CN104882856A - High-precision over-current detection circuit - Google Patents
High-precision over-current detection circuit Download PDFInfo
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- CN104882856A CN104882856A CN201510274541.8A CN201510274541A CN104882856A CN 104882856 A CN104882856 A CN 104882856A CN 201510274541 A CN201510274541 A CN 201510274541A CN 104882856 A CN104882856 A CN 104882856A
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- amplifier
- mosfet pipe
- resistance
- operational amplifier
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Abstract
The invention discloses a high-precision over-current detection circuit. The circuit is characterized in that the circuit comprises a signal amplification circuit, a comparator circuit and a switch control circuit; the signal amplification circuit comprises an operational amplifier U1, a MOSFET pipe Q2 and a resistor R2; the comparator circuit comprises an operational amplifier U2 and a resistor R3; the switch control circuit comprises a triode Q3 and a resistor R4; an in-phase input end of the operational amplifier U1 is connected to an output end of a current detection resistor R1; a grid electrode of the MOSFET pipe Q2 is connected to an output end of the operational amplifier U1; a drain electrode of the MOSFET pipe Q2 is connected to the in-phase input end of the operational amplifier U1; an in-phase input end of the operational amplifier U2 is connected to a source electrode of the MOSFET pipe Q2; an antiphase input end of the operational amplifier U2 is connected to a reference voltage; a collector electrode of a transistor Q3 is connected to an oscillator port of a PWM controller. By using the over-current detection circuit, current detection precision is high; an over-current protection response speed is fast and simultaneously a current limit parameter of a working current can be flexibly adjusted.
Description
Technical field
The present invention relates to field of switch power, particularly a kind of high accuracy over-current detection circuit.
Background technology
Along with the development of power electronic technology, DC/DC Switching Power Supply progressively instead of linear power supply in fields such as industrial equipment, communication equipment, power equipments, obtains a wide range of applications.The power tube of Switching Power Supply is operated in the state of high frequency turn-on and turn-off, and input direct voltage is chopped into pulse voltage, and controller is by regulating the duty ratio of pwm pulse signal with regulated output voltage.Compare with linear power supply, Switching Power Supply has the advantages such as conversion efficiency is high, volume is little, lightweight.
Switching Power Supply must consider the protective circuit such as overcurrent, overvoltage in the design, and the real work parameter of circuit and design parameter are matched.When circuit breaks down, as short circuit or open circuit phenomenon appear in output, need protective circuit to stop the work of Switching Power Supply, with the power device of protection power source inside.If protecting circuit designed is bad, then fault will cause burning of Switching Power Supply, damages the equipment that power output end connects, and even dangerous phenomenons such as getting an electric shock or catch fire occurs.Therefore, the design of protective circuit is extremely important, directly affects the reliability of power work.
Conventional current foldback circuit as shown in Figure 1.The power MOSFET tube Q1 serial connection current-limiting resistance R1 that Switching Power Supply is elementary.During power work, detected the operating current of main primary by the voltage at current-limiting resistance two ends.Once the terminal voltage of resistance R1 exceedes set point, driving transistors Q2 conducting.The collector electrode of transistor Q2 connects the oscillator port of PWM power management chip, and Q2 conducting then drags down oscillator port, the output of powered-down.This protective circuit structure is simple, but over-current detection precision is low.The precision of current detecting is subject to the impact of the factor such as resistance precision, transistor base threshold voltage, and Current Limits flow valuve is fixed, and cannot adjust.How to improve the accuracy of detection of current foldback circuit, consider adjustable current limitation parameter simultaneously, the art of this patent launches research based on such background.
Summary of the invention
The object of the invention is to design a kind of high accuracy over-current detection circuit.
To achieve these goals, embodiments provide a kind of high accuracy over-current detection circuit, comprise a signal amplification circuit, a comparator circuit and an ON-OFF control circuit, wherein:
Described signal amplification circuit comprises operational amplifier U1, MOSFET pipe Q2 and resistance R2.
Described comparator circuit comprises operational amplifier U2 and resistance R3.
Described ON-OFF control circuit comprises triode Q3 and resistance R4.
Further, one end of the in-phase input end connecting resistance R2 of described amplifier U1; The reverse inter-input-ing ending grounding of described amplifier U1.
Further, the grid of described MOSFET pipe Q2 connects the output of amplifier U1; The drain electrode of described MOSFET pipe Q2 connects the in-phase input end of amplifier U1; One end of the source electrode connecting resistance R3 of described MOSFET pipe Q2.
Further, the in-phase input end of described amplifier U2 connects the source electrode of MOSFET pipe Q2; The anti-phase input termination reference voltage of described amplifier U2.
Further, one end of the base stage connecting resistance R4 of described transistor Q3; The output of another termination amplifier U2 of described resistance R4; The collector electrode of described transistor Q3 connects the oscillator port of PWM controller.
Further, described MOSFET pipe Q2 adopts N-channel MOS FET pipe.
Further, described triode Q3 adopts NPN type triode.
Embodiments provide a kind of high accuracy over-current detection circuit.The circuit realiration high precision test of working current value, can to adjust the cut-off current of power work electric current simultaneously easily by changing reference voltage value.Compared to the prior art, current foldback circuit accuracy of detection is high, and reaction speed is faster, can realize the flexible adjustment of current limliting maximum.
Accompanying drawing explanation
In order to make the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the present invention is described in further detail, wherein:
Fig. 1 is the schematic diagram of prior art current foldback circuit;
Fig. 2 is the schematic diagram of high accuracy over-current detection circuit of the present invention.
Embodiment
Below in conjunction with accompanying drawing, method of the present invention is described in further detail.
The schematic diagram of the high accuracy over-current detection circuit that Fig. 2 provides for the embodiment of the present invention.As shown in the figure, embodiments provide a kind of high accuracy over-current detection circuit, comprise a signal amplification circuit, a comparator circuit and an ON-OFF control circuit, wherein:
Described signal amplification circuit comprises operational amplifier U1, MOSFET pipe Q2 and resistance R2.
Described comparator circuit comprises operational amplifier U2 and resistance R3.
Described ON-OFF control circuit comprises triode Q3 and resistance R4.
Further, one end of the in-phase input end connecting resistance R2 of described amplifier U1; The reverse inter-input-ing ending grounding of described amplifier U1.
Further, the grid of described MOSFET pipe Q2 connects the output of amplifier U1; The drain electrode of described MOSFET pipe Q2 connects the in-phase input end of amplifier U1; One end of the source electrode connecting resistance R3 of described MOSFET pipe Q2.
Further, the in-phase input end of described amplifier U2 connects the source electrode of MOSFET pipe Q2; The anti-phase input termination reference voltage of described amplifier U2.
Further, one end of the base stage connecting resistance R4 of described transistor Q3; The output of another termination amplifier U2 of described resistance R4; The collector electrode of described transistor Q3 connects the oscillator port of PWM controller.
Further, described MOSFET pipe Q2 adopts N-channel MOS FET pipe.
Further, described triode Q3 adopts NPN type triode.
Over-current detection circuit in the embodiment of the present invention is made up of signal amplification circuit, comparator circuit and ON-OFF control circuit.Amplifier U1 makes the voltage at the voltage at resistance R2 two ends and resistance R1 two ends equal.The electric current flowing through resistance R2 also can flow through resistance R3, and the voltage generated at R3 two ends is:
Wherein I
infor main primary electric current.
Comparator U2 detects the terminal voltage of resistance R3, and reference voltage value U
refrelatively.Voltage when resistance R3 two ends is less than reference voltage, and comparator is closed, output low level; Once the terminal voltage of resistance R3 is greater than reference voltage, comparator exports high level, driving transistors Q3 conducting.The oscillator port of the collector electrode connecting valve power supply PWM controller of transistor Q3.After transistor Q3 conducting, the clock signal level of oscillator pin is dragged down, and PWM controller quits work, and the output of Switching Power Supply is closed, and completes overcurrent protection.Visible, the condition that overcurrent protection comparator is opened is:
U
RS＝U
ref
The reference voltage of input amplifier U2 inverting input determines the maximum of elementary operating current:
For the requirement of different protection parameters, by changing the reference voltage of input amplifier U3 in-phase end, can adjust the maximum limit flow valuve of primary current.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.
Claims (7)
1. a high accuracy over-current detection circuit, is characterized in that: comprise a signal amplification circuit, a comparator circuit and an ON-OFF control circuit; Described signal amplification circuit comprises operational amplifier U1, MOSFET pipe Q2 and resistance R2; Described comparator circuit comprises operational amplifier U2 and resistance R3; Described ON-OFF control circuit comprises triode Q3 and resistance R4.
2. drive circuit according to claim 1, is characterized in that: one end of the in-phase input end connecting resistance R2 of described amplifier U1; The reverse inter-input-ing ending grounding of described amplifier U1.
3. drive circuit according to claim 1, is characterized in that: the grid of described MOSFET pipe Q2 connects the output of amplifier U1; The drain electrode of described MOSFET pipe Q2 connects the in-phase input end of amplifier U1; One end of the source electrode connecting resistance R3 of described MOSFET pipe Q2.
4. drive circuit according to claim 1, is characterized in that: the in-phase input end of described amplifier U2 connects the source electrode of MOSFET pipe Q2; The anti-phase input termination reference voltage of described amplifier U2.
5. drive circuit according to claim 1, is characterized in that: one end of the base stage connecting resistance R4 of described transistor Q3; The output of another termination amplifier U2 of described resistance R4; The collector electrode of described transistor Q3 connects the oscillator port of PWM controller.
6. the drive circuit according to the arbitrary claim of claims 1 to 3, is characterized in that: described MOSFET pipe Q2 adopts N-channel MOS FET pipe.
7. the drive circuit according to the arbitrary claim of claim 1 to 5, is characterized in that: described triode Q3 adopts NPN type triode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510274541.8A CN104882856A (en) | 2015-05-25 | 2015-05-25 | High-precision over-current detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510274541.8A CN104882856A (en) | 2015-05-25 | 2015-05-25 | High-precision over-current detection circuit |
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| CN104882856A true CN104882856A (en) | 2015-09-02 |
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| CN201510274541.8A Pending CN104882856A (en) | 2015-05-25 | 2015-05-25 | High-precision over-current detection circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105929220A (en) * | 2016-04-19 | 2016-09-07 | 南京埃斯顿自动化股份有限公司 | Over-current detection circuit |
| CN106018934A (en) * | 2016-08-01 | 2016-10-12 | 国网福建省电力有限公司 | IGBT over-current detection circuit capable of adjusting over-current points continuously and realizing method thereof |
| CN111313392A (en) * | 2020-03-30 | 2020-06-19 | 浙江朗帝科技有限公司 | Automatic current-limiting protection system and method for crystal oscillator |
| CN111323634A (en) * | 2018-12-15 | 2020-06-23 | 深圳市角度控光智能照明技术有限公司 | Novel wide-range current sampling circuit |
| CN111884489A (en) * | 2019-05-03 | 2020-11-03 | 台达电子工业股份有限公司 | Power circuit and drive circuit |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201937235U (en) * | 2010-12-17 | 2011-08-17 | 西安奇维测控科技有限公司 | Overcurrent protection circuit |
| CN201937460U (en) * | 2010-12-07 | 2011-08-17 | 北大方正集团有限公司 | Stabilized voltage supply |
| CN102208802A (en) * | 2010-06-29 | 2011-10-05 | 上海山景集成电路技术有限公司 | Power switching tube overcurrent detection and overcurrent protection circuit |
| CN202906446U (en) * | 2012-10-31 | 2013-04-24 | 冠捷显示科技（厦门）有限公司 | Low-loss power output over-current protection circuit |
| CN204156500U (en) * | 2014-10-10 | 2015-02-11 | 深圳市英威腾电气股份有限公司 | Overcurrent-overvoltage protecting circuit |
-
2015
- 2015-05-25 CN CN201510274541.8A patent/CN104882856A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102208802A (en) * | 2010-06-29 | 2011-10-05 | 上海山景集成电路技术有限公司 | Power switching tube overcurrent detection and overcurrent protection circuit |
| CN201937460U (en) * | 2010-12-07 | 2011-08-17 | 北大方正集团有限公司 | Stabilized voltage supply |
| CN201937235U (en) * | 2010-12-17 | 2011-08-17 | 西安奇维测控科技有限公司 | Overcurrent protection circuit |
| CN202906446U (en) * | 2012-10-31 | 2013-04-24 | 冠捷显示科技（厦门）有限公司 | Low-loss power output over-current protection circuit |
| CN204156500U (en) * | 2014-10-10 | 2015-02-11 | 深圳市英威腾电气股份有限公司 | Overcurrent-overvoltage protecting circuit |
Non-Patent Citations (2)
| Title |
|---|
| 冯全源: "BUCK型DC-DC的电流检测电路设计", 《万方硕士学位论文库》 * |
| 周鹰: "用于声致发光的大功率超声驱动功率放大器的设计", 《CNKI中国优秀硕士学位论文库》 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105929220A (en) * | 2016-04-19 | 2016-09-07 | 南京埃斯顿自动化股份有限公司 | Over-current detection circuit |
| CN106018934A (en) * | 2016-08-01 | 2016-10-12 | 国网福建省电力有限公司 | IGBT over-current detection circuit capable of adjusting over-current points continuously and realizing method thereof |
| CN106018934B (en) * | 2016-08-01 | 2019-02-22 | 国网福建省电力有限公司 | A kind of continuously adjustable crosses the IGBT over-current detection circuit and its implementation of flow point |
| CN111323634A (en) * | 2018-12-15 | 2020-06-23 | 深圳市角度控光智能照明技术有限公司 | Novel wide-range current sampling circuit |
| CN111323634B (en) * | 2018-12-15 | 2022-04-05 | 深圳市角度控光智能照明技术有限公司 | Wide-range current sampling circuit |
| CN111884489A (en) * | 2019-05-03 | 2020-11-03 | 台达电子工业股份有限公司 | Power circuit and drive circuit |
| CN111884489B (en) * | 2019-05-03 | 2022-03-11 | 台达电子工业股份有限公司 | Power circuit and drive circuit |
| CN111313392A (en) * | 2020-03-30 | 2020-06-19 | 浙江朗帝科技有限公司 | Automatic current-limiting protection system and method for crystal oscillator |
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Application publication date: 20150902 |
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