Magnetic sensors come in space-saving package

April 26, 2016 // By Christoph Hammerschmidt
Targeting safety-critical automotive applications, the analog technology experts form Austria-based AMS AG have developed two magnetic position sensor chips. As required for these applications, the AS5170 and AS5171 meet the functional safety standard defined in ISO 26262. Plus, the sensors are provided in the space-saving System-in-Package (SiP) format.

The AS5170 and AS5171 sensors were developed as SEooC (Safety Element out of Context) devices, as defined in the ISO26262 functional safety standard. In line with the requirements of the safety-relevant applications they are designed for, the sensors provide full data path diagnostics. 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.

The AS517x series of sensors, which are qualified to AEC-Q100 Grade 0, very accurately measure the absolute angle of rotation. Their 12-bit output resolution enables precise measurements, even for reduced angular excursions down to a minimum arc of 90°. Thus, the devices are suited for applications like chassis height, gear shifters, electronic power steering, exhaust gas recirculation, and brake pedal as well as throttle position sensing.

The AS5171 comes in a 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 SiP eliminates the requirement to mount a position sensor IC on a PCB, thus reducing compo- nent count and system cost, and making for easier design and assembly into the end product.

The AS5171A provides an analog output, and the AS5171B provides a digital output, which may be programmed either as a PWM interface or as a SENT-compliant interface. The analog AS5170A and digital AS5170B ICs are housed in an 8-pin SOIC package. Like all magnetic position sensors from this vendor, the AS5170 and AS5171 benefit from stray magnetic field immunity, enabling unimpaired operation even in the presence of strong magnetic fields generated by electric motors, high current-carrying cables and other external devices.
This results in highly reliable performance and reduces system cost since there is no need for the shielding required by other magnetic position