Input Voltage (V)

0

0.5

1

1.5

0

0.025

0.05

0.1

Load

0.075

2

D001

21

OPA187, OPA2187, OPA4187

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SBOS807 – DECEMBER 2016

Product Folder Links: OPA187 OPA2187 OPA4187

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Typical Applications (continued)

8.2.1.1 Design Requirements

The design requirements are:

•

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

flows through the first stage of the design. The current gain from the first stage to the second stage is based on

This application benefits from an operational amplifier with low offset voltage, low temperature drift, and rail-to-

rail output. The OPAx187 CMOS operational amplifier is a high-precision, ultra-low offset, ultra-low drift amplifier,

optimized for wide-voltage, single-supply operation, with an output swing to within 5 mV of the positive rail. The

OPAx187 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 this device

appropriate for precise dc control. The rail-to-rail output stage of the OPAx187 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 reference design

TIPD102, a step-by-step process to design a High-Side Voltage-to-Current (V-I) Converter.

For step-by-step design procedure, circuit schematics, bill of materials, PCB files, simulation results, and test

results, refer to TI Precision Design TIPD102, High-Side Voltage-to-Current (V-I) Converter (SLAU502).

8.2.1.3 Application Curves

Figure 42 shows the measured transfer function for the high-side voltage-to-current converter shown in

Figure 41.

Figure 42. Measured Transfer Function for High-Side V-I Converter