CN104113196B - Assistant starting method and auxiliary starting circuit and apply its buck converter - Google Patents
Assistant starting method and auxiliary starting circuit and apply its buck converter Download PDFInfo
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- CN104113196B CN104113196B CN201410317914.0A CN201410317914A CN104113196B CN 104113196 B CN104113196 B CN 104113196B CN 201410317914 A CN201410317914 A CN 201410317914A CN 104113196 B CN104113196 B CN 104113196B
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Abstract
The invention discloses a kind of assistant starting method and auxiliary starting circuit, it is applied to buck converter, described buck converter includes ON time generation circuit, ON time generation circuit is by relatively producing ON time to reference voltage and ramp signal, and described reference voltage is provided by energy-storage travelling wave tube；Described auxiliary starting circuit includes output end voltage sample circuit, before buck converter starts, it is pre-charged to energy-storage travelling wave tube by output end voltage sampling circuit samples output end voltage, when the voltage of energy-storage travelling wave tube reaches the value corresponding with output end voltage, then disconnect auxiliary starting circuit, stop energy-storage travelling wave tube being charged, now start buck converter.The invention also discloses a kind of buck converter including auxiliary starting circuit.Energy-storage travelling wave tube in ON time generation circuit is pre-charged before buck converter starts by the present invention, it is thus achieved that the initial turn-on time corresponding with output end voltage, will not produce negative current, reduce product power consumption.
Description
Technical field
The present invention relates to electric and electronic technical field, be specifically related to a kind of assistant starting method and assistant starting
Circuit and apply its buck converter.
Background technology
Supply convertor is widely used in electronic product, it is achieved voltage-regulation and power conversion.At certain
Under a little application scenarios, it is understood that there may be the situation of " before circuit start, output end voltage is not zero ".Example
As, in the electric power system of notebook computer, input voltage by adapter through supply convertor is again
System is powered or charges the battery, due to the existence of battery, before supply convertor starts, its outfan
Output voltage is not zero.As a example by synchronous step-down converter, in the control model using fixing ON time
Under, owing to the benchmark in ON time control circuit during circuit start is zero, so ON time is very
Short (time between when closed less than minimum ON time, then use the minimum ON time of setting), in output
In the case of voltage is not zero, the output voltage that supply convertor produces in above-mentioned ON time is difficult to reach
To initial output voltage, output end voltage can be caused to pour in down a chimney and produce the phenomenon of negative current, extend startup
Time, add the power consumption of product.
Summary of the invention
In view of this, it is an object of the invention to provide a kind of assistant starting method and auxiliary starting circuit and
Apply its buck converter, during to solve to start present in prior art output end voltage be not zero and
The problem producing negative current.
The technical solution of the present invention is to provide the auxiliary starting circuit of a kind of following structure, is applied to
Buck converter, described buck converter includes ON time generation circuit, ON time generation circuit
By reference voltage and ramp signal are relatively produced ON time, the voltage of energy-storage travelling wave tube is as institute
The reference voltage stated；Described auxiliary starting circuit includes output end voltage sample circuit, at decompression transformation
Before device starts, output end voltage sampling circuit samples output end voltage it is pre-charged to energy-storage travelling wave tube, works as storage
When the voltage of energy element reaches the value corresponding with initial output end voltage, then disconnect auxiliary starting circuit,
Stop energy-storage travelling wave tube being charged, now start buck converter.
Preferably, after buck converter starts, at the beginning of producing by turn-on time generation circuit according to reference voltage
Beginning ON time, makes buck converter produce the output voltage more than or equal to initial output end voltage, with
Holding inductive current is forward current.
Preferably, described auxiliary starting circuit also includes voltage follower, described voltage follower
Input is connected with output end voltage sample circuit, and its outfan is connected with energy-storage travelling wave tube.
Preferably, auxiliary starting circuit also includes the switch controlling its break-make, and described switch is arranged on electricity
Between pressure follower and energy-storage travelling wave tube.
Preferably, described output end voltage sample circuit is by the bleeder circuit of two resistant series.
Another technical solution of the present invention is to provide a kind of assistant starting method of following steps, should
For buck converter, described buck converter includes ON time generation circuit, and ON time occurs
Circuit is by relatively producing ON time to reference voltage and ramp signal, and the voltage of energy-storage travelling wave tube is made
For described reference voltage；
The step of described assistant starting method is as follows: before buck converter starts, to energy-storage travelling wave tube preliminary filling
Electricity, when the voltage of energy-storage travelling wave tube reaches the value corresponding with output end voltage, then stops energy-storage travelling wave tube
Charging, now starts buck converter.
Preferably, after buck converter starts, produce initial turn-on time according to reference voltage, make blood pressure lowering
Changer produces the output voltage more than or equal to initial output end voltage, to keep inductive current as forward
Electric current.
The another technical solution of the present invention is to provide the buck converter of a kind of following structure, including
The auxiliary starting circuit of said structure.
Use the structures and methods of the present invention, compared with prior art, have the advantage that the present invention exists
Buck converter start before the energy-storage travelling wave tube in ON time generation circuit is pre-charged, with produce and
The initial turn-on time that output end voltage is corresponding, then disconnects charging, decompression transformation after completing assistant starting
Device is owing to obtaining the initial turn-on time corresponding with output end voltage, so negative current will not be produced,
Shorten the startup time, reduce product power consumption.
Accompanying drawing explanation
Fig. 1 is the structural representation of auxiliary starting circuit of the present invention and the buck converter applying it；
Fig. 2 is the startup working waveform figure of prior art.
Fig. 3 is the startup working waveform figure of the present invention.
Detailed description of the invention
To assistant starting method and the auxiliary starting circuit of the present invention and it is applied below in conjunction with schematic diagram
Buck converter is for a more detailed description, which show the preferred embodiments of the present invention, it should be appreciated that this
On the basis of skilled person can be described herein, within the scope of the claims to physical circuit of the present invention
Convert and replace, and still realize the advantageous effects of the present invention.Description below is not intended as this
Bright restriction.
Referring to the drawings the present invention the most more particularly described below in the following passage.It should be noted that,
Accompanying drawing all uses the form more simplified and all uses non-ratio accurately, only in order to convenient, the most auxiliary
Help the purpose of the explanation embodiment of the present invention.
The core of the present invention is, it is provided that a kind of auxiliary starting circuit, is applied to buck converter, described
Buck converter include ON time generation circuit, ON time generation circuit by reference voltage and
Ramp signal relatively produce ON time, described reference voltage is provided by energy-storage travelling wave tube；Described
Auxiliary starting circuit includes output end voltage sample circuit, before buck converter starts, by outfan electricity
Pressure sampling circuit samples output end voltage is pre-charged to energy-storage travelling wave tube, when the voltage of energy-storage travelling wave tube reaches with just
During the corresponding value of beginning output end voltage, then disconnect auxiliary starting circuit, stop energy-storage travelling wave tube being charged,
Now start buck converter.
Further, the present invention also provides for a kind of assistant starting method, is applied to buck converter, described
Buck converter include ON time generation circuit, ON time generation circuit by reference voltage and
Ramp signal relatively produce ON time, described reference voltage is provided by energy-storage travelling wave tube；
The step of described assistant starting method is as follows: before buck converter starts, to energy-storage travelling wave tube preliminary filling
Electricity, when the voltage of energy-storage travelling wave tube reaches the value corresponding with output end voltage, then stops energy-storage travelling wave tube
Charging, now starts buck converter.
With reference to shown in Fig. 1, illustrate auxiliary starting circuit and apply its buck converter.Described fall
Buckling parallel operation includes master power switch pipe Q1 and synchro switch pipe Q2, PWM controller control main
Power switch pipe Q1 and the on off state of synchro switch pipe Q2, PWM controller output duty cycle signal
Duty cycle, duty cycle signals duty cycle control the on off state of Q1.PWM controller is according to defeated
Go out voltage feedback circuit to open master power switch pipe Q1, turn off master power switch pipe according to ON time
Q1.Described ON time is produced by turn-on time generation circuit, and turn-on time generation circuit includes oblique wave
Circuit and energy-storage travelling wave tube, slope circuit produces ramp signal, enters the voltage of ramp signal and energy-storage travelling wave tube
Row compares, thus produces ON time, when this ON time is less than the minimum ON time set, then
Using minimum ON time as final ON time, the ON time that i.e. produces at ON time circuit and
Minimum ON time takes maximum as final ON time.Slope circuit includes current source I, opens
Close Q5 and electric capacity C2.
Described energy-storage travelling wave tube uses electric capacity C1, before buck converter starts, if not entering electric capacity C1
In the case of line precharge, the voltage on electric capacity C1 is zero.Due to the particularity of use occasion, in fall
Before buckling parallel operation does not the most start, the voltage of its outfan is not zero, now when buck converter starts,
The ON time that turn-on time generation circuit produces is the shortest, is generally less than minimum ON time, it is difficult to produce
In the output voltage that output end voltage matches, then can produce the phenomenon of negative current in circuit.Therefore Fig. 1
Middle employing auxiliary starting circuit solves this problem, i.e. before buck converter starts, to electric capacity C1
Being pre-charged so that it is reach the value corresponding with output end voltage, this value is according to output end voltage
And draw, on the premise of meeting certain ON time, buck converter first on startup can be made
After switch periods, its output voltage reaches the magnitude of voltage of initial outfan, thus prevents negative current phenomenon
Occur.
Can counter be pushed away by initial output end voltage, if buck converter produces equal with initial output voltage
Output voltage time, it can be deduced that the reference voltage Vref 1 on electric capacity C1, make current source I=Vin/R,
Vref1=Vin/R D R1, D are the dutyfactor value of duty cycle signals duty cycle, R and R1 is
The amount of knowing, according to above-mentioned equation, chooses the resistance of resistance R2, R3 in output end voltage sample circuit, and
Draw initial turn-on time Ton.I.e. auxiliary starting circuit will by the voltage pre-charge of electric capacity C1 extremely
Vin/R D R1, then output end voltage Vout R3/ (R2+R3)=Vin/R D R1, Vout are output
Terminal voltage, thus draw R3/ (R2+R3)=R1/R.According to the relation of ramp signal Yu Vref1,
Vref1=Vin/R/C1 Ton(TonON time produced by turn-on time generation circuit),
Ton=D R1 C1.
Auxiliary starting circuit includes output end voltage sample circuit, and output end voltage sample circuit uses by R2
The bleeder circuit formed with R3, before buck converter starts, can be by bleeder circuit directly to electric capacity C1
It is charged reaching corresponding reference voltage Vref 1.If output end voltage is bigger before starting,
Then corresponding reference voltage Vref 1 is the biggest, in order to improve the current carrying capacity of auxiliary starting circuit,
Adding voltage follower A between bleeder circuit and electric capacity C1, voltage follower A input accesses
Bleeder circuit, outfan charges to electric capacity C1, and the voltage of its input and outfan is equal.Voltage with
There is multiple implementation with device, include but not limited to layer follower and integrated transporting discharging voltage follow
Device.
Switch Q3 is for controlling the state of charging, before buck converter starts, and switch Q3 Guan Bi, thus
Electric capacity C1 is charged, when charging to corresponding reference voltage Vref 1, then disconnects Q3 and stop charging,
Now start buck converter, can produce equal with initial output end voltage after first ON time
Output voltage, be effectively prevented the phenomenon that negative current occurs.
After buck converter starts, auxiliary starting circuit quits work, by generating circuit from reference voltage root
Corresponding reference voltage is produced according to output voltage (being characterized by dutyfactor value D), thus to electric capacity
The voltage of C1 is adjusted.Described generating circuit from reference voltage includes current source I, switch Q4 and electricity
Resistance R1, the control end of described switch Q4 is controlled by duty cycle signals duty cycle.
With reference to shown in Fig. 2, Fig. 2 illustrates start-up course and the work wave of prior art buck converter,
Power represents the time starting power supply, and Q1 represents the ON time of Q1, ILRepresent the big of inductive current
Little, Vout represents the size of output voltage.After starting power supply, start buck converter, at the beginning of existing
Beginning output end voltage, and the ON time matched with output end voltage cannot be produced (during initial turn-on
Between generally minimum ON time), thus inductive current ILThere will be the negative current phenomenon of a period of time,
Output end voltage also decreases, when reference voltage reaches be worth corresponding with output end voltage, and inductance electricity
Stream ILRise to therewith on the occasion of.
With reference to shown in Fig. 3, Fig. 3 illustrates start-up course and the work that have employed under the circuit structure of the present invention
Making waveform, in the case of output end voltage Vout is not zero, after starting power supply, Q3 turns on, by auxiliary
Help start-up circuit that electric capacity C1 is charged, charge to the reference voltage level corresponding with output end voltage
Time, open buck converter, produce the ON time corresponding with output end voltage, now decompression transformation
Device can export the output voltage equal with initial output end voltage, therefore inductive current ILWill not produce negative
The phenomenon of electric current, output end voltage Vout also can rise therewith.
Embodiments described above, is not intended that the restriction to this technical scheme protection domain.Any
Amendment, equivalent and the improvement etc. made within the spirit of above-mentioned embodiment and principle, all should comprise
Within the protection domain of this technical scheme.
Claims (6)
1. an auxiliary starting circuit, is applied to buck converter, when described buck converter includes conducting
Between there is circuit, ON time generation circuit is by relatively producing conducting to reference voltage and ramp signal
Time, the voltage of energy-storage travelling wave tube is as described reference voltage；
It is characterized in that: described auxiliary starting circuit includes output end voltage sample circuit, at decompression transformation
Before device starts, output end voltage sampling circuit samples output end voltage it is pre-charged to energy-storage travelling wave tube, works as energy storage
When the voltage of element reaches the value corresponding with initial output end voltage, then disconnect auxiliary starting circuit, stop
Energy-storage travelling wave tube is charged, now starts buck converter；
After buck converter starts, produced initial turn-on time according to reference voltage by turn-on time generation circuit,
Buck converter is made to produce the output voltage more than or equal to initial output end voltage, to keep inductive current to be
Forward current.
Auxiliary starting circuit the most according to claim 1, it is characterised in that: described assistant starting electricity
Road also includes that voltage follower, the input of described voltage follower are connected with output end voltage sample circuit,
Its outfan is connected with energy-storage travelling wave tube.
Auxiliary starting circuit the most according to claim 2, it is characterised in that: auxiliary starting circuit also wraps
Including the switch controlling its break-make, described switch is arranged between voltage follower and energy-storage travelling wave tube.
Auxiliary starting circuit the most according to claim 1, it is characterised in that: described output end voltage
Sample circuit is by the bleeder circuit of two resistant series.
5. an assistant starting method, it is characterised in that: it is applied to buck converter, described decompression transformation
Device includes ON time generation circuit, and ON time generation circuit is by the ratio to reference voltage and ramp signal
Relatively producing ON time, described reference voltage is provided by energy-storage travelling wave tube；
It is characterized in that: the step of described assistant starting method is as follows: before buck converter starts, give storage
Can be pre-charged by element, when the voltage of energy-storage travelling wave tube reaches the value corresponding with output end voltage, then it is right to stop
Energy-storage travelling wave tube charges, and now starts buck converter；
After buck converter starts, produce initial turn-on time according to reference voltage, make buck converter produce
More than or equal to the output voltage of initial output end voltage, to keep inductive current as forward current.
6. a buck converter, it is characterised in that: include the auxiliary described in claim 1-4 any one
Start-up circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410317914.0A CN104113196B (en) | 2014-07-04 | 2014-07-04 | Assistant starting method and auxiliary starting circuit and apply its buck converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410317914.0A CN104113196B (en) | 2014-07-04 | 2014-07-04 | Assistant starting method and auxiliary starting circuit and apply its buck converter |
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| Publication Number | Publication Date |
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| CN104113196A CN104113196A (en) | 2014-10-22 |
| CN104113196B true CN104113196B (en) | 2016-10-05 |
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| CN201410317914.0A Active CN104113196B (en) | 2014-07-04 | 2014-07-04 | Assistant starting method and auxiliary starting circuit and apply its buck converter |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107086767B (en) * | 2017-06-20 | 2023-12-15 | 杰华特微电子（张家港）有限公司 | Drive control circuit and method |
| CN110112906B (en) * | 2019-06-24 | 2020-10-27 | 珠海格力电器股份有限公司 | Parameter determination method and device, storage medium and switching power supply |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1977443A (en) * | 2004-07-12 | 2007-06-06 | 株式会社村田制作所 | DC-DC converter |
| CN102498653A (en) * | 2009-07-22 | 2012-06-13 | 沃福森微电子股份有限公司 | Improvements in dc-dc converters |
| CN103166442A (en) * | 2013-03-27 | 2013-06-19 | 华为技术有限公司 | Device for preventing current of buck circuit from flowing reversely, converter and power supply |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8482270B2 (en) * | 2006-05-02 | 2013-07-09 | Advanced Analogic Technologies Incorporated | Reverse current comparator for switching regulators |
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2014
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1977443A (en) * | 2004-07-12 | 2007-06-06 | 株式会社村田制作所 | DC-DC converter |
| CN102498653A (en) * | 2009-07-22 | 2012-06-13 | 沃福森微电子股份有限公司 | Improvements in dc-dc converters |
| CN103166442A (en) * | 2013-03-27 | 2013-06-19 | 华为技术有限公司 | Device for preventing current of buck circuit from flowing reversely, converter and power supply |
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| CN104113196A (en) | 2014-10-22 |
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Address after: 310051 No. 6 Lianhui Street, Xixing Street, Binjiang District, Hangzhou City, Zhejiang Province Patentee after: Silergy Semiconductor Technology (Hangzhou ) Co., Ltd. Address before: 310012 Wensanlu Road, Hangzhou Province, No. 90 East Software Park, science and technology building A1501 Patentee before: Silergy Semiconductor Technology (Hangzhou ) Co., Ltd. |