OPA333_17 Datasheet, PDF (16/42 Pages) Texas Instruments – 1.8-V, microPower, CMOS Operational Amplifiers, Zero-Drift Series

OPA333, OPA2333
SBOS351E – MARCH 2006 – REVISED DECEMBER 2015
www.ti.com
Typical Applications (continued)
8.2.1.1 Design Requirements
The design requirements are as follows:
• Supply Voltage: 5 V DC
• Input: 0 V to 2 V DC
• Output: 0 mA to 100 mA DC
8.2.1.2 Detailed Design Procedure
The V-I transfer function of the circuit is based on the relationship between the input voltage, V_IN, and the three
current sensing resistors, R_S1, R_S2, and R_S3. The relationship between V_IN and R_S1 determines the current that
flows through the first stage of the design. The current gain from the first stage to the second stage is based on
the relationship between R_S2 and R_S3.
For a successful design, pay close attention to the dc characteristics of the operational amplifier chosen for the
application. To meet the performance goals, this application benefits from an operational amplifier with low offset
voltage, low temperature drift, and rail-to-rail output. The OPA2333 CMOS operational amplifier is a high-
precision, 5-uV offset, 0.05-μV/°C drift amplifier optimized for low-voltage, single-supply operation with an output
swing to within 50 mV of the positive rail. The OPA2333 family uses chopping techniques to provide low initial
offset voltage and near-zero drift over time and temperature. Low offset voltage and low drift reduce the offset
error in the system, making these devices appropriate for precise dc control. The rail-to-rail output stage of the
OPA2333 ensures that the output swing of the operational amplifier is able to fully control the gate of the
MOSFET devices within the supply rails.
A detailed error analysis, design procedure, and additional measured results are given in TIPD102.
8.2.1.3 Application Curve
0.1
Load
0.075
0.05
0.025
0
0
0.5
1
1.5
2
Input Voltage (V)
D001
Figure 21. Measured Transfer Function for High-Side V-I Converter
16
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