Abstract: A single integrated sensing chip with multi-functions for tire pressure monitor system (TPMS) comprises: a pressure sensor, an accelerometer, a temperature sensor, and an ASIC (Applied Specific Integrated Circuit) that implements signal conditioning and digitalizes pressure output. The accelerometer incorporated for vehicle motion is used to determine centrifugal acceleration or three-axial acceleration of the rotating wheel, and used for the TPMS sensor wake-up from “power down” mode, or when the velocity of the vehicle is higher than certain speed threshold, which is more robust and lower in cost than the mechanical vibration switch and is naturally integrated with the electronic control unit. The accelerometer can be used for regular motion sensing to monitor the dynamic stability.

Abstract: Several micro-machined, ultra-profile two-axis and three-axis accelerometers are fabricated by CMOS-compatible process, which makes them suitable for volume production. The x, y axis signal is based on natural thermal convection, and z-axis signal may be based on thermal convention or piezoresistive in nature. The bulk MEMS (Micro-Electro-Mechanical-Systems) process is based on Deep Reactive Ion Etching (DRIE). After the front-end fabrication process, the accelerometers are packaged at wafer level by glass frit and/or anodic bonding, which lowers the device cost.