Data Sheet

Functionality LPS25HB

14/50 DocID027112 Rev 4

3 Functionality

The LPS25HB is a high resolution, digital output pressure sensor packaged in an HLGA full-

mold package. The complete device includes a sensing element based on a piezoresistive

Wheatstone bridge approach, and an IC interface which communicates a digital signal from

the sensing element to the application.

3.1 Sensing element

An ST proprietary process is used to obtain a silicon membrane for MEMS pressure

sensors. When pressure is applied, the membrane deflection induces an imbalance in the

Wheatstone bridge piezoresistances whose output signal is converted by the IC interface.

3.2 I

C interface

The complete measurement chain is composed of a low-noise amplifier which converts the

resistance unbalance of the MEMS sensors (pressure and temperature) into an analog

voltage using an analog-to-digital converter.

The pressure and temperature data may be accessed through an I²C/SPI interface thus

making the device particularly suitable for direct interfacing with a microcontroller.

The LPS25HB features a Data-Ready signal which indicates when a new set of measured

pressure and temperature data are available, thus simplifying data synchronization in the

digital system that uses the device.

3.3 Factory calibration

The IC interface is factory calibrated at three temperatures and two pressures for sensitivity

and accuracy.

The trimming values are stored inside the device in a non-volatile structure. When the

device is turned on, the trimming parameters are downloaded into the registers to be

employed during normal operation which allows the device to be used without requiring any

further calibration.