Datasheet

Noninverting Amplifier
4-7
Example Circuits
4.5 Noninverting Amplifier
Figure 4–4 shows area 400 equipped with a single operational amplifier
configured as a noninverting amplifier with single-supply power input.
Basic setup is done by choice of input and feedback resistors. The transfer
function for the circuit as shown is:
V
OUT
V
IN
1
R 402
R 404
VREF 4
The input signal must be referenced to VREF4.
To cancel the effects of input bias current, set R409 = R402 || R404, or use a
0-Ω jumper for R409 if the operational amplifier is a low input bias operational
amplifier.
The TL431 adjustable precision shunt regulator, configured as shown,
provides a low impedance reference for the circuit at about 1/2 V4+ in a 3 V
system. Another option is to adjust resistors R410 and R411 for the desired
VREF4 voltage. The formula for calculating VREF4 is:
VREF 4 1.24 V
R 411 R 410
R 410
Figure 4–4. Noninverting Amplifier with Single Supply Using Area 400
C404 C403
C405
C406
V4+
V4–
V4+
GND4
V4–
Power Supply Bypass
+
–
6
1
2
3
4
V4+
V4–
R402
C402
R401
C401
R403
R404
R407
R408
R409
R406
C409
C408
4OUT
401–
402–
403+
404+
R411
C
R
A
U402 = TLV431ACDBV5
R410
Voltage Reference
U401
V4+
VREF4 = 1.24 V
R414
+
–
V
in
Jumper
0.1 µF 10 µF
Jumper
Jumper 402 – to VREF4
V
OUT
= V
IN
R405
R407
R409 = R402 II R404,
or Short if Using Low Input
Bias Op Amp
Input Signal With
Reference to VREF4
2.2 kΩ
()
+1 + VREF4
5
4/SD
4 FLT
R405
C407
C410
10 µF