CN114759809A

CN114759809A - Switching power supply and method for use in a switching power supply

Info

Publication number: CN114759809A
Application number: CN202210503978.4A
Authority: CN
Inventors: 张秀红; 史献冰; 王伟华; 方烈义
Original assignee: On Bright Electronics Shanghai Co Ltd
Current assignee: On Bright Electronics Shanghai Co Ltd
Priority date: 2022-05-10
Filing date: 2022-05-10
Publication date: 2022-07-15
Also published as: TW202345506A

Abstract

The embodiment of the invention provides a switching power supply and a method for using the same. The switching power supply provided by the embodiment of the invention comprises: the secondary side synchronous rectification and protocol control chip is configured to obtain coding information by coding request information from the equipment to be charged; and the primary side feedback control chip is configured to decode the coded information to obtain request information, perform authenticity verification on the request information, send confirmation information to the secondary side when the request information passes the authenticity verification, and control the switching power supply to provide an output signal for the equipment to be charged based on the request information. According to the technical scheme, an isolation optocoupler or a capacitor is omitted, and meanwhile, the primary side responds to the secondary side after the authenticity of the request information is verified, so that the secondary side is informed that the request information received by the primary side is correct, the system cost is reduced, data communication information interaction can be realized on the charger side, and the requirements of low cost and miniaturization of a charging product can be met.

Description

Switching power supply and method for use in a switching power supply

Technical Field

The invention belongs to the field of integrated circuits, and particularly relates to a switching power supply and a method for using the same in the switching power supply.

Background

In recent years, a primary-side feedback-controlled power supply (e.g., a flyback power supply) has been widely used in the field of charging of devices to be charged (e.g., mobile terminal devices) due to its characteristics of low circuit cost, low standby power consumption, and small size. In the working process of the primary side feedback control flyback power supply, a primary side control chip needs to adjust information such as output voltage and current of a switch power supply in real time according to voltage or current request information requested by mobile terminal equipment.

However, the optical coupler communication rate is relatively low, and is greatly influenced by temperature, the standby power consumption is large, the size is large, the system cost and the volume are increased, and the optical coupler communication rate is obviously not an optimal solution for low-cost consumer charging equipment. Although the capacitive digital isolation method has small size and low power consumption, noise and communication signals share one transmission channel, so that the interference resistance is poor, the manufacturing cost is high, and the like.

Meanwhile, an optical coupler device or a capacitor is used for isolation to transmit information, after the primary side receives feedback information of the secondary side, if errors exist in decoding or encoding, the secondary side cannot attempt to transmit encoded information for two or more times, and only one-way communication of the primary side transmitted by the secondary side is achieved.

Disclosure of Invention

The embodiment of the invention provides a switching power supply and a method for using the same, which are characterized in that request information from equipment to be charged is coded to obtain coded information, the coded information is decoded to obtain the request information, the switching power supply is controlled to provide output control for the equipment to be charged based on the request information, an isolation optocoupler or a capacitor used for information transmission in a traditional system is omitted, a low-cost and high-reliability mode of communication from a secondary side to a primary side and authenticity verification from the primary side to the secondary side is provided, the system cost is reduced, and the miniaturization requirement for a charging product can be met.

In one aspect, an embodiment of the present invention provides a switching power supply, configured to charge a device to be charged, including: the secondary side synchronous rectification and protocol control chip is configured to obtain coding information by coding request information from the equipment to be charged; and the primary side feedback control chip is configured to decode the coded information to obtain the request information, perform authenticity verification on the request information, send confirmation information to the secondary side synchronous rectification and protocol control chip under the condition that the request information passes the authenticity verification, and control the switching power supply to provide an output signal for the equipment to be charged based on the request information.

In another aspect, an embodiment of the present invention provides a method for use in a switching power supply, where the method is used to charge a device to be charged, the switching power supply includes a secondary synchronous rectification and protocol control chip and a primary feedback control chip, and the method includes: encoding the request information from the equipment to be charged by utilizing the secondary side synchronous rectification and protocol control chip to obtain encoded information; and decoding the coded information by using the primary side feedback control chip to obtain the request information, performing authenticity verification on the request information, sending confirmation information to the secondary side synchronous rectification and protocol control chip under the condition that the request information passes the authenticity verification, and controlling the switching power supply to provide an output signal for the equipment to be charged based on the request information.

The switching power supply and the method for using the same provided by the embodiment of the invention have the advantages that an isolation optocoupler or a capacitor is omitted, a low-cost and high-reliability method for verifying the authenticity of the secondary side to the primary side communication and the primary side to the secondary side is provided, the system cost is reduced, and the miniaturization requirement for a charging product can be met.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 shows a schematic structure diagram of a prior art optocoupler-isolated switching power supply;

fig. 2 shows a schematic diagram of a prior art capacitive isolated switching power supply;

fig. 3 is a schematic structural diagram of a switching power supply provided by an embodiment of the invention;

fig. 4 is a schematic structural diagram illustrating a specific implementation manner of a switching power supply according to an embodiment of the present invention;

fig. 5 is a waveform diagram illustrating corresponding signals in the switching power supply provided by the embodiment of the invention;

fig. 6 is a schematic structural diagram illustrating a primary side feedback control chip according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram illustrating a secondary side synchronous rectification and protocol control chip according to an embodiment of the present invention;

FIG. 8 is a waveform diagram illustrating an encoding duty cycle and a normal duty cycle provided by an embodiment of the present invention;

fig. 9 shows a corresponding code provided by an embodiment of the present invention when a device to be charged requests to output a voltage of 9V;

FIG. 10 shows the corresponding codes provided by the embodiment of the present invention when the device to be charged requests to output a voltage/current of 9V/2A;

fig. 11 shows a code corresponding to a current device to be charged when the device to be charged is pulled out according to an embodiment of the present invention;

fig. 12 is a graph illustrating waveforms involved in a primary-secondary communication response mechanism implemented between a verification module of a primary feedback control chip and a confirmation module of a secondary synchronous rectification and protocol control chip according to an embodiment of the present invention; and

fig. 13 is a flow chart illustrating a method for use in a switching power supply according to an embodiment of the present invention.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.

It should be noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

For better reasons of the switching power supply provided by the embodiment of the present invention, the switching power supply provided by the prior art will be described first.

Fig. 1 shows a schematic structural diagram of an optocoupler-isolated switching power supply provided in the prior art, and as shown in fig. 1, the switching power supply mainly includes an EMI filter 110, a primary feedback control chip 120, a secondary synchronous rectification and protocol control chip 130, a USB/TYPE-C interface 140, an optocoupler, and the like.

As shown in the figure, the switch power supply adopts an optical coupler isolation mode, the optical coupler communication rate is relatively low, the temperature influence is large, the standby power consumption is large, the size is large, the system cost and the volume are increased, and the switch power supply is obviously not an optimal solution for low-cost consumer charging equipment.

Fig. 2 shows a schematic structural diagram of a capacitive isolation TYPE switching power supply provided in the prior art, and as shown in fig. 2, the switching power supply mainly includes an EMI filter 210, a primary side feedback control chip 220, a secondary side synchronous rectification and protocol control chip 230, a USB/TYPE-C interface 240, a capacitor, and the like.

As shown in the figure, the switching power supply adopts a capacitive isolation mode, and although the capacitive digital isolation has small size and low power consumption, noise and communication signals share one transmission channel, so that the interference resistance is poor, the manufacturing cost is high, and obviously, the capacitive digital isolation is not an optimal solution for low-cost consumer charging equipment.

In order to solve the problems in the prior art, the embodiment of the invention provides a switching power supply. The switch power supply provided by the embodiment of the invention cancels an isolation optocoupler or a capacitor, can realize a communication mode from a secondary side to a primary side with low cost and high reliability, reduces the system cost and realizes the miniaturization of a charging product. The following describes a switching power supply provided in an embodiment of the present invention.

Fig. 3 shows a schematic structural diagram of a switching power supply provided in an embodiment of the present invention. As shown in fig. 3, the switching power supply mainly includes an EMI filter 310, a primary feedback control chip 320, a secondary synchronous rectification and protocol control chip 330, a USB/TYPE-C interface 340, a transformer T1 (including a primary winding Npri, a secondary winding Nsec, and an auxiliary winding Naux), and an output module 350 (optional), where the output module 350 may include an output switch.

As an example, the secondary synchronous rectification and protocol control chip 330 may be configured to encode the request information from the device to be charged, resulting in encoded information; the primary feedback control chip 320 may be configured to decode the encoded information to obtain the request information, and control the switching power supply to provide the output signal to the device to be charged based on the request information.

Specifically, the switching power supply provided in the embodiment of the present invention cancels an isolation optocoupler or a capacitor, obtains encoded information by encoding request information from a device to be charged inside the secondary side synchronous rectification and protocol control chip 330, transmits the encoded information to the primary side feedback control chip 320 via the auxiliary winding Naux of the transformer T1 and the CS pin of the primary side feedback control chip 320, decodes the encoded information inside the primary side feedback control chip 320 to obtain the request information, performs authenticity check on the request information, sends confirmation information to the secondary side after the request information passes the check, and controls the switching power supply to provide an output signal to the device to be charged based on the request information. Therefore, embodiments of the present invention provide a communication apparatus and method for transmitting a signal from a secondary side to a primary side, verifying authenticity of request information at a primary side feedback control chip, responding to a secondary side synchronous rectification and protocol control chip after verification to notify the secondary side synchronous rectification and protocol control chip that the primary side feedback control chip receives correct request information, and providing an output signal to a device to be charged based on the request information by using the primary side feedback control chip.

As shown in fig. 3, when a device to be charged (e.g., a smart phone, etc.) needs to be charged quickly, request information for performing voltage or current regulation is provided to the secondary synchronous rectification and protocol control chip 330 through the DP, DN or CC1, CC2 of the USB/TYPE-C interface 340, the secondary synchronous rectification and protocol control chip 330 receives the request information, the request information is encoded through an internal encoding module (which will be described below), and the encoded information is provided to the primary feedback control chip 320, the primary feedback control chip 320 receives the encoded information, the encoded information is decoded through an internal decoding module (which will be described below), so as to obtain the request information, and the request information is verified to be true or false, and confirmation information indicating that the request information is verified is sent to the secondary synchronous rectification and protocol control chip after the request information is verified, and the primary side feedback control chip is used for controlling the switching power supply to provide expected high output voltage, current or protection and the like for the equipment to be charged based on the request information, so that the aim of quick charging is fulfilled.

In order to better understand the switching power supply provided in the embodiment of the present invention, a specific implementation of the switching power supply is described below, and with reference to fig. 4, fig. 4 shows a schematic structural diagram of the specific implementation of the switching power supply provided in the embodiment of the present invention.

As shown in fig. 4, the switching power supply mainly includes an EMI filter 310, a rectifier bridge BD, an input capacitor Cbulk, a primary feedback control chip 320, a primary current sampling resistor Rs, a secondary synchronous rectification and protocol control chip 330, a USB/TYPE-C interface 340, a transformer T1 (including a primary winding Npri, a secondary winding Nsec, and an auxiliary winding Naux), an output capacitor Co, and an output module 350 (optional), where the output module 350 may include an output switch.

In some embodiments, the primary feedback control chip 320 may include a power switch Q1, and the secondary synchronous rectification and protocol control chip 330 may include a synchronous rectification switch Q2. The above is provided as an example only and should not be construed as limiting, for example, in other embodiments the power switches Q1 and Q2 may be independently packaged.

As an example, the primary side feedback control chip 320 may be configured to start operating when an input characterizing signal characterizing an input voltage of the switching power supply is greater than a first preset threshold; the secondary synchronous rectification and protocol control chip 330 may be configured to start operating when an output feedback signal representing an output voltage of the switching power supply is greater than a second preset threshold.

Specifically, as shown in the figure, when the AC Voltage is switched in, it is filtered and rectified by the EMI filter 310 and the rectifier bridge BD, then the input capacitor Cbulk is charged by the filtered and rectified Voltage, the filtered AC Voltage is rectified into a dc Voltage by the rectifier bridge BD, the capacitor Cd is charged by the dc Voltage through the starting resistor Rst, and then after the Voltage on the capacitor Cd (i.e., the Voltage at the VDD pin of the primary side feedback control chip 320) is higher than the Under Voltage protection (UVLO) Voltage set by the primary side feedback control chip 320, the primary side feedback control chip 320 starts to operate to output energy to the secondary side, the body diode D1 inside the secondary side synchronous rectification and protocol lo control chip 330 is turned on, so that the output Voltage Vo of the switching power supply starts to rise, after the output Voltage Vo is higher than the uvvoltage set by the secondary side synchronous rectification and protocol control chip 330, the secondary synchronous rectification and protocol control chip 330 starts to operate.

As an example, the normal operation flow of the flyback switching power supply provided in the embodiment of the present invention may be mainly divided into the following stages:

in the first phase, during the on-time of the power switch Q1, energy is stored in the primary winding Npri of the transformer T1, and the secondary winding is supplied with energy from the output capacitor Co.

In the second stage, when the power switch Q1 is changed from the on state to the off state, the synchronous rectification switch Q2 is controlled to be changed from the off state to the on state, and during the period that the synchronous rectification switch Q2 is in the on state, the energy stored in the primary winding Npri of the transformer T1 is released to the secondary winding of the transformer T1 (which corresponds to the demagnetization time tdemeg) to provide energy for the load and charge the output capacitor Co; at this time, the voltage across the auxiliary winding Vaux of the transformer T1 can reflect the output voltage Vo (the voltage drop is negligible here because the synchronous rectification on-resistance is small), and an output feedback signal VFB (which may represent the output voltage Vo) obtained by dividing the voltage Vaux across the auxiliary winding Naux by the resistors R1 and R2 is used as a feedback control signal and is input to the primary side feedback control chip 320 via the FB pin for control.

In the third stage, after the synchronous rectification switch Q2 changes from the on state to the off state, the inductor Lmi of the primary winding Npr of the transformer T1 and the output capacitor Coss of the power switch Q1 resonate (corresponding to the resonant time Tring), and according to the difference of the output load, the primary feedback control chip 320 may control the power switch Q1 to change from the off state to the on state at different resonant valley bottoms, and repeatedly cycle the above three processes, and finally provide the desired output voltage, output current and/or protection for the device to be charged through the USB/Type-C interface 340.

With reference to fig. 4 and fig. 5, fig. 5 shows waveforms of corresponding signals in the switching power supply provided by the embodiment of the present invention.

Wherein, the waveform PSR gate represents a control signal of the primary side feedback control chip 320 for controlling on/off of the power switch Q1, the waveform PSR Ipk represents a current flowing through the primary side winding (hereinafter referred to as primary side current), the waveform PSR FB represents an output feedback signal for representing an output voltage, the waveform SR Vdrain represents a voltage at the drain of the synchronous rectification switch Q2 in the secondary side synchronous rectification and protocol control chip 330, the waveform SR gate represents a control signal of the secondary side synchronous rectification and protocol control chip 330 for controlling on/off of the synchronous rectification switch Q2, the waveform SR Isk represents a current flowing through the secondary side winding (hereinafter referred to as secondary side current), Tdemg corresponds to demagnetization time, and Tring corresponds to resonance time. The correspondence between the waveforms of the respective signals is shown in fig. 5, and is not described herein again for the sake of simplifying the description.

In summary, the switching power supply provided by the embodiment of the present invention receives the request information from the device to be charged through the signals DP, DN or CC1, CC2 of the USB/TYPE-C interface 340, and then the charger may adjust the output voltage or output current or implement protection, etc. based on the request information.

Specifically, the encoding module built in the secondary side synchronous rectification and protocol control chip 330 may encode the request information based on a predetermined encoding rule, form specific pre-encoded information, then, the specific pre-encoded information is provided to the primary side feedback control chip 320 through the auxiliary winding of the transformer and the current detection circuit (refer to fig. 6), and a decoding module built in the primary side feedback control chip 320 can decode the specific pre-encoded information to obtain the requested information, and the request information is verified according to the preset information, and after the request information passes the verification, the primary side feedback control chip can be informed to the secondary side synchronous rectification and protocol control chip that the correct request information is received, and regulating an output signal by using the primary side feedback control chip according to the decoded request information, wherein the output signal can comprise one or more of the following items: output voltage, output current, protection signal, etc.

For better understanding of the operation principle of the switching power supply provided by the embodiment of the present invention, a specific implementation of the primary side feedback control chip 320 of the switching power supply shown in fig. 3 and 4 is described below by way of specific example. Referring to fig. 6, fig. 6 shows a schematic structural diagram of a primary side feedback control chip according to an embodiment of the present invention.

As shown in fig. 6, the primary feedback control chip 320 may include a VDD pin, an FB pin, a GND pin, a CS pin, a Drain pin, and the like, and may include a UVLO and AVDD module 3202, a reference signal generation module 3204, a protection module 3206, a sampling module 3208, a demagnetization detection module 3210, a constant voltage control module 3212, a current detection module 3214, a decoding module 3216, a constant current control module 3218, a verification module 3220, a logic control module 3222, a gate driving module 3224, and the like.

As an example, a first terminal of the UVLO and AVDD block 3202 is connected to a VDD pin, a second terminal is connected to a first terminal of the reference signal generation block 3204, a third terminal may output a Power Good (PG) signal, a second terminal of the reference signal generation block 3204 may output a reference voltage Vref, a first terminal of the protection block 3206 is connected to the FB pin, a second terminal of the protection block 3206 is connected to a first terminal of the logic control block 3222, a first terminal of the sampling block 3208 is connected to the FB pin, a second terminal of the sampling block 3208 is connected to a first terminal of the constant voltage control block 3212, a second terminal of the constant voltage control block 3212 receives Vref _ cv, a first terminal of the demagnetization detection block 3210 is connected to the FB pin, a second terminal of the demagnetization detection block 3210 is connected to a first terminal of the constant current control block 3218, a first terminal of the current detection block 3214 is connected to the third terminal of the constant voltage control block 3212, a third terminal of the current detecting module 3214 is connected to the second terminal of the constant current control module 3218, a fourth terminal of the current detecting module 3214 is connected to the first terminal of the decoding module 3216, a second terminal of the decoding module 3216 is connected to the third terminal of the constant current control module 3218, a third terminal of the decoding module 3216 is connected to the second terminal of the demagnetization detecting module 3210, the first terminal of the constant current control module 3218 and the fourth terminal of the constant voltage control module 3212, a fourth terminal of the decoding module 3216 is connected to the fifth terminal of the constant voltage control module 3212, a sixth terminal of the constant voltage control module 3212 is connected to the second terminal of the logic control module 3222, a fourth terminal of the constant current control module 3218 is connected to the third terminal of the logic control module 3222, a fifth terminal of the decoding module 3216 is connected to the fourth terminal of the logic control module 3222, a sixth terminal of the decoding module 3216 is connected to the third terminal of the protection module 3206, and a fifth terminal of the logic control module 3222 is connected to the first terminal of the gate driving module 3224, the seventh terminal of the decoding module 3216 is connected to the first terminal of the verifying module 3220, the second terminal of the verifying module 3220 is connected to the sixth terminal of the logic control module 3222, the second terminal of the gate driving module 3224 is connected to the first terminal of the power switch Q1 and the fifth terminal of the current detecting module 3214, the second terminal of the power switch Q1 is connected to the Drain pin, and the third terminal of the power switch Q1 is connected to the CS pin.

As an example, the UVLO and AVDD block 3202 may be configured to provide an operating voltage and an internal reference voltage Vref, etc. to the primary side feedback control chip 320, wherein, after the VDD voltage exceeds the UVLO voltage, the PG signal may be set to 1, so that various blocks built in the primary side feedback control chip 320 may start to operate.

As one example, the reference signal generation module 3204 may be used to output the reference voltage Vref _ cv to the constant voltage control module 3212.

As an example, the protection module 3206 may be configured to perform protection based on the request information from the decoding module 3216, and the like, and specifically, such protection mainly consists of two parts, and one part may be detection protection based on the signal from the FB pin, such as voltage dividing resistor open/short circuit, FB pin open/short circuit protection, auxiliary winding open circuit protection, and the like; another part may be protection based on decoded information from the decoding module, e.g. protection of conditions such as output voltage over-voltage, under-voltage, open and/or short circuits, etc.

As an example, the demagnetization detecting module 3210 may be configured to detect a demagnetization condition of the primary winding of the transformer based on the output feedback signal when the power switching transistor Q1 is in the off state.

Specifically, the demagnetization detecting module 3210 may be further configured to determine, when the power switch Q1 is in an off state, a time period from a rising edge of the output feedback signal rising above a certain preset value (e.g., 0.1V) to a falling edge of the output feedback signal falling below a certain preset value (e.g., 0.1V), as the demagnetization time Tdemg of the primary winding (see fig. 5).

As an example, the sampling module 3208 may be configured to sample and hold the platform voltage of the output feedback signal of the current cycle until the next cycle during the demagnetization time of the primary winding, and input the sampled voltage Vs to the constant voltage control module 3212.

As an example, the constant voltage control module 3212 may be configured to generate a first control signal for controlling on and off of the power switch Q1 based on the sampled voltage Vs and a voltage signal Vcs representing a primary current.

Specifically, the first terminal of the constant voltage control module 3212 receives the sampling voltage Vs from the sampling module 3208, the second terminal receives the reference voltage Vref _ cv (the reference voltage Vref includes the reference voltage Vref _ cv), the constant voltage control module 3212 may be internally provided with an error amplifier EA for controlling core operation, wherein the sampling voltage Vs may be input to a negative input terminal of the error amplifier EA (the first terminal of the constant voltage control module 3212), the reference voltage Vref _ cv may be input to a positive input terminal of the error amplifier EA (the second terminal of the constant voltage control module 3212), and the two voltages are error-amplified to obtain an error signal UEA, the constant voltage control module 3212 may be internally provided with a Pulse Width Modulation (PWM) module for Pulse Width modulating the error signal UEA and a voltage signal Vcs (Vcs ═ ips ═ Rsense) representing the primary side current Ipk to control the on-time of the power switching tube Q1, so that the output feedback signal VFB follows the reference voltage variations as the input Bulk voltage and load vary.

As an example, the current detection module 3214 may be configured to detect the primary current Ipk, including a positive current detection and a negative current detection.

Specifically, when the power switch Q1 is turned on, the primary side current Ipk is a forward current, and the current flows through the input capacitor Cbulk, the primary side winding Npri of the transformer, the power switch Q1, and the current detection resistor Rs to ground, and the current detection module 3214 may be configured to detect the magnitude and width of the forward current, and send the detection result to the constant voltage control module 3212 and the constant current control module 3218.

As an example, the constant voltage control module 3212 may be configured to receive a demagnetization condition and a forward current detection result to control the switching power supply to provide a constant voltage to the device to be charged, and the constant current control module 3218 may be configured to receive the demagnetization condition and the forward current detection result to control the switching power supply to provide a constant current to the device to be charged.

Specifically, after the demagnetization of the primary winding is finished, the primary current Ipk is a negative current, the current flows through the ground, the current detection resistor Rs, the parasitic capacitor of the power switch tube Q1, and the primary winding Npri of the transformer to the input capacitor Cbulk, and the current detection module 3214 may be configured to detect the magnitude and width of the negative current, and send the detection result to the decoding module 3216.

As an example, the decoding module 3216 may be configured to receive the demagnetization and the negative current detection result, and decode the encoded information transmitted by the secondary side according to a preset rule to obtain the request information. Then, the output voltage and the output current are controlled or protected according to the request information obtained by decoding, and the decoded information is sent to the verifying module 3220 for verifying authenticity.

Specifically, the constant voltage control module 3212 may be configured to control the switching power supply to output a constant voltage to the device to be charged based on the voltage request information in the decoded request information, the constant current control module 3218 may be configured to control the switching power supply to output a constant current to the device to be charged based on the current request information in the decoded request information, and the protection module 3206 may be configured to control overvoltage, undervoltage, open circuit, short circuit protection, and the like of the output voltage provided by the switching power supply to the device to be charged based on the protection request information in the decoded request information.

As an example, the constant current control module 3218 may be configured to output a constant current in a constant current mode based on the current detection signal, and the magnitude of the constant current may be adjusted by the external current detection resistor Rsense. Specifically, the constant current control module 3218 may receive the forward current to perform current control when the power switch Q1 is turned on, receive the decoding information from the decoding module 3216 after demagnetization is completed, and perform current control according to the decoding information.

As an example, the verifying module 3220 may be configured to, after the decoding module decodes the encoded information from the secondary synchronous rectification and protocol control chip to obtain the request information, perform an authenticity verification on the request information according to the preset information, and after the request information passes the verification, send confirmation information indicating that the request information passes the verification to the secondary synchronous rectification and protocol control chip to notify the secondary synchronous rectification and protocol control chip that the primary feedback control chip receives the correct request information.

As an example, the logic control module 3222 may be configured to logically analyze various input signals and output logic control signals to the gate driving module 3224.

As an example, the gate driving module 3224 may be configured to control logic such that the signals realize totem output.

Specifically, the gate driving module 3224 may be configured to process the signal from the logic control module 3222 and generate a control signal for controlling the on and off of the power switch Q1. The second terminal of the power switch Q1 may be connected to the Drain pin, and the third terminal may be connected to the CS pin.

It should be noted that, besides the power switch Q1 can be located inside the primary feedback control chip as shown in the figure, the power switch Q1 can also be packaged separately, and the invention is not limited to this.

In order to better understand the working principle of the switching power supply provided by the embodiment of the present invention, a specific implementation manner of the secondary synchronous rectification and protocol control chip 330 of the switching power supply shown in fig. 3 and fig. 4 is described below by way of specific examples. Referring to fig. 7, fig. 7 illustrates a schematic structural diagram of a secondary synchronous rectification and protocol control chip according to an embodiment of the present invention.

As shown in fig. 7, the secondary side synchronous rectification and protocol control chip 330 mainly includes a Vin pin, a VDD pin, a DP pin, a DN pin, a CC1 pin, a CC2 pin, a GND pin, a Drain pin, and the like, and may include a synchronous rectification module 3302, a regulator 3304, a regulator 3306, a UVLO module 3308, a system output detection module 3310, an encoding module 3312, a dummy load module 3314, a protection module 3316, a demagnetization detection module 3318, a confirmation module 3320, a synchronous rectification switch tube Q2, and the like. The synchronous rectification module 3302 may include an HV switch, a comparator 3322, a comparator 3324, a minimum on-time setting module 3326, an RS flip-flop 3328, a logic control module 3330, a gate driving module 3332, and the like.

As an example, a first terminal of the synchronous rectification module 3302 is connected to a first terminal of the synchronous rectification switch Q2, a second terminal of the synchronous rectification switch Q2 is connected to a Drain pin, a third terminal of the synchronous rectification switch Q2 is connected to a GND pin, a first terminal of the demagnetization detection module 3318 is connected to the Drain pin, a second terminal of the synchronous rectification module 3302 is connected to a second terminal of the synchronous rectification module 3312, a first terminal of the coding module 3312 is connected to a first terminal of the dummy load module 3314, a second terminal of the dummy load module 3304 is connected to a third terminal of the synchronous rectification module 3302, a first terminal of the regulator 3304 is connected to a Vin pin, a second terminal of the system output detection module 3310 is connected to a first terminal of the system output detection module 3310, a second terminal of the system output detection module 3310 is connected to a fourth terminal of the synchronous rectification module 3302, a second terminal of the coding module 3312 is connected to a fifth terminal of the synchronous rectification module 3302, the fourth terminal of the encoding module 3312 is connected to the first terminal of the protection module 3316, the fifth to eighth terminals of the encoding module 3312 are connected to a DP pin, a DN pin, a CC1 pin, and a CC2 pin, respectively, the third terminal of the demagnetization detecting module 3318 is connected to the ninth terminal of the encoding module 3312 via the confirmation module 3320, the first terminal of the regulator 3306 is connected to a VDD pin, the second terminal of the regulator 3306 is connected to the first terminal of the UVLO module 3308, the second terminal of the UVLO module 3308 outputs a PG signal, the third terminal of the UVLO module 3308 outputs an AVDD signal, the first terminal of the comparator 3322 receives a Vdrain voltage (voltage at the drain of the synchronous rectification switch tube Q2), the second terminal is grounded, the first terminal of the comparator 3324 receives the Vdrain voltage, the second terminal is grounded, the third terminal of the comparator 3322 is connected to the reset terminal of the RS flip-flop 3328 via the minimum on time control module 3326, the third terminal of the comparator 3324 is connected to the set terminal of the RS flip-flop 3328, an output terminal of the RS flip-flop 3328 may be connected to a first terminal of the logic control module 3330, a second terminal of the logic control module 3330 may be connected to a fourth terminal of the synchronous rectification control module 3302, a third terminal of the logic control module 3330 may be connected to a first terminal of the gate driving module 3332, a second terminal of the gate driving module 3332 is connected to a first terminal of the synchronous rectification module 3302, and a third terminal of the gate driving module 3332 is connected to a sixth terminal of the synchronous rectification module 3302.

As an example, the synchronous rectification control module 3302 may be configured to generate the second control signal for controlling the on and off of the synchronous rectification switch tube Q2 based on the drain voltage of the synchronous rectification switch tube Q2 after the power switch tube Q1 is turned off.

Specifically, after the power switch Q1 is turned off, the secondary winding starts to demagnetize, in order to prevent the primary and secondary windings from being in common, the body diode (body diode) of the synchronous rectification switch Q2 is firstly turned on, and the comparator 3322 may be configured to compare the Vdrain voltage with a preset threshold, and when the Vdrain voltage is less than the preset threshold (e.g., -300mV), cause the gate driving module 3332 to generate a second control signal for controlling the conduction of the synchronous rectification switch Q2; as the demagnetization current gradually decreases, the Vdrain voltage gradually rises, and the comparator 3324 may be configured to compare the Vdrain voltage with a preset threshold, and when the Vdrain voltage is greater than the preset threshold (e.g., -3.5mV or 0mV), cause the gate driving module 3332 to generate a second control signal for controlling the turn-off of the synchronous rectification switch Q2.

As an example, in order to prevent the demagnetization starting resonance from affecting the detection of the Vdrain voltage, which may cause the synchronous rectification switch Q2 to be turned off by mistake in advance, the minimum on-time setting module 3326 may be used to set the minimum on-time of the synchronous rectification switch Q2, so as to prevent the synchronous rectification switch Q2 from being turned off by mistake in advance.

As an example, the demagnetization detection module 3318 may be configured to perform demagnetization detection when performing encoding control.

As an example, after the primary feedback control chip receives and decodes the encoded information from the secondary synchronous rectification and protocol control chip, the primary feedback control chip may perform authenticity check on the request information according to the preset information, and notify the secondary synchronous rectification and protocol control chip that the primary feedback control chip receives the correct request information after the check result is correct, thereby implementing data communication information interaction on the charger side.

As an example, the confirmation module 3320 may be configured to receive the confirmation information from the primary side feedback control chip after the request information is verified, if the request message is not verified, no acknowledgement message is received from the primary feedback control chip, if the confirmation information from the primary side feedback control chip is not received in the preset time after the secondary side synchronous rectification and protocol control chip sends the coding information, the secondary synchronous rectification and protocol control chip will continue to send a primary coded message to the primary feedback control chip, if after a number of attempts (e.g., three) no acknowledgement information is still received from the primary side feedback control chip, it may be determined that the charger is a normal charger such that the switching power supply provides a default signal to the device to be charged, e.g., the output voltage defaults to 5V.

As an example, the encoding module 3312 may be configured to receive the request information from the device to be charged through the data signal lines DP, DN and CC1, CC2, identify the request information based on a predetermined encoding rule, obtain encoded information, output a second control signal for controlling the on and off of the synchronous rectification switch tube Q2 through the synchronous rectification control logic and driving module, and couple and transmit the second control signal to the primary feedback control chip through the transformer for decoding.

Specifically, the encoding module 3312 may be configured to encode the request information by delaying turning off of the synchronous rectification switch tube Q2 when the request information is output by the device to be charged, and normally turning off of the synchronous rectification switch tube Q2 when the request information is not output by the device to be charged (as shown in fig. 8), resulting in encoded information.

As an example, the dummy load module 3314 may be configured to prevent overshoot on the output voltage by adding a dummy load to the secondary side synchronous rectification and protocol control chip when the switching power supply is in a dynamic state; when a plug is unplugged or the switching power supply is in a no-load state, the output voltage or the output current needs to be adjusted, the working frequency of the system is too low, and the coding time is longer, the frequency is improved by adding a dummy load of a secondary synchronous rectification and protocol control chip (namely, the dummy load of the switching power supply is added), and the coding time is reduced.

As one example, the regulator 3304, the regulator 3306, the UVLO module 3308, and the system output detection module 3310 may be configured to power various components in the secondary synchronous rectification and protocol control chip 330.

It should be noted that, the synchronous rectification switch tube Q2 may be located inside the secondary synchronous rectification and protocol control chip as shown in the figure, and the synchronous rectification switch tube Q2 may also be packaged independently, which is not limited in this embodiment of the present invention.

As shown in fig. 7, in the switching power supply provided in the embodiment of the present invention, the secondary synchronous rectification and protocol control chip 330 receives request information from a device to be charged via signal lines DP, DN or CC1, CC2, where the request information is used to indicate an output voltage, an output current request, or a protection request, the encoding circuit 3312 may be configured to perform encoding modulation on the request information, and apply the modulation result to a control signal of the synchronous rectification switch tube Q2 through logic control to control the secondary synchronous rectification and protocol control chip to output a Vdrain signal, the Vdrain signal is represented by different characteristics of a voltage on the secondary winding and a current detection signal on the primary side, the primary side feedback control chip 320 may utilize the current detection module 3214 and the decoding module 3216 to decode the encoded information, identify the obtained pre-made request information, perform output voltage adjustment according to the information, and perform protection on the output voltage, Output current regulation or protection, etc.

For better understanding of the principle of the coding logic of the coding module provided by the embodiment of the present invention, the coding logic is introduced below by way of specific examples. Referring to fig. 8, fig. 8 is a schematic diagram illustrating waveforms of a coding duty cycle and a normal duty cycle provided by an embodiment of the present invention.

Wherein, the waveform SR gate represents the control signal of the secondary synchronous rectification and protocol control chip 330 for controlling the on/off of the synchronous rectification switch tube Q2, the waveform SR Vdrain represents the voltage at the drain of the synchronous rectification switch tube Q2 in the secondary synchronous rectification and protocol control chip 330, the waveform SR Isk represents the secondary current, the waveform PSR gate represents the control signal of the primary feedback control chip 320 for controlling the on/off of the power switch tube Q1, the waveform PSR FB represents the output feedback signal for representing the output voltage, tdemeg corresponds to the demagnetization time, and Tring corresponds to the resonance time.

As shown, the difference between the encoding duty cycle (corresponding to the time period t0 to t9, labeled 1) and the normal duty cycle (corresponding to the time period t9 to t13, labeled 0) is mainly: during the encoding duty cycle, the synchronous rectifier switch Q2 is turned off with a delay (for example, 2us) for a certain time (refer to fig. 8, and during a time period t2 to t3, the dashed portion of the SR gate waveform) during the delay time period, the secondary side current Isk will continue to increase negatively to Isk1 after dropping to zero, at this time, the output voltage of the converter reversely excites the secondary side winding Nsec to store energy, the voltage on the auxiliary winding Naux continues to clamp at Vaux (V0 Naux)/Nsec, the voltage on the auxiliary winding Naux maintains a voltage plateau at the FB pin after the voltage on the auxiliary winding Naux is divided by the voltage dividing resistors R1 and R2, and refer to the PSR FB waveform in fig. 8. After the synchronous rectification switch tube Q2 is turned off, the reverse excitation energy at the secondary side is transferred to the primary side, for example, the reverse excitation energy may be transferred to the primary side through the current detection resistor Rs, the parasitic capacitor of the power switch tube Q1, the primary winding Npri and the input capacitor Cbulk, the primary winding Npri is reversely demagnetized, which results in energy backflow, and after demagnetization is completed, the feedback energy charges the junction capacitor (labeled Coss) of the power switch tube Q1 again, so that the drain-source voltage of the power switch tube Q1 is clamped at Vbulk + N Vo. When the flyback switching power supply works in a Quasi-Resonant (QR) mode and the primary side current Ipk is gradually increased to 0, the output feedback signal PSR FB oscillates to the valley bottom, the original Resonant period can be maintained to continue working under light load, and the primary side power switching tube Q1 can be switched on by Zero Voltage (ZVS) under heavy load.

As can be seen from fig. 8, during the coding duty cycle, due to the delayed turn-off of the synchronous rectification switching tube Q2, the falling rate of the falling edge Tf1 of the waveform of the output feedback signal FB at the primary side of the coding duty cycle Is significantly increased compared to the falling rate of the falling edge Tf2 of the waveform of the output feedback signal FB at the normal duty cycle, and the negative voltage of the voltage signal Vcs (Vcs Is Ipk Rsense, Rsense Is a detection resistor, Ipk Is the primary side current, i.e., Is in fig. 6) representing the primary side current Ipk at the coding duty cycle Is significantly different from the negative voltage of the voltage signal Vcs representing the primary side current Ipk at the normal duty cycle.

Therefore, the falling edge of the waveform of the output feedback signal FB and the negative voltage of the voltage signal Vcs representing the primary current can be used as decoding conditions to form a coding working period. During the encoding working period, after demagnetization is finished, when the falling time of the falling edge Tf1 of the waveform of the output feedback signal FB of the encoding working period is less than a certain threshold (e.g., 200ns), and the negative-going signal of the primary side voltage Vcs representing the primary side current is less than a certain threshold (e.g., -200mV) and is maintained for a certain time (e.g., 150ns), it can be determined that there is the request information from the device to be charged and the encoded information needs to be decoded. That is, the decoding module 3216 may begin to prepare to decode and identify the encoded information in subsequent cycles.

In addition, to avoid false detection, the whole encoding can be set to be a multi-bit flag bit to prepare for the decoding work of the decoding module at the primary side, for example, encoding to be a combination of multiple encoding duty cycles 1 and normal duty cycle 0, and setting an end flag bit after the encoding is finished.

As an example, according to the request information, codes corresponding to different voltages, different currents, and protection request information may be set, for example, when the device to be charged requests to output a voltage of 9V, the code may be set to 11010111, as shown in fig. 9, where fig. 9 shows a corresponding code provided by an embodiment of the present invention when the device to be charged requests to output a voltage of 9V. Specifically, the device to be charged requests to output a 9V voltage, so that the code consists of 8 cycles, the first two cycles may be 11 flag bits, the next four cycles may be 0101, which represents that the request information from the device to be charged requires that the output voltage be raised to 9V or lowered to 9V, the last two cycles may be end flag bits 11, and after the end of the end flag bits, the FB pin of the primary side feedback control chip may switch the reference voltage received by the constant voltage control module to Vref _9V, so as to output the 9V voltage to the device to be charged.

As an example, the code 11010111 corresponding to the output 9V voltage may be used to set the output voltage as described above, and may also be used to directly set the output current according to a preset rule, for example, the code 11010111 may be used to represent 9V/2A, and after receiving the coded information, the decoding module in the primary feedback control chip may first perform an output voltage request and then perform an output current request, so that the constant current control module may switch Vref _ cc to 2A gear to output 2A current to the device to be charged.

As an example, the output current may also be set separately, for example, a code 11000111 may be used to represent the output current at a voltage of 9V, as shown in fig. 10, where fig. 10 shows a corresponding code provided by an embodiment of the present invention when a device to be charged requests to output a voltage/current of 9V/2A. After receiving the coded information, a decoding module in the primary side feedback control chip decodes the coded information, so that a constant current control module in the primary side feedback control chip can switch a current gear Vref _ cc under the current voltage into a 2A gear, and output 2A current to the equipment to be charged.

As an example, the protection request information may also be transmitted by encoding, for example, when a Universal Serial Bus (USB) data line is pulled out, the charger still operates in a voltage state higher than a voltage state such as 5V, and at this time, if other devices to be charged which do not support fast charging are directly plugged in, the devices to be charged may be damaged, so once the USB data line is pulled out, the output voltage of the switching power supply should be quickly returned to a safe voltage state such as 5V. As shown in fig. 11, fig. 11 shows a code corresponding to a current device to be charged when being pulled out, where the code 11010011 may be used to indicate that a USB data line needs to be protected when being pulled out, and after a decoding module in a primary side feedback control chip receives and decodes encoded information, an FB pin of the primary side feedback control chip may switch a reference voltage of a constant voltage control module in the primary side feedback control chip to Vref _5V to provide a 5V output voltage for the device to be charged. It can be seen that the code corresponding to the protection request information may not be consistent with the code corresponding to the output voltage 5V, that is, a plug-unplugging code may be specifically set.

As described above, in order to prevent the encoding time from being long during the idle time, after the request information is received through the data lines DP and DN or CC1 and CC2, a certain dummy load may be added to the output side of the secondary side synchronous rectification and protocol control chip, which is equivalent to increasing the load of the switching power supply to increase the switching frequency and reduce the encoding time.

The number of bits of the code length provided in the embodiment of the present invention is not limited, and the number of bits of the code may be set to 8 as described above, however, when the request information from the device to be charged is less, the number of bits of the code may also be reduced, and when the request information from the device to be charged is more, the number of bits of the code may be increased, and a specific logic principle of the code may be as shown in fig. 8.

As an example, fig. 12 shows a graph of waveforms involved in a primary-secondary communication response mechanism implemented between a check module of a primary feedback control chip and a confirmation module of a secondary synchronous rectification and protocol control chip according to an embodiment of the present invention.

As described above, after the secondary synchronous rectification and protocol control chip sends the encoded information, it is desirable to receive the response information from the primary feedback control chip, so as to implement data communication interactivity between the primary and secondary.

Specifically, after the primary side feedback control chip receives the coding information from the secondary side synchronous rectification and protocol control chip, within a preset time (for example, 5us), the primary side feedback control chip performs authenticity verification on the request information obtained by decoding, provides a verification result, and controls the gate drive module to output a high-frequency signal with 4 to 5 continuous periods under the condition that the request information passes the authenticity verification, for example, the on-time may be 400ns, the high-frequency period may be 250kHz (the normal operating frequency is about 100kHz, the high-frequency may be set to be higher than the normal operating frequency and a certain margin is left), so as to notify the secondary side synchronous rectification and protocol control chip that the secondary side synchronous rectification and protocol control chip receives the correct request information, and at this time, the Vcs signal maintains the minimum value of Vcsmin, so as to prevent the energy from being too much; the secondary side synchronous rectification and protocol control chip detects and judges the preset frequency through the Vdrain pin within the preset time, for example, within 5us after sending the coded information, for example, if the detected frequency is higher than, for example, 150kHz (the frequency can be set to be higher than the normal operating frequency of the system and lower than the high-frequency sent by the primary side chip), continuously for 4 to 5 cycles, it can be determined that the primary side feedback control chip receives the correct request information, if the preset frequency information is not detected within the preset time after sending the coded information, it can be determined that the primary side feedback control chip does not receive the correct request information, in this case, the secondary side synchronous rectification and protocol control chip can resend the coded information once, the repetition number can be changed depending on the specific application, as an example, the sending number can be set to 3 times, if the confirmation information from the primary side feedback control chip is not received after the coded information is transmitted for the preset number of times, it can be determined that the charger is a normal charger, and a default voltage, for example, 5V, is output.

In summary, the switching power supply provided by the embodiment of the invention can save expensive isolation devices such as optocouplers and capacitors, and in addition, the embodiment of the invention can transmit various information, thereby improving the diversity of information transmission. Based on the existing switching power supply circuit without a communication element such as an optocoupler and the like, the communication mode between the primary side and the secondary side provided by the invention can carry more information (for example, a plurality of bits) according to practical application.

In the foregoing embodiments, the embodiments of the present invention provide a primary side feedback isolated switching power supply and a data communication method for performing an authenticity check response between a primary side and a secondary side, where energy may be fed back from the secondary side to the primary side by delaying turning off a synchronous rectification switching tube of the secondary side, and then a communication relationship is established by using a difference between a negative current flowing through a primary winding detected by a current detection module of the primary side and a falling edge of an output feedback signal detected by a demagnetization detection module, so as to prove that there is request information from a device to be charged, a decoding module of the primary side may be used to decode encoded information from the secondary side, and in order to ensure that the primary side receives correct request information, the primary side performs an authenticity check on the decoded request information according to preset information after decoding the encoded information, and sends response information to the secondary side after passing the check, and informing the primary side of receiving the correct request information to the secondary side through the response information so as to establish a communication relation between the primary side and the secondary side.

The scheme provides a method for realizing communication between the original secondary side without an additional isolation device, and specifically, a secondary side synchronous rectification and protocol control chip of a switching power supply encodes request information from equipment to be charged to obtain a binary code, a current detection module and a demagnetization detection module of a primary side feedback control chip recognize the code and decode the binary code, and simultaneously the primary side judges the authenticity of the decoded request information according to preset information, if the authenticity of the decoded request information is judged, response information is provided for the secondary side, and the switching power supply is controlled to provide output information for the equipment to be charged based on the decoded request information. In the field where the device to be charged needs to be charged quickly, when the device to be charged requests a new voltage, current or malfunction, the technical scheme provided by the embodiment of the invention cancels the traditional isolating devices such as optocouplers, capacitors and the like, the output voltage, the output current, the protection request information and the like can be coded through preset coding rules to obtain binary codes, the primary side feedback control chip can detect the primary side current through the built-in current detection module and detect the demagnetization condition of the primary side winding through the built-in demagnetization detection module, and based on the negative current and demagnetization conditions, decoding the binary code by using a built-in decoding module to acquire the request information, and the authenticity of the request information is verified to provide response information for the secondary side, and the switching-on and switching-off of the primary side power switching tube are controlled in response to the output requirement and the control signal. The switching power supply provided by the embodiment of the invention has the advantages that the cost is reduced, the circuit structure is simplified, the response speed is improved, the correctness of the request information is ensured through the authenticity verification, and a safe and reliable communication method is provided between the original secondary side.

In addition, referring to fig. 13, an embodiment of the present invention further provides a method 1300 for use in the above-described switching power supply, configured to charge a device to be charged, where the switching power supply includes a secondary side synchronous rectification and protocol control chip and a primary side feedback control chip, and the method 1300 includes the following steps: s1310, encoding request information from the equipment to be charged by using a secondary side synchronous rectification and protocol control chip to obtain encoded information; and S1320, decoding the coded information by using the primary side feedback control chip to obtain request information, performing authenticity verification on the request information, sending confirmation information to the secondary side synchronous rectification and protocol control chip under the condition that the request information passes the authenticity verification, and controlling the switching power supply to provide an output signal for the equipment to be charged based on the request information.

As an example, the method may further comprise: and under the condition that the request information does not pass the authenticity verification, the primary side feedback control chip does not send confirmation information to the secondary side synchronous rectification and protocol control chip.

As an example, the method may further comprise: and under the condition that the confirmation information is not received in a preset time period after the secondary side synchronous rectification and protocol control chip sends the coding information, the secondary side synchronous rectification and protocol control chip is utilized to continuously send the coding information to the primary side feedback control chip, and under the condition that the confirmation information is not received even if the frequency of sending the coding information exceeds the preset frequency, the primary side feedback control chip is utilized to control the switching power supply to provide a preset output signal for the equipment to be charged.

As an example, the switching power supply further includes a transformer, the primary side feedback control chip includes a first power switch tube, and the method further includes: when the first power switch tube is in a turn-off state, detecting the demagnetization condition of a primary winding of the transformer based on an output feedback signal representing the output voltage of the switch power supply; generating a first current detection signal when detecting a negative current flowing through a primary winding; decoding the coded information based on the demagnetization condition and the first current detection signal to obtain request information; controlling the switching power supply to supply a constant voltage to the device to be charged based on the voltage request information in the request information; and controlling the switching power supply to supply a constant current to the device to be charged based on the current request information in the request information.

As an example, the method further comprises: generating a second current detection signal when detecting a forward current flowing through the primary winding; controlling the switching power supply to provide a constant voltage for the equipment to be charged based on the demagnetization condition and the second current detection signal; and controlling the switching power supply to supply a constant current to the device to be charged based on the demagnetization condition and the second current detection signal.

As an example, the method further comprises: sampling the platform voltage of the output feedback signal during the demagnetization time of the primary winding to obtain a sampling voltage; and generating a first control signal for controlling the on and off of the first power switch tube based on the sampling voltage and the voltage signal representing the primary side current.

As an example, detecting demagnetization of a primary winding of a transformer based on an output feedback signal includes: and taking the time period from the time when the output feedback signal rises to be more than a third preset threshold value to the time when the output feedback signal falls to be less than the third preset threshold value as the demagnetization time of the primary winding.

As an example, decoding the encoded information based on the demagnetization and the first current detection signal to obtain the request information includes: and when the falling time of the falling edge of the output feedback signal is smaller than a fourth preset threshold and the first current detection signal is smaller than a fifth preset threshold, decoding the coded information to obtain the request information.

As an example, the secondary side synchronous rectification and protocol control chip includes a second power switch tube, and the method further includes: after the first power switch tube is turned off, generating a second control signal for controlling the on and off of the second power switch tube based on the drain voltage of the second power switch tube; and coding the request information to obtain coded information by delaying the turn-off of the second power switch tube when the equipment to be charged outputs the request information and normally turning off the second power switch tube when the equipment to be charged does not output the request information.

As an example, generating a second control signal for controlling on and off of a second power switch tube based on a drain voltage of the second power switch tube includes: when the drain voltage of the second power switch tube is smaller than a sixth preset threshold value, controlling the second power switch tube to be in a conducting state; and when the drain voltage of the second power switch tube is greater than a seventh preset threshold, controlling the second power switch tube to be in a turn-off state, wherein the sixth preset threshold is smaller than the seventh preset threshold.

As an example, the method further comprises: when the inductance of the primary winding and the junction capacitance of the first power switching tube resonate, the minimum conduction time of the second power switching tube is set so as to prevent the second power switching tube from being turned off by mistake in advance.

As an example, the method further comprises: when the switching power supply is in a dynamic state or an idle state and the device to be charged is pulled out, the load of the switching power supply is increased so as to reduce the time for coding the request information.

As an example, the method further comprises: and controlling overvoltage, undervoltage, open circuit and short circuit protection of the output voltage provided by the switching power supply to the equipment to be charged based on the protection request information in the request information.

It is understood that, when the switching power supply is introduced above, technical details thereof have been described in detail, and therefore, for simplicity of description, some details of the method embodiment may be referred to the above description of the switching power supply embodiment, and are not described herein again.

It is to be understood that the invention is not limited to the precise arrangements and instrumentalities shown. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present invention are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications and additions or change the order between the steps after comprehending the spirit of the present invention.

The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.

It should also be noted that the exemplary embodiments mentioned in this patent describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed simultaneously.

As described above, only the specific embodiments of the present invention are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A switching power supply is used for charging a device to be charged, and is characterized by comprising:

the secondary side synchronous rectification and protocol control chip is configured to obtain coding information by coding request information from the equipment to be charged; and

And the primary side feedback control chip is configured to decode the coded information to obtain the request information, perform authenticity verification on the request information, send confirmation information to the secondary side synchronous rectification and protocol control chip when the request information passes the authenticity verification, and control the switching power supply to provide an output signal for the equipment to be charged based on the request information.

2. The switching power supply according to claim 1,

the primary side feedback control chip is further configured not to send the confirmation information to the secondary side synchronous rectification and protocol control chip if the request information fails the authenticity check.

3. The switching power supply according to claim 1,

the primary side feedback control chip is further configured to generate a plurality of signals with higher than a preset frequency within a preset time under the condition that the request information passes the authenticity verification, so as to inform the secondary side synchronous rectification and protocol control chip that the primary side feedback control chip receives correct request information, wherein the confirmation information can be characterized as the plurality of signals with higher than the preset frequency.

4. The switching power supply according to claim 1,

the secondary side synchronous rectification and protocol control chip is further configured to continue to send the coded information to the primary side feedback control chip under the condition that the confirmation information is not received within a preset time period after the coded information is sent, and control the switching power supply to provide a preset output signal to the equipment to be charged by using the primary side feedback control chip under the condition that the confirmation information is not received even if the number of times of sending the coded information exceeds a preset number of times.

5. The switching power supply of claim 1, further comprising a transformer, wherein the primary side feedback control chip comprises a first power switching tube, and wherein the primary side feedback control chip is further configured to:

when the first power switch tube is in a turn-off state, detecting the demagnetization condition of a primary winding of the transformer based on an output feedback signal representing the output voltage of the switch power supply;

generating a first current detection signal when detecting a negative current flowing through the primary winding;

decoding the coding information based on the demagnetization condition and the first current detection signal to obtain the request information;

Controlling the switching power supply to supply a constant voltage to the device to be charged based on voltage request information in the request information; and

controlling the switching power supply to supply a constant current to the device to be charged based on current request information in the request information.

6. The switching power supply of claim 5, wherein the primary side feedback control chip is further configured to:

generating a second current detection signal when detecting a forward current flowing through the primary winding;

controlling the switching power supply to provide a constant voltage to the device to be charged based on the demagnetization condition and the second current detection signal; and

and controlling the switching power supply to provide constant current for the equipment to be charged based on the demagnetization condition and the second current detection signal.

7. The switching power supply of claim 5 or 6, wherein the primary side feedback control chip is further configured to:

sampling the platform voltage of the output feedback signal during the demagnetization time of the primary winding to obtain a sampling voltage; and

and generating a first control signal for controlling the on and off of the first power switch tube based on the sampling voltage and a voltage signal representing the current flowing through the primary winding.

8. The switching power supply of claim 5, wherein the primary side feedback control chip is further configured to:

and taking the time period from the time when the output feedback signal rises to be greater than a third preset threshold value to the time when the output feedback signal falls to be less than the third preset threshold value as the demagnetization time of the primary winding.

9. The switching power supply of claim 5, wherein the primary side feedback control chip is further configured to:

and when the falling time of the falling edge of the output feedback signal is smaller than a fourth preset threshold and the first current detection signal is smaller than a fifth preset threshold, decoding the coded information to obtain the request information.

10. The switching power supply of claim 5, wherein the secondary side synchronous rectification and protocol control chip comprises a second power switching tube, and wherein the secondary side synchronous rectification and protocol control chip is further configured to:

after the first power switch tube is turned off, generating a second control signal for controlling the second power switch tube to be turned on and off based on the drain voltage of the second power switch tube; and

and coding the request information by performing delayed turn-off on the second power switch tube when the equipment to be charged outputs the request information and performing normal turn-off on the second power switch tube when the equipment to be charged does not output the request information, so as to obtain the coded information.

11. The switching power supply of claim 10, wherein the secondary side synchronous rectification and protocol control chip is further configured to:

when the drain voltage of the second power switch tube is smaller than a sixth preset threshold value, controlling the second power switch tube to be in a conducting state; and

and when the drain voltage of the second power switch tube is greater than a seventh preset threshold, controlling the second power switch tube to be in a turn-off state, wherein the sixth preset threshold is smaller than the seventh preset threshold.

12. The switching power supply of claim 10, wherein the secondary side synchronous rectification and protocol control chip is further configured to:

and when the inductance of the primary winding and the junction capacitance of the first power switch tube resonate, setting the minimum on-time of the second power switch tube to prevent the second power switch tube from being turned off by mistake in advance.

13. The switching power supply of claim 1, wherein the secondary side synchronous rectification and protocol control chip is further configured to:

and when the switching power supply is in a dynamic state or a no-load state and the equipment to be charged is pulled out, increasing the load of the switching power supply so as to reduce the time for coding the request information.

14. The switching power supply of claim 1, wherein the primary side feedback control chip is further configured to:

and controlling overvoltage, undervoltage, open-circuit and short-circuit protection of the output voltage provided by the switching power supply to the equipment to be charged based on the protection request information in the request information.

15. A method in a switching power supply for charging a device to be charged, the switching power supply comprising a secondary synchronous rectification and protocol control chip and a primary feedback control chip, the method comprising:

encoding the request information from the equipment to be charged by utilizing the secondary side synchronous rectification and protocol control chip to obtain encoded information; and

the primary side feedback control chip is used for decoding the coded information to obtain the request information, the request information is subjected to authenticity verification, confirmation information is sent to the secondary side synchronous rectification and protocol control chip under the condition that the request information passes the authenticity verification, and the switching power supply is controlled to provide an output signal for the equipment to be charged based on the request information.

16. The method of claim 15, further comprising:

And under the condition that the request information does not pass the authenticity verification, the primary side feedback control chip does not send the confirmation information to the secondary side synchronous rectification and protocol control chip.

17. The method of claim 15, further comprising:

and under the condition that the request information passes the authenticity verification, the primary side feedback control chip generates a plurality of signals with the frequency higher than the preset frequency within the preset time so as to inform the secondary side synchronous rectification and protocol control chip that the primary side feedback control chip receives correct request information, wherein the confirmation information can be represented as the plurality of signals with the frequency higher than the preset frequency.

18. The method of claim 15, further comprising:

and under the condition that the confirmation information is not received within a preset time period after the secondary synchronous rectification and protocol control chip sends the coding information, the secondary synchronous rectification and protocol control chip is utilized to continuously send the coding information to the primary feedback control chip, and under the condition that the confirmation information is not received even if the number of times of sending the coding information exceeds the preset number of times, the primary feedback control chip is utilized to control the switching power supply to provide a preset output signal for the equipment to be charged.

19. The method of claim 15, the switching power supply further comprising a transformer, wherein the primary side feedback control chip comprises a first power switch tube, the method further comprising:

20. The method of claim 19, further comprising:

21. The method according to claim 19 or 20, further comprising:

22. The method of claim 19, wherein said detecting a demagnetization condition of the primary winding of the transformer based on the output feedback signal comprises:

23. The method of claim 19, wherein said decoding said encoded information based on said demagnetization event and said first current detection signal to obtain said requested information comprises:

24. The method of claim 19, wherein the secondary side synchronous rectification and protocol control chip comprises a second power switch tube, the method further comprising:

25. The method of claim 24, wherein generating a second control signal for controlling the second power switch to turn on and off based on the drain voltage of the second power switch comprises:

and when the drain voltage of the second power switch tube is greater than a seventh preset threshold value, controlling the second power switch tube to be in a turn-off state, wherein the sixth preset threshold value is smaller than the seventh preset threshold value.

26. The method of claim 24, further comprising:

and when the inductance of the primary winding and the junction capacitance of the first power switching tube resonate, setting the minimum on-time of the second power switching tube to prevent the second power switching tube from being turned off by mistake in advance.

27. The method of claim 15, further comprising:

and when the switching power supply is in a dynamic state or a no-load state and the device to be charged is pulled out, increasing the load of the switching power supply so as to reduce the time for coding the request information.

28. The method of claim 15, further comprising:

and controlling overvoltage, undervoltage, open circuit and short circuit protection of the output voltage provided by the switching power supply to the equipment to be charged based on protection request information in the request information.