Single-chip sensor module for automotive TPMS

Rutronik is expanding its automotive portfolio with a compact sensor module from Bosch. The SMP290 is a fully integrated, Bluetooth-enabled single-chip solution for tyre pressure monitoring systems (TPMS). The module contains a Bluetooth Low Energy interface, an MCU, a MEMS pressure and temperature sensor, a two-axis MEMS acceleration sensor and a voltage measurement function. Diagnostics and communication are possible in both directions via the standardised BLE 5.4 interface. Measurement data or updates can be encrypted for transmission with the customer-specific application software. As the BLE standard is already utilised in vehicle components such as infotainment systems or radio keys, the sensor module seamlessly integrates into the vehicle's radio landscape.

Tyre pressure sensors play a decisive role in the service life of tires, as well as in fuel consumption, ensuring the road safety of vehicles. The SMP290 features a sensor readout ASIC whose core comprises the energy-efficient 32-bit MCU ARC EM6, which includes an FPU, DMA, and cache, for minimal power consumption. The 64kB RAM ensures a reliable start. The SMP290 also contains an analogue front end for the pressure sensor, temperature measurement via on-chip diode, the x- and z-axis acceleration sensor and battery voltage monitoring.

The module implements an advanced power management system on the ASIC with low-power circuits: configurable and high-efficiency DC-DC converter, low-noise bandgap references, low-drop-out regulator, an HF RC oscillator for efficient MCU operation, an accurate low-frequency RC oscillator for sleep mode control, and a low-power, low-frequency RC oscillator for deep sleep mode control. A coordinated digital control system optimises power consumption and lifetime of the TPMS sensor. Developers can choose between 0, 4 and 6dBm transmission power.

The sensor module is available in a 3.5mm x 4.5mm DFN housing with Wettable Flanks for AOI. It impresses developers with the low number of external components required and the correspondingly low TCO.

In terms of security, the SMP290 offers a low-power hardware implementation of AES-128 encryption. Additionally, it performs a CRC on all parameters consumed by the digital signal chain, as well as on traceability and stored runtime data.

Application examples include valve-based as well as in-tyre TPMS applications, and is compatible with remote keyless entry (RKE) systems.