CN203102060U - Current-limiting circuit - Google Patents
Current-limiting circuit Download PDFInfo
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- CN203102060U CN203102060U CN 201220739633 CN201220739633U CN203102060U CN 203102060 U CN203102060 U CN 203102060U CN 201220739633 CN201220739633 CN 201220739633 CN 201220739633 U CN201220739633 U CN 201220739633U CN 203102060 U CN203102060 U CN 203102060U
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- current
- triode
- audion
- limiting
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Abstract
The utility model relates to a current-limiting circuit which comprises sampling resistors, a filter capacitor connected with an output end, a current-limiting audion, a control audion, a control switch audion, a base of the current-limiting audion is connected with a collector of the control audion, an emitting electrode of the current-limiting audion is connected with an output end of a power source circuit, and the collector of the current-limiting audion is connected with the output end. A base of the control audion is connected with the output end of the power source circuit, an emitting electrode of the control audion is connected with a +12V power source, and the sampling resistors are connected between the output end of the power source circuit and the +12V power source. An emitting electrode of the control switch audion is grounded, a base of the control switch audion is connected with an enable signal end, a current-limiting resistor is connected between the base and the enable signal end in series, a collector of the control switch audion is connected with the base of the current-limiting audion, a divider resistor is connected between the collector the control switch audion and the base of the current-limiting audion in series, the collector of the control switch audion is connected with the +12V power source, and a divider resistor is connected between the collector of the control switch audion and the +12V power source. Current-limiting values do not fluctuate along with variation of voltage, is high in accuracy and has a negative temperature coefficient character, along with rising of circuit temperature, the current-limiting values are reduced, and electric energy is saved.
Description
Technical field
The utility model relates to a kind of current-limiting circuit, specifically a kind of current-limiting circuit that is used for the low-voltage powerline carrier communication module.
Background technology
Present known existing current-limiting circuit, the circuit structure complexity, circuit component is numerous, and production cost is higher, and has positive temperature coefficient (PTC), and the cut-off current precision is low.
Current-limiting circuit in the carrier module as shown in Figure 1, current-limiting circuit effect be the restriction carrier module right+maximum current consumption of 12V, if the current amplification factor H of triode
FE=300, the restriction output current should be no more than 156mA, and after circuit entered current-limit mode, triode V3 can generate heat, and temperature raises, and causes the current amplification factor H of triode
FEIncrease, thereby make output current become big, the temperature of triode V3 continues to raise, and continues to make output current to become big, has formed positive feedback, does not reach good current limitation effect.Current-limiting circuit also is subjected to the influence of supply voltage, and when supply voltage raise, cut-off current increased, and when supply voltage reduced, cut-off current reduced, the cut-off current instability.And the current amplification factor H of triode
FEDegree of accuracy lower, precision that also can first cut-off current.
The utility model content
The utility model is at existing current-limiting circuit complex structure, and problem such as circuit component is numerous, and production cost is higher, and has positive temperature coefficient (PTC), and the cut-off current precision is low has designed a kind of current-limiting circuit.
A kind of current-limiting circuit of the present utility model comprises two current sampling resistors in parallel, the filter capacitor that links to each other with output terminal, current limliting triode, control triode, gauge tap triode, filter capacitor ground connection; The base stage of current limliting triode is connected with the collector of control 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 of control triode links to each other with power circuit output end; The emitter of control triode is connected with+12V power supply; Two in parallel current sampling resistors be connected power circuit output end and+the 12V power supply between; The grounded emitter of gauge tap triode; The base stage of gauge tap triode is connected with the enable signal end, is connected with current-limiting resistance therebetween; The collector of gauge tap triode links to each other with the base stage of current limliting triode, is in series with divider resistance therebetween; The collector of control triode is connected with+12V power supply, is connected with divider resistance therebetween.
Preferably, current limliting triode and control triode are the positive-negative-positive triode, and the gauge tap triode is a NPN type triode.
Preferably, the base stage and the power circuit output end of control triode also are connected with divider resistance therebetween.
Preferably, be connected with buffer resistance between power circuit output end and the output terminal.
The beneficial effects of the utility model are: the cut-off current of current-limiting circuit does not fluctuate with the variation of voltage, the cut-off current precision is higher, current-limiting circuit has the characteristic of negative temperature coefficient, rising along with circuit temperature, cut-off current reduces, can save electric energy, circuit can not damaged because of overheated, improve the reliability of circuit.
Description of drawings
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 utility model.
Accompanying drawing 3 is the structured flowchart of current-limiting circuit of the present utility model.
Embodiment
A kind of current-limiting circuit of the present utility model, shown in Fig. 2 to 3, comprise two current sampling resistor R38, R39 in parallel, the filter capacitor C26 that links to each other with output terminal, current limliting triode Q7, control triode Q8, gauge tap triode Q9, current limliting triode Q7 and control triode Q8 are the positive-negative-positive triode, and gauge tap triode Q9 is a NPN type triode.
Filter capacitor C26 ground connection; The base stage of current limliting triode Q7 is connected with the collector of control 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 of control triode Q8 links to each other with power circuit output end VCC, also is connected with divider resistance R37 therebetween; The emitter of control triode Q8 is connected with+12V power supply; Two in parallel current sampling resistor R38, R39 be connected power circuit output end VCC and+the 12V power supply between; The grounded emitter of gauge tap triode Q9; The base stage of gauge tap triode Q9 is connected with the enable signal end, is connected with current-limiting resistance R42 therebetween; The collector of gauge tap triode Q9 links to each other with the base stage of current limliting triode Q7, is in series with divider resistance R40 therebetween; The collector of control triode Q8 is connected with+12V power supply, is connected with divider resistance R41 therebetween; Be connected with buffer resistance R36 between power circuit output end VCC and the output terminal.
When the voltage at current sampling resistor R38 and R39 two ends is higher than 0.6V, control triode Q8 conducting, the collector C of control triode Q8 and the voltage between the emitter E can be reduced to about 0.3V, divider resistance R37 is the less resistance of resistance, when the collector C of control triode Q8 and the voltage between the emitter E can be reduced to 0.3V, the also approximate 0.3V that reduces to of the collector B of current limliting triode Q7 and the voltage between the emitter E, this moment, current limliting triode Q7 turn-offed, and the emitter current of current limliting triode Q7 stops.
When current-limiting resistance R42 did not work, gauge tap triode Q9 blocked the electric current of divider resistance R40 and R41, reduced quiescent dissipation, had reached purpose of energy saving.
Divider resistance R40 and R41 provide base voltage for current limliting triode Q7, when+when the 12V power source voltage descends, the base stage of current limliting triode Q7 and the voltage U between the emitter
BeAlso can reduce, when the base stage of current limliting triode Q7 and the voltage U between the emitter
BeWhen being lower than 0.6V, current limliting triode Q7 turn-offs, and the emitter current of current limliting triode Q7 stops, and has reached the purpose 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 raises its temperature, after the temperature of current limliting triode Q7 and control triode Q8 raises, its separately base stage and the voltage U between the 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, the 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 be set to+during 12V, current limliting triode Q7 when different temperatures, the cut-off current of test current-limiting circuit, the result is as follows:
| Sequence number | Triode temperature ℃ | 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 (4)
1. current-limiting circuit, it is characterized in that, comprise two current sampling resistors (R38, R39) in parallel, the filter capacitor (C26) that links to each other with output terminal, current limliting triode (Q7), 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 of control 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 of control triode (Q8) links to each other with power circuit output end (VCC); The emitter of control triode (Q8) is connected with+12V power supply; Two current sampling resistors (R38, R39) in parallel be connected power circuit output end (VCC) and+the 12V power supply between; The grounded emitter of gauge tap triode (Q9); The base stage of gauge tap triode (Q9) is connected with the enable signal end, is connected with current-limiting resistance (R42) therebetween; The collector of gauge tap triode (Q9) links to each other with the base stage of current limliting triode (Q7), is in series with divider resistance (R40) therebetween; The collector of control triode (Q8) is connected with+12V power supply, is connected with divider resistance (R41) therebetween.
2. current-limiting circuit according to claim 1 is characterized in that, current limliting triode (Q7) and control triode (Q8) are the positive-negative-positive triode, and gauge tap triode (Q9) is a NPN type triode.
3. current-limiting circuit according to claim 1 and 2 is characterized in that, the base stage and the power circuit output end (VCC) of control triode (Q8) also are connected with divider resistance (R37) therebetween.
4. current-limiting circuit according to claim 1 and 2 is characterized in that, is connected with buffer resistance (R36) between power circuit output end (VCC) and the output terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220739633 CN203102060U (en) | 2012-12-30 | 2012-12-30 | Current-limiting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220739633 CN203102060U (en) | 2012-12-30 | 2012-12-30 | Current-limiting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203102060U true CN203102060U (en) | 2013-07-31 |
Family
ID=48853445
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220739633 Expired - Lifetime CN203102060U (en) | 2012-12-30 | 2012-12-30 | Current-limiting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203102060U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103049029A (en) * | 2012-12-30 | 2013-04-17 | 青岛东软载波科技股份有限公司 | Current-limiting circuit |
-
2012
- 2012-12-30 CN CN 201220739633 patent/CN203102060U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103049029A (en) * | 2012-12-30 | 2013-04-17 | 青岛东软载波科技股份有限公司 | Current-limiting circuit |
| CN103049029B (en) * | 2012-12-30 | 2015-03-18 | 青岛东软载波科技股份有限公司 | Current-limiting circuit |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20130731 |