Programmable Hall sensor is optimized for safety-critical applications

February 14, 2017 // By Christoph Hammerschmidt
Allegro Microsystems Europe has introduced a dual-chip programmable Hall sensor IC for safety critical applications in automotive environments. The A1346 features full chip/die redundancy for the applications as well comprehensive diagnosis functions without interrupting the application. In cases when both chips deliver inconsistent data, the controller can determine which chip’s output data are correct.

The A1346 contains two high-precision, programmable. Linear Hall effect sensors with open drain output. An external programming option ensures flexible data path configuration to meet customer-specific output signals derived from a single magnetic input signal. Each one of these monolithic BiCMOS ICs offers a system-on-chip configuration with a Hall element, precise temperature compensation to reduce the Hall sensor’s specific sensitivity and offset drift, a small-signal amplifier, a patented dynamic offset suppression, enhanced output linearization and sweeping diagnosis.

A significant feature of the A1346 is the capability to generate a highly linear output for non-linear input magnetic fields through a 16-stage linearization circuit that can be adjusted by the customer. The linearization coefficients are stored in a look-up table in the EEPROM.

Besides SAEJ2716, the device supports two proprietary SENT protocols: SSENT and ASENT. Both enable the user to attach up to four sensors to one SENT line to reduce cost. SSENT offers sequential access to the sensors and has a very small overhead to maximize the sensor bandwidth on this single line. This minimizes the impact to the system overall performance caused by attaching multiple sensors to one line. In contrast, ASENT enables randomly accessing the sensors attached to a joint signal line. Both protocols enable the system to switch single sensors into the diagnosis mode while the other sensors continue to be active. This feature ensures highest diagnosis coverage and at the same time maximum availability of the sensors.

Application fields are, for instance, torque measurements in electric steering systems (EPS), brake sensing like pedal travel, brake piston position, and brake pad wear; and measuring the position of the clutch resp. the transmission actuator lever.

The A1346 comes in a14-pin TSSOP SMD package with tin-plated leadframe.

Data sheet: http://www.allegromicro.com/en/Products/Magnetic-Linear-And-Angular-Position-Sensor-ICs/Linear-Position-Sensor-ICs/A1346.aspx