Input Voltage (V)

0

0.5

1

1.5

0

0.025

0.05

0.1

Load

0.075

2

D001

12

OPA333-Q1

SBOS522A – JUNE 2010 – REVISED NOVEMBER 2019

www.ti.com

Product Folder Links: OPA333-Q1

Submit Documentation Feedback

Copyright © 2010–2019, Texas Instruments Incorporated

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, VIN, and the three

current sensing resistors, RS1, RS2, and RS3. The relationship between VIN and RS1 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 RS2 and RS3.

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-Q1 CMOS operational amplifier is a high-

precision, 5-µV 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-Q1 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-Q1 makes sure 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 the High-Side V-I

Converter reference design.

8.2.1.3 Application Curve

Figure 21. Measured Transfer Function for High-Side V-I Converter