Precision Hall-effect angle sensor SoCs for automotive and industrial

November 20, 2014 // By Graham Prophet
Allegro MicroSystems’ A1332 and A1334 are high-resolution 360° angle sensor ICs based on magnetic circular vertical Hall (CVH) technology.

These contactless Hall-effect magnetic sensors, with their system-on-chip (SoC) architectures, provide high output refresh rates and low signal-path latency to support a variety of demanding automotive and industrial applications. Both devices are suitable for automotive applications such as electronic power steering (EPS) and transmission systems, and for sensing motor position, throttle/pedal position, and other parameters that require the accurate measurement of angles.

The A1332, with an onboard 32-bit processor and EEPROM for factory and customer programmability, includes segmented and Fourier linearisation functions for supporting challenging off-axis/side-shaft magnetic sensing configurations that are commonly found in electronic power steering and transmission applications. The A1332 also supports on-axis/end-of-shaft magnetic sensing configurations, and can produce high-accuracy angle measurements with an output refresh period of 32 µsec. The device incorporates a 2-wire I²C digital interface with signal path and I/O diagnostics for achieving higher reliability to meet ASIL automotive safety requirements.

The A1334, with its onboard digital signal processing functions and EEPROM for factory and customer programmability, is designed specifically for on-axis/end-of-shaft applications that require ultra-fast output refresh rates and low signal path latency. Its 4-wire 10 MHz SPI interface offers a 25 µsec output refresh period and a nominal signal-path latency of 60 µsec. The A1334 can operate directly off a vehicle battery, supporting a 4.5-14.5 V supply voltage range, while consuming 10 mA (max) of supply current. Like the A1332, the A1334 includes signal-path and I/O diagnostics for achieving ASIL safety requirements.

Both devices can operate in a low RPM mode, to support up to 12 bits of output resolution in lower angular velocity applications, and in a high RPM mode to support situations demanding faster refresh rates and lower single-path latency.

As part of their signal processing functions, the ICs include automotive-grade temperature compensation to provide accurate angle measurements over the full operating temperature and voltage range of the devices. The A1332 and A1334 are also air-gap independent over a wide magnetic