CN103001463B - Switch power controller and the Switching Power Supply that comprises this switch power controller - Google Patents

Abstract

The Switching Power Supply that the invention provides a kind of switch power controller and comprise this switch power controller, this controller comprises: zero cross detection circuit, carries out zero passage detection and produces zero cross signal the feedback signal of input; Input voltage detection circuit, detects input voltage; Output voltage detecting circuit, detects output voltage; ON time length control module, produce cut-off signals according to input voltage, output voltage and bucking voltage, so that the ON time of switching tube is associated with input voltage, output voltage, described ON time increases and reduces in the time that described output voltage raises in the time that described input voltage raises; Rest-set flip-flop, its set input receives described zero cross signal, and its RESET input receives described cut-off signals, and its output produces and drives signal to control the turn-on and turn-off of switching tube of described Switching Power Supply. The present invention can optimize the power factor of the Switching Power Supply of critical conduction mode control, reduces total harmonic distortion.

Description

Switch power controller and the Switching Power Supply that comprises this switch power controller

Technical field

The present invention relates to switch power technology, relate in particular to one and there is power factor adjustment function, critical leadingThe switch power controller of logical pattern control, and the Switching Power Supply that comprises this switch power controller.

Background technology

Isolation traditional Alternating Current Power Supply, that be with power factor adjustment (PFC) function, critical conduction modeLED constant-current drive circuit as shown in Figure 1, mainly comprises: AC input rectification circuit 101, interchange inputSource 102, input capacitance Cin, resistance 104, electric capacity 105, diode 106, isolating transformer T1, meritRate switch 112, sampling resistor Rs, resistance 113, output commutation diode D1, output capacitance Cbulk,Constant-current switch power source controller 100. Wherein, controller 100 is for receiving from isolating transformer T1'sThe feedback signal FB of auxiliary group of winding L 3, the former limit winding L 1 of sampling resistor Rs sampling isolating transformer T1Primary current, and driving power switch 112, is passed to input energy defeated by isolating transformer T1Go out.

Constant-current switch power source controller 100 comprises: zero cross detection circuit 125, and for detection of driving signalFeedback signal FB zero passage after GD finishes provides opening of power switch 112 in the time of feedback signal FB zero passageMessenger, conducting power switch 112, zero cross detection circuit 125 also obtains the degaussing time of transformer T1Tdemag, and transmit it to constant-current control circuit 120; Constant current counting circuit 120, by the electricity of samplingVoltage on resistance Rs is sampled and is obtained former limit peak point current, obtains transformer by zero cross detection circuit 125The degaussing time T demag of T1, this degaussing time T demag is exactly the electric current of output commutation diode D1ON time, is calculated the size of output current by former limit peak point current, transformer degaussing time T demag;Error amplifier 121, the output current that constant current counting circuit 120 calculates and reference current do error and amplify,Output error voltage COMP, error voltage COMP connects building-out capacitor 114, makes after loop stability,Error voltage COMP is substantially fixing; ON time length control circuit 122, power ratio control switch 112ON time length, in the time that power switch 112 starts conducting, start timing, in the time reaching the conducting of settingBetween time, output cut-off signals to trigger 123, remove switch-off power switch 112, after loop stability, mistakeWhen potential difference COMP fixes, the ON time consistent length of power switch 112, realize thus power because ofNumber is adjusted; Trigger 123, when the zero cross signal ZCD that reception zero cross detection circuit 125 is exported and conductingBetween the cut-off signals exported of length control circuit 122; Drive circuit 124, connects trigger 123 and powerThe drive end of switch 112, realizes the driving that turns on and off to power switch 112.

Adjust effect for realizing good power factor, require the AC input current of each switch periods canWell follow the variation of input voltage. Under critical conduction mode, ignore output commutation diode pressure drop,Pressure drop when input rectifying tube voltage drop, power switch conducting, the average current input of each switch periods is:

$I_{\mathrm{in}}=\frac{1}{2}\·\frac{n\·V_{\mathrm{out}}}{V_{\mathrm{in}}+n\·V_{\mathrm{out}}}\·\frac{T_{\mathrm{on}}\·V_{\mathrm{in}}}{L}---\left(1\right)$

Wherein, n is the former limit winding L 1 of transformer T1 and the turn ratio of secondary winding L 2, V_outFor exporting electricityPress V_inFor input voltage, I_inFor input current, T_onFor ON time, L is the inductance of former limit winding L 1.Adopt fixing ON time (T_onConstant), when critical conduction mode control, input current I_inCan not be completeFollow input voltage V_inChange, power factor variation, total harmonic distortion strengthens, and input voltage V_inMoreHeight, deviation is larger, so the power factor of at present traditional circuit is not good especially, total harmonic distortion is alsoLarger.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of switch power controller and comprises this Switching Power SupplyThe Switching Power Supply of controller, the power factor of the Switching Power Supply of optimization critical conduction mode control, reduces always humorousRipple distortion.

For solving the problems of the technologies described above, the invention provides a kind of Switching Power Supply control of critical conduction mode controlDevice processed, comprising:

Zero cross detection circuit, carries out zero passage detection and produces zero cross signal the feedback signal of input;

Input voltage detection circuit, detects the input voltage of Switching Power Supply;

Output voltage detecting circuit, detects the output voltage of described Switching Power Supply;

ON time length control module, with output, the output voltage inspection of described input voltage detection circuitThe output of slowdown monitoring circuit is connected, and receives the bucking voltage on loop compensation electric capacity, according to described Switching Power SupplyInput voltage, output voltage and bucking voltage produce cut-off signals so that the switch of described Switching Power SupplyThe ON time of pipe is associated with the input voltage of described Switching Power Supply, output voltage, and described ON time existsWhen described input voltage raises, increase and reduce in the time that described output voltage raises;

Rest-set flip-flop, its set input receives described zero cross signal, and its RESET input receives described passBreak signal, its output produces and drives signal to control the turn-on and turn-off of switching tube of described Switching Power Supply.

According to one embodiment of present invention, the cut-off signals of described ON time length control module generation makesThe ON time of the switching tube of described Switching Power Supply meets following relation:Keep fixing, itsIn, the former limit winding of the transformer that n is described Switching Power Supply and the turn ratio of secondary winding, V_outOpen for describedClose the output voltage of power supply, V_inFor the input voltage of described Switching Power Supply, T_onFor opening of described Switching Power SupplyClose the ON time of pipe.

According to one embodiment of present invention, described ON time length control module comprises:

ON time length control circuit, connects output, the output voltage of described input voltage detection circuitThe output of testing circuit, and receive the bucking voltage on described loop compensation electric capacity, by described Switching Power SupplySwitching tube start conducting trigger start timing, the ON time that reaches setting produces described cut-off signals,The ON time of described setting is associated with described bucking voltage, input voltage and output voltage, described defeatedEnter and when voltage raises, increase and reduce in the time that described output voltage raises.

According to one embodiment of present invention, described ON time length control module comprises:

Multiplier, connects the output of described input voltage detection circuit, the output of output voltage detecting circuitEnd, and receive the bucking voltage on described loop compensation electric capacity, the output signal of described multiplier is described defeatedEnter the quadratic function of voltage and reduce with the rising of described output voltage;

Peak point current comparator, connects the output of described multiplier and the sampling resistor of described Switching Power SupplyFirst end, the first end of described sampling resistor connects the output of described switching tube, described sampling resistorThe second end ground connection, after described switching tube conducting, the voltage at described sampling resistor two ends raises, in described samplingThe voltage at resistance two ends produces described cut-off signals while exceeding the output signal of described multiplier.

According to one embodiment of present invention, described switch power controller also comprises:

Constant current counting circuit, the primary current of the switching tube to the described Switching Power Supply of flowing through is sampled, and obtainsFormer limit peak point current, and the transformer degaussing of being exported by described former limit peak point current and described zero cross detection circuitTime Calculation output current;

Error amplifier, the output current to described constant current counting circuit output and default reference current carry outError is amplified, output error voltage, and described error voltage is applied on described loop compensation electric capacity.

According to one embodiment of present invention, described switch power controller also comprises:

Voltage sampling circuit, the voltage of the switching tube output to described Switching Power Supply is sampled, and obtains peakValue sampled voltage;

Error amplifier, the peak value sampling voltage to described voltage sampling circuit output and default reference voltageCarry out error amplification, output error voltage, described error voltage is applied on described loop compensation electric capacity.

According to one embodiment of present invention, the input of described input voltage detection circuit and described input electricityThe pin of pressing is connected, and directly described input voltage is sampled.

According to one embodiment of present invention, the input of described input voltage detection circuit and described auxiliary aroundGroup is connected, during for detection of the switching tube conducting of described Switching Power Supply described in negative pressure on auxiliary winding, this is negativePress relevant to described input voltage.

According to one embodiment of present invention, the input of described output voltage detecting circuit and described auxiliary aroundGroup is connected, and turn-offs after Preset Time section on described auxiliary winding for detection of the switching tube of described Switching Power SupplyPositive voltage, this positive voltage is relevant to described output voltage.

The present invention also provides a kind of reverse exciting topological Switching Power Supply, comprises the switch electricity described in above any oneSource controller.

The present invention also provides a kind of buck Switching Power Supply, comprises the Switching Power Supply control described in above any oneDevice processed.

Compared with prior art, the present invention has the following advantages:

The switch power controller of the embodiment of the present invention by amendment switching tube the switch conduction time, make itself andInput voltage, the output voltage of Switching Power Supply are associated, thereby have improved the power factor of circuit, have reducedThe total harmonic distortion of Switching Power Supply.

Furthermore, the ON time of switching tube meetsKeep fixing, make input electricityStream is followed input voltage completely and is changed, and realizes good power factor performance.

Brief description of the drawings

Fig. 1 is that one of the prior art has power factor adjustment function, adopts fixing ON time controlThe electrical block diagram of the LED constant-flow driver of system, critical conduction mode control;

Fig. 2 is that the power factor that has of the embodiment of the present invention is adjusted function, adopted ON time control, criticalThe electrical block diagram of the reverse exciting topological LED constant-flow driver of conduction mode control;

Fig. 3 is that the power factor that has of the embodiment of the present invention is adjusted function, optimized multiplier and adopt peak electricityThe electrical block diagram of the reverse exciting topological LED constant-current controller of current control, critical conduction mode control;

Fig. 4 is that the power factor that has of the embodiment of the present invention is adjusted function, optimized multiplier and adopt peak electricityThe electrical block diagram of the buck topology LED constant-current controller of current control, critical conduction mode control.

Detailed description of the invention

Known according to the formula in background technology (1), because input current can not be followed input voltage completelyVariation is because fixing ON time control causes, so for optimizing power factor, optimize total harmonic waveDistortion, can revise ON time length, and fixing ON time length is revised as and input voltage, outputThe ON time length that voltage is relevant.

Further, according to formula (1), in order to realize good power factor, need input electricityStream is followed input voltage completely and is changed, and therefore needs to ensureFixing, thus improve power because ofNumber, the ON time of switching tube and input voltage, output voltage are relevant.

Below in conjunction with specific embodiments and the drawings, the invention will be further described, but should not limit with thisProtection scope of the present invention.

With reference to figure 2, Fig. 2 shows the circuit structure signal of the reverse exciting topological Switching Power Supply of the first embodimentFigure, this reverse exciting topological Switching Power Supply can be used as LED driver. As described in Figure 2, this Switching Power SupplyComprise: AC signal source 102, rectifier bridge 101, input capacitance Cin, resistance 104, electric capacity 105, twoUtmost point pipe 106, transformer T1(comprise former limit winding L 1, secondary winding L 2, auxiliary winding L 3), openClose pipe 112, sampling resistor Rs, resistance 113, loop compensation electric capacity 114, output diode D1, outputCapacitor C bulk and switch power controller 200, the integrated connection mode of above-mentioned all parts and routineInverse-excitation type switch power-supply is identical, for example identical with the Integral connection structure of Fig. 1 in background technology.

In the present embodiment, switch power controller 200 comprises: zero cross detection circuit 125, input voltage inspectionSlowdown monitoring circuit 126, output voltage detecting circuit 127, constant current counting circuit 120, error amplifier 121, leadIn logical time span control module 132(the present embodiment, be specially ON time length control circuit 132),Rest-set flip-flop 123, driver 124.

Wherein, zero cross detection circuit 125 carries out zero passage detection and produces zero passage the feedback signal FB of inputSignal ZCD, this feedback signal FB comes from the different name end of the auxiliary winding L 3 of transformer T1, viaResistance 113 inputs to zero cross detection circuit 125. Zero cross detection circuit 125 also detects going of transformer T1Magnetic time T demag, and transmit it to constant current counting circuit 120.

Input voltage detection circuit 126 detects the input voltage vin of Switching Power Supply, and will detect knotFruit transfers to ON time length control circuit 132.

In an instantiation, the input of input voltage detection circuit 126 can and input voltage vinPin be connected, directly input voltage vin is sampled to obtain testing result.

In another instantiation, the input of input voltage detection circuit 126 also can with auxiliary windingL3 is connected, and the negative pressure during by 112 conducting of sense switch pipe in auxiliary winding L 3 obtains testing result,This negative pressure is relevant to input voltage vin.

Output voltage detecting circuit 127 detects the output voltage V out of Switching Power Supply, and will detectResult transfers to ON time length control circuit 132.

In one example, the input of output voltage detecting circuit 127 can be connected with auxiliary winding L 3,Turn-off after Preset Time section at switching tube 112, examined by the positive voltage detecting in auxiliary winding L 3Survey result, this positive voltage is relevant to output voltage V out.

Output, the output voltage of ON time length control module 132 and input voltage detection circuit 126The output of testing circuit 127 is connected, and receives the bucking voltage COMP on loop compensation electric capacity 114,Produce and turn-off according to the input voltage vin of Switching Power Supply, output voltage V out and bucking voltage COMPSignal increases the ON time of switching tube 112 and at output voltage in the time that input voltage vin raisesVout reduces while rising.

More specifically, in the embodiment shown in Figure 2, ON time length control module 132 is concreteFor ON time length control circuit 132, it connects output, the output of input voltage detection circuit 126The output of voltage detecting circuit 127, and receive the bucking voltage COMP on loop compensation electric capacity 114,Start conducting by switching tube 112 and trigger and start timing, the ON time that reaches setting produces and turn-offs letterNumber, the ON time of this setting and bucking voltage COMP, input voltage vin and output voltage V out phaseAssociation increases and reduces in the time that output voltage V out raises in the time that input voltage vin raises.

As a preferred embodiment, the cut-off signals that ON time length control circuit 132 produces makesThe ON time of switching tube 112 meets following relation:Keep fixing, wherein, n is for openingThe former limit winding L 1 of the transformer T1 of pass power supply and the turn ratio of secondary winding L 2, V_outFor Switching Power SupplyOutput voltage, V_inFor the input voltage of Switching Power Supply, T_onFor the ON time of switching tube 112.

Constant current counting circuit 120 is sampled to the primary current of the switching tube 112 of flowing through, and obtains former limit peak valueElectric current, and the transformer degaussing time T demag being exported by this former limit peak point current and zero cross detection circuit 125Calculate output current; The output current that error amplifier 121 is exported constant current counting circuit 120 is with defaultReference current carries out error amplification, output error voltage, and this error voltage is applied to described loop compensation electric capacityUpper, in the time of loop stability, this error voltage is the bucking voltage COMP on loop compensation electric capacity 114.

The set input of rest-set flip-flop 123 receives zero cross signal ZCD, and the RESET input receives self-conductanceThe cut-off signals of logical time span control circuit 132, its output produces and drives signal with gauge tap pipe112 turn-on and turn-off. As a nonrestrictive example, this driving signal via driver 124 afterTransfer to the control end of switching tube 112.

Furthermore, for ON time length control circuit 132, ON time length control circuit 132Conventionally by electric current, discharging and recharging of electric capacity realized to timing, suppose that the charging current of timing is I₁, electric capacity is C₁，Comparison point voltage is V_ref1,

$T_{\mathrm{on}}=\frac{V_{\mathrm{ref}1}\·C_1}{I_1}---\left(2\right)$

Wherein T_onFor ON time. For fixing T_onCircuit, setting compensation voltage COMP isV_ref1, the charging current I of timing₁For constant, because being one after loop stability, determines bucking voltage COMPValue, therefore can realize the fixing effect of ON time.

As previously mentioned, in order to realizeConstant in to improve power factor, needConstant, detecting input voltage V_in, the turn ratio is taken advantage of output voltage nV_outAfter, holdEasily realize$\frac{n\·V_{\mathrm{out}}}{V_{\mathrm{in}}+n\·V_{\mathrm{out}}}\·\frac{V_{\mathrm{ref}1}\·C_1}{I_1}$Constant.

If setting compensation voltage COMP is V_ref1, control charging current I regularly₁Can be expressed asWherein I₀For constant, have

$\frac{n\·V_{\mathrm{out}}}{V_{\mathrm{in}}+n\·V_{\mathrm{out}}}\·T_{\mathrm{on}}=\frac{V_{\mathrm{ref}1}\·C_1}{I_0}---\left(3\right)$

For constant.

As input voltage V_inWhen very low, the charging current I of timing₁For I₀, as input voltage V_inWhen very high,The charging current I of timing₁Reduce. Work as output voltage V_outWhen lower, the charging current I of timing₁Less, defeatedGo out voltage V_outWhen rising, the charging current I of timing₁Raise.

If setting compensation voltage COMP becomes the I in formula (2) through voltage current transducer₁, Ke YizhiRoad, after loop stability, I₁Be a stable quantity, need to control V_ref1With input voltage V_in, output voltageV_outRelevant, arrangeWherein V_ref0It is the constant that inside circuit is set. By upperCan know by inference and have:

$\frac{n\·V_{\mathrm{out}}}{V_{\mathrm{in}}+n\·V_{\mathrm{out}}}\·T_{\mathrm{on}}=\frac{V_{\mathrm{ref}0}\·C_1}{I_1}---\left(4\right)$

For constant.

In the time that input voltage is very low, comparison point voltage V_ref1For V_ref0, as input voltage V_inWhen rising, relativelyPoint voltage V_ref1Raise; Work as output voltage V_outWhen lower, comparison point voltage V_ref1Larger; Output voltage V_outRiseGao Shi, comparison point voltage V_ref1Reduce.

The final purpose of the implementation method of above two kinds of ON time length control circuits is identical, realizes conductingTime span increases in the time that input voltage raises, and ON time length reduces in the time that output voltage raises.

EnsureFixing, can well realize input current and follow input voltage. Near when adoptingLike when method, realize the function that ON time length increases in the time that input voltage raises, ON time lengthThe function reducing in the time that output voltage raises, with respect to fixing ON time control circuit, can be effectiveThe power factor that improves circuit, reduces total harmonic distortion.

Fig. 3 shows the circuit structure of the reverse exciting topological Switching Power Supply of another embodiment of the present invention, its entiretyStructure is identical with the embodiment shown in Fig. 2, and difference is switch power controller 300 and opening shown in Fig. 2Close power-supply controller of electric 200 and have difference.

Particularly, in the embodiment shown in fig. 3, switch power controller 300 comprises: zero passage detectionCircuit 125, input voltage detection circuit 126, output voltage detecting circuit 127, constant current counting circuit 120,Error amplifier 121, ON time length control module, rest-set flip-flop 123, driver 124.

Different from last embodiment, what in the present embodiment, ON time length control module adopted is to optimizeMultiplier is in conjunction with the mode of peak point current control, and wherein the input of multiplier not only contains input voltage signal,Also contain output voltage signal, the output quantity of multiplier is also different.

Particularly, ON time length control module comprises multiplier 148 and peak point current comparator 149.Wherein, multiplier 148 connects output, the output voltage detecting circuit of input voltage detection circuit 126127 output, and receive the bucking voltage COMP on loop compensation electric capacity 114, multiplier 148Output signal be Switching Power Supply input voltage vin quadratic function and subtract with the rising of output voltage V outLittle. Peak point current comparator 149 connects the output of multiplier 148 and the sampling resistor of Switching Power SupplyThe first end of Rs, the output of the first end connecting valve pipe 112 of sampling resistor Rs, sampling resistor RsThe second end ground connection. Output signal and the sampling resistor Rs of peak point current comparator 149 to multiplier 148On voltage compare, after switching tube 112 conductings, the voltage at sampling resistor Rs two ends raises,The voltage at sampling resistor Rs two ends produces cut-off signals while exceeding the output signal of multiplier 148.

Now, the expression formula of input current changes into:

$I_{\mathrm{in}}=\frac{1}{2}\·\frac{n\·V_{\mathrm{out}}}{V_{\mathrm{in}}+n\·V_{\mathrm{out}}}\·I_{\mathrm{pk}}---\left(5\right)$

Wherein I_pkFor former limit peak point current, the implication of other parameters is consistent with aforementioned content. Accomplish inputElectric current and input voltage are followed completely, require:

$\frac{n\·V_{\mathrm{out}}}{V_{\mathrm{in}}+n{\·V}_{\mathrm{out}}}\·I_{\mathrm{pk}}=K_1\·V_{\mathrm{in}};$

Wherein K1 is constant.

After arrangement, obtain:$I_{\mathrm{pk}}=K_1\·V_{\mathrm{in}}\·\frac{V_{\mathrm{in}}+n\·V_{\mathrm{out}}}{n\·V_{\mathrm{out}}}=\frac{K_1\·V_{\mathrm{in}}^2}{n\·V_{\mathrm{out}}}+K_1\·V_{\mathrm{in}}.$

The output that is multiplier 148 forms by two parts are cumulative, and a part is directly proportional to input voltage vin,Square being directly proportional of another part and input voltage vin, out is inversely proportional to output voltage V. Or change speechIt, the output of multiplier 148 is quadratic functions of input voltage vin. The output of multiplier 148 is also with defeatedGo out voltage Vout relevant, with the rising of output voltage V out, the output of multiplier 148 reduces. And it is existingIn technology, in traditional multiplier architecture, only comprise the part being directly proportional to input voltage value.

With reference to figure 4, Fig. 4 shows the circuit structure of the Switching Power Supply in another embodiment. Shown in Fig. 4Embodiment in, the switch power controller in Fig. 3 300 is applied in the Switching Power Supply of buck structure,The peripheral circuit structure of this buck Switching Power Supply can be any suitable circuit structure. As a non-limitThe example of property processed, the peripheral circuit of the buck Switching Power Supply shown in Fig. 4 comprises: interchange input source 102,Rectifier bridge 101, input capacitance Cin, resistance 104, electric capacity 105, diode 106, transformer T2(bagDraw together former limit winding L 4 and auxiliary winding L 5), switching tube 112, sampling resistor Rs, resistance 113, loopBuilding-out capacitor 114, output diode D1, output capacitance Cbulk.

Preferably, in order to make input current follow input voltage vin completely, should makeProtectHold fixing (being also turn ratio n=1).

It should be noted that, the switch power controller 200 shown in Fig. 2 also goes for shown in Fig. 4Buck Switching Power Supply.

It will be appreciated by those skilled in the art that what in the embodiment shown in Fig. 2, Fig. 3 and Fig. 4, adopt is permanentCurrent control loop, its control be LED output current, wherein loop compensation electric capacity 114 is mended for loopRepay. If adopt constant voltage control loop, controlled quentity controlled variable be changed to output voltage V out, loop compensation electric capacity114 stability for bucking voltage loop, bucking voltage COMP is that error is amplified voltage. Particularly,Constant current counting circuit 120 in Fig. 2, Fig. 3, Fig. 4 is replaced by voltage sampling circuit, to switching tube 112The voltage of output is sampled, and obtains peak value sampling voltage; And error amplifier 121 changes into voltage is adoptedThe peak value sampling voltage of sample circuit output and default reference voltage carry out error amplification, output error voltage,This error voltage is applied on loop compensation electric capacity 114; Other circuit structures are constant, can realize power because ofNumber is adjusted, and realizes output voltage constant simultaneously.

In addition, for the embodiment shown in Fig. 3 and Fig. 4, the input of input voltage detection circuit 126Can be connected with the pin of input voltage vin, directly input voltage vin be sampled to obtain to detect knotReally. Or the input of input voltage detection circuit 126 also can be connected with auxiliary winding L 3, passes throughNegative pressure when 112 conducting of sense switch pipe in auxiliary winding L 3 obtains testing result, this negative pressure and inputVoltage Vin is relevant. And the input of output voltage detecting circuit 127 can be connected with auxiliary winding L 3,Turn-off after Preset Time section at switching tube 112, examined by the positive voltage detecting in auxiliary winding L 3Survey result, this positive voltage is relevant to output voltage V out.

The invention discloses and there is power factor adjustment function, the Switching Power Supply of critical conduction mode controlController, and describe the specific embodiment of the present invention and effect with reference to the accompanying drawings. Should be understood thatBe above-described embodiment just to explanation of the present invention, instead of limitation of the present invention, any superGo out the innovation and creation within the scope of connotation of the present invention, comprise zero cross detection circuit, ON time lengthControl circuit, flip-flop circuit, multiplier, the change of the local structure to circuit, to components and partsThe replacement of type or model, and the replacement of other unsubstantialities or amendment, all fall into the present invention's protectionWithin scope.

Claims (9)

1. a switch power controller for critical conduction mode control, is characterized in that, comprising:

Zero cross detection circuit, carries out zero passage detection and produces zero cross signal the feedback signal of input;

Input voltage detection circuit, detects the input voltage of Switching Power Supply;

Output voltage detecting circuit, detects the output voltage of described Switching Power Supply;

ON time length control module, with output, the output voltage inspection of described input voltage detection circuitThe output of slowdown monitoring circuit is connected, and receives the bucking voltage on loop compensation electric capacity, according to described Switching Power SupplyInput voltage, output voltage and bucking voltage produce cut-off signals so that the switch of described Switching Power SupplyThe ON time of pipe is associated with the input voltage of described Switching Power Supply, output voltage, and described ON time existsWhen described input voltage raises, increase and reduce in the time that described output voltage raises;

Rest-set flip-flop, its set input receives described zero cross signal, and its RESET input receives described passBreak signal, its output produces and drives signal to control the turn-on and turn-off of switching tube of described Switching Power Supply;

Wherein, described ON time length control module comprises:

ON time length control circuit, connects output, the output voltage of described input voltage detection circuitThe output of testing circuit, and receive the bucking voltage on described loop compensation electric capacity, by described Switching Power SupplySwitching tube start conducting trigger start timing, the ON time that reaches setting produces described cut-off signals,The ON time of described setting is associated with described bucking voltage, input voltage and output voltage, described defeatedEnter and when voltage raises, increase and reduce in the time that described output voltage raises.

2. switch power controller according to claim 1, is characterized in that, described ON timeThe cut-off signals that length control module produces makes the ON time of the switching tube of described Switching Power Supply meet as followsRelation:Keep fixing, wherein, the former limit winding of the transformer that n is described Switching Power SupplyWith the turn ratio of secondary winding, V_outFor the output voltage of described Switching Power Supply, V_inFor described Switching Power SupplyInput voltage, T_onFor the ON time of the switching tube of described Switching Power Supply.

3. according to the switch power controller described in any one in claim 1 to 2, it is characterized in that,Also comprise:

Constant current counting circuit, the primary current of the switching tube to the described Switching Power Supply of flowing through is sampled, and obtainsFormer limit peak point current, and the transformer degaussing of being exported by described former limit peak point current and described zero cross detection circuitTime Calculation output current;

Error amplifier, the output current to described constant current counting circuit output and default reference current carry outError is amplified, output error voltage, and described error voltage is applied on described loop compensation electric capacity.

4. according to the switch power controller described in any one in claim 1 to 2, it is characterized in that,Also comprise:

Voltage sampling circuit, the voltage of the switching tube output to described Switching Power Supply is sampled, and obtains peakValue sampled voltage;

Error amplifier, the peak value sampling voltage to described voltage sampling circuit output and default reference voltageCarry out error amplification, output error voltage, described error voltage is applied on described loop compensation electric capacity.

5. switch power controller according to claim 1, is characterized in that, described input voltageThe input of testing circuit is connected with the pin of described input voltage, directly described input voltage is adoptedSample.

6. switch power controller according to claim 1, is characterized in that, described input voltageThe input of testing circuit is connected with the auxiliary winding of the transformer of described Switching Power Supply, opens for detection of describedNegative pressure described in while closing the switching tube conducting of power supply on auxiliary winding, this negative pressure is relevant to described input voltage.

7. switch power controller according to claim 1, is characterized in that, described output voltageThe input of testing circuit is connected with the auxiliary winding of the transformer of described Switching Power Supply, opens for detection of describedThe switching tube that closes power supply turn-offs the positive voltage on described auxiliary winding after Preset Time section, this positive voltage with described inOutput voltage is relevant.

8. a reverse exciting topological Switching Power Supply, is characterized in that, comprises in claim 1 to 7 arbitrarySwitch power controller described in.

9. a buck Switching Power Supply, is characterized in that, comprises any one institute in claim 1 to 7The switch power controller of stating.