CN205509876U - Primary side -controlled switching power supply - Google Patents
Primary side -controlled switching power supply Download PDFInfo
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- CN205509876U CN205509876U CN201620167695.7U CN201620167695U CN205509876U CN 205509876 U CN205509876 U CN 205509876U CN 201620167695 U CN201620167695 U CN 201620167695U CN 205509876 U CN205509876 U CN 205509876U
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- 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
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Abstract
Primary side -controlled switching power supply is disclosed. Primary side -controlled switching power supply includes: the transformer is including primary side winding and vice limit winding, the switch tube, the switch tube with the primary side winding series connection is not between direct current voltage input end and ground, current sample resistance is connected the switch tube with between the primary side winding for obtain the current sample signal, the voltage feedback circuit is connected primary side winding's both ends for obtain voltage feedback signal, control circuit, according to the current sample signal with voltage feedback signal produces the drive signal of switch tube is with control the switching on and break off of switch tube, wherein, control circuit follows the switch tube with first node between the current sample resistance obtains the current sample signal, follows current sample resistance with second node between the primary side winding obtains to float the earth signal. This switching power supply can save auxiliary winding to can realize wide output voltage and reduce cost.
Description
Technical field
This utility model relates 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 use the auxiliary winding of transformator to obtain the feedback signal relevant to output voltage, thus control circuit can be arranged on the former limit of transformator, and simplifies signal feedback path.The Switching Power Supply of primary-side-control easily forms modular integrated circuit, has been widely used in the various charge power supplies of mobile phone, panel computer and portable electronic device, and in the power supply of driven for emitting lights diode (LED).
But, in the Switching Power Supply of primary-side-control, the volume that the auxiliary winding of transformator does not only result in power supply is big, and produces additional cost.If being that control circuit is powered further with auxiliary winding, then the scope of the output voltage of the secondary of transformator also can be controlled the restriction of running voltage of circuit, thus can not realize wide output voltage, is unfavorable for the compatibility of Switching Power Supply.
Therefore, it is desirable to improve the Switching Power Supply of primary-side-control further, to save the auxiliary winding of transformator.
Utility model content
In view of this, the purpose of this utility model is to provide the Switching Power Supply of a kind of primary-side-control without auxiliary winding, by primary side winding sensing secondary voltage to provide the feedback signal of secondary voltage, thus saves auxiliary winding power, reduces peripheral cell cost.
According to one side of the present utility model, it is provided that the Switching Power Supply of a kind of primary-side-control, including: transformator, including primary side winding and vice-side winding；Switching tube, described switching tube and described primary side winding are connected in series between DC voltage input end and ground, form the current path of described switching tube extremely described primary side winding during the conducting of described switching tube；Current sampling resistor, is connected between described switching tube and described primary side winding, for obtaining the current sampling signal characterizing the electric current flowing through described switching tube；Voltage feedback circuit, is connected to the two ends of described primary side winding, for obtaining the voltage feedback signal of the original edge voltage characterizing described primary side winding；Control circuit, the driving signal of described switching tube is produced according to described current sampling signal and described voltage feedback signal, to control conducting and the disconnection of described switching tube, wherein, described control circuit has feeder ear and holds floatingly, it is respectively used to receive supply voltage and floating earth signal, described control circuit obtains described current sampling signal from the primary nodal point between described switching tube and described current sampling resistor, obtains described floating earth signal from the secondary nodal point between described current sampling resistor and described primary side winding.
Preferably, during the disconnection of described switching tube, the original edge voltage of described primary side winding is the induced voltage of the secondary voltage of described vice-side winding.
Preferably, described Switching Power Supply also includes: rectifier bridge, for the alternating voltage that outside alternating current power supply provides is transformed into DC pulse moving voltage；And input capacitance, for filtering DC pulse moving voltage to produce DC input voitage, the first end of described input capacitance is as described DC voltage input end, the second end ground connection.
Preferably, described Switching Power Supply also includes: fly-wheel diode, and the anode of described fly-wheel diode is connected to the first end of described vice-side winding；And output capacitance, described output capacitance is connected between the negative electrode of described fly-wheel diode and the second end of described vice-side winding, and wherein, the two ends of described output capacitance provide the output voltage of described Switching Power Supply.
Preferably, described Switching Power Supply also includes: power supply circuits, described power supply circuits include being connected in series in and described hold floatingly between the first resistance, the first diode and the first electric capacity, wherein, the anode of described first diode is connected to described first resistance, negative electrode is connected to described first electric capacity, and the 3rd node between described first diode and described first electric capacity is connected to described feeder ear.
Preferably, during the conducting of described switching tube, described floating ground end is just, described first diode does not turns on, and described first electric capacity is in discharge condition, during the disconnection of described switching tube, described floating ground end is negative, described first diode current flow, utilizes induced voltage to described first electric capacity charging, and described power supply circuits utilize the alternately charging and discharging of described first electric capacity to be that described control circuit is powered.
Preferably, described Switching Power Supply also includes the second resistance, described second resistance is connected between described DC voltage input end and described 3rd node, thus described Switching Power Supply startup stage utilize DC input voitage to described first electric capacity charging, to provide the supply voltage of described control circuit.
Preferably, described voltage feedback circuit includes the potential-divider network of the multiple resistance composition being connected in series, and described voltage feedback signal is the voltage division signal of described floating earth signal.
Preferably, described control circuit includes: constant-current control module, and described constant-current control module receives described current sampling signal, described voltage feedback signal, and produces and the control signal with dutycycle；And driving module, receive described control signal from described constant-current control module, and produce the driving signal of described switching tube.
Preferably, described constant-current control module is via the compensating module outside the compensation end connection of described control circuit, to maintain system stability.
Preferably, described compensating module include being connected to described compensation end and described hold floatingly between electric capacity or compensation of resistance and capacitance network.
Preferably, described control circuit also includes: high voltage startup module, for described Switching Power Supply startup stage be that described control circuit is powered.
Preferably, first end of described primary side winding is connected to described end and the second end ground connection floatingly, first end of described vice-side winding and the second end are respectively hot end and cold end, and, the second end of described primary side winding and the first end of described vice-side winding are Same Name of Ends.
According to another aspect of the present utility model, the control method of a kind of Switching Power Supply for primary-side-control is provided, described Switching Power Supply includes transformator and switching tube, described transformator includes primary side winding and vice-side winding, described switching tube and described primary side winding are connected in series between DC voltage input end and ground, described method includes: on the current path of described switching tube to described primary side winding, it is thus achieved that characterize the current sampling signal of the electric current flowing through described switching tube；Two ends in described primary side winding, it is thus achieved that characterize the voltage feedback signal of the original edge voltage of described primary side winding；The driving signal of described switching tube is produced according to described current sampling signal and described voltage feedback signal, to control conducting and the disconnection of described switching tube, wherein, during the disconnection of described switching tube, disconnect the connection between described primary side winding and described DC voltage input end so that the original edge voltage of described primary side winding is the induced voltage of the secondary voltage of described vice-side winding.
Preferably, the disconnection of described switching tube makes the connection between described primary side winding and described DC voltage input end disconnect.
Preferably, the a part of circuit using the first electric capacity to be described Switching Power Supply is powered, wherein said first electric capacity is connected between the first end of described primary side winding and the second end, and during the conducting of described switching tube, utilize the tension discharge of storage, utilize described induced voltage to charge during the disconnection of described switching tube.
Preferably, the first diode is used to control the charging and discharging of described first electric capacity, wherein, described first diode and described first capacitances in series are connected between the first end of described primary side winding and the second end, and it is not turned on during the conducting of described switching tube, turns on during the disconnection of described switching tube.
The Switching Power Supply of the primary-side-control according to embodiment of the present utility model, use floating ground control model, by primary side winding sensing secondary voltage to provide the feedback signal of secondary voltage, such that it is able to save the auxiliary winding for providing feedback signal, realize the control of switching tube, to obtain intended output voltage and/or output electric current.
In a preferred embodiment, resistance, diode and electric capacity composition current supply circuit are used.Utilize induced voltage that electric capacity is charged during the disconnection of switching tube, thus realize the power supply of at least some of circuit to Switching Power Supply.The program need not arrange special power supply circuits, such that it is able to simplify the circuit structure of Switching Power Supply, reduces electronic component and reduces cost further.
Additionally, due to this power supply mode need not use auxiliary winding, thus there is not the running voltage limit switch power supply of the internal circuit due to Switching Power Supply to the problem of the output voltage range of externally fed, it is possible to achieve wide output voltage, improve the compatibility of complete machine.
Accompanying drawing explanation
By description to this utility model embodiment referring to the drawings, of the present utility model above-mentioned and other objects, features and advantages 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 the second embodiment.
Detailed description of the invention
It is more fully described this utility model hereinafter with reference to accompanying drawing.In various figures, identical element uses similar reference to represent.For the sake of clarity, the various piece in accompanying drawing is not necessarily to scale.Furthermore, it is possible to not shown part known to some.
Describe hereinafter the specific details of many of the present utility model, the structure of such as device, material, size, process technique and technology, in order to be more clearly understood that this utility model.But the most as the skilled person will understand, this utility model can not be realized according to these specific details.
This utility model can present 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.This Switching Power Supply 100 includes transformator T1, and be positioned at the rectifier bridge 110 on the former limit of transformator T1, power factor correcting (PFC) control circuit 120, voltage feedback circuit 130, start and power supply circuits 140, input capacitance Cin, compensation electric capacity C2, switching tube M1, current sampling resistor Rs, and it is positioned at sustained diode 6 and output capacitance Cout of the secondary of transformator T1.
Rectifier bridge 110 includes diode D1 to D4.Two inputs of rectifier bridge 110 receive AC-input voltage from outside alternating current power supply.Input capacitance Cin is connected between two outfans of rectifier bridge 110, thus provides DC input voitage Vin.Primary side winding NP of transformator T1, switching tube M1 and current sampling resistor Rs are sequentially connected in series between the hot end and ground of input capacitance Cin.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 between source electrode and the ground of switching tube M1, it is thus achieved that for characterizing the current sampling signal of the electric current flowing through switching tube M1.
Voltage feedback circuit 130 includes auxiliary winding NA, resistance R2 and R3 of transformator T1.Resistance R2 and R3 is connected in series between Same Name of Ends and the ground of auxiliary winding NA, thus forms potential-divider network, and the intermediate node at resistance R2 and R3 obtains the voltage feedback signal for characterizing transformer secondary voltage.
Start and power supply circuits 140 include resistance R1, electric capacity C1 and diode D5.Resistance R1 and electric capacity C1 is connected in series between the hot end of input capacitance Cin and ground, for Switching Power Supply startup stage for PFC control circuit provide supply voltage VCC.The anode of diode D5 is connected to assist the Same Name of Ends of winding NA, and negative electrode is connected to resistance R1 and the intermediate node of electric capacity C1, thus is that PFC control circuit provides supply voltage VCC in the normal work stage of Switching Power Supply.
PFC control circuit 120 has drive end DRV, compensates end COMP and multiple input.The input VCC of PFC control circuit 120 receives supply voltage, and input CS receives current sampling signal, and input FB receives voltage feedback signal.The drive end DRV of PFC control circuit 120 is connected to the control end of switching tube M1, to provide the driving signal of switching tube M1.Compensate between compensation end COMP and the ground that electric capacity C2 is connected to PFC control circuit 120, for maintaining stablizing of system.
PFC control circuit 120 includes PFC and constant-current control module 121, drives 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, the compensation electric capacity C2 externally connected via compensating end COMP, and are connected to drive module 122, thus produce the driving signal of switching tube M1.UVLO and base modules 126 obtain supply voltage via input VCC, and produce PFC control circuit 120 and work required supply voltage and reference voltage.
At the secondary of transformator T1, sustained diode 6 and output capacitance Cout are connected to the two ends of the vice-side winding NS of transformator T1.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 one end of output capacitance Cout.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, 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, PFC control circuit 120 controls switching tube M1 alternate conduction and disconnection.
During the conducting of switching tube M1, PFC and constant-current control module 121 produce and drive signal is high level.The primary current of transformator T1 is begun to ramp up by zero, and current sampling signal rises, and voltage feedback signal is low level.PFC and constant-current control module 121 receive current sampling signal and voltage feedback signal, obtain the ON time of fly-wheel diode according to voltage feedback signal.Then, flowed through electric current and the ON time of fly-wheel diode of switching tube M1 by detection, calculate output electric 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 produce and 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 energy conduction to outfan by sustained diode 6.The secondary voltage of transformator T1 is gradually reduced.Whole system, by detection current sampling signal and voltage feedback signal, is controlled by loop, reaches constant output current, and have higher power factor value.
During normal circuit operation shown in Fig. 1, power pack is powered to PFC control circuit 120 by auxiliary winding NA and diode D5, electric capacity C1.Further, the input FB of PFC control circuit 120 detects switching signal, for PFC control circuit by auxiliary winding NA and divider resistance R2, R3.Therefore, in such a system, the auxiliary winding NA of transformator T1 is essential, is simultaneously used for power supply and signal detection.
Also have certain cost owing to the auxiliary winding of transformator can take certain cost, diode D5 and startup resistance R1 when producing, therefore, utilize the auxiliary winding NA of transformator T1 to cause the increase of circuit cost for PFC control circuit 120 power supply.Additionally, in order to provide the voltage feedback signal corresponding with transformer secondary voltage, the number of turn of the auxiliary winding of transformator needs 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, the secondary voltage of transformator is also restrained.Correspondingly, the voltage range of the output voltage Vout of whole Switching Power Supply 100 is also restrained, thus can not obtain wide-voltage range, is unfavorable for the product of compatible different 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.This Switching Power Supply 200 includes transformator T1, and be positioned at the rectifier bridge 110 on the former limit of transformator T1, power factor correcting (PFC) control circuit 220, voltage feedback circuit 230, start and power supply circuits 240, input capacitance Cin, compensation electric capacity C2, switching tube M1, current sampling resistor Rs, and it is positioned at sustained diode 6 and output capacitance Cout of the secondary of transformator T1.
As in figure 2 it is shown, compared to Figure 1, the Switching Power Supply 200 of this embodiment eliminates the auxiliary winding NA of transformator T1.
Rectifier bridge 110 includes diode D1 to D4.Two inputs of rectifier bridge 110 receive AC-input voltage from outside alternating current power supply, and produce DC pulse moving voltage between the two outputs.Input capacitance Cin is connected between two outfans of rectifier bridge 110, thus filters DC pulse moving voltage to produce DC input voitage Vin.First end of output capacitance Cin as DC voltage input end, the second end ground connection.Switching tube M1, current sampling resistor Rs, primary side winding NP of transformator T1 are 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, and the other end is connected to the different name end of primary side winding NP, it is thus achieved that for characterizing the current sampling signal of the electric current flowing through switching tube M1.
Voltage feedback circuit 230 includes resistance R2 and R3.Resistance R2 and R3 is connected in series between different name end and the ground of primary side winding, thus forms potential-divider network, and the intermediate node at resistance R2 and R3 obtains the voltage feedback signal for characterizing primary voltage of transformer.
Start and power supply circuits 240 include resistance R1 and R4, electric capacity C1 and diode D5.Resistance R1 and electric capacity C1 is connected in series in DC voltage input end and floating holds between GND.Switching Power Supply startup stage, DC input voitage Vin via resistance R1 to electric capacity C1 charge, thus electric capacity C1 two ends produce supply voltage VCC, it is provided that to PFC control circuit 220.The anode of diode D5 is connected to the ground via resistance R4, and negative electrode is connected to resistance R1 and the intermediate node of electric capacity C1, thus is that PFC control circuit provides supply voltage VCC in the normal work stage of Switching Power Supply.
PFC control circuit 220 has drive end DRV, compensates end COMP, floating holds GND and multiple input.The input VCC of PFC control circuit 220 receives supply voltage, and input CS receives current sampling signal, and input FB receives voltage feedback signal.The floating ground end GND of PFC control circuit 220 is connected to the different name end of primary side winding NP so that PFC control circuit 220 uses 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 the driving signal of switching tube M1.Compensate electric capacity C2 be connected to the compensation end COMP of PFC control circuit 220 and floating hold between GND, be used for maintaining stablizing of system.In alternate embodiments, RC can be used to compensate network replace compensating electric capacity C2.
PFC control circuit 220 includes diode D8, PFC and constant-current control module 221 and drives module 222.Diode D8 is connected to input VCC and floating holds between GND, for by supply voltage clamper to fixed voltage, it is to avoid overtension causes circuit to damage.PFC and constant-current control module 221 receive current sampling signal, voltage feedback signal, the compensation electric capacity C2 externally connected via compensating end COMP, thus produce and the control signal with dutycycle, and this dutycycle is corresponding with desired output voltage/or electric current.PFC and constant-current control module 221 are connected to drive module 222, and the latter produces the driving signal of switching tube M1 according to control signal.
Preferably, PFC control circuit 220 can also include under-voltage latch (UVLO) and base modules 226.UVLO and base modules 226 obtain supply voltage via input VCC, and produce PFC control circuit 220 and work required supply voltage and reference voltage.
At the secondary of transformator T1, sustained diode 6 and output capacitance Cout are connected to the two ends of the vice-side winding NS of transformator T1.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 one end of output capacitance Cout.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, 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, PFC control circuit 220 controls switching tube M1 alternate conduction and disconnection.
During the conducting of switching tube M1, PFC and constant-current control module 221 produce and drive signal is high level.The drain electrode of switching tube M1 is low level.Electric current flows through switching tube M1, current sampling resistor Rs and primary side winding NP of transformator T1 successively.Thus, transformator T1 stores energy.The primary current of transformator T1 is begun to ramp up by zero, and current sampling signal rises.Meanwhile, the floating ground end GND of PFC control circuit 220 is just, close to DC input voitage Vin.To hold GND be negative to voltage feedback signal relative to floating.
PFC and constant-current control module 121 receive current sampling signal and voltage feedback signal, obtain the ON time of fly-wheel diode according to voltage feedback signal.Then, flowed through electric current and the ON time of fly-wheel diode of switching tube M1 by detection, calculate output electric 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 produce and 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, the discharge current that the vice-side winding NS of transformator T1 provides flows through sustained diode 6, output capacitance Cout and load LED successively.That is, transformator T1 is discharged, by energy conduction to outfan by sustained diode 6.The secondary voltage of transformator T1 is gradually reduced.Meanwhile, primary side winding NP of transformator T1 produces the induced voltage of vice-side winding NS so that the floating ground end GND of PFC control circuit 220 is negative, close to direct-current ground potential.To hold GND be just can be by the ON time of voltage feedback signal detection fly-wheel diode to voltage feedback signal relative to floating.Whole system, by detection current sampling signal and voltage feedback signal, is controlled by loop, reaches constant output current, and have higher power factor value.
Start and power supply circuits 240 are for powering to PFC control circuit 220.During system worked well, when switching tube M1 turns on, the floating ground end GND of PFC control circuit 220 is just.Now, starting and the diode D5 of power supply circuits 240 is not turned on, the energy that system is stored by electric capacity C1 is powered to PFC control circuit 220.During system worked well, when switching tube M1 ends, the floating ground end GND of the different name end of primary side winding NP of transformator T1, i.e. PFC control circuit 220 is negative.Owing to the ground on the former limit of transformator T1 is no-voltage, therefore, the voltage Vnp=N*Vns at the primary side winding NP two ends of transformator T1, wherein, N is the turn ratio of transformator T1, and Vns is the output voltage at the vice-side winding NS two ends of transformator T1.Voltage Vnp is electric capacity C1 charging via resistance R4 and diode D5.Meanwhile, the inside of PFC control circuit 220 uses diode D8 to provide a clamp voltage, for limiting the ceiling voltage of supply voltage.
Therefore, during system worked well, start and electric capacity C1 is periodically charged and discharged by power supply circuits 240, thus 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 the second embodiment.This Switching Power Supply 300 includes transformator T1, and be positioned at the rectifier bridge 110 on the former limit of transformator T1, power factor correcting (PFC) control circuit 320, voltage feedback circuit 330, power supply circuits 340, input capacitance Cin, compensate electric capacity C2, switching tube M1, current sampling resistor Rs, and it is positioned at sustained diode 6 and output capacitance Cout of the secondary of transformator T1.
As it is shown on figure 3, compared to Figure 1, the Switching Power Supply 300 of this embodiment eliminates the auxiliary winding NA of transformator T1.Compared with Fig. 2, the Switching Power Supply 300 of this embodiment use further power supply circuits 340 instead of startup and power supply circuits 240, wherein save for Switching Power Supply startup stage be electric capacity C1 charging resistance R1.
For simplicity's sake, hereafter the circuit module that the second embodiment is identical with first embodiment is no longer described in detail, and only describe the difference of the two.
Power supply circuits 340 include resistance R4, electric capacity C1 and diode D5.The anode of diode D5 is connected to the ground via resistance R4, and negative electrode is connected to the input VCC of PFC control circuit 320, thus is that PFC control circuit provides supply voltage VCC in the normal work stage of Switching Power Supply.
PFC control circuit 320 includes diode D8, PFC and constant-current control module 321, drives module 322, high voltage startup module 325.Diode D8 is connected to input VCC and floating holds between GND, for by supply voltage clamper to fixed voltage, it is to avoid overtension causes circuit to damage.PFC and constant-current control module 321 receive current sampling signal, voltage feedback signal, the compensation electric capacity C2 externally connected via compensating end COMP, thus produce and the control signal with dutycycle, and this dutycycle is corresponding with desired output voltage/or electric current.PFC and constant-current control module 321 are connected to drive module 322, and the latter produces the driving signal of switching tube M1 according to control signal.
Preferably, PFC control circuit 320 can also include UVLO and base modules 326.UVLO and base modules 326 obtain supply voltage via input VCC, and produce PFC control circuit 220 and work required supply voltage and reference voltage.
At the secondary of transformator T1, sustained diode 6 and output capacitance Cout are connected to the two ends of the vice-side winding NS of transformator T1.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 one end of output capacitance Cout.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, 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, PFC control circuit 320 controls switching tube M1 alternate conduction and disconnection.
During the startup of Switching Power Supply 300, the high voltage startup module 325 in PFC control circuit 320 starts for system electrification.
During the normal work of Switching Power Supply 300, power supply circuits 340 are for providing power supply to PFC control circuit 320.When switching tube M1 turns on, the floating ground end GND of PFC control circuit 320 is just.Now, the diode D5 of power supply circuits 340 is not turned on, and the energy that system is stored by electric capacity C1 is powered to PFC control circuit 320.When switching tube M1 ends, the floating ground end GND of the different name end of primary side winding NP of transformator T1, i.e. PFC control circuit 320 is negative.Owing to the ground on the former limit of transformator T1 is no-voltage, therefore, the voltage Vnp=N*Vns at the primary side winding NP two ends of transformator T1, wherein, N is the turn ratio of transformator T1, and Vns is the output voltage at the vice-side winding NS two ends of transformator T1.Voltage Vnp is electric capacity C1 charging via resistance R4 and diode D5.Meanwhile, the inside of PFC control circuit 320 uses diode D8 to provide a clamp voltage, for limiting the ceiling voltage of supply voltage.
Therefore, during system worked well, electric capacity C1 is periodically charged and discharged by power supply circuits 340, thus realizes the power supply to PFC control circuit 320.
Should be noted that, in this article, the relational terms of such as first and second or the like is used merely to separate an entity or operation with another entity or operating space, and not necessarily requires or imply the relation or sequentially that there is any this reality between these entities or operation.And, term " includes ", " comprising " or its any other variant are intended to comprising of nonexcludability, so that include that the process of a series of key element, method, article or equipment not only include those key elements, but also include other key elements being not expressly set out, or also include the key element intrinsic for this process, method, article or equipment.In the case of there is no more restriction, statement " including ... " key element limited, it is not excluded that there is also other identical element in including the process of described key element, method, article or equipment.
According to embodiment of the present utility model as described above, these embodiments do not have all of details of detailed descriptionthe, are not intended to the specific embodiment that this utility model is only described yet.Obviously, as described above, can make many modifications and variations, include but not limited to the amendment to COMP end compensating network building form, the change to the local structure of circuit, the type to components and parts or the replacement of model.These embodiments are chosen and specifically described to this specification, is to preferably explain principle of the present utility model and actual application, so that skilled artisan can utilize this utility model and the amendment on the basis of this utility model to use well.This utility model is only limited by claims and four corner thereof and equivalent.
Claims (13)
1. a Switching Power Supply for primary-side-control, its feature in, including:
Transformator, including primary side winding and vice-side winding；
Switching tube, described switching tube and described primary side winding are connected in series between DC voltage input end and ground, form the current path of described switching tube extremely described primary side winding during the conducting of described switching tube；
Current sampling resistor, is connected between described switching tube and described primary side winding, for obtaining the current sampling signal characterizing the electric current flowing through described switching tube；
Voltage feedback circuit, is connected to the two ends of described primary side winding, for obtaining the voltage feedback signal of the original edge voltage characterizing described primary side winding；
Control circuit, produces the driving signal of described switching tube according to described current sampling signal and described voltage feedback signal, to control conducting and the disconnection of described switching tube,
Wherein, described control circuit has feeder ear and holds floatingly, is respectively used to receive supply voltage and floating earth signal,
Described control circuit obtains described current sampling signal from the primary nodal point between described switching tube and described current sampling resistor, obtains described floating earth signal from the secondary nodal point between described current sampling resistor and described primary side winding.
Switching Power Supply the most according to claim 1, its feature in, during the disconnection of described switching tube, the original edge voltage of described primary side winding is the induced voltage of the secondary voltage of described vice-side winding.
Switching Power Supply the most according to claim 1, its feature in, also include:
Rectifier bridge, for being transformed into DC pulse moving voltage by the alternating voltage that outside alternating current power supply provides；And
Input capacitance, for filtering DC pulse moving voltage to produce DC input voitage, the first end of described input capacitance is as described DC voltage input end, the second end ground connection.
Switching Power Supply the most according to claim 1, its feature in, also include:
Fly-wheel diode, the anode of described fly-wheel diode is connected to the first end of described vice-side winding；And
Output capacitance, described output capacitance is connected between the negative electrode of described fly-wheel diode and the second end of described vice-side winding,
Wherein, the two ends of described output capacitance provide the output voltage of described Switching Power Supply.
Switching Power Supply the most according to claim 2, its feature in, also include: power supply circuits, described power supply circuits include being connected in series in and described hold floatingly between the first resistance, the first diode and the first electric capacity,
Wherein, the anode of described first diode is connected to described first resistance, and negative electrode is connected to described first electric capacity, and the 3rd node between described first diode and described first electric capacity is connected to described feeder ear.
Switching Power Supply the most according to claim 5, its feature in, during the conducting of described switching tube, described floating ground end is just, described first diode does not turns on, and described first electric capacity is in discharge condition,
During the disconnection of described switching tube, described floating ground end is negative, described first diode current flow, utilizes induced voltage to charge described first electric capacity,
Described power supply circuits utilize the alternately charging and discharging of described first electric capacity to be that described control circuit is powered.
Switching Power Supply the most according to claim 5, its feature in, also include the second resistance, described second resistance is connected between described DC voltage input end and described 3rd node, thus described Switching Power Supply startup stage utilize DC input voitage to described first electric capacity charging, to provide the supply voltage of described control circuit.
Switching Power Supply the most according to claim 2, its feature includes the potential-divider network of the multiple resistance composition being connected in series in, described voltage feedback circuit, and described voltage feedback signal is the voltage division signal of described floating earth signal.
Switching Power Supply the most according to claim 2, its feature in, described control circuit includes:
Constant-current control module, described constant-current control module receives described current sampling signal, described voltage feedback signal, and produces and the control signal with dutycycle；And
Drive module, receive described control signal from described constant-current control module, and produce the driving signal of described switching tube.
Switching Power Supply the most according to claim 9, wherein, described constant-current control module is via the compensating module outside the compensation end connection of described control circuit, to maintain system stability.
11. Switching Power Supplies according to claim 10, its feature in, described compensating module include being connected to described compensation end and described hold floatingly between electric capacity or compensation of resistance and capacitance network.
12. Switching Power Supplies according to claim 9, its feature in, described control circuit also includes:
High voltage startup module, for described Switching Power Supply startup stage be that described control circuit is powered.
13. Switching Power Supplies according to claim 1, its feature in, first end of described primary side winding is connected to described end and the second end ground connection floatingly, first end and second end of described vice-side winding are respectively hot end and cold end, further, the second end of described primary side winding and the first end of described vice-side winding are Same Name of Ends.
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| CN201620167695.7U CN205509876U (en) | 2016-03-04 | 2016-03-04 | Primary side -controlled switching power supply |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201620167695.7U CN205509876U (en) | 2016-03-04 | 2016-03-04 | Primary side -controlled switching power supply |
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| CN205509876U true CN205509876U (en) | 2016-08-24 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109245538A (en) * | 2018-09-21 | 2019-01-18 | 陕西亚成微电子股份有限公司 | A kind of Vcc power supply circuit of inverse-excitation type switch power-supply control circuit |
| CN113992027A (en) * | 2021-10-26 | 2022-01-28 | 珠海格力电器股份有限公司 | Isolating switch power supply control circuit, method and device and isolating switch power supply |
| CN114624499A (en) * | 2022-03-15 | 2022-06-14 | 无锡市晶源微电子有限公司 | Output voltage sampling circuit of switching power supply |
| CN116760286A (en) * | 2023-08-21 | 2023-09-15 | 深圳市力生美半导体股份有限公司 | Switching power supply driving circuit and switching power supply |
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2016
- 2016-03-04 CN CN201620167695.7U patent/CN205509876U/en active Active
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109245538A (en) * | 2018-09-21 | 2019-01-18 | 陕西亚成微电子股份有限公司 | A kind of Vcc power supply circuit of inverse-excitation type switch power-supply control circuit |
| CN113992027A (en) * | 2021-10-26 | 2022-01-28 | 珠海格力电器股份有限公司 | Isolating switch power supply control circuit, method and device and isolating switch power supply |
| CN113992027B (en) * | 2021-10-26 | 2023-09-08 | 珠海格力电器股份有限公司 | Isolation switch power supply control circuit, method and device and isolation switch power supply |
| CN114624499A (en) * | 2022-03-15 | 2022-06-14 | 无锡市晶源微电子有限公司 | Output voltage sampling circuit of switching power supply |
| CN114624499B (en) * | 2022-03-15 | 2023-09-19 | 无锡市晶源微电子股份有限公司 | Output voltage sampling circuit of switching power supply |
| CN116760286A (en) * | 2023-08-21 | 2023-09-15 | 深圳市力生美半导体股份有限公司 | Switching power supply driving circuit and switching power supply |
| CN116760286B (en) * | 2023-08-21 | 2024-02-02 | 深圳市力生美半导体股份有限公司 | Switching power supply driving circuit and switching power supply |
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