Automotive magnetic position sensors are safety compliant

May 06, 2016 // By Graham Prophet
Presented in a System-in-Package (SiP) format, ams’ AS517x devices include full data path diagnostics and enhanced self-test capabilities to enable automotive systems to comply with relevant safety standards.

ams has released its first magnetic position sensors developed using the automotive industry’s programme for ISO26262 safety compliance. They are also ams’ first magnetic position sensor in a System-in-Package (SiP) format, a space savings package, that enables lower system costs and the placement of the sensor device in environments that are prohibitive to PCB based packages.

 

AS5170 and AS5171 sensors were developed as SEooC (Safety Element out of Context) devices, as defined in the ISO26262 functional safety standard. Designed to meet demand for automotive safety features built into critical vehicle systems, the AS517x parts are ams’ first magnetic position sensors to provide full data path diagnostics, enabling automotive system OEMs to achieve a higher level of ISO26262 system-level compliance.

 

The diagnostic system built into the AS517x series tests the entire device, from the Hall sensor front end, through the DSP engine which converts raw measurements of magnetic field strength into sine and cosine vectors, to the back-end interfaces and pins.

Qualified to AEC-Q100 Grade 0, the sensors accurately measure absolute angle of rotation. Their high 12-bit output resolution enables precise measurements, even for reduced angular excursions down to a minimum arc of 90°. The devices are suitable for a range of safety-critical automotive applications including chassis height, gear shifters, electronic power steering, exhaust gas recirculation, and brake pedal as well as throttle position sensing.

 

The AS5171 comes in an SiP format, which integrates the sensor die and capacitors in a single, encapsulated three-pin package. The SiP offers improved ESD and EMC performance, as well as enhanced supply protection. The Supply and Output pins are protected against over-voltages up to +20V. The Supply pin also offers -20V of protection against reverse polarity. The AS5171A provides an analogue output, and the AS5171B provides a digital output, which may be programmed either as a PWM interface or as a SENT-compliant interface. The analogue AS5170A and digital AS5170B ICs are housed