CN107404219A - Current-limiting circuit and method and Switching Power Supply - Google Patents
Current-limiting circuit and method and Switching Power Supply Download PDFInfo
- Publication number
- CN107404219A CN107404219A CN201710767185.2A CN201710767185A CN107404219A CN 107404219 A CN107404219 A CN 107404219A CN 201710767185 A CN201710767185 A CN 201710767185A CN 107404219 A CN107404219 A CN 107404219A
- Authority
- CN
- China
- Prior art keywords
- current
- circuit
- resistor
- limiting circuit
- operational amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
Abstract
The invention discloses a kind of current-limiting circuit and method and Switching Power Supply.Current-limiting circuit, including：Operational amplifier, first resistor and switch element；The first input end of the operational amplifier receives the first current signal, and the first input end is grounded through the first resistor, the first current signal can be characterized by reading the pressure drop in the first resistor, second input of the operational amplifier receives the first reference voltage signal, the operational amplifier output terminal output current limiting judges signal, and the output end is connected with the switch element；When the current limliting judges that characterization needs to carry out current limliting, then the switching elements conductive is controlled, to carry out current limliting.Present invention improves circuit existing for prior art it is more complicated, need compared with multicomponent device the shortcomings that, complete in same circuit while realize two functions of reading and current limliting of electric current.
Description
Technical field
The present invention relates to electric and electronic technical field, in particular, is related to a kind of current-limiting circuit and method and switch electricity
Source.
Background technology
In many application scenarios, it is necessary to know the current value in circuit, also, property due to component and prevent from overloading
Etc. reason, it is necessary to being limited by the electric current of circuit.Prior art is usually to be respectively completed electric current using two circuits
Read and two functions of current limliting.
Integrated circuit refers to the element such as the transistor needed for a circuit, resistance, electric capacity and inductance and wiring to be mutually connected
Together, then it is integrated in again on a slight chip.And the chip of integrated circuit is smaller, often product is had more
Competitiveness.It is clear that in integrated circuits, if electric current reading and current-limiting function can be completed with a circuit, it can make
Obtain circuit and take less chip space, be possibly realized so that chip is smaller, while can also improve electric in the prior art
The shortcomings that more complicated and needs on road are compared with multicomponent device.
The content of the invention
In view of this, the present invention proposes a kind of current-limiting circuit and method and Switching Power Supply.In same circuit, Ke Yitong
Two functions of reading and current limliting of Shi Shixian electric currents, for solving, circuit existing for prior art is more complicated, it is more polynary to need
The problem of device.
The invention provides a kind of current-limiting circuit, including：Operational amplifier, first resistor and switch element；
The first input end of the operational amplifier receives the first current signal, and the first input end is through described first
Resistance eutral grounding, the pressure drop in the first resistor are used to characterize the first current signal,
Second input of the operational amplifier receives the first reference voltage signal, and the operational amplifier output terminal is defeated
Go out current limliting and judge signal, and the output end is connected with the switch element；
When the current limliting judges that characterization needs to carry out current limliting, then the switching elements conductive is controlled, to be limited
Stream.
Optionally, when the pressure drop on by the first resistor reaches first reference voltage signal, the current limliting
Judge that characterization needs to carry out current limliting, the switching elements conductive, start current limliting.
Optionally, cut-off current is the ratio of first reference voltage signal and the first resistor, and can be by changing
Become the size of first reference voltage signal or the resistance of the first resistor to change cut-off current.
Optionally, the first input end of the operational amplifier is connected with detection circuit, and the detection circuit, which receives, to be needed
Electric current in detection and current-limiting circuit is output to the first input end of the operational amplifier as the first current signal.
Optionally, the current-limiting circuit also includes current control circuit, the described electric current control of described switch element connection
Circuit processed, electric current is adjusted by the current control circuit to realize current limliting.
Optionally, the operational amplifier and switch element are integrated in chip, then described operational amplifier first is defeated
Enter the common port of end and the first resistor as the first pin, there is first pin electric current to read the multiplexing work(with current limliting
Energy.
Present invention also offers another current-limiting circuit, including：Described in two or more above-mentioned any one
Current-limiting circuit, in the current-limiting circuit described in two or more described, each the first described current signal is difference
The first current signal, each described current limliting judges that having one to characterize in signal needs to carry out current limliting, then so that opening accordingly
Element conductive is closed, to carry out current limliting.
The present invention also provides a kind of current-limiting method, based on any of the above current-limiting circuit of one, including：
It will be compared by the pressure drop of the first resistor and first reference voltage signal,
When being less than first reference voltage signal by the pressure drop of the first resistor, the current-limiting circuit circuit is only
Complete the function that electric current is read；
When the pressure drop by the first resistor reaches first reference voltage signal, the current limliting judges signal table
Sign needs to carry out current limliting, switching elements conductive, starts current limliting.
Present invention also offers a kind of Switching Power Supply, including power stage circuit and a kind of current limliting described in any of the above one
Circuit, first current signal are the electric current that measurement and current limliting are needed in the power stage circuit.
Optionally, the output end of the switch element is connected to the output end of error amplifier in the power stage circuit,
The first input end of the error amplifier receives the output feedback voltage of the power stage circuit, and the of the error amplifier
Two inputs receive the second reference voltage signal.
Compared with prior art, the technical scheme of the present invention has advantages below：In the present invention, the first of operational amplifier
Input introduces the first current signal and is grounded by the first resistor, is then characterized by the pressure drop for reading the first resistor
First current signal；Another input of operational amplifier receives the first reference voltage signal, the first described reference voltage
Signal and the ratio of the first resistor are then the maximum current value of current limliting；When first current signal is more than the cut-off current
When, switching elements conductive, carry out current limliting.The present invention is completed using a small amount of elements such as operational amplifier, resistance and switch elements
Electric current is read and current limliting two functions, so improve the more complicated of circuit and using component it is more the problem of.
Brief description of the drawings
Fig. 1 is the structural representation of current-limiting circuit of the present invention；
Fig. 2 is the structural representation containing two current-limiting circuits in circuit of the present invention；
Fig. 3 is the structural representation of current-limiting circuit embodiment of the present invention；
Embodiment
The preferred embodiments of the present invention are described in detail below in conjunction with accompanying drawing, but the present invention is not restricted to these
Embodiment.The present invention covers any replacement made in the spirit and scope of the present invention, modification, equivalent method and scheme.
Thoroughly understand in order that the public has to the present invention, be described in detail in present invention below preferred embodiment specific
Details, and description without these details can also understand the present invention completely for a person skilled in the art.
More specifically description is of the invention by way of example referring to the drawings in the following passage.It should be noted that accompanying drawing is adopted
Non- accurately ratio is used with more simplified form and, only to convenience, lucidly aid in illustrating the embodiment of the present invention
Purpose.
As shown in figure 1, the structural representation of current-limiting circuit is given, including：First resistor R, operational amplifier U1, switch
Element, current limiting measures.Described current-limiting circuit is connected with detection circuit.It will need to detect and the circuit of current limliting be referred to as main circuit,
By the circuit that detects by the electric current I in main circuitinThe first input end of the operational amplifier U1 is incorporated into, and the end passes through
The first resistor R ground connection, the second input of the operational amplifier U1 receive the first reference voltage signal Vm, computing
Amplifier U1 output end connects one end of the switch element, the other end connection transmission of electricity flow control electricity of the switch element
Road.
Main circuit in Fig. 1 is Buck circuits, and Iin is the inductive current of the Buck circuits detected, it is emphasized that,
Although the main circuit in Fig. 1 is Buck circuits, it is not limited only to apply in Buck circuits here, can is arbitrary
Power stage circuit.
The common port of the first resistor and the operational amplifier first input end is designated as A points, the voltage is designated as
VA, then circuit in Fig. 1 complete following function：
Work as VA＜ VmWhen, the switch element is not turned on, and now circuit obtains electricity by reading the magnitude of voltage of A points in Fig. 1
Flow IinValue.
Work as VA=VmWhen, the switching elements conductive, starting current control circuit, now, circuit in Fig. 1 not only can be with
Read electric current IinValue, and complete current-limiting function.
It can be seen that in Fig. 1 circuit current limliting maximum current value ImaxFor：
, can be by setting the first different reference voltage signal V in practical application scenemTo change the maximum of current limliting
Current value.
When the circuit in Fig. 1 is integrated circuit, A points are a pin A of chip, at any time, can pass through survey
Amount pin A magnitude of voltage reads current value of any time by main circuit, and works as VA=VmWhen, the switch element is led
It is logical, start to carry out main circuit current limliting, therefore pin here is multiplexing, can not only read main circuit current value can also be right
It carries out current limliting.
The maximum current value allowed by main circuit is set here with operational amplifier U1, to what is passed through in main circuit
Electric current is limited；And introduce the electric current I by main circuit in operational amplifier U1 one endin, and the end is through the described first electricity
Resistance ground connection, obtains the current value by primary circuit, so that circuit can in Fig. 1 by reading the voltage on first resistor R
To complete electric current reading and two functions of current limliting, reach the purpose of pin A multiplexings.
Some power stage circuits have the conduction mode of more than two or two-way in the different periods, to the power stage
When the electric current of circuit is read out with current limliting, then need to its per conduction mode all the way in electric current be read out and current limliting.Fig. 2
Shown four on-off circuits, the circuit are usually the circuit turn-on mode for having two-way, and circuit read functions are carried in Fig. 2
Current-limiting circuit by what is formed described in 2 Fig. 1 with circuit read functions and current-limiting circuit, this 2 circuits connect respectively
Input and the output current of four on-off circuits are received, the output of its operational amplifier is all connected to current control circuit.That is, four
When any electric current all the way is more than cut-off current in on-off circuit, current control circuit can carry out current limliting.Pin A in Fig. 2 and
Pin B is multiplexing pins.
Fig. 2 simply show the situation for needing the current-limiting circuit with circuit read functions described in two Fig. 1, if but main
Circuit needs the current-limiting circuit with circuit read functions described in any Fig. 1 within the scope of the present invention.
As shown in figure 3, illustrate a kind of embodiment of current-limiting circuit.Described switch element is switching tube M1, switching tube M1
For p-type metal-oxide-semiconductor, the output end connecting valve pipe M1 of operational amplifier U1 grid, the grounded drain of the switching tube M1,
Described current control circuit is the output end that the source electrode of Switching Power Supply is connected to main circuit Voltage loop.The Voltage loop is by transporting
Amplifier U2 compositions are calculated, U2 first input end receives the sampled signal of main circuit output voltage, and U2 the second input receives
Second reference voltage signal.Remainder is identical with Fig. 1.Main circuit described in Fig. 3 is Buck circuits.
Similarly, Fig. 3 circuit completes following function：
Work as VA＜ VmWhen, switching tube M1 is not turned on, and now circuit obtains electric current by reading the magnitude of voltage of A points in Fig. 1
IinValue, only complete electric current read functions.
Work as VA=VmWhen, switching tube M1 conductings, U2 output is directly dragged down, reduces the bias voltage of main circuit so that main electricity
Electric current in road receives limitation, is unlikely to excessive.Now, the circuit in Fig. 1 can not only read electric current Iin value, and complete
Into current-limiting function.
Embodiments described above, the restriction to the technical scheme protection domain is not formed.It is any in above-mentioned implementation
Modifications, equivalent substitutions and improvements made within the spirit and principle of mode etc., should be included in the protection model of the technical scheme
Within enclosing.
Claims (10)
- A kind of 1. current-limiting circuit, it is characterised in that including：Operational amplifier, first resistor and switch element；The first input end of the operational amplifier receives the first current signal, and the first input end is through the first resistor It is grounded, the pressure drop in the first resistor is used to characterize the first current signal,Second input of the operational amplifier receives the first reference voltage signal, the operational amplifier output terminal output limit Stream judges signal, and the output end is connected with the switch element；When the current limliting judges that characterization needs to carry out current limliting, then the switching elements conductive is controlled, to carry out current limliting.
- 2. current-limiting circuit according to claim 1, it is characterised in that：Pressure drop on by the first resistor reaches institute When stating the first reference voltage signal, the current limliting judges that characterization needs to carry out current limliting, the switching elements conductive, starts limit Stream.
- 3. current-limiting circuit according to claim 1, it is characterised in that：Cut-off current is first reference voltage signal and institute The ratio of first resistor is stated, and the resistance for the size or the first resistor for changing first reference voltage signal can be passed through Value changes cut-off current.
- 4. current-limiting circuit according to claim 1, it is characterised in that：The first input end of the operational amplifier is connected with Circuit is detected, the detection circuit, which receives, needs the electric current in detection and current-limiting circuit to be output to institute as the first current signal State the first input end of operational amplifier.
- 5. current-limiting circuit according to claim 1, it is characterised in that：The current-limiting circuit also includes current control circuit, The described current control circuit of described switch element connection, adjusts electric current to realize current limliting by the current control circuit.
- 6. according to the current-limiting circuit described in claim 1-5 any one, it is characterised in that：The operational amplifier and switch member Part is integrated in chip, then described operational amplifier first input end and the common port of the first resistor draw as first There is electric current to read the multiplexing function with current limliting for pin, first pin.
- A kind of 7. current-limiting circuit, it is characterised in that including：Described in two or more claims 1-6 any one Current-limiting circuit, in the current-limiting circuit described in two or more described, each the first described current signal is difference The first current signal, each described current limliting judges that having one to characterize in signal needs to carry out current limliting, then so that opening accordingly Element conductive is closed, to carry out current limliting.
- A kind of 8. current-limiting method, based on the current-limiting circuit described in 1-7 any one, it is characterised in that including：It will be compared by the pressure drop of the first resistor and first reference voltage signal,When being less than first reference voltage signal by the pressure drop of the first resistor, the current-limiting circuit circuit is only completed The function that electric current is read；When the pressure drop by the first resistor reaches first reference voltage signal, the current limliting judges that characterization needs Current limliting is carried out, switching elements conductive, starts current limliting.
- A kind of 9. Switching Power Supply, it is characterised in that including：Described in power stage circuit and claim 1-6 or 7 any one Current-limiting circuit, first current signal are the electric current that measurement and current limliting are needed in the power stage circuit.
- 10. Switching Power Supply according to claim 9, it is characterised in that：The output end of the switch element is connected to described The output end of error amplifier in power stage circuit, the first input end of the error amplifier receive the power stage circuit Feedback voltage is exported, the second input of the error amplifier receives the second reference voltage signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710767185.2A CN107404219A (en) | 2017-08-30 | 2017-08-30 | Current-limiting circuit and method and Switching Power Supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710767185.2A CN107404219A (en) | 2017-08-30 | 2017-08-30 | Current-limiting circuit and method and Switching Power Supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN107404219A true CN107404219A (en) | 2017-11-28 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710767185.2A Pending CN107404219A (en) | 2017-08-30 | 2017-08-30 | Current-limiting circuit and method and Switching Power Supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109962607A (en) * | 2017-12-26 | 2019-07-02 | 维谛公司 | A kind of Current limited Control adjusting method and device |
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|---|---|---|---|---|
| US6608520B1 (en) * | 2001-06-25 | 2003-08-19 | Texas Instruments Incorporated | Regulator circuit |
| JP2004045305A (en) * | 2002-07-15 | 2004-02-12 | Mitsubishi Electric Corp | Overcurrent detecting circuit |
| US20110279930A1 (en) * | 2010-05-17 | 2011-11-17 | Richpower Microelectronic Corporation | Switching regulator control circuit |
| CN103701312A (en) * | 2013-12-29 | 2014-04-02 | 上海艾为电子技术有限公司 | Current limiting circuit and method of boost converter |
| US20140097811A1 (en) * | 2012-10-05 | 2014-04-10 | Anpec Electronics Corporation | Current-limit system and method |
| CN104734477A (en) * | 2013-12-19 | 2015-06-24 | 李永红 | Output current limiting circuit and method |
-
2017
- 2017-08-30 CN CN201710767185.2A patent/CN107404219A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6608520B1 (en) * | 2001-06-25 | 2003-08-19 | Texas Instruments Incorporated | Regulator circuit |
| JP2004045305A (en) * | 2002-07-15 | 2004-02-12 | Mitsubishi Electric Corp | Overcurrent detecting circuit |
| US20110279930A1 (en) * | 2010-05-17 | 2011-11-17 | Richpower Microelectronic Corporation | Switching regulator control circuit |
| US20140097811A1 (en) * | 2012-10-05 | 2014-04-10 | Anpec Electronics Corporation | Current-limit system and method |
| CN104734477A (en) * | 2013-12-19 | 2015-06-24 | 李永红 | Output current limiting circuit and method |
| CN103701312A (en) * | 2013-12-29 | 2014-04-02 | 上海艾为电子技术有限公司 | Current limiting circuit and method of boost converter |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109962607A (en) * | 2017-12-26 | 2019-07-02 | 维谛公司 | A kind of Current limited Control adjusting method and device |
| CN109962607B (en) * | 2017-12-26 | 2020-10-02 | 维谛公司 | Current limiting control adjusting method and device |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Applicant before: JOULWATT TECHNOLOGY Inc.,Ltd. |