TPMS (tire pressure monitoring system), airbag, and ABS (anti-lock braking system) are the three major safety systems in cars. Tire pressure is often referred to as "the blood pressure of the car", and having the right tire pressure is crucial for car safety. In the past, drivers checked tire pressure using scales or mallets, but passive monitoring is not convenient. Therefore, a tire pressure monitoring system using sensors, Bluetooth, RFID, and other technologies is necessary to provide faster and more automated solutions.

The tire pressure monitoring system monitors real-time tire pressure and temperature while driving, alerting drivers to leaks or low pressures to improve safety and vehicle stability. There are three main types of TPMS: direct TPMS, indirect TPMS, and compound TPMS.

Direct TPMS works by sending monitored air pressure signals from sensors to a central receiver when the car starts. If a tire's air pressure falls below a preset safety threshold, an alarm will immediately remind the driver to check and adjust it. Indirect TPMS works with vehicle ABS; when a tire loses air pressure, the smaller rolling radius causes it to rotate at a different speed than other tires. By analyzing this speed difference between tires, the system can determine if there's abnormally low tire pressure.

The above two monitoring methods have advantages and disadvantages. The direct TPMS has strong real-time performance, high accuracy and strong reliability, but the cost is high and the maintenance is complex. Indirect TPMS can make use of the existing wheel speed sensor on the car, and can not install additional sensors, so the cost is low, and the installation and maintenance is simple, but the accuracy is relatively poor.

Under the development trend of automobile intelligence and iot, the application of Bluetooth technology in tire pressure monitoring is also increasing. Bluetooth technology coupled with tire pressure monitoring system brings higher practicality and convenience. Compared with the traditional Sub 1G application scenario, BLE TPMS does not need a separate receiver, and can share the Bluetooth receiving device of the vehicle, reducing the peripheral devices required by the receiving end, and has a cost advantage. It can be connected with smart devices (such as mobile phone apps), providing a richer user interaction experience and remote monitoring functions, and accelerating the intelligent networking of automobiles.

At present, the industry including Jinjie Electronics, RF-star, Sensata, Shengrun Technology have launched BLE TPMS related chips and solutions. Jinjie IC launched the high integrated Bluetooth tire pressure monitoring chip SNP736, which is integrated with 8051 MCU, pressure MEMS, acceleration MEMS, 12bit ADC, high frequency (RF) emission, low frequency (LF) reception and other modules. Sensata Technologies' new BLE TPMS solution, launched in 2022, is available in both pullout and snap-on configurations to improve battery life. Based on SNP746, SNP746, SNP746, SNP746 introduces an integrated rear-mounted Bluetooth TPMS solution. The Bluetooth transmission power is adjustable from -20 to 4dBm, the tire temperature detection accuracy is ±3℃, and the tire pressure monitoring range is 100 to 900Kpa. According to the introduction, the Bluetooth tire pressure sensor has a built-in X/Z axis acceleration sensor, which supports three working modes of static, running and suspending, which can reduce power consumption and extend battery life.

It is worth mentioning that with the development of technology, many manufacturers have launched tire pressure monitoring systems to provide automatic positioning function. For example, the Bluetooth tire pressure monitoring system solution of RF-star and Sensata supports the automatic positioning function of the tire pressure monitoring sensor to automatically identify the corresponding tire position of each tire pressure sensor, and there is no need to manually match the corresponding tire position of the tire pressure sensor, which is convenient for the driver to quickly determine the problem tire.