OPA333 Datasheet, PDF (9/18 Pages) Burr-Brown (TI) – 1.8V, microPOWER CMOS OPERATIONAL AMPLIFIERS Zer-PI Drift Series

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Figure 4 shows the basic configuration for a bridge
amplifier.
A low-side current shunt monitor is shown in Figure 5. R_N
are operational resistors used to isolate the ADS1100 from
the noise of the digital I²C bus. Since the ADS1100 is a
16-bit converter, a precise reference is essential for
maximum accuracy. If absolute accuracy is not required,
and the 5V power supply is sufficiently stable, the
REF3130 may be omitted.
OPA333
OPA2333
SBOS351 − MARCH 2006
V_S
RR
RR
R₁
+5V
OPA333
V_OUT
R₁
V_REF
Figure 4. Single Op Amp Bridge Amplifier
3V
+5V
REF3130
Load
R₁
4.99kΩ
V
I_LOAD
R_SHUNT
1Ω
R₃
4.99kΩ
R₂
4.99kΩ
OPA333
R₄
48.7kΩ
R₆
71.5kΩ
R_N
56Ω
ADS1100
R_N
I²C
56Ω
Stray ground−loop reistance.
R₇
1.18kΩ
(PGA Gain = 4)
FS = 3.0V
1% resistors provide adequate common−mode rejection at small ground−loop errors.
Figure 5. Low-Side Current Monitor
9