Two-chip pressure sensor and signal conditioning

This paper reports a newly developed tire pressure monitoring sensor (TPMS) incorporated with a digital sensor signal processing ASIC. The TPMS provides the compensated outputs of pressure, temperature, and battery voltage. The combination of the concise, cost-effective two-chip plastic package and the rigorous, simple calibration algorithm has been successfully adapted to this TPMS application. A calibration algorithm has been established from three characteristic equations with ten coefficients, obtained by relating the measured pressure, temperature and voltage ADC readings. The memory size of the algorithm firmware is less than 1Kbyte and as a result, the power consumption of this TPMS measurement is proven to be only 9.7 /spl mu/A-sec, which is well below the energy consumption that would allow a 10-year battery life. It has been successfully demonstrated that this TPMS meets the desired high-accuracy performance, providing the maximum pressure measurement errors less than 1.5% FSO over -40/spl deg/C to 125/spl deg/C and 2.1 VDC to 3.0 VDC battery voltage.