The Redmi AirDots 3 Pro true wireless headphone is the first noise-canceling headset product launched at the Redmi Note 10 series “flagship core, Xiaojingang” new product launch conference on May 26. It adopts a brand-new design scheme and a combination of functions. A comprehensive upgrade has been carried out.
The appearance of the Redmi AirDots 3 Pro true wireless noise-cancelling earphones, the charging case adopts a vertical oval shape, with a silicone-like touch. The earphones continue the bean-shaped in-ear design, and the back of the earphones is designed with a touch back panel similar to spar. The overall texture of the headset has been greatly improved; in terms of functions, active noise reduction, adaptive noise reduction, transparent mode, dual device connection, wireless charging, etc. have been added.
52audio has previously disassembled Xiaomi FlipBuds Pro, Xiaomi Air 2 Pro, Xiaomi Air 2 SE, Xiaomi Air 2S, Xiaomi Air 2, Redmi AirDots 3, Redmi AirDots 2, Redmi AirDots, and Xiaomi 6 bluetooth speakers product. Let’s take a look at the internal structure configuration of this product.
| 1. Redmi AirDots 3 Pro Charging case teardown
After unpacking, we have a general understanding of the appearance of the Redmi AirDots 3 Pro true wireless noise-cancelling earphones. Let’s enter the disassembly part to take a look at the internal structure design and configuration of this product!
Pry open the charging case.
Charging case The indicator light inside the shell is special for the light guide.
The Type-C charging interface decorative ring at the bottom of the shell is fixed on the shell.
The inner structure of the function button keycap is special.
Charging case There is a wireless charging coil on the back of the cockpit.
The charging case is on the front of the cockpit, and the cockpit shell is also provided with a structure of function keys.
The internal cockpit housing is fixed by screws.
Remove the screws and take off the shell.
Inside structure of cockpit cover.
Remove the other side of the structure, there is a small charging board and multiple magnets at the bottom of the cockpit.
Charging case cover structure.
Remove the charging plate, there are a total of 5 magnets at the bottom of the cockpit, which are used to absorb the earphones and the charging case cover.
The front circuit of the charging board.
The circuit on the back of the charging board.
The pogo pin used to charge the earphone.
The status indicator light is provided with a black rubber cover to guide light.
Two LED indicators of different colors.
The silk-screened HBAH Hall element, by sensing the magnetic field change (Hall effect) when the charging case cover is opened/closed, notifies the charging case MCU, and then informs the headset to connect/disconnect with the paired device, realizing the function of opening and closing the cover.
There is a thermistor on the cable connected to the motherboard to detect the battery temperature.
The main circuit inside the charging case.
A close-up of the wireless charging receiving coil, with a shielding sticker underneath.
Charging case Built-in lithium-ion polymer soft pack battery model: EVE821828BH, rated capacity: 470mAh/1.79Wh, rated voltage 3.8V.
The front of the battery circuit board.
The back of the battery circuit board is connected to the main board through a wire.
The circuit on the front of the motherboard.
The circuit on the back of the motherboard.
The Bluetooth pairing function button on the motherboard.
The bottom of the Type-C charging interface socket is engraved with the ZMI LOGO.
22μF 16V filter capacitor.
Sinhmicro SS881Q-W, a low-power MCU chip integrated with a wireless charging RX controller, adopts a QFN 4×4 package to save space, and can be widely used in various smart hardware devices with wireless charging reception and battery charging and discharging management.
SS881X-W series built-in wireless charging RX end compatible with Qi protocol communication source coding module and wireless charging power adaptive control module (support Qi certification), as well as linear charging unit and power management unit, at the same time has a wealth of interface functions, flexible The configuration mode, and different low-power options.
52audio learned that there are already products of OPPO, 1More, 233621, Anker, realme, Edifier, ZMI, FIIL, Skullcandy, Lenovo, Nubia, Philips and other brands that have adopted Sinhmicro TWS charging case MCU chips.
SILERGY silk screen yDAWA IC.
ETAsolutions ETA7014 overvoltage and overcurrent protection IC.
Details of ETAsolutions ETA7014.
The lithium battery protection IC XB5152J2SZR of Suzhou Saixin Electronic Technology Co., Ltd.
NuVolta NU1680C wireless charging receiver chip is a highly integrated wireless power receiver. It integrates a synchronous rectifier, does not need a bootstrap capacitor, has the characteristics of high efficiency and low cost; and can adjust the output voltage to track the battery voltage, further reducing the power consumption of the charging system.
NU1680C can communicate with the transmitter system through ASK, and the communication conforms to WPC V1.2.4. FOD parameters can be configured through external resistors to pass the FOD test. NU1680C also supports standard protection functions such as over-current protection, short-circuit protection, over-voltage protection and thermal shutdown.
The main board and battery wires are welded, and the solder joints are glued to reinforce.
| 2. Redmi AirDots 3 Pro earbuds teardown
Into the disassembly part of the earphone, first remove the touch back panel and pry open the cavity along the mold line.
The front of the back panel is designed like spar.
The back is pasted with a texture layer to make it show different gloss look at different angles.
Below the back panel is the touchpad and Bluetooth antenna.
The touch sensor and the LDS Bluetooth antenna are set on a plastic board.
A close-up on the back of the plastic board, and the Bluetooth antenna is connected to the motherboard through two contacts.
The main board unit is conveniently under the plastic board.
Open the cable BTB connector and remove the motherboard.
The internal structure of the cavity.
ST MEMS bone conduction voice switch LIS2DW12. In addition to supporting tapping, it also supports VAD’s voice switch, which uses vibration to determine whether the keyword is spoken by the person, reducing false triggers caused by other people’s keywords in the environment.
According to 52audio, the flagship TWS headsets of brands including Apple, Amazon, Samsung, Xiaomi, and vivo all use ST sensors.
The flat cable passes through the rear cavity and is connected to the small plate of the front cavity.
The speaker unit in the front cavity is welded on a “U”-shaped PCB small board.
The cable extending from the main board is connected to the small board through the BTB connector.
Open the connector to separate the front and rear cavities.
Melt the tin point, open the BTB connector of the in-ear detection sensor, and remove the U-shaped small board.
On the front of the small board, there are two BTB connectors to connect the main board and the in-ear detection sensor, and the speaker and charging contacts are welded on the small board.
On the back of the small board, two round solder joints are used to solder the charging contacts.
Remove the speaker, the internal structure of the cavity is at a glance. A dust-proof net is affixed inside the pressure relief hole.
On the other side, a rear-feed noise reduction microphone is installed, which is connected to the ear detection sensor on a cable.
The special-shaped magnet in the cavity is used for adsorption with the charging case.
A total of two magnets are installed in the headset to improve the adsorption stability.
The capacitive in-ear detection sensor is attached to the cavity wall, and the silk-screen information H-21071.
The back of the speaker unit.
The front of the speaker unit uses a composite diaphragm.
After actual measurement, the size of the speaker unit is about 9mm, which is consistent with the official publicity.
Remove the plastic fixing frame in the rear cavity.
Remove the button battery.
The internal structure of the cavity.
The pressure relief hole inside the cavity is covered by a fine dust-proof net.
The back of the button battery has a capacity of 35mAh 0.135Wh.
The front of the button battery, the voltage is 3.85V, from EVE Lithium Energy.
The main control chip and microphone are set on the front of the motherboard.
The back of the motherboard.
Metal shrapnel connected with LDS antenna.
The MEMS silicon microphone of LaserDiao S259 is used for noise reduction function.
Another MEMS silicon microphone used for voice call pickup is of the same specification.
ABOV modern microcontroller A96T346 capacitive touch MCU.
The main control chip is AIROHA AB1565AM Bluetooth audio SoC. AB1565x is Airoha’s new generation Bluetooth advanced audio solution, equipped with the latest BT5.2, capable of supporting LE audio. The latest multi-point for TWS, which can be connected to a notebook and a mobile phone at the same time and easily switch; provides ultra-low power consumption and ultra-low latency performance, with an average power consumption of ~4.x mA, which is currently the leading power consumption in the bluetooth audio market Standard; also has a stable Bluetooth connection and clear sound quality and Hybrid active noise reduction function, providing rich and powerful performance for bluetooth headphones.
Airoha AB1565x has built-in CM4 processor and Tensilica HiFi mini DSP on the hardware, embedded 4MB/8MB flash memory, integrated lithium battery charge controller and power management integrated circuit, and provides a variety of flexible package sizes and other options. In terms of software, it supports Google/AMA/Siri, etc., and provides IOS and Android reference APP development and design.
According to 52audio, Bluetooth headsets from brands such as Sony, Huami, 1More, realme, FIIL, Edifier, and Plantronics have adopted Airoha solutions in large numbers.
AIROHA AB1565X frame diagram.
All components of Redmi Buds 3 Pro true wireless noise canceling headphones.
| 3. Summary
Redmi AirDots 3 Pro true wireless noise-cancelling earphones have a very small and exquisite appearance in the design of the charging case. It adopts a vertical oval shape, which is easy to open the cover with one hand. Both the charging case and the earphone are treated with a silicone-like process. , It is very comfortable and skin-friendly to hold and wear. The crystal-like design on the back of the headset presents different light perceptions at different angles, which improves the texture and recognition of the product.
The internal structure design of the charging case is very regular. After the shell is removed, a plastic frame is set inside, and the wireless charging receiving coil is located on the outer layer of the frame. A battery, a main board unit and a small board for charging the headset are arranged inside the frame, and the two PCB boards are connected through a flat cable and a BTB connector.
The motherboard adopts Type-C interface input power, Sinhmicro SS881Q-W integrates wireless charging RX controller low-power MCU chip, used for battery charging and discharging management and whole machine control; wireless charging receiving chip uses highly integrated NuVolta NU1680C Wireless power receiver, supports over current, short circuit, over voltage protection and thermal shutdown, etc.
The internal structure of the Redmi AirDots 3 Pro headphone is relatively complicated. The plastic plate below the earphone back panel is provided with a touch sensor and an LDS Bluetooth antenna, and below it is the main board unit. An isolation layer is arranged between the main board, the battery and the speaker cavity, and is connected through an FPC cable. The ST LIS2DW12 MEMS bone conduction voice switch is installed on the cable for the voice hot word control function.
The speaker and charging contacts in the front cavity of the Redmi AirDots 3 Pro earphones are welded on the U-shaped adapter board. Two BTB connectors on the small board are connected to the ear detection sensor and the motherboard; a steel shell button battery is placed in the back cavity with a capacity of 35mAh. EVE; On the motherboard, the main control chip uses Airoha AB1565AM new generation Bluetooth advanced audio solutions, equipped with the latest BT 5.2 and LE audio, providing ultra-low power performance, stable Bluetooth connection and clear sound quality and Hybrid active Noise reduction function; there is also a modern single-chip A96T346 capacitive touch MCU for touch operation control and so on.