CN103049029B - Current-limiting circuit - Google Patents
Current-limiting circuit Download PDFInfo
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- CN103049029B CN103049029B CN201210584586.1A CN201210584586A CN103049029B CN 103049029 B CN103049029 B CN 103049029B CN 201210584586 A CN201210584586 A CN 201210584586A CN 103049029 B CN103049029 B CN 103049029B
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Abstract
The invention relates to a current-limiting circuit. The current-limiting circuit comprises sampling resistors, a filtering capacitor, a current-limiting triode, a control triode and a control switch triode, wherein the filtering capacitor is connected with an output end. A base electrode of the current-limiting triode is connected with a collector electrode of the control triode, an emitting electrode of the current-limiting triode is connected with a power circuit output end, and a collector electrode of the current-limiting triode is connected with the output end. A base electrode of the control triode is connected with the power circuit output end, and an emitting electrode of the control triode is connected with a +12V power supply. The sampling resistors are connected between the power circuit output end and the +12V power supply, an emitting electrode of the control switch triode is grounded, a base electrode of the control switch triode is connected with an enable signal end, a current-limiting resistor is serially connected between the base electrode of the control switch triode and the enable signal end, a collector electrode of the control switch triode is connected with the base electrode of the current-limiting triode, a voltage-dividing resistor is serially connected between the collector electrode of the control switch triode and the base electrode of the current-limiting triode, the collector electrode of the control triode is connected with the +12V power supply, and a voltage-dividing resistor is serially connected between the collector electrode of the control triode and the +12V power supply. A current-limiting value of the current-limiting circuit does not fluctuate along with change of voltage and is high in precision. Besides, the current-limiting circuit has the negative temperature coefficient characteristic, the current-limiting value is decreased along with temperature increase of the circuit, and accordingly electric energy is saved.
Description
Technical field
The present invention relates to a kind of current-limiting circuit, specifically a kind of for the current-limiting circuit in low-voltage power line carrier communication module.
Background technology
Existing current-limiting circuit known at present, circuit structure is complicated, and circuit component is numerous, and production cost is higher, and there is positive temperature coefficient (PTC), and cut-off current precision is low.
Current-limiting circuit in carrier module as shown in Figure 1, current-limiting circuit effect is the maximum current consumption of the right+12V of restriction carrier module, if the current amplification factor H of triode
fE=300, restriction output current should be no more than 156mA, and after circuit enters current-limit mode, triode V3 can generate heat, and temperature raises, and causes the current amplification factor H of triode
fEincrease, thus make output current become large, the temperature of triode V3 continues to raise, and continues to make output current become large, defines positive feedback, do not reach good current limitation effect.Current-limiting circuit is also subject to the impact of supply voltage, and when supply voltage raises, cut-off current increases, and when the supply voltage decreases, cut-off current reduces, and cut-off current is unstable.And the current amplification factor H of triode
fEdegree of accuracy lower, also can the precision of first cut-off current.
Summary of the invention
The present invention is directed to existing current-limiting circuit complex structure, the problems such as circuit component is numerous, and production cost is higher, and there is positive temperature coefficient (PTC), and cut-off current precision is low, devise a kind of current-limiting circuit.
A kind of current-limiting circuit of the present invention, comprises two current sampling resistors, the filter capacitor be connected with output terminal, current limliting triode in parallel, controls triode, gauge tap triode, filter capacitor ground connection; The base stage of current limliting triode is connected with the collector controlling triode; The collector of current limliting triode is connected with output terminal; The emitter of current limliting triode is connected with power circuit output end; The base stage controlling triode is connected with power circuit output end; The emitter controlling triode is connected with+12V power supply; Two current sampling resistors in parallel are connected between power circuit output end and+12V power supply; The grounded emitter of gauge tap triode; The base stage of gauge tap triode is connected with enable signal end, is connected with current-limiting resistance therebetween; The collector of gauge tap triode is connected with the base stage of current limliting triode, is in series with the first divider resistance therebetween; The collector controlling triode is connected with+12V power supply, is connected with the second divider resistance therebetween.
Preferably, current limliting triode and control triode are PNP type triode, and gauge tap triode is NPN type triode.
Preferably, the base stage and the power circuit output end that control triode are also connected with the 3rd divider resistance therebetween.
Preferably, buffer resistance is connected with between power circuit output end and output terminal.
The invention has the beneficial effects as follows: the cut-off current of current-limiting circuit does not fluctuate with the change of voltage, cut-off current precision is higher, current-limiting circuit has the characteristic of negative temperature coefficient, along with the rising of circuit temperature, cut-off current reduces, can electric energy be saved, make circuit can not damage because of overheated simultaneously, improve the reliability of circuit.
Accompanying drawing explanation
Accompanying drawing 1 is the circuit theory diagrams of existing current-limiting circuit;
Accompanying drawing 2 is the circuit theory diagrams of current-limiting circuit of the present invention;
Accompanying drawing 3 is the structured flowchart of current-limiting circuit of the present invention.
Embodiment
A kind of current-limiting circuit of the present invention, as shown in Fig. 2 to 3, comprise two current sampling resistor R38, R39, the filter capacitor C26 be connected with output terminal, current limliting triode Q7 in parallel, control triode Q8, gauge tap triode Q9, current limliting triode Q7 and control triode Q8 is PNP type triode, and gauge tap triode Q9 is NPN type triode.
Filter capacitor C26 ground connection; The base stage of current limliting triode Q7 is connected with the collector controlling triode Q8; The collector of current limliting triode Q7 is connected with output terminal; The emitter of current limliting triode Q7 is connected with power circuit output end VCC; The base stage controlling triode Q8 is connected with power circuit output end VCC, is also connected with the 3rd divider resistance R37 therebetween; The emitter controlling triode Q8 is connected with+12V power supply; Two current sampling resistors R38, R39 in parallel are connected between power circuit output end VCC and+12V power supply; The grounded emitter of gauge tap triode Q9; The base stage of gauge tap triode Q9 is connected with enable signal end, is connected with current-limiting resistance R42 therebetween; The collector of gauge tap triode Q9 is connected with the base stage of current limliting triode Q7, is in series with the first divider resistance R40 therebetween; The collector controlling triode Q8 is connected with+12V power supply, is connected with the second divider resistance R41 therebetween; Buffer resistance R36 is connected with between power circuit output end VCC and output terminal.
When the voltage at current sampling resistor R38 and R39 two ends is higher than 0.6V, control triode Q8 conducting, the voltage controlled between the collector C of triode Q8 and emitter E can be reduced to about 0.3V, 3rd divider resistance R37 is the resistance that resistance is less, when voltage between the collector C controlling triode Q8 and emitter E can be reduced to 0.3V, voltage between the collector B of current limliting triode Q7 and emitter E is also approximate reduces to 0.3V, now current limliting triode Q7 turns off, and the emitter current of current limliting triode Q7 stops.
When current-limiting resistance R42 does not work, gauge tap triode Q9 blocks the electric current of the first divider resistance R40 and the second divider resistance R41, reduces quiescent dissipation, reaches energy-conservation object.
First divider resistance R40 and the second divider resistance R41 provides base voltage for current limliting triode Q7, when the voltage drop of+12V power supply, and the voltage U between the base stage of current limliting triode Q7 and emitter
bealso can reduce, the voltage U between the base stage and emitter of current limliting triode Q7
beduring lower than 0.6V, current limliting triode Q7 turns off, and the emitter current of current limliting triode Q7 stops, and reaches the object of under-voltage protection.
When current-limiting circuit enters current-limit mode, the temperature of current limliting triode Q7 rises, control triode Q8 also can receive the heat that current limliting triode Q7 passes over its temperature is raised, current limliting triode Q7 and control triode Q8 temperature rising after, the voltage U between its respective base stage and emitter
bereduce, cut-off current reduces, and makes current-limiting circuit have the characteristic of negative temperature coefficient.
Under different power circuit output end VCC voltage, the cut-off current of test current-limiting circuit, result is as follows:
| Sequence number | Supply voltage V | Cut-off current mA |
| 1 | 6 | 61 |
| 2 | 7 | 86 |
| 3 | 8 | 103 |
| 4 | 9 | 112 |
| 5 | 10 | 115 |
| 6 | 11 | 118 |
| 7 | 12 | 120 |
| 8 | 13 | 121 |
| 9 | 14 | 122 |
| 10 | 15 | 123 |
| 11 | 16 | 124 |
| 12 | 17 | 125 |
| 13 | 18 | 125 |
| 14 | 19 | 125 |
| 15 | 20 | 125 |
| 16 | 22 | 125 |
| 17 | 24 | 125 |
| 18 | 26 | 125 |
| 19 | 28 | 125 |
| 20 | 30 | 125 |
When power circuit output end VCC voltage is set to+12V, current limliting triode Q7 is when different temperatures, and test the cut-off current of current-limiting circuit, result is as follows:
| Sequence number | Triode temperature DEG C | Cut-off current mA |
| 1 | 20 | 123 |
| 2 | 30 | 120 |
| 3 | 40 | 116 |
| 4 | 50 | 112 |
| 5 | 60 | 108 |
| 6 | 70 | 104 |
| 7 | 80 | 101 |
| 8 | 90 | 97 |
| 9 | 100 | 93 |
| 10 | 110 | 90 |
| 11 | 120 | 86 |
| 12 | 130 | 82 |
| 13 | 140 | 78 |
| 14 | 150 | 75 |
Claims (1)
1. a current-limiting circuit, it is characterized in that, comprise two current sampling resistors (R38, R39), the filter capacitor (C26) be connected with output terminal, current limliting triode (Q7) in parallel, control triode (Q8), gauge tap triode (Q9), filter capacitor (C26) ground connection; The base stage of current limliting triode (Q7) is connected with the collector controlling triode (Q8); The collector of current limliting triode (Q7) is connected with output terminal; The emitter of current limliting triode (Q7) is connected with power circuit output end (VCC); The base stage controlling triode (Q8) is connected with power circuit output end (VCC); The emitter controlling triode (Q8) is connected with+12V power supply; Two current sampling resistors (R38, R39) in parallel are connected between power circuit output end (VCC) and+12V power supply; The grounded emitter of gauge tap triode (Q9); The base stage of gauge tap triode (Q9) is connected with enable signal end, is connected with current-limiting resistance (R42) therebetween; The collector of gauge tap triode (Q9) is connected with the base stage of current limliting triode (Q7), is in series with the first divider resistance (R40) therebetween; The collector controlling triode (Q8) is connected with+12V power supply, be connected with the second divider resistance (R41) therebetween, current limliting triode (Q7) and control triode (Q8) are PNP type triode, gauge tap triode (Q9) is NPN type triode, the base stage and the power circuit output end (VCC) that control triode (Q8) are also connected with the 3rd divider resistance (R37) therebetween, are connected with buffer resistance (R36) between power circuit output end (VCC) and output terminal.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210584586.1A CN103049029B (en) | 2012-12-30 | 2012-12-30 | Current-limiting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210584586.1A CN103049029B (en) | 2012-12-30 | 2012-12-30 | Current-limiting circuit |
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| CN103049029A CN103049029A (en) | 2013-04-17 |
| CN103049029B true CN103049029B (en) | 2015-03-18 |
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| CN201210584586.1A Active CN103049029B (en) | 2012-12-30 | 2012-12-30 | Current-limiting circuit |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103729006A (en) * | 2013-11-21 | 2014-04-16 | 成都市宏山科技有限公司 | Camera protection circuit |
| CN105140997A (en) * | 2015-09-09 | 2015-12-09 | 成都川睿科技有限公司 | Intelligent lamp charger of intelligent traffic system |
| CN107888063B (en) * | 2018-02-11 | 2019-10-01 | 漳州科华技术有限责任公司 | A kind of output current peak coefficient method and device improving inverter |
| CN112267549A (en) * | 2020-10-10 | 2021-01-26 | 浙江飞创环境科技有限公司 | Integrated pump station |
| CN112485494A (en) * | 2020-11-17 | 2021-03-12 | 天津津航计算技术研究所 | Current detection circuit based on triode |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101505055A (en) * | 2008-12-30 | 2009-08-12 | 上海英联电子系统有限公司 | Active surge current control circuit |
| CN101771272A (en) * | 2010-03-02 | 2010-07-07 | 南京亚派科技实业有限公司 | Over current protection circuit |
| CN102082430A (en) * | 2011-01-27 | 2011-06-01 | 广州金升阳科技有限公司 | Surge suppression circuit |
| CN203102060U (en) * | 2012-12-30 | 2013-07-31 | 青岛东软载波科技股份有限公司 | Current-limiting circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201383668Y (en) * | 2009-02-24 | 2010-01-13 | 中山大洋电机股份有限公司 | Over-current protection circuit and motor controller applied to same |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101505055A (en) * | 2008-12-30 | 2009-08-12 | 上海英联电子系统有限公司 | Active surge current control circuit |
| CN101771272A (en) * | 2010-03-02 | 2010-07-07 | 南京亚派科技实业有限公司 | Over current protection circuit |
| CN102082430A (en) * | 2011-01-27 | 2011-06-01 | 广州金升阳科技有限公司 | Surge suppression circuit |
| CN203102060U (en) * | 2012-12-30 | 2013-07-31 | 青岛东软载波科技股份有限公司 | Current-limiting circuit |
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| CN103049029A (en) | 2013-04-17 |
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