Requirements of tire pressure module for SMT crystal oscillators

May 16,2024
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In the era without tire pressure monitoring, data shows that 46% of accidents on highways are caused by tire failures, with tire blowouts accounting for over 70%, and the risk of accidents occurring frequently. And the shock wave generated by the tire explosion is enough to blow people up to 1 meter away. Under the influence of this distance and shock wave, human bones are broken in minutes, which looks very shocking

Therefore, the tire pressure monitoring device is particularly important for vehicle safety. It can monitor the tire pressure in real time, and will sound an alarm in the event of a tire blowout, leakage, or low air pressure, improving vehicle handling, reducing tire wear, shortening braking distance, and improving fuel economy, thereby improving safety on the road. Tire Pressure Monitoring System, abbreviated as TPMS, is a type of tire pressure monitoring system. TPMS has been recognized by the industry as an effective technology for explosion-proof tires. With the industry's emphasis on automotive safety, the third largest safety system has emerged. The emphasis on driving has become the third largest safety system after ABS and airbags.

The components of the tire pressure module mainly include sensors, capacitors, resistors, transistors, display circuits, quartz crystal oscillators, etc. In TPMS products, for the sake of high performance and safety, components that comply with the automotive standard (AEC-Q200) must be selected, that is, the components must meet the working temperature range of high and low temperature -40/125. In the selection of tire pressure crystal oscillators

Due to the lightweight and miniaturization of tire pressure modules, it is natural to choose lightweight packaging sizes for crystal oscillators, such as 3225 SMT packaging and 25202016 packaging. The frequency requirement of tire pressure crystal oscillators is very stable, and ceramic surface mount crystal oscillators with good sealing or metal surface mount crystal oscillators with impact resistance are often chosen. Due to the module being embedded in the tire, it is relatively less affected by external interference and has a longer service life compared to other vehicle grade crystal oscillators,

The high-frequency transmission circuit adopts the European tire pressure monitoring standard's 433.92M frequency, which is 24 times the external crystal frequency of 433.92MHZ/24MHz. Therefore, an 18.08M automotive grade crystal oscillator will be used. The role of crystal oscillator in tire pressure module: The role of crystal oscillator in the circuit is to provide basic clock signals for the system. Usually, a system shares a single crystal oscillator, making it easier for each part to stay synchronized. Some communication systems use different crystal oscillators for the fundamental frequency and radio frequency, which are maintained through electronic frequency adjustment