CN103579991A - Over-current protection circuit - Google Patents
Over-current protection circuit Download PDFInfo
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- CN103579991A CN103579991A CN201210266364.5A CN201210266364A CN103579991A CN 103579991 A CN103579991 A CN 103579991A CN 201210266364 A CN201210266364 A CN 201210266364A CN 103579991 A CN103579991 A CN 103579991A
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Abstract
The invention provides an over-current protection circuit which comprises a power supply conversion unit, a detection unit, an amplification unit and a comparison unit. The power supply conversion unit is used for providing a drive voltage for electronic equipment, the detection unit comprises a current sensing resistor and a current voltage detecting chip, the current sensing resistor is electrically connected with a power supply, the current voltage detecting chip is used for detecting the voltages of the two ends of the current sensing resistor, the amplification unit is electrically connected with the current voltage detecting chip and used for calculating and amplifying the voltage difference of the two ends of the current sensing resistor, the comparison unit is simultaneously and electrically connected with the amplification unit and the power supply conversion unit, and the comparison unit is used for comparing the amplified voltage difference with a preset voltage value, and the power supply conversion unit is enabled or not enabled according to a comparison result. The over-current protection circuit is high in precision, and improves the accuracy of over-current monitor.
Description
Technical field
The present invention relates to a kind of current foldback circuit.
Background technology
The power supply circuits of the DC equipment such as main frame, router mostly need overcurrent protection design, to protect DC equipment when electric current is undergone mutation.Current overcurrent protection design realizes by fuse is set mostly, when having the large electric current of power supply output to pass through, and the protection equipment thereby fuse fuses automatically.Yet fuse is accurate not to the detecting of electric current, be difficult to quantize.Meanwhile, fuse rating is unadjustable, and versatility is poor.
Summary of the invention
In view of above situation, be necessary to provide a kind of current foldback circuit of accurately detecting current.
A kind of current foldback circuit, it comprises power conversion unit, detecting unit, amplifying unit and comparing unit, this power conversion unit is used to an electronic equipment that driving voltage is provided, this detecting unit comprises current sensing resistor and current/voltage detecting chip, this current sensing resistor and a power supply are electrically connected, this current/voltage detecting chip is for the voltage at detecting current sensing resistor two ends, this amplifying unit and detecting voltage chip are electrically connected, for calculating the also voltage difference at amplified current sensing resistor two ends, this comparing unit is electrically connected with amplifying unit and power conversion unit simultaneously, this comparing unit is for comparing voltage difference and a predeterminated voltage value after amplifying, and enable or do not enable power conversion unit according to comparison result.
Above-mentioned current foldback circuit is by detecting unit detecting current; and then the voltage at measuring resistance two ends; and calculate the also voltage difference at amplified current sensing resistor two ends by amplifying unit; comparing unit is compared voltage difference and predeterminated voltage value after amplifying; to enable or not enable power conversion unit, and then protection electronic equipment.Current foldback circuit precision of the present invention is high, has improved the accuracy of overcurrent monitoring.
Accompanying drawing explanation
Fig. 1 is the module map of the current foldback circuit of better embodiment of the present invention;
Fig. 2 is the circuit diagram of current foldback circuit shown in Fig. 1.
Main element symbol description
| |
100 |
| |
10 |
| Fuse | |
| Detecting unit | |
| 20 | |
| Current/voltage detecting chip | U1 |
| Current sensing resistor | R |
| Current-limiting resistance | RL1、RL2 |
| Electric capacity | C |
| Enable pin | EN |
| The first detecting voltage pin | VINP |
| Second voltage detecting pin | VINM |
| Tertiary voltage detecting pin | VCC |
| The 4th detecting voltage pin | SNS |
| Transfer of data pin | SCL、SDA |
| |
30 |
| Amplifying |
40 |
| The first input pin | RS+ |
| The second input pin | RS- |
| Output pin | |
| Comparing unit | |
| 50 | |
| Comparator | U2 |
| Reference power source | P3V3 |
| Divider resistance | RD1、RD2 |
| The first resistance | R1 |
| The second resistance | R2 |
| The 3rd resistance | R3 |
| Pull-up resistor | R4 |
| First input end | I+ |
| The second input terminal | I- |
| Lead-out terminal | O |
| |
60 |
Following embodiment further illustrates the present invention in connection with above-mentioned accompanying drawing.
Embodiment
Refer to Fig. 1 and Fig. 2, the invention provides a kind of current foldback circuit 100, it is applied in the electronic equipments such as host computer, router (figure mark), protects electronic equipment during for current break at a power supply 10.This power supply 10 is used to current foldback circuit 100 that operating voltage is provided, and in the present embodiment, the voltage of these power supply 10 outputs is about 12V.
This current foldback circuit 100 comprises fuse F, detecting unit 20, data processing unit 30, amplifying unit 40, comparing unit 50 and power conversion unit 60.
This fuse F is electrically connected between power supply 10 and detecting unit 20, thereby for the protection electronic equipment that automatically fuses when having large electric current to pass through.
This detecting unit 20 is for detecting current value and the magnitude of voltage of power supply 10 outputs.This detecting unit 20 comprises current/voltage detecting chip U1, current sensing resistor R, current-limiting resistance RL1, RL2 and capacitor C.This current/voltage detecting chip U1 comprises enable pin EN, the first detecting voltage pin VINP, second voltage detecting pin VINM, tertiary voltage detecting pin VCC, the 4th detecting voltage pin SNS and transfer of data pin SCL, SDA.In the present embodiment, the resistance value of this current sensing resistor R is 0.002 ohm, to improve current detection accuracy.
This enable pin EN is electrically connected by fuse F and power supply 10, so that this current/voltage detecting chip U1 obtains operating voltage.This current sensing resistor R connects with fuse F, and this current-limiting resistance RL1, RL2 are parallel to the two ends of current sensing resistor R, and this capacitor C is electrically connected between current-limiting resistance RL1, RL2, and in parallel with current sensing resistor R.This first detecting voltage pin VINP is electrically connected at one end of current sensing resistor R by current-limiting resistance RL1, be electrically connected between current sensing resistor R and fuse F, this second voltage detecting pin set VINM is electrically connected at the other end of current sensing resistor R by current-limiting resistance RL2.So, this first detecting voltage pin set VINP and second voltage detecting pin VINM can detecting current sensing resistor R two ends voltage so that this current/voltage detecting chip U1 calculates the current value of the electric current of current flowing sensing resistor R according to the voltage at this current sensing resistor R two ends and the resistance value of current sensing resistor R.This tertiary voltage detecting pin VCC and the 4th detecting voltage pin SNS are electrically connected at respectively the two ends of current sensing resistor R, are respectively used to the voltage at detecting current sensing resistor R two ends.This transfer of data pin SCL, SDA and data processing unit 30 is electrically connected, and for current/voltage being detected to the current value of the electric current of the current flowing sensing resistor R that chip U1 calculates, is sent to data processing unit 30.In the present embodiment, this data processing unit 30 is central processing unit (Central Processing Unit, CPU), for quantizing this current value so that Real-Time Monitoring.
This amplifying unit 40 is for calculating the also voltage difference at amplified current sensing resistor R two ends.This amplifying unit 40 comprises the first input pin RS+, the second input pin RS-and output pin OUT.This first input pin RS+, the second input pin RS-are electrically connected with tertiary voltage detecting pin VCC and the 4th detecting voltage pin SNS respectively, to obtain respectively the magnitude of voltage at current sensing resistor R two ends.This amplifying unit 40 draws the voltage difference at current sensing resistor R two ends by the magnitude of voltage subtraction that the first input pin RS+ and the second input pin RS-are obtained, this amplifying unit 40 amplifies several times by this voltage difference simultaneously, and exports the voltage difference after this amplification by output pin OUT.
This comparing unit 50 is for the voltage difference after above-mentioned amplification and a predeterminated voltage value being carried out and right, and exports a control signal to control power conversion unit 60 according to comparison result.Particularly, this comparing unit 50 comprises comparator U2, reference power source P3V3, divider resistance RD1, RD2, the first resistance R 1, the second resistance R 2, the 3rd resistance R 3 and pull-up resistor R4.This comparator U2 comprises the sub-I+ of first input end, the second input terminal I-and lead-out terminal O.This divider resistance RD1, RD2 are series between reference power source P3V3 and ground.The sub-I+ of this first input end is electrically connected between divider resistance RD1, RD2 by the first resistance R 1, so, the value of the voltage of this reference power source P3V3 after divider resistance RD1, RD2 dividing potential drop is the magnitude of voltage of the sub-I+ of this first input end, is used as the described predeterminated voltage value of comparing unit 50 simultaneously.This second input terminal I-is electrically connected at the output pin OUT of amplifying unit 40 by the second resistance R 2, to receive the voltage difference after amplifying.The 3rd resistance R 3 is electrically connected between the sub-I+ of first input end and lead-out terminal O, and this lead-out terminal O is electrically connected by pull-up resistor R4 and reference power source P3V3.When the voltage difference after amplifying receiving when comparing unit 50 is greater than this predeterminated voltage value, these comparing unit 50 output first control signals (for example low level signal), when the voltage difference after amplifying receiving when comparing unit 50 is less than or equal to this predeterminated voltage value, these comparing unit 50 output second control signals (for example high level signal).
In the present embodiment, this power conversion unit 60 is DC-DC (DC-DC) module, is used to electronic equipment that driving voltage is provided.This power conversion unit 60 is electrically connected with the lead-out terminal O of comparing unit 50, enables or does not enable, so that electronic equipment continues or break-off under the control for the control signal in comparing unit 50 outputs.
Further illustrate the operation principle of this current foldback circuit 100 below:
When power supply 10 work, electric current flow to detecting unit 20 through fuse F, detecting unit 20 detects the voltage at current sensing resistor R two ends by the first detecting voltage pin set VINP and second voltage detecting pin VINM, and calculates the current value of the electric current of current flowing sensing resistor R with this.Thereafter, this transfer of data pin SCL, SDA are sent to data processing unit 30 by this current value, so that by these data processing unit 30 Real-Time Monitorings.In addition, this detecting unit 20 is also detected the voltage at pin VCC and the 4th detecting voltage pin SNS detecting current sensing resistor R two ends by tertiary voltage, make amplifying unit 40 obtain the magnitude of voltage at current sensing resistor R two ends, and calculate the voltage difference at current sensing resistor R two ends with this.This amplifying unit 40 exports comparing unit 50 to by output pin OUT after this voltage difference is amplified.This comparing unit 50 is compared the voltage difference after this amplification and predeterminated voltage value, if now the electric current of electronic equipment is excessive, this voltage difference will be greater than this predeterminated voltage value, make comparing unit 50 to power conversion unit 60 output the first control signals (as low level), to control power conversion unit 60, do not enable, and then control electronic equipment break-off.
Be appreciated that this fuse F also can automatically fuse when electric current is excessive, further to protect electronic equipment.
Claims (9)
1. a current foldback circuit, it is characterized in that: described current foldback circuit comprises power conversion unit, detecting unit, amplifying unit and comparing unit, this power conversion unit is used to an electronic equipment that driving voltage is provided, this detecting unit comprises current sensing resistor and current/voltage detecting chip, this current sensing resistor and a power supply are electrically connected, this current/voltage detecting chip is for the voltage at detecting current sensing resistor two ends, this amplifying unit and detecting voltage chip are electrically connected, for calculating the also voltage difference at amplified current sensing resistor two ends, this comparing unit is electrically connected with amplifying unit and power conversion unit simultaneously, this comparing unit is for comparing voltage difference and a predeterminated voltage value after amplifying, and enable or do not enable power conversion unit according to comparison result.
2. current foldback circuit as claimed in claim 1; it is characterized in that: described current/voltage detecting chip comprises the first detecting voltage pin and second voltage detecting pin; described the first detecting voltage pin and second voltage detecting pin are electrically connected at respectively the two ends of current sensing resistor; with the voltage at detecting current sensing resistor two ends, described detecting voltage chip calculates the current value of the electric current of current flowing sensing resistor according to the voltage at these current sensing resistor two ends and the resistance value of current sensing resistor.
3. current foldback circuit as claimed in claim 2; it is characterized in that: described current foldback circuit also comprises data processing unit; described current/voltage detecting chip also comprises transfer of data pin; described transfer of data pin and data processing unit are electrically connected, for the current value of the electric current of the current flowing sensing resistor calculating is sent to data processing unit.
4. current foldback circuit as claimed in claim 3, is characterized in that: described data processing unit is central processing unit, for quantizing this current value.
5. current foldback circuit as claimed in claim 1; it is characterized in that: described current/voltage detecting chip also comprises tertiary voltage detecting pin and the 4th detecting voltage pin; described tertiary voltage detecting pin and the 4th detecting voltage pin are electrically connected at respectively the two ends of current sensing resistor, with the voltage at detecting current sensing resistor two ends.
6. current foldback circuit as claimed in claim 5; it is characterized in that: described amplifying unit comprises the first input pin, the second input pin and output pin; this first input pin and the second input pin are electrically connected with tertiary voltage detecting pin and the 4th detecting voltage pin respectively; to obtain respectively the magnitude of voltage at current sensing resistor two ends, the voltage difference at the current sensing resistor two ends that described amplifying unit calculates is exported by output pin after amplifying.
7. current foldback circuit as claimed in claim 6, it is characterized in that: described comparing unit comprises comparator, reference power source and two divider resistances, described two divider resistances are series between reference power source and ground, described comparator comprises first input end, the second input terminal and lead-out terminal, described first input end is electrically connected between two divider resistances, the value of the voltage of described reference power source after two divider resistance dividing potential drops be the described predeterminated voltage value of unit as a comparison, described the second input terminal is electrically connected at the output pin of amplifying unit to receive the voltage difference after amplifying, described lead-out terminal and power conversion unit are electrically connected, when the voltage difference after amplifying receiving when comparing unit is greater than predeterminated voltage value, described comparing unit is exported the first control signal by lead-out terminal, when the voltage difference after amplifying receiving when comparing unit is less than or equal to predeterminated voltage value, described comparing unit is exported the second control signal by lead-out terminal.
8. current foldback circuit as claimed in claim 7; it is characterized in that: described power conversion unit is DC-DC module; when this power conversion unit receives the first control signal, described power conversion unit is controlled and is not enabled so that electronic equipment break-off.
9. current foldback circuit as claimed in claim 1, is characterized in that: described current foldback circuit also comprises fuse, and described fuse is electrically connected between power supply and detecting unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210266364.5A CN103579991A (en) | 2012-07-30 | 2012-07-30 | Over-current protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210266364.5A CN103579991A (en) | 2012-07-30 | 2012-07-30 | Over-current protection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN103579991A true CN103579991A (en) | 2014-02-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210266364.5A Pending CN103579991A (en) | 2012-07-30 | 2012-07-30 | Over-current protection circuit |
Country Status (1)
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|---|---|
| CN (1) | CN103579991A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107834535A (en) * | 2017-09-23 | 2018-03-23 | 江苏永动国骥网络科技股份有限公司 | The intelligent domestic appliance controller |
| CN112068687A (en) * | 2020-08-21 | 2020-12-11 | 苏州浪潮智能科技有限公司 | System for server accords with restricted power supply to external power supply |
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| CN101615845A (en) * | 2008-06-28 | 2009-12-30 | 中国矿业大学 | A kind of portable intrinsically safe power supply |
| CN101727136A (en) * | 2008-10-17 | 2010-06-09 | 联想(北京)有限公司 | Method for protecting main board of computer, computer and constituent elements of computer |
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| CN102339585A (en) * | 2010-07-19 | 2012-02-01 | 三星电机株式会社 | Apparatus for driving light emitting device with over-current and over-voltage protection |
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| CN107834535A (en) * | 2017-09-23 | 2018-03-23 | 江苏永动国骥网络科技股份有限公司 | The intelligent domestic appliance controller |
| CN112068687A (en) * | 2020-08-21 | 2020-12-11 | 苏州浪潮智能科技有限公司 | System for server accords with restricted power supply to external power supply |
| CN112068687B (en) * | 2020-08-21 | 2022-07-08 | 苏州浪潮智能科技有限公司 | System for server accords with restricted power supply to external power supply |
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Application publication date: 20140212 |