OnePlus‘ product update in the TWS earbuds market is not very fast. At present, its products on sale include the flagship OnePlus Buds Pro and the mid-range OnePlus Buds Z2, two true wireless noise cancellation headphones. Recently, OnePlus launched the OnePlus Buds N (OnePlus Nord Buds) true wireless earbuds, which is an entry-level product positioned at the mid-to-low end to complement the product line and meet market demand.
OnePlus Nord Buds (ONEPLUS Buds N) adopts a new and refined trend design, equipped with 12.4mm dynamic driver, titanium-plated composite diaphragm, and Dirac Audio Tuner technology blessing, providing clear and transparent sound quality. The presets have a variety of different styles of sound effects and support Dolby Atmos. Support dual-microphone AI call noise cancellation, with anti-wind noise design, provide clear call effect. It has IP55 dustproof and waterproof, 30 hours of comprehensive battery life and 94ms low latency performance.
52audio has also teardown OnePlus Buds Pro, OnePlus Buds Z2, OnePlus Buds Z, OnePlus Buds true wireless earphones, etc. Let’s take a look at the appearance design and internal structure configuration of this product.
01/ OnePlus Nord Buds charging case teardown
Enter the teardown section below to see the internal structure configuration information.
Pry open the charging case and take out the cockpit structure.
The bottom structure of the cockpit is equipped with 5 magnets, which are fixed with red glue to absorb the charging case cover and earbuds.
The internal structure of the cavity, the main board is located at the bottom of the charging case, and the battery unit is arranged on the side.
Take out the battery, the internal structure of the cavity, and the motherboard are fixed by two screws.
OnePlus Buds N charging case teardown.
The main component circuit in the charging case, the battery is connected to the motherboard by wire welding.
Charging case built-in rechargeable lithium-ion battery Model: 751443, rated capacity: 480mAh 1.77Wh, typical capacity: 490mAh 1.81Wh, nominal voltage: 3.7V, charging limit voltage: 4.35V, manufacturer: Chongqing VDL Electronics Co.,Ltd ..
Tear off the outer insulating plastic skin, and the silkscreen information on the inner cell is consistent with the outer label.
The circuit on one side of the charging case motherboard.
The circuit on the other side of the charging case motherboard.
The Hall element of the silk screen 4002 realizes the opening and connecting function by sensing the magnetic field change of the charging case switch cover.
Screen printing UtG’s voltage regulator IC.
The battery wire solder joints are glued and fixed for protection.
iCM CM1112-WAE lithium battery protection IC. The CM1112 series two-in-one protection chip is specially designed for the TWS earphone charging compartment battery. It has built-in high-precision voltage detection circuit and 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 power consumption and 10nA sleep power consumption. And it integrates discrete NMOS with built-in ESD protection, which is very suitable for lithium battery protection of wearable devices such as TWS earphone charging compartment and smart watch.
According to 52audio, in the field of personal audio, iCM lithium battery protection IC has been adopted by many TWS earbuds under brands such as OPPO, OnePlus, Soundcore, AUKEY, and Skullcandy.
TPS SY8801 TWS earphone charging box SOC, specially designed for TWS earphone charging box. On the basis of the design to ensure safety and high reliability (supports 28V input withstand voltage, built-in full-function charging and discharging overvoltage, overcurrent, overtemperature, short circuit protection, etc.), it also integrates I2C communication function and internal communication isolation function . 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 charge and discharge management, and easily realize such as NTC protection, segmental adjustment of battery current, TWS earphones in and out of the warehouse, and the power output is automatically turned on. and other functions.
The integrated internal communication isolation module of TPS SY8801 greatly optimizes the functional design of the smart TWS charging compartment. No complicated peripheral circuits are required, and the MCU can be realized by connecting and controlling the SY8801. It can not only realize the function of charging the earbuds, but also transmit data through the POGO PIN of the power supply connected to the earbuds, realizing functions including uploading the power of the charging compartment, clearing and pairing the earbuds in the charging compartment, restoring factory settings, and upgrading software.
According to 52audio, the TPS power management chip has been adopted by Baseus, Xiaomi, OPPO, OnePlus, realme, 1MORE, Baidu, Edifier, JBL, HARMAN, Lenovo and other brands.
Screen-printed 23P TVS for input overvoltage protection.
Cmemicon CMS8S5889 MCU microcontroller for charging case control. Has a maximum 32KB program area, 256B RAM space, 2KB XRAM, 1KB non-volatile data area. It supports three working modes of normal, idle and sleep, which can effectively reduce power consumption. It has 1 channel I2C, 1 channel SPI, 2 channel UART communication modules, which can realize data transmission between the system and other devices. With high precision 12-bit ADC and selectable internal reference voltage.
Silkscreen “02AJF” TPS SY8702 low-side overvoltage protection (OVP) IC. It adopts SOT23-6 package, integrates 28mΩ switch NMOS inside, adopts low-voltage side switching topology, extremely low on-resistance effectively reduces input voltage drop, and the external setting of protection voltage makes the application more flexible, providing the simplest and most practical low-cost OVP solution Program.
Two LED indicators with different colors on the main board are used to feedback the working status of the charging case.
Type-C charging socket, engraved model “L22114”.
Charging case function button.
The two Pogo Pin connectors for charging the earphones are protected by a sponge pad at the bottom, which plays a role of sealing and waterproofing.
02/ OnePlus Nord Buds earbuds teardown
Enter the earbud teardown section and pry open the headphone cavity along the parting line.
Remove the motherboard from the back cover of the headphone stem.
The inner side of the cover is provided with a bluetooth antenna and capacitive touch detection, and the exposed copper is connected to the motherboard.
The microphone pickup holes at both ends are provided with a sealed acoustic structure to improve the sound collection performance.
Open the motherboard and connect the lower cable to the components in the headphone head.
Take out the motherboard and the battery from the cavity, connect the ends of the FPC cable to the battery and the speaker unit respectively, and the battery is fixed on the plastic cover, which also acts as an isolation from the speaker.
Take out the speakers, OnePlus Buds N earbuds teardown.
The internal structure of the front cavity.
Pressure relief hole and two metal connectors for charging earbud.
The plastic part that holds the battery in place.
The earbud has a built-in soft-pack button battery, and the QR code is screen-printed on the battery.
The positive and negative welding points of the battery and the cable.
There is battery parameter information on the battery label, model: 1058PF3, rated voltage: 3.80V, rated capacity: 41mAh/0.155Wh, also from VDL.
On the front of the earbud speaker, a titanium-plated composite diaphragm is used. During the disassembly process, to pry up the unit, the edges are deformed.
On the back of the speaker, the positive and negative electrodes are welded to the cable.
The circuit on one side of the earbud motherboard is affixed with a silk-screened QR code label.
Circuit on the other side of the motherboard.
The solder joints between the cable and the motherboard are glued for protection.
Three metal shrapnel on the motherboard for connecting the bluetooth antenna and the touch sensor.
Laser engraving MD51 D184 MEMS microphone, which is used to pick up sound with noise cancellation function.
According to 52audio, this product is from MEMSensing, model MSM421ACT006, size 2.75mm × 1.85 mm × 0.95mm, is an omnidirectional top opening microphone. With high performance and high reliability, and compatible with SMT, does not reduce sensitivity.
The same type of call pickup microphone on the other end of the main board, together with the noise cancellation microphone, forms a beamforming array, which is used for the noise cancellation function of the call and provides a clear voice call effect.
Screen printing 31BP’s touch detection IC.
TPS SY5501 is a chip specially designed for TWS earbuds, providing a perfect solution for charging and isolated communication. The chip integrates linear charging management, discharge protection, (charging case and earbuds) single-wire two-way data communication and I2C communication interface, which is convenient for users to realize earbud charging and discharging management and protocol communication. The maximum charging current of SY5501 is adjustable by external resistance, and it supports constant current charging ICC and floating charging voltage VFLOAT gear I2C adjustment. The chip integrates NTC detection and protection functions to more safely manage battery charge and discharge.
SY5501 has battery discharge protection and ship mode function, which can realize the low power consumption of earbud system. The chip integrates private control commands, and the charging bin can send commands through VIN to control the SY5501 to realize the on-off and reset operations of the earbuds master. SY5501 also supports intelligent identification of in-warehouse/out-of-warehouse status, and actively informs the earbuds master. SY5501 is feature-rich and low power consumption, shortening the development cycle of bluetooth headphones. The compact QFN14-1.6mmx1.6mm package saves a lot of space for the bluetooth earphones solution.
TPS SY5501 frame diagram.
iCM CM1126B-WAC 2-in-1 single-cell battery protection IC with shipping mode, built-in high-precision voltage detection circuit and delay circuit. By detecting the voltage and current of the battery, it can protect the battery from overcharge, overdischarge, and overcurrent, and is suitable for the protection circuit of single-cell lithium-ion/lithium polymer rechargeable batteries. With a shipping mode, the small-capacity battery pack can meet the needs of sea transportation and long-term storage.
BES BES2500IU bluetooth audio SoC, BES2500 series is Hengxuan’s new generation of bluetooth audio SoC, different suffixes have different configurations and functions. BES BES2500IUC/IU/IZ series, supports Bluetooth 5.2, ultra-low noise floor, 512K SRAM, 2M/4M FLASH, it is a cost-effective solution.
According to 52audio, the BES2500 series has been adopted by 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 earphones.
The crystal oscillator that provides the clock for the bluetooth chip.
The precision winding inductance on the periphery of the main control chip supplies power to the internal circuit of the chip.
OnePlus Buds N true wireless earbuds all components.
The OnePlus Buds N true wireless earbuds adopt a completely new design that is completely different from the Buds Z series in appearance. The charging case is designed as an oval cylinder with smooth piano paint process, which has a good texture performance. The earbuds use a handle-shaped in-ear design, the headphone stem corresponds to the appearance of the charging case, and the touch area is decorated with bright silver decorative pieces, which effectively improves the product texture and recognition.
In terms of internal structure and configuration, the charging case has a built-in VDL 480mAh rechargeable lithium battery, and the battery wires are connected to the motherboard by welding. The iCM CM1112-WAE lithium battery protection IC is set on the motherboard. The motherboard is equipped with TPS SY8801 TWS charging bin SOC, supports 28V input withstand voltage, built-in full-function charging and discharging overvoltage, overcurrent, overtemperature, short circuit protection and other functions, and integrates I2C communication function and internal communication isolation function. It adopts Cmemicon CMS8S5889 MCU microcontroller, TPS SY8702 input overvoltage protection IC, etc.
The internal acoustic device of the earbud is equipped with a 12.4mm titanium-plated dynamic driver, and two MEMSensing MEMS microphones are used to pick up the sound with the noise cancellation function. Built-in VDL 41mAh soft pack button battery, equipped with ICM CM1126B-WAC lithium battery protection IC, and also has a shipping mode, so that the small-capacity battery pack can meet the needs of sea transportation and long-term storage. It adopts TPS SY5501 power management chip for charge and discharge management, and integrates single-wire two-way data communication and I2C communication interface. The main control chip is BES BES2500IU, which supports Bluetooth 5.2, ultra-low noise floor, 512K SRAM, 2M/4M FLASH, which is a cost-effective solution.
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