Accurate location of mobile devices will be the key enabler for many emerging Location-Based Services (LBS). The challenge is to provide the means of identifying the location of the mobile device in three dimensions in a way that meets a variety of conflicting constraints including spatial resolution, reliability, physical size, robustness, and cost.
The universally adopted GNSS (Global Navigation Satellite System) will allow the horizontal position (latitude and longitude) of the device to be calculated to within a metre in optimum conditions where the device can receive signals from four or more satellites.
For the third dimension (vertical elevation), atmospheric pressure can provide greater resolution than GNSS, especially when fewer than four satellite signals are visible as pressure drops steadily with increased elevation. ST’s new pressure sensor can accurately measure air pressure from 260 millibars, which is the typical air pressure at a height of around 10km, to 1260 millibars, which is the typical air pressure at 1,800m below sea-level with high accuracy.
ST’s LPS331AP pressure-sensing device is housed in a tiny 3x3mm package and offers low voltage operation and ultra-low power consumption, making it ideal for use in smart phones, sports watches, and other portable equipment, as well as in weather stations and automotive and industrial applications.
According to Benedetto Vigna, Executive Vice President, Analog, MEMS & Sensors Group, ST Microelectronics, since launching the Consumerization Wave of MEMS devices, the company has developed and delivered sensors able to detect gravity, acceleration, angular rate and the Earth’s magnetic field, all of which help smart consumer devices detect and react to motion.
The new pressure sensors from ST are capable of sensing the weight of the atmosphere and will help consumer products recognise if a person or an object is moving up or down.
Key features of ST’s LPS331AP pressure sensors:
- Fabricated on a monolithic silicon chip using a proprietary MEMS technology, VENSENS
- Technology provides high burst resistance, eliminates wafer-to-wafer bonding and maximises reliability
- Sensing element based on flexible silicon membrane formed above an air cavity with a controlled gap and defined internal pressure
- Small membrane, protected from breakage by built-in mechanical stoppers
- Piezoresistor embedded in the membrane
- High resolution, low-noise sensor can detect differences within cm of altitude variation
- Selectable ODR from 1 Hz to 25 Hz
- Low power consumption
- Low resolution mode: 5.5µA, high resolution mode: 30 µA
- Supply voltage: 1.71 to 3.6 V
- Operating temperature range extending from -40°C to +85°C
- Integrated temperature sensor enables temperature span compensation