Xtrinsic pressure sensor / altimeter

[Martin35804]

The relativelly new high-precision pressure sensor for altitude detection designed to help users further leverage advanced navigation capabilities and emerging location-based services such as GPS assist and e911. The Freescale Xtrinsic MPL3115A2 pressure sensor, based on micro-electromechanical systems (MEMS) technology, complements the accelerometers and magnetometers in the Xtrinsic portfolio to meet the growing demand for these types of components in smart mobile devices.

The Xtrinsic MPL3115A2 smart digital pressure sensor processes pressure and temperature data locally, requiring fewer computations assigned to the applications processor and thereby reducing power significantly compared to systems using basic sensors directly managed by the host processor. The pressure sensor features optimal efficiency with a FIFO (first-in/first-out) memory buffer, a standby mode of 2 micro amps and a low-power mode of 8.5 micro amps for current consumption savings depending on conditions of the processor and output data rates chosen.

The Xtrinsic MPL3115A2 pressure sensor is designed to address the increasing popularity of mobile location-based services used in sophisticated handsets by delivering 30 cm resolution, which enables the device to identify elevation at a granular level. For example, a phone could detect the exact floor a user is on within a high-rise building or a shopping mall, allowing location-based services to more accurately reflect immediate surroundings.

Beyond the smart mobile device market, the Xtrinsic MPL3115A2 pressure sensor has many other potential applications, including tracking assets in business and industrial settings, providing precise locations in emergency search and rescue missions, forecasting climate changes in desktop weather stations and monitoring home cooling and heating systems. In addition, the sensor is ideal for medical applications, including respiratory equipment and health monitoring and detection systems that can help identify the location of patients within their homes or other environments.

About the Xtrinsic MPL3115A2 pressure sensor

Freescale’s Xtrinsic MPL3115A2 pressure sensor offers advanced accuracy and sampling rates combined with low power consumption to increase performance. The device provides barometric and altimetry pressure detection up to 30 cm of resolution and delivers a digital output in either meters or pascals, based on user preference. The MPL3115A2 sensor also includes embedded functions and user-programmable options, such as temperature compensation, with variable sampling rates up to 128 Hz.

Smart features include autonomous data acquisition with two interruptions on thresholds detection. To enhance efficiency, the device regulates auto-wake and sleep modes (to avoid unnecessary use of power) and requires zero data processing for mobile devices and medical and security applications.

Freescale has a history of providing long-term production support for its products. The MPL3115A2 device is part of the Freescale Product Longevity program, with a minimum of 15 years of expected supply. See www.freescale.com/productlongevity for details, terms and conditions.

Availability, price and development support

Sample quantities of the Xtrinsic MPL3115A2 pressure sensor are available now from Freescale. Production quantities and samples are already available from Freescale and its distribution partners starting at a suggested resale price of $1.43 (USD) in 10,000-piece quantities.

The Freescale Sensor Toolbox offers hardware, software and accessories in a common platform for acceleration, magnetic, pressure and touch sensors.
In addition, the DEMOSTBMPL3115A2 includes the Xtrinsic MPL3115A2 pressure sensor development board and a USB board for a suggested resale price of $99 (USD).

Electrical specs for the MPL3115A2  pressure sensor include:

• Pressure Range:
  • Calibrated: 50 kPa to 110 kPa
  • Operational: 20 kPa to 110 kPa
• Equivalent Altitude Range:
  • Calibrated: 5574.4m down to -698.3m
  • Operational: 11774.9m down to -698.3m
• Temperature Range:  -40C to 85C
• Numerical Output Ranges:
  • Pressure: -131072 to +131071.75 Pa
  • Altitude: -32768m to 32767.9375m
  • Temperature: -128C to 127.9375C
• Supply Voltage:
  • 1.95V to 3.6V core
  • 1.6V to 3.6V I/O
• Supply Current at 1 Hz update rate:
  • 8.5 microamps (no oversampling)
  • 265 microamps (128X oversampling)
• Standby Current: 2 microamps
• 400 kHz I²C digital interface
• Resolution: 20 bit output field implies (2 X 131072 Pa / 2²⁰ bits) = 0.25 Pa/LSB
• Noise: 1.5 Pa RMS at 128X oversample rate

You may be wondering how the MPL3115A2 generates altitude estimates. It’s actually simple math:

Altitude = K1 X (1 – (P/P0)^K2) meters,

where

• K1 = 44300.77 meters
• K2 = 0.190263 (unitless)
• P0 = 101325 Pascals

http://www.engineeringtv.com/video/Freescale-Xtrinsic-MPL3115A2-Sm;Engineering-TV-Embedded-Videos