Following the AirDots series of products, Redmi launched the Buds series of TWS headsets this year. The first product – Redmi Buds 3 true wireless earphones, broke through the original appearance and adopted a new design. Recently, Redmi launched the Redmi Buds 3 Life (Redmi Buds 3 Youth Edition), which adopts a new design style compared to the standard version.

The charging case has an oval shape similar to “pebbles”, with a small volume, round and no edges. The earphone is a bean-shaped in-ear design, but the overall design is very different from the AirDots series. It is equipped with soft silicone “cat ears” to provide a more comfortable and stable wearing effect.

In the functional configuration, the Bluetooth 5.2 chip is used to support the call noise cancellation function and provide clear calls. Support the game low latency mode to enhance the game experience. It adopts touch operation, supports multiple control modes, and is convenient to use. It also supports IP54 dust and water resistance, and can be used for daily commuting and fitness exercises; it has a single 5 hours of battery life and an overall 18 hours of battery life.

52audio has teardown Xiaomi’s products including: Xiaomi FlipBuds Pro, Xiaomi Air 2 Pro, Xiaomi Air2 SE, Xiaomi Air 2S, Xiaomi Air 2, Redmi Buds 3, Redmi AirDots 3 Pro, Redmi AirDots 3, Redmi AirDots 2, Redmi AirDots, Xiaomi Xiaoai Play speaker and other 16 products under Xiaomi. Let’s take a look at the internal structure of this product.

01/ Redmi Buds 3 Lite charging case teardown

After unpacking, we learned about the compact and exquisite design of this product. Let’s enter the disassembly part to see the internal structure configuration.

Pry open the charging case cover and take out the headset cockpit.

The indicator light guide column on the shell.

In the cockpit side structure, the upper and lower PCB boards are connected by wires, and the battery unit is fixed in the middle.

The structure on the other side of the cockpit.

The side structure is provided with a card slot fixed with the shell.

The motherboard is fixed to the bottom of the cockpit by screws.

Remove the screws, take off the motherboard, the battery is fixed to the motherboard with double-sided adhesive, there is a small power input board at the bottom of the cockpit.

Remove all the components in the charging case, there are three magnets at the bottom to absorb the charging case cover and earphones.

The front of the main components in the charging case.

The back of the main components in the charging case.

The charging case front circuit of the motherboard.

Charging case on the back of the motherboard.

The TVS with silk-screen T12 003 has an input self-recovery fuse on the right side, which is used for charging case input overvoltage protection.

LPSemi LP4067 lithium battery charging IC is a complete constant current/constant voltage linear charger for single-cell lithium-ion batteries. The input withstand voltage of 30V, the SOT23-6 package and the low number of external components make the LP4067 very suitable for portable applications.

The internal integrated MOSFET does not require external current sampling resistors and blocking diodes. Thermal feedback regulates the charging current to limit the chip temperature under high-power operation or high ambient temperature. The charging voltage is fixed at 4.2V, and the charging current can be externally programmed through a single resistor.

According to 52audio, audio products from brands such as Xiaomi, OPPO, Huawei, Lenovo, Motorola, Realme, Edifier, QCY, JLab, Skullcandy, Boltune and other brands have adopted a large number of LPSemi power management solutions.

LPS LP6261 ultra-low quiescent current synchronous boost converter, with TRUE true shutdown function, can disconnect input and output under shutdown and output short-circuit conditions, 1.2MHz switching frequency can use small inductors and capacitors; switching feet use high voltage 9V The technology can effectively absorb the high-voltage spikes of the production capacity when the earphone is plugged and unplugged; at the same time, the LP6261 has no whistling sound within the full load capacity range (especially when the load is light).

LP6261 consumes only 1uA quiescent current under light load conditions, and can achieve up to 75% efficiency under 20uA load. Under 200mA load, the conversion efficiency from 3.3V to 5V is as high as 93%.

Screen printing CQ0 K2G battery protection IC.

Power input circuit on the front of the small board.

Power input circuit on the back of the small board.

LED indicator.

Pogo Pin connector for charging earphones.

The charging case uses a polymer lithium-ion soft pack battery, model: BW30, rated capacity: 315mAh/1.17Wh, nominal voltage: 3.7V, charging limit voltage: 4.2V, manufacturer: Dongguan LIWINON Energy Technology Co., Ltd., China manufacture.

Notices are printed on the label on the back of the battery.

02/ Redmi Buds 3 Lite earbuds teardown

Enter the disassembly part of the earphone and pry open the cavity along the parting line. A small power input board is arranged inside the front cavity, which is connected to the main board of the back cavity through a wire.

A shielding patch is affixed to the battery inside the rear cavity, with silk screen K79-C1.0.

Uncover the patch and take out the battery.

Take out the main board, and set the touch detection patch and bluetooth antenna at the bottom of the back cavity.

Take out the speaker and power input board inside the front cavity, and the internal structure of the cavity.

The main components inside the earphone, the battery, the speaker and the power input board are respectively connected to the main board through wires.

Battery shielding patch.

The headset uses a soft-pack button battery. The silk-screen information on the label has model number: 1140, rated voltage: 3.8V, and capacity: 36mAh/0.14Wh.

There is a silk-printed QR code on the back of the battery.

The front of the earphone dynamic speaker adopts an external magnetic design.

On the back of the earphone speaker, there is a tuning hole in the middle position, which is covered by a dust-proof net.

After actual measurement, the speaker size is about 5.5mm.

The earphone power input is on the front of the small board, and the magnet is fixed by glue in the middle, which is used to adsorb the charging case.

The back of the power input board.

The front circuit of the headset motherboard.

The side of the back of the motherboard that meets the earphone shell is filled with a support sponge.

The circuit on the back of the motherboard.

A pogo pin connector for connecting a bluetooth antenna.

The touch chip of the silk screen HH01F is used to detect touch operations.

Lithium battery protection IC with silk screen 0f C4.

Laser carving MD32 B123’s MEMS microphone is used for voice call pickup.

The main control chip adopts the BES BES2500IUC. The BES2500 series is Hengxuan’s new generation of bluetooth audio SoC, both of which support bluetooth 5.2, with different suffix configurations and functions. BES BES2500IUC/IU/IZ series, with ultra-low noise floor, 512K SRAM, 2M/4M FLASH, is a cost-effective solution.

According to 52audio, many products under brands such as Honor and OPPO have adopted the BES2500 series. True wireless headsets from brands such as Samsung, Xiaomi, OPPO, JBL, 1MORE, Honor, Baidu, and OnePlus have adopted a large number of BES solutions.

The crystal oscillator that provides the clock for the bluetooth chip.

All components of Redmi Buds 3 Youth Edition true wireless earphones.

03/ Summary

The overall design of the Redmi Buds 3 Lite is small and exquisite. The oval charging case is made of frosted material, which is light and easy to carry. The bean-shaped in-ear headphones are matched with soft silicone eartips and earwings, which are light and comfortable to wear. Equipped with three sizes of eartips and two sizes of earwings, it can meet the needs of different people.

The internal structure configuration is relatively simple, the charging case adopts Type-C interface input power, built-in LIWINON 315mAh lithium-ion soft pack battery, built-in battery is charged by LPSemi LP4067 lithium battery charging IC, and boosted by LPSemi LP6261 synchronous boost converter for earphones The internal battery is charged, and the input has a self-recovery fuse and TVS for overvoltage protection.

The Redmi Buds 3 Lite earphones uses a 5.5mm dynamic speaker unit and a 36mAh soft-pack button battery, which is connected to the motherboard through wires. On the motherboard, the main control chip is BES BES2500IUC, supports bluetooth 5.2, has an ultra-low noise floor, 512K SRAM, 2M/4M FLASH. A single MEMS microphone is used for voice call function pickup.

Source: 52audio

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