CN206023605U

CN206023605U - The Switching Power Supply of primary-side-control

Info

Publication number: CN206023605U
Application number: CN201620852460.1U
Authority: CN
Inventors: 王栋
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2016-08-08
Filing date: 2016-08-08
Publication date: 2017-03-15
Anticipated expiration: 2026-08-08

Abstract

This application discloses the Switching Power Supply of primary-side-control.The Switching Power Supply of the primary-side-control includes：Transformator, including primary side winding and vice-side winding；First switch pipe, first switch pipe and primary side winding are connected in series between DC voltage input end and ground；Current sampling resistor, for obtaining the current sampling signal for characterizing the electric current for flowing through first switch pipe；Voltage feedback circuit, for obtaining the voltage feedback signal of the original edge voltage for characterizing primary side winding；Control circuit, controls the conducting and disconnection of first switch pipe；And power supply circuits, for producing control voltage for control circuit, wherein, control circuit obtains current sampling signal from the first end of primary side winding, and power supply circuits are additionally operable to the peak voltage for absorbing first switch pipe alternate conduction and producing when disconnecting, so as to suppress to disturb.The Switching Power Supply can save assists winding and absorption circuit, such that it is able to realize wide output voltage and reduces cost.

Description

The Switching Power Supply of primary-side-control

Technical field

This utility model is related to switch power technology, more particularly, to the Switching Power Supply of primary-side-control.

Background technology

The Switching Power Supply of primary-side-control can adopt the assists winding of transformator to obtain the feedback letter related to output voltage Number, thus control circuit can be arranged on the former limit of transformator, and simplify signal feedback path.The switch electricity of primary-side-control Source easily forms modular integrated circuit, has been widely used in each of mobile phone, panel computer and portable electronic device Charge power supply is planted, and is used in the power supply of driven for emitting lights diode (LED).

In further improved Switching Power Supply, the voltage that assists winding is produced is applied not only to provide feedback signal, and Using the power supply for being used for control chip after diode rectification.However, the diode of assists winding and its connection will cause circuit The increase of cost.Additionally, for the demand for meeting signal feedback, the number of turn of assists winding needs to match with the secondary number of turn.For Meet the demand that control chip is powered, the voltage at assists winding two ends also needs to the pressure parameter request for meeting control chip. Therefore, when being powered using assists winding, the VD of LED drive circuit is controlled the limit of the pressure parameter of chip System, it is difficult to provide Width funtion output, so as to be unfavorable for the compatibility of LED drive circuit.

Therefore, it is desirable to the Switching Power Supply of primary-side-control is further improved, to save assists winding and the improvement of transformator The power supply circuits of former limit are reducing circuit cost.

Utility model content

In view of this, the purpose of this utility model is to provide a kind of Switching Power Supply of the primary-side-control without assists winding, Secondary voltage is sensed to provide the feedback signal of secondary voltage by primary side winding, and spike electricity is absorbed in power supply circuits Pressure, so as to save assists winding and absorption circuit, reduces peripheral cell cost.

According to one side of the present utility model, there is provided a kind of Switching Power Supply of primary-side-control, including：Transformator, including original Side winding and vice-side winding；First switch pipe, it is defeated that the first switch pipe is connected in series in DC voltage with the primary side winding Enter between end and ground, the electric current of the first switch pipe to the primary side winding is formed during the conducting of the first switch pipe Path；Current sampling resistor, is connected between the first switch pipe and the primary side winding, for obtain sign flow through described The current sampling signal of the electric current of first switch pipe；Voltage feedback circuit, is connected to the first end and second of the primary side winding Between end, for obtaining the voltage feedback signal of the original edge voltage for characterizing the primary side winding；Control circuit, according to the electric current Sampled signal and the voltage feedback signal produce the drive signal of the first switch pipe, to control the first switch pipe Conducting and disconnection；And power supply circuits, it is connected between the first end of the primary side winding and the second end, for for the control Circuit produces control voltage, and wherein, the first end of the vice-side winding is connected to the first switch pipe, and the second end is grounded, institute There is feeder ear and floating ground terminal, the floating ground terminal to be connected to the first end of the primary side winding, the feeder ear to state control circuit For receiving supply voltage, the floating ground terminal is used for receiving floating earth signal, the control circuit from the primary side winding first End obtains the current sampling signal, and the power supply circuits are additionally operable to absorb the first switch pipe alternate conduction and produce when disconnecting Raw peak voltage, so that suppress to disturb.

Preferably, during the disconnection of the first switch pipe, the original edge voltage of the primary side winding be the secondary around The induced voltage of the secondary voltage of group.

Preferably, also include：Rectifier bridge, for being transformed into DC pulse by the alternating voltage that outside alternating current power supply is provided Voltage；And input capacitance, for DC pulse moving voltage filtering to produce DC input voitage, the first of the input capacitance End is grounded as the DC voltage input end, the second end.

Preferably, also include：Fly-wheel diode, the anode of the fly-wheel diode are connected to the first of the vice-side winding End；And output capacitance, the output capacitance is connected to the second end of the negative electrode of the fly-wheel diode and the vice-side winding Between, wherein, the two ends of the output capacitance provide the output voltage of the Switching Power Supply.

Preferably, the power supply circuits include being sequentially connected in series between the first end of the primary side winding and the second end The first electric capacity, the second electric capacity and the first diode, and the first resistor being connected in parallel with second electric capacity, wherein, institute The anode for stating the first diode is connected to the second end of the primary side winding, and negative electrode is connected to second electric capacity, and described first The intermediate node of electric capacity and second electric capacity is connected to the feeder ear.

Preferably, during the conducting of the first switch pipe, the first end of the primary side winding is the just the described 1st Pole pipe is not turned on, and first electric capacity is in discharge condition, during the disconnection of the first switch pipe, the primary side winding First end is negative, first diode current flow, first electric capacity and second electric capacity is charged using induced voltage, institute State power supply circuits to power for the control circuit using the alternating charging and discharging of first electric capacity, the power supply circuits are in institute During stating the conducting of first switch pipe, discharge to absorb peak voltage using second electric capacity via the first resistor.

Preferably, also include second resistance, the second resistance is connected to the DC voltage input end and the centre Between node, so as to the startup stage in the Switching Power Supply is charged to first electric capacity using DC input voitage, to carry Supply voltage for the control circuit.

Preferably, also include that high voltage startup module, the high voltage startup module include being connected to the DC voltage input The input at end, and it is respectively connecting to the first outfan and second output of the first switch pipe and the intermediate node End, so as to the startup stage in the Switching Power Supply is charged to first electric capacity using DC input voitage, described to provide The supply voltage of control circuit.

Preferably, the high voltage startup module includes：Second switch pipe, the first end of the second switch pipe and the second end The input and first outfan is respectively connecting to, control end is connected to the feeder ear；Transistor, the transistor First end and the second end be respectively connecting to the input and the feeder ear；And power control module, it is connected to described Between the control end of feeder ear and the transistor, for producing drive signal to control the crystal according to the supply voltage The conducting state of pipe, wherein, in the startup stage of the Switching Power Supply, the second switch pipe is off-state, the crystal Manage as conducting state, after the startup of the Switching Power Supply is completed, the second switch pipe is conducting state, the transistor For off-state.

Preferably, the voltage feedback circuit includes the potential-divider network of the multiple resistance compositions being connected in series, the voltage Feedback signal is the voltage division signal of the floating earth signal.

Preferably, the control circuit includes：Constant-current control module, the constant-current control module receive the current sample Signal, the voltage feedback signal, and produce and the control signal with dutycycle；And drive module, from the constant current Control module receives the control signal, and produces the drive signal of the first switch pipe.

Preferably, the compensating module that compensate end connection outside of the constant-current control module via the control circuit, with Maintain system stability.

Preferably, the compensating module includes electric capacity or the electricity being connected between the compensation end and the floating ground terminal Resistance capacitance compensation network.

Preferably, the first end of the vice-side winding and the second end are respectively hot end and cold end, also, described Second end of primary side winding is Same Name of Ends with the first end of the vice-side winding.

According to another aspect of the present utility model, there is provided a kind of control method of the Switching Power Supply for primary-side-control, institute Stating Switching Power Supply includes that transformator and first switch pipe, the transformator include primary side winding and vice-side winding, and described first opens Primary side winding described in Guan Guanyu is connected in series between DC voltage input end and ground, and methods described includes：Open described first On the current path of primary side winding described in Guan Guanzhi, the current sample letter for characterizing the electric current for flowing through the first switch pipe is obtained Number；Between the first end of the primary side winding and the second end, the voltage for obtaining the original edge voltage for characterizing the primary side winding is anti- Feedback signal；According to the drive signal that the current sampling signal and the voltage feedback signal produce the first switch pipe, with Control the conducting and disconnection of the first switch pipe；And adopt power supply circuits to supply for a part of circuit of the Switching Power Supply Electricity, wherein, during the disconnection of the first switch pipe, disconnects between the primary side winding and the DC voltage input end Connection so that the original edge voltage of the primary side winding is the induced voltage of the secondary voltage of the vice-side winding, and the confession Circuit produces supply voltage according to the original edge voltage, and absorbs the first switch pipe alternate conduction and produce when disconnecting Peak voltage, so as to suppress to disturb.

Preferably, the disconnection of the first switch pipe is caused between the primary side winding and the DC voltage input end Connection disconnects.

Preferably, the power supply circuits include being sequentially connected in series between the first end of the primary side winding and the second end The first electric capacity, the second electric capacity and the first diode, and the first resistor being connected in parallel with second electric capacity, wherein, institute The first electric capacity tension discharge using storage during the conducting of the first switch pipe is stated, in the disconnection of the first switch pipe Period is charged using the induced voltage, and second electric capacity and the first resistor constitute loop, in the first switch pipe Conducting moment and disconnect transient absorption peak voltage.

Preferably, first diode is not turned on during the conducting of the first switch pipe, in the first switch Turn on during the disconnection of pipe.

According to the Switching Power Supply of the primary-side-control of embodiment of the present utility model, using floating ground control model, open first The off-state of pipe is closed, and the original edge voltage at primary side winding two ends is the feedback letter that secondary voltage is produced to be sensed by primary side winding Number, such that it is able to save for providing the assists winding of feedback signal, the control of switching tube is realized, to obtain expected output electricity Pressure and/or output current.Further, power supply circuits produce supply voltage using original edge voltage, and in absorption described first The peak voltage produced when switching tube alternate conduction and disconnection, so that suppress to disturb.

Further, since the power supply mode need not use assists winding, so as to there is no the inside electricity due to Switching Power Supply Problem of the running voltage limit switch power supply on road to the output voltage range of externally fed, it is possible to achieve wide output voltage, carries The compatibility of high whole machine.

In a preferred embodiment, the power supply circuits include being sequentially connected in series the primary side winding first end and The first electric capacity, the second electric capacity and the first diode between second end, and the first electricity being connected in parallel with second electric capacity Resistance, can just constitute current supply circuit and absorption circuit using three elements.The program causes be that primary circuit is arranged specially Power supply circuits and absorption circuit, such that it is able to simplify the circuit structure of Switching Power Supply, reduce electronic component and further drop Low cost.

Description of the drawings

By description referring to the drawings to this utility model embodiment, of the present utility model above-mentioned and other mesh , feature and advantage will be apparent from, in the accompanying drawings：

Fig. 1 illustrates the schematic block circuit diagram of the Switching Power Supply of the primary-side-control according to prior art.

Fig. 2 illustrates the schematic block circuit diagram of the Switching Power Supply of the primary-side-control according to this utility model first embodiment.

Fig. 3 illustrates the schematic block circuit diagram of the Switching Power Supply of the primary-side-control according to this utility model second embodiment.

Fig. 4 illustrates the schematic block circuit diagram of the high voltage startup module adopted in the Switching Power Supply shown in Fig. 3.

Specific embodiment

This utility model is more fully described hereinafter with reference to accompanying drawing.In various figures, identical element is using similar Reference representing.For the sake of clarity, the various pieces in accompanying drawing are not necessarily to scale.Furthermore, it is possible to not shown Part known to some.

Describe hereinafter many specific details of the present utility model, the structure of such as device, material, size, place Science and engineering skill and technology, to be more clearly understood that this utility model.But just as the skilled person will understand, This utility model can not be realized according to these specific details.

This utility model can be presented in a variety of manners, some of them example explained below.

Fig. 1 illustrates the schematic block circuit diagram of the Switching Power Supply of the primary-side-control according to prior art.The Switching Power Supply 100 Including transformator T1, and positioned at transformator T1 former limit rectifier bridge 110, power factor correcting (PFC) control circuit 120, Voltage feedback circuit 130, startup and power supply circuits 140, input capacitance Cin, compensating electric capacity C2, switching tube M1, absorption circuit 160th, current sampling resistor Rs, and positioned at transformator T1 secondary sustained diode 6 and output capacitance Cout.

Rectifier bridge 110 includes diode D1 to D4.Two inputs of rectifier bridge 110 are received from outside alternating current power supply and are handed over Stream input voltage.Input capacitance Cin is connected between two outfans of rectifier bridge 110, so as to provide DC input voitage Vin.Primary side winding NP of transformator T1, switching tube M1 and current sampling resistor Rs are sequentially connected in series the height electricity in input capacitance Cin Between position end and ground.The Same Name of Ends of primary side winding NP is connected to the drain electrode of switching tube M1.Current sampling resistor Rs is connected to switch Between the source electrode and ground of pipe M1, the current sampling signal of the electric current for flowing through switching tube M1 for sign is obtained.

Absorption circuit 160 includes electric capacity C4, resistance R7 and diode D7.Electric capacity C4 and diode D7 are connected in series in transformation The two ends of primary side winding NP of device T1, the anode of wherein diode D7 are connected to the Same Name of Ends of primary side winding NP, and anode is connected to Electric capacity C4.Further, resistance R7 and C4 is connected in parallel.Moment is disconnected in switching tube M1, the energy that accumulates in primary side winding NP Electric capacity C4 can be charged by diode D7, electric capacity C4 is discharged via resistance R7 after charging to peak value.Opening Close pipe M1 conducting moments, electric capacity C4 electric discharges are remained unfulfilled, and apply forward voltage at primary side winding NP two ends.Therefore, absorption circuit 160 peak voltages that can be eliminated switching tube M1 alternate conductions and produce when disconnecting, so that suppress to disturb.

Voltage feedback circuit 130 includes assists winding NA of transformator T1, resistance R2 and R3.Resistance R2 and R3 are connected in series Between the Same Name of Ends and ground of assists winding NA, so as to constitute potential-divider network, it is used in the intermediate node of resistance R2 and R3 Characterize the voltage feedback signal of transformer secondary voltage.

Start and power supply circuits 140 include resistance R1, electric capacity C1 and diode D5.Resistance R1 and electric capacity C1 are connected in series Between the hot end and ground of input capacitance Cin.DC input voitage Vin is charged to electric capacity C1 via resistance R1, from And supply voltage VCC is provided in the startup stage of Switching Power Supply for PFC control circuit.The anode of diode D5 be connected to auxiliary around The Same Name of Ends of group NA, negative electrode is connected to the intermediate node of resistance R1 and electric capacity C1, so as to the normal work stage in Switching Power Supply Supply voltage VCC is provided for PFC control circuit.

PFC control circuit 120 has drive end DRV, compensation end COMP and multiple inputs.The confession of PFC control circuit 120 Electric end VCC receives supply voltage, and input CS receives current sampling signal, input FB receiving voltage feedback signals.PFC is controlled The drive end DRV of circuit 120 is connected to the control end of switching tube M1, to provide the drive signal of switching tube M1.Compensating electric capacity C2 It is connected between the compensation end COMP of PFC control circuit 120 and ground, for maintaining stablizing for system.

PFC control circuit 120 include PFC and constant-current control module 121, drive module 122 and under-voltage locking (UVLO) and Base modules 126.PFC and constant-current control module 121 receive current sampling signal, voltage feedback signal, via compensation end COMP Externally connected compensating electric capacity C2, and drive module 122 is connected to, so as to produce the drive signal of switching tube M1.UVLO And base modules 126 obtain supply voltage via feeder ear VCC, and produce the power supply electricity needed for PFC control circuit 120 works Pressure and reference voltage.

In the secondary of transformator T1, sustained diode 6 and output capacitance Cout are connected to the vice-side winding NS of transformator T1 Two ends.The anode of sustained diode 6 is connected to the Same Name of Ends of vice-side winding NS, and negative electrode is connected to the one of output capacitance Cout End.Output voltage Vout is produced at the two ends of output capacitance Cout.In this example, the load of Switching Power Supply 100 is LED, It is connected between the two ends of output capacitance Cout.

With reference to Fig. 1, in the normal work stage of Switching Power Supply 100,120 controlling switch pipe M1 of PFC control circuit alternatings are led On and off is opened.

During the conducting of switching tube M1, PFC and constant-current control module 121 produce drive signal for high level.Transformator The primary current of T1 is begun to ramp up by zero, and current sampling signal rises, and voltage feedback signal is low level.PFC and current constant control Module 121 receives current sampling signal and voltage feedback signal, obtained according to voltage feedback signal fly-wheel diode conducting when Between.Then, the ON time of the electric current and fly-wheel diode of switching tube M1 is flowed through by detection, calculates output current Iout.When the ON time Ton of switching tube M1 reaches the ON time of system requirements, PFC and constant-current control module 121 are produced Raw drive signal is low level so that switching tube M1 is changed into off-state from conducting state.During the disconnection of switching tube M1, Transformator T1 is discharged by sustained diode 6, by energy conduction to outfan.The secondary voltage of transformator T1 is gradually reduced.Whole Individual system is controlled by loop, reaches constant output current by detecting current sampling signal and voltage feedback signal, and And have higher power factor value.

During normal circuit operation shown in Fig. 1, power pack is by assists winding NA and diode D5, electric capacity C1 to PFC Control circuit 120 is powered.Also, the input FB of PFC control circuit 120 is examined by assists winding NA and divider resistance R2, R3 Slowdown monitoring switch signal, for PFC control circuit.Therefore, in such a system, assists winding NA of transformator T1 is essential, while For power supply and signal detection.

As the assists winding of transformator can take certain cost in production, diode D5 and startup resistance R1 also can There is certain cost, therefore, cause the increasing of circuit cost for the power supply of PFC control circuit 120 using assists winding NA of transformator T1 Plus.Additionally, in order to provide the voltage feedback signal corresponding with transformer secondary voltage, the number of turn of the assists winding of transformator is needed To match with the secondary number of turn.The supply voltage of PFC control circuit 120 must be in predetermined operating voltage range.As a result, transformation The secondary voltage of device is also restrained.Correspondingly, the voltage range of the output voltage Vout of whole Switching Power Supply 100 is also limited System, so as to obtain wide-voltage range, is unfavorable for the product of compatible difference output voltage specification.

Fig. 2 illustrates the schematic block circuit diagram of the Switching Power Supply of the primary-side-control according to this utility model first embodiment. The Switching Power Supply 200 includes transformator T1, and the rectifier bridge 110, power factor correcting (PFC) of the former limit positioned at transformator T1 Control circuit 220, voltage feedback circuit 230, power supply circuits 240, input capacitance Cin, compensating electric capacity C2, switching tube M1, electric current Sampling resistor Rs, and positioned at transformator T1 secondary sustained diode 6 and output capacitance Cout.

As shown in Fig. 2 compared to Figure 1, the Switching Power Supply 200 of the embodiment eliminates assists winding NA of transformator T1, And the control circuit using power supply circuits 240 for former limit is powered.

Rectifier bridge 110 includes diode D1 to D4.Two inputs of rectifier bridge 110 are received from outside alternating current power supply and are handed over Stream input voltage, and produce DC pulse moving voltage between the two outputs.Input capacitance Cin is connected to rectifier bridge 110 Between two outfans, so as to filter to produce DC input voitage Vin to DC pulse moving voltage.The first of output capacitance Cin Used as DC voltage input end, the second end is grounded at end.Switching tube M1, current sampling resistor Rs, primary side winding NP of transformator T1 It is sequentially connected in series between DC voltage input end and ground.One end of current sampling resistor Rs is connected to the source electrode of switching tube M1, separately One end is connected to the different name end of primary side winding NP, obtains the current sampling signal of the electric current for flowing through switching tube M1 for sign.

Voltage feedback circuit 230 includes resistance R2 and R3.Resistance R2 and R3 be connected in series in primary side winding different name end and Between ground, so as to constitute potential-divider network, obtain for characterizing the electricity of primary voltage of transformer in the intermediate node of resistance R2 and R3 Pressure feedback signal.

Power supply circuits 240 include resistance R1, electric capacity C1, electric capacity C4, resistance R7 and diode D7.Electric capacity C1, electric capacity C4 and Diode D7 is connected in series in the two ends of primary side winding NP of transformator T1, and the anode of wherein diode D7 is connected to primary side winding The Same Name of Ends of NP, anode are connected to electric capacity C4.Further, resistance R7 and C4 is connected in parallel.

Resistance R1 and electric capacity C1 are connected in series between DC voltage input end and floating ground terminal GND.Opening in Switching Power Supply Dynamic stage, DC input voitage Vin charge to electric capacity C1 via resistance R1, so as to produce supply voltage VCC at electric capacity C1 two ends, It is supplied to PFC control circuit 220.

In the off-state of switching tube M1, the different name end of primary side winding NP is cold end.Accumulation in primary side winding NP Energy can be charged to electric capacity C1 and electric capacity C4 by diode D7, and electric capacity C4 enters via resistance R7 after charging to peak value Row electric discharge.In the conducting state of switching tube M1, the different name end of primary side winding NP is hot end, off-state at diode D7. Electric capacity C1 is discharged via feeder ear VCC, so as to power for PFC control circuit 220.

The power supply circuits 240 include the absorption circuit shown in Fig. 1.Moment is disconnected in switching tube M1, via diode D7 pair Electric capacity C1 and C4 charge.Moment is turned in switching tube M1, the electric discharge of electric capacity C4 is remained unfulfilled, just applied at primary side winding NP two ends To voltage.Therefore, the peak voltage that the power supply circuits 240 can eliminate switching tube M1 alternate conductions and produce when disconnecting, so as to Suppress interference.

Therefore, power supply circuits 240 have power supply concurrently and suppress the function of peak voltage, without the inside for former limit for adding Plus the element such as any additional diode and electric capacity.

PFC control circuit 220 has drive end DRV, compensation end COMP, floating ground terminal GND and multiple inputs.PFC is controlled The feeder ear VCC of circuit 220 receives supply voltage, and input CS receives current sampling signal, and input FB receiving voltages are fed back Signal.Floating ground terminal GND of PFC control circuit 220 is connected to the different name end of primary side winding NP so that PFC control circuit 220 is adopted The control mode work of floating ground.The drive end DRV of PFC control circuit 220 is connected to the control end of switching tube M1, to provide switch The drive signal of pipe M1.Compensating electric capacity C2 is connected between the compensation end COMP of PFC control circuit 220 and floating ground terminal GND, is used for Maintenance system is stablized.In alternate embodiments, RC compensation networks can be adopted to replace compensating electric capacity C2.

PFC control circuit 220 includes diode D8, PFC and constant-current control module 221 and drive module 222.Diode D8 Be connected between feeder ear VCC and floating ground terminal GND, for by supply voltage clamper to fixed voltage, it is to avoid overtension is caused Circuit is damaged.PFC and constant-current control module 221 receive current sampling signal, voltage feedback signal, via compensation end COMP connections To outside compensating electric capacity C2, so as to produce and the control signal with dutycycle, the dutycycle and desired output voltage/or Electric current is corresponding.PFC and constant-current control module 221 are connected to drive module 222, and the latter produces switching tube M1 according to control signal Drive signal.

Preferably, PFC control circuit 220 can also include under-voltage latch (UVLO) and base modules 226.UVLO and benchmark Module 226 obtains supply voltage via feeder ear VCC, and produces supply voltage and base needed for PFC control circuit 220 works Quasi- voltage.

In the secondary of transformator T1, sustained diode 6 and output capacitance Cout are connected to the vice-side winding NS of transformator T1 Two ends.The anode of sustained diode 6 is connected to the Same Name of Ends of vice-side winding NS, and negative electrode is connected to the one of output capacitance Cout End.Output voltage Vout is produced at the two ends of output capacitance Cout.In this example, the load of Switching Power Supply 200 is LED, It is connected between the two ends of output capacitance Cout.

With reference to Fig. 2, in the normal work stage of Switching Power Supply 200,220 controlling switch pipe M1 of PFC control circuit alternatings are led On and off is opened.

During the conducting of switching tube M1, PFC and constant-current control module 221 produce drive signal for high level.Switching tube The drain electrode of M1 is low level.Electric current flows through primary side winding NP of switching tube M1, current sampling resistor Rs and transformator T1 successively.Cause And, transformator T1 stores energy.The primary current of transformator T1 is begun to ramp up by zero, and current sampling signal rises.Meanwhile, PFC Floating ground terminal GND of control circuit 220 is just, is close to DC input voitage Vin.Voltage feedback signal relative to floating ground terminal GND is Negative.

PFC and constant-current control module 121 receive current sampling signal and voltage feedback signal, are obtained according to voltage feedback signal Obtain the ON time of fly-wheel diode.Then, by detecting during the conducting of electric current and fly-wheel diode for flowing through switching tube M1 Between, calculate output current Iout.When the ON time Ton of switching tube M1 reaches the ON time of system requirements, PFC and perseverance It is low level that flow control module 121 produces drive signal so that switching tube M1 is changed into off-state from conducting state.

During the disconnection of switching tube M1, the discharge current that the vice-side winding NS of transformator T1 is provided flows through afterflow two successively Pole pipe D6, output capacitance Cout and load LED.That is, transformator T1 is discharged by sustained diode 6, by energy conduction to defeated Go out end.The secondary voltage of transformator T1 is gradually reduced.Meanwhile, primary side winding NP of transformator T1 produces the sensing of vice-side winding NS Voltage so that floating ground terminal GND of PFC control circuit 220 is negative, is close to direct-current ground potential.Voltage feedback signal is relative to floating End GND is the ON time that just can detecting fly-wheel diode by voltage feedback signal.Whole system is adopted by detecting electric current Sample signal and voltage feedback signal, are controlled by loop, are reached constant output current, and are had higher power factor Value.

Power supply circuits 240 are used for powering to PFC control circuit 220.During system worked well, when switching tube M1 is turned on When, floating ground terminal GND of PFC control circuit 220 is for just.Now, the diode D7 of power supply circuits 240 is not turned on, and system is by electricity The energy for holding C1 accumulations is powered to PFC control circuit 220.During system worked well, when switching tube M1 disconnects, transformator Floating ground terminal GND at the different name end of primary side winding NP of T1, i.e. PFC control circuit 220 is negative.Ground due to the former limit of transformator T1 For no-voltage, therefore, the voltage Vnp=N*Vns at the primary side winding NP two ends of transformator T1, wherein, circles of the N for transformator T1 Than output voltages of the Vns for the vice-side winding NS two ends of transformator T1.Voltage Vnp is filled for electric capacity C1 and C4 via diode D7 Electricity.Meanwhile, the inside of PFC control circuit 220 provides a clamp voltage using diode D8, for limiting supply voltage most High voltage.

Therefore, during system worked well, power supply circuits 240 are periodically charged and discharged to electric capacity C1, from And realize the power supply to PFC control circuit 220.

Fig. 3 illustrates the schematic block circuit diagram of the Switching Power Supply of the primary-side-control according to this utility model second embodiment. The Switching Power Supply 300 includes transformator T1, and the rectifier bridge 110, power factor correcting (PFC) of the former limit positioned at transformator T1 Control circuit 320, voltage feedback circuit 330, power supply circuits 340, input capacitance Cin, compensating electric capacity C2, switching tube M1, electric current Sampling resistor Rs, and positioned at transformator T1 secondary sustained diode 6 and output capacitance Cout.

As shown in figure 3, compared to Figure 1, the Switching Power Supply 300 of the embodiment eliminates assists winding NA of transformator T1, And the control circuit using power supply circuits 340 for former limit is powered.Compared with Fig. 2, the Switching Power Supply 300 of the embodiment is further Including high-voltage starting circuit 310, to replace the resistance R1 charged in the startup stage of Switching Power Supply as electric capacity C1.

For simplicity's sake, hereafter second embodiment is no longer described in detail with identical circuit module in first embodiment, and only The difference of the two is described.

High-voltage starting circuit 310 is connected between the first end of electric capacity Cin and switching tube M1, for producing in system electrification Raw supply voltage.The outfan of the high-voltage starting circuit 310 is connected to the feeder ear VCC of PFC control circuit 320.

Power supply circuits 340 include electric capacity C1, electric capacity C4, resistance R7 and diode D7.Electric capacity C1, electric capacity C4 and diode D7 The two ends of primary side winding NP of transformator T1 are connected in series in, the anode of wherein diode D7 is connected to the of the same name of primary side winding NP End, anode are connected to electric capacity C4.Further, resistance R7 and C4 is connected in parallel the feeder ear VCC of PFC control circuit 320.

The power supply circuits 340 include the absorption circuit shown in Fig. 1.Moment is disconnected in switching tube M1, via diode D7 pair Electric capacity C1 and C4 charge.Moment is turned in switching tube M1, the electric discharge of electric capacity C4 is remained unfulfilled, just applied at primary side winding NP two ends To voltage.Therefore, the peak voltage that the power supply circuits 340 can eliminate switching tube M1 alternate conductions and produce when disconnecting, so as to Suppress interference.

Therefore, power supply circuits 340 have power supply concurrently and suppress the function of peak voltage, without the inside for former limit for adding Plus the element such as any additional diode and electric capacity.

PFC control circuit 320 includes diode D8, PFC and constant-current control module 321, drive module 322.Diode D8 Be connected between feeder ear VCC and floating ground terminal GND, for by supply voltage clamper to fixed voltage, it is to avoid overtension is caused Circuit is damaged.PFC and constant-current control module 321 receive current sampling signal, voltage feedback signal, via compensation end COMP connections To outside compensating electric capacity C2, so as to produce and the control signal with dutycycle, the dutycycle and desired output voltage/or Electric current is corresponding.PFC and constant-current control module 321 are connected to drive module 322, and the latter produces switching tube M1 according to control signal Drive signal.

Preferably, PFC control circuit 320 can also include UVLO and base modules 326.UVLO and base modules 326 are passed through Supply voltage is obtained by feeder ear VCC, and produces supply voltage and reference voltage needed for PFC control circuit 220 works.

In the secondary of transformator T1, sustained diode 6 and output capacitance Cout are connected to the vice-side winding NS of transformator T1 Two ends.The anode of sustained diode 6 is connected to the Same Name of Ends of vice-side winding NS, and negative electrode is connected to the one of output capacitance Cout End.Output voltage Vout is produced at the two ends of output capacitance Cout.In this example, the load of Switching Power Supply 300 is LED, It is connected between the two ends of output capacitance Cout.

With reference to Fig. 3, in the normal work stage of Switching Power Supply 300,320 controlling switch pipe M1 of PFC control circuit alternatings are led On and off is opened.

During the startup of Switching Power Supply 300, high voltage startup module 310 starts for system electrification.

During the normal work of Switching Power Supply 300, power supply circuits 340 are used for providing power supply to PFC control circuit 320. When switching tube M1 is turned on, floating ground terminal GND of PFC control circuit 320 is for just.Now, the diode D7 of power supply circuits 340 does not lead Logical, the energy that system is accumulated by electric capacity C1 is powered to PFC control circuit 320.When switching tube M1 disconnects, the original of transformator T1 Floating ground terminal GND at the different name end of side winding NP, i.e. PFC control circuit 320 is negative.As the ground of the former limit of transformator T1 is zero electricity Pressure, therefore, the voltage Vnp=N*Vns at the primary side winding NP two ends of transformator T1, wherein, the turn ratioes of the N for transformator T1, Vns is The output voltage at the vice-side winding NS two ends of transformator T1.Voltage Vnp charges for electric capacity C1 via resistance R4 and diode D7.With When, the inside of PFC control circuit 320 provides a clamp voltage using diode D8, for limiting the highest electricity of supply voltage Pressure.

Therefore, during system worked well, power supply circuits 340 are periodically charged and discharged to electric capacity C1, from And realize the power supply to PFC control circuit 320.

Fig. 4 illustrates the schematic block circuit diagram of the high voltage startup module adopted in the Switching Power Supply shown in Fig. 3.High pressure is opened Dynamic model block 310 includes power control module 311, switching tube M2, transistor M3.Switching tube M2 is connected in series with switching tube M1, its First end is connected to the first end of input capacitance Cin, and its second end is connected to the first end of switching tube M1.The control of switching tube M2 End is connected to feeder ear VCC.The second end connection sampling resistor Rs of switching tube M1.The input connection of power control module 311 To feeder ear VCC, its outfan is connected to the grid of transistor M3, for controlling its conducting state.

Switching tube M1, M2 and transistor M3 can be selected from mos field effect transistor and bipolar crystalline substance One kind of body pipe.In the case of switching tube M1, M2 and transistor M3 are turned on, electric current flows to the second end from first end.For example, open It is N-type mos field effect transistor respectively to close pipe M1, M2 and transistor M3, the first end, the second end and Control end is drain electrode, source electrode and grid respectively.

During the startup of Switching Power Supply 300, transistor M3 is turned on, and switching tube M2 disconnects.Switching tube M1 and DC pulse Connection between voltage disconnects, and primary side winding NP of transformator T1 is not to vice-side winding NS transmission energies.High voltage startup module 310 It is used for charging electric capacity C1 by DC pulse moving voltage so that the voltage of feeder ear VCC rises very rapidly up to PFC control circuit 320 Normal working voltage.After the startup of Switching Power Supply 300 is completed, correspondingly, the control terminal voltage of switching tube M2 is also raised, and is made Obtain switching tube M2 conductings.Switching tube M1 is connected with DC pulse moving voltage, and the driving letter provided in PFC control circuit 320 Number control under conducting and disconnect, primary side winding NP of transformator T1 is to vice-side winding NS transmission energies.System passes through transformator Charging of the primary side winding of T1 to electric capacity C1, continues as PFC control circuit 320 and provides piezoelectric voltage.

It should be noted that herein, such as first and second or the like relational terms are used merely to a reality Body or operation are made a distinction with another entity or operation, and are not necessarily required or implied these entities or deposit between operating In any this actual relation or order.And, term " including ", "comprising" or its any other variant are intended to Nonexcludability includes, so that a series of process, method, article or equipment including key elements not only includes that those will Element, but also other key elements including being not expressly set out, or also include for this process, method, article or equipment Intrinsic key element.In the absence of more restrictions, the key element for being limited by sentence "including a ...", it is not excluded that Also there is other identical element in process, method, article or equipment including the key element.

According to embodiment of the present utility model as described above, these embodiments do not have all of details of detailed descriptionthe, Also it is only described specific embodiment not limit the utility model.Obviously, as described above, a lot of modifications and change can be made Change, including but not limited to the modification of COMP end compensating network building forms, the change to the local structure of circuit, to components and parts Type or model replacement.This specification is chosen and specifically describes these embodiments, is new in order to preferably explain this practicality The principle and practical application of type, so that skilled artisan can well using this utility model and in this reality Used with the modification on novel foundation.This utility model is only limited by claims and its four corner and equivalent.

Claims

1. a kind of Switching Power Supply of primary-side-control, it is characterised in that include：

Transformator, including primary side winding and vice-side winding；

First switch pipe, the first switch pipe and the primary side winding are connected in series between DC voltage input end and ground, The current path of the first switch pipe to the primary side winding is formed during the conducting of the first switch pipe；

Current sampling resistor, is connected between the first switch pipe and the primary side winding, for obtain sign flow through described The current sampling signal of the electric current of first switch pipe；

Voltage feedback circuit, is connected between the first end of the primary side winding and the second end, characterizes the former limit for obtaining The voltage feedback signal of the original edge voltage of winding；

Control circuit, is connected with the current sampling resistor and the voltage feedback circuit, according to the current sampling signal The drive signal of the first switch pipe is produced with the voltage feedback signal, leads on and off with control the first switch pipe Open；And

Power supply circuits, are connected between the first end of the primary side winding and the second end, for producing control for the control circuit Voltage processed,

Wherein, the first end of the vice-side winding is connected to the first switch pipe, and the second end is grounded,

The control circuit has feeder ear and floating ground terminal, and the floating ground terminal is connected to the first end of the primary side winding, described Feeder ear is used for receiving supply voltage, and the floating ground terminal is used for receiving floating earth signal,

The control circuit obtains the current sampling signal from the first end of the primary side winding,

The power supply circuits are additionally operable to the peak voltage for absorbing the first switch pipe alternate conduction and producing when disconnecting, so as to press down System interference.

2. Switching Power Supply according to claim 1, it is characterised in that during the disconnection of the first switch pipe, described The original edge voltage of primary side winding is the induced voltage of the secondary voltage of the vice-side winding.

3. Switching Power Supply according to claim 1, it is characterised in that also include：

Rectifier bridge, for being transformed into DC pulse moving voltage by the alternating voltage that outside alternating current power supply is provided；And

Input capacitance, is connected with the rectifier bridge, for filtering DC pulse moving voltage to produce DC input voitage, institute The first end of input capacitance is stated as the DC voltage input end, the second end is grounded.

4. Switching Power Supply according to claim 1, it is characterised in that also include：

Fly-wheel diode, the anode of the fly-wheel diode are connected to the first end of the vice-side winding；And

Output capacitance, the output capacitance be connected to the negative electrode of the fly-wheel diode and the vice-side winding the second end it Between,

Wherein, the two ends of the output capacitance provide the output voltage of the Switching Power Supply.

5. Switching Power Supply according to claim 2, it is characterised in that the power supply circuits include being sequentially connected in series in institute State the first electric capacity between the first end of primary side winding and the second end, the second electric capacity and the first diode, and with described second The first resistor that electric capacity is connected in parallel,

Wherein, the anode of first diode is connected to the second end of the primary side winding, and negative electrode is connected to second electricity Hold, the intermediate node of first electric capacity and second electric capacity is connected to the feeder ear.

6. Switching Power Supply according to claim 5, it is characterised in that during the conducting of the first switch pipe, described For just, first diode is not turned on, first electric capacity is in discharge condition to the first end of primary side winding,

During the disconnection of the first switch pipe, the first end of the primary side winding is negative, first diode current flow, profit First electric capacity and second electric capacity are charged with induced voltage,

The power supply circuits are powered for the control circuit using the alternating charging and discharging of first electric capacity,

The power supply circuits are put via the first resistor using second electric capacity during the conducting of the first switch pipe Electricity is absorbing peak voltage.

7. Switching Power Supply according to claim 5, it is characterised in that also include second resistance, the second resistance connection Between the DC voltage input end and the intermediate node, so as to the startup stage in the Switching Power Supply is defeated using direct current Enter voltage to charge first electric capacity, to provide the supply voltage of the control circuit.

8. Switching Power Supply according to claim 5, it is characterised in that also include high voltage startup module, the high voltage startup Module includes the input for being connected to the DC voltage input end, and be respectively connecting to the first switch pipe and described in First outfan and the second outfan of intermediate node, so that utilize DC input voitage in the startup stage of the Switching Power Supply First electric capacity is charged, to provide the supply voltage of the control circuit.

9. Switching Power Supply according to claim 8, it is characterised in that the high voltage startup module includes：

Second switch pipe, the first end of the second switch pipe and the second end are respectively connecting to the input and described first defeated Go out end, control end is connected to the feeder ear；

Transistor, the first end of the transistor and the second end are respectively connecting to the input and the feeder ear；And

Power control module, is connected between the control end of the feeder ear and the transistor, for according to the power supply electricity Pressure produces drive signal to control the conducting state of the transistor,

Wherein, in the startup stage of the Switching Power Supply, the second switch pipe is off-state, and the transistor is conducting shape State, after the startup of the Switching Power Supply is completed, the second switch pipe is conducting state, and the transistor is to disconnect shape State.

10. Switching Power Supply according to claim 2, it is characterised in that the voltage feedback circuit includes being connected in series The potential-divider network of multiple resistance compositions, the voltage feedback signal is the voltage division signal of the floating earth signal.

11. Switching Power Supplies according to claim 2, it is characterised in that the control circuit includes：

Constant-current control module, the constant-current control module receive the current sampling signal, the voltage feedback signal, and produce The raw control signal with dutycycle；And

Drive module, receives the control signal from the constant-current control module, and produces the driving of the first switch pipe Signal.

12. Switching Power Supplies according to claim 11, it is characterised in that the constant-current control module is via the control electricity Compensating module outside the compensation end connection on road, to maintain system stability.

13. Switching Power Supplies according to claim 12, it is characterised in that the compensating module includes being connected to the compensation Electric capacity or compensation of resistance and capacitance network between end and the floating ground terminal.

14. Switching Power Supplies according to claim 1, it is characterised in that the first end of the vice-side winding and the second end point Not Wei hot end and cold end, also, the second end of the primary side winding and the first end of the vice-side winding are of the same name End.