CN207586404U - Abnormal detection circuit and Switching Power Supply - Google Patents
Abnormal detection circuit and Switching Power Supply Download PDFInfo
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- CN207586404U CN207586404U CN201720723707.4U CN201720723707U CN207586404U CN 207586404 U CN207586404 U CN 207586404U CN 201720723707 U CN201720723707 U CN 201720723707U CN 207586404 U CN207586404 U CN 207586404U
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Abstract
The utility model discloses a kind of abnormal detection circuit and Switching Power Supplies.The exception refers to the exception of switch power source output voltage sampling end.Abnormal detection circuit includes filter circuit and comparator; characterize the second voltage of the filtered rear output characterization output voltage of first voltage of output voltage; the voltage sampling signal of the signal and characterization output voltage of the second voltage will be characterized; it is compared; output abnormality judges signal; when the exception judges that characterization is abnormal, abnormal protection is carried out.Switching Power Supply includes：Master power switch pipe, continued flow tube, inductance and abnormal detection circuit.The utility model overcomes the shortcomings that prior art, can effectively reduce the possibility of erroneous judgement, improves the reliability of product.
Description
Technical field
The utility model is related to power electronics field, more specifically, being related to a kind of abnormal detection circuit and switch
Power supply.
Background technology
In Switching Power Supply, it is often necessary to the output voltage of the Switching Power Supply is sampled, as feedback signal, according to the electricity
Pressure value is determined how to load supplying.Generally in the output terminal of Switching Power Supply, there are output voltage sampling end, the electricity of the sampling end
It is a definite value to be pressed under circuit normal condition, the output voltage that user can be needed by changing the resistance value of resistance.Together
When Switching Power Supply by the use of the voltage of the sampling end as feedback signal determine how to load be powered.Once the sampling end is sent out
Raw abnormal, the voltage value sampled is zero, and Switching Power Supply can enhance the power supply to load always so that output voltage increases,
The normal power supply of load is influenced, therefore, it is necessary to carry out abnormal protection.
In the prior art, judge whether the sampling end is abnormal generally by current method is introduced, that is, pass through
Electric current is introduced at the sampling end, and then detects the voltage value at sampling end to judge whether pin is abnormal, and then takes exception
Safeguard measure, but there is erroneous judgement in this method.Buck power supplys as shown in Figure 1, wherein FB points are the sampling end of chip, should
The voltage of sampling end can characterize the output voltage of the Switching Power Supply.The prior art is to introduce electric current I in FB points, passes through detection
The voltage value of FB, if VFB=0, then R2 short circuits, so that it is determined that FB points are abnormal, and then take abnormal protection measure.But there are two types of feelings
Condition can cause FB points abnormal, R2 short circuits or R1 open circuits.And above-mentioned introducing current method can only determine the situation when R2 short circuits, and
FB points caused by cannot detecting R1 open circuits are abnormal, therefore the prior art has erroneous judgement.
Utility model content
In view of this, the utility model proposes a kind of abnormal detection circuit and Switching Power Supplies, are deposited for solving the prior art
Appearance exception erroneous judgement, the technical issues of reliability is not high.
The utility model provides a kind of abnormal detection circuit, including：
Filter circuit receives the first voltage of characterization output voltage, and the second electricity of characterization output voltage is exported after filtered
Pressure；
Comparator, first input end receive the signal for characterizing the second voltage, and it is defeated that the second input terminal receives characterization
Go out the voltage sampling signal of voltage, the comparator output abnormality judges signal；
When the exception judges that characterization is abnormal, then abnormal protection is carried out.
Optionally, when the signal for characterizing the second voltage is less than the voltage sampling signal of the characterization output voltage,
The exception judges characterization normal operating conditions, when the signal for characterizing the second voltage is more than the characterization output voltage
Voltage sampling signal when, it is described abnormal to judge that characterization is abnormal.
Optionally, the abnormal detection circuit further includes bleeder circuit, the input terminal and filtered electrical of the bleeder circuit
The output terminal connection on road, the output terminal of bleeder circuit are connect with the first input end of the comparator, the bleeder circuit output
The signal of the characterization second voltage after partial pressure, as tertiary voltage, the tertiary voltage is as described in the characterization
The signal of second voltage.
Optionally, the exception refers to the exception of switch power source output voltage sampling end.
Optionally, in normal operation, the second voltage and the ratio of the tertiary voltage are more than switching circuit
Output voltage and the voltage sampling signal ratio.
Optionally, the first voltage of the characterization output voltage refers to, master power switch pipe and continued flow tube in Switching Power Supply
The voltage of common end.
The utility model also provides a kind of Switching Power Supply, including master power switch pipe, continued flow tube, inductance and any of the above one
Kind abnormal detection circuit, the master power switch pipe are connect with the continued flow tube, and common end is connect with described inductance one end,
The other end of inductance is output terminal；Filter circuit and master power switch pipe and the continued flow tube in the abnormal detection circuit
Common end connection.
Compared with prior art, the technical solution of the utility model has the following advantages：The utility model utilizes and characterizes institute
The output sampled signal of signal and the characterization output voltage for stating second voltage is compared, to judge whether sampling end occurs
It is abnormal.The utility model can not only detect that caused sampling end is abnormal during resistive short, when can also detect resistance interruption
Caused sampled point is abnormal, the possibility of erroneous judgement is reduced, so as to improve the reliability of product.
Description of the drawings
Fig. 1 is the part-structure schematic diagram of prior art abnormal detection circuit and Switching Power Supply；
Fig. 2 is the part-structure schematic diagram of the utility model abnormal detection circuit and Switching Power Supply；
Specific embodiment
The preferred embodiment of the utility model is described in detail, but the utility model is not merely below in conjunction with attached drawing
It is limited to these embodiments.The utility model covers any replacement made in the spirit and scope of the utility model, modification, equivalent
Method and scheme.
In order to which the public is made to have thorough understanding to the utility model, in following the preferred embodiment in the utility model specifically
Understand concrete details, and description without these details can also understand that this practicality is new completely for a person skilled in the art
Type.
The utility model is more specifically described by way of example with reference to attached drawing in the following passage.It should be noted that attached drawing
Using more simplified form and using non-accurate ratio, only to it is convenient, lucidly aid in illustrating the utility model
The purpose of embodiment.
In Switching Power Supply, it is often necessary to the output voltage of the Switching Power Supply is sampled, as feedback signal, according to the electricity
Pressure value is determined how to load supplying.In practical major applications, in the output terminal of Switching Power Supply, there are output voltage samplings
End is determined how by the use of the voltage of the sampling end as feedback signal and load is powered.
As shown in Fig. 2, the utility model abnormal detection circuit and a kind of circuit structure of Switching Power Supply are illustrated, it is described
Switching Power Supply is Buck circuits, including：First switch pipe M1 and second switch pipe M2, inductance L1 and capacitance C.First resistor R1 and
Second resistance R2 forms sample circuit, and output voltage is sampled.The drain electrode of the first switch pipe M1 connects input voltage,
The source electrode of the first switch pipe M1 connects the drain electrode of the second switch pipe M2, and the source electrode of the second switch pipe M2 connects
Ground.The common end of a termination first switch pipe M1 and second switch pipe M2 of inductance L1, the inductance L1 other ends are the height of output terminal
Potential end.The hot end of a termination output terminal of capacitance C, other end ground connection.The height electricity of a termination output of first resistor R1
Position end, one end of another termination second resistance R2 of first resistor R1, the other end ground connection of second resistance R2.Output voltage sampling end
FB points are arranged on the common end of first resistor R1 and second resistance R2.
As shown in Fig. 2, the abnormal detection circuit includes filter circuit, bleeder circuit, comparator comp1.Buck electricity
First switch pipe M1 and the voltage of second switch pipe M2 common ends (being denoted as SW) are as first voltage V in road1, access the filter
The input terminal of wave circuit, the output voltage of the filter circuit is as second voltage V2, the input terminal of the bleeder circuit is accessed,
The output voltage of the bleeder circuit presses V as third3, the positive input terminal of access comparator comp1, the comparator
The negative input end connection output voltage sampling end FB points of comp1, output voltage sampled signal is VFB, the comparator comp1 is defeated
Go out exception and judge signal VJ.If the exception judges signal VJFor high level, then characterize and be abnormal, can further carry out different
Often protection, takes some measures and such as shuts down or restart.
For the Switching Power Supply, during normal operating conditions, have：
Since first resistor R1 and second resistance R2 can change, user can be according to the electricity of first resistor R1 and second
Resistance R2 carrys out the output voltage of regulating switch power supply.The rated voltage V of FB points can be generally directly given in chip specificationFB.This
In the case of kind, K ∈ (Kmin, Kmax).The dividing ratios for enabling bleeder circuit are than KmaxThe constant K1 of bigger, i.e. K1 ＞ Kmax.It will filter
The output voltage V2 of wave circuit is approximately seen as the output voltage V of Switching Power Supplyout.By bleeder circuit, V is obtained3=Vout/K1
Value.When circuit is normal, V3=Vout/ K1 ＜ Vout/ K=VFB；When being abnormal at FB, i.e. R2=0 R1=+ ∝,
VFB=0, so when must have V3=Vout/Kmax＞ ＞ VFB。
It is V that the positive input terminal of comparator comp1, which receives signal,3=Vout/ K1, negative input end receive output voltage sampling letter
Number VFB, under normal operating conditions, V3=Vout/ K1 ＜ VFB, then comparator comp1 outputs low level, i.e. characterization work normally shape
State.And when FB exceptions, VFB=0, it can cause V3=Vout/K1 ＞ VFB, i.e. the positive input terminal voltage V of comparator comp13It is more than
Negative input end voltage VFB, comparator comp1 output high level, i.e. characterization is abnormal, and described abnormal generally there are two kinds of feelings
Condition, the short circuit of FB points or R1 open circuits.
After abnormal detection circuit detects exception, abnormal protection can be further carried out, is taken some measures such as shutdown
Or restart.
Embodiments described above does not form the restriction to the technical solution protection domain.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 solution
Within enclosing.
Claims (7)
1. a kind of abnormal detection circuit, which is characterized in that including：
Filter circuit receives the first voltage of characterization output voltage, the second voltage of characterization output voltage is exported after filtered；
Comparator, first input end receive the signal for characterizing the second voltage, and the second input terminal receives characterization output electricity
The voltage sampling signal of pressure, the comparator output abnormality judge signal；
When the exception judges that characterization is abnormal, then abnormal protection is carried out.
2. abnormal detection circuit according to claim 1, characteristic value are：When the signal for characterizing the second voltage is small
When the voltage sampling signal of the characterization output voltage, the exception judges characterization normal operating conditions, when characterization institute
It is described abnormal to judge characterization when stating the signal of second voltage and being more than the voltage sampling signal of the characterization output voltage
It is abnormal.
3. abnormal detection circuit according to claim 1, it is characterised in that：The abnormal detection circuit further includes partial pressure
Circuit, the input terminal of the bleeder circuit and the output terminal of filter circuit connect, the output terminal of bleeder circuit and the comparator
First input end connection, the signal of the characterization second voltage of the bleeder circuit output after partial pressure, as third electricity
Pressure, signal of the tertiary voltage as the characterization second voltage.
4. according to the abnormal detection circuit described in claim 1-3 any one, it is characterised in that：The exception refers to switch
The exception of electric power output voltage sampling end.
5. abnormal detection circuit according to claim 3, it is characterised in that：In normal operation, second electricity
Pressure and the ratio of the tertiary voltage are more than the output voltage of switching circuit and the ratio of the voltage sampling signal.
6. according to the abnormal detection circuit described in claim 1-3 any one, it is characterised in that：The characterization output voltage
First voltage refers to, master power switch pipe and the voltage of continued flow tube common end in Switching Power Supply.
7. a kind of Switching Power Supply, which is characterized in that including：Master power switch pipe, continued flow tube, inductance and claim 1-6 are arbitrary
Abnormal detection circuit described in one, the master power switch pipe are connect with the continued flow tube, common end and the inductance
One end connects, and the other end of inductance is output terminal；Filter circuit in the abnormal detection circuit and master power switch pipe and
The common end connection of the continued flow tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720723707.4U CN207586404U (en) | 2017-06-21 | 2017-06-21 | Abnormal detection circuit and Switching Power Supply |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720723707.4U CN207586404U (en) | 2017-06-21 | 2017-06-21 | Abnormal detection circuit and Switching Power Supply |
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| CN207586404U true CN207586404U (en) | 2018-07-06 |
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| CN201720723707.4U Active CN207586404U (en) | 2017-06-21 | 2017-06-21 | Abnormal detection circuit and Switching Power Supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107144798A (en) * | 2017-06-21 | 2017-09-08 | 杰华特微电子（张家港）有限公司 | Abnormal detection circuit and method and Switching Power Supply |
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2017
- 2017-06-21 CN CN201720723707.4U patent/CN207586404U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107144798A (en) * | 2017-06-21 | 2017-09-08 | 杰华特微电子（张家港）有限公司 | Abnormal detection circuit and method and Switching Power Supply |
| CN107144798B (en) * | 2017-06-21 | 2024-03-19 | 杰华特微电子（张家港）有限公司 | Abnormality detection circuit and method and switching power supply |
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