Hi all,

A colleague of mine is looking at using a membrane strip potentiometer
as a touch sensor. This is a three-terminal device, just like a
typical pot, except that the wiper is only connected when pressure is
applied. In effect, the wiper is actually whatever point or points of
contact are made between the top foil layer and the bottom resistive
layer.

We were both puzzled to discover that the datasheet for this part
lists both a max and a MIN voltage. Max voltage is obvious for thermal
reasons. However, we are not sure why a minimum voltage is listed.
They list their standard product as rated from 5V to 30V and then they
state that custom products can be made with ratings ranging from 1V to
60V. This seems to indicate that the 5V lower spec is not simply a
typical value listed for convenience but that there would really be
some undesirable condition to using a lower voltage.

My colleague would like to run this at 3.3V since that is the system
voltage in his device. Does anyone here have any idea why there would
be a minimum voltage spec and what the impact of operating this device
at 3.3V (when 5V is the minimum rating) would be? The only idea I was
able to come up with is that perhaps there is a certain amount of
voltage noise present due to operation of the part and that 5V is the
lowest voltage at which the accuracy specs would not be affected by
the ratio of the supply voltage to the voltage noise.

Sean
--=20
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