Traditional hair dryers feature unattractive designs and limited functions, largely ignoring aesthetics and user experience. Around 2023, given the maturity of high-speed brushless motor technology and the value-added functions of various accessories, the high-speed hair dryer market witnessed explosive growth. As a comprehensive "general store" for small home appliances, Xiaomi launched its high-speed water ion hair dryer, highlighting water ion hair care and an ultra-high-speed motor, which attracted extensive consumer attention. However, for electronic engineers and hardware enthusiasts, the internal circuit design and chip selection are of greater concern. Therefore, in this issue, eefocus will perform a teardown of this product to explore its internal hardware solutions.
There is indeed nothing much to say about the appearance; it is exquisite, compact, and visually appealing. Let's proceed directly to the teardown section.
Teardown
After teardown, the main internal structure and component layout are shown in the figure below, including the hair dryer head with a negative ion generator, the temperature control adjustment board, the power control main board, the high-speed fan, and the power switch for 2-speed adjustment.
- Hair Dryer Air Outlet
Compared with the air outlet of traditional hair dryers, the head of the Xiaomi high-speed water ion hair dryer integrates more functional components.
The brown component in the image above is the negative ion/water ion generator (model XH-203A) from Xianghejin Electronics. Its actual function is that during hair drying, negative ions can neutralize the static electricity generated by hair friction, thereby reducing hair frizz. Mica sheets surround the heating wire for thermal insulation, and there is a bimetallic thermostat for overheat protection on the electric heating wire, which will automatically pop open when the temperature exceeds the limit.
On the other side of the hair dryer head, there is a small LED circuit board for light indication, metal probes led from the negative ion generator to generate a high-voltage electric field and ionize the air to release negative ions, and an NTC thermistor for temperature detection to achieve precise temperature control.
- Motor & Power Switch
As the core of the hair dryer, the Xiaomi high-speed water ion hair dryer adopts a high-speed brushless DC motor from Lianfeng Motor, model LF-1713. The rated voltage is 310V, and the rated power is60W. The rotational speed reaches 110,000 RPM. The top of the motor is equipped with 13 aluminum alloy fan blades; the asymmetrical odd-numbered blades can effectively reduce noise and suppress self-vibration, providing stronger stability.
Interestingly, the motor is marked with a duty cycle (15 min on, 1 min off), which is sufficient for general household use, as 15 minutes is enough to dry the hair.
The hair dryer switch uses a power switch from Tuolin Electronics, model TS-13S, with parameters of 10A/250V~, featuring 2 working positions corresponding to 2-speed adjustment.
- Main Board
Almost all components are laid out on the front side of the PCB main board.
The 220V AC mains input first passes through a primary protection circuit composed of a fuse and a varistor, and then enters the rectification and filtering stage. The GBP410 rectifier bridge is responsible for converting AC to DC, and the rectified high-voltage DC is smoothed and filtered by a 120µF/440V aluminum electrolytic capacitor from Ketuo Electronics.
The main control chip is the LKS32MC038Y6P8B microcontroller from LKS (LINKO Semiconductor). It is a 32-bit MCU based on the Arm Cortex-M0+ core, responsible for receiving input signals from buttons and thermistors, calculating and outputting PWM waves to drive the motor, and monitoring current sampling feedback to achieve closed-loop speed control. In addition, the MCU also handles communication and coordination tasks with the negative ion generator and the heating wire thyristor, ensuring that when the wind speed switches or the heating gear changes, each functional module can transition smoothly, avoiding instantaneous overcurrent or temperature overshoot.
The motor drive uses three LKS1D5005D single-phase intelligent power modules from LKS as the core of the inverter. This model of IPM (Intelligent Power Module) is sufficient to drive the high-speed brushless motor with a rated power of 60W (or hundreds of watts). Compared with the inverter bridge built with discrete components, the advantages of the IPM lie in its small parasitic parameters, fast switching speed, and optimized heat dissipation path, which directly improves the upper limit of the motor's rotational speed and operational stability.
The chips in the power management circuit include the BP85224D step-down conversion PMIC (Power Management IC) from Bright Power Semiconductor and the CJT1117B low-dropout linear regulator from Changjing Technology. The BP85224D is used to step down the high-voltage bus voltage to low-voltage DC, while the CJT1117B further provides a stable 3.3V power supply for digital circuits such as the MCU.
In terms of heating and safety control, a BTB12-600BW thyristor from Hanjingyuan is used to adjust the power of the heating wire.
The back of the main board only has some resistors and capacitors, as well as a JW5173S synchronous step-down converter from Joulwatt.
The main component BOM of the Xiaomi high-speed water ion hair dryer is shown in the table below:
Summary
The teardown reveals that the Xiaomi high-speed water ion hair dryer fully integrates the full-link functions of rectification and filtering, auxiliary power supply, motor drive, heating control, and ion generator within a compact internal space. Its most significant hardware feature lies in the comprehensive domestic substitution of core chips—the power management solution from Bright Power Semiconductor, the MCU and IPM from LKS, the LDO regulator from Changjing Technology, and the optocoupler devices from Lightning Optoelectronics, which together build a stable and efficient domestic ecosystem. It is foreseeable that, given the ongoing iteration of motor control algorithms and the large-scale introduction of wide-bandgap semiconductors, the electrical architecture of this category of products will usher in a new round of technological upgrades, and its subsequent evolution merits close attention.