Functionality

LPS001WP

10/30

Doc ID 18171 Rev 1

4

Functionality

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

bridge piezoresistors, whose output signal is converted by the IC interface.

Intrinsic mechanical stoppers prevent breakage in case of pressure overstress, ensuring

measurement repeatability.

The pressure inside the buried cavity under the membrane is constant and controlled by

process parameters.

To be compatible with traditional packaging technologies, a silicon holed cap is placed on

top of the sensing element. During the moulding phase, this opening is covered by

dedicated protection to avoid membrane blocking.

The package design leaves the holed cap exposed, allowing ambient pressure to reach the

sensing element.

4.2

IC interface

The complete measurement chain consists of a low-noise capacitive amplifier, which

converts the resistive unbalance of the MEMS sensor into an analog voltage signal, and of

an analog-to-digital converter, which translates the produced signal into a digital bitstream.

The converter is coupled with a dedicated reconstruction filter which removes the high

frequency components of the quantization noise and provides low rate and high resolution

digital words.

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.

Obsolete

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- Obsolete

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