CN101447732A - Reverse-current protector used for synchronous switched voltage converter - Google Patents
Reverse-current protector used for synchronous switched voltage converter Download PDFInfo
- Publication number
- CN101447732A CN101447732A CNA200710193494XA CN200710193494A CN101447732A CN 101447732 A CN101447732 A CN 101447732A CN A200710193494X A CNA200710193494X A CN A200710193494XA CN 200710193494 A CN200710193494 A CN 200710193494A CN 101447732 A CN101447732 A CN 101447732A
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- electric current
- switch
- current
- voltage converter
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Abstract
The invention relates to a synchronous switched voltage converter, comprising an inductor, a first switch, a second switch, a current comparing unit and a time calculating unit. The current comparing unit is used for judging whether inductive current is zero or not. The time calculating unit is used for calculating the conduction duration of the second switch to ensure that the reverse current of the inductive current can be avoided under a light load mode, and then the power efficiency can be improved.
Description
Technical field
The present invention relates to a kind of synchronous switched voltage converter (SynchronousSwitching Voltage Converter), relate in particular to a kind of synchronous switched voltage converter of electric current that be used to prevent by the past input adverse current of output.
Background technology
Fig. 1 illustrates the circuit diagram of known synchronous switched voltage converter 10.Synchronous switched voltage converter 10 has control switching circuit 12, inductance L 1, output capacitance C
O1, switch S P1, and switch S N1.Input voltage V
In1Be coupled to input IN1 and output voltage V
O1Be coupled to output 01.Synchronous switched voltage converter 10 belongs to booster type, also is about to lower input voltage V
In1Convert higher output voltage V to
O1 Inductance L 1 is coupled between input IN1 and the switching node N1.Switch S P1 is coupled to 01 of switching node N1 and output, and switch S N1 then is coupled between switching node N1 and ground potential.In addition, output capacitance C
O1Be coupled to output 01, so that to output voltage V
O1Carry out filtering.In example shown in Figure 1, switch S P1 is implemented switch S N1 by the PMOS transistor and is then implemented by nmos pass transistor.Control switching circuit 12 applies the conducting (ON) and not conducting (OFF) of drive signal DN1 with determine switch SN1, and applies the conducting and not conducting of drive signal DP1 with determine switch SP1.
Particularly, control switching circuit 12 is based on output voltage V
O1Feedback and determine the duty factor of drive signal DN1 and DP1, with output voltage V
O1Be adjusted to desired value.Work as output voltage V
O1When being lower than desired value, the duty factor of drive signal DN1 and DP1 will become greatly, to improve output voltage V
O1Work as output voltage V
O1When being higher than desired value, the duty factor of drive signal DN1 and DP1 will diminish, to reduce output voltage V
O1
Fig. 2 (a) illustrates the electric current I of inductance L 1
L1Waveform sequential chart when heavy duty (Heavy Loading), Fig. 2 (b) then illustrates the electric current I of inductance L 1
L1Waveform sequential chart when underloading (Light Loading).Shown in Fig. 2 (a), when output 01 is in heavy duty, the electric current I of inductance L 1
L1The phenomenon of adverse current can not take place.Yet, shown in Fig. 2 (b), when output 01 is in underloading, the electric current I of inductance L 1
L1In time T
ATo T
BBetween can reverse direction and by output 01 toward input IN1 adverse current, thereby reduce power efficiency.
Summary of the invention
The object of the present invention is to provide a kind of reverse-current protector, be applied to synchronous switched voltage converter, when underloading, can prevent inductive current by the past input adverse current of output, and then bring to power efficient.
According to purpose of the present invention, provide a kind of synchronous switched voltage converter to convert input voltage to output voltage, it has: commutation circuit, current detecting unit, electric current comparing unit and time calculating unit.Commutation circuit has first switch, second switch and inductance.This first switch, this second switch, with this inductance coupled in common to switching node, and this inductance flows through first electric current.Current detecting unit is in order to provide second electric current, and this second electric current is proportional to this first electric current.The electric current comparing unit is by comparing A*I
2(x+y) and I
2Whether (x+A*y) equal zero at time x to differentiate this first electric current, wherein A, y represents the conduction duration of this first switch, I if being constant and satisfying inequality 0＜A＜1
2(x+y) represent the current value of this second electric current at time x+y, and I
2(x+A*y) represent the current value of this second electric current at time x+A*y.Time calculating unit utilizes the conduction duration T of the 3rd electric current and S this second switch during the cycle
PS, in order to calculate (S+1) conduction duration T of this second switch during the cycle
PS+1, wherein the 3rd electric current is proportional to this first electric current and S for greater than 1 positive integer.This current detecting unit, this electric current comparing unit, and this time calculating unit in order to avoid this first electric current generation adverse current phenomenon.
Description of drawings
Fig. 1 illustrates the circuit diagram of known synchronous switched voltage converter;
The waveform sequential chart of Fig. 2 (a) known inductive current when heavy duty is shown;
The waveform sequential chart of Fig. 2 (b) known inductive current when underloading is shown;
Fig. 3 illustrates the circuit diagram according to synchronous switched voltage converter of the present invention;
Fig. 4 (a) illustrates the waveform sequential chart according to the method for operation of synchronous switched voltage converter of the present invention when heavily loaded pattern;
Fig. 4 (b) illustrates the waveform sequential chart according to the method for operation of synchronous switched voltage converter of the present invention when becoming the underloading pattern by heavily loaded pattern.
Specific embodiment
Explanation hereinafter and accompanying drawing will make aforementioned and other purposes of the present invention, feature, more obvious with advantage.Here describe in detail according to the preferred embodiments of the present invention with reference to the accompanying drawings.
Fig. 3 illustrates the circuit diagram according to synchronous switched voltage converter 30 of the present invention.Synchronous switched voltage converter 30 has control switching circuit 32, inductance L, output capacitance C
o, switch S P, and switch S N.Input voltage V
InBe coupled to input IN and output voltage V
oBe coupled to output 0.Synchronous switched voltage converter 30 belongs to booster type, also is about to lower input voltage V
InConvert higher output voltage V to
oInductance L is coupled between input IN and the switching node N, and inductance L flows through electric current I
1Switch S P is coupled between switching node N and the output 0, and switch S N then is coupled between switching node N and the ground potential.In addition, output capacitance C
oBe coupled to output 0, and output 0 is coupled to control switching circuit 32.In example shown in Figure 3, switch S P is implemented switch S N by the PMOS transistor and is then implemented by nmos pass transistor.Control switching circuit 32 applies the conducting and not conducting of drive signal DN with determine switch SN, and applies the conducting and not conducting of drive signal DP with determine switch SP.
When Fig. 4 (a) illustrates output 0 and is in heavy duty, drive signal DN, drive signal DP and electric current I
1The waveform sequential chart.When drive signal DN and DP are high level, switch S N conducting and not conducting of switch S P, this moment inductance L electric current I
1Can increase gradually.When drive signal DN and DP are low level, not conducting of switch S N and switch S P conducting, this moment inductance L electric current I
1Can reduce gradually.Electric current I under this heavily loaded pattern operation
1The phenomenon of adverse current can not take place.
When Fig. 4 (b) then illustrates output 0 and becomes underloading by heavy duty, drive signal DN, drive signal DP and electric current I
1The waveform sequential chart.Please be simultaneously with reference to Fig. 3, Fig. 4 (a) and Fig. 4 (b) so that describe mode of operation in detail according to control switching circuit 32 of the present invention.As shown in Figure 3, control switching circuit 32 comprises current detecting unit 34, electric current comparing unit 36 and time calculating unit 38, in order to avoid the electric current I of inductance L
1The phenomenon of adverse current takes place.Current detecting unit 34 is according to electric current I
1And the generation electric current I
2And I
3, I wherein
2=I
3And electric current I
2Be proportional to electric current I
1, in order to electric current I to be provided
2To electric current comparing unit 36 and electric current I is provided
3To time calculating unit 38.
Shown in Fig. 4 (a), switch S N begins conducting at time x, at this moment electric current I
1Be minimum value I
MinAfter through switch S N conduction duration y, electric current I
1At time z is maximum I
MaxAnd z=x+y.Electric current I for fear of inductance L
1Produce backward current, at first must detect electric current I
1When be reduced to zero.Electric current comparing unit 36 is by comparing A*I
2(x+y) and I
2(x+A*y) to differentiate electric current I
1Whether equal zero at time x, wherein A is constant and satisfies inequality 0＜A＜1.I
2(x+y) expression electric current I
2At the current value of time x+y, and I
2(x+A*y) expression electric current I
2Current value at time x+A*y.Because electric current I
2Be proportional to the electric current I of inductance L
1So electric current comparing unit 36 utilizes electric current I
2Replace electric current I
1With usefulness as a comparison, wherein I
2=B*I
1, B is constant and satisfies inequality 0＜B＜1.
For easy to implement and be convenient to following explanation, the present invention selects A=0.5.I
2(x+0.5*y) expression electric current I
2At the current value of time w, I
1(x+0.5*y) expression electric current I
1At the current value of time w, wherein I
1(w)=0.5* (I
Min+ I
Max) and w=x+0.5*y.So A*I
2(x+y)=0.5*I
2(z)=0.5*B*I
Max, and I
2(x+A*y)=I
2(x+0.5*y)=I
2(w)=0.5*B* (I
Min+ I
Max).Work as I
MinGreater than zero, expression I
2(x+A*y) greater than A*I
2(x+y), the comparison signal CP of electric current comparing unit 36 output low levels.Work as I
MinReduce to zero, expression I
2(x+A*y) equal A*I
2(x+y), the comparison signal CP of 36 output of electric current comparing unit high level.
Shown in Fig. 4 (b), drive signal DN and DP have period T, T
1Be the time started in S cycle, i.e. T
1=(S-1) * T, this moment I
1Electric current be zero, wherein S is the positive integer greater than 1.As process switch S N conduction duration T
NSAfter, in time T
2The comparison signal CP that electric current comparing unit 36 can be exported high level operates in underloading pattern, wherein T to time calculating unit 38 to represent present synchronous switched voltage converter 30
2=T
1+ T
NSAs previously mentioned, because I
3=I
2=B*I
1So time calculating unit 38 utilizes electric current I
3Calculate (S+1) switch S P conduction duration T the during cycle
PS+1, (S+2) switch S P conduction duration T the during cycle
PS+2, (S+3) switch S P conduction duration T the during cycle
PS+3Deng, to avoid electric current I
1The adverse current phenomenon takes place.
Shown in Fig. 4 (b), when time computing unit 38 receives the comparison signal CP of high level, at first can storage time T
2The time electric current I
3, that is I
3(T
2).As process switch S P conduction duration T
PSAfter, in time T
3The time I
1Electric current be zero, T wherein
3=T
2+ T
PSTime T
3The concluding time that is the S cycle also is the time started in (S+1) cycle.Time calculating unit can store the switch S P conduction duration T of S during the cycle 38 this moments
PSAs process switch S N conduction duration T
NS+1After, time calculating unit 38 then can storage time T
4The time electric current I
3, that is I
3(T
4), T wherein
4=T
3+ T
NS+1For fear of electric current I
1In time T
5The adverse current phenomenon takes place afterwards, and time calculating unit 38 will be according to the I that stores before
3(T
2), I
3(T
4) and T
PSIn order to determine the switch S P conduction duration T in (S+1) cycle
PS+1, electric current I wherein
1In time T
5In time, equal zero and T
5=T
4+ T
PS+1Follow the switch S P conduction duration T that control switching circuit 32 meetings are calculated according to time calculating unit 38
PS+1Make not conducting of switch S P in order to the controlling and driving signals DP.Therefore, electric current I
1In time T
5To T
6Between be maintained zero, time T wherein
6Be the concluding time in (S+1) cycle, this moment, synchronous switched voltage converter 30 operated in discontinuous current pattern (Discontinuous Current Mode).
Because the electric current I of inductance L
1Descend with fixing slope, so T
2, T
3, and I
1Formed triangle can be similar to T
4, T
5, and I
1Formed triangle is shown in Fig. 4 (b).Utilize two characteristics that triangle is similar, can get T
PS+1=T
PS* I
1(T
4)/I
1(T
2)=T
PS* I
3(T
4)/I
3(T
2), I wherein
1(T
2) the expression electric current I
1In time T
2Current value and I
1(T
4) the expression electric current I
1In time T
4Current value.Similarly, (S+2) switch S P conduction duration T the during cycle
PS+2, (S+3) switch S P conduction duration T the during cycle
PS+3Deng, but applications similar leg-of-mutton characteristics and pushing away all just repeats no more at this.
Therefore, control switching circuit 32 is understood the switch S P conduction duration T that pushes away according to time calculating unit 38
PS+1, T
PS+2, T
PS+3Deng in order to produce drive signal DP, prevent the electric current I of inductance L thus
1The adverse current phenomenon takes place, and then bring to power efficient, and make synchronous switched voltage converter 30 under the underloading pattern, operate in the discontinuous current pattern.The present invention also may be implemented in step-down shape electric pressure converter except the shape electric pressure converter that can be applicable to boost.
Though the present invention is illustrated as illustration by preferred embodiment, will be appreciated that: the invention is not restricted to this disclosed embodiment.On the contrary, the invention is intended to contain tangible various modifications and similar configuration for persons skilled in the art.Therefore, the scope of claim should be according to the widest annotation, and this type of is revised and similar configuration to contain all.
Claims (7)
1, a kind of switch type electric voltage converter in order to convert input voltage to output voltage, comprising:
Commutation circuit has first switch, second switch and inductance, wherein this first switch, this second switch, with this inductance coupled in common to switching node, and this inductance flows through first electric current;
Current detecting unit, in order to second electric current to be provided, described second electric current is proportional to described first electric current; And
The electric current comparing unit is by comparing A*I
2(x+y) and I
2Whether (x+A*y) equal zero at time x to differentiate described first electric current, wherein A, y represents the conduction duration of described first switch, I if being constant and satisfying inequality 0＜A＜1
2(x+y) represent the current value of described second electric current at time x+y, and I
2(x+A*y) described second electric current of expression is at the current value of time x+A*y.
2, switch type electric voltage converter as claimed in claim 1 also comprises:
Time calculating unit, utilize the conduction duration of the 3rd electric current and S described second switch during the cycle, in order to calculating (S+1) conduction duration of described second switch during the cycle, wherein said the 3rd electric current is proportional to described first electric current and S for greater than 1 positive integer.
3, switch type electric voltage converter as claimed in claim 1, wherein A equals 0.5.
4, switch type electric voltage converter as claimed in claim 1, wherein said switch type electric voltage converter belongs to booster type.
5, switch type electric voltage converter as claimed in claim 2, wherein said electric current comparing unit outputs to described time calculating unit with comparison signal, operates in the underloading pattern in order to represent described synchronous switched voltage converter.
6, switch type electric voltage converter as claimed in claim 5, wherein said current detecting unit, described electric current comparing unit, with described time calculating unit in order to avoid the described first electric current generation adverse current phenomenon.
7, switch type electric voltage converter as claimed in claim 2, wherein said switch type electric voltage converter operate in the discontinuous current pattern when the underloading pattern.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710193494XA CN101447732A (en) | 2007-11-27 | 2007-11-27 | Reverse-current protector used for synchronous switched voltage converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710193494XA CN101447732A (en) | 2007-11-27 | 2007-11-27 | Reverse-current protector used for synchronous switched voltage converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101447732A true CN101447732A (en) | 2009-06-03 |
Family
ID=40743198
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA200710193494XA Pending CN101447732A (en) | 2007-11-27 | 2007-11-27 | Reverse-current protector used for synchronous switched voltage converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101447732A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102158080A (en) * | 2010-03-02 | 2011-08-17 | 成都芯源系统有限公司 | Voltage converter and control method thereof |
| CN102751868A (en) * | 2011-07-07 | 2012-10-24 | 矽创电子股份有限公司 | Voltage converter |
| CN103516218A (en) * | 2012-06-28 | 2014-01-15 | 善元科技股份有限公司 | Power supply device |
| CN104768256A (en) * | 2014-01-02 | 2015-07-08 | 深圳市海洋王照明工程有限公司 | Synchronous shutdown LED boost driving circuit |
| CN104160603B (en) * | 2012-03-07 | 2016-08-03 | 意法-爱立信有限公司 | Control circuit, control method, dc-dc and electronic equipment |
| CN106841746A (en) * | 2016-12-29 | 2017-06-13 | 深圳市拓革科技有限公司 | A kind of converter current detects circuit and its control method |
-
2007
- 2007-11-27 CN CNA200710193494XA patent/CN101447732A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102158080A (en) * | 2010-03-02 | 2011-08-17 | 成都芯源系统有限公司 | Voltage converter and control method thereof |
| CN102751868A (en) * | 2011-07-07 | 2012-10-24 | 矽创电子股份有限公司 | Voltage converter |
| CN104160603B (en) * | 2012-03-07 | 2016-08-03 | 意法-爱立信有限公司 | Control circuit, control method, dc-dc and electronic equipment |
| CN103516218A (en) * | 2012-06-28 | 2014-01-15 | 善元科技股份有限公司 | Power supply device |
| CN103516218B (en) * | 2012-06-28 | 2016-01-20 | 善元科技股份有限公司 | Power supply device |
| CN104768256A (en) * | 2014-01-02 | 2015-07-08 | 深圳市海洋王照明工程有限公司 | Synchronous shutdown LED boost driving circuit |
| CN104768256B (en) * | 2014-01-02 | 2019-04-12 | 深圳市海洋王照明工程有限公司 | Synchronous shutdown LED booster driving circuit |
| CN106841746A (en) * | 2016-12-29 | 2017-06-13 | 深圳市拓革科技有限公司 | A kind of converter current detects circuit and its control method |
| CN106841746B (en) * | 2016-12-29 | 2019-02-26 | 深圳市拓革科技有限公司 | A kind of converter current detection circuit and its control method |
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Open date: 20090603 |