OPA388_17 Datasheet, PDF (21/34 Pages) Texas Instruments – Precision, Zero-Drift, Zero-Crossover, True Rail-to-Rail Input/Output, Operational Amplifiers

www.ti.com
OPA388, OPA2388, OPA4388
SBOS777 – DECEMBER 2016
System Examples (continued)
8.3.2 Precision, Low-Noise, DAC Buffer
The OPA388 can be used for a precision DAC buffer, as shown in Figure 44, in conjunction with the DAC8830.
The OPA388 provides an ultra-low drift, precision output buffer for the DAC. A wide range of DAC codes can be
used in the linear region because the OPA388 employs zero-crossover technology. A precise reference is
essential for maximum accuracy because the DAC8830 is a 16-bit converter.
VDD VREF
RFB
INV
±
OPA388
Serial Interface
DAC8830
VOUT
+
DGND
AGND
Copyright © 2016, Texas Instruments Incorporated
Figure 44. Precision DAC Buffer
8.3.3 Load Cell Measurement
Figure 45 shows the OPA388 in a high-CMRR dual-op amp instrumentation amplifier with a trim resistor and 6-
wire load cell for precision measurement. Figure 46 illustrates the output voltage as a function of load cell
resistance change, along with the nonlinearity of the system.
RG
VOUT
R2
10 k
GND
R4
R3
25 k
+5V
100 k
REF5025
R4
100 k
+5V
±
OPA388
+
GND
+5V
+SENSE
-SENSE
GND
Load Cell
R2
25 k
+5V
±
OPA388
+
GND
NŸ
G=5+
R_G
Figure 45. Load Cell Measurement Schematic
Copyright © 2016, Texas Instruments Incorporated
Submit Documentation Feedback
21
Product Folder Links: OPA388 OPA2388 OPA4388