Steer-by-wire sensor

“For innovations like steer-by-wire systems, position sensors are a critical component that must exhibit exceptional reliability, functional safety and accuracy,” it said. “The requirements for sensors in electric vehicles are heightened, necessitating excellent EMC robustness and stray field immunity. Simultaneously, solutions must be easy to integrate.”

MLX90427 as it will be called is designed to be used with a host MCU via an SPI bus.

Internally, is a three-axis Hall device with its own internal ADC and DSP to locally extract 14bit angular information from its measurements.

It has four distinct operating modes: standard rotary mode with two performance ranges, joystick mode for XYZ 3d position sensing and, for continuous rotation feedback in noisy environments, a 360° mode with stray field reduction.

The part is Grade 0 AEC-Q100 qualified and can be considered an ISO26262 ASIL C SEooC (safety element out-of-context) in systems up to ASIL D.

Self-diagnostics are included and dozens of parameters are tested or sensed for faults or failures.

Deviations from proper operation are separated into ‘fatal faults’ where software execution cannot be trusted, ‘errors’ where a measurement cannot be trusted, and ‘warnings’ where a latent fault has been found. Each level has a different automated response leading to recovery or entry into one of several ‘safe states’.

In safety-critical applications like steering columns, according to the company, “MLX90427 with its stray field immunity and EMC robustness can be deployed alongside sensors utilising differing sensing technologies, such as the inductive sensing MLX90513, to attain the highest levels of functional safety through heterogeneous redundancy”.

For homogeneous redundancy, a dual die 16pad TSSOP version is scheduled for Q4 this year. The standard 8pad SOIC version is available this month.

Power can be applied at 5V (18V abs max) or 3.3V (4V abs max). Consumption is typically 9.5mA in either case.

Operation is also over -40 to +160°C.

Use is also foreseen in gearbox shifting and infotainment control knobs.

Find the steer-by-wire sensor on this product page