CN202475254U - Switch converter and control circuit thereof - Google Patents

Switch converter and control circuit thereof Download PDF

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Publication number
CN202475254U
CN202475254U CN2012201204163U CN201220120416U CN202475254U CN 202475254 U CN202475254 U CN 202475254U CN 2012201204163 U CN2012201204163 U CN 2012201204163U CN 201220120416 U CN201220120416 U CN 201220120416U CN 202475254 U CN202475254 U CN 202475254U
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output
signal
input
coupled
slope compensation
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CN2012201204163U
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姜礼节
吴小康
欧阳茜
罗苏华
任远程
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Chengdu Monolithic Power Systems Co Ltd
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Chengdu Monolithic Power Systems Co Ltd
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Abstract

Switching converter and control circuit thereof, this control circuit includes: the device comprises a conduction time control unit, a slope compensation unit, a comparison unit, a logic unit and a load detection unit, wherein the slope compensation unit is also provided with an input end which is coupled to the output end of the load detection unit to receive a detection signal, and the slope compensation unit adjusts the slope compensation signal according to the detection signal. By adjusting the slope compensation signal according to the load state, the overshoot of the output voltage of the switching converter when the load current drops instantaneously is reduced while the working stability of the switching converter is maintained, and the transient response of the switching converter is improved.

Description

Switch converters and control circuit thereof
Technical field
The embodiment of the utility model relates to electronic circuit, relates in particular to a kind of switch converters and control circuit thereof.
Background technology
Constant ON time control has obtained good application because its superior load transient response, simple internal construction and level and smooth mode of operation are switched in field of power supplies.
Fig. 1 is the block diagram of the switch converters 100 of the constant ON time control of existing employing.Switch converters 100 comprises ON time control unit 101, comparing unit 102, logical block 103 and switching circuit 104.Switching circuit 104 comprises at least one switching tube, and the conducting through this at least one switching tube converts input voltage VIN into output voltage VO UT with turn-offing.ON time control unit 101 produces ON time control signal COT, with the conducting duration of one or more switching tubes in the control switch circuit 104.Comparing unit 102 is coupled to the output of switching circuit 104, output voltage VO UT and reference signal VREF is compared, to produce comparison signal SET.Logical block 103 is coupled to the output of ON time control unit 101 and comparing unit 102, produces control signal CTRL according to ON time control signal COT and comparison signal SET, with the conducting and the shutoff of at least one switching tube in the control switch circuit 104.
In switching circuit 104 the equivalent series resistance value of output capacitor hour, output voltage VO UT may produce subharmonic oscillation, causes switch converters 100 job insecurities.In order to prevent the generation of this subharmonic oscillation, switch converters 100 also comprises slope compensation unit 105 usually.Slope compensation unit 105 produces slope compensation signal VSLOPE and it is provided to comparing unit 102.Comparing unit 102 produces control signal CTRL according to reference signal VREF, output voltage VO UT and slope compensation signal VSLOPE.
In order to guarantee that switch converters all can keep stable under various states, the slope of slope compensation signal VSLOPE must be enough big, for example greater than a critical value by switching frequency, duty ratio and output capacitor decision.Yet the slope compensation signal VSLOPE of high slope can cause adverse effect to the transient response of switch converters.
The utility model content
The technical problem that the utility model will solve provides a kind of working stability and good switch converters and the control circuit thereof of transient response.
A kind of control circuit that is used for switch converters according to the utility model embodiment; This switch converters comprises the switching circuit with at least one switching tube; It is characterized in that; This control circuit comprises: the ON time control unit, have output, and produce the ON time control signal at output; The slope compensation unit has output, produces slope compensation signal at output; Comparing unit; Have first input end, second input, the 3rd input and output; Wherein first input end receives reference signal, and second input is coupled to the output voltage of the output of switching circuit with the receiving key circuit, and the 3rd input is coupled to the output of slope compensation unit to receive slope compensation signal; Comparing unit produces comparison signal based on reference signal, output voltage and slope compensation signal at output; Logical block; Have first input end, second input and output; Wherein first input end be coupled to the ON time control unit output to receive the ON time control signal, second input is coupled to the output of comparing unit to receive comparison signal, logical block is according to ON time control signal and comparison signal; Produce control signal at output, with the conducting and the shutoff of at least one switching tube in the control switch circuit; And the load detecting unit, have output, detect load condition and produce detection signal at output; Wherein the slope compensation unit also has input, and this input is coupled to the output of load detecting unit to receive detection signal, and the slope compensation unit is regulated slope compensation signal according to detection signal.
In one embodiment, descend if the load detecting unit detects load current, the slope compensation unit is reseted slope compensation signal and/or the slope of slope compensation signal is reduced.
In one embodiment, the slope compensation unit comprises: controllable current source, have first end, second end and control end, and wherein first end is coupled to supply power voltage; The first transistor has first end, second end and control end, and wherein first end is coupled to second end of controllable current source; Capacitor has first end and second end, and wherein first end is coupled to second end of the first transistor; Transistor seconds has first end, second end and control end, and wherein first end is coupled to second end of the first transistor and first end of capacitor, and second end is coupled to second end of capacitor.
In one embodiment; Comparing unit comprises comparator; This comparator has first input end, second input and output; Wherein first input end receives the poor of reference signal and slope compensation signal, and the output that second input is coupled to switching circuit is with the reception output voltage or represent the feedback signal of output voltage, and output provides comparison signal.
In one embodiment; This control circuit also comprises: pi element; Have first input end, second input and output, wherein first input end receives reference signal, and second input is coupled to the output of switching circuit to receive output voltage; Pi element produces the proportional integral signal based on reference signal and output voltage at its output; Adder; Have first input end, second input and output; Wherein first input end receives reference signal, and second input is coupled to the output of pi element to receive the proportional integral signal, and output is coupled to comparing unit so that reference signal and proportional integral signal sum to be provided.
In one embodiment, the load detecting unit compares the switch periods under current switch periods and the stable state, descends if current switch periods than long certain proportion of switch periods under the stable state or numerical value, then is regarded as detecting load current.
In one embodiment, the load detecting unit detects load current, and the preset value if load current descends then is regarded as detecting load current and descends.
In one embodiment, the output voltage of load detecting unit sense switch circuit if output voltage rises to a preset value, then is regarded as detecting load current and descends.
A kind of switch converters according to the utility model embodiment is characterized in that, comprising: switching circuit, comprise at least one switching tube, and the conducting through this at least one switching tube converts input voltage into output voltage with turn-offing; And foregoing control circuit.
In one embodiment, said switching circuit comprises: first switching tube, have first end, second end and control end, and wherein first termination is received input voltage, and control end is coupled to logical block to receive control signal; The second switch pipe has first end, second end and control end, and wherein first end is coupled to second end of first switching tube, the second end ground connection, and control end is coupled to logical block to receive control signal; Inductor has first end and second end, and wherein first end is coupled to second end of first switching tube and first end of second switch pipe; And output capacitor, be coupled between second end and ground of inductor.
Embodiment according to the utility model; Through slope compensation signal being regulated according to load condition; In maintained switch converter working stability, reduced the overshoot on the switch converters output voltage when the instantaneous decline of load current, improved the transient response of switch converters.
Description of drawings
Fig. 1 is the block diagram of the switch converters 100 of the constant ON time control of existing employing;
Fig. 2 is the block diagram according to the switch converters 200 of the utility model one embodiment;
Fig. 3 is the circuit theory diagrams according to the switch converters 300 of the utility model one embodiment;
Fig. 4 is switch converters shown in Figure 3 300 oscillogram in normal operation according to the utility model one embodiment;
Fig. 5 is the oscillogram of existing switch converters when the instantaneous decline of load current;
Fig. 6 is according to the switch converters shown in Figure 3 300 of the utility model one embodiment oscillogram when the instantaneous decline of load current;
Fig. 7 is according to the switch converters shown in Figure 3 300 of another embodiment of the utility model oscillogram when the instantaneous decline of load current;
Fig. 8 is according to the switch converters shown in Figure 3 300 of the another embodiment of the utility model oscillogram when the instantaneous decline of load current;
Fig. 9 is the circuit theory diagrams according to the slope compensation unit of the utility model one embodiment;
Figure 10 is the circuit theory diagrams according to the slope compensation unit of another embodiment of the utility model;
Figure 11 is the circuit theory diagrams according to the slope compensation unit of the another embodiment of the utility model;
Figure 12 is the circuit theory diagrams according to the slope compensation unit of the utility model one embodiment.
Embodiment
To describe the specific embodiment of the utility model below in detail, should be noted that the embodiments described herein only is used to illustrate, be not limited to the utility model.In the following description, for the thorough to the utility model is provided, a large amount of specific detail have been set forth.Yet it is obvious that for those of ordinary skills: needn't adopt these specific detail to carry out the utility model.In other instances,, do not specifically describe known circuit, material or method for fear of obscuring the utility model.
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 utility model.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 be with any suitable combination and or sub the combination specific characteristic, 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 accompanying drawing that provides all be for illustrative purposes, and accompanying drawing 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 according to the switch converters 200 of the utility model one embodiment, comprises control circuit and switching circuit 204.Switching circuit 204 comprises at least one switching tube, and the conducting through this at least one switching tube converts input voltage VIN into output voltage VO UT with turn-offing.Switching circuit 204 can adopt any DC-DC or ac/dc transformation topology structure, for example synchronous or asynchronously boosts, buck converter, and normal shock, anti exciting converter or the like.Switching tube in the switching circuit 204 can be any controllable semiconductor switch device, for example mos field effect transistor (MOSFET), igbt (IGBT) etc.
Control circuit comprises ON time control unit 201, comparing unit 202, logical block 203, slope compensation unit 205 and load detecting unit 206.ON time control unit 201 produces ON time control signal COT, with the conducting duration of switching tube in the control switch circuit 204.Slope compensation unit 205 produces slope compensation signal VSLOPE.Comparing unit 202 is coupled to slope compensation unit 205 and switching circuit 204, based on the output voltage VO UT of slope compensation signal VSLOPE, reference signal VREF and switching circuit, produces comparison signal SET.Logical block 203 is coupled to ON time control unit 201 and comparing unit 202, produces control signal CTRL according to ON time control signal COT and comparison signal SET, with the conducting and the shutoff of at least one switching tube in the control switch circuit 204.
Load detecting unit 206 detects load condition and produces detection signal DEC.Slope compensation unit 205 is coupled to load detecting unit 206 with reception detection signal DEC, and according to detection signal DEC slope compensation signal VSLOPE is regulated.In one embodiment, if load detecting unit 206 detects the negative saltus step of load, i.e. the instantaneous decline of load current, then the 205 couples of slope compensation signal VSLOPE in slope compensation unit regulate.
In one embodiment, load detecting unit 206 compares the switch periods under current switch periods and the stable state, if current switch periods than long certain proportion of switch periods under the stable state or numerical value, then is regarded as detecting the instantaneous decline of load current.In another embodiment, load detecting unit 206 detects load current, and the preset value if load current descends then is regarded as detecting the instantaneous decline of load current.In yet another embodiment, the output voltage VO UT of load detecting unit 206 sense switch circuit 204 if output voltage VO UT rises to a preset value, then is regarded as detecting the instantaneous decline of load current.It will be understood by those skilled in the art that load detecting unit 206 also can detect load condition through detecting other parameters relevant with load current, these detection modes all do not break away from the protection range of the utility model.
In one embodiment; If load detecting unit 206 detects the instantaneous decline of load current; Slope compensation signal VSLOPE is reseted in slope compensation unit 205; For example directly slope compensation signal VSLOPE is set to its amplitude (maximum), also or with certain slope slope compensation signal VSLOPE is increased gradually.In one embodiment, if load detecting unit 206 detects the instantaneous decline of load current, slope compensation unit 205 reduces the slope of slope compensation signal VSLOPE.In yet another embodiment, if load detecting unit 206 detects the instantaneous decline of load current, slope compensation unit 205 is reseted slope compensation signal VSLOPE and the slope of slope compensation signal VSLOPE is reduced.
In another embodiment, switch converters 200 can also comprise feedback circuit 207.Feedback circuit 207 has input and output, wherein input be coupled to switching circuit 204 output to receive output voltage VO UT, output is coupled to comparing unit 202 so that the feedback signal FB that represents output voltage VO UT to be provided.Comparing unit 202 produces comparison signal SET based on slope compensation signal VSLOPE, reference signal VREF and feedback signal FB.In one embodiment, feedback circuit 207 comprises resitstance voltage divider.
Fig. 3 is the circuit theory diagrams according to the switch converters 300 of the utility model one embodiment.The structural similarity of the structure of switch converters 300 and switch converters shown in Figure 2 200.Wherein switching circuit 304 adopts the synchronous buck transformation topology, comprises switching tube S1, S2, inductor L and output capacitor COUT.Switching circuit 304 converts input voltage VIN into output voltage VO UT through conducting and the shutoff of switching tube S1 and S2.Switching tube S1 has first end, second end and control end, and wherein first termination is received input voltage VIN.Switching tube S2 has first end, second end and control end, and wherein first end is coupled to second end of switching tube S1, the second end ground connection.Inductor L has first end and second end, and wherein first end is coupled to second end of switching tube S1 and first end of switching tube S2.Output capacitor COUT is coupled between second end and ground of inductor L.The voltage at output capacitor COUT two ends is output voltage VO UT.In another embodiment, switching tube S2 can be replaced by diode.
Comparing unit 302 comprises comparator C OM1.Comparator C OM1 has in-phase input end, inverting input and output; Wherein in-phase input end receives the poor of reference signal VREF and slope compensation signal VSLOPE; Inverting input is coupled to the output of switching circuit 304 to receive output voltage VO UT, and output provides comparison signal SET.In one embodiment, slope compensation signal VSLOPE also can be applied to output voltage VO UT, rather than is deducted from reference signal VREF.
ON time control unit 301 produces ON time control signal COT, with the conducting duration of control switch pipe S1.In one embodiment, the conducting duration of switching tube S1 is set to steady state value, or with input voltage VIN and/or the relevant variable value of output voltage VO UT.Logical block 303 is coupled to ON time control unit 301 and comparing unit 302, produces control signal CTRL according to ON time control signal COT and comparison signal SET.
In one embodiment, switch converters 300 also comprises drive circuit 308.Drive circuit 308 is coupled to logical block 303 with reception control signal CTRL, and produces the control end of drive signal to switching tube S1, S2, with conducting and the shutoff of driving switch pipe S1 and S2.
In some application scenario, the equivalent series resistance of output capacitor COUT may be introduced certain dc error between output voltage VO UT and reference signal VREF.In order to address this problem, in one embodiment, switch converters 300 shown in Figure 3 also comprises the error compensation link.In one embodiment, as shown in Figure 3, the error compensation link comprises pi element 309 and adder.Pi element 309 has first input end, second input and output, and wherein first input end receives reference signal VREF, and second input is coupled to the output of switching circuit 304 to receive output voltage VO UT.Pi element 309 produces proportional integral signal VPI based on reference signal VREF and output voltage VO UT at its output.Adder has first input end, second input and output; Wherein first input end receives reference signal VREF; Second input is coupled to the output of pi element 309 to receive proportional integral signal VPI, and output is coupled to comparing unit 302 so that reference signal VREFX to be provided.In one embodiment, pi element 309 comprises operational amplifier.In another embodiment, the error compensation link also can only comprise adder, with reference signal VREF and preset offset signal VOFFSET addition, and with both signal VREFX provides to comparing unit 302 with being worth as a reference.
In one embodiment, for fear of noise jamming etc. unit 302 is relatively impacted, cause switching tube S1 just to be turned off, be switched on again at once, control circuit also comprises minimum turn-off time quantum 310.This minimum turn-off time quantum 310 is at minimum turn-off duration TOFF MINInterior comparison signal SET shielding with comparing unit 302 outputs.For specification for simplicity, at this minimum turn-off time quantum 310 is repeated no more.
Fig. 4 is switch converters shown in Figure 3 300 oscillogram in normal operation according to the utility model one embodiment.When control signal CTRL was high level, switching tube S1 conducting and switching tube S2 turn-offed, and the electric current I L that flows through inductance L increases gradually.When the conducting duration of switching tube S1 reached the set time threshold TTH of ON time control unit 301, control signal CTRL became low level, and switching tube S1 is turned off, and switching tube S2 is switched on, and the electric current I L that flows through inductance L reduces gradually.As output voltage VO UT during less than the difference of reference signal VREFX and slope compensation signal VSLOPE, control signal CTRL becomes high level, and switching tube S1 is switched on and switching tube S2 is turned off.Above process constantly repeats.
In the embodiment shown in fig. 4, slope compensation signal VSLOPE is in switching tube S1 conducting and switching tube S2 equals amplitude VRAMP when turn-offing, switching tube S1 turn-off and during switching tube S2 conducting the slope descend.Slope compensation signal VSLOPE also can have other the form of expression, and for example slope compensation signal VSLOPE keeps the duration of amplitude VRAMP can be longer than time threshold TTH, for example equals time threshold TTH and minimum turn-off duration TOFF MINSum.Slope compensation signal VSLOPE also with the triangular signal of inductive current IL homophase, in switching tube S1 conducting and switching tube S2 rises on the slope when turn-offing, turn-off and switching tube S2 conducting descends on the slope constantly at switching tube S1.
In the embodiment of following described Fig. 5 to Fig. 7, slope compensation signal VSLOPE is a sawtooth signal, when switching tube S1 becomes conducting by shutoff, rapidly increases to amplitude, switching tube S1 turn-off and during switching tube S2 conducting the slope descend.But it will be understood by those skilled in the art that the slope compensation signal VSLOPE with other forms of expression is applicable to the utility model too.
Fig. 5 is the existing oscillogram of switch converters when the instantaneous decline of load current.In existing switch converters, slope compensation signal VSLOPE can not change with load condition.At t1 constantly, the instantaneous decline of load current, output voltage VO UT increases.If the rate of rise of output voltage VO UT is less than the descending slope of slope compensation signal VSLOPE; Then constantly at t2; Output voltage VO UT will be less than the difference VREFX-VSLOPE of reference signal and slope compensation signal; This can cause logical block to produce a conducting pulse before at the peak value that output voltage VO UT reaches its overshoot, thereby further increases the overshoot on the output voltage VO UT.
Fig. 6 is that wherein dotted portion is the oscillogram of existing switch converters shown in Figure 5 according to the switch converters shown in Figure 3 300 of the utility model one embodiment oscillogram when the instantaneous decline of load current.Shown in solid line part among Fig. 6, at t1 constantly, the instantaneous decline of load current, output voltage VO UT increases.At t3 constantly; Load detecting unit 306 detects the instantaneous decline of load current; Slope compensation signal VSLOPE is reseted in slope compensation unit 305; For example directly slope compensation signal VSLOPE is set to its amplitude VRAMP, thereby the difference VREFX-VSLOPE of reference signal and slope compensation signal reaches its minimum value, VREFX-VRAMP.In one embodiment, slope compensation signal VSLOPE begins to descend with preset slope in t4 moment side, till reaching its minimum value after one section time-delay.At t5 constantly, output voltage VO UT is less than the difference VREFX-VSLOPE of reference signal and slope compensation signal, and switching tube S1 is switched on and switching tube S2 is turned off.
Because when slope compensation unit 305 detects the instantaneous decline of load current in load detecting unit 306; VSLOPE resets with slope compensation signal; Avoided logical block 303 to produce the conducting pulse before at the peak value that output voltage VO UT reaches its overshoot; Thereby reduced the overshoot on the output voltage VO UT, improved the transient response of switch converters.
Fig. 7 is that wherein dotted portion is the oscillogram of existing switch converters shown in Figure 5 according to the switch converters shown in Figure 3 300 of another embodiment of the utility model oscillogram when the instantaneous decline of load current.Shown in solid line part among Fig. 7, at t1 constantly, the instantaneous decline of load current, output voltage VO UT increases.At t3 constantly, load detecting unit 306 detects the instantaneous decline of load current, and slope compensation unit 305 reduces the descending slope of slope compensation signal VSLOPE, thereby the rate of rise of the difference VREFX-VSLOPE of reference signal and slope compensation signal also reduces.Slope compensation signal VSLOPE descends with the slope after being reduced the back at t3 constantly, till reaching its minimum value.At t5 constantly; Output voltage VO UT is less than the difference VREFX-VSLOPE of reference signal and slope compensation signal; Switching tube S1 is switched on and switching tube S2 is turned off, and slope compensation signal VSLOPE is reseted, and slope compensation unit 305 returns to normal value with the descending slope of slope compensation signal VSLOPE.
Because when slope compensation unit 305 detects the instantaneous decline of load current in load detecting unit 306; The descending slope of slope compensation signal VSLOPE is reduced; Avoided logical block 303 to produce the conducting pulse before at the peak value that output voltage VO UT reaches its overshoot; Thereby reduced the overshoot on the output voltage VO UT, improved the transient response of switch converters.
Fig. 8 is that wherein dotted portion is the oscillogram of existing switch converters shown in Figure 5 according to the switch converters shown in Figure 3 300 of the another embodiment of the utility model oscillogram when the instantaneous decline of load current.Shown in solid line part among Fig. 8, at t1 constantly, the instantaneous decline of load current, output voltage VO UT increases.At t3 constantly, load detecting unit 306 detects the instantaneous decline of load current, and slope compensation unit 305 is reseted slope compensation signal VSLOPE and the slope of slope compensation signal VSLOPE is reduced.Slope compensation signal VSLOPE is set to its amplitude VRAMP, thereby the difference VREFX-VSLOPE of reference signal and slope compensation signal reaches its minimum value, VREFX-VRAMP.In one embodiment, slope compensation signal VSLOPE begins to descend with the slope after being reduced in t6 moment side after one section time-delay.At t7 constantly; Output voltage VO UT is less than the difference VREFX-VSLOPE of reference signal and slope compensation signal; Switching tube S1 is switched on and switching tube S2 is turned off, and slope compensation signal VSLOPE is reseted, and slope compensation unit 305 returns to normal value with the descending slope of slope compensation signal VSLOPE.
Because when slope compensation unit 305 detects the instantaneous decline of load current in load detecting unit 306; Slope compensation signal VSLOPE is reseted and its descending slope is reduced; Avoided logical block 303 to produce the conducting pulse before at the peak value that output voltage VO UT reaches its overshoot; Thereby reduced the overshoot on the output voltage VO UT, improved the transient response of switch converters.
Fig. 9 is the circuit theory diagrams according to the slope compensation unit of the utility model one embodiment.Digitial controller 921 produces digital reference signal DREFX and digital compensation signal DSLOPE.Digitial controller 921 is through digital operation, and DSLOPE deducts from digital reference signal DREFX with the digital compensation signal, and both difference is transferred to digital to analog converter 922.The analog signal of digital to analog converter 922 outputs is the difference VREFX-VSLOPE of reference signal and slope compensation signal.Digitial controller 921 is through regulating digital compensation signal DSLOPE, i.e. the slope of scalable slope compensation signal VSLOPE or slope compensation signal VSLOPE reseted.
Figure 10 is the circuit theory diagrams according to the slope compensation unit of another embodiment of the utility model.Digitial controller 1021 produces digital reference signal DREFX and digital compensation signal DSLOPE.Digital reference signal DREFX is transferred to digital to analog converter 1023, and the analog signal of digital to analog converter 1023 outputs is reference signal VREFX.Digital compensation signal DSLOPE is transferred to digital to analog converter 1024, and the analog signal of digital to analog converter 1024 outputs is slope compensation signal VSLOPE.Computing circuit 1025 deducts slope compensation signal VSLOPE from reference signal VREFX, and exports both difference VREFX-VSLOPE.Digitial controller 1021 is through regulating digital compensation signal DSLOPE, i.e. the slope of scalable slope compensation signal VSLOPE or slope compensation signal VSLOPE reseted.
Figure 11 is the circuit theory diagrams according to the slope compensation unit of the another embodiment of the utility model.Digitial controller 1121 produces digital reference signal DREFX, control signal CTRL1 and digital slope signal DSR1 and DSR2.Digital to analog converter 1123 is coupled to digitial controller 1121 to receive digital reference signal DREFX, and the analog signal of digital to analog converter 1023 outputs is reference signal VREFX.Digital to analog converter 1126 is coupled to digitial controller 1121 to receive digital slope signal DSR1, digital to analog converter 1126 output analog signal VSR1.Switching tube S3 has first end, second end and control end, and wherein first end is coupled to the output of digital to analog converter 1126, and second end is coupled to VCCS VCCS, and control end is coupled to digitial controller 1121 to receive control signal CTRL1.Capacitor C1 has first end and second end, wherein the second end ground connection.The voltage at capacitor C1 two ends is slope compensation signal VSLOPE.VCCS VCCS is coupled to first end and second end of capacitor C1.In switching tube S3 conduction period, VCCS VCCS charges to capacitor C1, and the charging current of its output and signal VSR1 are proportional.Discharge circuit 1127 also is coupled to first end of capacitor C1, comprises switch arrays and current mirroring circuit that switching tube and resistor are formed, and its connection is shown in figure 11.Discharge circuit 1127 is coupled to digitial controller 1121 to receive digital slope signal DSR2.The conducting and the shutoff of switching tube in the numeral slope signal DSR2 control switch array, thereby the discharging current of control capacitance device C1.Computing circuit 1125 deducts slope compensation signal VSLOPE from reference signal VREFX, and exports both difference VREFX-VSLOPE.
Digitial controller 1121 is through regulating digital slope signal DSR1 and DSR2, the rate of rise and the descending slope of scalable slope compensation signal VSLOPE.Those skilled in the art can confirm the number of switching tube and resistor in the switch arrays of Figure 11 according to actual conditions, and adopt the resistor of similar resistance or different resistances according to actual conditions.
Figure 12 is the circuit theory diagrams according to the slope compensation unit of the utility model one embodiment.Digitial controller 1221 produces digital current control signal DCS, control signal CTRL2 and CTRL3, digital reference signal DREFX and digital magnitude signal DRAMP.Digitial controller 1221 is through digital operation, and DRAMP deducts from digital reference signal DREFX with the digital magnitude signal, and both difference is provided to the input of digital to analog converter 1229.Numerical Controlled Current Source 1228 has first end, second end and control end, and wherein first end is coupled to supply power voltage VCC, and control end is coupled to digitial controller 1221 to receive digital current control signal DCS.Switching tube S4 has first end, second end and control end, and wherein first end is coupled to second end of Numerical Controlled Current Source 1228, and control end is coupled to digitial controller 1221 to receive control signal CTRL2.Switching tube S5 has first end, second end and control end, and wherein first end is coupled to second end of switching tube S4, and second end is coupled to the output of digital to analog converter 1229, and control end is coupled to digitial controller 1221 to receive control signal CTRL3.Capacitor C2 has first end and second end, and wherein first end is coupled to second end of switching tube S4 and first end of switching tube S5, and second end is coupled to second end of switching tube S5 and the output of digital to analog converter 1229.The voltage that capacitor C1 first end is provided is the poor of reference signal and slope compensation signal, VREFX-VSLOPE.In one embodiment, the slope compensation unit also comprises the output that is coupled in digital to analog converter 1229 and the buffer circuit BUF between capacitor C2 second end.Digitial controller 1221 is through changing digital current control signal DCS, the i.e. descending slope of scalable slope compensation signal VSLOPE.Digitial controller 1221 makes switching tube S5 conducting through regulating control signal CTRL3, can slope compensation signal VSLOPE be reseted.
In one embodiment; Switch converters adopts digital control approach, and load detecting unit as shown in Figure 3, pi element, ON time control unit, minimum turn-off time quantum and logical block can be realized by the digitial controller shown in Fig. 9 to 12.
Though described the utility model with reference to several exemplary embodiments, should be appreciated that used term is explanation and exemplary and nonrestrictive term.Because the utility model practical implementation and do not break away from the spirit or the essence of utility model in a variety of forms; So be to be understood that; The foregoing description is not limited to any aforesaid details; And should in enclose spirit that claim limited and scope, explain widely, therefore fall into whole variations and remodeling in claim or its equivalent scope and all should be the claim of enclosing and contain.

Claims (10)

1. control circuit that is used for switch converters, this switch converters comprises the switching circuit with at least one switching tube, it is characterized in that, this control circuit comprises:
The ON time control unit has output, produces the ON time control signal at output;
The slope compensation unit has output, produces slope compensation signal at output;
Comparing unit; Have first input end, second input, the 3rd input and output; Wherein first input end receives reference signal, and second input is coupled to the output voltage of the output of switching circuit with the receiving key circuit, and the 3rd input is coupled to the output of slope compensation unit to receive slope compensation signal; Comparing unit produces comparison signal based on reference signal, output voltage and slope compensation signal at output;
Logical block; Have first input end, second input and output; Wherein first input end be coupled to the ON time control unit output to receive the ON time control signal, second input is coupled to the output of comparing unit to receive comparison signal, logical block is according to ON time control signal and comparison signal; Produce control signal at output, with the conducting and the shutoff of at least one switching tube in the control switch circuit; And
The load detecting unit has output, detects load condition and produces detection signal at output; Wherein
The slope compensation unit also has input, and this input is coupled to the output of load detecting unit to receive detection signal, and the slope compensation unit is regulated slope compensation signal according to detection signal.
2. control circuit as claimed in claim 1 is characterized in that, wherein if the load detecting unit detects load current to descend, the slope compensation unit is reseted slope compensation signal and/or the slope of slope compensation signal is reduced.
3. control circuit as claimed in claim 1 is characterized in that, wherein the slope compensation unit comprises:
Controllable current source has first end, second end and control end, and wherein first end is coupled to supply power voltage;
The first transistor has first end, second end and control end, and wherein first end is coupled to second end of controllable current source;
Capacitor has first end and second end, and wherein first end is coupled to second end of the first transistor;
Transistor seconds has first end, second end and control end, and wherein first end is coupled to second end of the first transistor and first end of capacitor, and second end is coupled to second end of capacitor.
4. control circuit as claimed in claim 1; It is characterized in that; Wherein comparing unit comprises comparator, and this comparator has first input end, second input and output, and wherein first input end receives the poor of reference signal and slope compensation signal; The output that second input is coupled to switching circuit is to receive output voltage or to represent the feedback signal of output voltage, and output provides comparison signal.
5. control circuit as claimed in claim 1 is characterized in that, also comprises:
Pi element; Have first input end, second input and output; Wherein first input end receives reference signal; Second input is coupled to the output of switching circuit to receive output voltage, and pi element produces the proportional integral signal based on reference signal and output voltage at its output;
Adder; Have first input end, second input and output; Wherein first input end receives reference signal, and second input is coupled to the output of pi element to receive the proportional integral signal, and output is coupled to comparing unit so that reference signal and proportional integral signal sum to be provided.
6. control circuit as claimed in claim 1; It is characterized in that; Wherein the load detecting unit compares the switch periods under current switch periods and the stable state, descends if current switch periods than long certain proportion of switch periods under the stable state or numerical value, then is regarded as detecting load current.
7. control circuit as claimed in claim 1 is characterized in that, wherein the load detecting unit detects load current, and the preset value if load current descends then is regarded as detecting load current and descends.
8. control circuit as claimed in claim 1 is characterized in that, wherein the output voltage of load detecting unit sense switch circuit if output voltage rises to a preset value, then is regarded as detecting load current and descends.
9. a switch converters is characterized in that, comprising:
Switching circuit comprises at least one switching tube, and the conducting through this at least one switching tube converts input voltage into output voltage with turn-offing; And
Like each described control circuit in the claim 1 to 8.
10. switch converters as claimed in claim 9 is characterized in that, wherein said switching circuit comprises:
First switching tube has first end, second end and control end, and wherein first termination is received input voltage, and control end is coupled to logical block to receive control signal;
The second switch pipe has first end, second end and control end, and wherein first end is coupled to second end of first switching tube, the second end ground connection, and control end is coupled to logical block to receive control signal;
Inductor has first end and second end, and wherein first end is coupled to second end of first switching tube and first end of second switch pipe; And
Output capacitor is coupled between second end and ground of inductor.
CN2012201204163U 2012-03-27 2012-03-27 Switch converter and control circuit thereof Expired - Fee Related CN202475254U (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103269548A (en) * 2013-05-29 2013-08-28 成都芯源***有限公司 LED drive circuit system, controller and control method
CN109088449A (en) * 2018-06-28 2018-12-25 杭州茂力半导体技术有限公司 Battery charger and its control circuit and control method
CN111224645A (en) * 2018-11-26 2020-06-02 力智电子股份有限公司 DC-DC conversion circuit and time signal generator thereof
CN112398335A (en) * 2019-08-14 2021-02-23 圣邦微电子(北京)股份有限公司 Control circuit and control method of switching regulator and switching regulator
CN112653333A (en) * 2020-12-18 2021-04-13 电子科技大学 Digital-analog hybrid control circuit and control method of DC-DC converter
CN114189152A (en) * 2021-08-16 2022-03-15 杰华特微电子股份有限公司 Compensation control circuit and control method of switch type regulator and switch type regulator
CN115309222A (en) * 2022-08-26 2022-11-08 中国计量大学 Precise current source device based on digital regulation and control slope compensation

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103269548B (en) * 2013-05-29 2015-07-08 成都芯源***有限公司 LED drive circuit system, controller and control method
CN103269548A (en) * 2013-05-29 2013-08-28 成都芯源***有限公司 LED drive circuit system, controller and control method
CN109088449A (en) * 2018-06-28 2018-12-25 杭州茂力半导体技术有限公司 Battery charger and its control circuit and control method
CN109088449B (en) * 2018-06-28 2020-10-13 杭州茂力半导体技术有限公司 Battery charging circuit and control method thereof
CN111224645B (en) * 2018-11-26 2023-10-20 力智电子股份有限公司 DC-DC conversion circuit and time signal generator thereof
CN111224645A (en) * 2018-11-26 2020-06-02 力智电子股份有限公司 DC-DC conversion circuit and time signal generator thereof
CN112398335A (en) * 2019-08-14 2021-02-23 圣邦微电子(北京)股份有限公司 Control circuit and control method of switching regulator and switching regulator
CN112653333A (en) * 2020-12-18 2021-04-13 电子科技大学 Digital-analog hybrid control circuit and control method of DC-DC converter
CN112653333B (en) * 2020-12-18 2021-10-08 电子科技大学 Digital-analog hybrid control circuit and control method of DC-DC converter
CN114189152A (en) * 2021-08-16 2022-03-15 杰华特微电子股份有限公司 Compensation control circuit and control method of switch type regulator and switch type regulator
CN114189152B (en) * 2021-08-16 2024-01-23 杰华特微电子股份有限公司 Compensation control circuit and control method of switch type regulator and switch type regulator
CN115309222A (en) * 2022-08-26 2022-11-08 中国计量大学 Precise current source device based on digital regulation and control slope compensation
CN115309222B (en) * 2022-08-26 2024-01-16 中国计量大学 Precision current source device based on digital regulation and control slope compensation

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