Tire Pressure Monitor
Tire pressure monitoring systems (TPMS), required in the US and increasingly elsewhere, demand a high-performance, frequency hopping receiver such as Silicon Labs’ Si4xxx EZRadioPRO® that can be shared with RKE/PKE access systems. The wheel component of TPMS monitors the pressure and temperature every few seconds and transmits the data over RF frequency. The monitoring is typically done in short bursts every few seconds to save battery life. The tire module batteries are rated at 85 °C max and are expected to last 7-10 years in the application. Most of the time, batteries are sealed into the TPMS module and cannot be replaced. Coupled with an RF transmitter and pressure sensor, Silicon Labs’ C8051F99x with RTC wake-up is the lowest power solution available.
An alternate option is the Si401x, which integrates the MCU and TX functions in a single chip.