Volkswagen to Use Infineon Sensor Chip in Electric Power Steering Systems

In the Volkswagen electric power steering systems produced in Braunschweig, Germany, in each case two Hall sensors from Infineon are responsible for accurate steering torque sensing. They measure the steering force exerted and the steering angle, and relay this information to the control unit of the electric power steering system. The latter, in turn, then ensures that the control of the motor responsible for the electric power steering is optimized in terms of the required assist force and energy. The Hall sensors are incorporated in the sensor module of the system supplier to the Braunschweig Business Unit – Valeo Schalter und Sensoren GmbH.

Fundamentally, the TLE4998 Hall sensors are suited for applications requiring accurate rotation and position detection. Automotive applications include, for example, pedal, throttle or gear stick position detection, suspension control or direct torque sensing for electric power steering systems. The special characteristics of Infineon’s Hall sensors are advantageous in this arena. Their temperature compensation and high long-term stability due to stress compensation contribute to a consistently high and robust precision of the signals – throughout the vehicle’s service life and regardless of weather conditions. The TLE4998 Hall sensors support system reliability by a protected digital interface.

Technical information concerning the Hall sensor: unique stress compensation

Infineon is the only manufacturer in the world to provide Hall sensors offering the three interfaces: Short PWM Codes (SPC), Pulse Width Modulation (PWM) and Single Edge Nibble Transmission (SENT). In this way Infineon supports the conversion from analog to digital communication between sensor and control unit of the vehicle steering system. SENT and SPC interfaces allow the system supplier to respond flexibly to automakers’ interface requirements.

Compared to today’s mainstream PWM communication, the SPC interface enhances the accuracy and reliability in safety critical automotive applications as it allows synchronized data transmission with the control unit. This functionality signifies that the microcontroller in the control unit can selectively collect sensor measurement data for processing and has the current measurement data available.

The TLE4998 is designed so as to be capable of compensating for temperature fluctuations and mechanical stress over the lifetime of a vehicle. It has a sensitivity stability three to four times better than that of sensors without stress compensation.

The three interface versions of the TLE4998 family are TLE4998C (SPC), TLE4998P (PWM) and TLE4998S (SENT). Each is available in two packages: PG-SSO-3 with three pins and PG-SSO-4 with four pins. The PG-SSO-4 package version, which is only 1 millimeter thin, allows inserting Infineon’s TLE4998 Hall sensors into even very small air-gaps, as are common in the electric power steering system. Furthermore, a package version is available with two external ceramic capacitors, further improving the EMC capabilities of the sensor and dispensing with external capacitor connection.