LPS001WP Datasheet, PDF (10/30 Pages) STMicroelectronics – MEMS pressure sensor 300-1100 mbar absolute digital output barometer

Functionality
4
Functionality
LPS001WP
The LPS001WP is a high-resolution, digital-output pressure sensor packaged in an LGA
holed package. The complete device includes a sensing element based on a piezoresistive
Whetstone bridge approach, and an IC interface capable of providing information from the
sensing element to external applications as a digital signal.
4.1
Sensing element
An ST proprietary process is used to obtain a mono-silicon µ-sized membrane for MEMS
pressure sensors, without requiring substrate-to-substrate bonding.
) _{When pressure is applied, membrane deflection induces an imbalance in the Wheatstone}
t(s ^{bridge piezoresistors, whose output signal is converted by the IC interface.}
c _{Intrinsic mechanical stoppers prevent breakage in case of pressure overstress, ensuring}
du ^{measurement repeatability.}
ro _{The pressure inside the buried cavity under the membrane is constant and controlled by}
P _{process parameters.}
te To be compatible with traditional packaging technologies, a silicon holed cap is placed on
le top of the sensing element. During the moulding phase, this opening is covered by
o _{dedicated protection to avoid membrane blocking.}
bs _{The package design leaves the holed cap exposed, allowing ambient pressure to reach the}
O sensing element.
t(s) ^{- 4.2}
IC interface
uc The complete measurement chain consists of a low-noise capacitive amplifier, which
d _{converts the resistive unbalance of the MEMS sensor into an analog voltage signal, and of}
ro an analog-to-digital converter, which translates the produced signal into a digital bitstream.
P _{The converter is coupled with a dedicated reconstruction filter which removes the high}
tefrequency components of the quantization noise and provides low rate and high resolution
le^{digital words.}
so ^{The pressure data can be accessed through an I2C/SPI interface, making the device}
Ob ^{particularly suitable for direct interfacing with a microcontroller.}
4.3
Factory calibration
The IC interface is factory-calibrated at two temperatures and two pressure levels for
sensitivity and accuracy.
The trimming values are stored inside the device using a non-volatile structure. Each time
the device is turned on, the trimming parameters are downloaded into the registers to be
employed during normal operation. This allows the user to employ the device without
requiring further calibration.
10/30
Doc ID 18171 Rev 1