CN201707378U - High-accuracy linear isolating circuit based on common optical coupler - Google Patents
High-accuracy linear isolating circuit based on common optical coupler Download PDFInfo
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- CN201707378U CN201707378U CN2010202290858U CN201020229085U CN201707378U CN 201707378 U CN201707378 U CN 201707378U CN 2010202290858 U CN2010202290858 U CN 2010202290858U CN 201020229085 U CN201020229085 U CN 201020229085U CN 201707378 U CN201707378 U CN 201707378U
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Abstract
The utility model discloses a high-accuracy linear isolating circuit based on a common optical coupler, comprising a first-path photoelectric coupler (T1), a second-path photoelectric coupler (T2), a first operational amplifying circuit (IC1A) and a second operational amplifying circuit (IC1B), wherein the first-path photoelectric coupler (T1) is connected with the second-path photoelectric coupler (T2) in series; the second-path photoelectric coupler (T2) is connected with the first operational amplifying circuit (IC1A) in series; and the second operational amplifying circuit (IC1B) is connected with the second-path photoelectric coupler (T2) in parallel. Based on the negative feedback principle, the high-accuracy linear isolating circuit realizes high-accuracy linear isolating transmission on an analog signal by using the common two-path photoelectric couplers, and the circuit is simple and reliable, and has low cost and small occupied space; and the high-accuracy linear isolating circuit can be widely applied in electric isolation of input and output signals, and is especially applicable to miniaturized product design with more signals and independent return wires.
Description
Technical Field
The utility model relates to a circuit, especially a high accuracy linear isolation circuit based on ordinary opto-coupler belongs to and measures technical field.
Background
The photoelectric coupler consists of a light emitter and a light receiver, wherein the light emitter is a light emitting diode, the light receiver is a photosensitive triode, and the light emitter and the light receiver are sealed in the same tube shell. When the light receiver receives light, current output is generated. The electric signal uses light as transmission medium, so that it can implement good electric isolation of input and output signals, and has the advantages of small volume, long service life, no contact, anti-interference, isolation and quick response speed, etc. Further, the photoelectric coupler may be used to form a logic circuit such as an and gate, an or gate, or an nand gate. When the linear coupling of the photoelectric coupler is used for directly carrying out isolated transmission on an analog signal, due to the volt-ampere characteristic of a light emitting diode and a photosensitive triode in the photoelectric coupler, the linear region of the photoelectric coupler has nonlinear distortion to a certain degree actually, and the measurement requirement of high linearity cannot be met. Another solution for linear isolated transmission of analog signals is to use linear optocouplers. However, the linear optocoupler needs to be provided with an isolation power supply module at the front end and the rear end for power supply, and the design of a multi-signal miniaturized product with independent return wires cannot be realized.
Disclosure of Invention
The utility model aims to solve the technical problem that a high accuracy linear isolation circuit based on ordinary opto-coupler is provided, this circuit can realize that the high accuracy linear isolation transmission to analog signal and circuit are simple, reliable to overcome prior art not enough.
In order to solve the technical problem, the utility model discloses a technical scheme: high accuracy linear isolation circuit based on ordinary opto-coupler. The circuit comprises a first path of photoelectric coupler, a second path of photoelectric coupler, a first operational amplifier circuit and a second operational amplifier circuit, wherein the first path of photoelectric coupler is connected in series with the second path of photoelectric coupler, and the second path of photoelectric coupler is connected in series with the first operational amplifier circuit; the second operational amplifier circuit is connected with the second path of photoelectric coupler in parallel.
In the high-precision linear isolation circuit based on the common optocoupler, a collector of the first path of the optocoupler is connected with a collector of the second path of the optocoupler; and the emitter of the first path of photoelectric coupler is connected with the anode of the second operational amplifier circuit, and the emitter of the second path of photoelectric coupler is connected with the cathode of the second operational amplifier circuit.
In the high-precision linear isolation circuit based on the common optocoupler, the emitters of the first path of the optocoupler and the second path of the optocoupler are respectively connected in series with resistors.
In the high-precision linear isolation circuit based on the common optocoupler, an adjusting resistor is also connected in series between the two resistors connected in series with the emitters of the first path of the optocoupler and the second path of the optocoupler.
The utility model has the advantages that: the utility model discloses a double-circuit optoelectronic coupler and two fortune circuits of putting realize: firstly, an input signal is isolated and output through a first path of optical coupler, then the output of the first path of optical coupler is fed back to a second path of optical coupler for input, and through self-adaptive compensation of the two paths of optical couplers, nonlinearity of isolation transmission of a single path of optical coupler is compensated, so that linear isolation transmission of the input signal is realized. The utility model discloses through verifying many times, the nonlinearity is less than 1%, except that the opto-coupler requires to carry out the uniformity screening, other devices do not have special requirement. Because the diode has a conduction voltage below 2V, the linear isolation matching circuit is suitable for non-global linear isolation transmission of input signals larger than 2V. Compared with the prior art, the utility model discloses based on the negative feedback principle, realized the linear isolation transmission of high accuracy to analog signal through using ordinary double-circuit optoelectronic coupling device, the circuit is simple, reliable, low-priced, occupation space is little, but wide application in input/output signal's electric isolation, the specially adapted signal is many, the independent miniaturized product design of return wire.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
The present invention will be further described with reference to the accompanying drawings and the detailed description.
Detailed Description
Examples are given. As shown in fig. 1, the two-way optical coupler D1 includes a first way optical coupler T1 and a second way optical coupler T2, and the dual operational amplifier circuit includes a first operational amplifier circuit IC1A and a second operational amplifier circuit IC 1B. The first operational amplifier circuit IC1A adopts the emitter follower circuit to output signals, so as to meet the requirement of low impedance output, thereby reducing the influence on the interface circuit. The second operational amplifier circuit IC1B is a feedback link, and adjusts the current flowing through the diode in the second photocoupler T2 by using the feedback output by the first photocoupler T1, so that the steady-state currents of the two photocouplers are substantially equal, thereby compensating the nonlinearity of transmission by using the single photocoupler. The first path of photoelectric coupler T1 is connected in series with the second path of photoelectric coupler T2, and the second path of photoelectric coupler T2 is connected in series with the first operational amplifier circuit IC 1A; the second operational amplifier circuit IC1B is connected in parallel with the second output photocoupler T2. The collector electrode of the first path of photoelectric coupler T1 is connected with the collector electrode of the second path of photoelectric coupler T2; an emitter of the first path of photoelectric coupler T1 is connected with the anode of the second operational amplifier circuit IC1B, and an emitter of the second path of photoelectric coupler T2 is connected with the cathode of the second operational amplifier circuit IC 1B. A resistor R7 is connected in series with the emitter of the first photocoupler T1, a resistor R6 is connected in series with the emitter of the second photocoupler T2, and an adjusting resistor R1 is connected in series between the resistor R7 and the resistor R6. Resistor R6 and resistor R7 convert the transistor output current to a voltage for feedback input. The asymmetry of the resistor R6 and the resistor R7 is compensated by adjusting the resistor R1, so that the positive and negative voltage of the first operational amplifier circuit IC1A and the second operational amplifier circuit IC1B are equal.
The photoelectric coupler is a current type device, and the output voltage and the current are in direct proportion in a linear region. The first photocoupler T1 and the second photocoupler T2 are in the same device, so they have great consistency, and when the output voltages of the two emitters are equal, the currents flowing through the two diodes are equal. Therefore, there is a node current law at point a, and it can be found that:
. Setting the conduction voltage drop of a diode as
An input voltage of
Then, then
. And according to the 'virtual interruption' of the operational amplifier, the method can obtain
. Let the operational amplifier IC1A output a voltage of
Therefore, in summary, it can be obtained,
and finishing to obtain:
selecting
Is thus
. (formula 1)
Due to the fact that in the practical application,
andthe values are not completely equal, and therefore, when the design is performed by using the formula 1, errors of theoretical values and actual values are necessarily caused. The main factor of this error is
，
The larger the error. The following is given
、
、
、
、The selection principle is as follows:
1. the working current is selected according to the linear working area of the optical coupler, so that the working current is calculated
And。
2. determining resistance according to proportional relation of voltage input and output (formula 1)
The size of (2).
3. Selecting
。
Table 1 is a set of data actually tested.
TABLE 1 test data
In the experiment, TLP621-2 is used as the double-path optical coupler, and TL082ID is used as the operational amplifier. The equation for the calculated fit line is:
the nonlinearity was 0.67%. Wherein,
in order to output the fitting,
is input for fitting.
The embodiments of the present invention are not limited to the above embodiments, and various changes made without departing from the spirit and scope of the present invention are within the scope of the present invention.
Claims (4)
1. The utility model provides a high accuracy linear isolation circuit based on ordinary opto-coupler, includes first way photoelectric coupler (T1), second way photoelectric coupler (T2) and first operational amplifier circuit (IC 1A), second operational amplifier circuit (IC 1B), its characterized in that: the first path of photoelectric coupler (T1) is connected with the second path of photoelectric coupler (T2) in series, and the second path of photoelectric coupler (T2) is connected with the first operational amplifier circuit (IC 1A) in series; the second operational amplifier circuit (IC 1B) is connected in parallel with the second photo coupler (T2).
2. The high-precision linear isolation circuit based on the common optical coupler of claim 1, wherein: the collector electrode of the first path of photoelectric coupler (T1) is connected with the collector electrode of the second path of photoelectric coupler (T2); the emitter of the first path of photoelectric coupler (T1) is connected with the anode of the second operational amplifier circuit (IC 1B), and the emitter of the second path of photoelectric coupler (T2) is connected with the cathode of the second operational amplifier circuit (IC 1B).
3. The high-precision linear isolation circuit based on the common optical coupler as claimed in claim 2, wherein: and the emitters of the first path of photoelectric coupler (T1) and the second path of photoelectric coupler (T2) are respectively connected with resistors (R7 and R6) in series.
4. A high-precision linear isolation circuit based on a common optical coupler according to claim 3, characterized in that: and an adjusting resistor (R1) is connected in series between the two resistors (R7, R6) which are connected in series on the emitters of the first path photocoupler (T1) and the second path photocoupler (T2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202290858U CN201707378U (en) | 2010-06-18 | 2010-06-18 | High-accuracy linear isolating circuit based on common optical coupler |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202290858U CN201707378U (en) | 2010-06-18 | 2010-06-18 | High-accuracy linear isolating circuit based on common optical coupler |
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| Publication Number | Publication Date |
|---|---|
| CN201707378U true CN201707378U (en) | 2011-01-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010202290858U Expired - Fee Related CN201707378U (en) | 2010-06-18 | 2010-06-18 | High-accuracy linear isolating circuit based on common optical coupler |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107395191A (en) * | 2017-06-16 | 2017-11-24 | 薄焕林 | Passive linear optical coupling isolator |
| CN109471048A (en) * | 2018-12-29 | 2019-03-15 | 常熟开关制造有限公司(原常熟开关厂） | Low-cost electric pressure detection method and device, automatic change-over |
-
2010
- 2010-06-18 CN CN2010202290858U patent/CN201707378U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107395191A (en) * | 2017-06-16 | 2017-11-24 | 薄焕林 | Passive linear optical coupling isolator |
| CN109471048A (en) * | 2018-12-29 | 2019-03-15 | 常熟开关制造有限公司(原常熟开关厂） | Low-cost electric pressure detection method and device, automatic change-over |
| CN109471048B (en) * | 2018-12-29 | 2020-10-02 | 常熟开关制造有限公司(原常熟开关厂） | Low-cost voltage detection method and device and automatic transfer switch |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110112 Termination date: 20140618 |
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| EXPY | Termination of patent right or utility model |