In the current smart bracelet market, Xiaomi bracelets have accumulated over many generations. Based on the light-weight design that is most like a “bracelet” and rich in sports health monitoring functions, it has been recognized by many consumers and occupies a large market share. Recently, Xiaomi Mi Band 7 was officially launched, and the screen size and functions have been further improved.
The appearance design of Xiaomi Mi Band 7 continues the consistent family-style design style, but the screen size has been upgraded from 1.56 inches of Xiaomi Mi Band 6 to 1.62-inch, and the resolution has also been upgraded from the previous generation 152×486 to 192×490, and the viewing area has been improved. 25%, the look and feel is more delicate and smooth. In addition, the long-awaited AOD screen display function for Xiaomi Mi Band users has been added, and there are many custom screen display patterns.
In terms of functional configuration, in addition to basic functional applications, Xiaomi Mi Band 7 supports 24-hour heart rate and blood oxygen monitoring. It supports 120 sports modes, covering various sports scenarios, and provides professional sports health data analysis and suggestions such as maximum oxygen uptake, training load, recovery time, and training effect. The NFC version also supports bus, subway, access control card swiping, and Xiaoai voice assistant. Let’s take a look at the detailed teardown report of this product.
Xiaomi Mi Band 7 Teardown
Go to the teardown section. Heat the edge of the screen, soften the glue to pry open the screen cover, and connect the inner screen cable to the motherboard through the ZIF connector.
The circuit on one side of the screen cable.
The circuit on the other side of the screen cable is printed with the words Visionox on the front and back of the cable.
There is a large NFC antenna attached to the back of the screen.
Parade TMA525 point-touch capacitive touch screen controller with 32-bit ARM Cortex™ CPU registers, configurable noise reduction technology. Works with battery chargers and monitors and supports DualSense™ for waterproof and wet finger tracking.
The copper sheet connecting the screen cable to the motherboard.
The internal structure of the Xiaomi Mi Band 7 cavity, the motherboard is fixed by screws, and the motherboard is covered by a large area shield.
A bluetooth antenna is attached to the cavity wall, and next to it is a ZIF connector for connecting the screen cable.
Remove the screws to open the motherboard, the battery is fixed inside the motherboard, and there are cables connected to the bottom sensor module.
Take out the main components in the cavity, including the main board, battery and sensor module board.
Cavity bottom structure.
Two metal copper post connectors for charging the bracelet.
The microphone pickup hole is pasted with a waterproof and breathable membrane.
Two rectangular magnets for attaching to the magnetic charger.
Sensor module lens.
Xiaomi Mi Band 7 motherboard, battery and sensor module teardown.
The sensor module circuit is equipped with LED lights for blood oxygen and heart rate detection, a sensor for receiving light, and a front-end chip.
TI AFE44S30 analog front end for optical biosensing applications such as heart rate monitoring (HRM) and peripheral capillary oxygen saturation (SpO2 ) measurement. The device supports up to eight switchable light-emitting diodes (LEDs) and four photodiodes. Up to 24 signal phases can be defined and the signal can be acquired from each phase in a synchronized manner.
The photodiode current is converted to a voltage by a transimpedance amplifier (TIA) and digitized using an analog-to-digital converter (ADC). ADC codes can be stored in first-in, first-out (FIFO) blocks of 128 samples. The FIFO can be read using the SPI interface. This AFE also features a fully integrated LED driver with 8-bit current control. The device features wide dynamic range transmit and receive circuitry that facilitates detection of very small signal levels.
The sensor module board is connected to the ZIF connector of the main board through a cable.
Xiaomi Mi Band 7 built-in battery model: PL411525, rated voltage: 3.87V, charging limit voltage: 4.45V, capacity: 180mAh/0.70Wh, from EVE Energy Co.,Ltd.
Silkscreen information on the other side of the battery.
Battery circuit protection board circuit.
Screen printing ZDSA’s integrated lithium battery protection IC is used for battery overcharge, overdischarge, overcurrent and other protection functions.
Heat and remove the shield on the motherboard.
The circuit on the motherboard side.
The circuit on the other side of the motherboard.
The rotor motor with silk screen “232” is used for vibration feedback of bracelet human-computer interaction.
A metal shrapnel used to connect the connector at the bottom of the cavity to charge the bracelet.
ZIF connector for connecting sensor module cables.
RENESAS DA14706 bluetooth Low Energy wireless SoC. Single-chip integrated power management unit, hardware Voice Activity Detector (VAD), Graphics Processing Unit (GPU) and Bluetooth® Low Energy connectivity to provide smart IoT devices with advanced sensor and graphics capabilities and seamless, ultra-low Powerful and always-on audio processing power.
DA14706 consists of Arm® Cortex®-M33 processor + Cortex-M0+ sensor node controller, integrates 2D GPU and display controller, supports DPI, JDI parallel, DBI and single/dual/quad SPI interfaces. The configurable MAC supports Bluetooth 5.2 Low Energy and proprietary 2.4 GHz protocols. Integrated 720mA JEITA standard USB charger, supports rechargeable Li-ion/Li-polymer battery. Ultra-low power hardware VAD for seamless and always-on audio processing.
The crystal that provides the clock for the bluetooth wireless SoC.
Silkscreen 4ALP IC.
NXP silk screen 110TB22 NFC chip.
NFC chip peripheral crystal oscillator.
Willsemi ESD5641D12 TVS diode for electrostatic protection of charging terminals.
Laser carving G032 2ZRW’s MEMS microphone for Xiaomi Ai voice interaction pickup.
Winbond 25N01GW Serial Interface (SPI) SLC NAND with 128MB capacity. It has fast erasing and programming performance, more than 100,000 erasing and programming cycles, and a data retention period of more than 10 years. It is used to store systems and data.
Silkscreen APM IC.
Silkscreen G8LW IC.
Silkscreen Z7ELW IC.
ST LSM6DSOWTR accelerometer + gyroscope sensor.
Silkscreen L2C0C IC.
All components of Xiaomi Mi Band 7.
The appearance of Xiaomi Mi Band 7 still adopts the classic design, and the screen size is increased to provide more display content. With the same improved screen resolution, the more delicate look and feel can effectively improve the user experience. But at the same time, the size and weight of the bracelet have also increased. For users who are used to the previous generation products, it may take some time to adapt.
In terms of internal structure design, Xiaomi Mi Band 7 is similar to the previous generation. The screen, motherboard, battery, and sensor modules are stacked layer by layer, with a high degree of integration, and the components are mostly connected by connectors, which improves the convenience of assembly. A large-area NFC antenna is set on the back of the screen for near-field communication. The Pray TMA525 point-touch capacitive touch screen controller is installed on the screen cable for screen touch operation.
The sensor module consists of LED lights for blood oxygen and heart rate detection, light receiving sensors and TI AFE44S30 analog front end for optical biosensing applications. The main control chip is the Renesas DA14706 bluetooth low energy wireless SoC, which integrates rich functions on a single chip, providing advanced sensor and graphics functions, as well as seamless, ultra-low power consumption and always-on audio processing capabilities. The bracelet has a built-in EVE 180mAh battery and is equipped with an integrated lithium battery protection IC. The power input is also provided with Willsemi ESD5641D12 TVS diodes for electrostatic protection of the charging terminals.
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