CN204013219U - Control circuit for switching converter - Google Patents
Control circuit for switching converter Download PDFInfo
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- CN204013219U CN204013219U CN201420363892.7U CN201420363892U CN204013219U CN 204013219 U CN204013219 U CN 204013219U CN 201420363892 U CN201420363892 U CN 201420363892U CN 204013219 U CN204013219 U CN 204013219U
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Abstract
Disclosed is a control circuit for a switching converter, comprising: the circuit comprises an on signal generating circuit, an off signal generating circuit, a logic circuit, a current sensing circuit and an off threshold generating circuit. The control circuit generates a switching signal equal to or greater than a set frequency to drive a power switch of the switching converter.
Description
Technical field
Embodiment of the present utility model relates to electronic circuit, more specifically still not exclusively relates to a kind of control circuit for switching mode DC-DC transducer.
Background technology
DC-DC transducer is a kind of DC of acceptance input voltage the electronic device that DC output voltage is provided to load.DC-DC transducer is generally configured to based on providing adjusted DC output voltage or electric current (" load voltage " or " load current ") at some unadjusted DC source voltages to load.For example in the application of many automobiles (wherein battery provides the DC power source with approximate 12 volts of unadjusted voltages), DC-DC transducer can be used for receiving unadjusted 12 volts of DC as source voltage and adjusted DC output voltage is provided or electric current to drive various electronic circuits in vehicle (instrument, annex, engine control, lighting apparatus, radio/stereo etc.).DC output voltage can be recently lower, higher or identical from the source of battery voltage.Again for example in some illumination application, DC-DC transducer can be used for receiving unadjusted 12 volts of DC as source voltage and provide adjusted DC output current with driving LED.
The common control technology for DC-DC transducer has Average Current Control technology, peak current control technology and fixing ON time (COT) control technology etc.Average Current Control technology and peak current control technology can be so that dc-dc converter obtain output voltage or output current accurately, but its loop compensation is complicated, and transient response is poor.Use the dc-dc converter of COT control technology can not need loop compensation network, thereby make circuit design simpler, but its frequency easily changes with input and output voltage or load current.For this reason, how obtaining more optimal control circuit and control method is the difficult problem that those skilled in the art face.
Utility model content
For addressing the above problem, the utility model provides a kind of control circuit for dc-dc converter, described dc-dc converter has at least one power switch, described control circuit comprises: Continuity signal produces circuit, there is first input end, the second input and output, comparative result based on reference signal and feedback signal provides Continuity signal at output, and wherein said feedback signal reflects load current or the output voltage of described dc-dc converter; Cut-off signals produces circuit, has first input end, the second input and output, and the comparative result based on turn-offing threshold value and current sensing signal provides cut-off signals at output; Logical circuit, has first input end, the second input and output, based on described Continuity signal and described cut-off signals, at output, provides switching signal; Current sensing circuit, has input and output, and the electric current based on described power switch produces described current sensing signal; Turn-off threshold value and produce circuit, have input and output, the frequency based on switching signal and setpoint frequency are adjusted described shutoff threshold value, make the frequency of described switching signal be equal to, or greater than in fact described setpoint frequency.
According to an embodiment of the present utility model, described switching signal is for controlling the turn-on and turn-off of described power switch, and described power switch is the main switch of BUCK circuit.
According to an embodiment of the present utility model, described power switch has first end, the second end and control end, wherein first end receives input voltage, control end receives described switching signal, described dc-dc converter also comprises: inferior switching tube, there is first end, the second end and control end, and wherein first end is coupled to the second end of described power switch, the second end ground connection, control end is coupled to described logical circuit; And inductor, there is first end and the second end, wherein first end is electrically coupled to the second end of described power switch and the first end of time switching tube, and its second end provides described output voltage.
According to an embodiment of the present utility model, described Continuity signal produces circuit and comprises the first comparator, described the first comparator comprises first input end, the second input and output, is configured to respectively first input end, the second input and output that described Continuity signal produces circuit.
According to an embodiment of the present utility model, described Continuity signal produces circuit and comprises: the first amplifier, comprise first input end, the second input and output, its first input end and the second input are configured to respectively first input end and second input of described turning circuit; And first comparator, comprise first input end, the second input and output, its first input end is coupled to the output of described the first amplifier, its second input is coupled to the second input of described the first amplifier, and its output is configured to the output that described Continuity signal produces circuit.
According to an embodiment of the present utility model, described current sensing circuit comprises current detection circuit, and described current detection circuit detects the electric current flowing through on described power switch, powers on to miscarry give birth to described shutoff threshold signal based on described power switch.
According to an embodiment of the present utility model, described current sensing circuit comprises current analog circuit, described in described current analog electric circuit inspection, the voltage of power switch one end or described power switch first end and the second terminal voltage is poor, simulates the electric current that flows through on described power switch to produce described shutoff threshold signal.
According to an embodiment of the present utility model, in described shutoff threshold value, produce circuit and comprise phase-locked loop, described phase-locked loop receives reference frequency signal and described switching signal, and the difference in the cycle based on described reference clock signal and described switching signal or the difference of frequency produce described shutoff threshold signal.
According to an embodiment of the present utility model, in described shutoff threshold value, produce circuit and comprise: the first electric capacity, there is first end and the second end, its second end is coupled to ground; The first switch, has first end, the second end and control end, and its first end is coupled to the first voltage by the first current source, and its second end couples the first end of described the first electric capacity; Second switch, has first end, the second end and control end, and its first end couples the first end of described the first electric capacity, and its second end is coupled to described earth potential; The second electric capacity, has first end and the second end, and its second end is coupled to ground; The 3rd switch, has first end, the second end and control end, and its first end is coupled to second voltage by the second current source, and its second end is coupled to the first end of described the second electric capacity; The 4th switch, has first end, the second end and control end, and its first end couples the first end of described the first electric capacity, and its second end is coupled to described earth potential by the 3rd current source; The second comparator, has first input end, the second input and output, and its first input end is coupled to the first end of described the first electric capacity, and its second input receives the second reference signal; And second logical circuit, there is first input end, the second input, the first output and the second output, its first input end is coupled to the output of described the second comparator, its second input receives described switching signal, and its output provides a plurality of control signals to control the turn-on and turn-off of described first to fourth switch.
According to an embodiment of the present utility model, described the second logical circuit also comprises pulse-generating circuit, and the spike signal identical with described switching signal frequency is provided.
According to an embodiment of the present utility model, described control signal comprises the first control signal and the second control signal, wherein said the first control signal is turn-offed in order to control the conducting of described the first switch and described the 3rd switch, and described the second control signal is turn-offed in order to control the conducting of described second switch and described the 4th switch.
According to an embodiment of the present utility model, described shutoff threshold value produces circuit and also comprises clamp circuit, in order to set the maximum of described shutoff threshold value.
According to an embodiment of the present utility model, when described shutoff threshold signal is less than clamp voltage, the frequency of described switching signal equals described setpoint frequency; Described shutoff threshold signal by described clamp circuit clamper after, the frequency of described switching signal is greater than described setpoint frequency.
The advantages such as the control circuit for dc-dc converter that the utility model provides has simple in structure, and transient response is fast, can also enter audiorange to prevent operating frequency for the minimum frequency of operation of dc-dc converter is set.
Accompanying drawing explanation
The utility model will illustrate by example and with reference to the mode of accompanying drawing, wherein:
Fig. 1 illustrates a according to the circuit diagram of the dc-dc converter 10 of an enforcement of the utility model;
Fig. 2 illustrates a according to the circuit diagram of the phase lock circuitry 200 of an embodiment of the present utility model;
Fig. 3 illustrates the oscillogram in dc-dc converter 10 runnings;
Fig. 4 illustrates a according to the circuit diagram of the dc-dc converter 40 of an enforcement of the utility model;
Fig. 5 illustrates the circuit diagram that a shutoff threshold value according to an enforcement of the utility model produces circuit 405;
Fig. 6 illustrates the oscillogram in dc-dc converter 40 runnings;
Fig. 7 illustrates and adopts the oscillogram of dc-dc converter 40 under underload and heavy duty after clamp circuit CLAMP; And
Fig. 8 illustrates a according to the circuit diagram of the dc-dc converter 80 of an enforcement of the utility model.
Embodiment
Specific embodiment hereinafter described represents exemplary embodiment of the present utility model, and in essence only for example explanation is unrestricted.In specification, mention that " embodiment " or " embodiment " mean in conjunction with the described special characteristic of this embodiment, structure or characteristic to be included at least one embodiment of the present utility model.Term " in one embodiment " each position in specification occurs all not relating to identical embodiment, neither mutually get rid of other embodiment or variable embodiment.Disclosed all features in this specification, or the step in disclosed all methods or process, except mutually exclusive feature and/or step, all can combine by any way.
Describe below with reference to the accompanying drawings embodiment of the present utility model in detail.Run through institute's identical Reference numeral of drawings attached and represent identical parts or feature.
Fig. 1 illustrates a according to the circuit diagram of the dc-dc converter 10 of an enforcement of the utility model.Dc-dc converter 10 comprises control circuit 100 and switching circuit 110.
Switching circuit 110 comprises at least one power switch M1, and power switch M1 has control end, first end and the second end.Under the effect of control signal CTRL, switching circuit 110 is converted to output voltage VO UT by input voltage VIN.The topological structures such as switching circuit 110 can have various topological structures, structure and normal shock or the flyback of boosting such as Buck type buck configuration, Boost type.
Control circuit 100 comprises that Continuity signal produces circuit 101, cut-off signals produces circuit 102, logical circuit 103, current sensing circuit 104 and turn-offs threshold value and produces circuit 105.
Continuity signal produces circuit 101, has first input end, the second input and output, and the comparative result based on reference signal VREF and output voltage VO UT provides Continuity signal ONSET at output.In another embodiment, Continuity signal produces circuit 101 and can also at output, provide Continuity signal ONSET with the comparative result that characterizes the voltage signal of load current IOUT based on reference signal VREF.
Cut-off signals produces circuit 102, has first input end, the second input and output, and the comparative result based on turn-offing threshold value OFFTH and current sensing signal RFLTI provides cut-off signals OFFSET at output.
Logical circuit 103, has first input end, the second input and output, based on Continuity signal ONSET and cut-off signals OFFSET, at output, provides switching signal CTRL.
Current sensing circuit 104, has input and output, and its input is coupled to one end of power switch M1, the electric current I M1 generation current sensing signal RFLTI during based on power switch M1 conducting.In one embodiment, the electric current I M1 of current sensing circuit 104 sense switch pipe M1, zooms in or out electric current I M1, then optionally the current signal after amplifying is converted to voltage signal and usings as current sensing signal RFLTI.In another embodiment, turn-off the variation that threshold value produces the electric current I M1 of the voltage that circuit 104 can also be based on switching tube M1 (first end voltage, the second terminal voltage or both end voltage poor) simulation, virtual or matching power switch M1, using and produce the voltage signal that is directly proportional to electric current I M1 or current signal as current sensing signal RFLTI.
Turn-off threshold value and produce circuit 105, have input and output, the frequency based on switching signal CTRL and setpoint frequency FQREF adjust and turn-off threshold value OFFTH, make the frequency of switching signal CTRL equal in fact setpoint frequency FQREF.Fig. 2 illustrates the circuit diagram that produces circuit 200 according to the shutoff threshold value of the utility model embodiment, turn-off threshold value generation circuit 200 and comprise a phase-locked loop pll, this PLL has first input end with reception control signal CTRL, first input end is to receive reference clock signal CLK, poor based on control signal CTRL and reference clock signal CLK frequency, provides and turn-offs threshold value OFFTH at output.
Fig. 3 illustrates according to the oscillogram in dc-dc converter 20 runnings of the utility model embodiment.At a time, when output voltage VO UT is during lower than reference voltage VREF, the Continuity signal ONSET that Continuity signal produces the output of circuit 101 is high level by low transition, and the switching signal CTRL of logical circuit 103 outputs is that high level is to open power switch M1 by low transition.After power switch M1 opens, the electric current I M1 of power switch continues to increase, and current sensing signal RFLTI also increases thereupon, and when current sensing signal RFLTI increases to shutoff threshold signal OFFSET, power switch M1 closes.The frequency of shutoff threshold value generation circuit 105 comparison switching signal CTRL is poor with (clock signal clk) setpoint frequency FQREF's, turn-offs threshold value OFFTH make the frequency of switching signal CTRL equal in fact setpoint frequency FQREF by adjustment.In Fig. 3, power switch M1 ends the stage, and current sensing signal RFLTI can slowly reduce, and as dotted line in Fig. 3 represents, also can reduce rapidly.
Fig. 4 illustrates a according to the circuit diagram of the dc-dc converter 40 of an enforcement of the utility model.Dc-dc converter 40 comprises control circuit 400 and switching circuit 410.Switching circuit 410 has adopted synchronous buck transformation topology, comprises main switch M1, inferior switching tube M2, inductor L and output capacitor C.Switching circuit 410, by conducting and the shutoff of switching tube M1 and M2, is converted to output voltage VO UT by input voltage VIN.One end of main switch M1 receives input voltage VIN, and the other end is electrically coupled to one end of time switching tube M2.The other end ground connection of inferior switching tube M2.One end of inductor L is electrically coupled to the link of switching tube M1 and M2, and output capacitor COUT electric coupling is between the other end and ground of inductor L.The voltage at output capacitor COUT two ends is output voltage VO UT.
Control circuit 400 comprises that Continuity signal produces circuit 401, cut-off signals produces circuit 402, logical circuit 403, current sensing circuit 404 and turn-offs threshold value and produces circuit 405.
Continuity signal produces circuit 401 and comprises comparator C OM1, and comparator C OM1 has first input end, the second input and output, and the comparative result based on reference signal VREF and feedback signal VFB provides Continuity signal ONSET at output.In the embodiment shown in Figure 2, resistance R F1 and RF2 form sample circuit with sampling and outputting voltage VOUT and feedback signal VFB are provided.In other embodiments, feedback signal VFB can also reflect the load current IOUT of dc-dc converter 40.
Cut-off signals produces circuit 402 and comprises comparator C OM2, and comparator C OM2 has first input end, the second input and output, and the comparative result based on turn-offing threshold value OFFTH and current sensing signal RFLTI provides cut-off signals OFFSET at output.
Logical circuit 403 comprises rest-set flip-flop RS1, there is first input end S to receive Continuity signal ONSET, the second input R to receive cut-off signals OFFSET and output Q, based on Continuity signal ONSET and cut-off signals OFFSET, at output Q, provide switching signal CTRL.
Current sensing circuit 404, has input and output, and its input is coupled to one end of main switch M1, the electric current I M1 generation current sensing signal RFLTI based on main switch M1.In one embodiment, current sensing circuit 404 detects the electric current I M1 of main switch M1, and electric current I M1 is zoomed in or out, and then optionally the current signal after amplifying is converted to voltage signal and usings as current sensing signal RFLTI.When main switch M1 conducting, the electric current I M1 in inductance L equals inductive current I L.For this reason, can obtain by detecting inductive current IL the electric current I M1 of main switch M1, and this equivalent way is no more than protection range of the present utility model.
Turn-off threshold value and produce circuit 405, have input and output, the frequency based on switching signal CTRL and setpoint frequency FQREF adjust and turn-off threshold value OFFTH, make the frequency of switching signal CTRL equal in fact setpoint frequency FQREF.
Fig. 5 illustrates the circuit diagram that produces circuit 405 according to the shutoff threshold value of the utility model embodiment, turn-offs threshold value generation circuit 405 and comprises first to fourth current source I1～I4, the first capacitor C 1, the first switch S 1, second switch S2, the second capacitor C 2, the 3rd switch S 3, the 4th switch S 4, comparator C OM3 and logical circuit 501.The first capacitor C 1, has first end and the second end, and its second end is coupled to earth potential GND.The first switch S 1, has first end, the second end and control end, and its first end is coupled to the first voltage V1 by the first current source I1, and its second end is coupled to the first end of the first capacitor C 1.Second switch S2, has first end, the second end and control end, and its first end couples the first end of the first capacitor C 1, and its second end is coupled to earth potential GND.The second capacitor C 2, has first end and the second end, and its second end is coupled to earth potential GND.The 3rd switch S 3, has first end, the second end and control end, and its first end is coupled to second voltage V2 by the second current source I2, and its second end couples the first end of the second capacitor C 2, and wherein second voltage V2 can equal the first voltage V1.The 4th switch S 4, has first end, the second end and control end, and its first end couples the first end of the first capacitor C 1, and its second end is coupled to earth potential GND by the 3rd current source I3.Comparator C OM3, has first input end, the second input and output, and its first input end is coupled to the first end of the first capacitor C 1, and its second termination is received the second reference signal VREF2; Logical circuit 501, there is first input end, the second input, the first output and the second output, its first input end is coupled to the output of comparator C OM3, its second input couples receiving key signal CTRL, and its output provides a plurality of control signals to control the turn-on and turn-off of first to fourth switch S 1～S4.
In one embodiment, the second logical circuit U2 comprises rest-set flip-flop, have first input end S with receiving key signal CTRL, the second input R to receive output signal and the output Q of comparator C OM3.Logical circuit 501 can also optionally comprise pulse-triggered unit 502, there is input and output, input receiving key signal CTRL, rising edge based on switching signal or trailing edge provide pulse signal PULSE at output, and its output is coupled to the first input end S of logical circuit 501.
Fig. 6 illustrates according to the oscillogram in dc-dc converter 40 runnings of the utility model embodiment.At a time, when feedback voltage FB is during lower than reference voltage VREF, the Continuity signal ONSET that Continuity signal produces the output of circuit 401 is high level by low transition, and the switching signal CTRL of logical circuit 403 outputs is that high level is to open main switch M1 by low transition.
The T1 stage as shown in Figure 6, after main switch M1 opens, the electric current I M1 on main switch continues to increase, the increase that current sensing signal RFLTI agrees to, when RFLII increases to OFFSET, switching signal CTRL is converted to low level to close main switch M1 by high level.Simultaneously, the trailing edge of switching signal CTRL is by set the second logical circuit 501, make the first output Q output high level of the second logical circuit 501 with closed (conducting) switch S 1 and S3, the second output QN output low level is to open (not conducting) switch S 2 and S4.
In the T2 stage as shown in Figure 6, after switch S 1 and S3 conducting, capacitor C 1 both end voltage VC1 and capacitor C 2 both end voltage VC2 are by rising.When VC1 is elevated to the second reference voltage VREF2, can there is state turnover in the output voltage of comparator C OM3, by low level upset, is that high level is with reseting logic circuit 501.After reset, the first output Q output high level of logical circuit 501 is to open (not conducting) switch S 1 and S3, and the second output QN output low level is with closed (conducting) switch S 2 and S4.
In the T3 stage as shown in Figure 6, after switch S 2 and S4 conducting, the voltage VC1 of capacitor C 1 will will be zero fast, and capacitor C 2 will slowly be discharged by S4 and the 4th current source I4, and VC2 reduces gradually.
In T2 or T3 stage, due to main switch, M1 closes, output voltage VO UT can reduce gradually, when feedback voltage FB is during lower than reference voltage VREF, the Continuity signal ONSET that Continuity signal produces the output of circuit 401 is high level by low transition, and the switching signal CTRL of logical circuit 403 outputs is that high level is to open main switch M1 by low transition.After main switch M1 opens, the electric current I M1 on power switch continues to increase, the increase that current sensing signal RFLTI agrees to.In T3 stage Mo, the increase that current sensing signal RFLTI agrees to, and the voltage VC2 that is configured to turn-off threshold value OFFSET constantly reduces, when RFLTI increases to OFFSET, switching signal CTRL is converted to low level to close main switch M1 by high level.
Thereby said process constantly repeats to make output voltage VO UT be stabilized in setting output voltage.
In some embodiment, turn-off threshold value generation circuit 405 and can also comprise clamp circuit CLAMP, clamp circuit can be by the maximum voltage limit of VC2 at a clamp voltage value VCLAP.Fig. 7 illustrates the oscillogram under underload and heavy duty according to the dc-dc converter 40 of an enforcement of the utility model.As shown in Figure 70 1, under light load condition, the maximum of voltage VC2 is lower than clamp voltage VCLAP, and when load current IOUT increases, current sensing signal RFLTI and VC2 all increase, and move closer to clamp voltage VCLAP.Maximum voltage at VC2 is limited in after clamp voltage VCLAP, under fixing inductance, input voltage VIN and output voltage VO U T condition, main switch M1 (inductance in other words) average current IAV1 also will fix, and make dc-dc converter 40 possibly cannot provide enough load currents.For enough load currents are provided, dc-dc converter 40 can be heightened the frequency of switching signal CTRL.As shown in Figure 70 2, after frequency increases, the main switch M1 curent change cycle reduces, and main switch M1 average current is increased, thereby enough load currents can be provided.When load reduces again, system will reduce frequency, and minimum being reduced to turn-offed the frequency that threshold value produces circuit 405 settings, thereby avoids switching frequency to enter audiorange.In like manner, clamp circuit CLAMP can also be for the output of the phase-locked loop pll shown in Fig. 2, so that the minimal switching frequency of the dc-dc converter shown in Fig. 1 10 is set in to reference clock frequency FQREF.Adopt after clamp circuit CLAMP, when during underload, cut-off current changes, turn-off threshold value and produce frequency and the setpoint frequency FQREF adjustment shutoff threshold value OFFTH of circuit 405 based on switching signal CTRL, make the frequency of switching signal CTRL equal in fact setpoint frequency FQREF.Under heavy duty, turn-off threshold value OFFTH by clamper, system by the frequency that improves switching signal CTRL so that enough load currents to be provided.
Fig. 8 illustrates a according to the circuit diagram of the dc-dc converter 80 of an enforcement of the utility model.Dc-dc converter 80 comprises control circuit 800 and switching circuit 410.Compare with the control circuit 400 shown in Fig. 4, control circuit 800 further comprises the first amplifier 810.The first amplifier 801, comprise first input end, the second input and output, its first input end is configured to the first input end of described turning circuit control circuit to receive reference signal VREF, its second input is configured to the second input of described turning circuit control circuit with receiving feedback signals VFB, and its output provides error amplification signal VEA.The first input end of the first comparator C OM1 is coupled to the output of the first amplifier 801, its second input receiving feedback signals VFB, and its output is configured to the output of described turning circuit.The first amplifier 710 can improve the load regulation of dc-dc converter 80 and output voltage (or electric current) precision well.
Although the utility model is described in conjunction with its concrete illustrative embodiments, it should be apparent that, multiple alternative, revise and distortion is apparent for those skilled in the art.Thus, the illustrative embodiments of the present utility model of illustrating at this is schematically and also non-limiting.Can in the situation that not departing from spirit and scope of the present utility model, modify.
The measure word that used in this disclosure " one ", " a kind of " etc. do not get rid of plural number." first " in literary composition, " second " etc. are only illustrated in the sequencing occurring in the description of embodiment, so that distinguish like." first ", " second " appearance in claims are only for the ease of to the fast understanding of claim rather than in order to be limited.Any Reference numeral in claims all should not be construed as the restriction to scope.
Claims (13)
1. for a control circuit for dc-dc converter, described dc-dc converter has at least one power switch, and described control circuit comprises:
Continuity signal produces circuit, there is first input end, the second input and output, comparative result based on reference signal and feedback signal provides Continuity signal at output, and wherein said feedback signal reflects load current or the output voltage of described dc-dc converter;
Cut-off signals produces circuit, has first input end, the second input and output, and the comparative result based on turn-offing threshold signal and current sensing signal provides cut-off signals at output;
Logical circuit, has first input end, the second input and output, based on described Continuity signal and described cut-off signals, at output, provides switching signal;
Current sensing circuit, has input and output, and the electric current based on described power switch produces described current sensing signal;
Turn-off threshold value and produce circuit, have input and output, the frequency based on described switching signal and setpoint frequency are adjusted described shutoff threshold value, make the frequency of described switching signal be equal to, or greater than in fact described setpoint frequency.
2. control circuit according to claim 1, is characterized in that, described switching signal is for controlling the turn-on and turn-off of described power switch, and described power switch is the main switch of BUCK circuit.
3. control circuit according to claim 1, is characterized in that, described power switch has first end, the second end and control end, and wherein first end receives input voltage, and control end receives described switching signal, and described dc-dc converter also comprises:
Inferior switching tube, has first end, the second end and control end, and wherein first end is coupled to the second end of described power switch, the second end ground connection, and control end is coupled to described logical circuit; And
Inductor, has first end and the second end, and wherein first end is electrically coupled to the second end of described power switch and the first end of time switching tube, and its second end provides described output voltage.
4. control circuit according to claim 1, it is characterized in that, described Continuity signal produces circuit and comprises the first comparator, described the first comparator comprises first input end, the second input and output, is configured to respectively first input end, the second input and output that described Continuity signal produces circuit.
5. control circuit according to claim 1, is characterized in that, described Continuity signal produces circuit and comprises:
The first amplifier, comprises first input end, the second input and output, and its first input end and the second input are configured to respectively first input end and second input of described turning circuit; And
The first comparator, comprise first input end, the second input and output, its first input end is coupled to the output of described the first amplifier, and its second input is coupled to the second input of described the first amplifier, and its output is configured to the output that described Continuity signal produces circuit.
6. control circuit according to claim 1, it is characterized in that, in described shutoff threshold value, produce circuit and comprise phase-locked loop, described phase-locked loop receives reference frequency signal and described switching signal, and the difference in the cycle based on described reference clock signal and described switching signal or the difference of frequency produce described shutoff threshold signal.
7. control circuit according to claim 1, is characterized in that, produces circuit comprise in described shutoff threshold value:
The first electric capacity, has first end and the second end, and its second end is coupled to ground;
The first switch, has first end, the second end and control end, and its first end is coupled to the first voltage by the first current source, and its second end couples the first end of described the first electric capacity;
Second switch, has first end, the second end and control end, and its first end couples the first end of described the first electric capacity, and its second end is coupled to described earth potential;
The second electric capacity, has first end and the second end, and its second end is coupled to ground;
The 3rd switch, has first end, the second end and control end, and its first end is coupled to second voltage by the second current source, and its second end is coupled to the first end of described the second electric capacity;
The 4th switch, has first end, the second end and control end, and its first end couples the first end of described the first electric capacity, and its second end is coupled to described earth potential by the 3rd current source;
The second comparator, has first input end, the second input and output, and its first input end is coupled to the first end of described the first electric capacity, and its second input receives the second reference signal; And
The second logical circuit, there is first input end, the second input, the first output and the second output, its first input end is coupled to the output of described the second comparator, its second input receives described switching signal, and its output provides a plurality of control signals to control the turn-on and turn-off of described first to fourth switch.
8. control circuit according to claim 7, is characterized in that, described the second logical circuit also comprises pulse-generating circuit, and the spike signal identical with described switching signal frequency is provided.
9. control circuit according to claim 7, it is characterized in that, described control signal comprises the first control signal and the second control signal, wherein said the first control signal is turn-offed in order to control the conducting of described the first switch and described the 3rd switch, and described the second control signal is turn-offed in order to control the conducting of described second switch and described the 4th switch.
10. according to the control circuit described in claim 6 or 7, it is characterized in that, described shutoff threshold value produces circuit and also comprises clamp circuit, in order to set the maximum of described shutoff threshold value.
11. control circuits according to claim 10, is characterized in that, when described shutoff threshold signal is less than clamp voltage, the frequency of described switching signal equals described setpoint frequency; Described shutoff threshold signal by described clamp circuit clamper after, the frequency of described switching signal is greater than described setpoint frequency.
12. control circuits according to claim 1, it is characterized in that, described current sensing circuit comprises current detection circuit, and described current detection circuit detects the electric current flowing through on described power switch, powers on to miscarry give birth to described shutoff threshold signal based on described power switch.
13. control circuits according to claim 1, it is characterized in that, described current sensing circuit comprises current analog circuit, described in described current analog electric circuit inspection, the voltage of power switch one end or described power switch first end and the second terminal voltage is poor, simulates the electric current that flows through on described power switch to produce described shutoff threshold signal.
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|---|---|---|---|
| CN201420363892.7U CN204013219U (en) | 2014-07-02 | 2014-07-02 | Control circuit for switching converter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104201883A (en) * | 2014-07-02 | 2014-12-10 | 成都芯源系统有限公司 | Control circuit for switching converter |
| CN108418404A (en) * | 2018-03-29 | 2018-08-17 | 深圳茂硕电子科技有限公司 | It is a kind of to enter the controllable circuit of interval point and its method |
-
2014
- 2014-07-02 CN CN201420363892.7U patent/CN204013219U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104201883A (en) * | 2014-07-02 | 2014-12-10 | 成都芯源系统有限公司 | Control circuit for switching converter |
| CN104201883B (en) * | 2014-07-02 | 2017-02-15 | 成都芯源系统有限公司 | Control circuit for switching converter |
| CN108418404A (en) * | 2018-03-29 | 2018-08-17 | 深圳茂硕电子科技有限公司 | It is a kind of to enter the controllable circuit of interval point and its method |
| CN108418404B (en) * | 2018-03-29 | 2024-01-30 | 深圳茂硕电子科技有限公司 | Circuit capable of controlling intermittent point entering and method thereof |
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