SX - Series
PRESSURE SENSORS
March 1998/052
Aubinger Weg 27, 82178 Puchheim, Germany
Phone 0049 - (0) 89 80 08 30, Fax 0049 - (0) 89 8 00 83 33
http://www.sensortechnics.com
Button Sensor Element
The button sensor element was de-
signed to allow easy interface with
additional cases and housings which then
allow pressure connection. The device can
be mounted with an o-ring, gasket, or RTV
seals on one or both sides of the device.
The device can then be glued or clamped
into a variety of fixtures and the leads can
be bent as necessary to allow for ease of
electrical connection. However, caution is
advised as repeated bending of the leads
will cause eventual breakage.
For most gage applications, pressure
should be applied to the top side of the
device. (See Physical Construction
Drawing.) For differential applications, the
top side of the device (P1) should be used
as the high pressure port and the bottom
(P2) as the low pressure port (except for
SX7300D, where P2 is the high pressure
port).
The button SX package has a very small
internal volume of 0.06 cubic centimeters
for P1 and 0.001 cubic centimeters for P2.
“N” Packaged Sensor
The "N” packaged sensor is designed for
convenient pressure connection and easy
PC board mounting. To mount the device
horizontally to a PC board, the leads can be
bent downward and the package attached
to the board using either tie wraps or moun-
MECHANICAL AND MOUNTING CONSIDERATIONS
ting screws. For pressure attachment,
tygon or silicon tubing is recommended.
The “N” package version of the sensor has
two (2) tubes available for pressure
connection. For gage devices, pressure
should be applied to port P1. For differential
pressure applications, port P1 should be
used as the high pressure port and P2
should be used as the low pressure port.
TO Package
The TO package parts are available with
pressure access only to P1 for absolute
and gauge pressure. Therefore, on gauge
devices the bottom of the TO package must
be left open so atmosphere.
Typically, tubing is attached directly around
the top of the TO can or the package can
be glued or O-ring sealed into a fixture. As
always care should be taken not to stress
the package.
For all sensor packages care should be
taken not so expose the parts to caustic
media. This includes washers for board
cleaning, etc..
GENERAL DISCUSSION
Output Characteristics
The SX Series devices give a voltage
output which is directly proportional to
applied pressure. The devices will give an
increase in positive going output when
increasing pressure is applied to pressure
port P1 of the device. If the devices are
operated in the backward gage mode, the
output will increase with decreases in
pressure. The devices are ratiometric to
the supply voltage. Changes in supply
voltage will cause proportional changes in
the offset voltage and full-scale span.
User Calibration
SX Series devices feature the button IC
pressure sensor element. This will keep
overall system costs down by allowing the
user to select calibration and temperature
compensation circuits which specifically
match individual application needs. In most
cases, the primary signal conditioning
elements to be added so the SX by the
user are: offset and span calibration and
temperature compensation.
Some typical circuits are shown in the
application section.
Vacuum Reference
(Absolute Devices)
Absolute sensors have a hermetically
sealed vacuum reference chamber. The
offset voltage on these units is therefore
measured at vacuum, 0 psia. Since all
pressure is measured relative to a vacuum
reference, all changes in barometric
pressure or changes in altitude will cause
changes in the device output.
Media Compatibility
SX devices are compatible with most non-
corrosive gases. Because the circuitry is
coated with a protective silicon gel
(parylene coating for all TO can devices),
some otherwise corrosive environments
can be compatible with the sensors. As
shown in the physical construction diagram
below for the button sensor element and
,,N” package, fluids must generally be
compatible with silicon gel, RTV, plastic, and
aluminum for forward gage use and RTV,
Silicon, glass and aluminum for backward
gage or differential applications. For
questions concerning media compatibility,
contact the factory.
Physical Construction