Smaller, lower power tyre pressure monitoring

May 12, 2016 // By Graham Prophet
Melexis is offering its third generation of tyre pressure monitoring ICs, which it presents as delivering highest accuracy while drawing the lowest current and taking up less board space than previously achieved.

MLX91804 comes in a robust 14-pin DFN type leadless package, this product has a 60% smaller footprint and draws three times lower sleep mode current than any competing TPMS IC on the market, the company asserts. It incorporates a microcontroller and MEMS-based pressure sensing element, as well as energy-efficient 315/433 MHz wireless transmitter (supporting data rates up to 150 kbits/sec) and 125 kHz receiver for communication with the vehicle’s relevant electronic control unit (ECU). A 16 kB embedded program memory is included for the storing of custom application data/libraries. There is a built-in single or dual axis high-g range accelerometer to support all market available wheel sensor auto-location functionalities.


The combination of minimal footprint and high degrees of integration offered by the MLX91804 means that a significant reduction in PCB size can be realised, and the low power consumption (in sleep mode as well as when fully operational) permits a downsizing of the specified battery. The result can be a smaller size and lower weight sensor module. Together with high-g range and fast data acquisition accelerometer, it also represents a step closer to the tyre mounted sensor (TMS) implementations that automotive Tier 1 suppliers are looking to use in the future. Precision and low power fast pressure measurements allow extra new features to be implemented such as tyre filling assistant without a visible impact on battery life. The -40°C to 125°C operational temperature range and strong resilience to shock (10000g) allow the MLX91804 to deal with a harsh in-tire environment.