ATS675: Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications

The ATS675 is the next generation of the Allegro^®True Power-On State (TPOS) sensor IC family, offering improved accuracy compared to prior generations. The ATS675 provides absolute zero-speed performance and TPOS information.

The device incorporates a single-element Hall IC with an optimized custom magnetic circuit that switches in response to magnetic signals created by a ferromagnetic target. The IC contains a sophisticated digital circuit designed to eliminate the detrimental effects of magnet and system offsets. Signal processing is used to provide device performance at zero target speed, independent of air gap, and which adapts dynamically to the typical operating conditions found in automotive applications, particularly camshaft-sensing applications.

High resolution peak-detecting DACs are used to set the adaptive switching thresholds of the device, ensuring high accuracy despite target eccentricity. Internal hysteresis in the thresholds reduces the negative effects of anomalies in the magnetic signal (such as magnetic overshoot) associated with targets used in many automotive applications. The resulting output of the device is a digital representation of the ferromagnetic target profile. The ATS675 also includes a low bandwidth filter that increases the noise immunity and the signal-to-noise ratio of the IC.

• Chopper stabilized; optimized for automotive cam sensing applications
• Rapid transition from TPOS mode to high accuracy running mode switchpoints
• High immunity to signal anomalies resulting from magnetic overshoot and peak-to-peak field variation
• Tight timing accuracy over full operating temperature range
• True zero-speed operation
• Automatic Gain Control circuitry for air gap independent switchpoints
• Operation at supply voltages down to 3.3 V
• Digital output representing target profile
• Undervoltage lockout (UVLO)
• Patented Hall IC-rare earth pellet system