CN108776505B - High-precision adjustable current source circuit - Google Patents
High-precision adjustable current source circuit Download PDFInfo
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- CN108776505B CN108776505B CN201810605190.8A CN201810605190A CN108776505B CN 108776505 B CN108776505 B CN 108776505B CN 201810605190 A CN201810605190 A CN 201810605190A CN 108776505 B CN108776505 B CN 108776505B
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- operational amplifier
- resistor
- inverting input
- voltage source
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/575—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices characterised by the feedback circuit
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- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Automation & Control Theory (AREA)
- Amplifiers (AREA)
- Control Of Electrical Variables (AREA)
- Control Of Voltage And Current In General (AREA)
Abstract
The invention relates to a high-precision adjustable current source circuit, which comprises a program-controlled voltage source unit, a first operational amplifier, a second operational amplifier and an MCU unit, wherein the program-controlled voltage source unit is connected with the first operational amplifier; the non-inverting input end of the first operational amplifier is connected with the non-inverting input end of the second operational amplifier through a buffer resistor; one end of the program control voltage source unit is connected with the MCU unit, and the other end of the program control voltage source unit is connected with the non-inverting input ends of the first operational amplifier and the second operational amplifier through buffer resistors respectively; the reverse input end of the first operational amplifier is connected with the output end and then is connected with the reverse input end of the second operational amplifier; the output end of the second operational amplifier is connected with the MCU. According to the invention, the voltage at two ends of the fifth resistor Rs is detected by the MCU unit and used as the output of the feedback regulation voltage source, so that the high-stability and high-precision output of the constant current source is realized, the detection and control voltage source of the MCU unit can realize the adjustability of the current source, and the circuit design greatly reduces the complexity of the source meter.
Description
Technical Field
The invention relates to the field of instruments and meters and electronic measurement, in particular to a high-precision adjustable current source circuit which can be applied to a high-precision source meter.
Background
The high-precision adjustable current source is one of the most common devices in the electronic measurement industry, and is widely used in industry and laboratories.
In the conventional source meter design, a voltage source and a current source are usually two independent modules, the circuit structure is complex, and the manufacturing cost of a PCB is high. In many current source designs, a voltage regulator tube and a triode are mainly used as implementation modes, voltage fluctuation easily affects reference output of a diode, a base electrode of the triode has tiny current inflow, and the factors affect the stability and the precision of a constant current source.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the high-precision adjustable current source circuit is simple in circuit design, low in cost and capable of generating a high-precision and high-stability constant current source.
The technical scheme adopted by the invention for solving the technical problems is as follows: a high-precision adjustable current source circuit comprises a program-controlled voltage source unit, a first operational amplifier, a second operational amplifier and an MCU unit; the non-inverting input end of the first operational amplifier is connected with the non-inverting input end of the second operational amplifier through a buffer resistor; one end of the program control voltage source unit is connected with the MCU unit, and the other end of the program control voltage source unit is connected with the non-inverting input ends of the first operational amplifier and the second operational amplifier through buffer resistors respectively; the inverting input end of the first operational amplifier is connected with the output end and then connected with the inverting input end of the second operational amplifier; and the output end of the second operational amplifier is connected with the MCU.
Furthermore, the buffer resistor of the present invention includes a first resistor and a second resistor; one end of the first resistor is connected with the non-inverting input end of the first operational amplifier, and the other end of the first resistor is connected with one end of the sampling resistor; one end of the second resistor is connected with the non-inverting input end of the second operational amplifier, and the other end of the second resistor is connected with the other end of the sampling resistor.
Still further, the inverting input terminal of the second operational amplifier of the present invention is provided with a third resistor, and a fourth resistor is disposed between the inverting input terminal and the output terminal; the second operational amplifier, the third resistor and the fourth resistor form a proportional amplification circuit.
The invention has the advantages that the defects in the background technology are overcome, the voltage at two ends of the fifth resistor Rs is detected by the MCU unit to be used as the output of the feedback regulation voltage source, so that the high-stability and high-precision output of the constant current source is realized, the detection and control voltage source of the MCU unit can realize the adjustment of the current source, and the circuit design greatly reduces the complexity of the source meter.
Drawings
The invention is further illustrated with reference to the following figures and examples.
Fig. 1 is a circuit schematic of the present invention.
Detailed Description
The invention will now be described in further detail with reference to the drawings and preferred embodiments. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
As shown in fig. 1, the high-precision adjustable current source circuit includes a program-controlled voltage source unit, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor Rs, a first operational amplifier U1A, a second operational amplifier U1B, and an MCU unit.
One end of the program control voltage source unit is connected with the MCU unit, and the other end of the program control voltage source unit is connected with one end of the first resistor R1 and one end of the fifth resistor Rs. The other end of the first resistor R1 is connected with the third pin of the first operational amplifier U1A. The second pin of the first operational amplifier U1A is connected to the first pin and a third resistor R3. The other end of the third resistor R3 is connected with the fourth resistor R4 and the sixth pin of the second operational amplifier U1B. The other end of the fourth resistor R4 is connected with the seventh pin of the second operational amplifier U1B and the MCU unit. The fifth pin of the second operational amplifier U1B is connected to one end of a second resistor R2. The other end of the second resistor R2 is connected to the other end of the fifth resistor Rs.
The principle of the present embodiment is explained:
controlling the output of the voltage source if the set constant current output Iout
Vout＝Iout*Rs
And the fifth resistor Rs is used as a sampling resistor, the voltage at two ends of the fifth resistor is sampled according to the constant current output requirement, and the output of the voltage source is fed back and regulated, so that the current can be constantly output.
The first resistor R1 and the second resistor R2 function as buffer resistors and function as a protection circuit.
The first operational amplifier U1A plays a following role, and no current flows out, so that the stability of a preceding stage output circuit can be ensured.
The third resistor R3, the fourth resistor R4 and the second operational amplifier U1B jointly form a proportional amplification circuit, the partial circuit carries out certain processing on the voltage difference between two ends of the sampling resistor and then sends the voltage difference to the MCU unit for processing and analysis, so that the voltage output is regulated in real time, and the high stability and high precision of the constant current source are guaranteed.
While particular embodiments of the present invention have been described in the foregoing specification, various modifications and alterations to the previously described embodiments will become apparent to those skilled in the art from this description without departing from the spirit and scope of the invention.
Claims (1)
1. The utility model provides a high accuracy adjustable current source circuit which characterized in that: the system comprises a program-controlled voltage source unit, a first operational amplifier, a second operational amplifier and an MCU unit; the non-inverting input end of the first operational amplifier is connected with the non-inverting input end of the second operational amplifier through a buffer resistor; one end of the program control voltage source unit is connected with the MCU unit, and the other end of the program control voltage source unit is connected with the non-inverting input ends of the first operational amplifier and the second operational amplifier through buffer resistors respectively; the inverting input end of the first operational amplifier is connected with the output end and then connected with the inverting input end of the second operational amplifier; the output end of the second operational amplifier is connected with the MCU;
the buffer resistor comprises a first resistor and a second resistor; one end of the first resistor is connected with the non-inverting input end of the first operational amplifier, and the other end of the first resistor is connected with one end of the sampling resistor; one end of the second resistor is connected with the non-inverting input end of the second operational amplifier, and the other end of the second resistor is connected with the other end of the sampling resistor;
a third resistor is arranged at the reverse input end of the second operational amplifier, and a fourth resistor is arranged between the reverse input end and the output end; the second operational amplifier, the third resistor and the fourth resistor form a proportional amplification circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810605190.8A CN108776505B (en) | 2018-06-13 | 2018-06-13 | High-precision adjustable current source circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810605190.8A CN108776505B (en) | 2018-06-13 | 2018-06-13 | High-precision adjustable current source circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108776505A CN108776505A (en) | 2018-11-09 |
| CN108776505B true CN108776505B (en) | 2020-07-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810605190.8A Active CN108776505B (en) | 2018-06-13 | 2018-06-13 | High-precision adjustable current source circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN108776505B (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102901845B (en) * | 2012-10-24 | 2013-12-11 | 华东光电集成器件研究所 | Zero compensation testing device of piezoresistive acceleration sensor |
| CN203552115U (en) * | 2013-10-30 | 2014-04-16 | 中国航空工业集团公司第六三一研究所 | Output circuit of program-control current source |
| CN104345764A (en) * | 2014-11-07 | 2015-02-11 | 绵阳市维博电子有限责任公司 | Constant-flow source |
| CN205388724U (en) * | 2015-12-24 | 2016-07-20 | 上海复弘科技发展有限公司 | Constant current source circuit |
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2018
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| Publication number | Publication date |
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| CN108776505A (en) | 2018-11-09 |
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