CN207459711U - Output protection circuit - Google Patents
Output protection circuit Download PDFInfo
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- CN207459711U CN207459711U CN201720547642.2U CN201720547642U CN207459711U CN 207459711 U CN207459711 U CN 207459711U CN 201720547642 U CN201720547642 U CN 201720547642U CN 207459711 U CN207459711 U CN 207459711U
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Abstract
The utility model discloses a kind of output protection circuits; the utility model is provided with multiple and different threshold voltages; to judge whether voltage sampling signal reaches respective threshold; so as to judge whether de-preservation pattern; whenever voltage sampling signal reaches a threshold voltage; reclocking then is carried out to switch periodicity, so as to prevent that output short circuit protection is by false triggering in bulky capacitor and heavy load startup.The utility model can effectively be compatible with the application scenario of heavy load and bulky capacitor, and erroneous judgement will not occur, so as to improve the reliability of product.
Description
Technical field
The utility model is related to a kind of power electronics field, more particularly to a kind of output protection circuit.
Background technology
In on-off circuit, generally by sampling and outputting voltage, and it is distinguished into error originated from input with corresponding reference voltage
Amplifier carries out Error processing, the output characterization of the error amplifier difference of the two.There is a situation where short circuit
Under, the output of error amplifier can deviate normal value, increase to clamper threshold value, and the judgement of short circuit is carried out with this.It is short in generation
Lu Hou, the output of error amplifier are clamped to maximum, and the on-off circuit enters short-circuit protection.
In the prior art, under the operating mode of short-circuit protection, according to output voltage to determine whether recovering from short circuit
Normally, for example, hiccup pattern (Hiccup), Latch off modes, etc..Judge whether to recover the normal time from short circuit
General shorter (for example, 1000 to 2000 switch periods), suitable for the smaller occasion of output capacitance.But for larger negative
It carries in the case of being bulky capacitor with output capacitance, it is difficult to which output voltage is charged to judgment threshold in the short period again, be easy to cause
Erroneous judgement, in fact it could happen that even if after unshorting recovers normal, it is also difficult to be judged in time.
The prior art is generally by extending the time judged, for example, 3,40,000 switch periods are extended to, it is above-mentioned to solve
Technical problem, but this process is it is possible that triggering overheat protector, power consumption are also relatively large.
Utility model content
The purpose of this utility model is to provide a kind of output protection circuit, for solving existing in the prior art judge by accident
Disconnected, the technical issues of reliability is not high.
To achieve the above object, the utility model provides a kind of output protection circuit, including：
Error amplifier receives both the voltage sampling signal and reference voltage of characterization output voltage, output characterization respectively
The error signal of difference；
Comparison circuit receives the voltage sampling signal of characterization output voltage and multiple threshold voltages of different sizes, described
Voltage sampling signal often reach a threshold voltage, then export a trigger signal；
In non-shorting on-off circuit start-up course, when the rate of climb of voltage sampling signal is slower than the ginseng
When examining the rate of climb of voltage, then the on-off circuit can also enter protected mode, continue in switch periods number or on off state
Before time reaches corresponding preset value, if voltage sampling signal rising reaches the lowest threshold voltage in the threshold voltage
When, then restart to count or to the reclocking of on off state duration switch periodicity；In switch periods number or switch
Before state duration reaches corresponding preset value, if the rising of output voltage sampled signal reaches next threshold voltage, weigh again
It is new to start to count switch periodicity or to the timing of on off state duration, until voltage sampling signal reaches the threshold value electricity
Highest threshold voltage in pressure, the output voltage of the error amplifier level off to the reference voltage, then exit protected mode,
On-off circuit start completion simultaneously works normally.
Optionally, when short circuit occurs, the output voltage sampled signal can reduce, the output of the error amplifier
Voltage increases, and when reaching predetermined threshold value, on-off circuit enters protected mode；In protected mode, there are on off state and not
Dormancy state on off state, counts switch periodicity or carries out timing to the on off state duration, when switch week
When issue or on off state duration reach corresponding preset value, then the master power switch pipe shutdown switch of on-off circuit, goes forward side by side
Enter dormant state；In dormant state, the time of dormant state is calculated, when the time of dormant state reaching its preset value, then
Access switch state；
The comparison circuit judges the value of the output voltage, and switch periodicity is counted again according to the trigger signal
Or to the reclocking of on off state duration；When the voltage sampling signal levels off to the reference voltage, then guarantor is released
Shield, the on-off circuit recover normal work.
Optionally, the output protection circuit further includes time control circuit, and the time control circuit is equipped with timing
Control terminal resets end and control output end, and the timing control terminal receives timing signal, and the replacement end, which receives, resets letter
Number, the control output end output protection mode control signal.
Optionally, the timing signal by be used for switch periodicity counted or to the on off state duration into
The signal of row timing and the clock signal of characterization dormancy time generate.
Optionally, the signal for being used to counting switch periodicity or carrying out the on off state duration timing
It inputs two input terminals of the first OR gate respectively with clock signal, the timing signal is exported by first OR gate.
Optionally, the output terminal of the error amplifier is connected with clamper detection circuit, and the clamper detection circuit is used
Whether reach clamper threshold value in the output signal for detecting the amplifier, if detect that it reaches clamper threshold value, by error
Signal is clamped to clamped voltage value, the size of the clamper threshold value and clamped voltage value can it is equal can not also be equal.
Optionally, the output terminal of the comparison circuit is connected with pulse generating circuit, and the pulse generating circuit receives
The trigger signal, and corresponding pulse signal is generated according to trigger signal, the timing is accessed by the pulse signal
The replacement end of control circuit.
Optionally, clamped voltage value characterization high level, inputs wherein the one of the second OR gate after being negated to high level
A input terminal, another input terminal of second OR gate receive the pulse signal, are exported by second OR gate described heavy
Confidence number.
Optionally, the comparison circuit includes the multiple and one-to-one comparator of the threshold voltage, each to compare
The first input end of device receives the voltage sampling signal of the characterization output voltage, the second input terminal difference of each comparator
Corresponding threshold voltage is received, the output terminal of multiple comparators is connected with the pulse generating circuit.
Optionally, the maximum in the multiple threshold voltage levels off to the reference voltage.
Compared with prior art, the technical solution of the utility model has the following advantages：The utility model is provided with multiple
Different threshold voltages, to judge whether voltage sampling signal reaches respective threshold, so as to judge whether to release short-circuit protection,
Whenever voltage sampling signal reaches a threshold voltage, then reclocking is carried out to switch periodicity, so as to prevent bulky capacitor and
Output short circuit protection is by false triggering when starting when heavy load is applied, adaptively using corresponding switch periods number.The utility model
The application scenario of heavy load and bulky capacitor can be effectively compatible with, erroneous judgement will not occur, so as to improve the reliability of product.
Description of the drawings
Fig. 1 is the structure diagram of the utility model output protection circuit；
Fig. 2 is the oscillogram of timing signal；
Fig. 3 is the generation schematic diagram of reset signal.
Specific embodiment
The preferred embodiment of the utility model is described in detail below in conjunction with attached drawing, but the utility model is not merely
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 referring to the drawings 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.
As shown in Figure 1, a kind of circuit structure of the utility model output protection circuit is illustrated, available for various switch electricity
Road.The output protection circuit includes error amplifier EA, comparison circuit and time control circuit.The error amplifier EA
The error letter of both characterization voltage sampling signal VFB of output voltage and reference voltage VREF, output characterization differences is received respectively
Number Vc, the output voltage are the output voltage of on-off circuit.The comparison circuit includes multiple comparators, in the present embodiment
The situation using tri- comparators of comparator comp1, comp2 and comp3 is listed, the first input end of each comparator connects
The voltage sampling signal VFB of characterization output voltage is received, the second input terminal of multiple comparators receives corresponding threshold voltage, example
Such as, comparator comp1 receives threshold voltage V1, and comparator comp2 receives threshold voltage V2, and comparator comp3 receives threshold value electricity
V3, the voltage sampling signal VFB is pressed often to reach a threshold voltage, then exports a trigger signal, that is, works as voltage sample
When signal VFB reaches threshold voltage V1, then comparator comp1 exports trigger signal, and output voltage continues to rise, then voltage sample
Signal VFB reaches threshold voltage V2, then comparator comp2 exports trigger signal, and so on.The time control circuit is equipped with
Timing control terminal TIME-CLK, end Reset and control output end OUT is reset, the timing control terminal receives timing signal, described
Replacement end receive reset signal, the control output end output protection mode control signal Short-ctrl.
When short circuit occurs, the output voltage sampled signal can reduce, and the output voltage of the error amplifier increases
Greatly, (can be judged when reaching predetermined threshold value by way of directly detecting voltage), on-off circuit enters protected mode；It is protecting
Under shield pattern, there are on off state and dormant state, on off state, switch periodicity is counted or timing, when opening
When pass periodicity reaches its preset value, then the master power switch pipe shutdown switch of on-off circuit, and enter dormant state；In dormancy
During state, the time of dormant state is calculated, when the time of dormant state reaching its preset value, then access switch state；
By comparing the value of output voltage described in circuit judges, switch periodicity is counted again according to the trigger signal
Or timing；When the voltage sampling signal levels off to the reference voltage, then de-preservation, the on-off circuit recover normal
Work.The reference signal it is also assumed that be to start threshold value, i.e., when the voltage sampling signal level off to it is described with reference to electricity
Then judge that system starts during pressure.
The timing signal is stopped by the duty cycle signals Ton and characterization of characterization on-off circuit master power switch pipe duty cycle
The clock signal Clock of dormancy time is generated, and the dormancy time time refers to the time there is no switch motion.Described accounts for
Sky inputs two input terminals of the first OR gate OR1 than signal Ton and clock signal Clock respectively, defeated by the first OR gate OR1
Go out the timing signal to timing control terminal TIME-CLK.
The output terminal output Vc signals of the error amplifier EA, are connected with clamper detection circuit, clamper detection
For circuit for detecting whether the error signal Vc reaches clamper threshold value, clamper threshold value here can be used as the default threshold
Value, if detect that it reaches clamper threshold value, clamped voltage value, the clamper threshold value and clamper are clamped to by error signal
The size of voltage value can it is equal can not also be equal.The output signal of the clamper detection circuit is negated, obtains signalIt is characterized as low level.The clamped voltage value characterization high level, inputs the second OR gate after being negated to high level
One of input terminal of OR2, another input terminal of the second OR gate OR2 receives the pulse signal Vplus, by described
Second OR gate OR2 exports the reset signal.Substantially, the clamper detection circuit in addition to clamping action, use by also output
The signal of short-circuit conditions whether occurs in characterizationWhen on-off circuit works normally, signalFor high electricity
Flat, so keep Reset states, time control circuit does not also enter protected mode without timing at this time, when circuit occurs,
The clamper detection circuit detects the variation of error signal Vc, so as to carry out clamper, the signal exportedCharacterization
For low level, then end Reset received signals are reset as low level, time control circuit is controlled into protected mode, and
Start timing under the action of timing signal.
The comparison circuit include it is multiple with the one-to-one comparator of the threshold voltage, the first of each comparator
Input terminal receives the voltage sample of the characterization output voltage (in the present embodiment using in-phase input end as first input end)
Signal, the second input terminal (in the present embodiment using inverting input as the second input terminal) of each comparator receive accordingly respectively
Threshold voltage, the output terminal of multiple comparators is connected with the pulse generating circuit, the pulse generating circuit
The trigger signal is received, and corresponding pulse signal is generated according to trigger signal, the pulse generating circuit is not held
It is continuous to generate pulse, but corresponding real estate gives birth to pulse signal when saltus step occurs for comparator.Three are only listed in the present embodiment
Comparator, but the quantity of comparator can change.Maximum and the reference signal in the multiple threshold voltage are (i.e.
Judge that output voltage recovers normal value) it is equal.By taking attached drawing 1 as an example, in protected mode, when voltage sampling signal VFB reaches
During threshold voltage V3, then it can determine whether that on-off circuit recovers normal work from short circuit, protected mode can be exited at this time.Threshold value
The size of voltage V3 can be used as the last one judgement, it is also possible to determine whether recovering from protected mode normal.It in addition, can
With the difference according to application scenario, the quantity of comparator and the quantity of threshold voltage and size are selected, meanwhile, it can carry out adaptive
It should ground selection and design.
Refering to what is shown in Fig. 2, illustrate the oscillogram of timing signal, including duty cycle signals Ton and clock signal Clock,
It is only that the principle of timing is illustrated in figure, but there are many kinds of deformation, Er Qieji for the waveform that can be realized in principle
Number or the mode of timing can also have many variations, for example, the timing signal is only with a signal, while realize switch
Timing during period and dormancy.
Refering to what is shown in Fig. 3, the schematic diagram of reset signal generation is illustrated, including signalAnd pulse signal
The waveform of Vpluse.Before short circuit occurs, signalHigh level is remained, after being judged as short circuit, then saltus step is low electricity
It is flat.Short circuit occur before, will not pulsing signal, after being judged as short circuit, whenever voltage sampling signal VFB reaches a threshold value
During voltage, then a pulse signal Vpluse is sent, switch periodicity is counted time control circuit again or timing.
It should be noted that counting and timing for two opposite concepts or belong to, can be realized by way of counting
Timing can also be counted by way of timing, but the metering regular hour substantially.The utility model has not only acted as short
The effect of road protection, while in bulky capacitor and heavy load in application, short circuit recovers and when circuit start of non-shorting situation can be with
It is effectively prevented the erroneous judgement of short circuit.
Although embodiment is separately illustrated and is illustrated above, it is related to the common technology in part, in ordinary skill
Personnel apparently, can be replaced and integrate between the embodiments, be related to one of embodiment and the content recorded is not known, then
It can refer to another embodiment on the books.
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 (8)
1. a kind of output protection circuit, it is characterised in that：Including：
Error amplifier receives both the voltage sampling signal and reference voltage of characterization output voltage, output characterization difference respectively
Error signal；
Comparison circuit receives the voltage sampling signal of characterization output voltage and multiple threshold voltages of different sizes, the electricity
Pressure sampled signal often reaches a threshold voltage, then exports a trigger signal；
The output protection circuit further includes time control circuit, and the time control circuit is equipped with timing control terminal, resets
End and control output end, the timing control terminal receive timing signal, and the replacement end receives reset signal, and the control is defeated
Outlet output protection mode control signal.
2. output protection circuit according to claim 1, it is characterised in that：The timing signal is by being used for switch week
The clock signal of signal and characterization dormancy time that issue was counted or carried out to the on off state duration timing generates.
3. output protection circuit according to claim 2, it is characterised in that：It is described to be used to count switch periodicity
Or input two input terminals of the first OR gate respectively to the signal and clock signal of the progress timing of on off state duration, by institute
It states the first OR gate and exports the timing signal.
4. output protection circuit according to claim 1, it is characterised in that：The output terminal of the error amplifier is connected with
Whether clamper detection circuit, the output signal that the clamper detection circuit is used to detect the error amplifier reach clamper threshold
Value, if detect that it reaches clamper threshold value, clamped voltage value, the clamper threshold value and clamper are clamped to by error signal
Voltage value it is equal in magnitude or unequal.
5. output protection circuit according to claim 4, it is characterised in that：The output terminal of the comparison circuit is connected with arteries and veins
Circuit occurs for punching, and the pulse generating circuit receives the trigger signal, and generates corresponding pulse according to trigger signal
Signal accesses the replacement end of the time control circuit by the pulse signal.
6. output protection circuit according to claim 5, it is characterised in that：The clamped voltage value characterization high level,
One of input terminal of the second OR gate is inputted after being negated to high level, described in another input terminal of second OR gate receives
Pulse signal exports the reset signal by second OR gate.
7. output protection circuit according to claim 5, it is characterised in that：The comparison circuit include it is multiple with it is described
The one-to-one comparator of threshold voltage, the first input end of each comparator receive the voltage for characterizing output voltage and adopt
Sample signal, the second input terminal of each comparator receive corresponding threshold voltage, the output terminal of multiple comparators respectively
It is connected with the pulse generating circuit.
8. output protection circuit according to claim 1, it is characterised in that：Maximum in the multiple threshold voltage becomes
It is bordering on the reference voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720547642.2U CN207459711U (en) | 2017-05-17 | 2017-05-17 | Output protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720547642.2U CN207459711U (en) | 2017-05-17 | 2017-05-17 | Output protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN207459711U true CN207459711U (en) | 2018-06-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201720547642.2U Active CN207459711U (en) | 2017-05-17 | 2017-05-17 | Output protection circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN207459711U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110048374A (en) * | 2019-05-05 | 2019-07-23 | 广州金升阳科技有限公司 | The control method and converter of a kind of output short circuit protection circuit, converter |
-
2017
- 2017-05-17 CN CN201720547642.2U patent/CN207459711U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110048374A (en) * | 2019-05-05 | 2019-07-23 | 广州金升阳科技有限公司 | The control method and converter of a kind of output short circuit protection circuit, converter |
| CN110048374B (en) * | 2019-05-05 | 2022-04-15 | 广州金升阳科技有限公司 | Output short-circuit protection circuit, control method of converter and converter |
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Legal Events
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address |
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 Patentee after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Patentee before: JOULWATT TECHNOLOGY (HANGZHOU) Co.,Ltd. |
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| CP03 | Change of name, title or address |