Sensor IC offers full diagnostics, SENT/PWM output

Article By : Allegro MicroSystems

A key feature of the A1346 is its ability to produce a highly linear device output for nonlinear input magnetic fields.

Allegro MicroSystems has rolled out a dual die, highly programmable linear hall sensor IC targeting safety critical applications.

The A1346 sensor IC incorporates full die redundancy with the added benefits of full diagnostics, which, according to the company, allow for a higher level of diagnostics without interruption to the application (where diagnostics would otherwise render a die temporarily nonresponsive). The combination also allows the controller to know which die to trust when the output of the die does not agree. This new device is primarily targeted at the automotive market with end applications to include EPS torque sensing, braking (pedal travel, piston position, brake wear) and transmission actuator/clutch position sensing.

The signal paths of the A1346 provides flexibility through external programming that allows the generation of accurate and customised outputs from an input magnetic signal. The A1346 is an especially configurable and robust solution for the most demanding linear field sensor applications.

The BiCMOS, monolithic integrated circuits incorporate on each SoC a Hall sensing element, precision temperature compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, advanced output linearisation circuitry, and advanced diagnostic detection.

A key feature of the A1346 is its ability to produce a highly linear device output for nonlinear input magnetic fields. To achieve this, the device features 16-segment customer programmable linearisation, where a unique linearisation coefficient factor is applied to each segment. Linearisation coefficients are stored in a lookup table in EEPROM.

The A1346 contains two proprietary SENT protocols in addition to SAEJ2716: SSENT and ASENT. Both protocols enable the user to attach up to four devices on one SENT line to reduce system costs. SSENT provides sequential access to the sensors connected to the same line. SSENT provides a very low overhead method to maximise the sensor bandwidth on this single SENT line, minimising impact on system performance. ASENT provides random access to all the sensors on the common SENT line. Both protocols allow individual sensors on the same line to enter diagnostic mode while the other sensors continue to respond to queries, allowing for the highest diagnostic coverage while maintaining 100% availability of the sensor solution.

The A1346 is available in a surface-mount, lead (Pb) free 14-pin TSSOP package (LE suffix), with 100% matte-tin leadframe plating.

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