SLVU006A Datasheet, PDF (27/28 Pages) Texas Instruments – UNIVERSAL OPERATIONAL AMPLIFIER EVALUATION MODULE

Differential Amplifier
3.7 Differential Amplifier
Figure 3–6 shows area 300 equipped with a single operational amplifier
configured as a differential 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
R305
R307
VREF3
Where
+ ^{R305 R309}
R307 R308
The TLV431 adjustable precision shunt regulator, configured as shown,
provides a low impedance reference for the circuit at about 1/2 V3+ in a 3 V
system. Another option is to adjust resistors R315 and R316 for the desired
+ ǒ ⁾ Ǔ ^{VREF3 voltage. The formula for calculating VREF3 is:}
VREF3
1.24
V
R315 R316
R316
Figure 3–6. Single Operational Amplifier Differential Amplifier with Single Supply Using
Area 300
R318
C305
V3+
V3+
301–
GND3
V3–
C304
0.1 µF
C303
1 µF
C310
+
302–
Vin
– ³⁰³⁺
304+
Power Supply Bypass
V3–
V3+
R314
2.2 kΩ
VREF3 = 1.24 V
R306
R307
R308
R309
C312
R319
Jumper
R305
V3+
( ) Vout = Vin
R305
R307
+ VREF3
3 _{–5 4}
1 _{+ 2 U301}
3OUT
C311
V3–
R317
R305 ₌ R309
R307 R308
C306
R315
C
R
A
U302
TL431ACDBV5
R316
Jumper 304+ to VREF3
Voltage Reference
Example Circuits
3-9