Texas Instruments Universal EVM for Single/Dual OpAmps with Shutdown in MSOP/SOIC/SOT-23 Packages OPAMPEVM-SOT23SHDN OPAMPEVM-SOT23SHDN 데이터 시트
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OPAMPEVM-SOT23SHDN
Two Operational Amplifier Instrumentation Amplifier
4-8
Example Circuits
4.6
Two Operational Amplifier Instrumentation Amplifier
Figure 4–5 shows area 200 equipped with a dual operational amplifier config-
ured as a two-operational-amplifier instrumentation amplifier using a voltage
reference and single power supply.
ured 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
function for the circuit as shown is:
function for the circuit as shown is:
V
OUT
+
V
IN
ǒ
1
)
2
R206
R210
)
R206
R221
R221
Ǔ
)
VREF2
Where
R206 = R202 and R221 = R204
To cancel the effects of input bias current, set R208 = R206 || R210 and set
R211 = R202 ||R204, or use a 0-
R211 = R202 ||R204, or use a 0-
Ω
jumper for R208 and R211 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 R216 and R217 for the desired
VREF2 voltage. The formula for calculating VREF2 is:
provides a low impedance reference for the circuit at about 1/2 V2+ in a 3 V
system. Another option is to adjust resistors R216 and R217 for the desired
VREF2 voltage. The formula for calculating VREF2 is:
VREF2
+
1.24
V
ǒ
R216
)
R217
R217
Ǔ