CN208352958U - Current foldback circuit - Google Patents
Current foldback circuit Download PDFInfo
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- CN208352958U CN208352958U CN201821214261.3U CN201821214261U CN208352958U CN 208352958 U CN208352958 U CN 208352958U CN 201821214261 U CN201821214261 U CN 201821214261U CN 208352958 U CN208352958 U CN 208352958U
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- switch unit
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- triode
- input terminal
- foldback circuit
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Abstract
The utility model provides a kind of current foldback circuit, is related to technical field of electricity.Current foldback circuit, for preventing circuit caused by load short circuits from damaging.Wherein sampling unit connects voltage output end and for exporting acquisition signal.A reference source built-in reference voltage, by reference to voltage on-off signal corresponding with the acquisition comparison result output of signal.First switch unit, is controlled by a reference source, is turned on or off according to on-off signal.Second switch unit is controlled by first switch unit, is connected with the conducting of first switch so that entire circuit output burning voltage, or with first switch disconnection and disconnect to protect circuit.The protection circuit structure of the utility model is simple, at low cost without high protection chip.Sampling unit and a reference source can determine higher current precision, be quick on the draw.After short circuit or overload are removed, current foldback circuit can voluntarily restore.
Description
Technical field
The utility model relates to technical field of electricity, in particular to a kind of current foldback circuit.
Background technique
The intelligent electric meter rapid deployment in worldwide at present, the external a variety of communication modules of intelligent electric meter, such as 4G,
PLC, RF etc..External interface needs short circuit and overcurrent protection, to prevent external overload or accidental short circuit, damages electric energy meter,
Cause security risk.
Existing interface power protects circuit, LDO (linear voltage stabilization similar in some operating limit electric currents and protective current
Device), this scheme relies on the Thermal protection after LDO overcurrent, so that LDO work causes power consumption excessive, pole in 1 boundary's point of Thermal protection
Device easy to damage, burns circuit.Some uses current-limiting protection chip, and market chip is divided into constant-current and (continues electricity
Stream) and latch-off (locking) two types, it is at high cost.Use comparator also, operational amplifier build circuit, cost
It is high.
Utility model content
The purpose of this utility model is to provide a kind of current foldback circuits, solve the interface power protection electricity of the prior art
Road is easily damaged in actual use, and circuit is protected to build required problem at high cost.
In order to solve the above technical problems, the utility model adopts the following technical solution:
A kind of current foldback circuit, applied to the interface for having loaded electrical equipment, the interface has voltage output
End, the load connect the output end of the current foldback circuit；It is characterized in that, the current foldback circuit includes: sampling
Unit, with input terminal, the first output end and second output terminal；The input terminal of the sampling unit connects the voltage output
End；A reference source, with input terminal and output end；Its input terminal connects the second output terminal of the sampling unit, the benchmark
Source generates on-off signal for being compared with the output signal of the second output terminal, and by comparing result；The benchmark
The output end in source is for exporting the on-off signal；First switch unit, with controlled end, input terminal and output end；It is described
The controlled end of first switch unit connects the output end of a reference source, adopts described in the input terminal connection of the first switch unit
First output end of sample unit；Second switch unit, with controlled end, input terminal and output end；The second switch unit
Controlled end connect the output end of the first switch unit, the input terminal of the second switch unit connects the sampling unit
The first output end, the output end of the second switch unit is the output end of the current foldback circuit, described for connecting
Load.
One embodiment according to the present utility model, the first switch unit include the first triode (Q1)；Described
The base stage of one triode (Q1) is the controlled end of the first switch unit, and the transmitting of first triode (Q1) is extremely described
The current collection of the input terminal of first switch unit, first triode (Q1) extremely states the output end of first switch unit.
One embodiment according to the present utility model, the first switch unit further include the first base resistance (R2) and the
Two base resistances (R5)；Base stage and the sampling unit of first base resistance (R2) set on first triode (Q1)
The first output end；Second base resistance (R5) is set to the defeated of base stage and a reference source of first triode (Q1)
Between outlet.
One embodiment according to the present utility model, the first switch unit further include third base resistance (R6) and limit
Leakage resistance (R7)；The third base resistance (R6) is set to the collector and the second switch list of first triode (Q1)
Between the controlled end of member；The collector of first triode (Q1) is grounded through the current-limiting resistance (R7).
One embodiment according to the present utility model, the second switch unit include the second triode (Q2) and the three or three
Pole pipe (Q3)；The base stage of second triode (Q2) is the controlled end of the second switch unit, second triode
(Q2) emitter ground connection, the collector of second triode (Q2) connect the base stage of the third transistor (Q3)；It is described
The input terminal of the extremely described second switch unit of transmitting of third transistor (Q3), the current collection of the third transistor (Q3) is extremely
The output end of the second switch unit.
One embodiment according to the present utility model, the second switch unit further include the first biasing resistor (R9) and the
Two biasing resistors (R4)；Base stage and the sampling unit of first biasing resistor (R9) set on the third transistor (Q3)
The first output end between；Second biasing resistor (R4) is set to the base stage and the described 2nd 3 of the third transistor (Q3)
Between the collector of pole pipe (Q2).
One embodiment according to the present utility model, the sampling unit include sampling resistor (R1), the first divider resistance
(R3) and the second divider resistance (R8)；One end of the sampling resistor (R1) is the input terminal of the sampling unit, described to adopt
The other end of sample resistance (R1) is the first output end of the sampling unit；First divider resistance (R3) with described second point
Piezoresistance (R8) series connection, the other end of first divider resistance (R3) connects the first output end of the sampling unit, described
The other end of second divider resistance (R8) is grounded；The connection of first divider resistance (R3) and second divider resistance (R8)
Point is the second output terminal of the sampling unit.
One embodiment according to the present utility model, the sampling unit further include protection capacitor (C1)；The protection electricity
It is in parallel with the second divider resistance (R8) to hold (C1).
One embodiment according to the present utility model, the extremely described input terminal of control of a reference source (U1), the base
The cathode of quasi- source (U1) is the output end, the plus earth of a reference source (U1).
As shown from the above technical solution, the utility model at least has the following advantages that and good effect:
Current foldback circuit provided by the utility model is loaded applied in the interface circuit of electrical equipment for preventing
Circuit caused by short circuit and overload damages, or for exporting constant current.Wherein, the voltage output of sampling unit connecting interface
It holds and is used to export acquisition signal.A reference source built-in reference voltage, reference voltage are set jointly and the cooperation with sampling unit
A fixed protection value, and according to protection value on-off signal corresponding with the acquisition comparison result output of signal.First switch unit
It is turned on or off according to the on-off signal.Second switch unit is controlled by first switch unit, with leading for first switch
Logical state and be connected so that entire circuit output burning voltage, or with first switch disconnection and disconnect to protect circuit.
The circuit structure of the utility model is simple, does not use high protection chip, at low cost.Its sampling unit can determine with a reference source
Fixed higher current precision is quick on the draw to realize better current protection.After short circuit or overload are removed, overcurrent protection electricity
Road can voluntarily restore.
Detailed description of the invention
Fig. 1 is the circuit diagram of current foldback circuit in the utility model embodiment.
The reference numerals are as follows: 100- current foldback circuit；1- sampling unit；2- first switch unit；3- second is opened
Close unit.
Specific embodiment
The exemplary embodiment for embodying the utility model features and advantages will describe in detail in the following description.It should be understood that
Be that the utility model can have various variations in different embodiments, all do not depart from the model of the utility model
It encloses, and the descriptions and illustrations are essentially for illustration purposes, rather than to limit the utility model.
Fig. 1 is please referred to, Fig. 1 shows a kind of specific structure of current foldback circuit 100 provided in this embodiment, is applied to
Electrical equipment is for example in the interface circuit of intelligent electric meter.The interface of intelligent electric meter is connected to load (RL), and interface has voltage output
VIN is held, current foldback circuit has output end VOUT, and load (RL) is connected to output end VOUT.Current foldback circuit 100 is by adopting
Sample unit 1, a reference source (U1), first switch unit 2 and second switch unit 3 form degeneration factor.Circuit structure letter
It is single, it is at low cost, output electric current can be adjusted, prevents circuit caused by short circuit from damaging.
The input terminal of sampling unit 1 connects voltage output end VIN, for acquiring current signal.The acquisition signal is also defeated
A feedback quantity of outlet VOUT, the current signal are proportional to VOUT.Its output end is for exporting acquisition signal.
Sampling unit includes sampling resistor (R1), protection capacitor (C1), the first divider resistance (R3) and the second partial pressure electricity
It hinders (R8)；One end of sampling resistor (R1) is the input terminal of sampling unit, and the other end of sampling resistor (R1) is sampling unit
First output end；First divider resistance (R3) is connected with the second divider resistance (R8), and the other end of the first divider resistance (R3) connects
Connect the first output end of sampling unit, the other end ground connection of the second divider resistance (R8)；First divider resistance (R3) with second point
The tie point of piezoresistance (R8) is the second output terminal of sampling unit.Protect capacitor (C1) in parallel with the second divider resistance (R8).
The effect of protection capacitor (C1) is, when output short-circuit, eliminates oscillation caused by negative-feedback, prevents the second divider resistance (R8)
Voltage jump.In addition, the effect of sampling resistor (R1) is: sample rate current, switching current signal is voltage signal, and exports and adopt
Sample voltage.
The control extremely input terminal of a reference source (U1), for receiving the acquisition signal of sampling unit 1.The yin of a reference source (U1)
Extremely output end, for exporting the on-off signal according to acquisition signal.The plus earth of a reference source (U1).In the present embodiment,
Preferably, the model TL431 of a reference source (U1).For TL431 as controllable accurate source of stable pressure, cost performance is very high, and usability is extensive.
In other embodiments, a reference source of a reference source (U1) or other models.
The inside of a reference source (U1) has a reference voltage Vref, which is usually 2.5v or 1.25v.
A reference source (U1) is compared by reference to voltage Vref with the acquisition signal of sampling unit 1, and is led according to comparison result realization
The state that on-off is opened, if if conducting, a reference source (U1) can export one by two divider resistances of sampling unit 1 and stablize electricity
Pressure is Vref* (1+R3/R8).Further, reference voltage Vref cooperation sampling unit 1 sampling resistor (R1) and two points
Piezoresistance common setups overcurrent value(the maximum load current that circuit can bear surpasses
Overcurrent value I or short circuit are crossed, circuital current can be stablized in the overcurrent value I).
First switch unit 2 is controlled by a reference source (U1).Specifically, first switch unit 2 is according to the logical of a reference source (U1)
Break signal and on and off therewith.First switch unit 2 be used as switching circuit, can faint digital signal, carry out into
The amplification of one step, then exports, it is therefore intended that improve the driving capability of output.
First switch unit 2 includes the first triode (Q1), the first base resistance (R2), the second base resistance (R5), the
Three base resistances (R6) and current-limiting resistance (R7).The base stage of first triode (Q1) be first switch unit 2 controlled end, first
The input terminal of the transmitting extremely first switch unit 2 of triode (Q1), the current collection of the first triode (Q1) extremely first switch list
The output end of member 2.First base resistance (R2) set on the first triode (Q1) base stage and sampling unit 1 the first output end it
Between.Second base resistance (R5) is between the base stage of the first triode (Q1) and the output end of a reference source (U1).Third base stage
Resistance (R6) is between the collector of the first triode (Q1) and the controlled end of second switch unit 3.First triode (Q1)
Collector through current-limiting resistance (R7) be grounded.
Second switch unit 3 is controlled by first switch unit 2, completely opens for forming one with first switch unit 2
Powered-down road.
Second switch unit 3 includes the second triode (Q2), third transistor (Q3), the first biasing resistor (R9) and second
Biasing resistor (R4).Wherein, controlled end of the base stage of the second triode (Q2) as second switch unit 3, for connecting first
The output end of switch unit 2.The emitter of second triode (Q2) is grounded.The collector connection the three or three of second triode (Q2)
The base stage of pole pipe (Q3).Input terminal of the emitter of third transistor (Q3) as second switch unit 3, it is single for connecting sampling
First output end of member 1.Output end of the collector of third transistor (Q3) as second switch unit 3, for connecting output
Hold VOUT.Further, the first biasing resistor (R9) is set on the base stage of third transistor (Q3) and the first output of sampling unit 1
Between end；Second biasing resistor (R4) is between the base stage of third transistor (Q3) and the collector of the second triode (Q2).
In order to understand those skilled in the art more, the work of current foldback circuit 100 provided by the utility model is former
The case where managing, being in different working condition using circuit below is illustrated.
One, the following are load normal circuit conditions:
When load (RL) normally, load current be less than overcurrent value I when, circuit work normally.Further, sampling unit
Sampling resistor (R1) in 1 flows through electric current less than overcurrent value I.The input voltage V1 of sampling unit 1 is greater than Vref* (1+R3/R8),
The voltage of second divider resistance (R8) is greater than a reference source (U1) reference voltage Vref, a reference source (U1) conducting, and electric current flows through first
Base resistance (R2), the second base resistance (R5).The voltage difference of first triode (Q1) emitter and its base stage is greater than its unlatching
Voltage, the first triode (Q1) conducting.Electric current flows through third base resistance (R6), the second triode (Q2) base stage and its emitter
Voltage difference be greater than cut-in voltage, the second triode (Q2) conducting.Electric current flows through the first biasing resistor (R9) and the second biased electrical
It hinders (R4), the voltage difference of third transistor (Q3) emitter and base stage is greater than cut-in voltage, third transistor (Q3) conducting, output
Voltage VOUT is approximately equal to input voltage VIN.
Two, the following are load overload or the circuit conditions of short circuit:
When output short-circuit or excessive load (RL) electric current, sampling resistor (R1) flows through electric current greater than overcurrent value I.V1 voltage
Less than Vref* (1+R3/R8), the voltage of the second divider resistance (R8) is less than a reference source (U1) reference voltage Vref, a reference source
(U1) end, no electric current flows through the first base resistance (R2), the second base resistance (R5).The base stage electricity of first triode (Q1)
Pressure is V1, equal with emitter voltage, the first triode (Q1) cut-off.There is no electric current to flow through third base resistance (R6), second
Triode (Q2) base voltage is 0V, equal with its emitter voltage, the second triode (Q2) cut-off.There is no electric current to flow through first
Biasing resistor (R9) and the second biasing resistor (R4), third transistor (Q3) base voltage is V1, equal with its emitter voltage,
Third transistor (Q3) cut-off, realizes the shutdown of entire circuit.After short circuit is removed with overload, the electricity of sampling resistor (R1) is flowed through
Rheology is small, and V1 becomes larger, and the second divider resistance (R8) voltage is greater than reference voltage, and a reference source (U1) is connected again, and circuit can repeat
Adjustment.Further, due to the effect of protection capacitor (C1), the second divider resistance (R8) voltage cannot be mutated, and output electric current becomes
In balance, until being equal to protective current.As load current is more than protective current and is increased, output voltage VO UT can gradually drop
It is low, to maintain outputting current steadily in protective current point.
In conclusion a kind of current foldback circuit 100 provided by the utility model has the following advantages that and good effect:
1. current foldback circuit 100 provided by the utility model is made of multiple common triodes, capacitor and resistance,
Circuit is simple and reliable, small power consumption and at low cost.
2. function is reliable, it is quick on the draw, has the characteristics that output can be restored automatically after short circuit or overload are removed.Protective current
It is more much smaller than short circuit current, circuit will not be damaged short circuit for a long time.
3. current precision is high, in the case where stabilized input voltage, current precision is by sampling unit 1 and a reference source (U1)
Precision determine, can achieve within 5% or higher.
Although describing the utility model with reference to several exemplary embodiments, it is to be understood that, term used is to say
Term bright and exemplary, and not restrictive.Since the utility model can be embodied in a variety of forms without departing from practical
Novel spirit or essence, it should therefore be appreciated that above embodiment is not limited to any of the foregoing details, and should be in accompanying right
Widely explained in spirit and scope defined by it is required that, thus fall into whole variations in claim or its equivalent scope and
Remodeling all should be appended claims and be covered.
Claims (9)
1. a kind of current foldback circuit, applied to the interface for having loaded electrical equipment, the interface has voltage output end,
The load connects the output end of the current foldback circuit；It is characterized in that, the current foldback circuit includes:
Sampling unit, with input terminal, the first output end and second output terminal；Described in the input terminal connection of the sampling unit
Voltage output end；
A reference source, with input terminal and output end；Its input terminal connects the second output terminal of the sampling unit, the benchmark
Source generates on-off signal for being compared with the output signal of the second output terminal, and by comparing result；The benchmark
The output end in source is for exporting the on-off signal；
First switch unit, with controlled end, input terminal and output end；Described in the controlled end connection of the first switch unit
The input terminal of the output end of a reference source, the first switch unit connects the first output end of the sampling unit；
Second switch unit, with controlled end, input terminal and output end；Described in the controlled end connection of the second switch unit
The input terminal of the output end of first switch unit, the second switch unit connects the first output end of the sampling unit, institute
The output end for stating second switch unit is the output end of the current foldback circuit, for connecting the load.
2. current foldback circuit according to claim 1, it is characterised in that:
The first switch unit includes the first triode (Q1)；
The base stage of first triode (Q1) is the controlled end of the first switch unit, the hair of first triode (Q1)
Emitter-base bandgap grading is the input terminal of the first switch unit, the extremely described first switch unit of the current collection of first triode (Q1)
Output end.
3. current foldback circuit according to claim 2, it is characterised in that:
The first switch unit further includes the first base resistance (R2) and the second base resistance (R5)；
First base resistance (R2) is set to the base stage of first triode (Q1) and the first output of the sampling unit
End；Second base resistance (R5) is set between the base stage of first triode (Q1) and the output end of a reference source.
4. current foldback circuit according to claim 3, it is characterised in that:
The first switch unit further includes third base resistance (R6) and current-limiting resistance (R7)；
The third base resistance (R6) is set to the collector of first triode (Q1) and the institute of the second switch unit
It states between controlled end；The collector of first triode (Q1) is grounded through the current-limiting resistance (R7).
5. current foldback circuit described in any one of -4 according to claim 1, it is characterised in that:
The second switch unit includes the second triode (Q2) and third transistor (Q3)；
The base stage of second triode (Q2) is the controlled end of the second switch unit, the hair of second triode (Q2)
Emitter grounding, the collector of second triode (Q2) connect the base stage of the third transistor (Q3)；Three or three pole
Manage the input terminal of the extremely described second switch unit of transmitting of (Q3), the current collection extremely described second of the third transistor (Q3)
The output end of switch unit.
6. current foldback circuit according to claim 5, it is characterised in that:
The second switch unit further includes the first biasing resistor (R9) and the second biasing resistor (R4)；
First biasing resistor (R9) is set on the base stage of the third transistor (Q3) and the first output of the sampling unit
Between end；Base stage and second triode (Q2) of second biasing resistor (R4) set on the third transistor (Q3)
Between collector.
7. current foldback circuit according to claim 1, it is characterised in that:
The sampling unit includes sampling resistor (R1), the first divider resistance (R3) and the second divider resistance (R8)；
One end of the sampling resistor (R1) is the input terminal of the sampling unit, and the other end of the sampling resistor (R1) is institute
State the first output end of sampling unit；
First divider resistance (R3) is connected with second divider resistance (R8), first divider resistance (R3) it is another
End connects the first output end of the sampling unit, the other end ground connection of second divider resistance (R8)；First partial pressure
Resistance (R3) and the tie point of second divider resistance (R8) are the second output terminal of the sampling unit.
8. current foldback circuit according to claim 7, it is characterised in that:
The sampling unit further includes protection capacitor (C1)；The protection capacitor (C1) and second divider resistance (R8) are simultaneously
Connection.
9. current foldback circuit according to claim 1, it is characterised in that:
The extremely described input terminal of control of a reference source (U1), the cathode of a reference source (U1) is the output end, described
The plus earth of a reference source (U1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821214261.3U CN208352958U (en) | 2018-07-27 | 2018-07-27 | Current foldback circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821214261.3U CN208352958U (en) | 2018-07-27 | 2018-07-27 | Current foldback circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN208352958U true CN208352958U (en) | 2019-01-08 |
Family
ID=64906112
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201821214261.3U Active CN208352958U (en) | 2018-07-27 | 2018-07-27 | Current foldback circuit |
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| Country | Link |
|---|---|
| CN (1) | CN208352958U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022100267A1 (en) * | 2020-11-12 | 2022-05-19 | 深圳Tcl数字技术有限公司 | Overcurrent protection trigger circuit and device |
-
2018
- 2018-07-27 CN CN201821214261.3U patent/CN208352958U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022100267A1 (en) * | 2020-11-12 | 2022-05-19 | 深圳Tcl数字技术有限公司 | Overcurrent protection trigger circuit and device |
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Address after: 611731 No. 99, Tianquan Road, high tech Zone, Chengdu, Sichuan Patentee after: CHENGDU GREAT WALL DEVELOPMENT TECHNOLOGY Co.,Ltd. Address before: 611731 no.1218, Hezuo Road, high tech Zone (West District), Chengdu, Sichuan Province Patentee before: CHENGDU GREAT WALL DEVELOPMENT TECHNOLOGY Co.,Ltd. |
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| CP01 | Change in the name or title of a patent holder |
Address after: 611731 No. 99, Tianquan Road, high tech Zone, Chengdu, Sichuan Patentee after: Chengdu Great Wall Development Technology Co.,Ltd. Address before: 611731 No. 99, Tianquan Road, high tech Zone, Chengdu, Sichuan Patentee before: CHENGDU GREAT WALL DEVELOPMENT TECHNOLOGY Co.,Ltd. |