports “wideband active noise reduction” and adopts a hybrid noise reduction scheme. The design position of the feedforward microphone on the official promotional map is unique. There are three microphones in the earphones that work at the same time for the noise reduction function. Let’s take a look at how the interior of the earphones is designed.
The Mi Air 2 Pro true wireless bluetooth earphones adopts a handle-in-ear design, and its appearance has been greatly changed compared with the previous Air 2 series. The earphone handle is more slender, and the shell lines are smoother and more natural.
The touch area of the earphone is designed with a bright surface. The official promotion uses ceramic technology, which has a delicate texture and is relatively wear-resistant, which contrasts with the matte texture of the shell. Long press the touch area to switch between noise reduction mode and transparent mode.
The opening of the feedforward microphone is mainly used to pick up ambient sound.
The strip pressure relief hole on the earphone shell adopts metal dust-proof net.
The infrared distance sensor opens the window for the ear detection function, and realizes the automatic play/pause of music.
The tuning hole in the sound cavity is also the pickup hole of the feedback microphone.
Metal dust-proof net at the sound mouth.
The silver charging contacts at the bottom of the earphones and the sound pickup hole of the call microphone.
The disassembly of the handle earphone starts from the seam of the earphone shell and the bottom of the earphone handle.
Disassemble the ear shell along the parting line, and fix it with buckle and glue.
Inside the structure where the earphone enters the ear is a button battery.
There is a layer of insulating soft film outside the button cell.
Information on the soft film, EM028 Tiinlab V2.
Show on the other side of the soft film.
The sound chamber is an independently sealed structure.
There is a PCBA between the touch sensing area and the battery, and there is a reinforced metal sheet on this side.
Remove this PCBA, you can see the internal structure.
The strip-shaped motherboard circuit is connected with the battery and the internal circuit of the sound cavity through the FPC and the connector.
Below the FPC is the touch pad, which is integrated with the circular PCBA.
Remove the sealant.
Sensor foil for touch detection.
Display inside the touch area.
Pull out the motherboard from the bottom of the earphone handle.
The main board is shown on the side, which is connected to the battery and speakers in the sound cavity through FPC and connectors.
Circuit display on the motherboard side.
There is a large amount of sealant in the bottom structure of the earphone handle.
Laser carving Z 05619 MEMS silicon microphone.
A close-up of the inside of the charging contacts.
The circuit is shown on the side of the motherboard, and the top is the feedforward microphone.
The circuit on the other side of the motherboard is shown, the top is the pickup hole of the feedforward microphone, and the main control chip is under the QR code sticker.
The protective cover for the sound pickup hole of the feedforward microphone improves airtightness and sound pickup ability, with L/R left and right marks on it.
Disassemble this protective cover.
The protective cover is a snap design, not fixed by glue.
A close-up of the dust net on the protective cover, with a digital code inside.
Laser carving Z D5619 MEMS silicon microphone.
The earphones uses a ceramic patch bluetooth antenna for data transmission.
Hanxin Micro HP4554 Lithium battery charging IC with high voltage input, simplified peripheral components, input protection voltage 6.8V, maximum withstand voltage 24V.
The regulator IC of silk screen AMYy.
Silkscreen 59 IC.
Silkscreen 73Z IC.
The bluetooth master chip of the Mi Air 2 Pro earphones is Bestechnic BES2300YP. BES2300 is a fully integrated adaptive active noise reduction solution that supports bluetooth 5.0, IBRT low-frequency forwarding technology and dual-mode bluetooth 4.2. It also supports the third generation of FWS full wireless stereo technology, dual microphones, etc., using 28nm process, BGA package.
Bestechnic BES2300 supports noise reduction technology, especially high-performance adaptive active noise reduction technology, which allows high-end active noise reduction earphones to use a fully integrated chip to achieve high sound quality and active noise reduction. BES2300 also supports external heart rate sensors, acceleration sensors, and other external sensor devices and eMMC flash memory, which can achieve the purpose of playing music on external storage devices; BES2300 can also output sound to earphones and home audio, or record from an external microphone.
52audio learned that a large number of true wireless headsets from brands such as Huawei, Xiaomi, OPPO, JBL, Honor, Baidu, OnePlus, and Transsion have adopted Bestechnic solutions.
The speaker unit is connected to the circular PCBA through the FPC, and the button battery is connected through a wire.
Connect the connector socket of the strip FPC.
On the other side is a reinforced metal sheet.
ST MEMS bone conduction voice switch LIS2DW12. In addition to supporting tapping, it also supports VAD’s voice switch to determine whether keywords are spoken by the person through vibration, reducing false triggers caused by keywords of other people in the environment.
According to 52audio, flagship TWS earphones of brands including Apple, Amazon, Samsung, Xiaomi, and vivo all use ST bone conduction sensors.
Silk screen AD0R1 IC.
Silkscreen 6096I0x is XYSEMI DFN2X2 lithium battery protection IC, which provides safe and reliable all-round protection for TWS.
According to 52audio, there are already many well-known brands of TWS headset products such as QCY, Redmi, Sony Ericsson, Pemeter, Meizu, Go Ask, Edifier, Honor, etc., using a large number of Saixin’s lithium battery protection ICs.
The CellWise CW2015 fuel gauge chip can accurately estimate the remaining battery power and display the battery power in the pop-up window.
According to 52audio, a variety of earphones including Huawei FreeLace Pro noise reduction neckband bluetooth earphones, Xiaomi Air 2s true wireless bluetooth earphones, Honor Flypods 3 true wireless active noise reduction earphones, Xiaomi Air 2 true wireless bluetooth earphones, etc. all use CellWise power计chip.
The silk screen A2A4 is Holtek’s ZHUOXINWEI customized MCU, which is used in TWS wear detection and functional touch buttons. It has ultra-low power consumption and updated sensitivity through bluetooth.
There is a layer of insulating plastic outside the button cell. Button battery capacity 55mAh/0.204Wh, rated voltage 3.7V, model LIR ZJ1254C 20B, diameter 12mm, thickness 5.4mm.
The button battery supplier is from Chongqing VDL Electronics Co., Ltd, with a charging limit voltage of 4.2V.
According to 52audio, well-known brands such as Huawei, Xiaomi, Meizu, and OPPO have adopted a large number of batteries from Chongqing VDL Electronics Co., Ltd.
The bar magnet that attracts the charging cockpit.
The internal structure of the sound cavity is displayed.
T iron of the speaker unit.
A close-up of the speaker unit diaphragm, which is officially advertised as a high-rigidity LCP liquid crystal composite diaphragm, which was deformed and disassembled.
The sound pickup hole of the rear-feed microphone has an infrared distance sensor inside, which is sealed separately.
A close-up of the infrared distance sensor opening the window.
The internal circuit of the earphones is shown.
The internal circuit of the earphones is shown on the other side.
Close-up of infrared distance sensor and feed-back microphone.
The size of the moving coil unit is about 12mm, which is consistent with the official publicity.
All parts disassembled.
03/ Summary
The appearance of the charging case of the XiaoMi Air 2 Pro true wireless bluetooth earphones is similar to the previous one, with a similar style and larger size, mainly due to the increase in battery capacity; the earphones still uses a handle in-ear design, but the handle of the earphones is more slender and the shell is linear It is more smooth and natural. The earphone touch area is designed with a bright surface, which contrasts with the matte texture of the shell. The overall appearance design is simple and durable, and the earphone color is only black.
In terms of internal circuits, the PCBA and FPC of the Xiaomi Air 2 Pro earphones and charging case are all in uniform black. The metal hinge position of the charging case, the wireless charging receiving coil, the inner battery of the earphone and each cavity are all added with shielding stickers. , Reduce electromagnetic interference; the internal circuit of the earphones is combined with the soft and hard board, and the two parts of the circuit are connected through the FPC, which can improve the efficiency of factory assembly. The overall design and workmanship are excellent. This product is foundry by 1MORE Acoustic Technology Co., Ltd. (Xiaomi Eco-chain Enterprise). The “Tiinlab” logo on the internal circuits of the earphones and charging case is the “TiinLab Listening Lab” established by the merger of the 1MORE Acoustics Center and the TiinLab brand.
The charging case supports Qi standard wireless charging. The wireless charging receiving solution is ConvenientPower CPS3039, which integrates a receiving module and a linear charging module, and supports up to 5W output to charge the built-in battery; the wired charging part, Type-C interface input power, provided by WillSEMI WS3210C Input overvoltage protection, SILERGY SY6918B power management chip is responsible for battery charging and discharging; charging case soft pack battery comes from AEC with a capacity of 500mAh; battery output is boosted by SILERGY SY7069 for earphone charging, WillSEMI WS4612 provides overcurrent protection for earphone charging; Holtek HT50F32002 The MCU is responsible for the overall control of the charging case. A total of three Hall elements on the circuit are used to accurately detect the status of the earphones and the charging case.
The main control chip of the XiaoMi Air 2 Pro true wireless bluetooth earphones is Bestechnic BES2300YP, which supports active noise reduction and adopts a hybrid noise reduction scheme. The feedforward microphone is designed on the front side of the earphones when the earphones is worn, and the rear feed microphone is located near the sound outlet. At the same time, there is also a call microphone at the bottom of the earphone handle, which can be reused for the front and rear feed microphones for call noise reduction.
The earphones uses a button battery from Chongqing VDL Electronics Co., Ltd with a capacity of 55mAh, which makes full use of space; the internal charging IC uses HYPWR HP4554, XYSEMI DFN2X2 lithium protection IC provides battery protection, and CellWise CW2015 performs battery fuel gauge. There is also an infrared distance sensor in the earphone for in-ear detection, which supports touch control and is controlled by ZHOUXINWEI customized Holtek MCU; ST MEMS bone conduction voice switch is used for voice wake-up function; on the acoustic configuration, a 12mm moving coil unit supplemented by a high-rigidity LCP The LCD composite diaphragm enhances the sense of hearing.
From the disassembly of the hardware level, the Xiaomi Air 2 Pro true wireless bluetooth earphones has a significant improvement in technology compared with the previous generation, and the overall design and materials have few rivals in the same price product. In addition, the earphones has pop-up windows for use with Xiaomi mobile phones, supports LLAC low-latency transmission technology, and will be upgraded to LHDC 3.0 high-definition bluetooth decoding. It is Xiaomi’s latest flagship TWS earphones.
Source:52audio
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