ILPS28QSW Qvar data

[Jasper0180]

Good morning,

I want to use the ILPS28QSW to measure pressure and detect water.
I use the development board (STEVAL-MKI223V1K) to test the ILPS28QSW.
Measuring the pressure works perfectly.

I am currently working with Qvar, but i do not yet fully understand what result i should expect.
When I connect the STEVAL-MKE001A I get the following Qvar data:
LSB mV °C
-4423186 -10.38 21.55
-4480098 -10.52 21.55
-4587456 -10.77 21.56
-4570778 -10.73 21.56
-4558559 -10.70 21.55

What kind of data do I expect? Is the Qvar data correct?
In addition, water can be detected using Qvar if the sensor is assembled in a plastic housing??

[Federica Bossi · Accepted solution]

Hi @Jasper0180 ,

Welcome to ST Community!

For this Qvar feature, you can refer to the dedicated design tip: https://www.st.com/resource/en/design_tip/dt0153-qvar-for-waterleak-detection-stmicroelectronics.pdf

About the Qvar values, you should have an offset with noise if nothing is connected to Qvar input. When water creates a resistive path between an input and GND, the Qvar value should saturate (negative or positive depending on whether the Qvar input is positive or negative).

To use the water leakage feature, the electrode must be exposed to water. Therefore, if your application is embedded in a plastic case, two exposed pins must communicate with the environment through the plastic.