CN102769386A - Switching converter and control circuit and control method thereof - Google Patents
Switching converter and control circuit and control method thereof Download PDFInfo
- Publication number
- CN102769386A CN102769386A CN2012102639909A CN201210263990A CN102769386A CN 102769386 A CN102769386 A CN 102769386A CN 2012102639909 A CN2012102639909 A CN 2012102639909A CN 201210263990 A CN201210263990 A CN 201210263990A CN 102769386 A CN102769386 A CN 102769386A
- Authority
- CN
- China
- Prior art keywords
- signal
- circuit
- modulation signal
- control
- value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Abstract
The invention discloses a switching converter and a control circuit and a control method thereof. The switching converter comprises a switching circuit comprising a main switching tube. The control circuit comprises a first comparison circuit, a modulation signal generating circuit, a second comparison circuit and a logic circuit, wherein the first comparison circuit receives a current detection signal which refers to current flowing through the main switching tube, compares the current detection signal with a peak current signal and generates a turn-on time control signal; the modulation signal generating circuit generates a modulation signal, wherein the slope of the modulation signal is changed along with the value of the modulation signal; the second comparison circuit receives the modulation signal and a feedback signal related to output of a switching circuit and generates a turn-off time control signal based on the modulation signal and the feedback signal; and the logic circuit is coupled to the first comparison circuit and the second comparison circuit so as to receive the turn-on time control signal and the turn-off time control signal and generates a control signal for controlling on/off of the main switching tube based on the turn-on time control signal and the turn-off time control signal.
Description
Technical field
The present invention relates generally to a kind of electronic circuit, relates in particular to switch converters and control circuit thereof and control method.
Background technology
The power loss of switch converters mainly comes from the conduction loss or the switching loss of switching tube.Under the situation of heavy duty, output off current HIGH, so conduction loss is in the highest flight.Under underloading or ideal case, output current is low, and the switching loss of switching tube in the highest flight.If still with primary frequency work, significant switching loss can reduce conversion efficiency to switch converters when underloading.For this reason, can reduce the switching loss of switch converters under the light condition through the mode of frequency reducing.
A kind of solution commonly used is to adopt the turn-off time control mode that is easy to realize the underloading frequency reducing.Fig. 1 is a kind of circuit diagram of switch converters 100 of existing employing turn-off time control.Switch converters 100 is operated in the discontinuous current pattern, receives input voltage V
IN, for load 150 provides output voltage V
OOr output current I
OSwitch converters 100 comprises switching circuit, feedback circuit 140 and control circuit.Wherein switching circuit adopts the inverse-excitation converting topology, comprises input capacitor C
IN, transformer T, diode D, output capacitor C
OUTAnd switching tube M.Control circuit comprises capacitor C
M, current source I
M0, discharge switch pipe S, first comparison circuit 110, second comparison circuit 120 and trigger 130.Current source I
M0An end be coupled to supply power voltage V
CC, the other end is coupled to capacitor C
MWith the end of discharge switch pipe S, capacitor C
MOther end ground connection with discharge switch pipe S.The output signal U of feedback circuit 140 receiving key circuit
O(output voltage V
O, output current I
OPerhaps both combinations), produce the feedback signal FB of reflected load state.Second comparison circuit 120 is with feedback signal FB and capacitor C
MThe voltage V at two ends
M0Compare.First comparison circuit 110 flows through representative the current detection signal CS and the peak-current signal V of switching tube M electric current
PeakCompare.
As shown in Figure 1, during switching tube M conducting, current detection signal CS increases gradually.When current detection signal CS reaches peak-current signal V
PeakThe time, first comparison circuit, 110 reset flip-flops 130, switching tube M turn-offs.As capacitor C
MThe voltage V at two ends
M0During greater than feedback signal FB, second comparison circuit, 120 set flip-flops 130, switching tube M conducting once more.Second comparison circuit, 120 output pulse signal Pulse are to the control end of discharge switch pipe S simultaneously, and conducting discharge switch pipe S one preset duration Tp makes capacitor C
MThe voltage V at two ends
M0Reduce to zero.After preset duration Tp finished, discharge switch pipe S broke off, current source I
M0Again be capacitor C
MCharging, capacitor C
MThe voltage V at two ends
M0Linear growth.When load reduced, feedback signal FB increased, current source I
M0To capacitor C
MCharging interval elongated, the turn-off time of switching tube M is elongated, the operating frequency of switch converters 100 reduces.
In the application of reality, the inventor finds current source I
M0Choose and have certain problem.For example, we hope current source I on the one hand
M0The magnitude of current as far as possible little, to reduce the operating frequency of switch converters, the switching loss when effectively suppressing underloading when the underloading to greatest extent.Yet on the other hand, we hope current source I again
M0The magnitude of current want enough big, when guaranteeing that switch converters is operated in high frequency, feedback signal FB can reach the requirement (enough greatly, usually greater than 50mV) of signal resolution, to avoid receiving the interference of system noise.
Summary of the invention
To one or more problems of the prior art, the purpose of this invention is to provide switch converters and control circuit thereof and control method, it can guarantee the requirement of signal resolution, can effectively suppress the switching loss of switch converters again.
In one aspect of the invention; A kind of control circuit that is used for switch converters is proposed; This switch converters comprises the switching circuit with main switch, and this control circuit comprises: first comparison circuit receives the current detection signal that the main switch electric current is flow through in representative; Current detection signal is compared with peak-current signal, produce the ON time control signal; Modulated signal producing circuit produces modulation signal, and the slope of this modulation signal becomes along with the value of modulation signal; Second comparison circuit receives modulation signal and exports relevant feedback signal with switching circuit, based on modulation signal and feedback signal, produces the turn-off time control signal; And logical circuit, be coupled to first and second comparison circuits to receive ON time control signal and turn-off time control signal, based on ON time control signal and turn-off time control signal, produce the control signal of said main switch conducting of control and shutoff.
In another aspect of the present invention, a kind of switch converters is proposed, comprise foregoing control circuit.
Of the present invention aspect another; A kind of control method that is used for switch converters is also proposed; This switch converters comprises the switching circuit with main switch; This control method comprises: the current detection signal that representative is flow through the main switch electric current is compared with peak-current signal, produces the ON time control signal; Produce modulation signal, the slope of this modulation signal becomes along with the value of modulation signal; Modulation signal is compared with the relevant feedback signal of switching circuit output with one, produce the turn-off time control signal; Based on ON time control signal and turn-off time control signal, produce the control signal of said main switch conducting of control and shutoff.
Description of drawings
For a better understanding of the present invention, will describe the present invention based on following accompanying drawing:
Fig. 1 is a kind of circuit diagram of switch converters 100 of existing employing turn-off time control;
Fig. 2 is the block diagram of switch converters 200 according to an embodiment of the invention;
Fig. 3 is the circuit diagram of switch converters 300 according to an embodiment of the invention;
Fig. 4 is the oscillogram of switch converters among Fig. 3 according to an embodiment of the invention;
Fig. 5 is modulation signal V according to an embodiment of the invention
MWith controlled current source I
MBetween concern sketch map;
Fig. 6 is the circuit diagram of modulated signal producing circuit 302 among Fig. 3 according to an embodiment of the invention;
Fig. 7 is the oscillogram of modulated signal producing circuit 302 shown in Figure 6 according to an embodiment of the invention;
Fig. 8 is the flow chart of switch converters control method 800 according to an embodiment of the invention.
Embodiment
To describe specific embodiment of the present invention in detail below, should be noted that the embodiments described herein only is used to illustrate, be not limited to the present invention.In the following description, in order to provide, a large amount of specific detail have been set forth to thorough of the present invention.Yet it is obvious that for those of ordinary skills: needn't adopt these specific detail to carry out the present invention.In other instances,, do not specifically describe known circuit, material or method for fear of obscuring the present invention.
In whole specification, " embodiment ", " embodiment ", " example " or mentioning of " example " are meaned: the special characteristic, structure or the characteristic that combine this embodiment or example to describe are comprised among at least one embodiment of the present invention.Therefore, phrase " in one embodiment ", " in an embodiment ", " example " or " example " that occurs in each place of whole specification differs to establish a capital and refers to same embodiment or example.In addition, can with any suitable combination with or sub-portfolio with specific feature, structure or property combination in one or more embodiment or example.In addition, it should be understood by one skilled in the art that at this diagrammatic sketch that provides all be for illustrative purposes, and diagrammatic sketch is not necessarily to draw in proportion.Should be appreciated that when claiming that " element " " is connected to " or " coupling " during to another element it can be directly to connect or be couple to another element or can have intermediary element.On the contrary, when claiming that element " is directly connected to " or during " directly being couple to " another element, not having intermediary element.Identical Reference numeral indication components identical.Term used herein " and/or " comprise any and all combinations of one or more relevant projects of listing.
Fig. 2 is the block diagram of switch converters 200 according to an embodiment of the invention, comprises control circuit, switching circuit 205 and feedback circuit 206.Switching circuit 205 comprises main switch, and the conducting through main switch converts input signal IN into output signal OUT with turn-offing.Input signal IN and output signal OUT can be voltage, electric current or power signal.Switching circuit 205 can adopt any DC topological structure, for example synchronous or asynchronously boosts, buck converter, and normal shock, anti exciting converter or the like.Feedback circuit 206 is coupled to switching circuit 205, and the output signal OUT of sampling switch circuit produces the relevant feedback signal FB with output signal OUT.In one embodiment, feedback circuit 206 can comprise resitstance voltage divider and error amplifier etc.
Control circuit comprises first comparison circuit 201, modulated signal producing circuit 202, second comparison circuit 203 and logical circuit 204.First comparison circuit 201 is coupled to switching circuit 205; Receive representative and flow through the current detection signal CS of main switch electric current; And current detection signal CS compared with peak-current signal, produce ON time control signal Ton, with the ON time of main switch in the control switch circuit 205.
Modulated signal producing circuit 202 is used to provide modulation signal V
M, this modulation signal V
MSlope along with modulation signal V
MValue and become.In one embodiment, modulation signal V
MValue big more, modulation signal V
MThe rate of rise more little, vice versa.Second comparison circuit 203 is coupled to modulated signal producing circuit 202 and feedback circuit 206, with modulation signal V
MFB compares with feedback signal, produces turn-off time control signal Toff, with the turn-off time of control switch circuit 205 main switches.Logical circuit 204 is coupled to first comparison circuit 201 and second comparison circuit 202, based on ON time control signal Ton and turn-off time control signal Toff, produces control signal Gate, with the conducting and the shutoff of control main switch.
In one embodiment, modulated signal producing circuit 202 comprises capacitor C
M, discharge switch pipe K
M, controlled current source I
MWith the pulse-generating circuit 212 that is used to produce discharge pulse signal Pulse.Capacitor CM has first end and second end, and wherein first end is used to provide modulation signal V
M, the second end ground connection.Discharge switch pipe K
MHave first end, second end and control end, wherein first end is coupled to capacitor C
MFirst end, the second end ground connection, control end is coupled to pulse-generating circuit 212 to accept discharge pulse signal Pulse.Controlled current source I
MHave control end, feeder ear and output, wherein control end is coupled to capacitor C
MFirst end to receive modulation signal V
M, feeder ear is coupled to supply power voltage Vcc, and output is coupled to capacitor C
MFirst end, be capacitor C
MCharging current is provided.
Controlled current source I
MControl end be coupled to modulation signal V
M, controlled current source I
MThe magnitude of current along with modulation signal V
MValue and change so capacitor C
MThe rate of rise of voltage, i.e. modulation signal V
MSlope also with modulation signal V
MValue and change.In one embodiment, as modulation signal V
MValue when increasing, controlled current source I
MThe magnitude of current reduce modulation signal V
MThe rate of rise reduce; As modulation signal V
MValue when reducing, controlled current source I
MThe magnitude of current increase modulation signal V
MThe rate of rise increase.
Fig. 3 is the circuit diagram of switch converters 300 according to an embodiment of the invention.Switch converters 300 comprises control circuit, switching circuit and feedback circuit.Switching circuit adopts the inverse-excitation converting topology, receives input voltage V
IN, for load provides output voltage V
OUTSwitching circuit comprises transformer T, main switch M, secondary diode D and output capacitor C
OUT, its connection is as shown in the figure.Transformer T comprises former limit winding Np, secondary winding Ns and auxiliary winding Na.In the embodiment shown in fig. 3, main switch M is MOSFET.In other embodiments, main switch M can adopt the suitable transistor of other types.
As shown in Figure 3, feedback circuit comprises resistor voltage divider circuit 307, sampling hold circuit 308 and error amplifier EA.Resistor voltage divider circuit 307 comprises resistor R 1 and R2, is coupled to the two ends of the auxiliary winding Na of transformer T, and the voltage of assisting winding Na two ends is carried out dividing potential drop, obtains a voltage sampling signal Vs
0 Sampling hold circuit 308 is coupled to the output of resistor voltage divider circuit 308 to receive voltage sampling signal Vs
0, and produce one at its output and represent the switching circuit output voltage V
OUTVoltage detection signal Vs.Error amplifier EA has in-phase input end that receives voltage detection signal Vs and the inverting input that receives reference voltage Vref, and error amplifier EA produces and the relevant feedback signal FB of switching circuit output at its output.In other embodiments, feedback circuit is coupled to the output of switching circuit, the output voltage V of sampling switch circuit
OUT, and produce one with the switching circuit output voltage V
OUTRelevant feedback signal FB.Among embodiment, feedback circuit comprises photoelectric coupled device and three-terminal voltage-stabilizing device therein.
Control circuit comprises first comparison circuit 301, modulated signal producing circuit 302, the second comparison circuits 303 and logical circuits 304.First comparison circuit 301 comprises comparator C OM1.Comparator C OM1 has in-phase input end, inverting input and output, in-phase input end received current detection signal CS wherein, and inverting input is coupled to peak-current signal V
Peak, output provides ON time control signal Ton, with the ON time of main switch M in the control switch circuit.Any one method in many known sampling switch tube current methods, for example current transformer or sampling resistor all can be used for detecting the electric current that flows through main switch M.
Modulated signal producing circuit 302 comprises capacitor C
M, discharge switch pipe K
M, controlled current source I
MWith pulse-generating circuit 312.Pulse-generating circuit 312 is used to produce discharge pulse signal Pulse, with control discharge switch pipe K
MConducting and shutoff.In each work period of discharge pulse signal Pulse, when discharge pulse signal Pulse is low level, discharge switch pipe K
MBe in off state, controlled current source I
MTo capacitor C
MCharging, capacitor C
MThe voltage at two ends (is modulation signal V
M) non-linear growth of starting from scratch; When discharge pulse signal Pulse is high level, discharge switch pipe K
MConducting, capacitor C
MThe voltage at two ends reduces to zero.
In one embodiment, control circuit is integrated circuit or discrete electronic devices and components.In another embodiment, main switch M in control circuit and the switching circuit 306 and the error amplifier EA in the feedback circuit are integrated in the same control IC.
Fig. 4 is the oscillogram of switch converters 300 among Fig. 3 according to an embodiment of the invention.As shown in Figure 4, in each work period, when main switch M conducting, the electric current I p that flows through main switch M begins to increase, and current detection signal CS also increases.When current detection signal CS reaches peak-current signal V
PeakThe time, first comparison circuit 301 produces the ON time control signal Ton of high level, and the low level control signal Gate of triggering for generating is to turn-off main switch M.As modulation signal V
MValue greater than feedback signal FB, second comparison circuit 303 produces the turn-off time control signal Toff of high level, the control signal Gate of triggering for generating high level is with main switch M conducting again.Switching circuit gets into next switch periods then, and operation as stated.
As previously mentioned, modulation signal V
MSlope along with modulation signal V
MValue and become.As shown in Figure 4, when load was heavier, feedback signal FB was little, modulation signal V
MValue also less, modulation signal V
MThe rate of rise corresponding bigger, modulation signal V
MBut rapidly increase to feedback signal FB within a short period of time, satisfy the requirement of switch converters signal resolution.Along with load lightens, feedback signal FB increases, modulation signal V
MValue increase modulation signal V thereupon
MThe rate of rise diminish, slowed down modulation signal V
MReach the speed of feedback signal FB, so controlled current source I
MBe capacitor C
MThe time of charging becomes longer, and switching frequency is greatly reduced, thereby has satisfied the requirement of switch converters to efficient.
Fig. 5 is modulation signal V according to an embodiment of the invention
MWith controlled current source I
MConcern sketch map.According to modulation signal V
MValue adjust controlled current source I
MThe magnitude of current, and according to controlled current source I
MThe magnitude of current control modulation signal V
MSlope.Controlled current source I
MThe magnitude of current big more, modulation signal V
MSlope more little, vice versa.Controlled current source I
MThe magnitude of current and modulation signal V
MRelation be: a). as modulation signal V
MSmaller or equal to first threshold V
M1The time, controlled current source I
MThe magnitude of current be fixed on maximum I
MAXB). as modulation signal V
MBe in first threshold V
M1With the second threshold value V
M2Between the time, controlled current source I
MThe magnitude of current with modulating function f (V
M) change; C). as modulation signal V
MGreater than the second threshold value V
M2, controlled current source I
MThe magnitude of current be fixed on minimum value I
MINAs shown in Figure 4, controlled current source I
MThe magnitude of current and modulation signal V
MFunctional relation be:
Modulating function f (V wherein
M) should satisfy following three conditions:
a).f(V
M1)＝I
MAX；
b).f(V
M2)＝I
MIN；
C) .f (V
M) along with V
MIncrease and reduce.
In one embodiment, modulating function f (V
M) can be:
Although in Fig. 3, provided specific modulated signal producing circuit 302, in other embodiments, can also adopt other circuit structures to produce the modulation signal V of non-linear growth
M, digital mode for example.
Fig. 6 is the circuit diagram of modulated signal producing circuit 302 among Fig. 3 according to an embodiment of the invention.Modulated signal producing circuit 302 comprises capacitor C
M, discharge switch pipe K
M, controlled current source I
MAnd pulse signal generating circuit 312.In one embodiment, modulated signal producing circuit 302 also comprises double limiting circuit 313 and buffering circuit 314.
As shown in Figure 6, double limiting circuit 313 has input and output respectively with buffering circuit 314, and wherein the input of buffer circuit 314 is coupled to capacitor C
MFirst end to receive modulation signal V
M, the output of buffer circuit 314 is coupled to the input of double limiting circuit 313, and the output of double limiting circuit 313 is coupled to controlled current source I
MControl end so that current controling signal to be provided.In one embodiment, as modulation signal V
MValue during less than first threshold, double limiting circuit 313 is fixed on minimum value with current controling signal; As modulation signal V
MValue during greater than second threshold value, double limiting circuit 313 is fixed on maximum with current controling signal.
Among the embodiment as shown in Figure 6, controlled current source has the first control end V
+With the second control end V
-, the first control end V
+Pass through voltage source V
1Be coupled to ground.Double limiting circuit 313 comprises resistor R0, diode D2 and D3 and direct voltage source V
2And V
3One end of resistor R0 is coupled to the output of buffer circuit 313, and the other end is coupled to controlled current source I
MThe second control end V
-, the negative electrode of diode D2 and the anode of diode D3.The anode of diode D2 is through direct voltage source V
2Be coupled to ground, the negative electrode of diode D3 is through direct voltage source V
3Be coupled to ground.
Wherein, resistor R0, diode D2 and direct voltage source V
2Form the lower limit amplitude limiter, work as V
M＜V
2, diode D2 conducting, controlled current source I
MThe second control end V
-Voltage be V
2Resistor R0, diode D3 and direct voltage source V
3Form upper limit amplitude limiter, work as V
M＞V
3, diode D3 conducting, controlled current source I
MThe second control end V
-Voltage be V
3The upper and lower limit amplitude limiter is combined, formed double limiting circuit 313 as shown in Figure 6.In addition, in the embodiment shown in fig. 6, because direct voltage source V
1Be coupled in controlled current source I
MThe first control end V
+And between the ground, controlled current source I
MThe minimum value of current controling signal is V
1-V
3, maximum is V
1-V
2
Discharge pulse produces circuit 312 and is used to produce discharge pulse signal Pulse.In one embodiment, ON time tons and the interrupting time tdcm of the ON time tonp of discharge pulse signal Pulse and main switch M, secondary diode D are relevant.When main switch M conducting or secondary diode D conducting, discharge pulse signal Pulse keeps high level, discharge switch pipe K
MConducting; As main switch M and secondary diode D all during not conducting, discharge pulse signal Pulse keeps low level, discharge switch pipe K
MTurn-off.
In the embodiment shown in fig. 6, discharge pulse generation circuit 312 comprises testing circuit 310 and or door 325.Testing circuit 310 is used to detect secondary ON time tons, to produce the pulse signal Tons of reflection secondary ON time.Testing circuit 310 comprises trigger 320, first not gate 321, second not gate 322, the first and second rising edge testing circuits 323 and 324 and comparator C OM3.Trigger 320 has set end S, reset terminal R and output Q.First not gate 321 has input and output, and its input is coupled to control signal Gate, and output is coupled to the input of the first rising edge testing circuit 323.The output of the first rising edge testing circuit 323 meets the set end S of trigger 320.Comparator C OM3 has in-phase input end, inverting input and output, and wherein in-phase input end is coupled to reference signal V
REFX(for example 100mV), inverting input are coupled to voltage sampling signal V shown in Figure 3
S0, output is coupled to the input of second not gate 322.The output of second not gate 322 is coupled to the input of the second rising edge testing circuit 324.The output of the second rising edge testing circuit 325 is coupled to the reset terminal of trigger 320.Trigger 320 promptly produces the pulse signal Tons of reflection secondary ON time at its output at the output of testing circuit 310.
Or door 325 has first input end, second input and output, and wherein first input end is coupled to the output (being the output of trigger 320) of testing circuit 310, and second input is coupled to control signal Gate, and output is coupled to discharge switch pipe K
MControl end so that discharge pulse signal Pulse to be provided.
In one embodiment, when for example switching circuit was the boosting inverter topology, discharge pulse signal Pulse was that the zero-time is relevant with inductive current rise time, inductive current fall time and inductive current.In the time period that inductive current rises or inductive current descends, discharge pulse signal Pulse keeps high level, discharge switch pipe K
MConducting; In inductive current was time period of zero, discharge pulse signal Pulse kept low level, discharge switch pipe K
MTurn-off.
Fig. 7 is the oscillogram of modulated signal producing circuit 302 shown in Figure 6 according to an embodiment of the invention.When the trailing edge arriving of control signal Gate, when promptly secondary diode D began conducting, pulse signal Tons saltus step was a high level; As voltage sampling signal V
S0Trailing edge arrive, i.e. when secondary diode D conducting finished, pulse signal Tons saltus step was a low level.At pulse signal Tons is between high period and control signal Gate is between high period, and discharge pulse signal Pulse keeps high level, otherwise discharge pulse signal Pulse is a low level.
In one embodiment; Discharge pulse produces circuit 312 can comprise other circuit structure that can produce discharge pulse signal Pulse as shown in Figure 7; For example, discharge pulse generation circuit 312 can comprise the timer Count1 of timing main switch M ON time tonp, the timer Count2 of timing secondary diode ON time tons and the timer Count3 of timing interrupting time tdcm.When timer Count1 or Count2 timing, discharge pulse produces circuit 312 output high level; When timer Count3 clocked, discharge pulse produced circuit 312 output low levels.
In another embodiment, pulse-generating circuit 312 can comprise monostable flipflop, and monostable flipflop is coupled in the output and the discharge switch pipe K of second comparison circuit 303 shown in Figure 3
MControl end between.As turn-off time control signal Toff when being high, monostable flipflop output high level pulse conducting discharge switch pipe K
MOne preset duration Tp makes capacitor C
MThe voltage at two ends reduces to zero.After preset duration Tp finishes, discharge switch pipe K
MTurn-off current source I
MAgain be capacitor C
MCharging.
Fig. 8 is the flow chart that is used for the control method 800 of switch converters according to an embodiment of the invention, and this switch converters comprises the switching circuit with main switch, and this control method 800 comprises step 801～804.
Step 801: the current detection signal that representative is flow through the main switch electric current is compared with peak-current signal, produces the ON time control signal, with the ON time of control main switch.
Step 802: produce modulation signal, the slope of this modulation signal becomes with the value of modulation signal.In one embodiment, the slope of modulation signal reduces with the increase of modulation signal value.
Step 803: modulation signal is compared with the relevant feedback signal of switching circuit output with one, produce the turn-off time control signal, with the turn-off time of control main switch.
Step 804:, produce the control signal of control main switch conducting and shutoff based on ON time control signal and turn-off time control signal.
In one embodiment, when the value of modulation signal less than first threshold, the slope of modulation signal is fixed on ceiling value; When the value of modulation signal was between the first threshold and second threshold value, the slope of modulation signal reduced with the increase of modulation signal value; When the value of modulation signal greater than second threshold value, the slope of modulation signal is fixed on minimum limit value.
Only the present invention will be described in an exemplary fashion for some above-mentioned specific embodiments, and these embodiment are not fully detailed, and be not used in the scope of the present invention that limits.It all is possible changing and revise for disclosed embodiment, other feasible selection property embodiment and can be understood by those skilled in the art the equivalent variations of element among the embodiment.Other variations of disclosed embodiment of this invention and modification do not exceed spirit of the present invention and protection range.
Claims (10)
1. control circuit that is used for switch converters, this switch converters comprises the switching circuit with main switch, this control circuit comprises:
First comparison circuit receives the current detection signal that the main switch electric current is flow through in representative, and current detection signal is compared with peak-current signal, produces the ON time control signal;
Modulated signal producing circuit produces modulation signal, and the slope of this modulation signal becomes along with the value of modulation signal;
Second comparison circuit receives modulation signal and exports relevant feedback signal with switching circuit, based on modulation signal and feedback signal, produces the turn-off time control signal; And
Logical circuit is coupled to first and second comparison circuits to receive ON time control signal and turn-off time control signal, based on ON time control signal and turn-off time control signal, produces the control signal of said main switch conducting of control and shutoff.
2. control circuit as claimed in claim 1, wherein modulated signal producing circuit comprises:
Pulse-generating circuit is used to produce discharge pulse signal;
Capacitor has first end and second end, and wherein first end is used to provide modulation signal, the second end ground connection;
The discharge switch pipe has first end, second end and control end, and wherein first end is coupled to first end of capacitor, the second end ground connection, and control end is coupled to pulse-generating circuit to receive discharge pulse signal; And
Controlled current source has control end and feeder ear and output, and wherein feeder ear is coupled to supply power voltage, and control end and output all are coupled to first end of capacitor, and wherein the electric current of controlled current source reduces with the increase of modulation signal value.
3. control circuit as claimed in claim 2; Wherein modulated signal producing circuit further comprises the double limiting circuit; This double limiting circuit has input and output, wherein input be coupled to capacitor first end to receive modulation signal, output is coupled to the control end of controlled current source so that current controling signal to be provided; Wherein in the value of modulation signal during less than first threshold, the double limiting circuit is fixed on minimum value with current controling signal; When the value of modulation signal during greater than second threshold value, the double limiting circuit is fixed on maximum with current controling signal.
4. control circuit as claimed in claim 3, wherein controlled current source has first control end and second control end, and first control end is coupled to ground through first voltage source, and the double limiting circuit comprises:
Resistor has first end and second end, and wherein first end is coupled to first end of capacitor, and second end is coupled to second control end of controlled current source;
First diode has anode and negative electrode, and wherein anode is coupled to second end of resistor;
Second DC source is coupled between the negative electrode and ground of first diode;
Second diode has anode and negative electrode, and wherein negative electrode is coupled to second end of resistor; And
The 3rd DC source is coupled between the anode and ground of second diode.
5. control circuit as claimed in claim 3, wherein modulated signal producing circuit further comprises the buffer circuit that is coupled between capacitor first end and the double limiting circuit input end.
6. control circuit as claimed in claim 1, wherein:
When the value of modulation signal during less than first threshold, the slope of modulation signal is fixed on ceiling value;
When the value of modulation signal was between the first threshold and second threshold value, the slope of modulation signal reduced with the increase of modulation signal value;
When the value of modulation signal during greater than second threshold value, the slope of modulation signal is fixed on minimum limit value.
7. a switch converters comprises like each described control circuit in the claim 1 to 6.
8. control method that is used for switch converters, this switch converters comprises the switching circuit with main switch, this control method comprises:
The current detection signal that representative is flow through the main switch electric current is compared with peak-current signal, produces the ON time control signal;
Produce modulation signal, the slope of this modulation signal becomes along with the slope of modulation signal;
Modulation signal is compared with the relevant feedback signal of switching circuit output with one, produce the turn-off time control signal;
Based on ON time control signal and turn-off time control signal, produce the control signal of said main switch conducting of control and shutoff.
9. control method as claimed in claim 8, wherein the slope of modulation signal reduces with the increase of modulation signal value.
10. control method as claimed in claim 9, wherein:
When the value of modulation signal less than first threshold, the slope of modulation signal is fixed on ceiling value;
When the value of modulation signal was between the first threshold and second threshold value, the slope of modulation signal reduced with the increase of modulation signal value;
When the value of modulation signal greater than second threshold value, the slope of modulation signal is fixed on minimum limit value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210263990.9A CN102769386B (en) | 2012-07-27 | 2012-07-27 | Switching converter and control circuit and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210263990.9A CN102769386B (en) | 2012-07-27 | 2012-07-27 | Switching converter and control circuit and control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102769386A true CN102769386A (en) | 2012-11-07 |
| CN102769386B CN102769386B (en) | 2014-08-13 |
Family
ID=47096665
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210263990.9A Active CN102769386B (en) | 2012-07-27 | 2012-07-27 | Switching converter and control circuit and control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102769386B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105244848A (en) * | 2015-10-30 | 2016-01-13 | 杰华特微电子（杭州）有限公司 | Overvoltage protection method and circuit |
| CN108923650A (en) * | 2018-06-27 | 2018-11-30 | 成都芯源系统有限公司 | A kind of multi-phase converter and its control circuit and control method |
| CN111239465A (en) * | 2020-01-16 | 2020-06-05 | 昂宝电子（上海）有限公司 | Line voltage detection circuit, system and method |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030227279A1 (en) * | 2002-06-07 | 2003-12-11 | Martin Feldtkeller | Method for driving a switch in a switch-mode converter, and a drive circuit for driving a switch |
| US20090196074A1 (en) * | 2008-01-31 | 2009-08-06 | Hang-Seok Choi | Resonant Converter |
| US20100194362A1 (en) * | 2009-02-05 | 2010-08-05 | Freescale Semiconductor, Inc. | Regulator with pulse width modulation circuit |
| CN102005911A (en) * | 2009-09-01 | 2011-04-06 | 安凯(广州)微电子技术有限公司 | Piecewise linear slope compensation method and circuit |
| CN102594097A (en) * | 2012-03-13 | 2012-07-18 | 成都芯源系统有限公司 | Switching power supply, and control circuit and control method thereof |
-
2012
- 2012-07-27 CN CN201210263990.9A patent/CN102769386B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030227279A1 (en) * | 2002-06-07 | 2003-12-11 | Martin Feldtkeller | Method for driving a switch in a switch-mode converter, and a drive circuit for driving a switch |
| US20090196074A1 (en) * | 2008-01-31 | 2009-08-06 | Hang-Seok Choi | Resonant Converter |
| US20100194362A1 (en) * | 2009-02-05 | 2010-08-05 | Freescale Semiconductor, Inc. | Regulator with pulse width modulation circuit |
| CN102005911A (en) * | 2009-09-01 | 2011-04-06 | 安凯(广州)微电子技术有限公司 | Piecewise linear slope compensation method and circuit |
| CN102594097A (en) * | 2012-03-13 | 2012-07-18 | 成都芯源系统有限公司 | Switching power supply, and control circuit and control method thereof |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105244848A (en) * | 2015-10-30 | 2016-01-13 | 杰华特微电子（杭州）有限公司 | Overvoltage protection method and circuit |
| CN105244848B (en) * | 2015-10-30 | 2019-02-15 | 杰华特微电子（杭州）有限公司 | Over-voltage protection method and circuit |
| CN108923650A (en) * | 2018-06-27 | 2018-11-30 | 成都芯源系统有限公司 | A kind of multi-phase converter and its control circuit and control method |
| CN108923650B (en) * | 2018-06-27 | 2021-05-18 | 成都芯源系统有限公司 | Multiphase converter and control circuit and control method thereof |
| CN111239465A (en) * | 2020-01-16 | 2020-06-05 | 昂宝电子（上海）有限公司 | Line voltage detection circuit, system and method |
| CN111239465B (en) * | 2020-01-16 | 2023-05-23 | 昂宝电子（上海）有限公司 | Line voltage detection circuit, system and method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102769386B (en) | 2014-08-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108933533B (en) | The controller of incomplementarity active clamp flyback converter | |
| CN106059304B (en) | Switch with efficient voltage reduction using secondary switches | |
| US9246394B2 (en) | Synchronous rectification control circuit and power supply thereof | |
| KR101309293B1 (en) | Switching mode power supply and the driving method thereof | |
| US8094468B2 (en) | Control circuit having off-time modulation to operate power converter at quasi-resonance and in continuous current mode | |
| US7710095B2 (en) | Power converter having PWM controller for maximum output power compensation | |
| CN102655378B (en) | Isolated voltage converter circuit and control method thereof | |
| CN101710786B (en) | Switch voltage-stabilizing circuit and method | |
| CN105939098B (en) | Power supply, circuit and method with near valley switching | |
| CN103280995B (en) | Quasi-resonance converter synchronous rectification circuit | |
| CN102832806B (en) | Switching voltage stabilization circuit and voltage feedback circuit as well as voltage feedback method of voltage feedback circuit | |
| US10797583B2 (en) | Secondary winding sense for hard switch detection | |
| CN108418435B (en) | Synchronous rectification flyback DC-DC power supply conversion device | |
| KR101236955B1 (en) | Switching mode power supply and the driving method thereof | |
| CN104270008A (en) | Resonant switch converter, control circuit and control method for automatic dead-time regulation of control circuit | |
| CN103887984A (en) | Isolating converter and switching power supply comprising same | |
| KR20090084292A (en) | Resonant converter | |
| CN102594097A (en) | Switching power supply, and control circuit and control method thereof | |
| CN103095135A (en) | Switch convertor and slope compensating circuit thereof | |
| US11025170B2 (en) | Systems and methods for reducing switching loss in power conversion systems | |
| CN204089601U (en) | Resonance switch convertor and control circuit thereof | |
| US20220376629A1 (en) | Flyback converter and control method thereof | |
| CN202840946U (en) | Switch voltage stabilizing circuit and voltage feedback circuit thereof | |
| CN102769386B (en) | Switching converter and control circuit and control method thereof | |
| JP2012110117A (en) | Switching power supply apparatus |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |