CN202900260U - Constant flow source circuit - Google Patents
Constant flow source circuit Download PDFInfo
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- CN202900260U CN202900260U CN 201220611131 CN201220611131U CN202900260U CN 202900260 U CN202900260 U CN 202900260U CN 201220611131 CN201220611131 CN 201220611131 CN 201220611131 U CN201220611131 U CN 201220611131U CN 202900260 U CN202900260 U CN 202900260U
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Abstract
The utility model discloses a constant flow source circuit which comprises a reference power supply chip, an operational amplifier chip and first to fifth resistors. An input filter circuit is connected at an input end of the reference power supply chip, an output filter circuit is connected at an output end of the reference power supply chip, a fourth resistor R4 is connected between the output end of the reference power supply chip, and a positive input end of the operational amplifier chip, a second resistor R2 is connected between a negative input end of the operational amplifier chip, and an earth electrode, a first resistor R1 connected between the negative input end of the operational amplifier chip and the input end of the operational amplifier chip, a third R3 is connected between an output end of the operational amplifier chip and an output end, and a fifth resistor R5 is connected between the positive input end of the operational amplifier chip, and the output load. According to the constant flow source circuit, output accuracy and temperature stability are improved, performance demands of the wellbore diameter gauging and the like to the constant flow source can be met, and situations where the wellbore diameter gauging has higher demands for integration and temperature performance of the circuit are better applied to.
Description
Technical field
The utility model relates to power circuit, particularly a kind of constant-current source circuit.
Background technology
Caliper logging is must survey project in the oil well logging engineering.CAL has been described the continuous radial dimension of well, by CAL can reflect whether the well size meets the requirements, whether the phenomenon of caving in is arranged, whether during well logging has is hampered and meets card phenomenon etc.By the explanation of CAL, needed cement amount in the time of can estimating well cementation can be used as back-up curve simultaneously, verifies whether other logs exist unusually.Carry out at present the logger circuit of caliper logging, most constant-current source circuits that all utilize are measured, so the quality of constant-current source circuit performance directly has influence on caliper logging result's precision.
Constant-current source is that output current keeps constant current source, and desirable constant-current source should have following characteristics: do not change because the load output voltage changes; Do not change because of variation of ambient temperature; Internal resistance is infinitely great so that its electric current can all flow out to the outside.And in actual design and in using, can not guarantee the output current absolute stability of constant-current source, its reason that changes is many-sided, mainly contains following factor: due to 1 input voltage is unstable, power supply has the peak period that the low ebb phase is arranged, and impossible all-the-time stable as before; 2 are formed by load variations, and such as load short circuits, load current can be very large, and the output voltage of power supply can be tending towards close to zero, and time one is long also can to burn out power supply; 3 are facilitated by the condition of constant-current source own, bad such as the element quality that consists of constant-current source, and parameter changes or when entirely ineffective, just can not regulate well the fluctuation that front two kinds of conditions variation causes; 4 components and parts also can make constant-current source output unstable because the impact that is subjected to the environment such as temperature, humidity changes performance.
At present, circuit of three-terminal voltage-stabilizing integrated commonly used consists of constant-current source circuit, as shown in Figure 1, it has element and easily purchases, the characteristics such as circuit is simple, but at first the output voltage excursion of LM317 regulator block is larger, be generally 1.25V to 1.37V, all larger to constant-current source output accuracy and stability influence, next is that the LM317 regulator block has a minimum steady operation electric current, be generally 1.5mA, because the manufacturer of LM317 regulator block is different, model is different, and its minimum steady operation electric current is not identical yet, when the output current of LM317 regulator block during less than its minimum steady operation electric current, regulator block is with regard to cisco unity malfunction.Therefore, if when making constant-current source with the LM317 regulator block, do not note its minimum steady operation electric current, just may cause constant-current source work undesired.In addition, because the temperature performance of LM317 is not very good, when therefore especially using in oil well logging instrument, along with the increase of well depth, the rising of well temperature causes the output of constant-current source to change, and directly causes as a result generation deviation of caliper logging.
The utility model content
The utility model provides the constant-current source circuit of a kind of high output accuracy and stability for solving the technical problem that exists in the known technology.
The technical scheme that the utility model is taked for the technical problem that exists in the solution known technology is: a kind of constant-current source circuit, comprise a reference power supply chip, one operational amplifier chip and the first to the 5th resistance, the input of described reference power supply chip is connected to input filter circuit, the output of described reference power supply chip is connected to output filter circuit, be connected to the 4th resistance R 4 between the positive input terminal of the output of described reference power supply chip and described operational amplifier chip, be connected to the second resistance R 2 between the negative input end of described operational amplifier chip and the earthing pole, be connected to the first resistance R 1 between the negative input end of described operational amplifier chip and its output, be connected to the 3rd resistance R 3 between the output of described operational amplifier chip and the output loading, be connected to the 5th resistance R 5 between the positive input terminal of described operational amplifier chip and the output loading.
Described input filter circuit comprises the first capacitor C 1, and an end of described the first capacitor C 1 links to each other with the input of described reference power supply chip, and the other end links to each other with earthing pole.
Described output filter circuit comprises the second capacitor C 2, and an end of described the second capacitor C 2 links to each other with the output of described reference power supply chip, and the other end links to each other with earthing pole.
Described output filter circuit also comprises the 3rd electric capacity, and the capacitance of described the 3rd electric capacity is more than or equal to 10 times of the capacitance of the second capacitor C 2, and an end of described the 3rd electric capacity links to each other with the output of described reference power supply chip, and the other end links to each other with earthing pole.
Advantage and the good effect that the utlity model has are: for the weak point of the constant-current source that utilizes the LM317 modular design, adopted accurate reference power supply chip, operational amplifier and precision resister etc. form a kind of high-precision constant-current source, input stage is used the high precision reference power supply chip, it has low noise, high accuracy and low temperature drift performance, at the input of reference power supply chip 0.1 μ F electric capacity in parallel, can prevent that input supply voltage from can suddenly change, and reduction power supply noise, equally, but output representative value in parallel is any low-level noise voltage of 0.1 μ F filtering, can't affect device work; Output stage adopts operational amplifier and precision resister to form, can guarantee output impedance, enough temperature stabilities are arranged again, therefore can satisfy caliper logging etc. to the performance requirement of constant-current source circuit, no matter it is in the constant current output precision or on the temperature stabilization performance, all the constant-current source more designed than traditional Voltage stabilizing modules such as LM317 improves a lot, and more is applicable to this occasion that the integrated and temperature performance of circuit is all had higher requirements of oil well caliper logging.
Description of drawings
Fig. 1 is for adopting the constant-current source circuit schematic diagram of LM317 modular design;
Fig. 2 is circuit theory diagrams of the present utility model.
Among Fig. 2: U1, operational amplifier chip; U2, reference power supply chip; R1-R5, the first to the 5th resistance; C1-C2, the first to second electric capacity.
The specific embodiment
For further understanding summary of the invention of the present utility model, Characteristic, hereby exemplify following examples, and cooperate accompanying drawing to be described in detail as follows:
See also Fig. 2, a kind of constant-current source circuit, comprise a reference power supply chip, one operational amplifier chip and the first to the 5th resistance, the input of described reference power supply chip is connected to input filter circuit, the output of described reference power supply chip is connected to output filter circuit, be connected to the 4th resistance R 4 between the positive input terminal of the output of described reference power supply chip and described operational amplifier chip, be connected to the second resistance R 2 between the negative input end of described operational amplifier chip and the earthing pole, be connected to the first resistance R 1 between the negative input end of described operational amplifier chip and its output, be connected to the 3rd resistance R 3 between the output of described operational amplifier chip and the output loading, be connected to the 5th resistance R 5 between the positive input terminal of described operational amplifier chip and the output loading.
Described input filter circuit can comprise the first capacitor C 1, and an end of described the first capacitor C 1 links to each other with the input of described reference power supply chip, and the other end links to each other with earthing pole.
Described output filter circuit can comprise the second capacitor C 2, and an end of described the second capacitor C 2 links to each other with the output of described reference power supply chip, and the other end links to each other with earthing pole.
Described output filter circuit also can comprise the 3rd electric capacity, and the capacitance of described the 3rd electric capacity is more than or equal to 10 times of the capacitance of the second capacitor C 2, and an end of described the 3rd electric capacity links to each other with the output of described reference power supply chip, and the other end links to each other with earthing pole.
Reference power supply chip as input stage, choose the precision voltage reference chip that performance in the market surpasses LM317 voltage stabilizing chip, choose reference index and consider low noise, high accuracy and low temperature drift performance, Voltage-output changes very little in whole range of temperature, choose such reference power supply chip, for the constant current output of rear class provides a highly stable constant pressure source.Can change suddenly for preventing power supply at input, and reduce power supply noise, can 0.1 μ F electric capacity in parallel.Equally, but the output capacitance representative value is any low-level noise voltage of 0.1 μ F filtering, can't affect device work.In addition, the output capacitance of extra 1 μ F to 10 a μ F in parallel can be improved load transient response, and electric capacity serves as the stored energy source at this moment, can increase load current.When adding output capacitance, unique parameter that can descend is the opening time, and the latter is depended on the parameter of selected electric capacity.The output filter capacitor that also can equally only keep 0.1 a μ F at output.
In the constant current output level, the utility model adopts high performance operational amplifier and precision resister to form, reference index is: its existing extremely low offset voltage characteristic, has again low-down input bias current characteristic, different from the JFET amplifier, its low biasing and offset current be to the environment temperature relative insensitivity, though environment temperature up to 125 ℃, it is stable that this performance still keeps.This circuit utilizes the operational amplifier principle that void is short in the ideal situation, void is disconnected and designs, and reduces the impact that output current is subjected to load variations.Reference resistance adopts the millesimal metal foil resistor of precision, and temperature is floated low, temperature drift can be dropped to minimum to the output impact of constant-current source.
Adopt the design's specified 5.01mA constant-current source circuit, its temperature and load characteristic are as follows:
By above-mentioned experimental result as can be known, this constant-current source is its variations in temperature or load variations all is lower than 0.5% no matter, can satisfy the required precision of oil well caliper logging fully.
Although the above is described preferred embodiment of the present utility model by reference to the accompanying drawings; but the utility model is not limited to the above-mentioned specific embodiment; the above-mentioned specific embodiment only is schematic; be not restrictive; those of ordinary skill in the art is under enlightenment of the present utility model; not breaking away from the scope situation that the utility model aim and claim protect, can also make a lot of forms, these all belong within the protection domain of the present utility model.
Claims (4)
1. constant-current source circuit, it is characterized in that, comprise a reference power supply chip, one operational amplifier chip and the first to the 5th resistance, the input of described reference power supply chip is connected to input filter circuit, the output of described reference power supply chip is connected to output filter circuit, be connected to the 4th resistance (R4) between the positive input terminal of the output of described reference power supply chip and described operational amplifier chip, be connected to the second resistance (R2) between the negative input end of described operational amplifier chip and the earthing pole, be connected to the first resistance (R1) between the negative input end of described operational amplifier chip and its output, be connected to the 3rd resistance (R3) between the output of described operational amplifier chip and the output loading, be connected to the 5th resistance (R5) between the positive input terminal of described operational amplifier chip and the output loading.
2. constant-current source circuit according to claim 1 is characterized in that, described input filter circuit comprises the first electric capacity (C1), and an end of described the first electric capacity (C1) links to each other with the input of described reference power supply chip, and the other end links to each other with earthing pole.
3. constant-current source circuit according to claim 1 and 2 is characterized in that, described output filter circuit comprises the second electric capacity (C2), and an end of described the second electric capacity (C2) links to each other with the output of described reference power supply chip, and the other end links to each other with earthing pole.
4. constant-current source circuit according to claim 3, it is characterized in that, described output filter circuit also comprises the 3rd electric capacity, the capacitance of described the 3rd electric capacity is more than or equal to 10 times of the capacitance of the second electric capacity (C2), one end of described the 3rd electric capacity links to each other with the output of described reference power supply chip, and the other end links to each other with earthing pole.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220611131 CN202900260U (en) | 2012-11-16 | 2012-11-16 | Constant flow source circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220611131 CN202900260U (en) | 2012-11-16 | 2012-11-16 | Constant flow source circuit |
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| CN202900260U true CN202900260U (en) | 2013-04-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201220611131 Expired - Fee Related CN202900260U (en) | 2012-11-16 | 2012-11-16 | Constant flow source circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107203217A (en) * | 2017-07-26 | 2017-09-26 | 江苏科技大学 | A kind of underwater robot attitude regulation control system based on sliding formwork control |
| CN107450572A (en) * | 2017-07-26 | 2017-12-08 | 江苏科技大学 | Underwater robot attitude regulation control system and processing method based on sliding formwork control |
| CN109100052A (en) * | 2018-09-30 | 2018-12-28 | 深圳众城卓越科技有限公司 | A kind of detection circuit of PT100 temperature sensor |
-
2012
- 2012-11-16 CN CN 201220611131 patent/CN202900260U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107203217A (en) * | 2017-07-26 | 2017-09-26 | 江苏科技大学 | A kind of underwater robot attitude regulation control system based on sliding formwork control |
| CN107450572A (en) * | 2017-07-26 | 2017-12-08 | 江苏科技大学 | Underwater robot attitude regulation control system and processing method based on sliding formwork control |
| CN109100052A (en) * | 2018-09-30 | 2018-12-28 | 深圳众城卓越科技有限公司 | A kind of detection circuit of PT100 temperature sensor |
| CN109100052B (en) * | 2018-09-30 | 2024-03-12 | 深圳众城卓越科技有限公司 | PT100 temperature sensor's detection circuitry |
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Legal Events
| Date | Code | Title | Description |
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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: 20130424 Termination date: 20151116 |