CN102780198B - Current foldback circuit - Google Patents
Current foldback circuit Download PDFInfo
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- CN102780198B CN102780198B CN201110121989.8A CN201110121989A CN102780198B CN 102780198 B CN102780198 B CN 102780198B CN 201110121989 A CN201110121989 A CN 201110121989A CN 102780198 B CN102780198 B CN 102780198B
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Abstract
The invention provides a kind of current foldback circuit, it comprises: the sampling inductance of connecting with circuit load; Comprise the control circuit of the first link, described first link is connected with described sampling inductance, for exporting cut-off signal when the voltage of described first link changes because of described circuit load overcurrent; And be connected to the controlled switch be connected between power supply with described circuit load and with described control circuit output.Because the present invention utilizes sampling inductance to sample to load current, so effectively can alleviate the burden of circuit, improve the efficiency of circuit.
Description
Technical field
The invention belongs to circuit field, particularly a kind of current foldback circuit.
Background technology
In various circuit, in order to protection power source and load, set up and be equipped with current foldback circuit, and current foldback circuit the most conventional is all adopt sampling resistor to carry out the electric current of sample streams through circuit load.As application number is: in the Chinese patent literature of CN200520055098.7, provide a kind of overcurrent detecting device, it comprises power supply, current sampling resistor, load and comparator, wherein, current sampling resistor and load in series are with load current of sampling, and be send into comparator, to compare with reference voltage after voltage by the current conversion after sampling.When load current overcurrent, the comparative voltage inputing to comparator will increase, and thus, comparator will outputting alarm signal.
Because this type of current foldback circuit is all at main current path (namely power supply is to the path of a load) upper extra increase sampling resistor; utilize the voltage drop on sample resistance to judge size of current; this can increase extra burden to the power supply of power limited, lowers efficiency.Therefore, how to address this problem, become those skilled in the art's technical barrier urgently to be resolved hurrily in fact.
Summary of the invention
The object of the present invention is to provide the current foldback circuit that a kind of efficiency is high.
In order to achieve the above object and other objects, current foldback circuit provided by the invention, comprising: the sampling inductance of connecting with circuit load; Comprise the control circuit of the first link, described first link is connected with described sampling inductance, for exporting cut-off signal when the direct voltage of described first link changes because of described circuit load overcurrent; And be connected to the controlled switch be connected between DC power supply with described circuit load and with described control circuit output.
As a kind of optimal way, described control circuit can comprise; Comprise the first bleeder circuit of described first link; The comparison circuit be connected with described first bleeder circuit.
As another kind of optimal way, described control circuit can also comprise; The second bleeder circuit be connected with another input of the described sampling inductance other end and described comparison circuit.
As another optimal way, described control circuit can also comprise; For driving the drive circuit of described controlled switch.
As another optimal way, described sampling inductance can be aluminium foil inductance or other inductance; Described controlled switching circuit can adopt triode as switch, also can adopt other controlled switchs, as metal-oxide-semiconductor etc.
In sum, current foldback circuit of the present invention adopts sampling inductance to sample to circuital current, the mode of load current of sampling compared to existing employing sampling resistor, and the present invention effectively can alleviate the burden of circuit, improves circuit efficiency.
Accompanying drawing explanation
Fig. 1 is the basic structure schematic diagram of current foldback circuit of the present invention.
Fig. 2 is the embodiment schematic diagram of current foldback circuit of the present invention.
Embodiment
Refer to Fig. 1 and Fig. 2, current foldback circuit of the present invention comprises: sampling inductance, control circuit and controlled switching circuit.
Described sampling inductance and circuit load are in series.As shown in Figure 2, to sample inductance L 1 and being connected between power supply (P10V) and load R7.As a kind of optimal way, described sampling inductance L 1 can be aluminium foil inductance etc.But, it should be appreciated by those skilled in the art that sampling inductance is not limited with aluminium foil inductance, in fact, the inductance of other any types is all feasible.
Described control circuit comprises the first link, and described first link is connected with described sampling inductance, for exporting cut-off signal when the voltage of described first link changes because of described circuit load overcurrent.As a kind of optimal way, as shown in Figure 2, the first link V2 of described control circuit connects one end of sampling inductance L 1, and it comprises: the first bleeder circuit, the second bleeder circuit and comparison circuit etc.Wherein, the first bleeder circuit comprises: the resistance R3 being connected to the first link V2; One end is connected with resistance R3, the resistance R4 of other end ground connection; The electric capacity C in parallel with resistance R4? Second bleeder circuit comprises: one end connects the resistance R1 of one end of sampling inductance L 1; The other end of one end contact resistance R1, the resistance R2 of other end ground connection; The electric capacity C in parallel with resistance R2? Comparison circuit comprises: normal phase input end 3 contact resistance R3, inverting input 2 are connected to the comparator U1A (i.e. AD8554) of resistance R1 and R2 points of common connection; Be connected to the electric capacity C1 between comparator U1A normal phase input end and inverting input; Be connected to resistance R6.1 and R6.2 between comparator U1A normal phase input end 3 and output 1.Wherein, resistance R4 and R5 and electric capacity C? the bleeder circuit formed, for providing the V+ of the voltage after sampling to the comparator U1A of comparison circuit, to compare with reference voltage Vref _ OC.In addition, described control circuit also comprises: the resistance R5 of one end contact resistance R3, other end connecting circuit fuse F1 one end and for driving the drive circuit of controlled switch.Described drive circuit comprises; Be connected to the resistance R10 of comparator U1A output 1; The transistor Q2 of base stage contact resistance R10, grounded emitter; Be connected to the resistance R8 of transistor Q2 collector electrode; The resistance R9 connected with resistance R8.
Described controlled switch is connected between power supply and described circuit load, and is connected with described control circuit output.As shown in Figure 2, described controlled switch comprises: emitter contact resistance R9, collector electrode connect the transistor Q1 of sampling inductance L 1, base stage contact resistance R8 and R9 points of common connection.
The operation principle of foregoing circuit is as follows:
After circuit power is connected, due to the existence of resistance R5, so give the bias voltage that the V+ port one of comparator U1A is higher at the very start, and the voltage of the V-port of comparator U1A is zero, so, V+ port voltage is higher than V-port voltage, so comparator U1A exports high level, thus transistor Q2 saturation conduction, and then impel transistor Q1 conducting, so supply voltage is conducting to the right side of sampling inductance L 1.During normal work, the V1 terminal voltage of comparator U1AV+ port voltage, V-port voltage, sampling inductance L 1 is respectively:
V
1＝V
2+R
L·I
L。
When circuit working is normal, sampling inductance L 1 itself is do aluminium foil inductance to use, but when circuit generation over-current phenomenon avoidance, due to the existence of self internal resistance of sampling inductance L 1, cause the V2 terminal voltage of sampling inductance L 1 to reduce, thus, cause the V+ terminal voltage of comparator U1A to reduce, so comparator U1A output low level, thus transistor Q1 is impelled to turn off.So just reach the effect of overcurrent protection.
It should be noted that, above-mentioned Fig. 2 only just lists, but not for limiting the present invention, it should be appreciated by those skilled in the art that control circuit, controlled switch are not limited with circuit shown in Fig. 2, it can also be other circuit structure, such as, controlled switch can adopt relay, metal-oxide-semiconductor etc.
In sum, current foldback circuit of the present invention, by adopting sampling inductance but not sampling resistor, effectively can alleviate the burden of power supply, improves the efficiency of circuit.
Above-described embodiment only listing property illustrates principle of the present invention and effect, but not for limiting the present invention.Any person skilled in the art person all can without departing from the spirit and scope of the present invention, modify to above-described embodiment.Therefore, the scope of the present invention, should listed by claims.
Claims (2)
1. a current foldback circuit, is characterized in that comprising:
The sampling inductance of connecting with circuit load;
Comprise the control circuit of the first link, described first link is connected with one end of described sampling inductance, for exporting cut-off signal when the direct voltage of described first link changes because of described circuit load overcurrent;
Be connected to the controlled switch be connected between DC power supply with described circuit load and with described control circuit output;
Wherein, described control circuit also comprises the first bleeder circuit of described first link, the comparison circuit that one input is connected with described first bleeder circuit, the second bleeder circuit be connected with the described sampling inductance other end and another input of described comparison circuit, comparator is comprised in described comparison circuit, described comparator has positive input, reverse input end, the positive input of described comparator is connected with the first bleeder circuit, and the reverse input end of described comparator is connected with the second bleeder circuit;
For driving the drive circuit of controlled switch, comprising: transistor Q2, resistance R8 and R9, the base stage of described transistor Q2 is connected to comparator output terminal, grounded emitter; Resistance R8 connects with resistance R9;
Described controlled switch comprises the transistor Q1 of emitter contact resistance R9, base stage contact resistance R8 and described resistance R9 points of common connection, and during described circuit generation over-current phenomenon avoidance, described transistor Q1 turns off.
2. current foldback circuit as claimed in claim 1, is characterized in that: described sampling inductance is aluminium foil inductance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110121989.8A CN102780198B (en) | 2011-05-12 | 2011-05-12 | Current foldback circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110121989.8A CN102780198B (en) | 2011-05-12 | 2011-05-12 | Current foldback circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102780198A CN102780198A (en) | 2012-11-14 |
| CN102780198B true CN102780198B (en) | 2016-01-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110121989.8A Active CN102780198B (en) | 2011-05-12 | 2011-05-12 | Current foldback circuit |
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| Country | Link |
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| CN (1) | CN102780198B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779577B (en) * | 2014-01-10 | 2018-11-06 | 海洋王（东莞）照明科技有限公司 | A kind of current foldback circuit |
| CN104600677A (en) * | 2015-01-14 | 2015-05-06 | 常州格力博有限公司 | Short-circuit protection method for transistor in control circuit |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2359827Y (en) * | 1998-07-15 | 2000-01-19 | 王森成 | Induction type short-circuit-proof protector |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IL115797A0 (en) * | 1994-11-02 | 1996-01-19 | Raychem Corp | Solid state resettable overcurrent protection device |
| JP3277091B2 (en) * | 1995-03-29 | 2002-04-22 | リンナイ株式会社 | Overcurrent protection device |
| CN2552008Y (en) * | 2002-01-21 | 2003-05-21 | 丰叶电器制造厂有限公司 | Alarm device |
| CN101867289B (en) * | 2010-05-19 | 2012-05-30 | 杭州矽力杰半导体技术有限公司 | Switch power supply with constant voltage/constant current output and control method thereof |
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2011
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2359827Y (en) * | 1998-07-15 | 2000-01-19 | 王森成 | Induction type short-circuit-proof protector |
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| CN102780198A (en) | 2012-11-14 |
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Effective date of registration: 20170322 Address after: 518000 room C, building 202-207, No.1 building, No. six Nanshan District Road, Shenzhen, Guangdong, China Patentee after: Shenzhen Union Medical Technology Co., Ltd. Address before: 201203 Jiading Jiading District Industrial Zone, No. Pratt & Whitney Road, room 3, building 1098, room 333 Patentee before: Shanghai United Imaging Healthcare Co., Ltd. |