Magnetic position sensors excel in safety-critical automotive applications
ams has introduced a new family of magnetic rotary position sensors with advanced safety features for automotive applications requiring ISO26262 compliance.
Highly integrated systems-on-chip, all magnetic rotary position sensors from ams incorporate Hall magnetic sensing elements, an analog front end and digital signal processing to produce accurate and precise angle measurements. The new ‘60 Series sensors – the AS5161 and AS5261 (with a digital PWM output) and the AS5162 and AS5262 (with analog voltage output) – now also feature best-in-class automotive protection features that enable vehicle manufacturers to achieve ISO26262 compliance in safety-critical applications.
The rigorous ISO26262 standard for automotive functional safety requires vehicle manufacturers to achieve high levels of reliability, to analyze the effects of the failure modes of components and systems, and to take measures to guarantee functional safety in the event of a predictable failure.
The ‘60 Series sensors enable manufacturers to achieve ISO26262 compliance by offering very high reliability, comprehensive analysis of the effects of direct and indirect dangerous faults, and very low Failure In Time (FIT) rates. Dual stacked dice (single package) versions, which are fully redundant, the AS5261 and AS5262 sensors can be used in applications requiring the highest ASIL D safety grading.
ams has also enabled enhanced self-diagnostic capabilities in this new generation of automotive position sensors. For example, they can detect a failed input voltage, and the broken ground detection feature with pull-down resistor operates even at high temperatures, unlike in competitive products.
With this new generation of sensors, ams has also implemented a number of power-saving features, resulting in leading-edge efficiency. While the ‘60 Series devices typically draw a 10 mA supply current, many competitive devices draw more than 15 mA.
The 60 Series sensors will be used to sense angular displacement in a wide variety of automotive applications, including the accelerator pedal, brake pedal, chassis ride height monitor, HVAC valve position, and the steering wheel.
The devices are also well suited for use in transmission (2WD/4WD switch, gearshift actuator) and throttle (EGR, tumble flap, throttle position, turbo-charger) applications.
Unlike competitive magnetic sensors, the ‘60 Series sensors from ams require very few external components and can be used with a low-cost ferrite magnet. They also require no external shielding, since they are immune to stray magnetic fields due to ams’ proprietary differential-input technology. The devices are tolerant of magnet misalignment and of variances in the air gap from one unit to another. The ‘60 Series devices, therefore, offer vehicle manufacturers low bill-of-materials and assembly costs.
The precise ‘60 Series sensors measure angular displacement at 16,384 points per revolution. Integral non-linearity is 1.4° (maximum) over a complete revolution and across the operating temperature range (-40°C to 150°C).
All four devices offer a small propagation delay – the delay between the input from the sense magnet and the angle calculation output leaving the chip – of 300 µs. This means they are able to provide accurate position measurements even of rotors operating at high speed.
According to Bernd Gessner, vice-president and general manager of the automotive business unit at ams, “Automotive manufacturers are looking for high-tech position sensors that are reliable and predictable enough to be used in critical systems such as brake pedals and accelerator pedals. With the new ‘60 Series sensors, ams has given the industry the measurement performance they need in a device that is extremely robust and safe.”
Price & availability
The AS5161 and AS5162 magnetic position sensors are available in a small SOIC8 package. The stacked-dice (redundant) AS5261 and AS5262 are in an MLF16 package. The devices are available for sampling now. The AS5161 and AS5162 are priced at $3.43 for 1,000 pieces, and the AS5261 and AS5262 at $6.50.
An evaluation package for the ‘60 Series position sensors is available from ams, priced at $381. For further information on the devices or to request samples, please visit www.ams.com/eng/Products/Magnetic-Position-Sensors/Magnetic-Rotary-Position-Sensors .