Looking back on 2021, Xiaomi changed its product positioning plan in the TWS headset market, and successively launched three products: Xiaomi FlipBuds Pro, Xiaomi Buds 3 Pro and Xiaomi Buds 3 true wireless noise cancelling earbuds. They all focus on the mid-to-high-end market, with uniquely recognizable brand characteristics and rich functional experience.
The Xiaomi Buds 3 true wireless noise cancelling earbuds are the latest generation of Xiaomi products. As a sinking model, the appearance continues the design style of the Xiaomi TWS headphones family in 2021, with very high recognition and good texture performance. The handle-shaped in-ear design similar to the musical note has smooth and graceful lines, and is light and comfortable to wear.
In terms of functions, it still focuses on HiFi-level sound quality and ANC, supports 40dB depth noise cancelling (authoritative test of China Metrology Institute), and has three-speed adjustable noise cancelling and dual transparency modes. It also supports 3-mic call noise cancelling, pressure-sensitive control, wireless charging, etc. Compared with Xiaomi Buds 3 Pro, the difference is that the adaptive active noise cancelling function, 360° surround sound field spatial audio and LHDC4.0 audio decoding are cancelled.
52audio previously teardowned Xiaomi’s products including: Xiaomi Buds 3 Pro earbuds, Xiaomi FlipBuds Pro earbuds, Xiaomi Air 2 Pro, Xiaomi Air 2 SE, Xiaomi Air 2S, Xiaomi Air 2, Redmi AirDots 3 Pro, Redmi AirDots 3, Redmi AirDots 2 and Redmi AirDots etc. Let’s take a look at the internal structure of this product.
|1. Xiaomi Buds 3 charging case teardown
After unpacking, we got to know the design of this product. Enter the teardown section below to see the internal structure configuration information.
Pry up the charging case earphone cockpit, and the cable connecting the earphone charging board is fixed on the cockpit.
The motherboard extension cable is connected to the bottom of the cockpit through a ZIF connector.
The bottom structure of the cable cockpit is removed, and an FPC cable is connected in series with a small board for charging the earphones at both ends. There are three bar magnets at the bottom of the cockpit for attaching the charging case cover and earbuds.
Two pogo pin connectors for charging earphones.
A separate frame is also arranged in the charging case cavity for fixing the main components in the charging case.
Take out the internal components of the charging case.
Type-C charging interface and function button keycap structure.
The main components inside the charging case.
The wireless charging receiving coil is fixed on the magnetic shielding sticker, and pasted on the inside of the charging case shell through double-sided tape.
The top of the bracket holds the motherboard unit with screws.
The battery power supply is set in the “intra-abdominal” bracket, which plays a very good protective role.
There is an FPC cable on the front, a series indicator light and a Hall element.
Remove the screws and remove the motherboard.
There is also a thermistor at the end of the FPC cable, which is attached to the battery to detect the battery temperature.
FPC wiring circuit.
The hall element of the silk-screen AR1S1 is used to sense the change of the magnetic field when the charging case opens and closes the cover, and notifies the charging case MCU and earphones to pair or disconnect with the connected device.
Three LED indicators of different colors, and black foam is set on the periphery to prevent light leakage.
The battery cell wires are soldered to the motherboard.
Information on the label of the lithium-ion polymer battery inside the charging case, model: BW51, rated capacity: 480mAh/1.82Wh, nominal voltage: 3.8V, charging limit voltage: 4.35V.
Manufacturer: Dongguan Liwinon Energy Technology Co., Ltd., Made in China.
Tear off the label, the silk screen information on the cell is consistent with the external label. The battery is not provided with an independent circuit protection board, and the protection circuit is located on the main board.
The circuit on one side of the charging case motherboard.
The circuit on the other side of the charging case motherboard.
The function buttons on the motherboard are used for bluetooth pairing connection.
Type-C charging interface female socket.
The ZIF connector on the motherboard to connect the cable.
COPO CP2022 is a single-chip, advanced, flexible, secondary-side wireless charging transmission chip, which can provide up to 3W of power for portable applications. It has the advantages of high integration, high efficiency, and low power consumption. It complies with Qi V1.2.4 standard. On the outside of the chip are the resonant capacitors and filter capacitors for wireless charging reception.
According to 52audio, COPO’s wireless charging receiving solution has been widely adopted by Xiaomi, OPPO, Edifier, Baseus, Sabbat, realme, omthing, iWALK, TOZO and other brands of TWS headphones.
LPS LP6261A 1uA low power boost chip. The switch pin adopts a high-voltage 9V process, which can effectively absorb the high-voltage spike generated when the earphone is plugged and unplugged. At the same time, LP6261A has no whistling sound in full load capacity (especially light load).
LP6261A adopts SOT23-6 package, 1.7uA ultra-low power boost (when 5V is normally open), and the output voltage is adjustable. Shutdown current <0.1uA, built-in EN completely shut down, built-in output short-circuit protection.
According to 52audio, a large number of audio products from Xiaomi, OPPO, OnePlus, realme, Transsion, MEIZU, Lenovo, Edifier, 1MORE, QCY, Baidu, JBL, Marshall and other brands have adopted the LPS power management solution.
Silkscreen 2R2 inductor, with boost chip boost to charge the earphones.
SinhMicro SS881E POWER MCU, using SSOP24 package, integrates battery charging management and single chip microcomputer, and realizes functions such as power management and charging case control.
SS881X is SinhMicro’s AD-type Flash MCU series integrated with charge and discharge management. It has built-in rich interface functions, flexible configuration modes and different low-power options. This product is mainly used in portable intelligent electronic devices that require charging and intelligent control, bringing streamlined peripheral costs, excellent performance and flexible and convenient development.
According to 52audio, including Xiaomi, OPPO, 1MORE, Edifier, Redmi, ZMI, realme, FIIL, Anker, Lenovo, LINNER, Astrotec, Nubia, Razer, HTC, Soundcore, JBL, UGREEN and other brands Many TWS headphone charging cases have adopted the SinhMicro solution in large numbers.
The TVS of M24A is silk-screened on the back of the Type-C interface for input overvoltage protection.
Prisemi P14C1N overvoltage and overcurrent protection IC, withstand voltage up to 32V, overvoltage fixed 6V. The peripheral resistance of the overcurrent protection point is adjustable, the overcurrent response time is adjustable, and the overcurrent protection accuracy is 10ma, which can meet the overcurrent protection requirements of various adapters and various projects.
According to 52audio, a number of TWS earphone products under brands including OnePlus and Soundcore have adopted Prisemi power management chips in large numbers.
XySemi XB5152J2SZR lithium battery protection IC with reverse load connection.
|2. Xiaomi Buds 3 earbuds teardown
Go to the earphones teardown section. Pry open the cavity along the parting line, and there are cable connections between the front and rear cavities.
The inside of the front cavity is covered by white brackets and a lot of white glue, forming an independent cavity structure to avoid electromagnetic interference. A battery unit is arranged in the rear cavity.
The noise cancelling microphone is fixed at the bottom of the rear cavity, and the components in the headphone head are connected to the motherboard through cables and BTB.
Remove the white bracket, the internal structure of the anterior cavity.
Take out the speaker, and an inward noise cancelling microphone is set inside the sound cavity.
Remove all components from the anterior chamber.
The internal structure of the front cavity and the inside of the pressure relief hole are provided with a fine dust-proof net for protection.
The magnet on the inner cavity wall of the rear cavity is used to adsorb the charging case cockpit.
The circuit on the component side of the headphone head.
The circuit on the other side of the component inside the headphone head.
Laser carving N 14N95’s MEMS noise cancelling microphone is used to pick up external environmental noise.
Laser carving M1 1AW26’s inward noise cancelling microphone is used to pick up the noise inside the ear canal.
Capacitive in-ear detection patch.
The circuit on the back of the battery.
Silkscreen 16 ICs.
Silkscreen IC of 1c ox.
The front of the speaker unit. The ultra-dynamic dual-magnetic unit used is composed of N52 dual-magnet, Japanese big black CCAW coil and high-rigidity diaphragm, which can effectively reduce the distortion rate, improve the frequency response, and reduce high-frequency split vibration.
The back of the speaker unit.
After actual measurement, the size of the dynamic driver is about 10mm.
The inside of the earphone uses a soft-pack button battery, the outside is wrapped in a black plastic shell, and there is a QR code on the top.
The positive and negative electrodes on the back of the battery are connected by spot welding.
Remove the back cover of the earphone handle, and there is also a bracket below to fix the internal motherboard.
Headphone microphone sound hole.
Noise cancelling microphone sound hole.
The circuit on the side of the headphone motherboard.
The circuit on the other side of the headphone motherboard.
Laser engraving N 15E87’s MEMS microphone for voice pickup.
Silkscreen AMCJ’s IC.
The pressure sensing sensor is fixed on the main board and is used for various function control.
CHIPSEA CSU18M68 pressure sensor detection IC is a SOC with dual-channel pressure sensor measurement function, which can be used in mobile phones, wearables, notebooks, industry, home appliances and other fields, and supports AFE mode and MCU mode.
According to 52audio, TWS headphones of Zepp Health Corporation, vivo, Redmi, UGREEN, ZMI, Philips, 1MORE and other brands have adopted CHIPSEA chip products. It is reported that CHIPSEA Technology has recently launched the CSA37F72 three-in-one (in-ear, sliding, pressing) SoC chip.
Headphone ceramic bluetooth antenna for wireless signal transmission.
The main control chip uses the same BES BES2500ZP bluetooth audio SoC as Xiaomi Buds 3 Pro. Supports active noise cancelling (including feed-forward noise cancelling, feedback noise cancelling, hybrid noise cancelling, adaptive noise cancelling, AI voice noise cancelling), and supports 3-MIC to realize high-definition call noise cancelling. The chip also has powerful radio frequency performance, and the average power consumption is less than 5mA, which can realize long battery life or small volume earphone design.
The entire BES2500 series supports Bluetooth V5.2, the built-in MCU has a main frequency of up to 300MHz, and supports LE Audio-LC3 technology, which can provide higher sound quality at the same rate.
According to 52audio, the BES2500 series has been used in many products of Xiaomi, Samsung, OPPO, Honor and other brands. BES’ bluetooth audio solution has been widely adopted by Samsung, Xiaomi, OPPO, JBL, 1MORE, Honor, Baidu, OnePlus and other brands of true wireless headphones.
The crystal oscillator that provides the clock for the bluetooth chip.
Silkscreen Du’s IC.
Silkscreen 0aY IC.
Silkscreen HgC IC.
The microphone pickup hole on the main board is provided with a sponge cover and a large amount of glue to improve the radio performance.
Two metal connectors at the end of the motherboard for charging the earphone.
All components of Xiaomi Buds 3 true wireless noise cancelling earbuds.
In appearance, the Xiaomi Buds 3 true wireless noise cancelling earbuds adopts a cobblestone-shaped oval design for the charging case, which is treated with piano paint, and the body feels smooth and round. The earphones feature a handle-shaped in-ear design that resembles a musical note. The headphone handle is flat, and the back continues the Pro’s bright decorative band design. The lines are smooth and beautiful, which greatly improves the product texture and has a high degree of recognition.
In terms of internal structure configuration, the charging case assembly is fixed on the plastic bracket, and the battery is fixed in the abdomen of the bracket, which plays a good protective role. Built-in Liwinon 480mAh high-voltage battery, equipped with XySemi XB5152J2SZR lithium battery protection IC with reverse load connection, supports wired and wireless input power. The cable adopts Type-C interface and SinhMicro SS881E POWER MCU, which integrates battery charging management and MCU to realize functions such as power management and charging case control.
The wireless charging reception adopts COPO CP2022 wireless charging transmission chip, the maximum power can reach 3W, and it supports Qi V1.2.4 standard. LPS LP6261A 1uA low-power boost chip, boost to charge headphones. Prisemi P14C1N overvoltage and overcurrent protection IC, etc.
The earbuds use a 10mm ultra-dynamic dual-magnetic unit and an independent sound cavity structure to avoid electromagnetic interference. The built-in soft-pack button battery has a capacity of 38mAh, and is also equipped with an XySemi lithium battery protection IC. On the main board, the main control chip is BES BES2500ZP bluetooth audio SoC, which supports active noise cancelling, 3-MIC noise cancelling, and cooperates with three microphones for feed-forward, feed-back and call to achieve multi-scenario noise cancelling effect. The pressure sensor adopts CHIPSEA CSU18M68 pressure sensor detection IC to realize the control of various functions.