CN109660131A - A kind of Switching Power Supply power supply circuit, method of supplying power to and switch power supply system - Google Patents

A kind of Switching Power Supply power supply circuit, method of supplying power to and switch power supply system Download PDF

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Publication number
CN109660131A
CN109660131A CN201910031196.3A CN201910031196A CN109660131A CN 109660131 A CN109660131 A CN 109660131A CN 201910031196 A CN201910031196 A CN 201910031196A CN 109660131 A CN109660131 A CN 109660131A
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China
Prior art keywords
power supply
switch
voltage
unit
switch tube
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CN201910031196.3A
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Chinese (zh)
Inventor
杨世红
熊平
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Shaanxi Reactor Microelectronics Co Ltd
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Shaanxi Reactor Microelectronics Co Ltd
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Priority to CN201910031196.3A priority Critical patent/CN109660131A/en
Publication of CN109660131A publication Critical patent/CN109660131A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The disclosure discloses a kind of Switching Power Supply power supply circuit, including start-up resistor, switching circuit, control unit, VccCharging capacitor and VccCharge Management unit；The disclosure further discloses a kind of method of supplying power to of Switching Power Supply；The disclosure further discloses a kind of switch power supply system, including power supply circuit, Overvoltage protecting unit, under-voltage protection unit, voltage signal acquisition unit and feedback unit.The disclosure can be effectively reduced the power consumption generated in start-up course and standby in such a way that the opening time conjunction of control bootstrapping power supply is connected with the drain and gate of voltage driven element respectively by using start-up resistor both ends.

Description

A kind of Switching Power Supply power supply circuit, method of supplying power to and switch power supply system
Technical field
The disclosure belongs to electronic circuit technology field, and in particular to a kind of Switching Power Supply power supply circuit, method of supplying power to and opens Close power-supply system.
Background technique
Switching Power Supply is the power supply conversion equipment of electronic equipment and electronic apparatus, and application is increasingly extensive.With the energy Efficiency and environmental protection become more and more important and to the pay attention to day by day of safety, people propose higher want to the stand-by power consumption of Switching Power Supply It asks.
Power consumption when Switching Power Supply is standby is mainly derived from circuit loss when start-up resistor loss and zero load.Traditional opens Powered-down source circuit as shown in Figure 1, the start-up circuit of Switching Power Supply by start-up resistor RstarWith Vcc charging capacitor C2Composition, when starting Electric current flows through RstarTo C2Charging, after charging voltage reaches internal preset value, control unit starting passes through control switch pipe Switch state maintains charging capacitor C2Voltage.But due to RstarAlways the high input voltage voltage V after rectification is metinAnd Vcc Between, even if also bringing along the lasting consumption of power, and when standby in order to guarantee to provide biggish charging for Switching Power Supply Electric current realizes quick start, selected start-up resistor RstarResistance value it is typically small, RstarThe smaller generation of resistance value standby function It consumes bigger.
In addition, in the conventional circuit structure, since flyback voltage is much higher than Vcc, need to increase resistance R7It limits, the electricity Further increased power dissipation is caused the power consumption of the traditional circuit higher by the introducing of resistance, is unable to satisfy the demand of high energy efficiency product.
To sum up, to solve the problems, such as that circuit power consumption is big in the prior art, it would be highly desirable to design a kind of Switching Power Supply power supply circuit, supply Method for electrically and switch power supply system.
Summary of the invention
Against the above deficiency, the disclosure is designed to provide a kind of Switching Power Supply power supply circuit, method of supplying power to and switch Power-supply system.The disclosure can be effectively reduced in start-up course and standby by the control of bootstrapping power supply opening time section The power consumption of generation；By using the mode that start-up resistor both ends are connected with the drain and gate of voltage driven element respectively, greatly Ground reduces the power consumption generated in starting, normal work and standby by start-up resistor.
The disclosure is achieved through the following technical solutions above-mentioned purpose:
A kind of Switching Power Supply power supply circuit, comprising: start-up resistor, switching circuit, control unit, VccCharging capacitor and Vcc Charge Management unit；Wherein,
Switching circuit includes first switch tube and second switch, drain electrode and the power supply V of first switch tubeinIt is connected, source electrode It is connected with the drain electrode of second switch；
Also, the common end of first switch tube and second switch passes through the VccCharge Management unit and VccCharging electricity Hold and is connected；
The both ends of start-up resistor are connected with the drain and gate of first switch tube respectively；
Control unit is connected with the grid of first switch tube and second switch respectively；
VccCharge Management unit is connected with the source electrode of first switch tube, for guaranteeing the one-way conduction of charge circuit, and it is right Charge circuit carries out current limliting to protect first switch tube.
Preferably, described control unit includes PWM module and drive module；Wherein, the output end of the PWM module and drive The input terminal of dynamic model block is connected, the output end of the drive module grid phase with first switch tube and second switch respectively Even, the PWM module controls the switch state of first switch tube and second switch by drive module, realizes bootstrapping power supply And/or high voltage supply.
Preferably, the first switch tube and second switch are voltage driven type.
The disclosure also provides a kind of method of supplying power to of Switching Power Supply, includes the following steps:
S100: when Switching Power Supply main circuit current rise during, first switch tube in control unit control switch circuit Carrying out bootstrapping power supply with the state of second switch is VccCharging capacitor power supply；
S200: when supply voltage switch is down to preset value, first switch tube and in control unit control switch circuit The state of two switching tubes carries out high voltage supply.
Preferably, before step S100, Switching Power Supply passes through the first switch tube in start-up resistor driving switch circuit Conducting is VccCharging capacitor charges to preset value, starts control unit.
Preferably, the bootstrapping power supply and the starting of high voltage supply, end time pass through timing control and/or voltage detecting It determines；Wherein,
The timing control is according to preset time or time interval starting or to terminate；
The voltage detecting is compared by detection Vcc voltage and with set respective threshold, is tied according to comparing Fruit starting terminates.
Preferably, the step S100 includes:
S101: first switch tube and second switch in control unit driving switch circuit first simultaneously turn on；
S102: turning off second switch after delay a period of time, forms power supply, first switch tube is filled to charging capacitor C2's Power path charges for Vcc, realizes bootstrapping power supply；
S103: second switch is connected again for a period of time and before main circuit current rises to peak value for delay, boots Power supply terminates.
Preferably, in step S200, first switch tube and second switch in described control unit control switch circuit State refers to that the grid voltage of first switch tube is raised to Vcc by control unit, and first switch tube is connected, second switch shutdown.
The disclosure also provides a kind of switch power supply system, comprising: Overvoltage protecting unit, under-voltage protection unit, voltage signal Acquisition unit and feedback unit
The input terminal of the Overvoltage protecting unit is connected with the voltage signal acquisition unit, output end and PWM module phase Even, for generating OVP signal when detecting output voltage beyond preset threshold and exporting to PWM module, entered power supply Press guard mode；
The input terminal of the under-voltage protection unit is connected with the voltage signal acquisition unit, output end and PWM module phase Even, power supply V is being detectedinWhen lower than preset threshold, for generating under-voltage signal and exporting to PWM module, enters power supply and owe Press guard mode；
The voltage signal acquisition unit is connected with Overvoltage protecting unit, under-voltage protection unit respectively, defeated for detecting Voltage and/or Vin out, and feed back to Overvoltage protecting unit, under-voltage protection unit；
The feedback unit is used to detect the variation of output voltage and feeds back to control unit, and passes through control unit PWM module controls duty ratio to adjust output voltage.
Preferably, the feedback unit includes Three-end voltage stabilizer, optocoupler and feedback additional device；
The optocoupler includes diode D3With phototriode Q1；
The feedback additional device includes divider resistance R3、R4、R5、R6、R7With capacitor C3；
The phototriode Q1With capacitor C3One end and V after parallel connectionccThe positive plate or negative plate of charging capacitor are connected, separately One end is connected with PWM module.
Compared with prior art, disclosure bring has the beneficial effect that
1, the control of the characteristic of voltage driven element, the connection type of start-up resistor and bootstrapping power supply opening time section is utilized System, can be effectively reduced the power consumption generated in start-up course and standby；
2, the mode being connected respectively with the drain and gate of voltage driven element by using start-up resistor both ends, greatly Reduce the power consumption generated in starting, normal work and standby by start-up resistor；
3, by design Switching Power Supply bootstrapping power supply, in power supply process of booting, since switching tube is in saturation conduction state, The power of dissipation is minimum, further reduced stand-by power consumption, to make the requirement of product six grades of efficiencies of satisfaction；Meanwhile by certainly The control for lifting power supply opening time section, ensure that the monitoring under on state to the current peak in main circuit, is conducive to by week Phase overcurrent protection；
4, propose the method for supplying power to that combines with high voltage supply of bootstrapping power supply, expand the scope of application, be suitable for it is heavily loaded, The application such as underloading or zero load.
Detailed description of the invention
Fig. 1 is the electrical block diagram of traditional switch power supply；
Fig. 2 is a kind of Switching Power Supply power supply circuit construction schematic diagram that the disclosure proposes；
Fig. 3 is a kind of switch power supply system structural schematic diagram that the disclosure proposes；
Fig. 4 is another switch power supply system structural schematic diagram that the disclosure proposes；
Fig. 5 is a kind of timing sequence of switching power supply schematic diagram that the disclosure proposes.
Label is expressed as follows in figure:
1, power supply circuit；2, Overvoltage protecting unit；3, under-voltage protection unit；4, voltage signal acquisition unit；5, feedback First (51, optocoupler；52, additional device is fed back)；6, absorptive unit；7, output rectification filter unit；11, start-up resistor；12, it switchs Circuit；13, control unit (13-1, PWM module；13-2, drive module)；14,VccCharging capacitor；15,VccCharge Management list Member.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention 1 attached drawing 5, technical solution in the embodiment of the present invention carry out clear Chu is fully described by, it is clear that the described embodiment is only a part of the embodiment of the present invention, instead of all the embodiments.Base Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts it is all its His embodiment, shall fall within the protection scope of the present invention.
Technical solution provided in an embodiment of the present invention is suitable for a variety of circuit topology knots such as Buck, Boost, Buck-Boost Structure does not limit herein；Switching tube involved in technical solution provided in an embodiment of the present invention can be MOS, MOSFET, JFET Equal transistors can be enhanced or depletion type, be illustrated by taking metal-oxide-semiconductor as an example in the embodiment of the present invention；In technical solution The connection being related to can be directly connected to for component, can also be electric connection.
The each embodiment of the present invention is described in detail with reference to the accompanying drawings of the specification.It should be noted that of the invention The displaying sequence of embodiment only represents the sequencing of embodiment, does not represent the superiority and inferiority of technical solution provided by embodiment.
As shown in Fig. 2, the disclosure provides a kind of Switching Power Supply power supply circuit, comprising: start-up resistor 11, switching circuit 12, Control unit 13, VccCharging capacitor 14 and VccCharge Management unit 15；Wherein,
Switching circuit 12 includes first switch tube M1With second switch M2, first switch tube M1Drain electrode and power supply VinPhase Even, source electrode and second switch M2Drain electrode be connected；
Also, first switch tube M1With second switch M2Common end pass through VccCharge Management unit 15 and VccCharging electricity Hold C214 are connected；
Start-up resistor R111 both ends respectively with first switch tube M1Drain and gate be connected；
Control unit 13 respectively with first switch tube M1With second switch M2Grid be connected；
VccCharge Management unit 15 and first switch tube M1Source electrode be connected, for guaranteeing the one-way conduction of charge circuit, And current limliting is carried out to protect first switch tube M to charge circuit1。
Above-described embodiment and start-up resistor R in the prior artstarAlways the high input voltage voltage V after rectification is metinAnd Vcc Between and cause unlike the lasting consumption of power: above-described embodiment by by the both ends of start-up resistor respectively with first switch Pipe M1Drain and gate be connected, power supply gives first switch tube M by start-up resistor1Gate-source parasitic capacitance charging, to raise First switch tube M1Gate source voltage to more than first switch tube M1Threshold voltage make first switch tube M1Conducting, and then formed Power supply, first switch tube M1It is V to the charge path of charging capacitorccWhen charging to preset value, control unit starting.Started Cheng Zhong, due to first switch tube M1Internal resistance it is very big, making alive control when electric current very little, be approximately zero, thus start when start Resistance R1Hardly generate power consumption.
In another embodiment, described control unit includes PWM module and drive module；Wherein, the PWM module is defeated Outlet is connected with the input terminal of drive module, the output end of the drive module respectively with first switch tube and second switch Grid is connected, and the PWM module controls the switch state of first switch tube and second switch by drive module, realizes bootstrapping Power supply and/or high voltage supply.
In the present embodiment, when Switching Power Supply works normally, first switch tube M1, second switch M2It simultaneously turns on, postpones Second switch M after a period of time2Shutdown, at this point, first switch tube M1Gate-source parasitic capacitance CgsGenerate bootstrapping, first switch Pipe M1On state is maintained, is formed and power supply, charging capacitor C2Charge path, be VccCharging, to realize bootstrapping power supply；By In first switch tube M at this time1In bootstrapping state, grid voltage is larger, and is in saturation conduction state, and pressure drop is minimum, thus with it is existing There is technology to compare, the micro power consumption that circuit generates.
Further, as first switch tube M1, second switch M2Being chronically at off state leads to VccWhen electricity shortage, Control unit 13 is by first switch tube M1Grid voltage be raised to Vcc, while the activated resistance R of power supply111 be first switch tube M1's Gate-source parasitic capacitance CgsCharging, raises first switch tube M1Gate source voltage VgsTo more than first switch tube M1Threshold voltage Vth It turns it on, forms power supply, first switch tube M1To VccCharging capacitor C214 charge path carries out high voltage supply.
It is understood that above-described embodiment is compared and the prior art by that will boot power supply and high voltage supply combines Situations such as expanding the scope of application, heavy duty, underloading or zero load can be suitable for.
In another embodiment, the first switch tube M1With second switch M2For voltage driven type.
In the present embodiment, first switch tube M1With second switch M2It can be selected in the transistors such as MOS, MOSFET, JEFT At least one, the preferred NMOS of the present embodiment is as switching tube.
In another embodiment, the disclosure also provides a kind of method of supplying power to of Switching Power Supply, includes the following steps:
S100: when Switching Power Supply main circuit current rise during, middle first switch in control unit control switch circuit It is V that the state of pipe and second switch, which carries out bootstrapping power supply,ccCharging capacitor power supply；
S200: when supply voltage switch is down to preset value, first switch tube and in control unit control switch circuit The state of two switching tubes carries out high voltage supply.
In the specific embodiment of step 100, when Switching Power Supply works normally, the driving switch electricity first of control unit 13 First switch tube M in road 121, second switch M2It simultaneously turns on, turns off second switch M after postponing a period of time2.At this point, First switch tube M1Gate-source parasitic capacitance CgsGenerate bootstrapping, first switch tube M1On state is maintained, power supply, first switch are formed Pipe M1To charging capacitor C2Charge path, be VccBootstrapping power supply is realized in charging；It, will before main circuit current rises to peak value Second switch M2It is connected again, bootstrapping power supply terminates.
It needs to stress, to guarantee the monitoring to main circuit current peak value, realizes Cycle by Cycle overcurrent protection, bootstrapping Power supply process carries out in main circuit current uphill process, i.e., delay a period of time starts bootstrapping power supply after main circuit conducting, And terminate before main circuit current rises to peak value.
In the specific embodiment of step S200, when the working frequency of Switching Power Supply is lower, depending merely on bootstrapping power supply can not Ensure VccPower supply is sufficient, and in particular for products such as adapter or chargers, there are unloaded operation modes, in the case, by In first switch tube M1, second switch M2Being chronically at off state leads to VccTherefore electricity shortage works as V in the present embodimentcc Voltage drop is down to preset threshold Vcc_minWhen, control unit is by first switch tube M1Grid voltage be raised to Vcc, while power supply is activated Resistance R111 be first switch tube M1Gate charges turn it on, carry out high voltage supply.
In another embodiment, before step S100, Switching Power Supply passes through the in start-up resistor driving switch circuit The conducting of one switching tube is VccCharging capacitor charges to preset value, starts control unit.
In the present embodiment, power supply passes through start-up resistor R when starting111 give first switch tube M1Gate-source parasitic capacitance CgsIt fills Electricity raises first switch tube M1Gate source voltage VgsTo more than first switch tube M1Threshold voltage VthMake first switch tube M1It leads It is logical, form power supply, first switch tube M1To VccCharging capacitor C214 charge path is VccCharging capacitor C214 charge to it is default Value, control unit starting.
In another embodiment, the bootstrapping power supply and the starting of high voltage supply, end time by timing control and/or Voltage detecting determines；Wherein,
The timing control is according to preset time or time interval starting or to terminate；
The voltage detecting is compared by detection Vcc voltage and with set respective threshold, is tied according to comparing Fruit starting terminates.
Bootstrapping power supply and starting and terminating for high voltage supply are illustrated individually below:
1, bootstrapping power supply: the M when switch power supply system works normally, in control unit driving switch circuit first1、M2 It simultaneously turns on, turns off M after postponing a period of time2, M at this time1Gate-source parasitic capacitance CgsGenerate bootstrapping, M1Maintain on state, shape At power supply, M1To charging capacitor C2Charge path, be VccBootstrapping power supply is realized in charging；Peak value is risen in main circuit current Before, by M2It is connected again, bootstrapping power supply terminates.
It should be noted that being delayed to turn off M2And M2The time be connected again can pass through VccVoltage monitoring, in VccVoltage It is down to preset threshold Vcc_th2When, M is driven by control unit2Shutdown；In VccVoltage is increased to preset threshold Vcc_th1When, M2Again Conducting.
In addition, being delayed to turn off M2And M2The time be connected again can also be carried out by way of timing control, i.e., when fixed Between point M driven by control circuit2It is switched off and on.
2, high voltage supply: when the working frequency of Switching Power Supply is lower, V can not be ensured by depending merely on bootstrapping power supplyccPower supply is sufficient, In particular for products such as adapter or chargers, there are unloaded operation modes, in the case can be due to M1、M2It is chronically at Off state leads to VccTherefore electricity shortage works as V in the present embodimentccVoltage drop is down to preset threshold Vcc_minWhen, control circuit By M1Grid voltage be raised to Vcc, while the activated resistance R of power supply1For M1Gate charges make M1Conducting carries out high voltage supply.
It should be noted that the unlatching of high voltage supply and end time can also execute according to the preset time, when passing through Sequence control is realized.
In another embodiment, the step S100 includes:
S101: first switch tube and second switch in control unit driving switch circuit first simultaneously turn on；
S102: turning off second switch after delay a period of time, forms power supply, first switch tube is filled to charging capacitor C2's Power path charges for Vcc, realizes bootstrapping power supply；
S103: second switch is connected again for a period of time and before main circuit current rises to peak value for delay, boots Power supply terminates.
In another embodiment, in step S200, first switch tube and second in described control unit control switch circuit The state of switching tube refers to that the grid voltage of first switch tube is raised to Vcc by control unit, first switch tube is connected, second switch Pipe shutdown.
In another embodiment, the disclosure also provides a kind of switch power supply system, including power supply circuit 1, overvoltage protection list Member 2, under-voltage protection unit 3 and voltage signal acquisition unit 4；
The input terminal of the Overvoltage protecting unit (OVP) 2 is connected with the voltage signal acquisition unit 4, output end and institute It states PWM module 13-1 to be connected, for detecting output voltage VoutSignal is generated when beyond preset threshold and is exported to PWM mould Block 13-1 makes power supply enter overvoltage protection state；
The input terminal of the under-voltage protection unit (Brown out) 3 is connected with voltage signal acquisition unit 4, output end with The PWM module 13-1 is connected, and is detecting power supply VinWhen lower than preset threshold, for generating under-voltage signal and exporting to PWM Module 13-1 makes power supply enter under-voltage protection state；
The voltage signal acquisition unit 4 is connected with Overvoltage protecting unit, under-voltage protection unit respectively, defeated for detecting Voltage and/or Vin out, and feed back to Overvoltage protecting unit, under-voltage protection unit；
The feedback unit 5 is used to detect the variation of output voltage and feeds back to control unit, and passes through control unit PWM module controls duty ratio to adjust output voltage.
Fig. 3 is concrete application of the above-described embodiment in double winding secondary side feedback topological structure, it should be noted that this hair Bright switch power supply system is not limited to be applied in double winding secondary side feedback topological structure, can also be applied in other topological structures.
In above-described embodiment, second switch M2Source electrode pass through sampling resistor R2With transformer primary side inductance LpOne end Connection, transformer primary side inductance LpThe other end ground connection.First switch tube M1, second switch M2When connection, primary side conducting, electricity Hold C1The voltage at both ends is added to the primary side of transformer, and electric current is through M1、M2、R2And LpGround is flowed into afterwards, and transformer stores energy；Work as M1、 M2When shutdown, primary side cut-off, transformer passes through secondary side afterflow, carries out the release of energy.
Set on resistance R8、R9Prt pin of the output end of common end through chip and Overvoltage protecting unit (OVP) 2, under-voltage guarantor Shield unit (Brown out) 3 is connected.When primary side cut-off enters flyback phase, L is utilizedpBoth end voltage and output voltage Vout Between turn ratio relationship pass through L as shown in formula (1)pThe voltage monitoring output voltage V at both endsout, realize accurate OPV function.
Np: primary inductor LpThe number of turns；
Ns: secondary inductance LsThe number of turns；
Vf (d2): output diode D2Forward conduction voltage drop.
In primary side conducting, under-voltage protection unit (Brown out) 3, which generates electric current all the way, makes prt voltage and gnd voltage phase Deng due to R2Resistance value very little, V when primary side is connectedinIt is approximately equal with gnd, it is added in R8The voltage at both ends is approximately equal to Vin, then Iprt= Vin/R8, chip interior is by IprtWith reference current IbiasCompare, works as Iprt< IbiasAfter maintaining a period of time, under-voltage protection is triggered Unit (Brown out) 3 is protected, i.e., input undervoltage is protected.
Below with reference to Fig. 2-Fig. 5, the course of work of the present embodiment is described:
When Switching Power Supply starts, VccInitial voltage is zero, power supply VinPass through start-up resistor R1Give switching tube M1Grid add Pressure, gate-source parasitic capacitance CgsCharging, raises first switch tube M1Gate source voltage VgsTo more than its threshold voltage VthLead it It is logical, form power supply, M1To charging capacitor C2Charge path, be VccCharge to preset value Vcc_th0When, control unit starting.It opens During dynamic, due to first switch tube M1Internal resistance it is very big, making alive control when electric current very little, be approximately zero, thus start when Start-up resistor R1Hardly generate power consumption.
Enter normal work stage after Switching Power Supply starting to be passed through by PWM module 13-1 first within a control period Drive module 13-2 controls first switch tube M1, second switch M2It simultaneously turns on, inductance LpElectric current ILpStart to increase, with ILp Increase, sampling resistor R2On voltage VcsAlso it gradually increases, at this time due to VccCharging capacitor is in discharge condition, VccVoltage It reduces；First switch tube M1In saturation conduction state, source-drain voltage VdsIt is minimum.
Delay a period of time or VccIt is reduced to lower threshold Vcc_th2Second switch M is turned off afterwards2, first switch tube at this time M1Gate-source parasitic capacitance CgsGenerate bootstrapping, first switch tube M1On state is maintained, power supply, first switch tube M are formed1To charging Capacitor C2Charge path, be VccBootstrapping power supply is realized in charging.Due to M at this time1In saturation conduction state, pressure drop is minimum, because This, the power of dissipation is small, and efficiency is also higher.Second switch M2Sampling resistor R is flowed through after cut-off2Electric current ended, Vcs It is zero；But since primary side remains as on state, flow through LpElectric current ILpContinue to increase.
Delay a period of time or VccIt is increased to upper limit threshold Vcc_th1Afterwards, PWM module 13-1 drives second switch M2It leads It is logical, VccCharging terminates, C2Into discharge regime, VccVoltage gradually decreases.Primary side enters energy storage stage, main circuit current ILpAfter It is continuous to increase, R2It is in the conductive state, therefore VcsWith ILpIncrease and increase.
Simultaneously turn off first switch tube M1, second switch M2, primary side cut-off, transformer passes through secondary side afterflow, carries out energy Release, drive loaded work piece.Primary side enters flyback phase, VprtHigh level is skipped to, voltage signal acquisition circuit is in high period Between sampled, obtain VoutOutput state.
When underloading or zero load, since frequency is too low, the electricity of primary bootstrapping power supply is unable to maintain that control unit is entirely all The consumption of phase, V after multiple periodsccCapacitor can continuous discharge to under-voltage condition, bootstrapping power supply and high voltage supply are combined, when opening When powered-down source works normally, charging capacitor C still is given by the way of bootstrapping power supply2Charging, leads when being chronically at standby mode Cause VccBrownout into under-voltage protection state or is lower than preset threshold value Vcc_minWhen, control unit is by first switch tube M1's Grid voltage is raised to Vcc, while the activated resistance R of power supply1For first switch tube M1Gate charges, make first switch tube M1Conducting, Carry out high voltage supply.The above control process can also be by sequential logic control, and first switch tube is in M1, second switch M2Cut-off High voltage supply is opened after postponing preset time afterwards.
In another embodiment, the feedback unit 5 includes Three-end voltage stabilizer TL431, optocoupler 51 and feedback auxiliary Device 52；Wherein,
The optocoupler 51 includes diode D3With phototriode Q1；
The feedback additional device 52 includes divider resistance R3、R4、R5、R6、R7With capacitor C3；
The phototriode Q1With capacitor C3One end and V after parallel connectionccThe positive plate or negative plate of charging capacitor are connected, separately One end is connected with PWM module 13-1.
In the present embodiment, output voltage VoutIt is input to TL431 after dividing by divider resistance compared with reference voltage, transports The electric current of optocoupler is flowed through in the error voltage signal control for putting output, as output voltage VoutWhen higher, the electric current for flowing through optocoupler becomes Greatly, the voltage of the port controller FB becomes smaller, and PWM module 13-1 control output duty cycle becomes smaller to reduce transformer and be transmitted to secondary side Energy, output voltage VoutStart to reduce；Conversely, if the inclined V of output voltageoutIt is low, according to the feedback of optocoupler electric current, by PWM mould Block 13-1 controls duty ratio increase to increase the energy that transformer is transmitted to secondary side, to improve output voltage Vout.Pass through the party Formula constantly adjusts control output voltage stabilization in setting value.
In another embodiment, the switch power supply system further includes absorptive unit 6, for avoiding switching tube from ending moment The appearance of excessively high spike damages switching tube.
In the present embodiment, the both ends of the absorptive unit 6 respectively with transformer primary side inductance LpBoth ends be connected, it is described Absorptive unit includes divider resistance R1, capacitor C4With diode D1, resistance R1With capacitor C4One end is through diode D after parallel connection1With Lp Anode be connected, the other end and LpCathode be connected.
In another embodiment, the switch power supply system further includes output rectification filter unit 7, the rectifying and wave-filtering list Member 5 includes diode D2With capacitor C5。
In the present embodiment, when primary side cut-off, secondary side mutual induction electromotive force makes rectifier diode D2Conducting, electric current is on the one hand Load is flowed into, on the other hand to capacitor C5Charging energy-storing releases energy when being connected again so as to primary side to load.
The above is only the section Examples of the disclosure, are not limited to the inventive concept of the disclosure, the technology of this field Personnel centainly can be replaced and be deformed under the principle for not departing from the disclosed invention design, but should fall into the disclosure Protection scope.

Claims (10)

1. a kind of Switching Power Supply power supply circuit, comprising: start-up resistor, switching circuit, control unit, VccCharging capacitor and VccCharging Administrative unit；Wherein,
Switching circuit includes first switch tube and second switch, drain electrode and the power supply V of first switch tubeinIt is connected, source electrode and the The drain electrode of two switching tubes is connected；
Also, the common end of first switch tube and second switch passes through VccCharge Management unit and VccCharging capacitor is connected；
The both ends of start-up resistor are connected with the drain and gate of first switch tube respectively；
Control unit is connected with the grid of first switch tube and second switch respectively；
VccCharge Management unit is connected with the source electrode of first switch tube, for guaranteeing the one-way conduction of charge circuit, and to charging Circuit carries out current limliting to protect first switch tube.
2. Switching Power Supply power supply circuit according to claim 1, which is characterized in that preferred, described control unit includes PWM module and drive module；Wherein, the output end of the PWM module is connected with the input terminal of drive module, the drive module Output end be connected respectively with the grid of first switch tube and second switch, the PWM module passes through drive module control the The switch state of one switching tube and second switch realizes bootstrapping power supply and/or high voltage supply.
3. Switching Power Supply power supply circuit according to claim 1, which is characterized in that the first switch tube and second switch Pipe is voltage driven type.
4. a kind of method of supplying power to of Switching Power Supply, includes the following steps:
S100: when Switching Power Supply is during main circuit current rises, first switch tube and the in control unit control switch circuit It is V that the state of two switching tubes, which carries out bootstrapping power supply,ccCharging capacitor power supply；
S200: when supply voltage switch is down to preset value, first switch tube and second is opened in control unit control switch circuit The state for closing pipe carries out high voltage supply.
5. according to the method described in claim 4, it is characterized in that, Switching Power Supply passes through start-up resistor before step S100 First switch tube conducting in driving switch circuit, is VccCharging capacitor charges to preset value, starts control unit.
6. method of supplying power to according to claim 4, which is characterized in that the bootstrapping power supply and the starting of high voltage supply, knot The beam time is determined by timing control and/or voltage detecting；Wherein,
The timing control is according to preset time or time interval starting or to terminate；
The voltage detecting is compared by detection Vcc voltage and with set respective threshold, is opened according to comparison result Dynamic or end.
7. method of supplying power to according to claim 4, which is characterized in that the step S100 includes:
S101: first switch tube and second switch in control unit driving switch circuit first simultaneously turn on；
S102: turning off second switch after delay a period of time, forms the charging circuit of power supply, first switch tube to charging capacitor C2 Diameter charges for Vcc, realizes bootstrapping power supply；
S103: second switch is connected again for a period of time and before main circuit current rises to peak value for delay, bootstrapping power supply Terminate.
8. method of supplying power to according to claim 4, which is characterized in that in step S200, described control unit control switch The state of first switch tube and second switch refers to that the grid voltage of first switch tube is raised to Vcc by control unit in circuit, makes First switch tube conducting, second switch shutdown.
9. a kind of switch power supply system comprising Switching Power Supply power supply circuit described in claim 1-3, comprising: overvoltage protection list Member, under-voltage protection unit, voltage signal acquisition unit and feedback unit；
The input terminal of the Overvoltage protecting unit is connected with the voltage signal acquisition unit, output end and the PWM module phase Even, for generating signal when detecting output voltage beyond preset threshold and exporting to PWM module, power supply is made to enter over-voltage guarantor Shield state；
The input terminal of the under-voltage protection unit is connected with the voltage signal acquisition unit, output end and the PWM module phase Even, power supply V is being detectedinWhen lower than preset threshold, for generating under-voltage signal and exporting to PWM module, enters power supply and owe Press guard mode；
The voltage signal acquisition unit is connected with Overvoltage protecting unit, under-voltage protection unit respectively, for detecting output electricity Pressure and/or Vin, and feed back to Overvoltage protecting unit, under-voltage protection unit；
The feedback unit is used to detect the variation of output voltage and feeds back to control unit, and passes through the PWM mould of control unit Block controls duty ratio to adjust output voltage.
10. switch power supply system according to claim 9, which is characterized in that the feedback unit includes three terminal regulator Part, optocoupler and feedback additional device；Wherein,
The optocoupler includes diode D3With phototriode Q1；
The feedback additional device includes divider resistance R3、R4、R5、R6、R7With capacitor C3；
The phototriode Q1With capacitor C3One end and V after parallel connectionccThe positive plate or negative plate of charging capacitor are connected, the other end It is connected with PWM module.
CN201910031196.3A 2019-01-11 2019-01-11 A kind of Switching Power Supply power supply circuit, method of supplying power to and switch power supply system Pending CN109660131A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110198125A (en) * 2019-06-27 2019-09-03 上海新进芯微电子有限公司 A kind of Switching Power Supply and its system output short circuit protection circuit and method
CN110518790A (en) * 2019-08-28 2019-11-29 南京微盟电子有限公司 A kind of quick start and self-contained electric system of switching power converters
CN112421971A (en) * 2019-08-21 2021-02-26 万国半导体(开曼)股份有限公司 Power supply conversion system and control method
CN116613619A (en) * 2022-10-24 2023-08-18 深圳市中图仪器股份有限公司 Laser power supply system with overvoltage protection function

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110198125A (en) * 2019-06-27 2019-09-03 上海新进芯微电子有限公司 A kind of Switching Power Supply and its system output short circuit protection circuit and method
CN112421971A (en) * 2019-08-21 2021-02-26 万国半导体(开曼)股份有限公司 Power supply conversion system and control method
CN110518790A (en) * 2019-08-28 2019-11-29 南京微盟电子有限公司 A kind of quick start and self-contained electric system of switching power converters
CN116613619A (en) * 2022-10-24 2023-08-18 深圳市中图仪器股份有限公司 Laser power supply system with overvoltage protection function
CN116613619B (en) * 2022-10-24 2024-01-02 深圳市中图仪器股份有限公司 Laser power supply system with overvoltage protection function

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