CN116961432B - A switching power supply fast charging system and a secondary side control method without optocoupler - Google Patents
A switching power supply fast charging system and a secondary side control method without optocoupler Download PDFInfo
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- CN116961432B CN116961432B CN202310790496.6A CN202310790496A CN116961432B CN 116961432 B CN116961432 B CN 116961432B CN 202310790496 A CN202310790496 A CN 202310790496A CN 116961432 B CN116961432 B CN 116961432B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
本发明公开一种开关电源快充系统及其无光耦次级侧控制方法，涉及开关电源领域。本发明开关电源快充系统的初级侧控制器包括初级侧驱动控制单元、初级侧开通信号接收单元和电流峰值控制单元；次级侧控制器包括同步整流驱动控制单元、初级侧开通信号发送单元、协议检测单元、恒压控制单元、恒流控制单元和次级侧驱动控制单元。本发明在次级侧检测并控制输出电压电流，次级侧将开通信息通过变压器耦合传递至初级侧，实现在无光耦和无特殊封装的情况下由次级侧控制输出电压和电流，达到高精度低成本的目标。同时，本发明开关电源快充系统很容易实现初级侧功率管零电压开通，降低了开通损耗，提高了系统效率。
The present invention discloses a switching power supply fast charging system and a secondary side control method without optocoupler, and relates to the field of switching power supplies. The primary side controller of the switching power supply fast charging system of the present invention includes a primary side drive control unit, a primary side turn-on signal receiving unit and a current peak control unit; the secondary side controller includes a synchronous rectification drive control unit, a primary side turn-on signal sending unit, a protocol detection unit, a constant voltage control unit, a constant current control unit and a secondary side drive control unit. The present invention detects and controls the output voltage and current on the secondary side, and the secondary side transmits the turn-on information to the primary side through transformer coupling, so that the output voltage and current are controlled by the secondary side without optocoupler and special packaging, achieving the goal of high precision and low cost. At the same time, the switching power supply fast charging system of the present invention can easily realize zero voltage turn-on of the primary side power tube, reduce turn-on loss, and improve system efficiency.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to a switching power supply quick charging system and a non-coupler secondary side control method thereof.
Background
The switching power supply has the advantages of small size, high conversion efficiency and the like, and the application field of the switching power supply is continuously expanded, and the switching power supply comprises a charger, an adapter and the like. The primary side (or primary side) controlled switching power supply is widely adopted because an optocoupler is not needed, the control is simple, and the cost is low.
In recent years, the main countries in the world have raised requirements on the conversion efficiency of the switching power supply, and in order to meet the latest grade requirements (second stage) of energy efficiency of the European Union and the grade VI energy efficiency requirements of the U.S. department, the switching power supply generally adopts a synchronous rectification technology to raise the efficiency. Along with the rapid development of the rapid charging of the mobile phone, the precision requirements of the output voltage and the output current of the charger are higher and higher, and meanwhile, the output power of the charger is required to be no longer fixed, and the output voltage and the output current are required to be adjusted according to the load requirement of the mobile phone. The charger meeting the USB PD 3.0 specification has an output voltage variation range of 3V-21V and a minimum voltage interval of 20mV. These requirements present a number of challenges for primary side controlled switching power supply applications.
The conventional primary-side controlled switching power supply charger circuit includes an ac input port (an ac voltage range is typically 85VAC to 265 VAC), a rectifier bridge (converting the ac voltage VAC into a dc voltage VIN), an input capacitor, a transformer, a primary-side controller, a primary-side power switching tube, a secondary-side (or secondary-side) synchronous rectifying power switching tube, an output capacitor, a secondary-side controller, an output port, and the like, wherein the output voltage and current are controlled by the primary-side controller, the secondary-side output voltage auxiliary winding voltage is coupled through detection and sampling, the sampled value is compared with a level in the controller, and an on signal is generated after error amplification, so as to control the output voltage to be constant. While the secondary side controller is used only for synchronous rectification control. The output voltage of the scheme is controlled by the primary side controller, an optocoupler is not needed, the control is simple, the cost is low, and the scheme is widely used in the application of a switching power supply with single output voltage and current requirements.
However, if the charging is fast, the load end has a requirement of switching output voltage and current, and the primary side controller cannot obtain the conversion information in real time, so that the requirement is difficult to meet. The existing primary side controlled switching power supply fast charging system circuit detects the voltage and current requirements of a load end through a secondary protocol detection unit, then a voltage and current information sending unit codes voltage and current requirement information and then controls a switching tube to be turned on and off through a secondary drive control unit, the voltage and current requirement information is transmitted to a primary side through a transformer, and after the voltage and current information receiving unit of the primary side detects the voltage and current information, the voltage and current information is transmitted to a constant voltage and constant current module to be adjusted, and then the switching tube of the primary side is controlled to be turned on, so that the change of the load end is met. However, the accuracy of the output voltage of the primary side control method is limited by the error of the primary side sampling output voltage, and generally, the method can only meet +/-5% mass production accuracy, and is difficult to achieve higher voltage accuracy.
In addition, the existing switching power supply fast charging system circuit without the coupler secondary side control puts the primary side controller and the secondary side controller into the same package. The output voltage is directly detected and regulated by the secondary side controller, so that higher voltage precision can be ensured, the mass production level of +/-2.5% is achieved, but special packaging is needed, and the system cost is high.
Disclosure of Invention
Aiming at the problems in the background technology, the invention provides a switching power supply quick charging system and a non-coupler secondary side control method thereof, so as to improve the output voltage precision and reduce the system cost under the condition of no need of optocouplers and special packaging.
In order to achieve the above object, the present invention provides the following solutions:
a switching power supply fast charge system comprising:
An input port coupled to an ac input voltage VAC;
a first rectifier coupled to the input port for converting the ac voltage to a dc voltage;
An input capacitor coupled to the first rectifier for filtering the dc voltage output by the first rectifier;
An output capacitor coupled to the output port;
an output port for providing voltage and current to a load, comprising protocol terminals;
The transformer comprises a first winding, a second winding and a third winding, wherein the first winding is coupled to an input capacitor and a primary side power switch tube;
A primary side power switching tube coupled to the primary side controller, the transformer first winding and the primary side current sense resistor;
a secondary side power switch tube coupled to the secondary side controller and the transformer second winding;
a primary side controller including a primary side drive control unit, a primary side on signal receiving unit, and a current peak control unit;
the primary side drive control unit is used for controlling the ON and off of the primary side power switch tube, the ON signal PRI_ON_EN of the primary side power switch tube is obtained from the primary side ON signal receiving unit, and the off signal is generated by the current peak value control unit;
The primary side turn-ON signal receiving unit is used for detecting turn-ON information sent by the secondary side by detecting the common terminal voltage of the voltage dividing resistor, and generating a turn-ON signal PRI_ON_EN of the primary side power switching tube so as to control the turn-ON of the primary side power switching tube;
The current peak value control unit is used for detecting the current flowing through the primary side current detection resistor and comparing the current peak value with a current peak value level so as to control the peak value of the primary side current;
the secondary side controller comprises a synchronous rectification driving control unit, a primary side opening signal transmitting unit, a protocol detecting unit, a constant voltage control unit, a constant current control unit and a secondary side driving control unit;
The synchronous rectification drive control unit is used for controlling the secondary side power switch tube to be turned ON when the transformer demagnetizes and rectifies by detecting the drain voltage of the secondary side power switch tube and generating a drive signal SR_ON;
The primary side turn-ON signal sending unit is used for generating a primary side turn-ON signal PRI_ON according to a constant voltage control signal CV_EN and a constant current control signal CC_EN output by the constant voltage control unit and the constant current control unit, transmitting the primary side turn-ON signal PRI_ON to the secondary side driving control unit so as to control the turn-ON of the secondary side power switching tube except for the extra preset time during rectification, and then transmitting turn-ON information to the primary side through transformer coupling;
the protocol detection unit is used for communicating with the load end through a protocol terminal of the detection output port, obtaining voltage and current information output by the load end through a detection protocol, generating a constant voltage level CV_REF and transmitting the constant voltage level CV_REF to the constant voltage control unit, and generating a constant current level CC_REF and transmitting the constant current level CC_REF to the constant current control unit;
The constant voltage control unit is used for directly sampling the secondary side output voltage and comparing the secondary side output voltage with a constant voltage level CV_REF to generate a constant voltage control signal CV_EN;
The constant current control unit is used for directly sampling the secondary side output current or indirectly calculating the secondary side output current to generate a constant current control signal CC_EN;
the secondary side driving control unit is used for controlling the ON and off of the secondary side power switch tube according to the driving signal SR_ON of the synchronous rectification driving control unit and the primary side ON signal PRI_ON of the primary side ON signal transmitting unit.
Optionally, the constant current control unit directly detects the voltage of the output current detection resistor and compares the detected voltage with a constant current level cc_ref to generate a constant current control signal cc_en.
Optionally, the constant current control unit uses a formula of io= (1/2) IPK NPS TONS/TSW to control the output current IO by controlling the switching period TSW to generate the constant current control signal cc_en, where IPK is a peak value of the primary side current, NPS is a turn ratio of the first winding and the second winding of the transformer, and TONS is a rectifying time of the secondary side power switch tube.
The primary side opening signal transmitting unit comprises an AND gate, a pulse width control unit and a trigger, wherein a first input port and a second input port of the AND gate are respectively coupled to an output end of the constant voltage control unit and an output end of the constant current control unit, an output end of the AND gate is coupled to an input end of the pulse width control unit and a second input port of the trigger, an output end of the pulse width control unit is coupled to a first input port of the trigger, and an output end of the trigger serving as an output end of the primary side opening signal transmitting unit is coupled to the secondary side driving control unit.
Optionally, the pulse width control unit comprises a current source, a second switch, a second capacitor and a second comparator, wherein an output end of the current source is coupled to a first port of the second switch, a second port of the second switch and a first port of the second capacitor are coupled to a first input port of the second comparator, a control end of the second switch is coupled to an output end of an AND gate in the primary side on signal transmitting unit, a second port of the second capacitor is coupled to ground, a second input port of the second comparator is coupled to a third level, and an output end of the second comparator is coupled to a first input port of a trigger of the primary side on signal transmitting unit as an output end of the pulse width control unit.
Optionally, the primary side turn-on signal receiving unit includes a first voltage-controlled current source, a second voltage-controlled current source, a DEMAG unit, a first switch, a first comparator and a first capacitor, a common terminal of a voltage dividing resistor is coupled to an input terminal of the DEMAG unit, a control terminal of the first voltage-controlled current source and a control terminal of the second voltage-controlled current source, an output terminal of the first voltage-controlled current source, an output terminal of the second voltage-controlled current source, a second port of the first switch and a first input port of the first comparator are all coupled to a first port of the first capacitor, the first port of the first switch is coupled to a first level Vref1, a control port of the first switch is coupled to an output terminal of the DEMAG unit, a second input port of the first comparator is coupled to a second level Vref2, and an output terminal of the first comparator is coupled to the primary side driving control unit as an output terminal of the primary side turn-on signal receiving unit.
The control method of the secondary side without coupler is applied to the switching power supply quick charging system, the control method of the secondary side without coupler detects and controls output voltage and current at the secondary side, and the secondary side transmits opening information to the primary side through transformer coupling, and the control method comprises the following steps:
The protocol detection unit detects a protocol terminal in an output port to obtain voltage and current information, generates a constant voltage level CV_REF and a constant current level CC_REF according to the voltage and current information, and transmits the constant voltage level CV_REF and the constant current level CC_REF to the constant voltage control unit and the constant current control unit respectively;
the constant voltage control unit directly samples the secondary side output voltage and compares the secondary side output voltage with a constant voltage level CV_REF to generate a constant voltage control signal CV_EN;
The constant current control unit directly samples the secondary side output current or indirectly calculates the secondary side output current, and generates a constant current control signal CC_EN based on a constant current level CC_REF;
The primary side switching-ON signal transmitting unit generates a switching-ON signal PRI_ON according to a constant voltage control signal CV_EN and a constant current control signal CC_EN and transmits the switching-ON signal PRI_ON to the secondary side driving control unit, the secondary side driving control unit controls the additional switching-ON of the secondary side power switching tube for a preset time, and switching-ON information is transmitted to the primary side controller through transformer coupling;
The primary side turn-ON signal receiving unit detects the common terminal voltage of the voltage dividing resistor coupled to the third winding of the transformer, and generates a turn-ON signal PRI_ON_EN of the primary side power switching tube after detecting the turn-ON information sent by the secondary side so as to control the turn-ON of the primary side power switching tube and realize the secondary side control of the optoless coupler.
Optionally, when the constant voltage control signal cv_en and the constant current control signal cc_en are both 1, the and gate output EN of the primary side turn-ON signal transmitting unit is 1, the trigger is set to 1, and the pulse width control unit starts timing, and the trigger is set to 0 once the timing is completed, the output pri_on of the trigger is the pulse width, the turn-ON signal pri_on is transmitted to the secondary side driving control unit, and the secondary side power tube is controlled to be additionally turned ON by the pulse width, and the additional conduction is coupled to the third winding of the transformer through the transformer, so that the transmission process of the turn-ON information is completed.
Optionally, when the and gate output EN is 1, the second switch is closed, the current source starts to charge the second capacitor, and when the voltage of the second capacitor is charged above the third level Vref3, the second comparator output Tstop is 1, the trigger of the primary side ON signal transmitting unit is set to 0, and the ON signal pri_on is ended.
Optionally, before the secondary side sends the turn-ON information, the voltage pri_on_det of the first capacitor in the primary side turn-ON signal receiving unit is always lower than the second level Vref2, the pri_on_en is always maintained to be 0, after the secondary side sends the turn-ON information, the pri_on_det is charged to be above the second level Vref2, the turn-ON signal pri_on_en output by the first comparator is changed to 1, the turn-ON signal pri_on_en is transmitted to the primary side driving control unit, and the primary side power switching tube is turned ON immediately after the secondary turn-ON information is sent.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
The invention provides a switching power supply quick charge system and a non-coupling secondary side control method thereof, wherein a primary side controller comprises a primary side driving control unit, a primary side opening signal receiving unit and a current peak control unit; the secondary side controller comprises a synchronous rectification driving control unit, a primary side opening signal transmitting unit, a protocol detecting unit, a constant voltage control unit, a constant current control unit and a secondary side driving control unit. The invention detects and controls the output voltage and current at the secondary side, the secondary side transmits the opening information to the primary side through transformer coupling, and the output voltage and current are controlled by the secondary side under the conditions of no optocoupler and no special package, thereby achieving the aim of high precision and low cost. Meanwhile, the switching power supply quick-charging system can easily realize zero-voltage switching-on of the primary side power tube, reduces switching-on loss and improves system efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a switching power supply fast charging system according to the present invention;
FIG. 2 is a main waveform diagram of the switching power supply quick charge system of the present invention;
FIG. 3 is a schematic circuit diagram of a primary-side turn-on signal transmitting unit according to the present invention;
FIG. 4 is a schematic circuit diagram of a primary-side turn-on signal receiving unit according to the present invention;
FIG. 5 is a main operation waveform diagram of the primary-side turn-on signal receiving unit of the present invention;
FIG. 6 is a schematic circuit diagram of a pulse width control unit according to the present invention;
fig. 7 is a waveform diagram of the zero voltage turn-on of the primary side power switch.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a switching power supply quick-charging system and a non-coupler secondary side control method thereof, so that the output voltage precision is improved and the system cost is reduced under the condition that an optocoupler and special packaging are not needed.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Fig. 1 is a schematic circuit diagram of a switching power supply fast charging system according to the present invention. Referring to fig. 1, the switching power supply fast charge system includes an input port IN, a first rectifier 40, a primary side controller 41, a secondary side controller 42, an input capacitor 43, a primary side power switching transistor 44, a primary side current detection resistor 45, a voltage dividing resistor 46, a transformer 47, a secondary side power switching transistor 48, an output terminal capacitor 49, and an output port OUT.
Wherein the input port IN is coupled to the ac input voltage VAC. The first rectifier 40 is coupled to the input port IN and converts the ac voltage VAC into the dc voltage VIN. An input capacitor 43 is coupled to the first rectifier 40 for filtering the dc voltage VIN output by the first rectifier 40. An output capacitor 49 is coupled to the output port OUT. The output port OUT provides voltage and current to the load, including protocol terminals. The transformer 47 comprises a first winding NP coupled to the input capacitor 43 and the primary side power switching tube 44, a second winding NS coupled to the output capacitor 49 and the secondary side power switching tube 48, and a third winding NA coupled to the voltage dividing resistor 46. A primary side power switch tube 44 is coupled to the primary side controller 41, the transformer first winding NP and the primary side current detection resistor 45. A secondary side power switching tube 48 is coupled to the secondary side controller 42 and the transformer second winding NS.
Specifically, as shown in fig. 1, one end of the input capacitor 43 is connected to the first rectifier 40, and the other end of the input capacitor 43 is grounded. One end of the transformer first winding NP is connected to one end of the input capacitor 43, and the other end of the transformer first winding NP is connected to the drain of the primary side power switching transistor 44. One end of the second winding NS of the transformer is connected with one end of the output end capacitor 49, the other end of the second winding NS of the transformer is connected with the drain electrode of the secondary side power switching tube 48, and the other end of the output end capacitor 49 is connected with the source electrode of the secondary side power switching tube 48. One end of the third winding NA of the transformer is connected with one end of the voltage dividing resistor 46, the other end of the third winding NA of the transformer is grounded, and the other end of the voltage dividing resistor 46 is grounded.
Referring to fig. 1, the primary side controller 41 includes a primary side drive control unit 411, a primary side on signal receiving unit 412, and a current peak control unit 413.
Wherein the primary side driving control unit 411 is connected to the gate of the primary side power switch tube 44 for controlling the ON and off of the primary side power switch tube 44, the ON signal pri_on_en of the primary side power switch tube 44 is obtained from the primary side ON signal receiving unit 412, and the off signal SD is generated by the current peak control unit 413.
The primary side turn-ON signal receiving unit 412 is connected to a common terminal of the voltage dividing resistor 46, and is configured to detect the turn-ON information sent from the secondary side by detecting the common terminal voltage VS of the voltage dividing resistor 46, and generate the turn-ON signal pri_on_en of the primary side power switch 44 to control the turn-ON of the primary side power switch 44.
The current peak control unit 413 is connected to one end of the primary side current detection resistor 45 and the source of the primary side power switching transistor 44, and the other end of the primary side current detection resistor 45 is grounded. The current peak control unit 413 is configured to detect a current flowing through the primary side current detection resistor 45 and compare the detected current with a current peak level to control a peak value of the primary side current IP.
The secondary side controller 42 includes a synchronous rectification drive control unit 421, a primary side on signal transmission unit 422, a protocol detection unit 423, a constant voltage control unit 424, a constant current control unit 425, and a secondary side drive control unit 426.
The synchronous rectification driving control unit 421 is connected to the drain of the secondary side power switch tube 48, and is configured to control the secondary side power switch tube 48 to be turned ON during the demagnetizing rectification of the transformer 47 by detecting the drain voltage DET of the secondary side power switch tube 48 and generating a driving signal sr_on.
The primary side turn-ON signal transmitting unit 422 is configured to generate a primary side turn-ON signal pri_on according to the constant voltage control signal cv_en and the constant current control signal cc_en output from the constant voltage control unit 424 and the constant current control unit 425, transmit the primary side turn-ON signal pri_on to the secondary side driving control unit 426, control the secondary side power switching tube 48 to turn ON for a short period of preset time except for rectification, and then couple the primary side power switching tube with the transformer 47 to transmit turn-ON information to the primary side.
The protocol detection unit 423 is connected to the protocol terminal of the output port OUT, and is configured to communicate with the load terminal through detecting the protocol terminal of the output port OUT, obtain the output voltage and current information of the load terminal through detecting the protocol, generate a constant voltage level cv_ref, transmit the constant voltage level cv_ref to the constant voltage control unit 424, generate a constant current level cc_ref, and transmit the constant current level cc_ref to the constant current control unit 425.
The constant voltage control unit 424 is configured to directly sample the secondary side output voltage VO and compare with a constant voltage level cv_ref to generate a constant voltage control signal cv_en.
The constant current control unit 425 is configured to directly sample the secondary side output current IO or indirectly calculate the secondary side output current IO to generate the constant current control signal cc_en, which kind of constant current control method is not limited by the present invention.
The method of directly sampling the secondary side output current IO refers to that the constant current control unit 425 directly detects the current IO of the output current detection resistor and compares the current IO with the constant current level cc_ref to generate the constant current control signal cc_en.
The method for indirectly calculating the secondary side output current IO refers to that the constant current control unit 425 uses a formula of io= (1/2) IPK NPS TONS/TSW to control the output current IO by controlling a switching period TSW to generate a constant current control signal cc_en, where IPK is a peak value of the primary side current and is a fixed value, NPS is a turn ratio of the first winding NP and the second winding NS of the transformer, and TONS is a rectifying time of the secondary side power switch tube. In the intermittent and critical operation modes, IPK is fixed and TONS is also fixed, so that the output current IO can be controlled by controlling the switching period TSW only, and the constant current control signal cc_en is generated.
The secondary side driving control unit 426 is connected to the gate of the secondary side power switch 48, and is configured to control the ON/off of the secondary side power switch 48 according to the driving signal sr_on of the synchronous rectification driving control unit 421 and the primary side ON signal pri_on of the primary side ON signal transmitting unit 422.
The protocol detection unit 423 detects a protocol terminal in an output port OUT to obtain voltage and current information, and generates a constant voltage level CV_REF and a constant current level CC_REF, which are respectively transmitted to the constant voltage control unit 424 and the constant current control unit 425, the constant voltage control unit 424 and the constant current control unit 425 detect and control the output voltage VO and the current IO ON the secondary side and generate control signals CV_EN and CC_EN, the primary side opening signal transmitting unit 422 generates a primary side opening signal PRI_ON, the primary side opening signal PRI_ON is additionally opened for a short period of time through the secondary driving control unit 426, the secondary side power switch tube 48 is additionally opened through the transformer 47 for coupling, the opening information is transmitted to the primary side controller 41, the primary side opening signal receiving unit 412 detects the common terminal voltage VS of the voltage dividing resistor 46 coupled to the third winding NA of the transformer, and the opening signal PRI_ON_EN of the primary side power switch tube 44 is generated after the opening information sent by the secondary side is detected, so as to control the opening signal PRI_ON_ON of the primary side power switch tube 44. In this process, the system output voltage VO and current IO are detected and controlled by the secondary side controller 42, and generate turn-on information, which is transmitted to the primary side through the transformer 47 to control the turn-on of the primary side power switching transistor 44, so as to implement the secondary side control without optocouplers.
Fig. 2 is a main waveform diagram of the switching power supply fast charging system of the present invention. In the figure, cc_en is a constant current control signal output from the constant current control unit 425, and cc_en=1 indicates that the constant current control condition is satisfied. Cv_en is a constant voltage control signal output from the constant voltage control unit 424, and cv_en=1 indicates that the constant voltage control condition is satisfied. Pri_on is the primary side ON signal output from the primary side ON signal transmission unit 422, and pri_on=1 when both constant voltage and constant current conditions are satisfied, i.e., cv_en and cc_en are both 1.VOUT is a driving voltage of the primary side power switching transistor 44, and is output from the primary side controller 41. The DRI is the driving voltage of the secondary side power switching tube 48, and is sent by the secondary side controller 42 according to the secondary side rectified driving signal sr_on and the primary side ON signal pri_on. VS is the common terminal voltage of the divider resistor 46 coupled to the third winding NA of the transformer.
As shown in fig. 2, at the constant voltage output, cc_en=1 of the constant current control unit 425 generates primary side ON information when cv_en=1 of the constant voltage control unit 424, the primary side ON signal transmitting unit 422 transmits a narrow pulse signal pri_on to the secondary side driving control unit 426, and the secondary side driving control unit 426 outputs DRI to control the secondary side power switching transistor 48 to be additionally turned ON for a short period of time. The transformer 47 couples the turn-ON information to the third winding NA of the transformer, and the primary turn-ON signal receiving unit 412 in the primary side controller 41 generates pri_on_en to the primary side driving control unit 411 to control the primary side power switch 44 to be turned ON immediately after detecting the turn-ON information by detecting the common terminal voltage VS of the voltage dividing resistor 46. This process is a process in which the secondary side passes on information to the primary side and turns on the primary side power switching transistor 44.
In the switching power supply quick-charging system of the present invention shown in fig. 1, the transmission and transfer of the primary-side on signal are key points of the present invention. The primary side drive control unit 411 and the current peak control unit 413 in the primary side controller 41, and the synchronous rectification drive control unit 421, the protocol detection unit 423, the constant voltage control unit 424, the constant current control unit 425, and the secondary side drive control unit 426 in the secondary side controller 42 are not described in detail too much, and only the implementation of the primary side on signal transmission unit 422 in the secondary controller 42 and the primary side on signal reception unit 412 in the primary side controller 41 will be described in detail.
Fig. 3 is a circuit schematic of the primary side on signal transmitting unit of the present invention, and as shown in fig. 3, the primary side on signal transmitting unit 422 includes an and gate 4221, a pulse width control unit 4222 and a trigger 4223. The first and second input ports of the and gate 4221 are coupled to the output terminal of the constant voltage control unit 424 and the output terminal of the constant current control unit 425, i.e., the constant voltage control signal cv_en and the constant current control signal cc_en, respectively. The output of the AND gate 4221 generates an enable signal EN, which is coupled to the input of the pulse width control unit 4222 and to the second input port of the flip-flop 4223, the output of the pulse width control unit 4222 generates a timing end signal Ttop, which is coupled to the first input port of the flip-flop 4223, and the output of the flip-flop 4223 acts as the output of the primary side ON signal transmitting unit 422, which generates a PRI_ON primary side ON signal, which is coupled to the secondary side drive control unit 426.
When the constant voltage, constant current control signals cv_en and cc_en are all 1, the and gate 4221 outputs EN 1, sets the flip-flop 4223 to 1, and the pulse width control unit 4222 starts to count time, sets the flip-flop 4223 to 0 as soon as the time arrives, and outputs pri_on of the flip-flop 4223, i.e., the pulse width. The pulse width by which the secondary side power transistor 48 is additionally turned ON may be controlled by passing pri_on to the secondary side drive control unit 426. This additional conduction is coupled to the third winding NA of the transformer via the transformer 47, which is the transmission of the turn-on signal.
The primary-side turn-on signal receiving unit 412 detects the common terminal voltage of the voltage dividing resistor 46 coupled to the third winding NA of the transformer to determine whether the primary-side power switch 44 needs to be turned on. Fig. 4 is a circuit diagram of the primary-side turn-on signal receiving unit of the present invention. Referring to fig. 4, the primary-side turn-ON signal receiving unit 412 includes a first voltage-controlled current source 4121, a second voltage-controlled current source 4122, a DEMAG unit 4123, a first switch SW1, a first comparator 4124 and a first capacitor C1, a common terminal of a voltage-dividing resistor 46 is coupled to an input terminal of the DEMAG unit 4123, a control terminal of the first voltage-controlled current source 4121 and a control terminal of the second voltage-controlled current source 4122, an output terminal of the first voltage-controlled current source 4121, an output terminal of the second voltage-controlled current source 4122, a second port of the first switch SW1 and a first input port of the first comparator 4124 are all coupled to a first port of the first capacitor C1, a first port of the first switch SW1 is coupled to a first level Vref1, a control port of the first switch SW1 is coupled to an output terminal of the DEMAG unit 4123, a second input port of the first comparator 4124 is coupled to a second level 2, and an output terminal of the first comparator 4124 is used as an output terminal of the primary-side signal receiving unit 412, and a primary-side power switch 44_on signal is generated and a primary-side turn-ON signal is coupled to a primary-side driving unit en_driving unit.
In fig. 4, pri_on_det is the voltage of the first capacitor C1, vs+ is the positive voltage ON the common terminal voltage VS of the voltage dividing resistor 46, and is generally output-coupled to the third winding NA of the transformer in direct proportion to the output voltage VO during secondary rectification, VS-is the negative voltage of VS, and is generally the voltage VIN of the input capacitor 43 is coupled to the third winding NA of the transformer in direct proportion to VIN when the primary power switch 44 is turned ON, and demag_p is a narrow pulse generated by the DEMAG unit 4123 when VS passes down through 0 point.
The on signal detects the volt-second difference in the common terminal voltage VS of the voltage dividing resistor 46 in a period in which neither the primary side nor the secondary side power transistors are operated after the secondary demagnetization is completed. Normally, the voltage seconds of the adjacent positive and negative half cycles on the VS are substantially equivalent, and if the secondary side is additionally turned on for a short period of time, the voltage seconds of the positive half cycle will be greater than the voltage seconds of the first negative half cycle, so as to determine whether the secondary side has additional on to send the primary side on signal. As shown in fig. 4, the narrow pulse demag_p generated when VS crosses 0 point down sets pri_on_det to Vref1, generates a current proportional to VS negative voltage to discharge the first capacitor C1 in the negative half cycle of VS, and generates a current proportional to VS positive voltage to charge the first capacitor C1 in the positive half cycle of VS. In the absence of other disturbances, the volt-seconds of adjacent positive and negative half cycles ON VS are substantially comparable, so the pri_on_det voltage is near Vref1, generally less than Vref2 (Vref 2> Vref 1), and the first comparator 4124 outputs pri_on_en=0. When the secondary side sends the turn-ON signal, the positive half cycle VS is maintained until the turn-ON signal is finished, the C1 charging time is prolonged, pri_on_det is above Vref2, and is greater than Vref2, and the first comparator 4124 outputs pri_on_en=1. This signal is passed to the primary side drive control unit 411, which controls the primary side power switching transistor 44 to be turned on.
Fig. 5 is a main operation waveform diagram of the primary-side turn-on signal receiving unit of the present invention. In the figure, pri_on_det is the voltage of the first capacitor C1, demag_p is a narrow pulse generated when VS passes down through 0 point, and is the output of DEMAG unit 4123, and other signals are the same as those in fig. 4. As shown in fig. 5, the voltage pri_on_det of the first capacitor C1 is always lower than Vref2, and pri_on_en is always maintained at 0 until the secondary side emits the ON signal. When the secondary side sends out the ON signal, pri_on_det is charged above Vref2, and the first comparator 4124 outputs pri_on_en to become 1. This signal is transmitted to the primary side drive control unit 411, and the primary side power switching transistor 44 is turned on immediately after the secondary on signal transmission is completed. The primary side and secondary side opening signals are transmitted, so that secondary side control is realized under the conditions of no optocoupler and no special package, and the aim of high precision and low cost is fulfilled.
Fig. 6 is a circuit schematic diagram of a pulse width control unit according to the present invention, referring to fig. 6, the pulse width control unit 4222 includes a current source I1, a second switch SW2, a second capacitor C2 and a second comparator 42221, wherein an output terminal of the current source I1 is coupled to a first port of the second switch SW2, a second port of the second switch SW2 and a first port of the second capacitor C2 are coupled to a first input port of the second comparator 42221, a control terminal of the second switch SW2 is coupled to an output terminal of the and gate 4221 in the primary side on signal transmitting unit 422, i.e. to an enable signal EN, a second port of the second capacitor C2 is coupled to ground, a second input terminal of the second comparator 42221 is coupled to a third reference Vref3, and an output terminal of the second comparator 42221 is used as an output terminal of the pulse width control unit 4222, and generates a timing end signal Tstop to be coupled to a first input port of the trigger 4223 of the primary side on signal transmitting unit 422.
When the output EN of the and gate 4221, which is input from the constant voltage and constant current control unit, is 1, the second switch SW2 is turned on, the current source I1 starts to charge the second capacitor C2, and when the voltage VC2 of C2 is charged to the third level Vref3 or higher, the second comparator 42221 outputs Tstop as 1, and the trigger 4223 of the primary side on signal transmitting unit 422 is set to 0, ending the on signal.
In addition, the secondary side is additionally turned on for a short period of time in advance, so that the primary side is informed of the turn-on mode, zero-voltage turn-on of the primary side can be achieved, turn-on loss is greatly reduced, and efficiency is improved. Fig. 7 is a waveform diagram of the primary side power switch tube zero voltage on. In the figure, IP IS a current flowing into the primary winding NP of the transformer, IS a current flowing out of the secondary winding NS of the transformer, vdrain IS a drain voltage of the primary power switching transistor 44, and VIN IS a voltage of the input capacitor 43.
As shown in fig. 7, during the period t0-t1, the secondary side sends an on message to the primary side, and the secondary side current IS inversely stores energy in the transformer 47. At time t1, the transmission of the turn-on information IS finished, and the secondary reverse current IS flyback to the primary side, and at the moment, the primary side current IP IS the largest in negative direction. In the period t1-t2, the negative direction IP transfers energy to the primary side input capacitor 43, the primary side power switch 44 is turned off, but the parasitic body diode is turned on, the drain voltage Vdrain of the primary side power switch 44 approaches 0 potential, and if the primary side power switch 44 is turned on, the zero voltage is turned on. At time t2, the primary side power switch 44 is turned on at zero voltage, the IP is turned from negative to positive, and the input IN starts to store energy to the transformer 47 and transfer the energy to the output OUT at time t 3.
Based on the switching power supply quick charging system, the invention also provides a non-coupler secondary side control method, which comprises the following steps:
The protocol detection unit detects a protocol terminal in an output port to obtain voltage and current information, generates a constant voltage level CV_REF and a constant current level CC_REF according to the voltage and current information, and transmits the constant voltage level CV_REF and the constant current level CC_REF to the constant voltage control unit and the constant current control unit respectively;
the constant voltage control unit directly samples the secondary side output voltage and compares the secondary side output voltage with a constant voltage level CV_REF to generate a constant voltage control signal CV_EN;
The constant current control unit directly samples the secondary side output current or indirectly calculates the secondary side output current, and generates a constant current control signal CC_EN based on a constant current level CC_REF;
The primary side switching-ON signal transmitting unit generates a switching-ON signal PRI_ON according to a constant voltage control signal CV_EN and a constant current control signal CC_EN and transmits the switching-ON signal PRI_ON to the secondary side driving control unit, the secondary side driving control unit controls the additional switching-ON of the secondary side power switching tube for a preset time, and switching-ON information is transmitted to the primary side controller through transformer coupling;
The primary side turn-ON signal receiving unit detects the common terminal voltage of the voltage dividing resistor coupled to the third winding of the transformer, and generates a turn-ON signal PRI_ON_EN of the primary side power switching tube after detecting the turn-ON information sent by the secondary side so as to control the turn-ON of the primary side power switching tube and realize the secondary side control of the optoless coupler.
When the constant voltage control signal cv_en and the constant current control signal cc_en are both 1, the and gate output EN of the primary side turn-ON signal transmitting unit is 1, the trigger is set to 1, and the pulse width control unit starts timing, and the trigger is set to 0 once the timing is finished, the output pri_on of the trigger is the pulse width, the turn-ON signal pri_on is transmitted to the secondary side driving control unit, the pulse width of the secondary side power tube is controlled to be additionally turned ON, and the additional conduction is coupled to the third winding of the transformer through the transformer, so that the transmission process of the turn-ON information is completed.
When the output EN of the and gate is 1, the second switch is closed, the current source starts to charge the second capacitor, and when the voltage of the second capacitor is charged to above the third level Vref3, the output Tstop of the second comparator is 1, the trigger of the primary side turn-ON signal transmitting unit is set to 0, and the turn-ON signal pri_on is ended.
Before the secondary side sends out the opening information, the voltage PRI_ON_DET of the first capacitor in the primary side opening signal receiving unit is always lower than the second level Vref2, PRI_ON_EN is always kept 0, after the secondary side sends out the opening information, PRI_ON_DET is charged to the second level Vref2, the opening signal PRI_ON_EN output by the first comparator is changed to 1, the opening signal PRI_ON_EN is transmitted to the primary side driving control unit, and the primary side power switch tube is immediately opened after the secondary opening information is sent out.
The switching power supply quick-charging system and the non-coupler secondary side control method thereof do not need optocouplers and special packages, have low cost, and have high precision because constant voltage and constant current are directly detected and controlled on the secondary side. Meanwhile, the short-time turn-on signal sent by the secondary side can enable the primary side power switch tube to be turned on easily at zero voltage.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, which are intended to facilitate an understanding of the principles and concepts of the invention and are to be varied in scope and detail by persons of ordinary skill in the art based on the teachings herein. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (9)
1. A switching power supply quick charge system, comprising:
An input port coupled to an ac input voltage VAC;
a first rectifier coupled to the input port for converting the ac voltage to a dc voltage;
An input capacitor coupled to the first rectifier for filtering the dc voltage output by the first rectifier;
An output capacitor coupled to the output port;
an output port for providing voltage and current to a load, comprising protocol terminals;
The transformer comprises a first winding, a second winding and a third winding, wherein the first winding is coupled to an input capacitor and a primary side power switch tube;
A primary side power switching tube coupled to the primary side controller, the transformer first winding and the primary side current sense resistor;
a secondary side power switch tube coupled to the secondary side controller and the transformer second winding;
a primary side controller including a primary side drive control unit, a primary side on signal receiving unit, and a current peak control unit;
the primary side drive control unit is used for controlling the ON and off of the primary side power switch tube, the ON signal PRI_ON_EN of the primary side power switch tube is obtained from the primary side ON signal receiving unit, and the off signal is generated by the current peak value control unit;
The primary side turn-ON signal receiving unit is used for detecting turn-ON information sent by the secondary side by detecting the common terminal voltage of the voltage dividing resistor, and generating a turn-ON signal PRI_ON_EN of the primary side power switching tube so as to control the turn-ON of the primary side power switching tube;
The current peak value control unit is used for detecting the current flowing through the primary side current detection resistor and comparing the current peak value with a current peak value level so as to control the peak value of the primary side current;
the secondary side controller comprises a synchronous rectification driving control unit, a primary side opening signal transmitting unit, a protocol detecting unit, a constant voltage control unit, a constant current control unit and a secondary side driving control unit;
The synchronous rectification drive control unit is used for controlling the secondary side power switch tube to be turned ON when the transformer demagnetizes and rectifies by detecting the drain voltage of the secondary side power switch tube and generating a drive signal SR_ON;
The primary side turn-ON signal sending unit is used for generating a primary side turn-ON signal PRI_ON according to a constant voltage control signal CV_EN and a constant current control signal CC_EN output by the constant voltage control unit and the constant current control unit, transmitting the primary side turn-ON signal PRI_ON to the secondary side driving control unit so as to control the turn-ON of the secondary side power switching tube except for the extra preset time during rectification, and then transmitting turn-ON information to the primary side through transformer coupling;
the protocol detection unit is used for communicating with the load end through a protocol terminal of the detection output port, obtaining voltage and current information output by the load end through a detection protocol, generating a constant voltage level CV_REF and transmitting the constant voltage level CV_REF to the constant voltage control unit, and generating a constant current level CC_REF and transmitting the constant current level CC_REF to the constant current control unit;
The constant voltage control unit is used for directly sampling the secondary side output voltage and comparing the secondary side output voltage with a constant voltage level CV_REF to generate a constant voltage control signal CV_EN;
The constant current control unit is used for directly sampling the secondary side output current or indirectly calculating the secondary side output current to generate a constant current control signal CC_EN;
The secondary side drive control unit is used for controlling the ON and off of the secondary side power switch tube according to the drive signal SR_ON of the synchronous rectification drive control unit and the primary side ON signal PRI_ON of the primary side ON signal transmitting unit;
The primary side turn-on signal receiving unit comprises a first voltage-controlled current source, a second voltage-controlled current source, a DEMAG unit, a first switch, a first comparator and a first capacitor, wherein a common end of a divider resistor is coupled to an input end of the DEMAG unit, a control end of the first voltage-controlled current source and a control end of the second voltage-controlled current source, an output end of the first voltage-controlled current source, a second port of the first switch and a first input port of the first comparator are all coupled to a first port of the first capacitor, the first port of the first switch is coupled to a first level Vref1, the control port of the first switch is coupled to an output end of the DEMAG unit, the second input port of the first comparator is coupled to a second level Vref2, and an output end of the first comparator serving as an output end of the primary side turn-on signal receiving unit is coupled to the primary side driving control unit.
2. The switching power supply quick charge system according to claim 1, wherein the constant current control unit directly detects a voltage of the output current detection resistor and compares the detected voltage with a constant current level cc_ref to generate a constant current control signal cc_en.
3. The switching power supply fast charging system according to claim 1, wherein the constant current control unit controls the output current IO by controlling the switching period TSW to generate the constant current control signal cc_en by using a formula of io= (1/2) IPK NPS TONS/TSW, wherein IPK is a peak value of the primary side current, NPS is a turn ratio of the first winding and the second winding of the transformer, and TONS is a rectifying time of the secondary side power switching tube.
4. The switching power supply quick charge system according to claim 1, wherein the primary side turn-on signal transmitting unit comprises an and gate, a pulse width control unit and a trigger, wherein a first input port and a second input port of the and gate are respectively coupled to an output end of the constant voltage control unit and an output end of the constant current control unit, an output end of the and gate is coupled to an input end of the pulse width control unit and a second input port of the trigger, an output end of the pulse width control unit is coupled to a first input port of the trigger, and an output end of the trigger is coupled to the secondary side driving control unit as an output end of the primary side turn-on signal transmitting unit.
5. The switching power supply quick charge system according to claim 4, wherein the pulse width control unit comprises a current source, a second switch, a second capacitor and a second comparator, wherein an output terminal of the current source is coupled to a first port of the second switch, a second port of the second switch and a first port of the second capacitor are coupled to a first input port of the second comparator, a control terminal of the second switch is coupled to an output terminal of an AND gate in the primary side on signal transmission unit, a second port of the second capacitor is coupled to ground, a second input port of the second comparator is coupled to a third level, and an output terminal of the second comparator is coupled as an output terminal of the pulse width control unit to a first input port of a trigger of the primary side on signal transmission unit.
6. A non-coupling secondary side control method applied to the switching power supply quick charging system of claim 1, wherein the non-coupling secondary side control method detects and controls output voltage and current at a secondary side, and the secondary side transmits turn-on information to a primary side through transformer coupling, comprising:
The protocol detection unit detects a protocol terminal in an output port to obtain voltage and current information, generates a constant voltage level CV_REF and a constant current level CC_REF according to the voltage and current information, and transmits the constant voltage level CV_REF and the constant current level CC_REF to the constant voltage control unit and the constant current control unit respectively;
the constant voltage control unit directly samples the secondary side output voltage and compares the secondary side output voltage with a constant voltage level CV_REF to generate a constant voltage control signal CV_EN;
The constant current control unit directly samples the secondary side output current or indirectly calculates the secondary side output current, and generates a constant current control signal CC_EN based on a constant current level CC_REF;
The primary side switching-ON signal transmitting unit generates a switching-ON signal PRI_ON according to a constant voltage control signal CV_EN and a constant current control signal CC_EN and transmits the switching-ON signal PRI_ON to the secondary side driving control unit, the secondary side driving control unit controls the additional switching-ON of the secondary side power switching tube for a preset time, and switching-ON information is transmitted to the primary side controller through transformer coupling;
The primary side turn-ON signal receiving unit detects the common terminal voltage of the voltage dividing resistor coupled to the third winding of the transformer, and generates a turn-ON signal PRI_ON_EN of the primary side power switching tube after detecting the turn-ON information sent by the secondary side so as to control the turn-ON of the primary side power switching tube and realize the secondary side control of the optoless coupler.
7. The method according to claim 6, wherein when the constant voltage control signal cv_en and the constant current control signal cc_en are both 1, the and gate output EN of the primary side turn-ON signal transmitting unit is 1, the trigger is set to 1, and the pulse width control unit starts to count time, and the trigger is set to 0, the output pri_on of the trigger is the pulse width, the turn-ON signal pri_on is transmitted to the secondary side driving control unit, and the secondary side power tube is controlled to be additionally turned ON by the pulse width, and the additional turn-ON is coupled to the third winding of the transformer through the transformer, so that the transmission process of the turn-ON information is completed.
8. The method of claim 7, wherein when the and gate output EN is 1, the second switch is turned ON, the current source starts charging the second capacitor, and when the second capacitor voltage is charged above the third level Vref3, the second comparator output Tstop is 1, the flip-flop of the primary side ON signal transmitting unit is set to 0, and the ON signal pri_on is terminated.
9. The method according to claim 7, wherein the voltage PRI_ON_DET of the first capacitor in the primary-side ON signal receiving unit is always lower than the second level Vref2 before the secondary side sends the ON information, PRI_ON_DET is always maintained to be 0, the PRI_ON_DET is charged to be above the second level Vref2 after the secondary side sends the ON information, the ON signal PRI_ON_EN output by the first comparator becomes 1, the ON signal PRI_ON_EN is transmitted to the primary-side drive control unit, and the primary-side power switching tube is turned ON immediately after the secondary-side ON information is sent.
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| CN106533214B (en) * | 2016-12-21 | 2023-03-14 | 无锡硅动力微电子股份有限公司 | Control circuit and control method of switching power supply converter |
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