Question
I would like to use some capacitive buttons (up to 8) in a shower control
system. The buttons will be inside the shower box. The customer, wet because
under shower, has to touch the buttons to interact with the system. Clearly is
an hard moisture environment. My question is if there are problems using this
kind of buttons with AD7148 or AD7143 and which is more suitable for the
application between this two components.
Answer
Like any capacitive sensor application, the sensors performance will be
affected by water and humidity. The AD714x internal environmental algorithms
will automatically track and correct for humidity conditions. Water conditions
(especially saturated) become more challenging and need to be evaluated
carefully for each application.
Here are some additional notes:
Water will effect a capacitance sensor, its just a matter of figuring out how
much effect the water will have, and whether it will stop the sensor from
working. As this is dependent to some extent on the size of the senor , and the
application, I highly recommend some testing in the application.
The AD7147 and AD7148, are more robust to the effects of water, so I'd
recommend you consider those parts for your design.