Related Reading: FIIL Key Earbuds Review: Balanced performance all round
FIIL Key is a new generation of FIIL products. In terms of appearance, the German DA design studio is invited to design, the earbuds are light and provide a comfortable and non-sensing wearing experience. In terms of functional configuration, it is equipped with a 13mm custom titanium-plated diaphragm unit, upgraded Bluetooth 5.3 chip, and supports a wide sound range of 15Hz-22kHz. Support dual-mic intelligent call noise cancellation and dual device connection, with 24 hours of comprehensive battery life.
01/ FIIL Key charging case teardown
Next, enter the teardown section to see the internal structure configuration information.
Pry open the charging case shell, the internal structure of the cavity. The back cover holds the battery unit, which is connected to the motherboard on the cockpit by wires.
The cockpit is also provided with a small power input board, which is also connected to the main board through wires.
Remove the battery, the inner structure of the rear cover of the charging case.
FIIL Key charging case teardown.
The inner structure of the cockpit is provided with magnets and indicator light guide columns.
The main circuit inside the charging case.
The battery is equipped with a circuit protection board, above which there is an integrated lithium battery protection IC with silkscreen G60 and a thermistor that detects the battery temperature.
The power supply is input to the circuit on one side of the small board, and the Type-C charging base is welded to the bottom plate to reduce the thickness of the small board.
The circuit on the other side of the power input board.
The circuit on one side of the charging case motherboard.
The circuit on the other side of the charging case motherboard.
The LPS LP6261 ultra-low quiescent current synchronous boost converter is used to boost the built-in battery in the charging case to charge the earbud.
The LP6261 has a TRUE true shutdown function, which can disconnect the input and output under shutdown and output short-circuit conditions, and the 1.2MHZ switching frequency can use small volume inductors and capacitors. The switch pin adopts a high-voltage 9V process, which can effectively absorb the high-voltage peak of the production capacity when the earphone is unplugged and plugged. At the same time, LP6261 has no whistling sound in the range of full load capacity (especially light load).
The LP6261 consumes only 1UA of quiescent current under light load conditions and can achieve up to 75% efficiency under 20uA load. The conversion efficiency from 3.3V to 5V is as high as 93% under 200mA load.
According to 52audio, there are audio products from Black Shark, Xiaomi, Honor, OPPO, Huawei, Redmi, realme, Lenovo, Sony, Nokia, Motorola, Edifier, Soundcore, 1MORE, QCY, UGREEN, Razer and many other brands. The product adopts LPS power management chip.
The boost inductor that works with the boost chip to charge the earphones.
The Pogo pin connector on the motherboard for charging the earbud.
SinhMicro SS809 is an AD-type microcontroller with integrated charge and discharge management. It has a built-in linear charging unit to charge lithium batteries. At the same time, there is a special earphone communication interface to realize the two-way communication function between the charging case and the earphone. SS809 integrates MCU microprocessor and embedded flash memory, which can easily upgrade its firmware and facilitate engineers to add personalized customization functions. Especially in terms of power display, in addition to controlling the display of 1-5 lights, it also supports RGB lighting effects, LED 188 digital tubes, custom patterns, etc., providing engineers with free programming space.
In response to the intelligent trend of TWS earbuds, the SS881X series has achieved two-way communication with major mainstream earbud platforms, and the products can be quickly iterated. Moreover, the chip integrates a special interface to support USB whole machine upgrade and production testing.
According to 52audio, there are Xiaomi, OPPO, Honor, Redmi, realme, Nubia, Lenovo, Nokia, HTC, Edifier, Soundcore, 1MORE, FIIL, 233621, JBL, Philips, Skullcandy, Razer, ZMI, etc. Many brands of TWS earphones have adopted the SinhMicro solution.
The hall element of the silk screen qH1t is used to sense the magnetic field change when the charging case opens and closes the cover, and realizes the function of opening the cover and connecting it.
Weimob S2UF IC.
02/ FIIL Key earbuds teardown
Proceed to the earbud teardown section. Pry open the cavity along the parting line, and a black insulating paper is provided between the front and rear cavities for protection.
The speaker structure inside the front cavity is fixed by blue glue.
The speaker and battery are respectively connected to the main board of the rear cavity by wires, and the wires are sealed by glue.
Pry off the back cover of the headphone stem to reveal the internal structure of the cavity.
The inner side of the cover is provided with a bluetooth antenna and a touch detection patch, and the exposed copper is connected to the motherboard. Both sides are provided with a microphone pickup sealing structure.
Microphone groove, internal fine dust net protection.
FIIL Key true wireless earphones teardown.
The internal structure of the front cavity, the tuning hole is protected by a fine dust-proof net.
Take out the main board, the internal structure of the headphone stem cavity.
Magnet for earbud attachment.
The front of the speaker is custom-plated with titanium diaphragm.
Tuning holes are set around the back of the speaker to improve acoustic performance.
After actual measurement, the speaker size is about 13mm.
The earbud uses a soft-pack button battery, model: 1040PF3, voltage: 3.8V, capacity: 0.114Wh.
The other side of the battery is screen-printed with a QR code, and the wires are welded to the positive and negative electrodes.
The circuit on one side of the earbud motherboard, and the left and right earbuds are distinguished by blue and green.
The circuit on the other side of the earbud motherboard.
AIROHA AB1562U bluetooth audio SoC, supports Bluetooth 5.3. The AB1562 family of single-chip solutions are optimized for TWS and stereo headphones, delivering excellent audio performance, clear voice and premium music quality in most bluetooth audio headphone applications.
AB1562 has built-in Tensilica HiFi Mini processor for I/O peripheral control, protocol stack and DSP processing functions of AB1562/1561. Support a new generation of echo cancellation and noise cancellation solutions to improve the audio quality of headphone voice calls. Supports Airoha MCSync technology, allowing seamless switching between left and right earbuds for a more balanced sound and low latency.
According to 52audio, many bluetooth headphones from Sony, Zepp Health Corporation (Huami), 1MORE, realme, FIIL, Edifier and other brands on the market have adopted the AIROHA solution.
The crystal oscillator that provides the clock for the bluetooth chip.
The MEMS microphone of the laser carving MD19 R115 is used for the pickup function of voice calls, from RAYKING.
Another MEMS call noise cancellation microphone of the same specification. The two microphones work together to pick up the sound, together with the noise cancellation algorithm, to provide a clear voice call effect.
Silkscreen 33D01 lithium battery protection IC.
The metal connector for charging on the earbud’s motherboard is provided with a rubber pad buffer seal.
Metal dome connector for connecting touch detection patches.
Metal shrapnel for connecting the bluetooth antenna.
All components of FIIL Key true wireless bluetooth earbuds.
FIIL Key continues the family-style metal-like texture in the design. The charging case is designed with a square button similar to launchpad, with CD textured FIIL brand decoration, which is very beautiful and recognizable. The earbuds use a handle-shaped semi-in-ear design and weigh only 3.7g, providing a comfortable and non-sensing wearing experience.
In terms of internal structure and configuration, the charging case uses the Type-C interface to input power, and the SinhMicro SS809 microcontroller is responsible for charging the built-in 420mAh lithium battery. At the same time, there is a special headset communication interface to realize the two-way communication function between charging case and earbuds. The built-in battery is boosted to charge earbuds by the LPS LP6261 ultra-low static current synchronous boost converter, with a TRUE shutdown function that disconnects the input and output during shutdown and output short-circuit conditions.
The earbud uses a 13mm custom titanium-plated diaphragm unit and a 0.114Wh soft pack button test battery, which are connected to the motherboard through wires. On the motherboard, the main control chip is AIROHA AB1562U bluetooth audio SoC, which supports Bluetooth 5.3, Airoha MCSync technology, a new generation of echo cancellation and noise cancellation solutions. Equipped with two RAYKING MEMS microphones to improve the quality of voice calls.
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