background

In modern society, people are under increasing pressure, and the quality of sleep is particularly important. As a popular wearable smart device, smart bracelet integrates many functions, such as motion monitoring, sleep tracking, heart rate measurement, body temperature detection, etc. Its internal circuits are concentrated on a small PCB to achieve low power consumption and high precision balance. Heketai will explain its composition and matters needing attention in PCB design below.

Composition and principle

Smart bracelet usually consists of RF circuit unit, clock circuit unit, memory circuit unit, sensor circuit unit and main control MCU unit, and its functions mainly include sleep detection, heart rate measurement, body temperature detection and so on. Sleep monitoring is to sense whether our bodies have big movements during sleep. The body motion recorder has three-axis sensors that can sensitively record slight movements from three directions.

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The common methods of heart rate measurement are photoelectric transmission measurement and ECG signal measurement. The photoelectric transmission measurement uses the heartbeat to cause the change of blood transmittance. The principle of ECG signal measurement is similar to that of hospital ECG detection. The heart rate value is obtained by using the conductivity of human tissues and body fluids and collecting the changes of surface electrodes. High-precision NTC thermistor is used for temperature detection, and the accuracy can reach 0.01 degree in the temperature range of 36-42 degrees, and the resistance accuracy is 0.05%. However, it must be closely fitted to the wrist, otherwise the measurement accuracy may be affected by heat radiation.

Precautions for PCB

PCB design of smart bracelet should pay attention to many matters. First of all, the layout should be partitioned, and each circuit unit should be reasonably divided. The clock and crystal oscillator circuits should be short and avoid data lines. The key wiring should be protected by copper plating and grounding, and the crystal oscillator part should be excavated with copper. Secondly, as a key part, RF circuit is based on low-power Bluetooth transmission, and the influence of antenna shape, layout and shell material should be paid attention to, and RF antenna engineers should participate. At the same time, ESD protection design and detection should be done well to adapt to different regional standards. It is also necessary to reserve the system upgrade interface, and determine the upgrade methods such as USB interface or wireless push in the early stage.

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To sum up, the layout of smart bracelet is the core of realizing multi-functional integration, so it is necessary to consider the component selection of each module. For example, Heketai NMOS tube A03420 can be used in the control of charging loop to improve reliability and reduce loss; To maintain battery balance, HKTQ30P03 of Heketai can be used, which has low resistance, high efficiency and fast response. Schottky diode can be used for interface signal protection, and SD103AW is recommended. Through functional partition layout, combined with short-distance wiring and signal shielding design, health monitoring, wireless transmission and low power consumption can be balanced in a compact space, and Heketai lays a hardware foundation for high-precision data acquisition and long-term reliable operation of smart bracelets.

company introduction

Heketai, founded in 1992, is a high-tech and specialized new enterprise integrating R&D, design, production and sales of professional components.

Products include:

1. Semiconductor packaging materials; 2. Passive components, mainly including: resistance, capacitance and inductance; 3. Semiconductor discrete devices, mainly including MOSFET, TVS, Schottky, voltage regulator, fast recovery, bridge stack, diode, triode and power device, power management IC and other integrated circuits.

Heketai has two intelligent manufacturing centers:

1. The manufacturing center in South China of China is located in Heketai Science and Technology Intelligent Manufacturing Park, Boluo County, Huizhou City, with a construction area of 75,000 ㎡ and more than 1,000 sets of advanced equipment and testing instruments. It is a local supporting group logistics distribution center, and Dongguan Tangxia Production Center is the current production base;

2. The manufacturing center in the southwest of China is located in Kechuang Center, Shunqing District, Nanchong City, Sichuan Province, with a workshop area of 35,000m2 and about 2,000 advanced equipment and testing instruments;

In 2024, Heketai expanded its product line in an all-round way and established three subsidiaries in Nanchong, Sichuan, namely Shunxin Semiconductor, Nanchong Anhao and Nanchong Jingke, which are mainly responsible for the research and development and production of semiconductor packaging materials; After the product line is broadened, it will meet the needs of customers to the greatest extent.

Heketai adheres to the business policy of customer first, quality first, innovation-driven and people-oriented, and provides customers with one-stop application solution services. At the same time, Heketai provides comprehensive services such as OEM OEM OEM for semiconductor chip and discrete device packaging and testing.

Heketai has accumulated rich core technology reserves in integrated circuit design, chip testing, discrete device process design and reliability experiments, and has more than 100 national invention patents and utility model patents.

Heketai has passed ISO9001, ISO14001 and IATF16949 system certification.

Products are widely used in power supply, lighting, medical electronics, small household appliances, communications, security instruments, industrial control, automotive electronics and other fields.

Sweep and contact Heketai.

Sales Tel: 18823438533 (WeChat with the same number)

Landline: 0755-82565333

Email: hkt@heketai.com.