Magnetic_Encoder_for_General_presentation.pdf

a leap ahead Magnetic Rotary Encoder IC’s Aug. 2009 22 Magnetic Rotary Encoder Basic’s Edwin Herbert Hall 1855 - 1938 I I I I A magnetic rotary encoder is an integrated circuit with built-in Hall elements. Hall elements can detect magnetic fields over the surface of the chip. With a proper arrangement of multiple Hall elements and digital signal processing, the chip can precisely detect the rotating angle of a magnet that is placed over the chip 33 The AMS patented principle ADC Digital Filter Frontend Amplifier Cos Sin DSP Angle Magnitude A group of 4 or 8 Hall Sensors is arranged in a circular array, embedded in the silicon chip. The circular array has a diameter of 2,2mm Opposite Hall Sensors are combined by differential amplification The Sin- and Cos- Signals are digitized by two parallel ADC‘s Subsequent digital filtering reduces noise The DSP converts Sine and Cosine signals into Angle and Magnitude (rectangular to polar coordinate transformation) Cos Sin N S Sin -Sin Cos -Cos Sin Cos Ma g φ 0 ° 90 ° 180 ° 270 ° 44 Magnetic Rotary Encoder – Benefits Key Features AS5xxx ? Resolution from 8 to 12 bit ? Automotive qualified to AEC-Q100 ? Single Die Dual Die solutions ? Two independet chips in one package ? For saftey critical applications ? 100% identical electrically isolated ? No loss of accuracy + centered magnet over both chip ? Different (combinations of) output formats (SSI, Analog, PWM, I2C, Incr., BLDC) ? Contactless ? No wear; High reliability; Insensitive to humidity, dust, dirt, etc.. ? Wide temperature range ?-40°C to +125°C, versions up to “+150°C” available ? No compensation or calibration required ?±0.5° initial accuracy ? Tolerant to unwanted external magnetic fields? Automatic compensation ? Complete “true-system-on-chip” ? Low power consumption ? typ. ~15mA (pulsed mode 1mA) ? Daisy Chain mode, Chip-ID Diagnostic features ? Zero position programming Multi turn counter ? Small thin pac