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FN6200.3
November 3, 2009
Strain Gauge
The strain gauge is an ideal application to take
advantage of the moderate bandwidth and high
accuracy of the ISL55001. The operation of the circuit
is very straightforward. As the strain variable
component resistor in the balanced bridge is subjected
to increasing strain, its resistance changes, resulting in
an imbalance in the bridge. A voltage variation from
the referenced high accuracy source is generated and
translated to the difference amplifier through the buffer
stage. This voltage difference as a function of the strain
is converted into an output voltage (see Figure
28).
+
-
V+
V-
V2
5V
C12
1nF
VOUT
(V1+V2+V3+V4)
RL
1kΩ
V4
5V
R17
1kΩ
C6
1nF
RF
1kΩ
+
-
R18
1kΩ
+
-
+
-
VARIABLE
SUBJECT TO
1kΩ
R15
R16
1kΩ
V5
0V
FIGURE 28. STRAIN GAUGE AMPLIFIER
ISL55001