SX Series
Pressure sensors
7/10
July 2008 / 052
www.sensortechnics.com
Table III. For 0 to 70°C operation
SPAN
VS
VB
R2
R1
FS
R5
Rp
5V
3.5V
9.09k
118
Ω
3V
604
Ω
2k
6V
4.5V
8.45k
86.6
Ω
4V
604
Ω
2k
9V
7V
7.87k
54.9
Ω
5V
1k
2k
12V
10V
7.15k
36.5
Ω
5V
1.82k
5k
12V
10V
7.15k
36.5
Ω
10V
511
Ω
2k
15V
12V
7.68k
31.6
Ω
5V
1.4k
5k
15V
12V
8.87k
31.6
Ω
10V
604
Ω
2k
APPLICATION INFORMATION (cont.)
(b) Remove the short and adjust the
500
Ω offset adjust pot until Vx is
again equal to VR.
(c) Adjust the 2k reference (VR) adjust
pot to get an output voltage (VO)
equal to 1.00V.
2. Apply the fuII-scale pressure and adjust
the span adjust pot, R5, to get the output
voltage that is desired to represent full-
scale.
Note: Application information shown here is based on the closed bridge configuration.
The choice of the operational amplifiers to
use is based on individual cost/performance
trade-offs. The accuracy will be primarily
limited by the amplifier’s common-mode
rejection, offset voltage drift with tempera-
ture and noise performance. Low cost, low
performance devices, such as the LM324
can be used if the temperature ranges
limited to 25°C +15°C and an accuracy of
+2% is adequate.
For more precise applications amplifiers
such as the LT1014 and LT1002 have been
found to be excellent.
An amplifier that uses a single supply is
shown in Figure V. Table III gives resistor
values for various supply and full-scale
output combinations.
Factory compensated devices
This application note provides the neces-
sary information for temperature compen-
sating and calibrating the SX sensors. In
some case, the customer may find that SX
devices which have been factory adjusted
for temperature compensation and span are
more economical for a particular application.
SenSym does offer devices with this feature.
For more information on these factory
calibrated and compensated devices, the
SCX series and SDX series, please contact
Sensortechnics.
Figure V: Button Sensor Amplifier Circuit
A =
LT1014CN
V
O = 4 [1 +
] V
IN + VR
B =
LM10CN
Resistors labled R
3 are 5-Element Resistor Arrays 10 kΩ. Two required
10k
R
G
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