With the rapid popularity of ANC headphones, OnePlus finally launched the first TWS noise-canceling earphone product OnePlus Buds Pro in 2021, and subsequently launched an iterative upgrade product——OnePlus Buds Z2. It also supports active noise reduction and has been fully upgraded in other functional configurations.

The appearance of OnePlus Buds Z2 true wireless earphones continues the design language of the previous generation, with many adjustments only in the details. The charging case uses a clamshell design similar to a “capsule”. The earphone is a handle-shaped in-ear design. The back touch area is still the classic CD texture. The microphone opening has been adjusted to better reduce the impact of wind noise.

The 11mm dynamic driver is used in the functional configuration, which supports Dolby Atmos. Support active noise cancelling function, with three modes of strong noise cancelling, weak noise cancelling, and transparency, with a maximum noise cancelling depth of 40dB. Built-in 3 microphones cooperate with AI algorithm and physical anti-wind noise design to provide clear voice call effect. It also supports functions such as wearing detection, eartips fit detection, and searching for headphones, and has a comprehensive battery life of 38 hours.

52audio has also teardown before: OnePlus Buds Pro, OnePlus Buds Z, OnePlus Buds, OnePlus Bullets 2, OnePlus Bullets Z and OnePlus Bullets 2T Type-C earphones, etc. Let’s take a look at the appearance design and internal structure configuration of this product.

|1. OnePlus Buds Z2 charging case teardown

After unpacking, we learned about the appearance design of this product and roughly understood the internal layout based on the location of the openings. Now enter the teardown part to see the internal structure configuration information.

Pry open the charging case cover, take out the cockpit, the internal structure of the cavity, and the main components are fixed on the bottom of the charging case.

The bottom structure of the cockpit is equipped with 7 magnets for absorbing the charging case cover and earphones.

The charging internal structure, the upper layer is provided with a bracket to fix the battery.

Take out the battery, the internal structure of the cavity, and the motherboard is fixed under the bracket.

Take out the main components in the charging case.

The charging case indicator light guide column.

Function button cushion rubber pad.

The charging case covers the shaft structure.

There are BIS and CE certifications on the front label of the battery.

There is battery information on the back. Rechargeable lithium ion battery model: 892126, rated capacity: 520mAh/1.976Wh, typical capacity: 525mAh/1.995Wh, charging limit voltage: 3.8V, manufacturer: Chongqing VDL Electronics Co., Ltd..

The silk-screen information on the battery cell is consistent with the external label.

The positive and negative welding points of the battery and the lead, and the protection circuit is located on the main board.

On the side of the motherboard, all ICs are reinforced with glue, and the motherboard is connected with an FPC cable through the ZIF connector.

Circuit on the other side of the motherboard.

ZIF connector, the female seat is fixed with glue.

The Hall element of AP1h1 silk-printed on the head of the cable can notify the charging case MCU and the headset to pair or disconnect with the connected device by sensing the change of the magnetic field.

Two LED indicators of different colors.

Cmsemicon CMS8S5889 MCU single-chip microcomputer, used for charging case control. With a maximum of 32KB program area, 256B RAM space, 2KB XRAM, 1KB non-volatile data area. It supports three working modes: normal, idle, and sleep, which can effectively reduce power consumption. With 1 I2C, 1 SPI, and 2 UART communication modules, it can realize data transmission between the system and other devices. It has a high-precision 12-bit ADC and an internal reference voltage can be selected.

The IC of silk screen FEAS.

TPS SY8801 TWS headset charging compartment SOC, specially designed for TWS headset charging compartment, based on the design to ensure safe and high reliability (support 28V input withstand voltage, built-in full-featured charging and discharging overvoltage, overcurrent, overtemperature, and short circuit Protection and other functions), I2C communication function and internal communication isolation function are also integrated. Through the I2C interface, the MCU of the system can read and configure the internal functions of the power supply and the parameters of battery charging and discharging management, and easily realize such as NTC protection, segmented adjustment of battery current, TWS earphone storage, storage detection, and automatic power output. And other functions.

The internal communication isolation module integrated in TPS SY8801 greatly optimizes the functional design of the intelligent TWS charging compartment, without complicated peripheral circuits, and the MCU can be realized by connecting and controlling the SY8801. Not only can it realize the function of charging the earphones, but also the data communication transmission can be carried out through the power source POGO PIN connected with the earphones, which includes functions such as uploading the power of the charging compartment, clearing the pairing of the earphones in the charging compartment, restoring factory settings, and upgrading the earphone software.

According to 52audio, TPS’s power management chips have been adopted by well-known domestic and foreign brands such as Xiaomi, OPPO, OnePlus, realme, Transsion, MEIZU, 1MORE, Baidu, Edifier, JBL, Harman, Lenovo, etc.

iCM CM1112-WAE lithium battery protection IC. The CM1112 series two-in-one protection chip is specially designed for the TWS headset charging compartment battery. It has a built-in high-precision voltage detection circuit and a delay circuit. By detecting the voltage and current of the battery, it can protect the battery from overcharge, overdischarge, and overcurrent. .

iCM CM1112 series products are ultra-small and ultra-thin DFN2.2*2.9*0.5mm package, which can achieve ultra-low 1.5uA static working power consumption and 10nA sleep power consumption, and integrate discrete NMOS with built-in ESD protection, which is very suitable for applications Lithium battery protection for TWS headset charging compartments, smart watches and other wearable devices.

According to 52audio, there are already true wireless headsets such as OnePlus Buds Pro, OnePlus Buds Z, OnePlus Buds, OPPO Enco W31, Anker Soundcore R100, Skullcandy Sesh, etc., using iCM lithium battery protection IC.

Silk-screen EUZ IC.

TPS SY8702 low-side overvoltage protection (OVP) IC, in SOT23-6 package, with integrated 28m ohm switch NMOS. The low-side switch topology is adopted, and the extremely low on-resistance effectively reduces the input voltage drop. The external setting of the protection voltage makes the application more flexible and provides the simplest and most practical low-cost OVP solution.

MOS tube of silk screen NP6822.

The Type-C charging interface female seat is provided with a rubber sleeve for insulation filling.

The bluetooth pairing function button on the motherboard.

The pogo pin connector for charging the earphone is provided with a cushion.

|2. OnePlus Buds Z2 earphones teardown

Pry open the cavity along the earphone clamping line, and there is a cable connection between the front and rear cavities.

The internal structure of the earphone, the front cavity is provided with a metal cover plate, and the internal components of the front cavity are connected to the main board with the back cavity through the BTB connector.

Pry open the metal cover, the internal structure of the front cavity, and the speaker is fixed on the transparent frame.

Take out the speaker unit, the internal structure of the front cavity, the whole is covered by a black FPC cable.

Internal components of the front cavity.

In the internal structure of the front cavity, the inside of the pressure relief hole is also provided with a fine dust-proof net.

The front of the speaker.

There are tuning holes around the back of the speaker.

After actual measurement, the speaker size is about 11mm.

The speaker has a transparent plastic bracket with a tuning hole in the middle, which is connected to the shell tuning hole and protected by a dust-proof net.

Laser carving R125 ADMF’s inward-facing MEMS microphone is used to pick up the internal noise of the ear canal.

Metal contacts for charging the earphone.

Teardown the rear cavity position, lift up the main board, and connect the lower battery unit to the main board through a wire.

Take out the battery and the main board, and a sponge pad is provided at the bottom of the back cavity.

Battery and motherboard circuit.

The earphone uses a soft-pack button battery, model: 1063, voltage: 3.80V, capacity: 40mAh/0.152Wh, also from VDL.

BES BES2500Z ultra-low power bluetooth audio SoC supports the latest bluetooth 5.2 standard. Ultra-low system power consumption effectively improves the single battery life of the headset. The BES2500 series is a dual-core digital bluetooth noise cancelling chip with different suffixes and different configurations, which are customized by the manufacturer.

According to 52audio, the current BES2500 series has been used by brands such as Xiaomi, Samsung, OPPO, Honor and many other products. BES bluetooth audio solutions have been widely adopted by true wireless headsets from brands such as Samsung, Xiaomi, OPPO, JBL, 1MORE, Honor, Baidu, OnePlus, and Transsion.

The 26.000MHZ crystal oscillator provides the clock for the bluetooth chip.

Scientic SDHL1608F4R7MT fully magnetically shielded precision winding inductor, with the built-in step-down circuit of the bluetooth chip to supply power to the bluetooth main control chip.

SDHL series precision wire wound inductors adopt a fully magnetic shielding structure, which reduces radiation and interference to the surroundings, and can optimize the noise and pop sound of TWS earphones. The copper wire is wrapped. Under special circumstances, when inductive howling occurs, the wrapping layer can suppress the vibration of the copper wire, thereby optimizing the inductive howling phenomenon.

The shielding layer of SDHL series precision wire-wound inductors is made of materials with enhanced magnetic permeability, which enhances the performance of the inductor, and at the same time tightens the magnetic line of force, so that the bottom of the inductor can be routed. The bottom copper wire is not exposed, which can avoid high-temperature solder paste sputtering during the production process, thereby improving the quality control of mass products.

Magnetic glue power inductors.

Another precision wire wound inductor.

Bluetooth coaxial antenna female base.

Two BTB connectors, used to connect the front cavity and the internal components of the earphone handle.

TPS SY5500 bluetooth headset charging and communication solution. SY5500 is a chip specially designed for TWS earphones, providing a perfect solution for charging and isolating communication. The chip integrates linear charging management, discharge protection, (charging case and headphones) single-wire two-way data communication and I2C communication interface, which is convenient for users to realize headset charging and discharging management and protocol communication.

The iCM CM1123-WAC lithium battery protection IC has a built-in high-precision voltage detection circuit and a delay circuit. By detecting the voltage and current of the battery, it can protect the battery from overcharge, overdischarge, and overcurrent. It is suitable for the protection circuit of single-cell lithium ion/lithium polymer rechargeable batteries.

Remove the earplugs at the bottom of the earphone handle, you can see the internal microphone structure.

Because the earphone handle adopts an integrated design, and the inside is fixed by a lot of glue, the cavity can only be violently cut, and an FPC cable and coaxial feeder are set inside the cavity, which are fixed on the cylindrical frame.

Take out the internal components of the earphone handle, and the structure on one side of the component.

On the other side of the component, the two ends of the frame are the acoustic structure of noise cancelling microphone and pickup microphone.

The internal components of the earphone handle are teardown.

BTB connector male socket connected to the motherboard.

Bluetooth coaxial antenna plug.

Laser carving R125 ADMF’s MEMSnoise cancelling microphone is used to pick up external environmental noise.

Silkscreen AR1e IC.

It is also the MEMS microphone of the laser carving R125 ADMF, which is used for voice call pickup.

Bluetooth antenna for earphone.

All components of OnePlus Buds Z2 true wireless earphones.

|3. Summary

OnePlus Buds Z2 true wireless earphones continue the design of OnePlus Buds Z in appearance. The charging case resembling a “capsule” is small in size, thick in texture, and smooth to the touch. The handle-shaped in-ear headphones use the classic CD texture to enhance the product’s texture. The 4.5g lightweight body, matched with three different sizes of silicone eartips, provides a comfortable wearing effect.

In terms of internal circuits, the charging case is similar to the previous generation. The built-in battery capacity has been increased to 525mAh, and the iCM CM1112-WAE lithium battery protection IC is protected against overcharge, overdischarge, and overcurrent. The built-in battery is charged by TPS SY8801 TWS headset charging compartment SOC, which supports 28V input withstand voltage, built-in full-featured charging and discharging overvoltage, overcurrent, overtemperature, short circuit protection and other functions, and integrated I2C communication function and internal communication isolation function . TPS SY8702 low-side overvoltage protection IC, Cmsemicon CMS8S5889 MCU microcontroller, etc.

Due to the increase in functions, the headset adopts a brand-new design, which is more complicated than the previous generation. The inside of the earphone mainly includes the FPC cable that connects the speaker and microphone of the front cavity. The FPC cable of the main board, battery, earphone handle in series with microphone, bluetooth antenna and other components in the back cavity are connected through the BTB connector. The front cavity is also isolated by a metal cover plate.

In terms of configuration, it uses an 11mm dynamic driver and a 40mAh soft-pack button battery. The iCM CM1123-WAC lithium battery protection IC is responsible for overcharge, overdischarge, and overcurrent protection. BES BES2500Z ultra-low power bluetooth audio SoC, supports bluetooth 5.2, integrates active noise cancelling function, and is equipped with Scientific SDHL1608F4R7MT full magnetic shielding precision winding inductor for power supply. The TPS SY5500 bluetooth headphone charging and communication solution provides charging and discharging management and data communication for OnePlus Buds Z2 earphones.

Source: 52audio

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