SLVU006A Datasheet, PDF (25/28 Pages) Texas Instruments – UNIVERSAL OPERATIONAL AMPLIFIER EVALUATION MODULE

Two Operational Amplifier Instrumentation Amplifier
3.6 Two Operational Amplifier Instrumentation Amplifier
Figure 3–5 shows area 200 equipped with a dual operational amplifier
configured as a two-operational-amplifier instrumentation amplifier using a
voltage reference and single power supply.
Basic setup is done by choice of input and feedback resistors. The transfer
+ ǒ ) ) Ǔ ) ^{function for the circuit as shown is:}
VOUT
VIN 1
2R205
R207
R205
R206
VREF2
Where
R205 = R202
and
R206 = R204
To cancel the effects of input bias current, set R209 = R205 || R207 and set
R210 = R202 ||R204, or use a 0 Ω jumper for R209 and R210 if the operational
amplifier is a low input bias operational amplifier.
The TLV431 adjustable precision shunt regulator, configured as shown,
provides a low impedance reference for the circuit at about 1/2 V2+ in a 3 V
system. Another option is to adjust resistors R215 and R216 for the desired
+ ǒ ⁾ Ǔ ^{VREF2 voltage. The formula for calculating VREF2 is:}
VREF2
1.24
V
R215 R216
R216
Example Circuits
3-7