Smartphone and wearables are about to get better at guiding and mapping, even where satellite navigation cannot work, using the latest electronic compass (eCompass) from STMicroelectronics.
Fitness-tracking smartphone apps, smartwatches and bands need continuous location data for mapping and recording. Accuracy is critical for wearers who like to monitor their progress and share achievements online. A built-in eCompass helps calculate location when satellite signals are unavailable, such as inside buildings or when running or cycling under tree cover. However, current solutions can give errors of about 10° in latitudes such as Northern Italy or Northern California. This can put the user off course by 150m or more in every kilometre travelled.
ST’s LSM303AGR eCompass cuts the heading error to less than 4°, leveraging the company’s proprietary technology for manufacturing high-accuracy magnetic sensors. This enhanced accuracy, combined with ultra-low-power operation consuming up to 50% less than competing devices when in low-power mode, is particularly well suited to high-precision Pedestrian Dead Reckoning (PDR) on mobile devices.
The LSM303AGR also enhances dead-reckoning accuracy in applications such as automotive navigation, and maintains accuracy over the full temperature range from -40 to +85°C, whereas competing devices can vary by as much as 35% or more over small intervals such as between normal room temperature and human-body temperature.
As an all-in-one eCompass IC fabricated on a single die, the LSM303AGR combines a 3-axis MEMS accelerometer leveraging ST’s proven ThELMA technology and a very compact 3-axis Anisotropic Magneto-Resistive (AMR) sensor that delivers higher sensitivity and lower noise than conventional Hall sensors. ST’s own AMR manufacturing process technology gives the LSM303AGR superior temperature stability compared to alternatives made using Giant Magneto-Resistive (GMR) or Tunnel Magneto-Resistive (TMR) technology. ST’s AMR sensor also has high dynamic range, which further contributes to the device’s accuracy by preventing magnetic saturation in areas of high ambient-field strength.
ST has tested the LSM303AGR’s magnetic-sensing accuracy at various latitudes and recorded superior accuracy and temperature stability over current eCompass ICs and pure magnetic sensors from competing manufacturers.
Andrea Onetti, Group Vice President and General Manager, MEMS Sensors Division, STMicroelectronics, commented: “The industry-leading technology behind ST’s new eCompass further extends our lead in MEMS sensing for positioning and motion detection in consumer devices. High-precision PDR, enabled by this device, will significantly enhance the user experience delivered by apps including fitness trackers and personal navigation on smartphones and devices like smart watches, which IHS predicts will exceed 100m units by 2020.”
ST’s LSM303AGR eCompass is available now, packaged as a 2x2x1mm 12-lead LGA, priced from $1.485 in 1,000 unit quantities.