CN103618453A - Switching regulator circuit - Google Patents
Switching regulator circuit Download PDFInfo
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- CN103618453A CN103618453A CN201310612898.3A CN201310612898A CN103618453A CN 103618453 A CN103618453 A CN 103618453A CN 201310612898 A CN201310612898 A CN 201310612898A CN 103618453 A CN103618453 A CN 103618453A
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Abstract
The invention provides a switching regulator circuit used for controlling a switching regulator. The switching regulator (1) is provided with an output end comprising one ore more switches for switching transistors and an output capacitor used for providing current to a load under a stable voltage. When the voltage of the output end can basically be kept at the adjusted voltage due to the charging of the output capacitor, a control circuit generates one or more control signals to switch off the switching transistors. By the adoption of the switching regulator circuit, the work efficiency of a circuit of the switching regulator can be improved especially on a low current level.
Description
Technical field:
The present invention relates to a kind of switching regulator circuit.More specifically, the present invention relates to can in wide-range current, keep efficient control circuit and method in switch voltage-stabilizing circuit.
Background technology:
The object of voltage regulator is for load provides a kind of predetermined and constant output voltage, and input voltage source may fluctuate.In general, there are two kinds of dissimilar pressurizers: series voltage regulator and switching regulator.
Series voltage regulator adopts the element (for example power transistor) together with load series coupled, to control the voltage drop at these element two ends, thereby adjusts the voltage of present load end.In contrast, the switch (for example power transistor) that switching regulator adopts is of coupled connections with load serial or parallel connection.The opening and closing of pressurizer control switch, to regulate the power of supply load.Switching regulator adopts inductive energy storage element, thereby converts current impulse to stable load current.Therefore, the power of switching regulator is sent out with discrete current impulse form, and in a series voltage regulator, the power of pressurizer is sent out with stable current forms.
For generation current pulse, switching regulator generally includes control circuit, to open and close switch.The duty ratio of switch (power providing to load is provided for it) can change by several different methods.For example, duty ratio can change by the following method: (1) fixed pulse frequency and change the duty ratio of each pulse, (2) are fixed the duty ratio of each pulse and changed pulse frequency.
No matter adopt which kind of method to control duty ratio, switching regulator is generally all higher than the efficiency of series voltage regulator.In series voltage regulator, bypass elements is generally operational in the ， range of linearity, its range of linearity, the continuous On current of bypass elements.This will cause the continuous power dissipation of transistor.On the contrary, in switching regulator, switch is in off-state (there is no power dissipation under this state) or conducting state (low impedance state has less power dissipation under this state).This species diversity conventionally can cause the minimizing of the average power consumption of switching regulator when operation.
Poor when larger when the input-output terminal voltage of pressurizer, the difference in above-mentioned efficiency will be more clear.For example, under equivalent function, the efficiency of series voltage regulator is lower than 25%, and the efficiency of switching regulator can be greater than 75%.
Due to switching regulator, compare have higher efficiency with series voltage regulator, switching regulator adopts battery power supply system conventionally, as portable notebook computer and handheld instrument.In such system, for example, when the electric current of switching regulator approaches rated value (disk of notebook computer and hard disk drive are all when work), the efficiency of whole circuit can be very high.Yet efficiency is a function relevant to output current normally, and output current power reduction while reducing.The reduction of this efficiency is generally the loss causing due to console switch pressurizer.These losses comprise: the static current consumption of control circuit, switching loss (current loss of switch drive and the winding of inductor/transformer and core loss) in pressurizer.
In battery powered system, the minimizing of switching regulator efficiency when low output current is just very important, and this will make the lifetime of battery.
In view of the foregoing, provide high efficiency switching regulator to need.
In switch voltage-stabilizing circuit, provide in wide-range current (comprising low output current) that to keep efficient control circuit and method be also needs.
Summary of the invention:
Therefore, an object of the present invention is to provide a kind of efficient switching regulator.
Another object of the present invention is in switch voltage-stabilizing circuit, provides and in wide-range current (comprising low output current), keeps efficient control circuit and method.
Technical solution of the present invention:
According to the above-mentioned object with other, the invention provides a kind of circuit and method for controlling a switching regulator, it comprises that (1) comprises the switch of one or more switching transistors, (2) be suitable for for load, supplying with the output of electric current under a stable voltage, it comprises an output capacitance.For example, when the voltage of output can remain essentially in the voltage after adjusting due to the charging of output capacitance when low output current (), above-mentioned control circuit generates one or more control signals with stopcock transistor.During this, load is not from input power source consumed power.Therefore, pressurizer increases efficiency.If necessary, other element in switching regulator also can specially be turn-offed to save power consumption.This additional functionality of the present invention can further improve the efficiency of whole voltage regulator circuit.
Circuit of the present invention and method can be used for polytype switch in control switch voltage regulator circuit, comprise the switch that uses one or more power transistors.In addition, circuit of the present invention and method can be used in dissimilar switching regulator, comprise that voltage drop, voltage rise and polarity inversion circuit.
In addition,, in response to input voltage and the output voltage of switching regulator, circuit of the present invention and method can change the turn-off time of switching transistor.In low input situation, this feature of the present invention can reduce the audible noise obtaining from switching regulator.During the output voltage short circuit of some pressurizers, it is out of control that it has also reduced potential electric current.
Contrast patent documentation: CN202385004U power supply switching circuit of voltage regulation 201220019682.7, CN203251234U switch power voltage-stabilizing circuit 201320245393.3
Accompanying drawing explanation:
Fig. 1 is the switching regulator circuit diagram of a typical prior art, comprises the switch mosfet of a pair of synchronous switching;
Fig. 2 is a switching regulator circuit diagram, by efficient control circuit of the present invention, carrys out driving switch, comprises the MOSFET of a pair of synchronous switching;
Fig. 3 is a switching regulator circuit diagram, by efficient control circuit of the present invention, carrys out driving switch, comprises a switch MOS FET and a switching diode;
Fig. 4 is a switching regulator circuit diagram, by efficient control circuit of the present invention, with " user's activation " form, carrys out driving switch, comprises the MOSFET of a pair of synchronous switching;
Fig. 5 is a switching regulator circuit diagram, by variable turn-off time control circuit of the present invention;
Fig. 6 is a detailed maps of variable turn-off time control circuit in Fig. 5;
Fig. 7 is a detailed switching regulator circuit diagram, by variable turn-off time of the present invention and efficient control circuit, carrys out driving switch, comprises the MOSFET of a pair of synchronous switching;
Fig. 8 is a switching regulator circuit diagram, prevents the polarity inversion of electric current in outputting inductance by a circuit of the present invention;
Fig. 9 is a switching regulator circuit diagram, by the present invention boost configuration efficient control circuit carry out driving switch;
Figure 10 is a switching regulator circuit diagram, and the efficient control circuit configuring by polarity inversion of the present invention carrys out driving switch.
Embodiment:
Fig. 1 is the switching regulator circuit diagram of a typical prior art, adopts and recommends switch.
With reference to Fig. 1, circuit 10 is used to provide at terminal 12 the VD V regulating
oUT(for example 5 volts), for driving load 14, wherein, load 14 may be a portable computer or other battery powered system.Circuit 10 is connected to the supply voltage V without voltage stabilizing from terminal 14
iN(for example battery of 12 volts).Circuit 10 comprises push-pull type switch 15, drive circuit 20, output circuit 30 and control circuit 35.
Control circuit 35 comprises: single-shot trigger circuit 25, and it provides a constant shutoff pulse (for example 2 to 10 microseconds), and during this period, MOSFET16 and MOSFET17 are kept turn-offing and conducting by driver 26 and 27 respectively.Otherwise single-shot trigger circuit 25 provides a conducting pulse, during this period of time, MOSFET16 and MOSFET17 are held respectively turn-on and turn-off.Therefore, single-shot trigger circuit 25 is turn-on and turn-off MOSFET16 and 17 alternately, thereby for output circuit 30 provides an electric current supply replacing, the duty ratio of single-shot trigger circuit 25 is controlled by current comparator 39.
Control circuit 35 is by resistive divider network R1/R2(36A/36B) monitoring output voltage V
oUT, to provide and output voltage V
oUTproportional feedback voltage V
fB.Control circuit 35 is also monitored by the electric current I of inductance L 1
l, so that one and inductive current I to be provided
lproportional feedback current I
fB.Circuit 10 is by controlling inductive current I
l, make feedback voltage V
fBbe adjusted to the reference voltage V that provided by reference circuit 37 is provided
rEF.Along with feedback voltage V
fBbe conditioned output voltage V
oUTbe adjusted to higher voltage ratio (ratio of R1+R2 and R2).
Along with the increase of output load current, resistance R 2(36B) voltage drop at two ends will reduce.This is converted into the upper little error voltage of trsanscondutance amplifier 38 input 38B, and this error voltage will cause exporting 38A to be increased, thereby is that current comparator 39 is set higher threshold value.Correspondingly, the electric current I in inductance L 1
lincrease to needed level, with holding load electric current.
Turn-off time (t due to single-shot trigger circuit 25
oFF) be constant, switching regulator circuit 10 has a constant ripple current in inductance L 1, thereby produces a constant output voltage V
oUT, but have a frequency changing with input voltage.The frequency of oscillation of ripple is provided by following formula:
In Fig. 1, first shortcoming of circuit 10 is at lower input voltage V
iNtime, the frequency of oscillation f of ripple
rIFmay be reduced to lower level.This is contingent, for example, and when a battery powered switching regulator circuit does not almost have electricity.At this moment inductance L 1 may produce and send noise, and this is to adopt the user of mobile device of voltage stabilizing circuit undesirable.
Second shortcoming of circuit 10 is to work as output voltage V
oUTduring ground connection, inductive current I
lbe not well controlled.The electric current of inductance and the fundamental relation between voltage are provided by following formula: di/dt=V/L.This means the electric current I in inductance L 1
lthe rate dependent decaying at blocking interval is in the voltage at inductance L 1 two ends, and this voltage is V
oUTdrain electrode-source voltage V with N-channel MOS FET17
dSpoor.Work as V
oUTlevel off to zero, and V
dSwhen also very low, will cause at t
oFFthe electric current I of time period internal inductance L1
ldecay less.Yet within each shutoff cycle, 16 conductings of P channel mosfet, until current comparator 39 triggers single trigger control circuit 25 again.Even P channel mosfet 16 conductings within the shortest time, the electric current I in inductance L 1
lmay be to surpass it at t
oFFthe speed reducing in time period increases.This may cause a runaway condition, and the short circuit current under this runaway condition may reach destructive level.
The 3rd shortcoming of circuit 10 is that ripple current constant in inductance L 1 causes.Within the shutoff cycle, the electric current I in inductance L 1
lalways with identical speed, decline gradually, and no matter why the output current of pressurizer is worth.When output current is lower, this may cause the current polarity reversion in inductance L 1, and obtains power from load.During the ensuing closed cycle, this electric current again become on the occasion of, make average inductor current equal load current.This constant ripple current can cause relevant loss, because the charging and discharging of the MOSFET grid of switch 15 will cause switching losses, the reduction of efficiency when this can cause low output current.If the current reversal in inductance L 1 is also passed through N-channel MOS FET17 from load draw power, this situation can be more serious.
The 4th shortcoming of circuit 10 is that gate circuit drives P channel mosfet 16 and N-channel MOS FET17.Postpone to be included into driver 26 and 27, to guarantee that a power MOSFET turn-offed before other closures.If there is no enough Dead Times (for example, due to equipment, processing of circuit or variations in temperature) between two MOSFET, electric current will be directly from input power V
iNflow to ground.This " short circuit " situation will greatly lower efficiency, and in some cases may be overheated and destroy power MOSFET.
Fig. 2 is a switching regulator circuit diagram, by efficient control circuit of the present invention, carrys out driving switch, comprises the MOSFET of a pair of synchronous switching.
Similar with Fig. 1, switch voltage-stabilizing circuit 50 comprises recommends switch 15, drive circuit 20 and output circuit 30.Circuit 50 also comprises an example 70 of high efficiency control circuit of the present invention.
Similar with Fig. 1, control circuit 70 comprises single-shot trigger circuit 25, current comparator 39 and amplifier 38.Yet except these elements, control circuit 70 also comprises constant current source 72(I1) and hysteresis comparator 74, for high efficiency operation is provided under low average current.
As discussing in more detail below, constant current source 72 and comparator 74 allow to recommend switch 15 and enter state below: MOSFET16 and 17 and turn-off simultaneously, output voltage V
oUTdue to output capacitance C
oUTcan be substantially equal to regulation voltage V
rEG.This mode of operation is called as " sleep pattern " in this article.If make the switch 15 of recommending in Fig. 1 enter such sleep pattern, MOSFET16 and 17 one of them conducting at any time.This feature of the present invention has reduced the power consumption of voltage regulator circuit because recommend not consumed power of switch 15, or allow power supply in sleep pattern by meeting load R
lthen ground connection.
In addition,, if recommend switch 15 in above-mentioned sleep pattern, voltage regulator circuit can disconnect some other circuit devcies that do not need work.For example, for Fig. 2 of the present invention, implement, single-shot trigger circuit 25, current comparator 39, current source 72 and amplifier 38 also can be closed and make it in sleep pattern.If only recommend switch 15, be maintained under sleep pattern, this feature of the present invention allows voltage regulator circuit to be operated under higher efficiency.
For example, under high load currents (be greater than maximum rated output current 20%), the class of operation of control circuit 70 is similar to the control circuit 35 in Fig. 1.As shown in Figure 2, feedback current I
fBagain be provided to the non-inverting input of current comparator 39.Offset voltage V
oS(76) be preferably built in amplifier 38 feedback voltage V
fBslightly lower than reference voltage V
rEFthereby, guarantee hysteresis comparator 74 output high level under high current condition.As feedback current I
fBsurpass while being supplied to the electric current of comparator 39 inverting inputs, the output of comparator 39 becomes high level, so that starting switch is to the shutoff cycle.
Within the shutoff cycle, the output 25A of single-shot trigger circuit 25 be high level time, P channel mosfet 16 is turn-offed and N-channel MOS FET17 closed.After the constant time that single-shot trigger circuit 25 sets, output 25A becomes low level, thereby starts the next closed cycle, P channel mosfet 16 closures wherein, and N-channel MOS FET17 turn-offs.
According to the present invention, under low output current level, adjuster circuit 50 enters sleep pattern as follows.Hysteresis comparator 74 monitoring feedback voltage V
fB, and work as V
fBsurpass a predetermined magnitude of voltage (reference voltage V
rEF) time become low level.This represents output voltage V
oUTsurpass a predetermined magnitude of voltage (regulation voltage V
rEG).Due to constant current source 72 and amplifier 38 parallel coupled, when lower average output current, will there will be above-mentioned overpressure conditions.Under overpressure condition, MOSFET16 and 17 is by keeping turn-offing with door 66 and NAND gate 68.
Constant-current source 11 is provided with a minimum feedback current threshold value for current comparator 39.This will be for inductor L1 arranges a minimum current, and it is in each closed cycle trigger comparator 39.According to the present invention, it is closed that current comparator 39 is held, otherwise will cause it to trigger.Therefore, for inductor L1 provides than required more electric current, to maintain output voltage V
oUTbe substantially equal to regulation voltage V
rEG.Finally, V
oUTto start to surpass regulation voltage V
rEG, cause feedback voltage V
fBat a predetermined magnitude of voltage V
rEFlower triggering hysteresis comparator 74.After comparator 74 triggers, its output becomes low level turn-offs two MOSFET16 and 17, thereby makes voltage regulator circuit enter sleep pattern.
In above-mentioned sleep pattern, MOSFET16 and 17 turn-offs simultaneously, and output loading 14 is substantially by output capacitance C
oUTdetermine.Hysteresis comparator 74 monitoring feedback voltage V
fB, work as V
oUTwhile dropping to certain level, drive circuit 20 is no longer in sleep pattern (wherein MOSFET16 and 17 is turned off), thereby again for load 14 provides electric current.If load current is still on the low side, C
oUTcharge to and surpass V
rEGvoltage levvl, through several all after dates, feedback voltage V
fBtrigger comparator 74 again.
Therefore, when underload, control circuit 70 turn-offs MOSFET16 and MOSFET17, and now they do not need to keep output voltage in regulation voltage level, but by output capacitance C
oUTcomplete such function.When the output voltage under this pattern drops to lower than regulation voltage level, control circuit 70 makes switch 15 closures, thereby is output capacitance C
oUTcharge to and surpass regulation voltage.Therefore, V
oUTto between upper lower threshold value, vibrate, its parameter is multiplied by (R1+R2) by the lagging voltage of comparator 74 and determines with the ratio of R2.Pressurizer " wakes up " thereby is output capacitance C
oUTthe speed of charging can automatically adapt to load current, even also can keep high efficiency under low output current.
According to the present invention, thereby as the enough low permission output capacitance C of output current
oUTwhen maintaining output voltage and being substantially equal to regulation voltage, control circuit 70 makes MOSFET16 and 17 keep turn-offing.Generally, even if MOSFET16 and 17 is held to turn-off switching regulator when a stable voltage is provided, the time of this shutoff can extend to over several seconds (for the switching frequency of 100 KHz, corresponding respectively to several switch periods and hundreds of to thousands of switch periods) from being less than 100 microseconds.Such turn-off time can obtain greater efficiency (for example surpassing 90%) conventionally, and output current scope can surpass 100:1.Except switching transistor, other device also can be held to turn-off in the meantime, therefore even can obtain higher efficiency.
As shown in Figure 2, the control circuit 70 of switching regulator 50 is used to drive a synchronous diverter switch, and this switch comprises MOSFET16 and 17.As used herein, term " synchronous diverter switch " refers to the switch that comprises two switching transistors, and it is load supply electric current under a stable voltage.Fig. 3 shows second example of high efficiency control circuit of the present invention, and it is suitable for driving the configuration of step-down to comprise the switching circuit of a switching transistor and switching diode.
As shown in Figure 3, switch voltage-stabilizing circuit 100 comprises switch 115, and it is comprised of P channel mosfet 116 and diode 118.Switch 115 is driven by driver 120, and it is comprised of P raceway groove driver 126.The closed and disconnected of switch 115 is controlled by control circuit 125.Because control circuit 125 is only for driving a MOSFET(with respect to the control circuit 70 of Fig. 2), it only has the output of a lead-out terminal 125A(NAND gate 68).
Similar with the control circuit 70 in Fig. 2, control circuit 125 comprises current comparator 39, amplifier 38, hysteresis comparator 74, single-shot trigger circuit 25.For Fig. 2, under lower average output current, constant current source 72 is used to inductance L 1 that overcurrent is provided, to make output voltage V
oUTbe increased to regulation voltage V
rEGon, at this moment output voltage can be substantially by output capacitance C
oUTprovide.During, P channel mosfet 116 remains under sleep pattern, to increase the efficiency of circuit.
As discussed above, the control circuit 125 in the control circuit in Fig. 2 70 and Fig. 3 provides respectively high efficiency operation under lower average output current.Such operation can automatically adapt to output current.For example, under High Output Current, switch constantly replaces between closure state and off-state, to maintain output voltage V
oUTat regulation voltage V
rEGplace.Under low output current, the efficiency of circuit is lower, output voltage V
oUTalso be substantially equal to regulation voltage V
rEG, this is constantly alternately realized by output capacitance rather than switch between closed and disconnected state.Therefore, above-mentioned control circuit is automatically identified such condition, thereby allows voltage stabilizing circuit to enter " sleep " pattern, at this moment only needs the circuit element of minimum number in running order.
According to another feature of the present invention, whether voltage stabilizing circuit can also, in conjunction with the control circuit of " user's activation ", be to enter " sleep " pattern thereby control voltage stabilizing circuit by user.Fig. 4 is a switching regulator circuit diagram, by efficient control circuit of the present invention, with above-mentioned " user's activation " form, carrys out driving switch, comprises the MOSFET of a pair of synchronous switching.
Similar with the circuit 50 in Fig. 2, the switch voltage-stabilizing circuit 150 in Fig. 4 comprises push-pull driver 20, switch 15, output circuit 30.Circuit 50 equally and in Fig. 2 is similar, and the control circuit 170 of voltage stabilizing circuit 150 comprises single-shot trigger circuit 25, current comparator 39 and amplifier 38.Switch 175 comprises switch 176 and 178, inputs 175A voltage stabilizing circuit 150 is switched to sleep pattern by user, and input 175A may be the control signal that the control circuit (not shown in FIG.) by other types obtains.When closing switch 175,176 and 178 all close.
As discussed above, control circuit 170 periodically departs from sleep pattern, by P channel mosfet 16 closures, thinks output capacitor C
oUTcharging.Although under ordinary skill, N-channel MOS FET15 is held to turn-off, and is not necessary under the present invention.For example,, when control circuit 170 is output capacitance C
oUTduring charging, such charging can realize by alternately making switching transistor turn-off, to change duty ratio, is also output capacitance C
oUTcharging.
Similar with the regulating circuit 50 in Fig. 2, voltage stabilizing circuit 150 works to raise the efficiency under low current level.Yet, the voltage stabilizing circuit 50 in comparison diagram 2, regulating circuit 150 can automatically not adapt to output current.For example, circuit 150 can automatic trip when average output current increases from sleep pattern--it depends on user's operation.
As discussed above, the control circuit example of the present invention that is shown in Fig. 2-4 comprises single-shot trigger circuit 25.According to another feature of the present invention, single-shot trigger circuit can be replaced the duty ratio with power ratio control switch by the circuit of other types.For example, single-shot trigger circuit 25 can be replaced by a pulse-width modulator circuit, and this Circuit responce is the width with modulating pulse in a control signal.Certainly, also can use the circuit of other types.
According to another feature of the present invention, provide the single-shot trigger circuit 25 of a constant turn-off time signal can be replaced by the single-shot trigger circuit that a variable turn-off time signal is provided, this variable time depends on output voltage (V
oUT) and input voltage (V
iN).This feature of the present invention can be used to reduce the noise in inductor L1 under low input.As discussed above, such noise is relevant with the vibration of inductive current.In addition,, if output short-circuit, this feature of the present invention also can be used to control short circuit current.
Fig. 5 is a switching regulator circuit diagram, by variable turn-off time control circuit of the present invention.
Switch voltage-stabilizing circuit 200 comprises: recommend switch 15, drive circuit 20, current feedback circuit 210, voltage feedback circuit 220, feedback control circuit 230 and variable turn-off time circuit 240.Feedback control circuit 230 monitors output current and output voltage by input 232 and 234 respectively, and provides a triggering signal at terminal 236, with the shutoff cycle of starting switch 15.Variable turn-off time circuit 240 is controlled the turn-off time as follows.
Circuit 240 comprises single trigger 245, and it is triggered by terminal 236 by feedback control circuit 230.Single trigger 245 comprises an extra terminal 245A, and it is coupled to control capacitance 246(C
cON), the voltage of this electric capacity is monitored by generator 245.According to the present invention, turn-off time control circuit 250 control capacitance C
cONelectric discharge, thereby turn-off time of control generator 245 conversely.Turn-off time control circuit 250 monitoring input and output voltage (V
iNand V
oUT), and correspondingly adjust the turn-off time according to their value.
According to the present invention, if input voltage V
iNreduce, make the frequency of oscillation f of inductance L 1
rIPfall into the range of audibility discussed above, turn-off time reduction makes f
rIPcorrespondingly increase and exceed above-mentioned scope.In addition, if output voltage V
oUTbecause short circuit reduces, the voltage at inductance L 1 two ends is too low and can not allow inductive current within the turn-off time, to have enough decay, and the turn-off time increases to avoid the runaway condition of electric current.
In this example, control capacitance C
cONelectric discharge by control, control the size adjustment of electric current.For example, under low input, turn-off time control circuit 250 makes I
cONincrease control capacitance C
cONon voltage decline rapidly.When the voltage drop of control capacitance arrives lower than a predetermined value, the closed cycle of switch 15 is activated.In addition,, under low output voltage, turn-off time control circuit 250 makes I
cONdecline, make control capacitance C
cONon voltage slow-decay, to extend the turn-off time.
Although the switch voltage-stabilizing circuit 200 in Fig. 5 depends on specific circuit, be used to capacitor discharge to control the turn-off time, clearly, in response to input voltage, also can be used with output voltage the circuit identical with foregoing circuit function.For example, if necessary, an operational amplifier can be for controlling the turn-off time.
Therefore, single-shot trigger circuit discussed above provides a variable turn-off time according to input and output voltage.This feature of the present invention is (to reduce t for example, during at low input for reducing the audible noise of voltage stabilizing circuit when the low input
oFF), and limiting short-circuit current (for example increases t when low input when output short-circuit
oFF).
Fig. 6 is a detailed maps of variable turn-off time control circuit in Fig. 5.
Turn-off time control circuit 250 is accepted V at terminal 252 and 254 respectively
iNand V
oUT, and provide an output I at terminal 256
cON.As discussed above, I
cONdetermine control capacitance C
cONwhether discharge, this is capacitively coupled to terminal 256.Control circuit 250 is controlled I
cONamplitude, therefore and control control capacitance C
cONthe time that electric discharge spends.Control circuit 250 comprises that current source 260(is for providing electric current I
cN2), current source 270(is used for providing electric current I
cN1), current compensation circuit 280 and current mirror output circuit 295.The operation principle of control circuit 250 is as described below.
Current mirror output circuit 295 comprises that transistor 296 and its grid of transistor 298(298A are connected to its drain electrode 298B), they form a current mirror circuit.Circuit 295 is accepted a steered reference electric current I from input 295A
cREF, and provide an output current I according to the ratio of transistor 296 and 298
cON(similar with traditional current mirror circuit).According to the present invention, I
cREFequal I
cN1still (I
cN1+ I
cN2) depend on the voltage V of input 252 and 254
iNand V
oUT.
Work as V
iN-V
oUTwhile being greater than 1.5 volts, transistor 262 produces enough electric currents (being supplied with by transistor 264 and current source I6), to keep transistor 266 to turn-off.Along with the shutoff of transistor 266, electric current I
cN2by vanishing, electric current I
cREFtherefore the electric current I of current source 270 lead-out terminal 270A will be equaled
cN1.
Electric current I
cN1by a current mirroring circuit, supplied with, it is connected to its drain electrode 274B by transistor 272 and its grid of transistor 274(274A) form.According to the present invention, the reference current I flowing through in transistor 274
cN1REFequal I
cN1Astill (I
cN1A+ I
cN1B), depend on that transmission gate 282 is opened or closure.
Transmission gate 282 is controlled by comparator 284, works as V
oUTlower than V
tH3in time, will open.Opening under condition I
cN1REFequal I
cN1A, i.e. the collector current of transistor 276.This electric current comes from V
oUTwith voltage divider (being formed by resistance 271 and 273), to produce voltage V
fB1(base stage of transistor 279).Voltage V
fB1the base-emitter voltage that equals transistor 276 adds that the voltage at resistance 278 two ends deducts the base-emitter voltage of transistor 279.So the collector current of transistor 276 is and output voltage V
oUTproportional, cause control capacitance C
cONthe speed of electric discharge is proportional to the discharge rate of electric current in inductance L 1.
Therefore, work as output voltage V
oUTwhen lower, for example, under fault or starting state, t
oFFby being extended, allow the electric current in extra time internal inductance device L1 sharply to decline.
Work as output voltage V
oUTbe greater than V
tH3time, the output closing transmission door 282 of comparator 284, makes additional offset current I
cN1Bbe coupled to the drain electrode of transistor 274, thereby provide current compensation by current compensation circuit 280.Offset current I
cN1Bequal electric current I
tRIMdeduct the drain current of transistor 286.Transistor 286 and 288 forms image current mirrors, and their collector current equals the collector current of transistor 290, and (be similar to the collector current of transistor 276 discussed above, difference is voltage I
rEFreplace voltage V
fB1be used).
Offset current I
cN1Bthere are two objects: 1) work as output voltage V
oUTwhile being substantially equal to its regulation voltage, during as the electric current of a finishing, set the I of required control electric current
cON, 2) and in very wide operating temperature range, keep substantially invariable control electric current I
cON.In typical circuit fabrication process, the variation of resistance 278 resistances can cause controlling electric current I conventionally
cONmore greater or lesser than what expect.And aborning by adjusting I
tRIM, offset current I
cN1Bcan be adjusted the collector current (I that makes transistor 276
cN1A) be increased as requested or reduce, so that a predetermined control electric current I to be provided
cON.In addition,, if resistance 278 matches with 292 (being that designing and making process is identical), because the resistance variation with temperature of resistance 278 and resistance 292 has identical variation, control electric current I
cONto there is no variation.
If output voltage V
oUTbe less than V
tH3, transmission gate 282 is opened in the output of comparator 284, thereby suppresses current compensation.This will guarantee to control electric current I
cINalong with output voltage V
oUTlevel off to zero and approach zero, thereby guarantee inductive current I during output short-circuit
lcontrolled.
Work as V
iNdrop to V
iN-V
oUTwhile being less than 1.5 volts, the electric current in transistor 262 no longer makes transistor 266 in off state.Along with V
iNfurther reduce, transistor 266 is by extra electric current (I
cN2) be added in current mirror output circuit 295, thereby improve, control electric current I
cON, reduce t simultaneously
oFF.Along with t
oFFreduce, this makes again operating frequency become stable conversely, has reduced potential noise problem.Current source I
7determined that transistor 266 is increased to control electric current I
cONmaximum current.
Therefore, work as V
iNdrop to V
iN-V
oUTfor example, while being less than 1.5 volts (when the approaching no electricity of battery), t
oFFthe frequency of oscillation of voltage stabilizing circuit will be reduced to increase, to reduce audible noise.
Although variable turn-off time control circuit 250 discussed above is for comprising the voltage stabilizing circuit of recommending switch 15 and driver 20, yet the feature of variable turn-off time of the present invention also can be used on other pressurizer.For example, Fig. 3 and 4 and other adopt single voltage stabilizing circuits that trigger generators also can use this function, so that a stable voltage to be provided.
Fig. 7 is a detailed switching regulator circuit diagram, by variable turn-off time of the present invention and efficient control circuit, carrys out driving switch, comprises the MOSFET of a pair of synchronous switching.
When load current transships, for example surpass 20% of maximum output current, loop works is under continuous mode, and at this moment comparator 74 does not cover single output 245A that triggers generator 245.Along with V
iN-V
oUTbe greater than 1.5V, the operation of describing in the operation of this circuit and Fig. 1 is similar substantially.Electric current in inductance is by resistance R
sENSEthe pressure drop sensing at two ends, and the threshold value of current comparator 39 is determined by the pressure drop at resistance R 3 two ends.Built-in bias voltage V
oS(about 10mV) makes feedback voltage V
fBslightly lower than reference voltage V
rEFthereby the output 74 that makes comparator is high level under this pattern.Work as resistance R
sENSEthe voltage at two ends surpasses threshold value (resistance R
3pressure drop) time, the output of comparator 39 becomes high level, the RBAR input of rest-set flip-flop 310 becomes low level, reset rest-set flip-flop 310, thereby the shutoff cycle of starting switch.
In the shutoff cycle, switching signal V
sWBfor high level, this will make P channel mosfet 16 turn-off, and N-channel MOS FET17 is closed, and allows control capacitance C
cONelectric discharge.Turn-off time t
oFFby control capacitance C
cONfrom initial voltage V
tH1the Time dependent of electric discharge, this initial voltage is coupled to the non-inverting input of comparator 312.As control capacitance C
cONbe discharged to voltage V
tH1time, the output of comparator 312 becomes low level, thereby rest-set flip-flop 310 is set and starts the next closed cycle.Voltage V
tH1higher than voltage V
tH2thereby, make the output of comparator 315 keep low level under continuous mode.
According to this example, the turn-off time is controlled by variable turn-off time control circuit 250.Therefore, circuit 250 comprises input 252 and 254, and they are coupled to respectively V
iNand V
oUT, to monitor these voltage.
Current source I
1for current comparator 39 is provided with a minimum voltage threshold, i.e. the pressure drop at resistance R 3 two ends.This demand according to inductance L 1 is provided with a minimum current, and in each closed cycle trigger comparator 39.If flow to the average inductor current of output, be greater than load current, output voltage V
oUTto start increases, and causes feedback voltage V
fBtrigger hysteresis comparator 74.Certainly, the inductance value of inductance L 1 and turn-off time t
oFFall specially selected, while making to trigger, the ripple current of inductance is not less than zero.When comparator 74 triggers, its output becomes low level and covers the output Q of rest-set flip-flop 310, and the while is diverter switch signal V immediately
sWBfor high level.As discussed above, this sleep pattern of start-up operation automatically.
Under sleep pattern, capacitor C
cONelectric discharge as before, but comparator 312 does not start a new closed circulation while triggering.As discussed above, this is because until feedback voltage V
fBthe amount that decline comparator 74 lags behind, the low level force switch signal V of output 74A
sWBby NAND gate 316, keep high level.Therefore, control capacitance C
cONcontinue to be discharged to V
tH2below, thus cause the output 315A of comparator 315 to become high level.This causes again N-channel MOS FET17 to turn-off as P channel mosfet 16 conversely.When voltage regulator circuit is during in sleep pattern, the circuit element of not working, for example amplifier 38, comparator 39 and 312 are turned off.As discussed above, this can, at the sleep pattern Low-bias Current that declines, further raise the efficiency under low output current.
Under the turn-off time of sleep pattern expansion, many pressurizers and two MOSFET16 and 17 are turned off, and output loading is by output capacitance V
oUTpower supply.Yet, work as output voltage V
oUTwhile declining a feedback voltage, V
oUTthe hysteresis declining in a comparator 74, all circuit elements are turned on again, a new closed cycle, thus be output supply electric current.If load current is still very low, output capacitance V
oUTto charge, feedback voltage V
fBafter several switch periods, incite somebody to action trigger comparator 74 again.Therefore, under light load condition, output voltage V
oUTto between bound threshold value, shake, as discussed above.
When P channel mosfet 16 is closed, its grid-source voltage is the grid-source voltage of MOSFET334, and at this moment MOSFET334 is closed.This will draw high the drain voltage of MOSFET334, and suppresses N raceway groove driver 27.Along with V
sWBtransition from low to high, the voltage on P channel mosfet 16 grids must rise to certain level, and at this moment MOSFET334 produces the electric current that is less than current source 335 before the drain voltage of MOSFET334 declines, and allows N-channel MOS FET17 conducting.Electric current I
m1controlled make less, so the grid of MOSFET334 must rise to and input voltage V before driver is activated
iNdiffer and be less than 2 volts, P channel mosfet disconnects completely when guaranteeing that N-channel MOS FET17 is closed.Similarly, MOSFET332 and current source I
m2333 FET17 of N-channel MOS while guaranteeing that P channel mosfet 16 is closed turn-off completely.This can prevent their simultaneously conductings, no matter and the size of actuating speed or MOSFET, thereby guarantee to obtain the efficiency of maximum possible.
Schottky diode D2 in Fig. 7 and N-channel MOS FET coupling, only conducting in the Dead Time between MOSFET16 and 17.The object of diode D2 is the conducting store electric charge in Dead Time of body diode in order to prevent N-channel MOS FET17, and this body diode may lower efficiency in some cases (approximately 1%).Diode D2 is preferably in maximum output current when forward voltage is less than 0.5 volt.
According to the present invention, when the control circuit in Fig. 7 is included the synchronous buck type switching regulator of 5 volts in, for example, within surpassing two orders of magnitude (20mA changes to 2A), output current can realize the efficiency (input voltages of approximately 10 volts) that surpasses 90%.Under some condition of work, (for example input voltage is 6 volts) can keep more than 95% efficiency under such levels of current.Such control circuit is specially adapted to notebook computer, palmtop computer, portable instrument, battery powered digital device, cell phone, direct current power compartment system and gps system.
According to the above-mentioned discussion about Fig. 1, a shortcoming of control circuit 10 is, when low output current, if at t
oFFelectric current declines too much during this time, and polarity inversion may occur the electric current in inductance L 1.This may cause power from load, to be pulled to ground connection by N-channel MOS FET17, and the efficiency of circuit can reduce simultaneously.According to another feature of the present invention, above-mentioned control circuit can comprise that one for disconnecting the circuit of N-channel MOS FET, prevents above-mentioned shortcoming when the polarity inversion of inductive current.
Fig. 8 is a switching regulator circuit diagram, prevents the polarity inversion of electric current in outputting inductance by a circuit of the present invention.
Similar to Fig. 1, switching regulaor 400 comprises: recommend switch 15, drive circuit 20 and output circuit 30.Circuit 400 also comprises an efficient example 470 of controlling of the present invention, and it is for preventing the polarity inversion of outputting inductance L1 electric current.
Similar to Fig. 1, control circuit 470 comprises single-shot trigger circuit 25, current comparator 39 and trsanscondutance amplifier 38.Except these elements, control circuit 470 also comprises comparator 471 and door 472, for preventing under harmonic(-)mean levels of current, and inductive current generation polarity inversion and from load draw power.The operation principle of control circuit 470 is as follows.
When the output 25A of single-shot trigger circuit becomes high level so that P channel mosfet 16 turn-offs and N-channel MOS FET17 is closed, inductive current I
lstart sharply to decline.Under harmonic(-)mean output current, this electric current may drop to zero also finally may become negative value.Control circuit 470 is by current feedback signal I
fB2monitoring inductive current I
l, and before there is current reversal, N-channel MOS FET17 is turn-offed.This can prevent that N-channel MOS FET17 is from load draw power.
N-channel MOS FET17 closes and has no progeny, as feedback current I
fB2surpass electric current I
4and the output 471c that causes comparator is while becoming high level, it can be closed again.Generally, the output 471c of comparator will again become high level when single-shot trigger circuit 25 is closed by P channel mosfet 16, and this causes again inductive current I conversely
lagain rise.The rising of this electric current will allow current feedback signal I
fB2surpass I
4, therefore, cause the output 471c of comparator to become high level.When comparator 471c is output as high level, single-shot trigger circuit 25 is controlled separately the conducting of N-channel MOS FET17.
Therefore, control circuit 470 is included in the circuit during current reversal, N-channel MOS FET17 being turn-offed, otherwise the reversion of electric current will cause it from load draw power.This feature of the present invention can be under lower average output current level (at this moment most probable generation current reversal phenomenon) improve the efficiency of circuit.
Obviously, although comparator 471 passes through feedback current I
fB2monitoring inductive current I
l, other prevent inductive current I
lthe circuit taking a turn for the worse also can be used.For example, comparator 471 also can monitoring current feedback signal I
fB1so, only have the current feedback signal of a type to be loaded into control circuit 470.In addition, other can be according to inductive current I
lthe reversion circuit that produces feedback signal also can be used (the resistance R in Fig. 7 for example
sENSE).
Fig. 1-8 that efficient control circuit according to the present invention obtains have been discussed above, and they are characterised in that switching regulator has adopted voltage drop configuration.Obviously, other configuration also can be used for control circuit of the present invention.For example, Fig. 9 is a switching regulator circuit diagram, and by boosting, the efficient control circuit configuring carrys out driving switch.
As shown in Figure 9, control circuit of the present invention can configure for switch, wherein input voltage V
iNhigher than stable output voltage V
oUT.The same with the buck configuration in Fig. 2-8, control circuit also can use the configuration of boosting shown in Fig. 9.For example, the single-shot trigger circuit in Fig. 9 25 can comprise that an additional input is for monitoring input voltage V
iNthereby, when low input, reduce the noise in inductance L 1.In addition, switching regulaor 500 can comprise the circuit for keeping P channel mosfet 16 to turn-off, and is similar to Fig. 8, and this can prevent inductive current I
lpolarity inversion.
Figure 10 is a switching regulator circuit diagram, and the efficient control circuit configuring by polarity inversion of the present invention carrys out driving switch.
The operation of control circuit 70' is all similar to control circuit 70 discussed above substantially except to be discussed below.The feedback voltage of control circuit 70' is provided by resistance R 1, R2 and amplifier 602.Amplifier 602 is reversed in V
oUTthe reverse voltage at place, thus the feedback voltage of positive polarity provided for control circuit 70'.
As shown in Figure 10, control circuit of the present invention can configure for switch, one of them input voltage V
iNbe reversed to a stable opposite polarity output voltage V
oUT.The same with the buck configuration of Fig. 2-8, the control circuit in Figure 10 also can be used the polar configurations of other types.For example, the single-shot trigger circuit in Figure 10 25 can comprise that an additional input is for monitoring input voltage V
iN, to reduce generation and the discharge of inductance L 1 noise when the low input.In addition, single-shot trigger circuit 25 can comprise that one for monitoring output voltage V
oUTinput, when output short-circuit, control short circuit current.In addition, if pressurizer 600 is synchronously switched, and replace D601 with a N-channel MOS FET, adjuster can be included in inductive current I
lthe circuit that keeps this N-channel MOS FET to turn-off during polarity inversion, as above regarding to, Fig. 8 discusses.
Although the present invention embodies by concrete example, above-mentioned example just should not limit the present invention for the present invention is described.It should be pointed out that as long as no departing from essence of the present invention and meeting the definition in claim, on above-mentioned example, make suitable modification and still belong to category of the present invention.
For example, the present invention embodies by Fig. 1-10 discussed above, wherein mains switch is that the MOSFET(of a pair of complementation is a p raceway groove and a n raceway groove) or a single p channel mosfet (as shown in Figure 3), the present invention also can use the switch of other types.For example, mains switch can be a pair of N-channel MOS FET, a pair of P channel mosfet or bipolar transistor.
Claims (7)
1. a switch voltage-stabilizing circuit, it is characterized in that: control circuit is controlled a regulator, under a stable voltage, to load, supply with electric current, above-mentioned adjuster comprise one for receiving the switching circuit of input voltage, switching transistor, diode, inductance element, comprise the output circuit of an output capacitance, above-mentioned control circuit comprises: an error amplifier, and its input is coupled to reference edge and above-mentioned output circuit; A current comparator circuit, its input is coupled to an output of above-mentioned error amplifier and the current feedback signal of an inductance element; A bias source is coupled to an input of above-mentioned current comparator circuit, above-mentioned bias source is that current comparator circuit arranges a minimum feedback current threshold, this minimum feedback current threshold has determined that a minimum current is to trigger above-mentioned current comparator, and the value of this minimum current is determined by above-mentioned switching transistor and inductance element; First input of a hysteresis comparator is coupled to reference edge, and second input is coupled to above-mentioned output circuit and an output, and when the first and second inputs compare in a predetermined manner, above-mentioned output is changed into the second state from the first state; A logical circuit is coupled between above-mentioned hysteresis comparator and switching transistor, and when the output of hysteresis comparator is above-mentioned the second state, logical circuit prevents above-mentioned switching transistor conducting.
2. a kind of switch voltage-stabilizing circuit according to claim 1, it is characterized in that: a bucking voltage is based upon between the input of above-mentioned error amplifier and the input of hysteresis comparator, and this bucking voltage suppresses the variation of above-mentioned hysteresis comparator output state when high load currents.
3. a kind of switch voltage-stabilizing circuit according to claim 1, is characterized in that: above-mentioned current comparator is coupled to a monostable circuit, and an output of this monostable circuit is coupled to above-mentioned logical circuit.
4. a kind of switch voltage-stabilizing circuit according to claim 1, it is characterized in that: an amplifier circuit is coupling between above-mentioned output circuit and the input of error amplifier, to provide positive feedback in a regulator circuit, wherein the input voltage of regulator circuit and the voltage of load place have contrary polarity.
5. a kind of switch voltage-stabilizing circuit according to claim 1, it is characterized in that: control circuit is supplied with electric current to load for controlling a switching regulator under a stable voltage, above-mentioned adjuster has switching circuit to be suitable for receiving input voltage, and comprise a switching transistor, a diode, an inductance element, output circuit comprises an output capacitance, control procedure comprises the following steps: (a) monitoring is by the electric current of inductance element, to produce the first feedback signal; (b) output voltage of monitoring pressurizer, to produce the second feedback signal; (c) produce a minimum current threshold value; (d) according to the second feedback signal, produce a current threshold, this current threshold is maintained at or higher than minimum current threshold value; (e) according to the size of the first feedback signal and above-mentioned current threshold, produce the first control signal, to turn on and off transistor; (f) size that surpasses threshold voltage according to the second feedback signal produces the second control signal, second control signal gating the first control signal is connected regardless of the first control signal to prevent transistor, thereby make this transistor be held to turn-off, output current is supplied with by output capacitance.
6. a kind of switch voltage-stabilizing circuit according to claim 5, is characterized in that: the current threshold that above-mentioned steps (d) produces is greater than minimum current threshold value, and and the second feedback signal and a constant voltage between voltage difference roughly proportional.
7. a kind of switch voltage-stabilizing circuit according to claim 5, is characterized in that: above-mentioned the first control signal was turn-offed transistor with cycle predetermined time.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310612898.3A CN103618453A (en) | 2013-11-27 | 2013-11-27 | Switching regulator circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310612898.3A CN103618453A (en) | 2013-11-27 | 2013-11-27 | Switching regulator circuit |
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|---|---|
| CN103618453A true CN103618453A (en) | 2014-03-05 |
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|---|---|---|---|
| CN201310612898.3A Pending CN103618453A (en) | 2013-11-27 | 2013-11-27 | Switching regulator circuit |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108075662A (en) * | 2016-11-16 | 2018-05-25 | 三星电子株式会社 | The equipment of semiconductor device and overcurrent protection |
| CN108512530A (en) * | 2017-02-24 | 2018-09-07 | 意法半导体股份有限公司 | Drive circuit, corresponding ultrasonic unit and method |
| CN108880242A (en) * | 2017-05-10 | 2018-11-23 | 力智电子股份有限公司 | DC-DC controller and control method thereof |
| CN110618378A (en) * | 2018-06-20 | 2019-12-27 | 皮尔茨有限及两合公司 | Circuit arrangement for switching an electrical load and method for checking the state of a safety output of a circuit arrangement |
| CN112564479A (en) * | 2016-11-18 | 2021-03-26 | 华为技术有限公司 | Voltage regulating circuit and voltage regulating method |
| CN113867462A (en) * | 2021-09-30 | 2021-12-31 | 深圳安吉尔饮水产业集团有限公司 | Current source circuit |
| WO2022178856A1 (en) * | 2021-02-26 | 2022-09-01 | 华为技术有限公司 | Charging circuit and electronic device |
| CN106411301B (en) * | 2016-11-11 | 2024-04-19 | 国网山东省电力公司临邑县供电公司 | High-low level mixed effective switch reset circuit |
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| CN203562957U (en) * | 2013-11-27 | 2014-04-23 | 苏州贝克微电子有限公司 | Switching voltage regulator circuit |
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| US5481178A (en) * | 1993-03-23 | 1996-01-02 | Linear Technology Corporation | Control circuit and method for maintaining high efficiency over broad current ranges in a switching regulator circuit |
| CN203562957U (en) * | 2013-11-27 | 2014-04-23 | 苏州贝克微电子有限公司 | Switching voltage regulator circuit |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106411301B (en) * | 2016-11-11 | 2024-04-19 | 国网山东省电力公司临邑县供电公司 | High-low level mixed effective switch reset circuit |
| CN108075662A (en) * | 2016-11-16 | 2018-05-25 | 三星电子株式会社 | The equipment of semiconductor device and overcurrent protection |
| CN108075662B (en) * | 2016-11-16 | 2021-12-28 | 三星电子株式会社 | Semiconductor device and overcurrent protection apparatus |
| CN112564479A (en) * | 2016-11-18 | 2021-03-26 | 华为技术有限公司 | Voltage regulating circuit and voltage regulating method |
| CN108512530A (en) * | 2017-02-24 | 2018-09-07 | 意法半导体股份有限公司 | Drive circuit, corresponding ultrasonic unit and method |
| CN108512530B (en) * | 2017-02-24 | 2022-08-19 | 意法半导体股份有限公司 | Driver circuit, corresponding ultrasonic device and method |
| CN108880242A (en) * | 2017-05-10 | 2018-11-23 | 力智电子股份有限公司 | DC-DC controller and control method thereof |
| CN108880242B (en) * | 2017-05-10 | 2021-04-13 | 力智电子股份有限公司 | DC-DC controller and control method thereof |
| CN110618378A (en) * | 2018-06-20 | 2019-12-27 | 皮尔茨有限及两合公司 | Circuit arrangement for switching an electrical load and method for checking the state of a safety output of a circuit arrangement |
| WO2022178856A1 (en) * | 2021-02-26 | 2022-09-01 | 华为技术有限公司 | Charging circuit and electronic device |
| CN113867462A (en) * | 2021-09-30 | 2021-12-31 | 深圳安吉尔饮水产业集团有限公司 | Current source circuit |
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Application publication date: 20140305 |