ams: magnetic position sensors with ISO26262 compliance
ams announces a new series of magnetic position sensors with increased safety and diagnostic capabilities to help automotive OEMs achieve the highest in ISO26262 ASIL system safety-level compliance. The AS5270A/B devices are ideal for many automotive applications including brake and gas pedals, throttle valve and tumble flaps, steering wheel position, chassis ride-height, Exhaust Gas Recirculation (EGR) valves, fuel-level measurement systems, and 2/4 wheel drive switching.
The new AS5270A and AS5270B system-on-chip devices are 0 to 360o rotary magnetic position sensors, that provide contactless high resolution, absolute angle measurements. The AS5270A/B were developed as SEooC (Safety Element out of Context) devices, as defined per the ISO26262 functional safety standard specification. The AS5270A/B magnetic position sensors provide on-chip full datapath diagnostics, that test the entire device, from the Hall sensor front end, through the DSP engine that converts raw measurements of magnetic field strength into sine and cosine vectors, to the back-end interfaces and pins.
The AS5270A/B are stacked and aligned dual-die devices, AEC-Q100 Grade 0 qualified and come in MLF-16 surface mount packages for high-reliability and redundant operations. Separate package pins are provided for each die in order to avoid electrical fault in the device from affecting both dies. With an internal 14-bit (0.22o) resolution front-end core Hall sensor array, the AS5270A/B devices provide true 12-bit output resolution. The high sensitivity Hall sensor front-ends also enable the devices to work with small, lower cost target magnets and support a wide magnetic field strength input range of 10-90mT.
The AS5270A provides an analog output, and the AS5270B provides either a digital SENT (Single Edge Nibble Transmission) or PWM (Pulse Width Modulation) output that is customer programmable. Both devices also support customer programmable angular range limit clamps, digital filtering, and output linearization features. In addition, with the AS5270B there are customer programmable settings for various SENT and PWM interface protocol features. For both devices, one wire programming is accomplished via the output pin, and due to onboard charge-pumps no high voltage programming levels are required. Once the one-time-programmable (OTP) fuses are blown, there is no possibility of the devices becoming inadvertently or maliciously reprogrammed, thus further reducing automotive safety risks. The AS5270A/B position sensors operate off of a 5V supply voltage, and the supply and output pins are protected against overvoltage up to +20V. In addition, the supply pins are protected against reverse polarity up to –20V.
The AS5270A/B devices are immune to magnetic stray fields, thus ensuring highly accurate and repeatable measurements even in the nosiest of magnetic environments. This results in very reliable performance and reduced system cost, since there is no need for sophisticated shielding that is typically required by competitive magnetic position sensor ICs. The AS5270A/B magnetic position sensors are available immediately in production volumes.