CN103702471A - Constant-current circuit, charging circuit and LED driving circuit - Google Patents
Constant-current circuit, charging circuit and LED driving circuit Download PDFInfo
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- CN103702471A CN103702471A CN201210367326.9A CN201210367326A CN103702471A CN 103702471 A CN103702471 A CN 103702471A CN 201210367326 A CN201210367326 A CN 201210367326A CN 103702471 A CN103702471 A CN 103702471A
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Abstract
The invention discloses a constant-current circuit, which comprises an operational amplifier, a regulation and feedback unit and a voltage stabilizing unit, wherein the in-phase input end of the operational amplifier is connected to a working power supply through the voltage stabilizing unit, and is connected with the ground through a first resistor; the output end of the operational amplifier is connected with the regulation end of the regulation and feedback unit through a second resistor; the input end of the regulation and feedback unit is connected with a load through a third resistor, and the output end of the regulation and feedback unit is connected with the ground through a detection resistor; the input end of the regulation and feedback unit is also connected with the inverted input end of the operational amplifier; the regulation and feedback unit is used for regulating current flowing through the load according to the voltage output by the operational amplifier, and feeding back input end voltage to the inverted input end of the operational amplifier. In addition, the invention further discloses a charging circuit and an LED driving circuit, which both comprise the constant current circuit. The constant-current circuit, the charging circuit and the LED driving circuit are simple and low in cost.
Description
Technical field
The present invention relates to constant current control technology, particularly relate to a kind of constant-current circuit, a kind of charging circuit and a kind of LED drive circuit.
Background technology
In electronic circuit, sometimes need to carry out constant current control to guarantee the work of circuit.For example LED drive circuit, just need to export constant current so that LED normally works.In order to reach extraordinary constant current effect, traditional constant current is controlled and is conventionally all adopted constant current chip to realize.
Yet constant current chip is requiring not too high occasion to seem not too flexible to constant current, is first that constant current chip has specific specification, its electric current is determined, when circuit need to be used another constant current value work, need to change constant current chip.On the other hand, the cost component that constant current chip occupies in ball bearing made using is larger, with respect to whole circuit, does not calculate.Finally, constant current chip may also need MCU cooperation to carry out constant current control, relatively high for the requirement of circuit designer.
Summary of the invention
Based on this, be necessary to provide a kind of circuit simple, lower-cost constant-current circuit.
In addition, also provide a kind of charging circuit.
And provide a kind of LED drive circuit.
A constant-current circuit, comprises operational amplifier, regulates feedback unit and voltage regulation unit; The in-phase input end of described operational amplifier is connected to working power by described voltage regulation unit, and by the first grounding through resistance; The output of described operational amplifier connects the adjustable side of described adjusting feedback unit by the second resistance; The input of described adjusting feedback unit connects load by the 3rd resistance; The output of described adjusting feedback unit is by detecting grounding through resistance; The input of described adjusting feedback unit is also connected with the inverting input of described operational amplifier; Described adjusting feedback unit flows through the size of current of described load according to the voltage-regulation of operational amplifier output, and input terminal voltage is fed back to the inverting input of operational amplifier.
In an embodiment, described voltage regulation unit is voltage-stabiliser tube therein, and the positive pole of described voltage-stabiliser tube is connected with described in-phase input end, and negative pole is connected with described working power.
Therein in an embodiment, described adjusting feedback unit is positive-negative-positive compound transistor, described positive-negative-positive compound transistor comprises the first positive-negative-positive triode and the second positive-negative-positive triode, and the base stage of described the first positive-negative-positive triode is connected with described the second resistance as the adjustable side of described adjusting feedback unit; Output as described adjusting feedback unit after the collector electrode of the collector electrode of described the first positive-negative-positive triode and the second positive-negative-positive triode is connected is connected with described detection resistance; The emitter of described the second positive-negative-positive triode is connected with described the 3rd resistance as the input of described adjusting feedback unit, and the emitter of described the first positive-negative-positive triode is connected with the base stage of described the second positive-negative-positive triode.
In an embodiment, at least one in described the first resistance, the second resistance and detection resistance is adjustable resistance therein.
A charging circuit, comprises constant-current circuit, and described constant-current circuit comprises operational amplifier, regulates feedback unit and voltage regulation unit; The in-phase input end of described operational amplifier is connected to charge power supply by described voltage regulation unit, and by the first grounding through resistance; The output of described operational amplifier connects the adjustable side of described adjusting feedback unit by the second resistance; The input of described adjusting feedback unit connects rechargeable battery by the 3rd resistance; The output of described adjusting feedback unit is by detecting grounding through resistance; The input of described adjusting feedback unit is also connected with the inverting input of described operational amplifier; Described adjusting feedback unit flows through the electric current of described load according to the voltage-regulation of operational amplifier output, and input terminal voltage is fed back to the inverting input of operational amplifier.
In an embodiment, described voltage regulation unit is voltage-stabiliser tube therein, and the positive pole of described voltage-stabiliser tube is connected with described in-phase input end, and negative pole is connected with described working power.
Therein in an embodiment, described adjusting feedback unit is positive-negative-positive compound transistor, described positive-negative-positive compound transistor comprises the first positive-negative-positive triode and the second positive-negative-positive triode, and the base stage of described the first positive-negative-positive triode is connected with described the second resistance as the adjustable side of described adjusting feedback unit; Output as described adjusting feedback unit after the collector electrode of the collector electrode of described the first positive-negative-positive triode and the second positive-negative-positive triode is connected is connected with described detection resistance; The emitter of described the second positive-negative-positive triode is connected with described the 3rd resistance as the input of described adjusting feedback unit, and the emitter of described the first positive-negative-positive triode is connected with the base stage of described the second positive-negative-positive triode.
In an embodiment, described charge power supply is 5V therein, and described operational amplifier model is LM358, described voltage-stabiliser tube model is LM336, and described the first resistance is 510 Ω, and the second resistance is 1K Ω, the 3rd resistance is 3.3 Ω, and detecting resistance is 0.47 Ω.
In an embodiment, at least one in described the first resistance, the second resistance and detection resistance is adjustable resistance therein.
A LED drive circuit, comprises above-mentioned constant-current circuit.
Above-mentioned constant-current circuit, charging circuit and LED drive circuit, only adopt less basic components and parts can realize the constant current that precision is lower and control, and circuit is simple, cost is lower, is applicable to the less demanding occasion of constant current accuracy.
Accompanying drawing explanation
Fig. 1 is the constant-current circuit schematic diagram of an embodiment.
Embodiment
As shown in Figure 1, be the constant-current circuit schematic diagram of an embodiment.This constant-current circuit 10 comprises operational amplifier U1, regulates feedback unit 100 and voltage regulation unit 200.The in-phase input end of operational amplifier U1 is connected to working power Vin by voltage regulation unit 200, and by the first resistance R 1 ground connection.The output of operational amplifier U1 connects by the second resistance R 2 adjustable side 102 that regulates feedback unit 100.
Regulate the input 104 of feedback unit 100 to connect load by the 3rd resistance R 3, and regulate the input of feedback unit 100 to be also connected with the inverting input of operational amplifier U1.Regulate the output 106 of feedback unit 100 by detecting resistance R sense ground connection.
Regulate feedback unit 100 according to the voltage-regulation of operational amplifier U1 output, to flow through the size of current of described load, and by the Voltage Feedback of input 104 inverting input to operational amplifier U1.At whole constant-current circuit during in steady-working state, operating voltage Vin by load, the 3rd resistance R 3, regulate feedback unit 100 and detect resistance R sense and form loop, current constant.
When changing appears in operating voltage Vin, first this variation is embodied in the in-phase input end of operational amplifier U1, and the voltage after operation amplifier makes to regulate feedback unit 100 to regulate accordingly, is specially, when operating voltage Vin becomes large, regulate the electric current that flows through load to reduce; When operating voltage Vin diminishes, regulate the electric current that flows through load to increase.
Simultaneously due to flow through load electric current increase or reduce, the voltage that is fed back to the inverting input of operational amplifier U1 by the input 104 that regulates feedback unit 100 presents corresponding variation,, when flowing through the electric current of load and reduce, the voltage of feedback increases, when flowing through the electric current increase of load, the voltage of feedback reduces.
After overregulating the adjustment repeatedly of feedback unit 100, circuit tends towards stability, by the current constant of load.
As shown in Figure 1, in specific embodiment, regulating feedback unit 100 is positive-negative-positive compound transistor, and this positive-negative-positive compound transistor comprises the first positive-negative-positive triode Q1 and the second positive-negative-positive triode Q2.The base stage of the first positive-negative-positive triode Q1 is as regulating the adjustable side 102 of feedback unit 100 to be connected with the second resistance R 2.Output 106 as adjusting feedback unit 100 after the collector electrode of the collector electrode of the first positive-negative-positive triode Q1 and the second positive-negative-positive triode Q2 is connected is connected with detection resistance R sense.The emitter of the second positive-negative-positive triode Q2 is as regulating the input 104 of feedback unit 100 to be connected with the 3rd resistance R 3, and the emitter of the first positive-negative-positive triode Q1 is connected with the base stage of the second positive-negative-positive triode Q2.
Based on this specific embodiment, the operation principle of constant-current circuit 10 is described as follows.
When operating voltage Vin becomes large, through the constant pressure drop of constant voltage-stabiliser tube ZD1, the voltage that arrives the in-phase input end of operational amplifier U1 increases with respect to original voltage, therefore through after operation amplifier, it is large that operational amplifier U1 output end voltage becomes, this voltage reduces the Veb driving voltage of positive-negative-positive compound transistor, thereby the conducting of described positive-negative-positive compound transistor diminishes, and the electric current that flows through load diminishes, therefore the voltage of output 104 increases, feed back to after operational amplifier U1, the voltage of operational amplifier U1 output reduces again before comparing, this voltage increases the Veb driving voltage of positive-negative-positive compound transistor, it is large that thereby the conducting of described positive-negative-positive compound transistor becomes, and the electric current that flows through load becomes large, therefore the voltage of output 104 reduces, so repeatedly adjust, circuit finally can tend towards stability, with constant current work.
When operating voltage Vin reduces, based on similar principle, circuit finally also can tend towards stability, with constant current work.
In a preferred embodiment, at least one in the first resistance R 1, the second resistance R 2 and detection resistance R sense is adjustable resistance.By adjusting the first resistance R 1, the second resistance R 2 and detecting the constant current value that resistance R sense can change whole constant-current circuit, make circuit working in different constant current operating states.
Above-mentioned constant-current circuit only adopts less basic components and parts can realize the constant current that precision is lower and controls, and circuit is simple, cost is lower, is applicable to the less demanding occasion of constant current accuracy.
Based on above-mentioned constant-current circuit 10, can build a kind of charging circuit.This charging circuit comprises above-mentioned constant-current circuit 10, and particularly, when charge power supply is 5V, operational amplifier U1 model is LM358, voltage-stabiliser tube ZD1 model is LM336, and the first resistance R 1 resistance is 510 Ω, and the second resistance R 2 resistances are 1K Ω, the 3rd resistance R 3 resistances are 3.3 Ω, and detecting resistance R sense resistance is 0.47 Ω.
The charging circuit of above-mentioned parameter can provide for the lithium ion battery of 3.7V 1200mAh the charging current of 300mAh.
Above-mentioned constant-current circuit 10 can also drive for LED constant current, using LED as Constant Current Load, forms a kind of LED drive circuit.
The above embodiment has only expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.
Claims (10)
1. a constant-current circuit, is characterized in that, comprises operational amplifier, regulates feedback unit and voltage regulation unit;
The in-phase input end of described operational amplifier is connected to working power by described voltage regulation unit, and by the first grounding through resistance; The output of described operational amplifier connects the adjustable side of described adjusting feedback unit by the second resistance;
The input of described adjusting feedback unit connects load by the 3rd resistance; The output of described adjusting feedback unit is by detecting grounding through resistance; The input of described adjusting feedback unit is also connected with the inverting input of described operational amplifier;
Described adjusting feedback unit flows through the size of current of described load according to the voltage-regulation of operational amplifier output, and input terminal voltage is fed back to the inverting input of operational amplifier.
2. constant-current circuit according to claim 1, is characterized in that, described voltage regulation unit is voltage-stabiliser tube, and the positive pole of described voltage-stabiliser tube is connected with described in-phase input end, and negative pole is connected with described working power.
3. constant-current circuit according to claim 1, it is characterized in that, described adjusting feedback unit is positive-negative-positive compound transistor, described positive-negative-positive compound transistor comprises the first positive-negative-positive triode and the second positive-negative-positive triode, and the base stage of described the first positive-negative-positive triode is connected with described the second resistance as the adjustable side of described adjusting feedback unit; Output as described adjusting feedback unit after the collector electrode of the collector electrode of described the first positive-negative-positive triode and the second positive-negative-positive triode is connected is connected with described detection resistance; The emitter of described the second positive-negative-positive triode is connected with described the 3rd resistance as the input of described adjusting feedback unit, and the emitter of described the first positive-negative-positive triode is connected with the base stage of described the second positive-negative-positive triode.
4. constant-current circuit according to claim 1, is characterized in that, at least one in described the first resistance, the second resistance and detection resistance is adjustable resistance.
5. a charging circuit, comprises constant-current circuit, and described constant-current circuit comprises operational amplifier, regulates feedback unit and voltage regulation unit;
The in-phase input end of described operational amplifier is connected to charge power supply by described voltage regulation unit, and by the first grounding through resistance; The output of described operational amplifier connects the adjustable side of described adjusting feedback unit by the second resistance;
The input of described adjusting feedback unit connects rechargeable battery by the 3rd resistance; The output of described adjusting feedback unit is by detecting grounding through resistance; The input of described adjusting feedback unit is also connected with the inverting input of described operational amplifier;
Described adjusting feedback unit flows through the electric current of described load according to the voltage-regulation of operational amplifier output, and input terminal voltage is fed back to the inverting input of operational amplifier.
6. charging circuit according to claim 5, is characterized in that, described voltage regulation unit is voltage-stabiliser tube, and the positive pole of described voltage-stabiliser tube is connected with described in-phase input end, and negative pole is connected with described working power.
7. charging circuit according to claim 6, it is characterized in that, described adjusting feedback unit is positive-negative-positive compound transistor, described positive-negative-positive compound transistor comprises the first positive-negative-positive triode and the second positive-negative-positive triode, and the base stage of described the first positive-negative-positive triode is connected with described the second resistance as the adjustable side of described adjusting feedback unit; Output as described adjusting feedback unit after the collector electrode of the collector electrode of described the first positive-negative-positive triode and the second positive-negative-positive triode is connected is connected with described detection resistance; The emitter of described the second positive-negative-positive triode is connected with described the 3rd resistance as the input of described adjusting feedback unit, and the emitter of described the first positive-negative-positive triode is connected with the base stage of described the second positive-negative-positive triode.
8. charging circuit according to claim 7, it is characterized in that, described charge power supply is 5V, described operational amplifier model is LM358, described voltage-stabiliser tube model is LM336, and described the first resistance is 510 Ω, and the second resistance is 1K Ω, the 3rd resistance is 3.3 Ω, and detecting resistance is 0.47 Ω.
9. charging circuit according to claim 5, is characterized in that, at least one in described the first resistance, the second resistance and detection resistance is adjustable resistance.
10. a LED drive circuit, comprises the constant-current circuit as described in claim 1 to 4 any one, for driving LED.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210367326.9A CN103702471A (en) | 2012-09-27 | 2012-09-27 | Constant-current circuit, charging circuit and LED driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210367326.9A CN103702471A (en) | 2012-09-27 | 2012-09-27 | Constant-current circuit, charging circuit and LED driving circuit |
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| CN201210367326.9A Pending CN103702471A (en) | 2012-09-27 | 2012-09-27 | Constant-current circuit, charging circuit and LED driving circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104968097A (en) * | 2014-11-22 | 2015-10-07 | 成都威邦科技有限公司 | Non-linear drain electrode driving system for blue LED lamp based on boost voltage stabilizing circuit |
| CN107277962A (en) * | 2016-04-06 | 2017-10-20 | 普诚科技股份有限公司 | Current control circuit |
| CN107979124A (en) * | 2017-08-08 | 2018-05-01 | 上海裕芯电子科技有限公司 | A kind of supply self adaptation charging circuit |
| CN108777038A (en) * | 2018-08-31 | 2018-11-09 | 广东绿网新能源科技有限公司 | Lock to intelligent car position and its use verification method |
| CN114325008A (en) * | 2020-10-12 | 2022-04-12 | 福州市瓦涵新能源科技有限公司 | Passive adjustable constant current electronic load |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104968097A (en) * | 2014-11-22 | 2015-10-07 | 成都威邦科技有限公司 | Non-linear drain electrode driving system for blue LED lamp based on boost voltage stabilizing circuit |
| CN107277962A (en) * | 2016-04-06 | 2017-10-20 | 普诚科技股份有限公司 | Current control circuit |
| CN107277962B (en) * | 2016-04-06 | 2019-04-02 | 普诚科技股份有限公司 | Current control circuit |
| CN107979124A (en) * | 2017-08-08 | 2018-05-01 | 上海裕芯电子科技有限公司 | A kind of supply self adaptation charging circuit |
| CN107979124B (en) * | 2017-08-08 | 2024-03-22 | 上海裕芯电子科技有限公司 | Power supply self-adaptive charging circuit |
| CN108777038A (en) * | 2018-08-31 | 2018-11-09 | 广东绿网新能源科技有限公司 | Lock to intelligent car position and its use verification method |
| CN108777038B (en) * | 2018-08-31 | 2024-04-09 | 广东绿网新能源科技有限公司 | Intelligent parking space ground lock and use verification method thereof |
| CN114325008A (en) * | 2020-10-12 | 2022-04-12 | 福州市瓦涵新能源科技有限公司 | Passive adjustable constant current electronic load |
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Application publication date: 20140402 |