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| OPA317-Q1 Datasheet, PDF (17/29 Pages) Texas Instruments – Zero-Drift, Low-Offset, Rail-to-Rail I/O Operational Amplifier | |||
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www.ti.com
OPA317-Q1, OPA2317-Q1, OPA4317-Q1
SLOS914 â JULY 2016
9.2 Typical Applications
The circuit shown in Figure 22 is a high-side voltage-to-current (V-I) converter. It translates an input voltage of
0 V to 2 V to an output current of 0 mA to 100 mA. Figure 23 shows the measured transfer function for this
circuit. The low offset voltage and offset drift of the OPA317 facilitate excellent DC accuracy for the circuit.
V+
VIN +
±
V+
+
A1
RS2
470
VRS2
IRS2
10 k R4
RS3
4.7
C7
2200 pF
IRS3
VRS3
R5
A2
+
330
Q2
200
Q1
R3
1000 pF
C6
10 k R2
RS1
2k
VRS1
IRS1
RLOAD
VLOAD
ILOAD
Copyright © 2016, Texas Instruments Incorporated
Figure 22. High-Side Voltage-to-Current (V-I) Converter
9.2.1 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
9.2.2 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.
Copyright © 2016, Texas Instruments Incorporated
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Product Folder Links: OPA317-Q1 OPA2317-Q1 OPA4317-Q1
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