CN204131395U - Control circuit for switching converter - Google Patents
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- CN204131395U CN204131395U CN201420585345.3U CN201420585345U CN204131395U CN 204131395 U CN204131395 U CN 204131395U CN 201420585345 U CN201420585345 U CN 201420585345U CN 204131395 U CN204131395 U CN 204131395U
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Abstract
A control circuit for a switching converter having a high-side switch and a low-side switch coupled in series is disclosed, the control circuit including an on signal generating circuit, an off signal generating circuit, a first comparing circuit, a second comparing circuit, and a logic circuit. The control circuit can enable the peak current of the high-side switch to be larger than the zero-crossing protection threshold of the low-side switch, so that false triggering or non-triggering of the zero-crossing protection function of the low-side switch is avoided.
Description
Technical field
Embodiment of the present utility model relates to electronic circuit, but more specifically not exclusively relates to a kind of control circuit for dc-dc converter.
Background technology
Dc-dc converter is generally configured to provide adjusted output voltage or electric current (" load voltage " or " load current ") based at some unadjusted input source voltages to load.Such as in the application of many automobiles (wherein battery provides the power source with approximate 12 volts of unadjusted voltages), dc-dc converter can be used for receiving unadjusted 12 volts of DC as source voltage provides adjusted DC output voltage or electric current to drive the various electronic circuits in vehicle (instrument, annex, engine control, lighting apparatus, radio/stereo etc.).DC output voltage can be lower, higher or identical than the source voltage from battery.Again such as in some illumination application, dc-dc converter can be used for receiving unadjusted 12 volts of DC as source voltage provides adjusted DC output current with driving LED.
Fig. 1 illustrates the circuit diagram of the dc-dc converter 10 of a employing constant on-time control structure.Dc-dc converter 10 comprises control circuit 100 and switching circuit 110.Switching circuit 110 have employed synchronous buck transformation topology, comprises high-side switch M1, low side switch M2, inductor L and output capacitor C.Switching circuit 110 passes through conducting and the shutoff of switching tube M1 and M2, and input voltage VIN is converted to output voltage VO UT.The first end of high-side switch M1 receives input voltage VIN, and the second end is electrically coupled to the first end of low side switch M2.Second end of low side switch M2 is by earth terminal ground connection.The first end of inductor L is electrically coupled to the link (switch terminals) of switch M1 and M2, and output capacitor C electric coupling is between second end and ground of inductor L.The voltage at output capacitor C two ends is output voltage VO UT.
Control circuit 100 comprises Continuity signal and produces circuit 101, cut-off signals generation circuit 102, logical circuit 103.Continuity signal produces circuit 101, and have first input end, the second input and output, the comparative result based on reference signal VREF and output voltage VO UT provides Continuity signal SETON at output; Cut-off signals produces circuit 102, cut-off signals SETOFF is provided, cut-off signals produces circuit 102 and starts timing when high-side switch M1 conducting, timing terminates (this period is called setting-up time TS or ON time) moment, and it is the second state (such as high level) that cut-off signals SETOFF is overturn by the first state (such as low level).Logical circuit 103, has first input end, the second input and output, provides control signal CTRL to control conducting and the shutoff of high-side switch M1 and low side switch M2 based on Continuity signal SETON, cut-off signals SETOFF at output.Usually, when Continuity signal SETON is enable, high-side switch M1 switches to conducting by shutoff; When cut-off signals SETOFF is enable (be second state by the first state turnover), high-side switch M1 switches to shutoff by conducting.
Under underloading condition, inductive current IL may be reduced to zero and notably be less than zero, and namely electric current can flow into earth potential from output capacitance C through inductance L and low side switch M2, enters thus affects the efficiency of dc-dc converter 10.For this reason, control circuit 100 generally includes Zero-cross comparator circuit 104, the electric current (i.e. inductive current IL) of low side switch M2 is compared with current threshold IZE, close low side switch M2 when the electric current of low side switch M2 is reduced to current threshold IZE, to avoid, low side switch M2 ER effect is negative or negative current is excessive.When current threshold IZE value is too small, due to the delay of current over-zero comparison circuit 104 or low side switch M2 curent change too fast, when low side switch M2 turns off, low side switch M2 electric current may be reduced to the negative value far below zero; If current threshold IZE arranges excessive; Zero-cross comparator circuit 104 false triggering may be caused or zero passage protection cannot be triggered; such as current threshold IZE is set to 200mA; under some load; the peak value (i.e. the current peak of high-side switch M1) of inductive current IL can not reach 200mA; thus after high-side switch M1 closes; Zero-cross comparator circuit 104 can directly be closed low side switch M2 thus cause false triggering, or keeps low side switch M2 conducting always to such an extent as to cannot obtain the function of current over-zero protection.
For this reason, how to obtain more optimal there is zero passage defencive function control circuit and control method be the difficult problem that those skilled in the art face.
Utility model content
For solving the problem, the utility model provides a kind of control circuit for dc-dc converter.
According to an aspect of the present utility model, the utility model provides a kind of control circuit for dc-dc converter, described dc-dc converter has high-side switch and the low side switch of coupled in series, 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, provides cut-off signals, and described cut-off signals is the second state by the first state turnover at the end of setting-up time, first comparison circuit, the comparative result based on high-side switch electric current and first threshold provides the first comparison signal, second comparison circuit, the comparative result based on low side switch electric current and Second Threshold provides the second comparison signal, and wherein Second Threshold is less than first threshold, logical circuit, there is first input end, second input, 3rd input, four-input terminal, first output and the second output, based on described Continuity signal, described cut-off signals, described first comparison signal and described second comparison signal provide the first switching signal to control conducting and the shutoff of described high-side switch at its first output, there is provided second switch signal to control conducting and the shutoff of described low side switch at its second output, wherein, at the end of described setting-up time, if described high-side switch electric current is less than described first threshold, described high-side switch by maintenance conducting until described high-side switch electric current is equal to, or greater than described first threshold.
According to an embodiment of the present utility model, at the end of described setting-up time, if described high-side switch electric current is less than described first threshold, described first comparison signal makes described high-side switch keep conducting by the described cut-off signals of shielding or described first switching signal.
According to an embodiment of the present utility model, when described cut-off signals has the first state, described high-side switch keeps conducting; When described cut-off signals has the second state, when described high-side switch electric current increases to described first threshold, described first switching signal turns off described high-side switch.
According to an embodiment of the present utility model, in described setting-up time, if described high-side switch electric current is greater than or equal to described first threshold, described first switching signal turns off described high-side switch at the end of described setting-up time.
According to an embodiment of the present utility model, when described high-side switch electric current is less than described first threshold, described first comparison signal has the first state; When described high-side switch electric current is greater than described first threshold, described first comparison signal has the second state; In described setting-up time, if described first comparison signal has the second state, when described cut-off signals upset is the second state, described first switching signal turns off described high-side switch.
According to an embodiment of the present utility model, described high-side switch has first end, the second end and control end, its first end receives input voltage, its control end receives described first switching signal: described low side switch has first end, the second end and control end, its first end is coupled to the second end of described high-side switch, its second end is coupled to earth terminal, and its control end is coupled to described second switch signal; Described dc-dc converter also comprises: inductor, has first end and the second end, and wherein first end is electrically connected to the second end of described high-side switch, and its second end provides output voltage; And output capacitance, have first end and the second end, wherein first end is coupled to the second end of described inductance, and its second end is coupled to earth terminal.
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 first input end and second input of described turning circuit respectively; And first voltage comparator, comprise first input end, the second input and output, its first input end is coupled to the output of described first amplifier, its second input is coupled to the second input of described 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 cut-off signals produces circuit and comprises timing circuit, when the time zero of described setting-up time is described high-side switch conducting.
According to an embodiment of the present utility model, described cut-off signals produces circuit and comprises, and the first electric capacity, has first end and the second end, and its second end is coupled to earth terminal; First switch, has first end, the second end and control end, and its first end and the second end are coupled to the two ends of described first electric capacity respectively, and its control end is coupled to described first switching signal; First current source, have first end, the second end, its first end is coupled to the input voltage of described dc-dc converter, and its second end is coupled to the first end of described first electric capacity; Second voltage comparator, has first input end, the second input and output, and its first input end is coupled to the first end of described first electric capacity, and its second termination receives voltage compare threshold value, and output provides described cut-off signals.
According to an embodiment of the present utility model, the electric current of described first current source is directly proportional or linear relationship to the input and output voltage ratio of described dc-dc converter.
According to an embodiment of the present utility model, also comprise the threshold adjustment circuit adjusting described first threshold, after described high-side switch ON time is more than the first ON time, described threshold value arranges circuit and reduces described first threshold, and wherein said first ON time is more than or equal to zero.
According to an embodiment of the present utility model, also comprise maximum ON time and circuit is set, when the ON time of described high-side switch is more than the second ON time, high-side switch described in described maximum ON time circuit shut-down.
According to an embodiment of the present utility model, described logical circuit comprises the first logical circuit, and have first input end, the second input and output, its first input end receives described cut-off signals, and its second input receives described first comparison signal; Trigger logic, there is first input end, the second input, the first output and the second output, wherein first input end is coupled to the output of described first logical circuit, its second input receives described Continuity signal, its the first output end provides described first drive singal, and its second output provides driving reverse signal; And second logical circuit, have first input end, the second input and output, its first input end receives described driving reverse signal, and its second input receives described second comparison signal, and its output provides described second drive singal.
According to an embodiment of the present utility model, described first logical circuit is and logical circuit, and described trigger logic is RS trigger logic, and described second logical circuit is and logical circuit.
The control circuit for dc-dc converter that the utility model provides can make the peak current of high-side switch M1 be not less than first threshold IAAM; after low side switch M2 conducting; the electric current I M2 of low side switch reduces from the electric current higher than Second Threshold IZE; until arrive the minimum current I ZE of setting, thus avoid that inductive current is too small to be caused the false triggering of low side switch zero passage defencive function or do not trigger.
Accompanying drawing explanation
The utility model illustrates by example and with reference to the mode of accompanying drawing, wherein:
Fig. 1 illustrates the circuit diagram of a existing dc-dc converter 10;
Fig. 2 illustrates the circuit diagram of a dc-dc converter 20 according to an embodiment of the present utility model;
Fig. 3 illustrates the waveform 300 in dc-dc converter 20 running;
Fig. 4 illustrates the waveform 400 in dc-dc converter 20 running; And
Fig. 5 illustrates the circuit diagram of a dc-dc converter 50 according to an embodiment of the present utility model.
Embodiment
Specific embodiment hereinafter described represents exemplary embodiment of the present utility model, and be only in essence example illustrate and unrestricted.In the description, mention that " embodiment " or " embodiment " mean to be included at least one embodiment of the present utility model in conjunction with the special characteristic described by this embodiment, structure or characteristic.Term " in one embodiment " in the description each position occurs all not relating to identical embodiment, neither mutually get rid of other embodiments or various embodiments.All features disclosed 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 embodiment of the present utility model below with reference to the accompanying drawings in detail.The Reference numeral running through institute's drawings attached identical represents identical parts or feature.
Fig. 2 illustrates the circuit diagram of a dc-dc converter 20 according to the utility model one enforcement.Dc-dc converter 20 comprises switching circuit 110 and control circuit 200.In other embodiments, switching circuit 110 can also have other topological structures, such as Boost type boost configuration and the topological structure such as normal shock or flyback.In embodiment 20, high-side switch M1 is a nmos pass transistor, can also use PMOS transistor or JFET or igbt transistor in other embodiments.
Control circuit 200 comprises Continuity signal and produces circuit 201, cut-off signals generation circuit 202, first comparison circuit 203, second comparison circuit 204 and logical circuit 205.Continuity signal produces circuit 201, has first input end, the second input and output, provides Continuity signal SETON based on reference signal VREF and feedback signal VFB comparative result at output.In the embodiment shown in Figure 2, resistance R1 and R2 forms sample circuit 206 provides feedback signal VFB with sampling and outputting voltage VOUT.In one embodiment, Continuity signal produces circuit 201 and can also provide Continuity signal SETON based on the comparative result of reference signal VREF and the signal characterizing load current IOUT at output.In one embodiment, Continuity signal produces circuit 201 and comprises the first voltage comparator CMP1, first voltage comparator CMP1 has first input end, the second input and output, is configured to the first input end of described Continuity signal generation circuit 201, the second input and output respectively.
Cut-off signals produces circuit 202, provides cut-off signals SETOFF, and cut-off signals SETOFF is the second state by the first state turnover after setting-up time TS terminates.Setting-up time TS can be set time section, can also according to input voltage VIN, output voltage VO UT, load current IOUT and change.In one embodiment, setting-up time TS can be determined by timing circuit, timing circuit is configured to start timing when the first switching signal DL1 conducting high-side switch M1, and after timing terminates (setting-up time TS terminates), cut-off signals SETOFF is the second state by the first state turnover.In other embodiments, setting-up time TS can by the Determines of coherent signal, the such as size of inductive current IL, the size etc. of load current.
First comparison circuit 203, based on the comparative result of high-side switch electric current I M1 and first threshold IAAM, provides the first comparison signal CTI1.In certain embodiments, the electric current I M1 of high-side switch M1 can be detected by current detection circuit, and electric current and first threshold IAAM are compared.
Second comparison circuit 204, based on the comparative result of low side switch electric current I M2 and Second Threshold IZE, provide the second comparison signal CTI2, wherein Second Threshold IZE is less than first threshold IAAM.In certain embodiments, the electric current I M2 of low side switch M2 can be detected by current detection circuit, and electric current and Second Threshold IZE are compared.
Logical circuit 205, there is first input end, the second input, the 3rd input, four-input terminal, the first output and the second output, there is provided the first switching signal DL1 to control conducting and the shutoff of high-side switch M1 based on Continuity signal SETON, cut-off signals SETOFF, the first comparison signal CTI1 and the second comparison signal CTI2 at the first output, provide second switch signal DL2 to control conducting and the shutoff of low side switch M2 at the second output.At the end of setting-up time TS, if high-side switch electric current I M2 is less than first threshold IAAM, high-side switch M2 by maintenance conducting until high-side switch electric current I M1 is equal to, or greater than first threshold IAAM.High-side switch M1 closes and has no progeny; low side switch M2 conducting; the electric current I M2 of low side switch reduces from the electric current higher than Second Threshold IZE, until be reduced to the Second Threshold IZE of setting, thus avoids that inductive current is too small to be caused the false triggering of low side switch zero passage defencive function or do not trigger.
According to the utility model embodiment, logical circuit 205 comprises, and the first logical circuit 2051 has first input end, the second input and output, and its first input end receives cut-off signals SETOFF, and its second input receives the first comparison signal CTI1.First logical circuit 2051 can adopt and realize with logical circuit (with door), in other embodiments, can also select or the logical circuit such as door, XOR gate according to the logic state of cut-off signals SETOFF and the first comparison signal CTI1.Trigger Logic 2052, there is first input end (R end), the second input (S end), the first output (Q end) and the second output (QN end), wherein R end is coupled to the output with the first logical circuit 2015, S termination receives Continuity signal SETON, Q end provides the first drive singal DL1 to drive high-side switch M1, and QN end provides and drives reverse signal NDL1.Trigger logic 2052 can realize by rest-set flip-flop, in other embodiments, d type flip flop, T trigger can also be selected to realize according to the logic state of Continuity signal SETON and the first logical circuit 2051 output signal.Second logical circuit 2053, has first input end, the second input and output, and its first input end receives reverse signal NDL1, and its second input receives the second comparison signal CTI2, and output provides the second drive singal DL2 to drive low side switch M2.Second logical circuit 2053 can adopt and realize with logical circuit (with door), in other embodiments, can also select or the logical circuit such as door, XOR gate according to the logic state of reverse signal NDL1 and the second comparison signal CTI2.
Fig. 3 illustrates according to the waveform 300 in dc-dc converter 20 running of the utility model embodiment.At a time, when feedback voltage V FB is lower than reference voltage VREF, the Continuity signal SETON that Continuity signal produces the output of circuit 201 is high level by low transition, and the first switching signal DL1 that logical circuit 205 exports is that high level is to open high-side switch M1 by low transition.After high-side switch M1 opens, cut-off signals produces circuit 202 and starts timing, and high-side switch electric current I M1 continues to increase.After setting-up time TS, the cut-off signals SETOFF that cut-off signals produces the output of circuit 202 is converted to (high level) second state by the first state (low level).But now, because high-side switch electric current I M1 is less than first threshold IAAM, the first comparison signal CTI1 that first comparison circuit 203 exports is low level, namely the first comparison signal CTI1 shields cut-off signals SETOFF, first logical circuit 2051 will continue output low level, high-side switch M1 keeps conducting, and the electric current I M1 of high-side switch continues to increase.When the electric current I M1 electric current of high-side switch increases to first threshold IAAM, the first comparison signal CTI1 that first comparison circuit 203 exports switches to high level by low level, because the cut-off signals SETOFF of another input reception of the first logical circuit 2051 before this switches to high level, logical circuit 2051 will switch to high level along with the first comparison signal CTI1.The first drive singal DL1 that Trigger Logic 2052 exports will switch to low level by high level, and high-side switch M1 will turn off, and low side switch M2 is by conducting.Then, inductive current IL (the electric current I M2 of low side switch M2) reduces starting, when being decreased to Second Threshold IZE, the second comparison signal CTI2 that second comparison circuit 204 exports switches to low level by high level, after the second logical circuit 2053, second drive singal DL2 switches to low level by high level, and low side switch M2 turns off.In Fig. 3, the dotted line of the first drive singal DL1 represents when not using the first comparison circuit 203, and the first drive singal DL1 will turn off high-side switch M1 at cut-off signals SETOFF by during low transition high level.In addition, low side switch M2 closes and has no progeny, and electric current I M2 and the inductive current IL of low side switch are no longer equal, and for this reason, low side switch M2 represented by dashed line closes the inductive current IL had no progeny.
In the embodiment shown in Figure 2, the first comparison signal CTI1 makes high-side switch M1 keep conducting by shielding cut-off signals SETOFF.In other embodiments, high-side switch M1 can also be made to keep conducting by shielding first switching signal DL1.
According to the utility model embodiment, in setting-up time TS, if high-side switch electric current I M1 is greater than or equal to first threshold IAAM, the first switching signal DL1 turns off high-side switch M1 at the end of ON time TON.Fig. 4 illustrates according to the waveform 400 in dc-dc converter 20 running of the utility model embodiment.At a time, when feedback voltage V FB is lower than reference voltage VREF, the Continuity signal SETON that Continuity signal produces the output of circuit 201 is high level by low transition, and the first switching signal DL1 that logical circuit 205 exports is that high level is to open high-side switch M1 by low transition.After high-side switch M1 conducting, cut-off signals produces circuit 202 and also starts timing, and the electric current I M1 of high-side switch continues to increase.After high-side switch M1 conducting a period of time, high-side switch electric current I M1 exceedes first threshold IAAM, and the first comparison signal CTI1 that the first comparison circuit 203 exports switches to high level by low level.After ON time TON, the cut-off signals SETOFF that cut-off signals produces the output of circuit 202 is high level by low transition, because the first comparison signal CTI1 of another input reception of logical circuit 2051 before this switches to high level, logical circuit 2051 will switch to high level along with cut-off signals SETOFF.The first drive singal DL1 that Trigger Logic 2052 exports will switch to low level by high level, and high-side switch M1 will turn off, and low side switch M2 is by conducting.Then, inductive current (the electric current I M2 of low side switch M2) reduces starting, when being decreased to Second Threshold IZE, the second comparison signal CTI2 that second comparison circuit 204 exports switches to low level by high level, through with logical circuit 2053 after, second drive singal DL2 switches to low level by high level, and low side switch M2 turns off.
Fig. 5 illustrates the circuit diagram of a dc-dc converter 50 according to the utility model one enforcement.Dc-dc converter 50 comprises switching circuit 110 and control circuit 500.Compared with the control circuit 200 shown in Fig. 2, control circuit 500 adopts Continuity signal to produce, and circuit 501 substituted for Continuity signal generation circuit 201, cut-off signals produces circuit 502 and substituted for cut-off signals generation circuit 202, and comprises current analog circuit 503 and threshold adjustment circuit 504 further.
Compared with the control circuit 201 shown in Fig. 2, Continuity signal produces circuit 501 and comprises the first amplifier EA1 further.First amplifier EA1, comprise first input end, the second input and output, its first input end is configured to Continuity signal and produces the first input end of circuit 501 to receive reference signal VREF, its second input is configured to Continuity signal and produces the second input of circuit 501 with receiving feedback signals VFB, and its output provides error amplification signal VEA.The first input end of the first comparator CMP1 is coupled to the output of the first amplifier EA1, its second input receiving feedback signals VFB, and its output is configured to the output that Continuity signal produces circuit 501.First amplifier EA1 can improve the load regulation of dc-dc converter 50 and output voltage VO UT (or electric current) precision well.
Cut-off signals produces circuit 502 and comprises the first switch S 1, first electric capacity C1, the first current source I1 and the second voltage comparator CMP2.First electric capacity C1, has first end and the second end, and its second end is coupled to earth potential GND.First switch S 1, has first end, the second end and control end, and its first end and the second end are coupled to the two ends of the first electric capacity C1 respectively, and its control end is coupled to the first drive singal DL1.First current source I1, have first end, the second end, its first end is coupled to input voltage VIN, and its second end is coupled to the first electric capacity C1 first end.Second voltage comparator CMP2, has first input end, the second input and output, and its first input end is coupled to the first end of the first electric capacity C1, and its second termination receives voltage threshold signals VTH, and output provides cut-off signals SETOFF.
According to the utility model embodiment, the high-side switch M1 conducting when the first drive singal DL1 is converted to high level, the first switch S 1 disconnects, and the first current source I1 starts to charge to the first electric capacity C1.When the voltage of the first electric capacity C1 is increased to voltage threshold signals VTH, the second voltage comparator CMP2 output end voltage (i.e. cut-off signals SETOFF) switches to high level by low level.Assuming that the first current source I1 charging current is ICH, then have
When heavier loads, setting-up time TS is the ON time of high-side switch M1.According to the operation principle of reduction voltage circuit, can know, under current continuity mode of operation, switch periods TSW can be expressed as,
Can be obtained by formula (1), (2),
If namely ICH can be expressed as
Wherein k is coefficient, if that is, the electric current of charging the first current source can be proportional to input and output voltage ratio (VIN/VOUT), then in ccm mode, the switch periods TSW of dc-dc converter 20 and 50 is by substantially constant.In one embodiment, the electric current of current source I1 and input and output voltage ratio linear or be directly proportional.
Current analog circuit 503, voltage (difference of first end voltage or first end and the second terminal voltage) based on low side switch M2 is simulated, the change of the electric current I M2 of virtual or matching low side switch M2, to produce the voltage signal or current analog signal DIM2 (assuming that the ratio of IM2 and DIM2 is for 1:1) that are directly proportional to electric current I M1.Second comparison circuit 204, compares current analog signal DIM2 Second Threshold IZE, provides the second comparison signal CTI2.In like manner, current analog circuit 503 can also be used for simulating high-side switch electric current I M1 and be supplied to the first comparison circuit 203.For this reason; " comparative result based on high side/low side switch electric current and the first/bis-threshold value " is not meant that and necessarily need high side/low side switch of sampling; do not mean that and the current signal of high side/low side switch directly directly must be compared with the first/bis-threshold value yet; the voltage of high side/low side switch electric current or current signal and respective threshold can be characterized compare, be no more than protection range of the present utility model equally.
Under some application, for preventing high-side switch M1 constant conduction overlong time from causing switching frequency to enter audio frequency, even damage the situations such as device,
The threshold value that control circuit 500 comprises adjusting first threshold IAAM alternatively arranges circuit 504.Threshold value arranges circuit 504 and has output and output.In one embodiment, as shown in Figure 5, threshold value arranges circuit 504 input and is coupled to the first switching signal DL1, the ON time of high-side switch M1 is monitored by monitoring the first switching signal DL1, when the ON time of high-side switch M1 is more than the first ON time TON1, threshold value arranges circuit 504 and reduces first threshold IAAM.First threshold IAAM can little by little reduce continuously, also can the stepped reduction with variable or fixing step-length, such as, reduce 50 milliamperes every 10 microseconds.In another embodiment, threshold value arranges circuit 504 input can also be coupled to cut-off signals SETOFF, start to reduce first threshold IAAM when being the second state from cut-off signals SETOFF upset, or a time period after cut-off signals SETOFF upset is the second state starts to reduce first threshold IAAM.Those skilled in the art according to demand, can reasonably arrange the first ON time TON1, can be set to zero, also can be set to hundreds of nanosecond, several microseconds etc.Preferably, the first ON time TON1 is greater than setting-up time TS.For the situation that first threshold IAAM is variable, Second Threshold IZE should be less than the peak value of its initial value or first threshold IAAM.
The maximum ON time that control circuit 500 comprises arranging maximum ON time TMAX alternatively arranges circuit, when the ON time of high-side switch M1 is more than the second ON time TON2 (i.e. maximum ON time), turns off high-side switch M1.Threshold value in Fig. 5 arranges circuit 504 can have the function that maximum ON time arranges circuit, such as, when the ON time of high-side switch M1 is more than the second ON time TON2, directly first threshold IAAM is decreased to zero, to such an extent as to the first comparison circuit 203 outputs signal directly upset for high level, and then turn off high-side switch M1.Maximum ON time arranges circuit input end can be coupled to the first switching signal DL1 to monitor the ON time of the first switch; Also can be coupled to one end of the first switch M1, the electric current according to the first switch M1 judges its conducting state, and then determines ON time; Can also be coupled to cut-off signals SETOFF, be that the second state starts timing from cut-off signals SETOFF upset, or a time period after cut-off signals SETOFF upset is the second state starts timing.The output that maximum ON time arranges circuit can be coupled to arbitrary input or the output of the first comparison circuit 203, such as pass through first threshold IAAM quick pull-down, or by the quick pull-up of signal of reaction high-side switch electric current I M1, or directly change the state that cut-off signals produces circuit 203 output signal, and then turn off high side power switch M1.Maximum ON time arranges circuit directly can also change the state of the output signal of logical circuit 205 to turn off high-side switch M1.
Although the utility model is described in conjunction with its concrete illustrative embodiments, it is apparent that multiple alternative, amendment and distortion be apparent for those skilled in the art.Thus, the illustrative embodiments of the present utility model illustrated at this is schematic and and non-limiting.Can modify when not departing from spirit and scope of the present utility model.
Used in this disclosure measure word " ", " one " etc. do not get rid of plural number." first ", " second " in literary composition etc. only represent the sequencing occurred in describing the embodiments of the present, so that distinguish like." first ", " second " go out to be now only and be convenient to the fast understanding of claim instead of in order to be limited in detail in the claims.Any Reference numeral in claims all should not be construed as the restriction to scope.
Claims (14)
1., for a control circuit for dc-dc converter, described dc-dc converter has high-side switch and the low side switch of coupled in series, 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, provides cut-off signals, and described cut-off signals is the second state by the first state turnover at the end of setting-up time;
First comparison circuit, the comparative result based on high-side switch electric current and first threshold provides the first comparison signal;
Second comparison circuit, the comparative result based on low side switch electric current and Second Threshold provides the second comparison signal, and wherein Second Threshold is less than first threshold;
Logical circuit, there is first input end, second input, 3rd input, four-input terminal, first output and the second output, based on described Continuity signal, described cut-off signals, described first comparison signal and described second comparison signal provide the first switching signal to control conducting and the shutoff of described high-side switch at its first output, there is provided second switch signal to control conducting and the shutoff of described low side switch at its second output, wherein, at the end of described setting-up time, if described high-side switch electric current is less than described first threshold, described high-side switch by maintenance conducting until described high-side switch electric current is equal to, or greater than described first threshold.
2. control circuit according to claim 1, it is characterized in that, at the end of described setting-up time, if described high-side switch electric current is less than described first threshold, described first comparison signal makes described high-side switch keep conducting by the described cut-off signals of shielding or described first switching signal.
3. control circuit according to claim 1 and 2, is characterized in that, when described cut-off signals has the first state, described high-side switch keeps conducting; When described cut-off signals has the second state, when described high-side switch electric current increases to described first threshold, described first switching signal turns off described high-side switch.
4. control circuit according to claim 1, is characterized in that, in described setting-up time, if described high-side switch electric current is greater than or equal to described first threshold, described first switching signal turns off described high-side switch at the end of described setting-up time.
5. control circuit according to claim 4, is characterized in that,
When described high-side switch electric current is less than described first threshold, described first comparison signal has the first state; When described high-side switch electric current is greater than described first threshold, described first comparison signal has the second state;
In described setting-up time, if described first comparison signal has the second state, when described cut-off signals upset is the second state, described first switching signal turns off described high-side switch.
6. control circuit according to claim 1, it is characterized in that, described high-side switch has first end, the second end and control end, its first end receives input voltage, its control end receives described first switching signal: described low side switch has first end, the second end and control end, its first end is coupled to the second end of described high-side switch, and its second end is coupled to earth terminal, and its control end is coupled to described second switch signal; Described dc-dc converter also comprises:
Inductor, has first end and the second end, and wherein first end is electrically connected to the second end of described high-side switch, and its second end provides output voltage; And
Output capacitance, has first end and the second end, and wherein first end is coupled to the second end of described inductance, and its second end is coupled to earth terminal.
7. control circuit according to claim 1, is characterized in that, described Continuity signal produces circuit and comprises:
First amplifier, comprises first input end, the second input and output, and its first input end and the second input are configured to first input end and second input of described turning circuit respectively; And
First voltage comparator, comprise first input end, the second input and output, its first input end is coupled to the output of described first amplifier, its second input is coupled to the second input of described first amplifier, and its output is configured to the output that described Continuity signal produces circuit.
8. control circuit according to claim 1, is characterized in that, described cut-off signals produces circuit and comprises timing circuit, when the time zero of described setting-up time is described high-side switch conducting.
9. control circuit according to claim 1, is characterized in that, described cut-off signals produces circuit and comprises,
First electric capacity, has first end and the second end, and its second end is coupled to earth terminal;
First switch, has first end, the second end and control end, and its first end and the second end are coupled to the two ends of described first electric capacity respectively, and its control end is coupled to described first switching signal;
First current source, have first end, the second end, its first end is coupled to the input voltage of described dc-dc converter, and its second end is coupled to the first end of described first electric capacity;
Second voltage comparator, has first input end, the second input and output, and its first input end is coupled to the first end of described first electric capacity, and its second termination receives voltage compare threshold value, and output provides described cut-off signals.
10. control circuit according to claim 9, is characterized in that, the electric current of described first current source is directly proportional or linear relationship to the input and output voltage ratio of described dc-dc converter.
11. control circuits according to claim 1, it is characterized in that, also comprise the threshold adjustment circuit adjusting described first threshold, after described high-side switch ON time is more than the first ON time, described threshold value arranges circuit and reduces described first threshold, and wherein said first ON time is more than or equal to zero.
12. control circuits according to claim 1, is characterized in that, also comprise maximum ON time and arrange circuit, when the ON time of described high-side switch is more than the second ON time, and high-side switch described in described maximum ON time circuit shut-down.
13. control circuits according to claim 1, is characterized in that, described logical circuit comprises
First logical circuit, have first input end, the second input and output, its first input end receives described cut-off signals, and its second input receives described first comparison signal;
Trigger logic, there is first input end, the second input, the first output and the second output, wherein first input end is coupled to the output of described first logical circuit, its second input receives described Continuity signal, its the first output end provides described first drive singal, and its second output provides driving reverse signal; And
Second logical circuit, has first input end, the second input and output, and its first input end receives described driving reverse signal, and its second input receives described second comparison signal, and its output provides described second drive singal.
14. control circuits according to claim 13, is characterized in that, described first logical circuit is and logical circuit, and described trigger logic is RS trigger logic, and described second logical circuit is and logical circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420585345.3U CN204131395U (en) | 2014-10-11 | 2014-10-11 | Control circuit for switching converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420585345.3U CN204131395U (en) | 2014-10-11 | 2014-10-11 | Control circuit for switching converter |
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| Publication Number | Publication Date |
|---|---|
| CN204131395U true CN204131395U (en) | 2015-01-28 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420585345.3U Withdrawn - After Issue CN204131395U (en) | 2014-10-11 | 2014-10-11 | Control circuit for switching converter |
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| CN (1) | CN204131395U (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104242644A (en) * | 2014-10-11 | 2014-12-24 | 成都芯源系统有限公司 | Control circuit and control method for switching converter |
| CN105471230B (en) * | 2016-01-07 | 2018-05-22 | 成都芯源系统有限公司 | Switching power converter and control method thereof |
| TWI636654B (en) * | 2016-10-09 | 2018-09-21 | 昂寶電子（上海）有限公司 | Buck converter and control method thereof |
| US20210124382A1 (en) * | 2019-10-25 | 2021-04-29 | Intel Corporation | Enhanced constant-on-time buck intellectual property apparatus and method |
| CN113872421A (en) * | 2020-10-30 | 2021-12-31 | 成都芯源系统有限公司 | Control circuit of voltage conversion circuit and control method thereof |
| CN116131606A (en) * | 2023-04-18 | 2023-05-16 | 晶艺半导体有限公司 | Control circuit, system and method for switching converter |
-
2014
- 2014-10-11 CN CN201420585345.3U patent/CN204131395U/en not_active Withdrawn - After Issue
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104242644A (en) * | 2014-10-11 | 2014-12-24 | 成都芯源系统有限公司 | Control circuit and control method for switching converter |
| CN104242644B (en) * | 2014-10-11 | 2017-04-12 | 成都芯源系统有限公司 | Control circuit and control method for switching converter |
| CN105471230B (en) * | 2016-01-07 | 2018-05-22 | 成都芯源系统有限公司 | Switching power converter and control method thereof |
| TWI636654B (en) * | 2016-10-09 | 2018-09-21 | 昂寶電子（上海）有限公司 | Buck converter and control method thereof |
| US20210124382A1 (en) * | 2019-10-25 | 2021-04-29 | Intel Corporation | Enhanced constant-on-time buck intellectual property apparatus and method |
| US11742754B2 (en) * | 2019-10-25 | 2023-08-29 | Intel Corporation | Enhanced constant-on-time buck intellectual property apparatus and method |
| CN113872421A (en) * | 2020-10-30 | 2021-12-31 | 成都芯源系统有限公司 | Control circuit of voltage conversion circuit and control method thereof |
| CN116131606A (en) * | 2023-04-18 | 2023-05-16 | 晶艺半导体有限公司 | Control circuit, system and method for switching converter |
| CN116131606B (en) * | 2023-04-18 | 2023-07-25 | 晶艺半导体有限公司 | Control circuit, system and method for switching converter |
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| C14 | Grant of patent or utility model | ||
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Granted publication date: 20150128 Effective date of abandoning: 20170412 |