CN205450863U - Positive adjustable constant current circuit of negative temperature coefficient - Google Patents
Positive adjustable constant current circuit of negative temperature coefficient Download PDFInfo
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- CN205450863U CN205450863U CN201521066528.5U CN201521066528U CN205450863U CN 205450863 U CN205450863 U CN 205450863U CN 201521066528 U CN201521066528 U CN 201521066528U CN 205450863 U CN205450863 U CN 205450863U
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Abstract
The utility model relates to a positive adjustable constant current circuit of negative temperature coefficient, first triode Q1's base and second triode Q2's collecting electrode are connected, and first triode Q1's projecting pole and second triode Q2's base are connected, first triode Q1's collecting electrode and load are connected, first resistance R1 connects microcontroller and first triode Q1's the base and the tie point of second triode Q2's collecting electrode, second resistance R2's one end and second triode Q2's projecting pole are connected, third resistance R3's one end and first triode Q1's projecting pole are connected with the tie point of second triode Q2's base. The utility model discloses output is positive negative temperature coefficient adjustable constant current source. When microcontroller output was the low level, constant current circuit was in the closed condition, when the microcontroller output high level, according to first resistance R1 and second resistance R2's ratio, load current can produce along with the change of temperature and just compensate, the burden compensates or it is invariable to keep.
Description
Technical field
This utility model relates to a kind of Positive and Negative Coefficient Temperature adjustable constant-flow circuit, particularly relates to a kind of can compensate for temperature and supply voltage impact and conveniently regulate the electronic circuit of output electric current.
Background technology
This utility model, mainly for automobile ECU Source Music, car body control module, needs the circuit of constant-current driving in climate control head and combination instrument etc., such as LED illumination circuit and some sensors etc..And cell voltage and electronic module operating temperature all can have bigger change on automobile.LED drive circuit and some sensor drive driving circuits need to drive electric current not change when change in voltage, and drive electric current to compensate the characteristic of circuit itself in a certain degree of increase or reduction along with the change of temperature, it is therefore necessary to update circuit design to meet the requirement improved constantly.
The most conventional constant-current drive circuit has following several:
1) special constant-current drives IC, and this circuit is generally of higher precision, but has the high cost of comparison, and it drives the temperature coefficient of electric current to be fixing less value, it is impossible to regulation and compensate powered circuit.
2) constant-current source made with constant voltage driving mirror current source or proportion current source, the precision of this circuit is not the highest, and its temperature coefficient is the most just, limits its application in some circuit.
Utility model content
For defect of the prior art, the purpose of this utility model is to provide a kind of constant current, it is easy to change sets electric current, the simultaneously positive and negative adjustable Positive and Negative Coefficient Temperature adjustable constant-flow circuit of its temperature coefficient.
For solving above-mentioned technical problem, this utility model Positive and Negative Coefficient Temperature adjustable constant-flow circuit, including the first audion Q1, the second audion Q2, the first resistance R1, the second resistance R2 and the 3rd resistance R3；The base stage of wherein said first audion Q1 is connected with the colelctor electrode of described second audion Q2, and the emitter stage of described first audion Q1 is connected with the base stage of described second audion Q2；The colelctor electrode of described first audion Q1 is connected with load；Described first resistance R1 connects the junction point of the base stage of microcontroller and described first audion Q1 and the colelctor electrode of described second audion Q2；One end of described second resistance R2 is connected with the emitter stage of described second audion Q2, the other end ground connection of described second resistance R2；One end of described 3rd resistance R3 and the emitter stage of described first audion Q1 are connected with the junction point of the base stage of described second audion Q2, the other end ground connection of described 3rd resistance R3.
Described first audion Q1 and described second audion Q2 is bipolarity NPN audion.
The I/O that input the is microcontroller output of this utility model Positive and Negative Coefficient Temperature adjustable constant-flow circuit, is output as the adjustable constant current of Positive and Negative Coefficient Temperature.When microcontroller is output as low level, constant-current circuit is closed；When microcontroller output high level, according to the first resistance R1 and the ratio of the second resistance R2, load current can produce along with the change of temperature and just compensate, negative compensate or keep constant.
Accompanying drawing explanation
Fig. 1 is this utility model Positive and Negative Coefficient Temperature adjustable constant-flow circuit diagram.
Detailed description of the invention
Below in conjunction with the accompanying drawings this utility model Positive and Negative Coefficient Temperature adjustable constant-flow circuit is described in further detail.
As it is shown in figure 1, this utility model Positive and Negative Coefficient Temperature adjustable constant-flow circuit, bipolarity NPN the first audion Q1, the second audion Q2, the first resistance R1, the second resistance R2 and the 3rd resistance R3.First audion Q1 provides for load and drives electric current, second audion Q2 and the 3rd resistance R3 constitutes negative-feedback circuit, when load current is higher than setting value, voltage on 3rd resistance R3 becomes big, it drives the second audion Q2, then the colelctor electrode of the second audion Q2 can absorb more electric current from node v2 and be lowered into the electric current of the first audion Q1 base stage, thus reduces the load current that the first audion Q1 colelctor electrode drives, and vice versa.
As microcontroller one constant voltage v1 of output, v3 node than v2 node the base stage of a low double pole triode to emitter stage economize on electricity press Vbe1, v4 node than v3 node the base stage of a low double pole triode to emitter stage economize on electricity press Vbe2, then v2-v4=Vbe1+Vbe2.If the first audion Q1 and the second audion Q2 is the ambipolar NPN audion of same model, it is believed that Vbe1=Vbe2, if and the first audion Q1 and the second audion Q2 has bigger current amplification factor, it is also possible to think that the base current of the first audion Q1 and the second audion Q2 may diminish to ignore.Electric current on so first resistance R1 is equal to the electric current on the second resistance R2, voltage v4=(v1-Vbe-Vbe) the * the second resistance R2/ (first resistance R1+ the second resistance R2) of the so second resistance R2, voltage v3=v4+Vbe=(v1-Vbe-Vbe) the * the second resistance R2/ (first resistance R1+ the second resistance R2)+Vbe=[v1* the second resistance R2+ (first resistance R1-the second resistance R2) * Vbe]/(first resistance R1+ the second resistance R2) on so the 3rd resistance R3, so load current is equal to the electric current on the 3rd resistance R3, then Iload=IR3=v3/ the 3rd resistance R3=[v1* the second resistance R2+ (first resistance R1-the second resistance R2) * Vbe]/[(first resistance R1+ the second resistance R2) the * the three resistance R3].As first resistance R1=the second resistance R2, the denominator of current formula does not has the component of Vbe, then current temperature coefficient is 0, and load current will not change with temperature；As the first resistance R1 > the second resistance R2, have positive Vbe, and the base stage of double pole triode and economizing on electricity of emitter stage press the negative temperature coefficient for-2mV/C in current formula denominator, then load current can rise along with temperature and reduce；As the first resistance R1, < during the second resistance R2, have negative Vbe in current formula denominator, then load current can become big along with temperature.
1. the value adjusting the 3rd resistance R3 can adjust load current easily；
2., when the electric current of load does not vary with temperature, make first resistance R1=the second resistance R2；
3., when load current needs negative temperature coefficient to do temperature-compensating, make the first resistance R1 > second resistance R2；
4., when load current needs positive temperature coefficient to do temperature-compensating, make the first resistance R1 < second resistance R2；
5. in the middle of the application of back lighting, microcontroller can export the pwm signal of different duty so that it is has the function that need not change circuit and dimmed by software.
Below the preferred embodiment created this utility model is illustrated, but this utility model is not limited to embodiment, those of ordinary skill in the art also can make modification or the replacement of all equivalents on the premise of this utility model creative spirit, and modification or the replacement of these equivalents are all contained in scope of the present application.
Claims (2)
1. a Positive and Negative Coefficient Temperature adjustable constant-flow circuit, it is characterised in that include the first audion Q1, the second audion Q2, the first resistance R1, the second resistance R2 and the 3rd resistance R3；The base stage of wherein said first audion Q1 is connected with the colelctor electrode of described second audion Q2, and the emitter stage of described first audion Q1 is connected with the base stage of described second audion Q2；The colelctor electrode of described first audion Q1 is connected with load；Described first resistance R1 connects the junction point of the base stage of microcontroller and described first audion Q1 and the colelctor electrode of described second audion Q2；One end of described second resistance R2 is connected with the emitter stage of described second audion Q2, the other end ground connection of described second resistance R2；One end of described 3rd resistance R3 and the emitter stage of described first audion Q1 are connected with the junction point of the base stage of described second audion Q2, the other end ground connection of described 3rd resistance R3.
Positive and Negative Coefficient Temperature adjustable constant-flow circuit the most according to claim 1, it is characterised in that described first audion Q1 and described second audion Q2 is bipolarity NPN audion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521066528.5U CN205450863U (en) | 2015-12-21 | 2015-12-21 | Positive adjustable constant current circuit of negative temperature coefficient |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521066528.5U CN205450863U (en) | 2015-12-21 | 2015-12-21 | Positive adjustable constant current circuit of negative temperature coefficient |
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|---|---|
| CN205450863U true CN205450863U (en) | 2016-08-10 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201521066528.5U Active CN205450863U (en) | 2015-12-21 | 2015-12-21 | Positive adjustable constant current circuit of negative temperature coefficient |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947762A (en) * | 2017-11-08 | 2018-04-20 | 陕西航空电气有限责任公司 | A kind of direct current transistor-type ignition device temperature-compensation circuit |
| CN111601429A (en) * | 2020-06-03 | 2020-08-28 | 西安中颖电子有限公司 | Constant current driving circuit |
| CN111665897A (en) * | 2020-06-19 | 2020-09-15 | 浙江驰拓科技有限公司 | Voltage stabilizing power supply circuit with negative temperature coefficient |
-
2015
- 2015-12-21 CN CN201521066528.5U patent/CN205450863U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947762A (en) * | 2017-11-08 | 2018-04-20 | 陕西航空电气有限责任公司 | A kind of direct current transistor-type ignition device temperature-compensation circuit |
| CN111601429A (en) * | 2020-06-03 | 2020-08-28 | 西安中颖电子有限公司 | Constant current driving circuit |
| CN111665897A (en) * | 2020-06-19 | 2020-09-15 | 浙江驰拓科技有限公司 | Voltage stabilizing power supply circuit with negative temperature coefficient |
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