TLE4941PLUSC

The TLE4941PLUSC from Infineon Technologies is a state-of-the-art differential Hall-effect speed sensor IC designed specifically for demanding automotive wheel speed sensing applications. As part of Infineon’s XENSIV™ sensor portfolio, this device represents the latest generation of the highly successful TLE4941 family, with hundreds of millions of units already deployed in the field. Built on advanced BiCMOS technology, the TLE4941PLUSC integrates two Hall probes (with 2mm spacing for small pitch compatibility), a differential amplifier, comparator, digital signal processing, and a two-wire current output stage on a single monolithic chip. The differential sensing principle makes the device immune to stray magnetic fields and common-mode disturbances, ensuring reliable operation in the harsh automotive environment. A sophisticated dynamic self-calibration algorithm automatically cancels both magnetic and device offsets within the first 4 magnetic edges after power-up, with an initial calibration delay of just 300µs maximum. The first-edge-detection feature provides a reliable output signal even before full calibration is complete. The two-wire current interface (7mA low / 14mA high output) minimizes wiring complexity and is the standard interface for active wheel speed sensors. With its integrated 1.8nF overmolded capacitor (C variant), the device offers enhanced EMC robustness and microbreak resistance without any external components. Qualified to AEC-Q100 automotive standards and ISO 26262 ASIL B(D) compliant for functional safety, the TLE4941PLUSC in the PG-SSO-2 package is the ideal choice for ABS, ESP, and vehicle dynamics control systems.

The TLE4941PLUSC operates on the principle of the Hall effect, where a voltage difference (Hall voltage) is generated across a current-carrying conductor placed in a magnetic field perpendicular to the current flow. The device contains two Hall probe elements separated by a 2mm distance on the silicon die. When a toothed or magnetic encoder wheel rotates near the sensor, the magnetic field strength at each Hall probe changes differentially as the teeth/poles pass by. The differential signal from the two Hall probes is amplified by a preamplifier and fed to a comparator that detects zero crossings of the differential magnetic field. The comparator output drives a current modulator that switches between two current levels (7mA low, 14mA high) on the two-wire supply line, encoding the speed information as current pulses that can be detected by the ECU. A digital signal processing (DSP) block implements dynamic self-calibration, continuously adjusting offset DACs to cancel out temperature-dependent and mechanical offsets in real-time. This calibration algorithm requires approximately 4 magnetic edges to reach full accuracy after power-up. The device also includes a bandgap reference for stable biasing, an oscillator for system clock, power supply management with undervoltage detection, and ESD protection structures. When no magnetic edges are detected for an extended period (> 590ms), the device automatically resets its calibration and enters a low-power standby state, re-calibrating when movement resumes. The overmolded 1.8nF capacitor (C variant) is integrated into the package for enhanced EMC performance and protection against microbreaks in the wiring harness.

Note: The PG-SSO-2 is a 2-pin single-sided outpackage (SSO) for PCB mounting. The TLE4941PLUSC uses a two-wire current interface protocol where both power and speed information are transmitted over the same two wires. The supply current level (7mA or 14mA) encodes the magnetic state. The C variant includes an integrated 1.8nF overmolded capacitor between VDD and GND for EMC filtering.

• Anti-Lock Braking Systems (ABS): The primary application — each wheel uses a TLE4941PLUSC sensor to measure rotational speed, providing the ABS controller with precise wheel speed data for slip control and brake modulation
• Electronic Stability Program (ESP): Wheel speed data from these sensors is used by ESP systems for vehicle dynamics control, including traction control and yaw stability management
• Transmission Speed Sensing: Used in automatic and dual-clutch transmissions for input and output shaft speed measurement, supporting gear shift control and torque converter slip detection
• Chassis Control Systems: Deployed in active suspension systems, electronic power steering (EPS) assist calculation, and other chassis control functions requiring wheel speed information
• Automotive Safety Systems: Serves as a key input to vehicle safety systems including rollover protection, hill start assist, and hill descent control systems
• Motor Position Sensing: Used in automotive motors (blower, coolant pump, fuel pump) for closed-loop speed control and tachometer feedback
• Industrial Speed Sensing: Suitable for industrial motor control, conveyor systems, and rotational speed measurement applications requiring high reliability
• EV/HEV Applications: Used in electric and hybrid vehicles for wheel speed sensing in regenerative braking control and vehicle dynamics management