Inductive sensor interface IC meets automotive requirements

December 09, 2015 // By Christoph Hammerschmidt
Chipmaker Microsemi has introduced an interface device for inductive sensors that supports the SENT protocol, survives temperatures up to 150°C and is qualified according to the AEC Q100 automotive standard. Inductive sensing competes against Hall sensors in many applications in the car.

The LX3302 improves the LX3301A with an extended temperature range to 150 degrees Celsius, and a richer set of system interfaces which include analogue sine/cosine outputs, single edge nibble transmission (SENT) and Peripheral Sensor Interfaces (PSI5), as well as the standard analogue output and pulse width modulated (PWM) output. In addition, the LX3302 has double the EEPROM available in the LX3301A, allowing for eight-point calibration, versus six-point calibration, which increases system accuracy by 1-bit and permits less precise, lower cost sensor manufacturing. The device features LVDT principles, resulting in superior immunity to noise and interference.

According to Microsemi, inductive sensing technology can replace the incumbent Hall-effect sensors, which are susceptible to external magnetic fields and/or metal objects in close proximity. Inductive technology eliminates the magnet, thereby improving immunity to such interference, the company claims. In addition, inductive sensing provides improvements in temperature stability, reliability, safety and system costs.

As sensors are the key element in the feedback loop of virtually all closed loop systems, the LX3302 is ideal for a variety of applications related to control systems and industrial automation, including linear displacement measurement (fluid level sensing, gear position for transmission actuator position and brake lamp switch/proximity detection) and angular motion measurement (robotic arm position, rotating shaft position, pedal position and rotary controls). It also meets automotive application requirements, including AECQ100-certified grade 0, and comes with Production Part Approval Process (PPAP) documentation support.

The implementation of sensors continues to expand throughout the automotive and industrial markets. MEMS Journal estimates that the number of new light vehicles (cars and light trucks) shipped worldwide will grow from approximately 85 million in 2014 to 110 million by 2020. These vehicles currently feature an average of 60-100 sensors on board, but as cars are rapidly getting "smarter," the number of sensors is projected to reach as many as 200 sensors per car. This translates to approximately 22 billion sensors used in the automotive industry