Melexis Aims To Simplify Automotive System Design With Inductive Sensor
The new MLX90514 dual-input inductive sensor processes signals from two coil sets simultaneously to compute differential or vernier angles on-chip, reducing complexity in vehicle control systems.
Melexis has released the MLX90514, a dual-input inductive sensor integrated circuit (IC) designed to simplify complex position-sensing applications, particularly in the automotive sector. This new device addresses the growing need for accurate, high-speed position data in systems such as steering torque feedback, steering angle sensing, and steer-by-wire implementations, all of which demand dual-channel sensing.
Melexis has developed the MLX90514 dual-input inductive sensor to tackle complex position sensing in automotive systems. Image used courtesy of Melexis
MLX90514 Dual-Input Inductive Position Sensor
Traditional solutions for position sensing in vehicle control systems often involve using two separate single-channel ICs or magnetic sensors, which can increase system complexity, component count, and cost. The MLX90514 dual-input inductive position sensor tackles these issues by integrating the processing for two independent channels into a single chip. It simultaneously processes signals from two sets of receiver coils to compute differential or vernier angles directly on-chip, offloading processing from the host system’s microcontroller. This on-chip signal processing and latency compensation improve accuracy and dynamic behavior.
The MLX90514 controls an inductive sensor system composed of a transmitting coil, one or two targets, and two sets of receiver coils, each with three coils. The on-chip LC oscillator generates an electromagnetic field with the transmitting coil. This field, in turn, induces angle-dependent voltages in the receiving coils, which are then captured and processed by the MLX90514’s internal digital signal processing units.
Block diagram for the MLX90514 dual-input inductive sensor IC. Image used courtesy of Melexis
On-Chip Processing for Inductive Sensing
The MLX90514 features synchronized dual-channel operation with zero latency, which is critical for real-time and high-accuracy applications. It offers a maximum error of ±0.36° electrical for each inductive channel. The device is also immune to magnetic stray fields, complying with the ISO 11452-8 standard. This is particularly beneficial in a vehicle environment where electromagnetic interference is common.
In terms of physical design, the IC’s ability to handle small inductive input signals allows for the use of compact coil designs and tighter PCB layouts. This flexibility enables the development of smaller, highly integrated sensing modules without compromising performance, which is an important consideration in space-constrained automotive designs.
Flexible Interface and Functional Safety
The MLX90514 provides multiple output modes, accommodating various system architectures. It supports standard formats of SENT and SPC, as well as enhanced serial messages that include error codes. The SENT/SPC output can handle a 24-bit payload, allowing for the transmission of two synchronized 12-bit channels. For embedded applications, the device offers an SPI protocol for fast and protected data transfer and programming. An additional PWM input channel allows the sensor to read signals from external sources, such as a magnetic sensor, enabling the combination of multi-turn angle and torque data within a single device.
Because the MLX90514 is designed for robust operation in demanding automotive environments, it features overvoltage and reverse-polarity protection up to ±24 V and operates in an ambient temperature range from -40 °C to 160 °C. The device is AEC-Q100 qualified and compliant with ISO 26262 ASIL C(D) as a Safety Element out of Context, confirming its suitability for high-level functional safety requirements.
The MLX90514 is built to simplify designs in absolute rotary or linear motion/position sensing in automotive applications. Image used courtesy of Melexis
Absolute Rotary or Linear Motion Sensing
The Melexis MLX90514 is a versatile new dual-input inductive sensor IC that integrates the processing and synchronization of two channels onto a single chip. By computing differential and vernier angles on-chip, it reduces the computational load on the host system and lowers the overall bill of materials. The sensor’s high accuracy, low latency, and robust interface options make it suitable for a range of critical applications. These include contactless absolute rotary or linear position sensing, steering torque sensors, steering angle sensors, and high-resolution rotary and linear sensors in next-generation electrified and autonomous vehicle systems.
