FIIL Key Pro adopts a design that combines in-ear and half-in-ear, and provides two wearing experiences by equipping it with different eartips. Equipped with a 10.1mm wool cone composite diaphragm dynamic driver and supporting Bluetooth 5.4, it provides tri-frequency balanced and highly restored audio effects. It also supports 3+12 preset EQs and 10-level customization system, providing users with a wealth of tuning style choices.
In in-ear mode, it support a full-scene noise cancellation experience, providing five modes: noise cancellation, open, wind, listening and close – the maximum noise cancellation depth can reach 40dB. Supports AI call noise cancellation, which can reduce more than 95% of environmental noise. Dual-device connectivity and low-latency gaming mode are also supported.
We have also teardown th FIIL products including: FIIL Belt, FIIL CC Pro 2, FIIL CC Pro, FIIL Key, FIIL CC, FIIL T1, FIIL DRIIFTER PRO, etc. Let’s take a look at the detailed teardown report of FIIL Key Pro.
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$45 – FIIL Key Pro Review
01/ FIIL Key Pro Charging Case Teardown
Disassemble the charging case shell and take out the internal charging bin structure.
The bottom structure of the charging bin, the main components include the motherboard, power input board and battery. 
Remove the screws and remove all components from the charging bin. There are magnets and indicator light guide pillars at the bottom of the cockpit.
The charging case has a built-in lithium-ion battery, model: XD801435, nominal voltage: 3.7V, capacity: 380mAh 1.406Wh, factory date: June 20, 2023, from ShineCell.
The circuit on the side of the charging case motherboard.
The circuit on the other side of the charging case motherboard.
FPC circuit for charging earbuds.
Pogo Pin connector for charging earbuds.
LED indicator light for feedback on charging status.
Silk screen G60 lithium battery protection IC is used for battery overcharge, overdischarge, overcurrent and other protection functions.
An unmarked MCU microcontroller.
The hall element of silk screen 8891M is used to sense the magnetic field changes when the charging case is turned on/off, and then notify the charging case MCU and the headset to pair or disconnect from the connected device.
LPS LP7810 ultra-high-efficiency charging case power management chip, built-in 30V input voltage-resistant linear charger, I²C programmable – supports programmable charging current up to 930mA. The intelligent discharge voltage management function allows the earphone voltage to follow the charging, improving the conversion efficiency by 20% and reducing the waste of power in the charging case – thus increasing the battery life by more than 20%.
LP7810 is packaged in 3mmx3mm QFN-16 and integrates charging, boost converter, NTC management, LDO, and other multiple protection circuits. It supports two-way communication with the headset, charging parameters can be set through the I²C bus, and an interrupt signal is sent to the MCU when a specific event occurs. In addition, LP7810 integrates two-way earphone charging control and LED driver.
The peripheral power inductor of the power management chip cooperates with the power management chip to charge and discharge the built-in battery.
The power input is to the circuit on one side of the small board.
The power input circuit is on the other side of the small board and is soldered to the wires.
02/ FIIL Key Pro Earbuds Teardown
Disassemble the earbud stem back cover.
The inner structure of the cover is equipped with a bluetooth antenna and a touch detection patch, and is equipped with an indicator light guide column.
The internal structure of the cavity secures the motherboard with buckles.
Take out the motherboard unit.
The internal structure of the earbud stem cavity, the left side is fixedly connected to the FPC of the components in the earbud head (connected to the BTB connector of the motherboard); the right side is equipped with a microphone pickup hole.
The circuit on one side of the earbud motherboard.
The circuit on the other side of the earbud motherboard.
The metal dome connects the bluetooth antenna and touch detection patch.
LED indicator light.
Silk screen 2F touch detection IC.
WINSEMI WSDF2311B lithium battery protection IC. The WSDF2311 series is a highly integrated solution for single-cell Li-ion/Li-polymer rechargeable battery pack protection. Integrated advanced power MOSFET, high-precision voltage detection circuit and delay circuit – with overcharge, over-discharge, over-current, short circuit and other protection functions required by the battery. And the power consumption is very low when working, and it also supports CTL shipping mode setting.
Laser carved JWT 24C9 crystal oscillator is used to provide the clock.
Laser-engraved SK5G 321S MEMS microphone is used for voice call function pickup.
Connect to the BTB connector of the FPC.
Bluetrum BT8952F bluetooth audio SoC belongs to the BT895x series and is based on 22nm advanced low-power technology. Supports Bluetooth 5.4 LE Audio protocol and LC3 codec.
Bluetrum BT8952F has a built-in 32-bit high-performance RISC-V processor core and HIFI 4 DSP. The maximum processor speed is 125MHz and the HIFI 4 maximum speed is 270Mhz. Built-in 16Mbits flash memory, 892KB RAM, flexible GPIO pins with programmable pull-up and pull-down resistors. Support GPIO wake-up or interrupt.
BT8952F has built-in 24bit dual-channel DAC (signal-to-noise ratio 106dB, supports single-ended and differential modes) and 24-bit mono ADC (signal-to-noise ratio 103dB, supports single-ended and differential modes). Supports flexible audio equalizer adjustment and 2-way MIC amplifier input. BT8952F has a built-in Sound+ model dual-mic AI call noise cancellation algorithm, which can realize dual-mic beamforming call noise cancellation, or 1+1 microphone call noise cancellation. Supports feedforward and hybrid active noise cancellation functions. Integrated touch control and PMU module.
The peripheral power inductor of the main control chip supplies power to the internal circuit.
The metal connector that connects the charging case to charge the earbud has a rubber seal at the bottom.
Disassemble the earbud head cavity. An isolation layer is provided inside the rear cavity.
Internal structure of the front cavity.
Take out the battery and speaker inside the front cavity, and set up a noise cancellation microphone at the end of the FPC.
On the front of the speaker, the diaphragm is protected by a metal cover and uses a wool basin composite diaphragm.
The back of the speaker is welded to FPC, has a tuning hole, and is protected by a wire mesh.
After actual measurement, the speaker diameter is about 10mm.
The MEMS microphone of the Laser Engraving SKC2 249S is a noise cancellation microphone, used to pick up noise.
The built-in lithium-ion battery model of the headset is: XD 500909, nominal voltage: 3.7V, rated capacity: 35mAh 0.13Wh, from ShineCell.
All components of FIIL Key Pro true wireless noise cancellation earphones.
03/ Summary
FIIL Key Pro once again brings a very unique design – the charging case is small and lightweight, with a baking paint process and excellent texture. At the same time, the case cover is designed with a transparent round window, so you can see the charging bin and earbuds inside. The earbud weighs only 4.2g and is available in in-ear and semi-in-ear modes.
The charging case has a built-in 380mAh lithium battery and uses the LPS LP7810 ultra-high-efficiency charging case power management chip – integrated charging, boost converter, NTC management, LDO, two-way communication with earphones, LED driver, etc. Built-in linear charger with 30V input voltage and supports programmable charging current up to 930mA. Supports earphone voltage follow-up charging, increasing conversion efficiency by 20%.
The earbud is equipped with a 10.1mm wool cone composite diaphragm dynamic driver and two MEMS microphones. Built-in 35mAh soft pack battery, equipped with WINSEMI WSDF2311B lithium battery protection IC. The main control chip is Bluetrum BT8952F bluetooth audio SoC, which supports Bluetooth 5.4. Built-in 32-bit high-performance RISC-V processor core and HIFI 4 DSP. Built-in Sound+ call algorithm, integrated touch detection, PMU function, etc.
PS: Translated from 52audio
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