CN102780198A - Overcurrent protection circuit - Google Patents
Overcurrent protection circuit Download PDFInfo
- Publication number
- CN102780198A CN102780198A CN2011101219898A CN201110121989A CN102780198A CN 102780198 A CN102780198 A CN 102780198A CN 2011101219898 A CN2011101219898 A CN 2011101219898A CN 201110121989 A CN201110121989 A CN 201110121989A CN 102780198 A CN102780198 A CN 102780198A
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- circuit
- sampling
- load
- inductance
- current foldback
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Abstract
The invention provides an overcurrent protection circuit. The overcurrent protection circuit comprises a sampling inductor which is connected in series with a circuit load, wherein the sampling inductor comprises a control circuit at a first connecting end and a controlled switch; the first connecting end is connected with the sampling inductor and is used for outputting a cut-off signal when the voltage of the first connecting end is changed due to the overcurrent of the circuit load; and the controlled switch is connected between a power supply and the circuit load, and is connected with the output end of the control circuit. According to the overcurrent protection circuit, the current of the load is sampled by the sampling inductor, so that the burden of the circuit can be lightened effectively and the efficiency of the circuit can be improved effectively.
Description
Technical field
The invention belongs to circuit field, particularly a kind of current foldback circuit.
Background technology
In the various circuit, in order to protect power supply and load, set up and be equipped with current foldback circuit, and current foldback circuit the most commonly used all is to adopt sampling resistor to come the electric current of sample streams through circuit load.Like application number be: in the Chinese patent document of CN200520055098.7; A kind of overcurrent detecting device is provided; It comprises power supply, current sampling resistor, load and comparator, and wherein, current sampling resistor is connected with load with the sampling load current; And the current conversion after will sampling is to send into comparator behind the voltage, so that compare with reference voltage.When the load current overcurrent, the comparative voltage that inputs to comparator will increase, and thus, comparator will the outputting alarm signal.
Because this type of current foldback circuit all is to go up sampling resistor of extra increase in main current path (being the path of power supply to load); Utilize the voltage drop on the sample resistance to judge size of current; This increases extra burden can for the limited power supply of power, lowers efficiency.Therefore, how to address this problem, become the technical barrier that those skilled in the art need to be resolved hurrily in fact.
Summary of the invention
The object of the present invention is to provide the high current foldback circuit of a kind of efficient.
Reach other purposes in order to achieve the above object, current foldback circuit provided by the invention comprises: the sampling inductance of connecting with circuit load; The control circuit that comprises first link, said first link is connected with said sampling inductance, is used for output cut-off signal when the voltage of said first link changes because of said circuit load overcurrent; And be connected between power supply and the said circuit load and the controlled switch that is connected with said control circuit output.
As a kind of optimal way, said control circuit can comprise; The bleeder circuit that comprises said first tie point; The comparison circuit that is connected with said bleeder circuit.
As another kind of optimal way, said control circuit can also comprise; Second bleeder circuit that is connected with another input of the said sampling inductance other end and said comparison circuit.
As another optimal way, said control circuit can also comprise; Be used to drive the drive circuit of said controlled switch.
As another optimal way, said sampling inductance can be aluminium foil inductance or other inductance; Said controlled switch circuit can adopt triode as switch, also can adopt other controlled switchs, like metal-oxide-semiconductor etc.
In sum, current foldback circuit of the present invention adopts the sampling inductance to come circuital current is sampled, and compared to existing the sample mode of load current of sampling resistor that adopts, the present invention can effectively alleviate the burden of circuit, improves circuit efficiency.
Description of drawings
Fig. 1 is the basic structure sketch map of current foldback circuit of the present invention.
Fig. 2 is the embodiment sketch map of current foldback circuit of the present invention.
Embodiment
See also Fig. 1 and Fig. 2, current foldback circuit of the present invention comprises: sampling inductance, control circuit, and controlled switch circuit.
Said sampling inductance and circuit load are in series.As shown in Figure 2, sampling inductance L 1 and being connected between power supply (P10V) and the load R7.As a kind of optimal way, said sampling inductance L 1 can be an aluminium foil inductance etc.But, it should be appreciated by those skilled in the art that the sampling inductance is not to exceed with the aluminium foil inductance, in fact, the inductance of other any types all is feasible.
Said control circuit comprises first link, and said first link is connected with said sampling inductance, is used for output cut-off signal when the voltage of said first link changes because of said circuit load overcurrent.As a kind of optimal way, as shown in Figure 2, the first link V2 of said control circuit connects an end of sampling inductance L 1, and it comprises: first bleeder circuit, second bleeder circuit, and comparison circuit etc.Wherein, first bleeder circuit comprises: the resistance R 3 that is connected the first link V2; One end is connected with resistance R 3, the resistance R 4 of other end ground connection; The capacitor C parallelly connected with resistance R 4? Second bleeder circuit comprises: an end connects the resistance R 1 of an end of sampling inductance L 1; One end connects the other end of resistance R 1, the resistance R 2 of other end ground connection; The capacitor C parallelly connected with resistance R 2? Comparison circuit comprises: normal phase input end 3 connection resistance R 3, inverting input 2 are connected the comparator U1A (being AD8554) of resistance R 1 and R2 points of common connection; Be connected the capacitor C 1 between comparator U1A normal phase input end and the inverting input; Be connected resistance R 6.1 and R6.2 between comparator U1A normal phase input end 3 and the output 1.Wherein, resistance R 4 and R5, and capacitor C? The bleeder circuit that constitutes is used for the voltage V+ after the comparator U1A of comparison circuit provides sampling, so that compare with reference voltage Vref _ OC.In addition, said control circuit also comprises: an end connects the resistance R 5 of resistance R 3, other end connecting circuit fuse F1 one end and is used to drive the drive circuit of controlled switch.Said drive circuit comprises; Be connected the resistance R 10 of comparator U1A output 1; Base stage connects the transistor Q2 of resistance R 10, grounded emitter; Be connected the resistance R 8 of transistor Q2 collector electrode; The resistance R 9 of connecting with resistance R 8.
Said controlled switch is connected between power supply and the said circuit load, and is connected with said control circuit output.As shown in Figure 2, said controlled switch comprises: emitter connects the transistor Q1 of resistance R 9, collector electrode connection sampling inductance L 1, base stage connection resistance R 8 and R9 points of common connection.
The operation principle of foregoing circuit is following:
After circuit power is connected, because the existence of resistance R 5, so give higher bias voltage of V+ port of comparator U1A at the very start; And the voltage of the V-port of comparator U1A is zero, and so, the V+ port voltage is higher than the V-port voltage; So comparator U1A exports high level; Thereby 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 operate as normal, 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。
Circuit working just often, sampling inductance L 1 itself is to do the aluminium foil inductance to use, but when circuit generation over-current phenomenon avoidance; Because the existence of sampling inductance L 1 self internal resistance; The V2 terminal voltage of inductance L 1 of causing sampling reduces, and thus, causes the V+ terminal voltage of comparator U1A to reduce; So comparator U1A output low level, thereby impel transistor Q1 to turn-off.So just reached the effect of overcurrent protection.
Need to prove that above-mentioned Fig. 2 only just lists, but not be used to limit the present invention; It should be appreciated by those skilled in the art that control circuit, controlled switch are not to exceed with circuit shown in Figure 2, it can also be other circuit structure; For example, controlled switch can adopt relay, metal-oxide-semiconductor or the like.
In sum, current foldback circuit of the present invention can effectively alleviate the burden of power supply through adopting the sampling inductance but not sampling resistor, improves the efficient of circuit.
The foregoing description is just listed expressivity principle of the present invention and effect is described, but not is used to limit the present invention.Any personnel that are familiar with this technology all can make amendment to the foregoing description under spirit of the present invention and scope.Therefore, rights protection scope of the present invention should be listed like claims.
Claims (6)
1. current foldback circuit is characterized in that comprising:
The sampling inductance of connecting with circuit load;
The control circuit that comprises first link, said first link is connected with an end of said sampling inductance, is used for output cut-off signal when the voltage of said first link changes because of said circuit load overcurrent; Be connected between power supply and the said circuit load and the controlled switch that is connected with said control circuit output.
2. current foldback circuit as claimed in claim 1 is characterized in that: said control circuit comprises; First bleeder circuit that comprises said first tie point; The comparison circuit that one input is connected with said first bleeder circuit.
3. current foldback circuit as claimed in claim 2 is characterized in that: said control circuit also comprises; Second bleeder circuit that is connected with another input of the said sampling inductance other end and said comparison circuit.
4. like each described current foldback circuit of claim 1 to 3, it is characterized in that: said control circuit comprises; Be used to drive the drive circuit of said controlled switch.
5. current foldback circuit as claimed in claim 1 is characterized in that: said sampling inductance is the aluminium foil inductance.
6. current foldback circuit as claimed in claim 1 is characterized in that: said controlled switch comprises: transistor, metal-oxide-semiconductor, relay.
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 true CN102780198A (en) | 2012-11-14 |
| CN102780198B CN102780198B (en) | 2016-01-20 |
Family
ID=47125010
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110121989.8A Active CN102780198B (en) | 2011-05-12 | 2011-05-12 | Current foldback circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102780198B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN104779577A (en) * | 2014-01-10 | 2015-07-15 | 海洋王（东莞）照明科技有限公司 | Over-current protection circuit |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996014684A1 (en) * | 1994-11-02 | 1996-05-17 | Raychem Corporation | Solid state, resettable overcurrent protection device |
| JPH08275263A (en) * | 1995-03-29 | 1996-10-18 | Rinnai Corp | Overcurrent protection device |
| CN2359827Y (en) * | 1998-07-15 | 2000-01-19 | 王森成 | Induction type short-circuit-proof protector |
| CN2552008Y (en) * | 2002-01-21 | 2003-05-21 | 丰叶电器制造厂有限公司 | Alarm |
| CN101867289A (en) * | 2010-05-19 | 2010-10-20 | 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 |
-
2011
- 2011-05-12 CN CN201110121989.8A patent/CN102780198B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996014684A1 (en) * | 1994-11-02 | 1996-05-17 | Raychem Corporation | Solid state, resettable overcurrent protection device |
| JPH08275263A (en) * | 1995-03-29 | 1996-10-18 | Rinnai Corp | Overcurrent protection device |
| CN2359827Y (en) * | 1998-07-15 | 2000-01-19 | 王森成 | Induction type short-circuit-proof protector |
| CN2552008Y (en) * | 2002-01-21 | 2003-05-21 | 丰叶电器制造厂有限公司 | Alarm |
| CN101867289A (en) * | 2010-05-19 | 2010-10-20 | 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 |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779577A (en) * | 2014-01-10 | 2015-07-15 | 海洋王（东莞）照明科技有限公司 | Over-current protection circuit |
| 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 |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102780198B (en) | 2016-01-20 |
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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. |
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