CN205051577U - Voltage boosting circuit - Google Patents

Abstract

The utility model provides a boost circuit, boost circuit adopts the switch in the fixed time long switch-on circuit control boost circuit. The booster circuit comprises an input port, an output port, an inductor, a pull-up switch, a pull-down switch and a control circuit. In each switching period, the control circuit controls the pull-down switch to be conducted for a fixed duration. The utility model provides a boost circuit simple structure, the system bandwidth is higher, therefore has better transient characteristic. And simultaneously, the utility model provides a boost circuit has fixed switching frequency under the input voltage and the output voltage condition of difference to have higher circuit efficiency under the light load condition.

Description

A kind of booster circuit

Technical field

The utility model relates to a kind of electronic circuit, and more particularly, the utility model relates to a kind of switching circuit.

Background technology

Traditional booster circuit (BOOST) adopts Peak Current-Mode Controlled Circuit usually.In the booster circuit of peak value comparison method, for ensureing the stable of Circuits System, system bandwidth is lower, and namely transient response is slower.

Therefore, have and need to propose a kind of circuit structure simply, system bandwidth is higher, and has higher circuit efficiency booster circuit simultaneously.

Utility model content

Consider one or more technical problems of prior art, propose a kind of booster circuit.

According to the embodiment of this technology, propose a kind of booster circuit with fixed switching frequency, comprising: input port, receive input voltage; Output port, provides output voltage; Inductance, has first end and the second end, and described first end receives input voltage; Upper drag switch, has first end, the second end and control end, and described first end is coupled to the second end of inductance, and described second end couples output port, and described control end receives pull-up control signal; Pull down switch, have first end, the second end and control end, described first end is coupled to the second end of inductance, described second end ground connection, and described control end receives drop-down control signal; And control circuit, there is first input end, the second input, the first output and the second output, wherein said first input end receives the feedback signal characterizing output voltage, described second input receives reference signal, described first output exports drop-down control signal, second output exports pull-up control signal, wherein, when input voltage and output voltage are fixed, in each switch periods, described in pull down switch conducting one section of fixing duration under the control of drop-down control signal.

In one embodiment, described control circuit also comprises the 3rd input, described 3rd input receives the current detection signal that sign flows through the electric current of drag switch, the drop-down control signal that the pull-up control signal of the upper drag switch of described control circuit output control and control pull down switch.

In one embodiment, described control circuit comprises: feedback amplifier, has first input end, the second input and output, and described first input end receives reference signal, described second input receiving feedback signals, described feedback amplifier is at output output voltage control signal; Feedback comparator, there is first input end, the second input and output, described first input end receives the current detection signal characterizing and flow through the electric current of drag switch, described second input is coupled to the output receiver voltage control signal of feedback amplifier, and described output exports conductivity control signal; Conducting duration control circuit, have first input end, the second input, the 3rd input and output, described first input end receives input voltage, and described second input receives output voltage, described 3rd input receives drop-down control signal, and described output exports and turns off control signal; And logical circuit, there is first input end, the second input, the first output and the second output, the output that described first input end is coupled to feedback comparator receives conductivity control signal, the output that described second input is coupled to conducting duration control circuit receives shutoff control signal, described first output exports drop-down control signal, and the second output exports pull-up control signal.

According to the embodiment of this technology, also proposed a kind of control circuit with the booster circuit of fixed switching frequency, described booster circuit comprises drag switch, pulls down switch and inductance, it is characterized in that, described control circuit comprises: feedback amplifier, has first input end, the second input and output, and described first input end receives reference signal, described second input receives the feedback signal of the output voltage characterizing booster circuit, described output output voltage control signal; Feedback comparator, there is first input end, the second input and output, described first input end receives the current detection signal characterizing and flow through the electric current of drag switch, described second input is coupled to the output receiver voltage control signal of feedback amplifier, and described output exports conductivity control signal; Conducting duration control circuit, has input and output, and described input receives drop-down control signal, and described output exports and turns off control signal; And logical circuit, there is first input end, the second input, the first output and the second output, the output that described first input end is coupled to feedback comparator receives conductivity control signal, the output that described second input is coupled to conducting duration control circuit receives shutoff control signal, described first output exports drop-down control signal, and the second output exports pull-up control signal; Wherein, when input voltage and output voltage are fixing, in each switch periods, described in pull down switch conducting one section of fixing duration under the control of drop-down control signal.

In one embodiment, described conducting duration control circuit comprises: controllable current source circuit, there is input, output and control end, described input reception control circuit supply voltage, described control end receives output voltage, and described output exports and the directly proportional variable current of output voltage; Electric capacity, have first end and the second end, described first end is coupled in the output of controllable current source circuit, described second end ground connection, receives the electric current that controllable current source circuit exports; First switch, have first end, the second end and control end, described first end is coupled to the first end of electric capacity, described second end ground connection, and described control end receives drop-down control signal; Controllable voltage source circuit, there is first end, second end, the first control end and the second control end, described second end ground connection, described first control end receives input voltage, described second control end receives output voltage, and described first end exports the directly proportional controllable voltage signal of difference with output voltage and input voltage; And shutoff comparator, have first input end, the second input and output, described first input end is coupled to the first end of electric capacity, and described second input is coupled to the first end of controllable voltage source circuit, and described output exports and turns off control signal.

In one embodiment, described controllable current source circuit comprises: the first resistance, has first end and the second end, described second end ground connection; Second switch, have first end, the second end and control end, described second end is coupled to the first end of the first resistance; First error amplifier, there is first input end, the second input and output, described first input end receives the voltage signal proportional with output voltage, and described second input is coupled to the tie point of the first resistance and second switch, and described output is coupled to the control end of second switch; And first current mirroring circuit, have power end, first end and the second end, described power end reception control circuit supply voltage, described first end is coupled to the first end of second switch, and described second end exports and the directly proportional variable current of output voltage.

In one embodiment, described controllable voltage source circuit comprises: the second resistance, has first end and the second end, described second end ground connection; Second current mirroring circuit, has power end, first end and the second end, and described power end receives input voltage, and described first end is coupled to the first end of the second resistance; 3rd current mirroring circuit, has power end, first end and the second end, described power end ground connection, and described first end is coupled to second end on the second current mirror road; 3rd resistance, has first end and the second end, and described first end is coupled to the second end of the 3rd current mirroring circuit, described second end ground connection; 4th current mirroring circuit, has power end, first end and the second end, and described power end receives output voltage, and described first end is coupled to the first end of the 3rd resistance; And the 4th resistance, have first end and the second end, described first end is coupled to the second end of the 4th current mirroring circuit, described second end ground connection; Wherein, described controllable voltage signal produces at the first end of the 3rd resistance.

In one embodiment, described controllable voltage source circuit comprises: the 5th resistance, has first end and the second end, and described first end receives output voltage; 3rd switch, has first end, the second end and control end, and described first end is coupled to the second end of the 5th resistance; 6th resistance, has first end and the second end, and described first end is coupled to the second end of the 3rd switch, described second end ground connection; 7th resistance, has first end and the second end, and described first end receives input voltage; And second error amplifier, there is first input end, the second input and output, described first input end is coupled to the second end of the 7th resistance, and described second input is coupled to the second end of the 5th resistance, and described output is coupled to the control end of the 3rd switch.

According to the booster circuit that the above-mentioned each side of the utility model provides, circuit structure is simple, and system bandwidth is high, and has higher circuit efficiency under underloading condition.

Accompanying drawing explanation

In order to better understand the utility model, will be described in detail the utility model according to the following drawings:

Fig. 1 shows the electrical block diagram of the booster circuit 10 according to the utility model one embodiment;

Fig. 2 shows the waveform schematic diagram of the part signal in the booster circuit 10 in Fig. 1;

Fig. 3 shows the electrical block diagram of the conducting duration control circuit 105 according to the utility model one embodiment;

Fig. 4 shows the electrical block diagram of the controllable current source circuit 301 according to the utility model one embodiment;

Fig. 5 shows the electrical block diagram of the controllable voltage source circuit 302 according to the utility model one embodiment;

Fig. 6 shows the electrical block diagram of the variable voltage source circuit 302 according to another embodiment of the utility model;

Fig. 7 shows the schematic flow sheet of the control method 70 of the booster circuit according to the utility model one embodiment.

Embodiment

To specific embodiment of the utility model be described in detail below, it should be noted that the embodiments described herein is only for illustrating, is not limited to the utility model.In the following description, in order to provide thorough understanding of the present utility model, a large amount of specific detail has been set forth.But, those of ordinary skill in the art be it is evident that: these specific detail need not be adopted to carry out the utility model.In other instances, in order to avoid obscuring the utility model, do not specifically describe known circuit, material or method.

In whole specification, " embodiment ", " embodiment ", " example " or mentioning of " example " are meaned: the special characteristic, structure or the characteristic that describe in conjunction with this embodiment or example are comprised at least one embodiment of the utility model.Therefore, the phrase " in one embodiment " occurred in each place of whole specification, " in an embodiment ", " example " or " example " differ to establish a capital and refer to same embodiment or example.In addition, can with any suitable combination and/or sub-portfolio by specific feature, structure or property combination in one or more embodiment or example.In addition, it should be understood by one skilled in the art that the accompanying drawing provided at this is all for illustrative purposes, and accompanying drawing is not necessarily drawn in proportion.Should be appreciated that when claim element " be connected to " or " being couple to " another element time, it can be directly connected or coupled to another element or can there is intermediary element.On the contrary, when claim element " be directly connected to " or " being directly coupled to " another element time, there is not intermediary element.Identical Reference numeral indicates identical element.Term "and/or" used herein comprises any and all combinations of one or more relevant project listed.

Fig. 1 shows the electrical block diagram of the booster circuit 10 according to the utility model one embodiment.As shown in Figure 1, booster circuit 10 comprises: input port 101, receives input voltage vin; Output port 102, provides output voltage Vout; Inductance L 1, have first end and the second end, described first end is coupled to input port 101 and receives input voltage vin; Upper drag switch HS, has first end, the second end and control end, and described first end is coupled to the second end of inductance L 1, and described second end couples output port 102, and described control end receives pull-up control signal HG; Pull down switch LS, has first end, the second end and control end, and described first end is coupled to the second end of inductance L 1, described second end ground connection, and described control end receives drop-down control signal LG; And control circuit 11, there is first input end, the second input, the first output and the second output, wherein said first input end receives the feedback signal Vfb characterizing output voltage Vout, described second input receives reference signal Vref, based on described feedback signal Vfb and reference signal Vref, described control circuit 11 exports pull-up control signal HG and drop-down control signal LG, wherein, in each switch periods, described drop-down control signal LG controls to pull down switch the fixing duration Ton of LS conducting one section.

In the embodiment shown in fig. 1, booster circuit 10 also comprises the electric capacity Cout be coupled between output 102 and ground.Further, the load of booster circuit 10 represents with resistance RL.

In one embodiment, described upper drag switch HS and the LS that pulls down switch comprises any controllable semiconductor switch, as metal oxide semiconductor field effect tube, bipolar transistor etc.

In one embodiment, control circuit 11 comprises: feedback amplifier 103, there is first input end (normal phase input end), the second input (negative-phase input) and output, described first input end receives reference signal Vref, described second input receiving feedback signals Vfb, based on described reference signal Vref and feedback signal Vfb, described feedback amplifier 103 is at output output voltage control signal Vcom; Feedback comparator 104, there is first input end (negative-phase input), the second input (normal phase input end) and output, described first input end receives the current detection signal Ics characterizing and flow through the electric current of drag switch HS, described second input is coupled to the output receiver voltage control signal Vcom of feedback amplifier 103, based on described current detection signal Ics and voltage control signal Vcom, described output exports conductivity control signal Ictr; Conducting duration control circuit 105, there is first input end, the second input, the 3rd input and output, described first input end receives input voltage vin, described second input receives output voltage Vout, described 3rd input receives drop-down control signal LG, based on described input voltage vin, output voltage Vout and drop-down control signal LG, described output exports and turns off control signal COT; And logical circuit 12, there is first input end, the second input, the first output and the second output, the output that described first input end is coupled to feedback comparator 104 receives conductivity control signal Ictr, the output that described second input is coupled to conducting duration control circuit 105 receives shutoff control signal COT, based on described conductivity control signal Ictr and shutoff control signal COT, described logical circuit 12 exports drop-down control signal LG at the first output, exports pull-up control signal HG at the second output.

In one embodiment, logical circuit 12 comprises: rest-set flip-flop 106, there is set end " S ", reset terminal " R " and output " Q ", the output that described set end " S " is coupled to feedback comparator 104 receives conductivity control signal Ictr, the output that described reset terminal " R " is coupled to conducting duration control circuit 105 receives shutoff control signal COT, based on conductivity control signal Ictr and shutoff control signal COT, described rest-set flip-flop 106 exports drop-down control signal LG at output " Q "; And inverter 107, there is input and output, the output " Q " that described input is coupled to rest-set flip-flop 106 receives drop-down control signal LG, and based on drop-down control signal LG, described inverter 107 exports the pull-up control signal HG contrary with drop-down control signal LG phase place at output.In one embodiment, described logical circuit also comprises dead zone function circuit.Turn off at upper drag switch HS, pull down switch LS conducting, or the LS that pulls down switch turns off, and the moment of upper drag switch HS conducting, on dead zone function control circui, drag switch HS and the LS that pulls down switch turns off one section of default Dead Time simultaneously.

Fig. 2 shows the waveform schematic diagram of the part signal in the booster circuit 10 in Fig. 1.The course of work of booster circuit 10 is described below in conjunction with Fig. 1 and Fig. 2.When booster circuit 10 is operated in stable state, in each switch periods, when upper drag switch HS conducting and pull down switch LS turn off time, flow through drag switch HS electric current decline, namely current detection signal Ics declines.When current detection signal Ics drops to the value of voltage control signal Vcom, comparator 104 overturns, export conductivity control signal Ictr set rest-set flip-flop 106, now, rest-set flip-flop 106 exports drop-down control signal LG turns on pull-down switch LS, simultaneously, inverter 107 exports drag switch HS in pull-up control signal HG shutoff, now, the electric current in inductance L 1 increases, and the electric current namely flowing through the LS that pulls down switch increases.After fixing conducting duration Ton, conducting duration control circuit 105 exports and turns off control signal COT with reset rest-set flip-flop 106, now, rest-set flip-flop 106 exports pull-up control signal HG and turns off the LS that pulls down switch, meanwhile, inverter 107 exports drag switch HS in pull-up control signal HG conducting, now, electric current in inductance L 1 reduces, and the electric current namely flowing through drag switch HS reduces.When current detection signal Ics drops to voltage control signal Vcom, feedback comparator 104 overturns, again set rest-set flip-flop 106, and the next switch periods of booster circuit 10 starts.

In the above description, described fixing conducting duration Ton is fixed as prerequisite with input voltage vin and output voltage Vout.That is, under different input voltage vin and output voltage Vout condition, conducting duration Ton is change.

Those of ordinary skill in the art it should be understood that under different input voltages, output voltage and loading condition, if the LS that pulls down switch fixes at the conducting duration of each switch periods, then the switching frequency of this booster circuit must be change.

In some application scenario, the switching frequency of booster circuit is required to fix.Therefore, the utility model proposes with input voltage and output voltage change and the conducting duration control circuit 105 of change.

Those of ordinary skill in the art it should be understood that the duty ratio of booster circuit is relevant with output voltage Vout to input voltage vin, and physical relationship is shown in following formula (1):

$DT=\frac{Ton}{T}=\frac{Vout-Vin}{Vout}---\left(1\right)$

Can be derived by formula (1) and obtain formula (2):

$Ton=T\×\frac{Vout-Vin}{Vout}---\left(2\right)$

From formula (2), be the switching frequency be fixed, namely fixing switch periods is looked T, and conducting duration Ton must be directly proportional to the difference of input voltage vin to output voltage Vout, and is inversely proportional to the value of output voltage Vout.

Fig. 3 shows the electrical block diagram of the conducting duration control circuit 105 according to the utility model one embodiment.As shown in Figure 3, conducting duration control circuit 105 comprises: controllable current source circuit 301, there is input, output and control end, described input reception control circuit power source voltage Vcc, described control end receives output voltage Vout, based on described control circuit power source voltage Vcc and output voltage Vout, described controllable current source circuit exports and the directly proportional variable current Ich of output voltage at output; Electric capacity C1, have first end and the second end, described first end is coupled in the output of controllable current source circuit 301, described second end ground connection, receives the electric current I ch that controllable current source circuit 301 exports; First switch M1, have first end, the second end and control end, described first end is coupled to the first end of electric capacity C1, described second end ground connection, and described control end receives drop-down control signal LG; Controllable voltage source circuit 302, there is first end, second end, the first control end and the second control end, described second end ground connection, described first control end receives input voltage vin, described second control end receives output voltage Vout, and based on described input voltage vin and output voltage Vout, described controllable voltage source circuit 302 exports the difference directly proportional controllable voltage signal Vch with output voltage Vout and input voltage vin at first end; And turn off comparator 303, there is first input end, the second input and output, described first input end is coupled to the first end of electric capacity, described second input is coupled to the first end of controllable voltage source circuit 302, based on the voltage signal Vc1 on electric capacity C1 and controllable voltage signal Vch, described shutoff comparator 303 exports at output and turns off control signal COT.

In the circuit of Fig. 3, the value of described variable current Ich is Ich=K1 × Vout, and the value of described variable voltage is Vch=K2 × (Vout-Vin).Wherein, K1 and K2 is fixed constant.When pull down switch LS conducting time, under the control of drop-down control signal LG, the first switch M1 turns off when pulling down switch LS conducting.Now, variable current Ich charges to electric capacity C1, and the voltage Vc1 on electric capacity C1 rises.After the value of the voltage Vc1 on electric capacity C1 reaches the value of variable voltage Vch, turn off control signal COT and export pulse, reset rest-set flip-flop 106, make rest-set flip-flop 106 export drop-down control signal LG and turn off the LS that pulls down switch.

As from the foregoing, the conducting duration Ton of LS of pulling down switch has following relation:

$Ton=\frac{C1\×Vch}{Ich}=C1\×\frac{K2\×(Vout-Vin)}{K1\×Vout}---\left(3\right)$

Capacitance due to electric capacity C1 is constant, and the value of conducting duration Ton is directly proportional to the difference Vout-Vin of output voltage and input voltage, and is inversely proportional to output voltage Vout.Therefore, when after the conducting duration control circuit 105 that booster circuit 10 adopts as shown in Figure 3, under the prerequisite that input voltage vin and output voltage Vout are fixed, the switching frequency of booster circuit 10 is fixed.

Fig. 4 shows the electrical block diagram of the controllable current source circuit 301 according to the utility model one embodiment.As shown in Figure 4, controllable current source circuit 301 comprises: the first resistance R1, has first end and the second end, described second end ground connection; Second switch M2, has first end, the second end and control end, and described second end is coupled to the first end of the first resistance R1; First error amplifier 401, there is first input end, the second input and output, described first input end receives the voltage signal Vr proportional with output voltage Vout, described second input is coupled to the tie point of the first resistance R1 and second switch M2, and described output is coupled to the control end of second switch M2; And first current mirroring circuit 402, there is power end, first end and the second end, described power end reception control circuit power source voltage Vcc, described first end is coupled to the first end of second switch M2, and described second end exports and the directly proportional variable current Ich of output voltage Vout.

Due to the characteristic of error amplifier, the magnitude of voltage approximately equal of its two input.Therefore, the voltage VR1 on the first resistance R1 equals voltage signal Vr, i.e. VR1=Vr=K3 × Vout, and wherein, K3 is fixed constant.Thus the electric current flowing through resistance R1 is IR1=VR1/R1=K3 × Vout/R1.Variable current Ich is the image current of the electric current flowing through R1.If the mirroring ratios of the first current mirroring circuit 402 is 1:K4, then the value of variable current is Ich=K4 × IR1=K3 × K4 × Vout/R1=K5 × Vout, K5=K3 × K4/R1, is fixed constant.

In one embodiment, described voltage signal Vr is obtained after divider resistance Rd1 and Rd2 dividing potential drop by output voltage Vout, namely

In one embodiment, described first current mirroring circuit 402 comprises P type MOSFET.

Fig. 5 shows the electrical block diagram of the controllable voltage source circuit 302 according to the utility model one embodiment.As shown in Figure 5, described controllable voltage source circuit 302 comprises: the second resistance R2, has first end and the second end, described second end ground connection; Second current mirroring circuit 501, has power end, first end and the second end, and described power end receives input voltage vin, and described first end is coupled to the first end of the second resistance R2; 3rd current mirroring circuit 502, has power end, first end and the second end, described power end ground connection, and described first end is coupled to the second end of the second current mirroring circuit 501; 3rd resistance R3, has first end and the second end, and described first end is coupled to the second end of the 3rd current mirroring circuit 502, described second end ground connection; 4th current mirroring circuit 503, has power end, first end and the second end, and described power end receives output voltage Vout, and described first end is coupled to the first end of the 3rd resistance R3; And the 4th resistance R4, have first end and the second end, described first end is coupled to the second end of the 4th current mirroring circuit 503, described second end ground connection; Wherein, described controllable voltage signal Vch produces at the first end of the 3rd resistance R3.

Those of ordinary skill in the art it should be understood that the voltage that current mirroring circuit consumes can be ignored.The value of the electric current I 1 therefore the second resistance R2 flow through is I1=Vin/R2.In like manner, the value of the electric current I 4 the 4th resistance R4 flow through is I4=Vout/R4.Suppose that the mirroring ratios of the second current mirror 501 and the 4th current mirror 503 is 1:1, so the value of electric current I 2 is I2=I1, and the value of electric current I 3 is I3=I4.Suppose that the mirroring ratios of the 3rd current mirror 502 is also 1:1, to be then IR3 be the electric current flowing through resistance R3 that value is IR3=I3-I2.Thus value Vch=(I3-I2) × R3=(the Vout/R4-Vin/R2) × R3 of variable voltage Vch can be obtained.If R2=R4=Requ, then $Vch=\frac{R3}{\mathrm{Re}qu}\×(Vout-Vin)=K6\×(Vout-Vin),$ Wherein K6=R3/Requ, namely the value of variable voltage Vch is directly proportional to the difference Vout-Vin of output voltage and input voltage.

Fig. 6 shows the electrical block diagram of the variable voltage source circuit 302 according to another embodiment of the utility model.As shown in Figure 6, described variable voltage source circuit 302 comprises: the 5th resistance R5, has first end and the second end, and described first end receives output voltage Vout; 3rd switch M3, has first end, the second end and control end, and described first end is coupled to second end of the 5th resistance R5; 6th resistance R6, has first end and the second end, and described first end is coupled to second end of the 3rd switch M3, described second end ground connection; 7th resistance R7, has first end and the second end, and described first end receives input voltage vin; And second error amplifier 601, there is first input end, the second input and output, described first input end is coupled to second end of the 7th resistance R7, and described second input is coupled to second end of the 5th resistance R5, and described output is coupled to the control end of the 3rd switch M3.

The voltage approximately equal of Fig. 6 medial error amplifier 601 liang of inputs, therefore, electric current I R5=(Vout-Vin)/R5 that resistance R5 flows through.Thus, the value of variable voltage Vch is Vch=(Vout-Vin) × R6/R5=K7 × (Vout-Vin), i.e. the value of variable voltage Vch and the difference Vout-Vin direct proportionality of output voltage and input voltage, wherein, K7=R6/R5 is fixed constant.

Fig. 7 shows the schematic flow sheet of the control method 70 of the booster circuit according to the utility model one embodiment.Described booster circuit converts input voltage to output voltage, described booster circuit comprises inductance, is coupled in the upper drag switch between inductance and output voltage and is coupled in pulling down switch between inductance and ground, it is characterized in that, described control method 70 comprises: step 701, amplify the error between reference signal and the feedback signal characterizing output voltage, obtain voltage control signal; Step 702, comparative voltage control signal flows through the current detection signal of the electric current of drag switch with characterizing, obtain conductivity control signal; Step 703, generates drop-down control signal based on conductivity control signal and shutoff control signal; Step 704, generates based on drop-down control signal, input voltage and output voltage and turns off control signal; Step 705, anti-phase drop-down control signal is to generate pull-up control signal; And step 706, control upper drag switch by pull-up control signal, control to pull down switch by drop-down control signal, wherein, under the prerequisite that input voltage and output voltage are fixing, described in pull down switch under the control of drop-down control signal, the duration that conducting is fixing in each switch periods.

In one embodiment, described control method 70 also comprises the voltage generation current detection signal by sampling pull-up switch ends.

In one embodiment, step 704 comprises: generate the variable current with output voltage direct proportionality;

The variable voltage signal of the difference direct proportionality of generation and output voltage and input voltage;

Rise in the moment of drop-down control signal turns on pull-down switch, adopt described variable current to capacitor charging;

Turn off in drop-down control signal the moment pulled down switch to rise, to capacitor discharge; And

Comparison based on the voltage signal in variable voltage signal and electric capacity generates and turns off control signal.

The booster circuit that the utility model provides is higher owing to not possessing current loop, thus system bandwidth, has good transient response.Meanwhile, the booster circuit that the utility model provides has fixing switching frequency under different input voltages and output voltage condition, and has higher circuit efficiency under underloading condition.

Although exemplary embodiment describe the utility model with reference to several, should be appreciated that term used illustrates and exemplary and nonrestrictive term.Specifically can implement in a variety of forms due to the utility model and not depart from spirit or the essence of utility model, so be to be understood that, above-described embodiment is not limited to any aforesaid details, and explain widely in the spirit and scope that should limit in claim of enclosing, therefore fall into whole change in claim or its equivalent scope and remodeling and all should be claim of enclosing and contained.

Claims (12)

1. there is a booster circuit for fixed switching frequency, it is characterized in that, comprising:

Input port, receives input voltage;

Output port, provides output voltage;

Inductance, has first end and the second end, and described first end receives input voltage;

Upper drag switch, has first end, the second end and control end, and described first end is coupled to the second end of inductance, and described second end couples output port, and described control end receives pull-up control signal;

Pull down switch, have first end, the second end and control end, described first end is coupled to the second end of inductance, described second end ground connection, and described control end receives drop-down control signal; And

Control circuit, there is first input end, the second input, the first output and the second output, wherein said first input end receives the feedback signal characterizing output voltage, described second input receives reference signal, and described first output exports drop-down control signal, and the second output exports pull-up control signal, wherein, when input voltage and output voltage are fixing, in each switch periods, described in pull down switch conducting one section of fixing duration under the control of drop-down control signal.

2. there is the booster circuit of fixed switching frequency as claimed in claim 1, it is characterized in that, described control circuit also comprises the 3rd input, described 3rd input receives the current detection signal characterizing and flow through the electric current of drag switch, and described control circuit exports pull-up control signal and drop-down control signal controls drag switch respectively and pulls down switch.

3. have the booster circuit of fixed switching frequency as claimed in claim 1, it is characterized in that, described control circuit comprises:

Feedback amplifier, has first input end, the second input and output, and described first input end receives reference signal, described second input receiving feedback signals, and described feedback amplifier is at output output voltage control signal;

Feedback comparator, there is first input end, the second input and output, described first input end receives the current detection signal characterizing and flow through the electric current of drag switch, described second input is coupled to the output receiver voltage control signal of feedback amplifier, and described output exports conductivity control signal;

Conducting duration control circuit, have first input end, the second input, the 3rd input and output, described first input end receives input voltage, and described second input receives output voltage, described 3rd input receives drop-down control signal, and described output exports and turns off control signal; And

Logical circuit, there is first input end, the second input, the first output and the second output, the output that described first input end is coupled to feedback comparator receives conductivity control signal, the output that described second input is coupled to conducting duration control circuit receives shutoff control signal, described first output exports drop-down control signal, and the second output exports pull-up control signal.

4. have the booster circuit of fixed switching frequency as claimed in claim 3, it is characterized in that, described conducting duration control circuit comprises:

Controllable current source circuit, has input, output and control end, described input reception control circuit supply voltage, and described control end receives output voltage, and described output exports and the directly proportional variable current of output voltage;

Electric capacity, have first end and the second end, described first end is coupled in the output of controllable current source circuit, described second end ground connection, receives the electric current that controllable current source circuit exports;

First switch, have first end, the second end and control end, described first end is coupled to the first end of electric capacity, described second end ground connection, and described control end receives drop-down control signal;

Controllable voltage source circuit, there is first end, second end, the first control end and the second control end, described second end ground connection, described first control end receives input voltage, described second control end receives output voltage, and described first end exports the directly proportional controllable voltage signal of difference with output voltage and input voltage; And

Turn off comparator, have first input end, the second input and output, described first input end is coupled to the first end of electric capacity, and described second input is coupled to the first end of controllable voltage source circuit, and described output exports and turns off control signal.

5. have the booster circuit of fixed switching frequency as claimed in claim 4, it is characterized in that, described controllable current source circuit comprises:

First resistance, has first end and the second end, described second end ground connection;

Second switch, have first end, the second end and control end, described second end is coupled to the first end of the first resistance;

First error amplifier, there is first input end, the second input and output, described first input end receives the voltage signal proportional with output voltage, and described second input is coupled to the tie point of the first resistance and second switch, and described output is coupled to the control end of second switch; And

First current mirroring circuit, has power end, first end and the second end, described power end reception control circuit supply voltage, and described first end is coupled to the first end of second switch, and described second end exports and the directly proportional variable current of output voltage.

6. have the booster circuit of fixed switching frequency as claimed in claim 4, it is characterized in that, described controllable voltage source circuit comprises:

Second resistance, has first end and the second end, described second end ground connection;

Second current mirroring circuit, has power end, first end and the second end, and described power end receives input voltage, and described first end is coupled to the first end of the second resistance;

3rd current mirroring circuit, has power end, first end and the second end, described power end ground connection, and described first end is coupled to the second end of the second current mirroring circuit;

3rd resistance, has first end and the second end, and described first end is coupled to the second end of the 3rd current mirroring circuit, described second end ground connection;

4th current mirroring circuit, has power end, first end and the second end, and described power end receives output voltage, and described first end is coupled to the first end of the 3rd resistance; And

4th resistance, has first end and the second end, and described first end is coupled to the second end of the 4th current mirroring circuit, described second end ground connection;

Wherein, described controllable voltage signal produces at the first end of the 3rd resistance.

7. have the booster circuit of fixed switching frequency as claimed in claim 4, it is characterized in that, described controllable voltage source circuit comprises:

5th resistance, has first end and the second end, and described first end receives output voltage;

3rd switch, has first end, the second end and control end, and described first end is coupled to the second end of the 5th resistance;

6th resistance, has first end and the second end, and described first end is coupled to the second end of the 3rd switch, described second end ground connection;

7th resistance, has first end and the second end, and described first end receives input voltage; And

Second error amplifier, has first input end, the second input and output, and described first input end is coupled to the second end of the 7th resistance, and described second input is coupled to the second end of the 5th resistance, and described output is coupled to the control end of the 3rd switch.

8. have a control circuit for the booster circuit of fixed switching frequency, described booster circuit comprises drag switch, pulls down switch and inductance, it is characterized in that, described control circuit comprises:

Feedback amplifier, has first input end, the second input and output, and described first input end receives reference signal, and described second input receives the feedback signal of the output voltage characterizing booster circuit, described output output voltage control signal;

Feedback comparator, there is first input end, the second input and output, described first input end receives the current detection signal characterizing and flow through the electric current of drag switch, described second input is coupled to the output receiver voltage control signal of feedback amplifier, and described output exports conductivity control signal;

Conducting duration control circuit, has input and output, and described input receives drop-down control signal, and described output exports and turns off control signal; And

Logical circuit, there is first input end, the second input, the first output and the second output, the output that described first input end is coupled to feedback comparator receives conductivity control signal, the output that described second input is coupled to conducting duration control circuit receives shutoff control signal, described first output exports drop-down control signal, and the second output exports pull-up control signal;

Wherein, when input voltage and output voltage are fixing, in each switch periods, described in pull down switch conducting one section of fixing duration under the control of drop-down control signal.

9. have the control circuit of the booster circuit of fixed switching frequency as claimed in claim 8, it is characterized in that, described conducting duration control circuit comprises:

Controllable current source circuit, has input, output and control end, described input reception control circuit supply voltage, and described control end receives output voltage, and described output exports and the directly proportional variable current of output voltage;

Electric capacity, have first end and the second end, described first end is coupled in the output of controllable current source circuit, described second end ground connection, receives the electric current that controllable current source circuit exports;

First switch, have first end, the second end and control end, described first end is coupled to the first end of electric capacity, described second end ground connection, and described control end receives drop-down control signal;

Controllable voltage source circuit, there is first end, second end, the first control end and the second control end, described second end ground connection, described first control end receives input voltage, described second control end receives output voltage, and described first end exports the directly proportional controllable voltage signal of difference with output voltage and input voltage; And

Turn off comparator, have first input end, the second input and output, described first input end is coupled to the first end of electric capacity, and described second input is coupled to the first end of controllable voltage source circuit, and described output exports and turns off control signal.

10. have the control circuit of the booster circuit of fixed switching frequency as claimed in claim 9, it is characterized in that, described controllable current source circuit comprises:

First resistance, has first end and the second end, described second end ground connection;

Second switch, have first end, the second end and control end, described second end is coupled to the first end of resistance;

First error amplifier, there is first input end, the second input and output, described first input end receives the voltage signal proportional with output voltage, and described second input is coupled to the tie point of resistance and second switch, and described output is coupled to the control end of second switch; And

First current mirroring circuit, has power end, first end and the second end, described power end reception control circuit supply voltage, and described first end is coupled to the first end of second switch, and described second end exports and the directly proportional variable current of output voltage.

11. control circuits as claimed in claim 9 with the booster circuit of fixed switching frequency, it is characterized in that, described controllable voltage source circuit comprises:

Second resistance, has first end and the second end, described second end ground connection;

Second current mirroring circuit, has power end, first end and the second end, and described power end receives input voltage, and described first end is coupled to the first end of the second resistance;

3rd current mirroring circuit, has power end, first end and the second end, described power end ground connection, and described first end is coupled to the second end of the second current mirroring circuit;

3rd resistance, has first end and the second end, and described first end is coupled to the second end of the 3rd current mirroring circuit, described second end ground connection;

4th current mirroring circuit, has power end, first end and the second end, and described power end receives output voltage, and described first end is coupled to the first end of the 3rd resistance; And

4th resistance, has first end and the second end, and described first end is coupled to the second end of the 4th current mirroring circuit, and described second termination is received;

Wherein, described controllable voltage signal produces at the first end of the 3rd resistance.

12. control circuits as claimed in claim 9 with the booster circuit of fixed switching frequency, it is characterized in that, described controllable voltage source circuit comprises:

5th resistance, has first end and the second end, and described first end receives output voltage;

3rd switch, has first end, the second end and control end, and described first end is coupled to the second end of the 5th resistance;

6th resistance, has first end and the second end, and described first end is coupled to the second end of the 3rd switch, described second end ground connection;

7th resistance, has first end and the second end, and described first end receives input voltage; And

Second error amplifier, has first input end, the second input and output, and described first input end is coupled to the second end of the 7th resistance, and described second input is coupled to the second end of the 5th resistance, and described output is coupled to the control end of the 3rd switch.