Error amplifier circuit and applicable switching power supply and method

Abstract

The present application provides an error amplifier circuit and a switching power supply and method applicable thereto; wherein the error amplifier circuit comprises: an error amplifier unit, whose positive input terminal obtains an integrated signal, whose negative input terminal obtains one of a reference signal and a feedback signal, and whose output terminal generates an error amplification signal; a compensation unit receives the other of the reference signal and the feedback signal and is connected to the positive input terminal of the error amplifier unit, and is used to compensate the feedback error amplification signal and integrate it with the signal obtained at the first input terminal to obtain an integrated signal; wherein the integrated signal is used to compensate the error amplifier unit to weaken the power supply with deviation outputted by the switching power supply to the load side based on the change of the external circuit. The present application realizes that the voltage deviation between the feedback signal and the reference signal is independent of the stable interval of the error amplification signal.

Description

Technical Field

[0001] The present application relates to the technical field of drive circuits, and in particular to an error amplifier circuit and a switching power supply and method applicable thereto. Background Art

[0002] A switching power supply is a device used to convert electric energy, converting the AC power provided by the power grid into a DC output. It is widely used to provide driving power for electronic devices that require DC power due to its advantages such as high integration, low cost, strong product adaptability, and low standby power consumption. Taking a mobile phone charger as an example, a switching power supply converts AC power into a DC power supply for charging a mobile phone, and transmits it to the mobile phone via a data cable, thereby charging the mobile phone.

[0003] However, taking terminal electronic products as an example, users will use the universal data cable on the charger to charge different types of mobile phones. This makes the connection of different loads make it impossible for the switching power supply in the charger to provide constant voltage power supply. Summary of the invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present application is to provide an error amplifier circuit and a switching power supply and method applicable thereto, so as to solve the problem in the prior art that the switching on-off mode based on the signal output by the error amplifier circuit for timing in the switching power supply is not conducive to providing stable power supply for the load.

[0005] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application provides an error amplifier circuit, which is applied to a switch control device, including: an error amplifier unit, having a positive input terminal, a negative input terminal and an output terminal; wherein the positive input terminal obtains an integrated signal, and the negative input terminal obtains one of a reference signal and a feedback signal from the first input terminal of the error amplifier circuit; wherein the feedback signal is used to reflect the load power provided to the load side by the switching power supply where the switch control device is located; wherein the error amplifier unit is used to amplify the error between the two signals received by the positive input terminal and the negative input terminal based on a preset gain and output an error amplified signal; a compensation unit, which receives the other of the reference signal and the feedback signal from the second input terminal of the error amplifier circuit and is connected to the positive input terminal of the error amplifier unit, and is used to compensate the feedback error amplified signal and integrate it with the signal obtained from the first input terminal to obtain the integrated signal; wherein the integrated signal is used to compensate the error amplifier unit to weaken the power supply with deviation output by the switching power supply to the load side based on the change of the external circuit.

[0006] In certain embodiments of the first aspect of the present application, the compensation unit includes: a gain compensation module, connected to the output end of the error amplification unit, and used to convert the error amplification signal fed back from the output end into a compensation signal based on the gain; a signal integration module, connected to the second input end of the error amplification circuit, the positive input end of the error amplification unit, and the gain compensation module, and used to integrate the compensation signal with the reference signal or feedback signal obtained from the second input end so as to reduce the deviation of the error amplification unit and obtain the integrated signal.

[0007] In certain embodiments of the first aspect of the present application, the gain compensation module includes: a feedback compensation circuit, which is arranged on the line between the output end of the error amplification unit and the signal integration module based on the gain, and is used to divide the feedback error amplification signal based on the gain and output the compensation signal.

[0008] In certain embodiments of the first aspect of the present application, the gain compensation module also includes: a buffer circuit, arranged on the feedback compensation circuit, for buffering the error amplification signal fed back within at least one switching cycle, so that the feedback compensation circuit outputs a compensation signal for reflecting the mean value of the error amplification signal.

[0009] In certain embodiments of the first aspect of the present application, the signal integration module includes: an addition integration circuit, connected between the second input terminal and the positive input terminal of the error amplification unit, for adding the acquired reference signal and the compensation signal to obtain an integrated signal; or a subtraction integration circuit, connected between the second input terminal and the positive input terminal of the error amplification unit, for subtracting the compensation signal from the acquired feedback signal to obtain an integrated signal.

[0010] In certain embodiments of the first aspect of the present application, the error amplification unit includes: an error amplifier, which outputs the error amplified signal based on the error signal between the two signals provided by the positive input terminal and the negative input terminal; and a gain amplification module, connected between the negative input terminal and the output terminal of the error amplifier, for determining the gain.

[0011] According to a second aspect of the present application, there is provided a switch control device, which changes an electrical signal in a power conversion unit connected to a power supply bus so that the power conversion unit provides stable power supply to a load, and comprises: a load feedback unit, coupled to the power conversion unit, for generating and outputting a feedback signal for reflecting a power supply signal on the load side; a switch unit, arranged on the power supply bus and connected to the power conversion unit; a conduction detection unit, connected to the error amplifier circuit, comprising an error amplifier circuit as described in any one of the first aspects; wherein the first input terminal and the second input terminal of the error amplifier circuit receive a reference signal and the feedback signal respectively; the conduction detection unit performs conduction detection based on the error amplification signal, and outputs a first conduction detection signal according to the detection result; a disconnection detection unit, which samples an induction signal in the power conversion unit, detects the sampled signal and outputs a disconnection detection signal based on the detection result; and a logic control unit, connected to the conduction detection unit and the disconnection detection unit, for controlling the switch unit to be turned on / off based on the control logic of the disconnection detection signal and the first conduction detection signal.

[0012] In certain embodiments of the second aspect of the present application, the load feedback unit includes: an inductance sensor coupled to the inductance in the power conversion unit for generating an induction signal for outputting power to the load side; a voltage divider circuit arranged on a line between the inductance sensor and a reference voltage terminal, for outputting the feedback signal based on the electrical signal output by the inductance sensor.

[0013] In certain embodiments of the second aspect of the present application, the conduction detection unit also detects the induction signal of the power conversion unit and outputs a second conduction detection signal based on the detection result; the logic control unit controls the on / off of the switch unit based on the control logic of the disconnection detection signal, the first conduction detection signal, and the second conduction detection signal.

[0014] The third aspect of the present application provides a switching power supply, comprising: a rectifier unit connected to an external AC power supply, used to rectify the connected AC power and output it to a power supply bus; a switch unit connected to the power supply bus and controlled to be turned on / off; a power conversion unit connected to the switch unit, used to provide stable power supply to a load by means of an intermittent electrical signal generated by the switch unit, wherein the power conversion unit includes an energy storage circuit, and an inductive circuit used to convert the intermittent electrical signal into a power supply for both load power supply and energy storage of the energy storage circuit; a switch control device as described in any one of the second aspects.

[0015] In certain embodiments of the third aspect of the present application, the inductor circuit includes: a primary winding, connected to the power supply bus and the switch control device; a secondary winding, coupled to the primary winding, connected to the power supply bus and providing a power supply terminal on the load side; and the energy storage circuit is connected between the power supply bus and the power supply terminal.

[0016] In certain embodiments of the third aspect of the present application, the load feedback unit in the switch control device is coupled to the primary winding or the secondary winding.

[0017] In certain embodiments of the third aspect of the present application, the inductance circuit includes: an inductor connected to the power supply bus and the switch control device; and the energy storage circuit connected between the current output end of the inductor and the power supply bus.

[0018] In certain embodiments of the third aspect of the present application, the load feedback unit in the switch control device is coupled to the inductor or to a load output terminal on the load side of the power conversion unit.

[0019] The fourth aspect of the present application provides a method for generating an error amplification signal, comprising: obtaining a reference signal and a feedback signal; wherein the feedback signal is used to reflect the load power provided by the switching power supply where the switching control device is located to the load side; based on a preset gain, amplifying the error between an integrated signal and one of the reference signal and the feedback signal, and outputting an error amplification signal; wherein the integrated signal is obtained by integrating the compensated error amplification signal with the other of the reference signal and the feedback signal; wherein the integrated signal is used to compensate the error amplification signal to weaken the power supply with deviation output by the switching power supply to the load side based on changes in the external circuit.

[0020] In certain embodiments of the fourth aspect of the present application, the step of integrating the compensated error amplified signal with the other signal between the reference signal and the feedback signal includes: converting the fed-back error amplified signal into a compensation signal based on the gain; integrating the compensation signal with the other signal between the reference signal and the feedback signal to reduce the deviation, thereby obtaining the integrated signal.

[0021] In certain embodiments of the fourth aspect of the present application, the step of converting the fed-back error amplified signal into a compensation signal based on the gain includes: buffering the error amplified signal fed back by the switching power supply within at least one switching cycle to output a compensation signal for reflecting the mean signal of the error amplified signal.

[0022] In certain embodiments of the fourth aspect of the present application, the step of integrating the compensation signal with the other signal between the reference signal and the feedback signal for deviation reduction includes: based on the differential method between the integrated signal and the reference signal, adding the acquired reference signal and the compensation signal to obtain the integrated signal; or based on the differential method between the integrated signal and the feedback signal, subtracting the compensation signal from the acquired feedback signal to obtain the integrated signal.

[0023] The fifth aspect of the present application provides a control method for a switch control device, wherein the switch control device changes the electrical signal in the power conversion unit connected to the power supply bus so that the power conversion unit provides stable power supply to the load, wherein the control method includes: obtaining a feedback signal for reflecting the load-side power supply signal, and sampling the induction signal in the power conversion unit; a method for generating an error amplification signal as described in any one of the fourth aspects; performing conduction detection based on the error amplification signal, and controlling the switch unit in the switch control device to be turned on according to the detection result; detecting the sampling signal, and controlling the switch unit in the switch control device to be turned off based on the detection result.

[0024] As described above, the error amplifier circuit of the present application and the applicable switching power supply and method have the following beneficial effects: the error amplifier circuit provided by the present application utilizes the method of compensating the error signal between the feedback signal and the reference signal to effectively eliminate the mismatch between the actual feedback signal and the error amplifier signal required for the stable operation of the switching control device, thereby achieving that the voltage deviation between the feedback signal and the reference signal is independent of the stable range of the error amplifier signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shown is a circuit block diagram of a switching power supply.

[0026] Figure 2 Shown is a circuit structure framework diagram of a switch control device in one embodiment.

[0027] Figure 3 Shown is a circuit structure schematic diagram of a switch control device.

[0028] Figure 4 Displayed as the on-off cycle of the switching unit Figure 3 Schematic diagram of the waveform of the feedback signal sampled by the first sampling module in the circuit structure shown in .

[0029] Figure 5 Shown is a schematic diagram of the circuit structure of a switch on-off cycle detection module in one embodiment.

[0030] Figure 6Shown is another circuit schematic diagram of a switch control device.

[0031] Figure 7 Shown is a signal schematic diagram of the switch control device and the switch unit in the DCM mode.

[0032] Figure 8 Shown is a signal schematic diagram of the switch control device and the switch unit in the QR mode.

[0033] Fig. 9 It is a circuit diagram of a conduction detection unit in a switch control device in another embodiment.

[0034] Fig.10 Shown is a signal schematic diagram of the switch control device and the switch unit in the CCM mode.

[0035] Fig.11 FIG. 4 is a schematic diagram showing a circuit structure of an error amplifier circuit in one embodiment.

[0036] Fig.12 It is a schematic diagram of the circuit structure of the error amplification unit in the error amplification circuit in one embodiment.

[0037] Fig.13 FIG. 4 is a circuit diagram of a compensation unit in the error amplifier circuit in one embodiment.

[0038] Fig.14 FIG. 4 is a circuit diagram showing an error amplifier circuit in one embodiment.

[0039] Fig.15 FIG. 4 is a circuit diagram showing a circuit structure of an error amplifier circuit in another embodiment.

[0040] Fig.16 A flow chart of a method for generating an error amplified signal is shown.

[0041] Fig.17 Shown is a flow chart of a control method for a switch control device. DETAILED DESCRIPTION

[0042] The following is an explanation of the implementation of the present application by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification.

[0043] Although the terms first, second, etc. are used to describe various elements in this article in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first conduction detection signal can be referred to as the second conduction detection signal, and similarly, the second conduction detection signal can be referred to as the first conduction detection signal, without departing from the scope of the various described embodiments. But unless the context clearly indicates otherwise, they are not the same preset threshold.

[0044] Furthermore, as used in this article, the singular forms "one", "an" and "the" are intended to include plural forms as well, unless there is an indication to the contrary in the context. It should be further understood that the terms "comprise", "include" indicate the presence of the described features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition will only occur when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0045] As an energy conversion circuit, a switching power supply provides an intermittent electrical signal to a power conversion unit by turning on and off the switch unit therein. The electrical signal is converted by the power conversion unit to output a stable DC power supply to the load side. In order to ensure stable power supply on the load side, the switch control device in the switching power supply obtains a feedback signal reflecting the load power supply, and adaptively adjusts the on and off of the switch unit according to the feedback signal. The adaptive adjustment includes the switching power supply providing a stable power supply in an adapted mode according to at least the feedback signal obtained. In order to solve the problem that the switching power supply adaptively adjusts the switching frequency, peak current, etc. in different modes, the present application provides a switching power supply and a switch control circuit therein.

[0046] See also Figure 1, which is a circuit block diagram of a switching power supply. The switching power supply includes: a rectifier unit 11, a switch unit 13, a power conversion unit 14 and a switch control device 12. Based on the power supply demand of the switching power supply adaptive load side, the switch control device 12 controls the on-off operation of the switch unit 13, so that the power conversion unit 14 can provide power to the load based on any appropriate mode of DCM mode (Discontinous Conducion Mode), QR mode (Quasi Resonant Mode), or CCM mode (Continuous Conduction Mode).

[0047] The rectifier unit 11 is connected to an external AC power source, and is used to rectify the connected AC power and output it to the power supply bus. The external AC power source is exemplified by an adapter for connecting the AC power grid to the room, such as a socket, a terminal, etc. The rectifier unit 11 includes but is not limited to a full-wave rectifier circuit or a half-wave rectifier circuit. The rectifier unit outputs the rectified electrical signal to the power supply bus. Here, the power supply bus 500 (also known as VBUS) is a power line, which outputs the power supply signal rectified by the rectifier unit 11 to the load side for the load to connect to form a power supply circuit.

[0048] The power supply bus 500 is connected to a switch unit 13 and a power conversion unit 14. The switch unit 13 has a control end (or a driving end), which includes a switch device that is turned on / off based on the voltage or current of the control end. Examples of the switch device are BJT transistors, junction field effect transistors (JFETs), or depletion MOS power tubes.

[0049] The power conversion unit 14 is used to provide stable power supply to the load through the intermittent electrical signal generated by the switch unit. The power conversion unit 14 includes an inductor circuit for converting the intermittent electrical signal into both load power supply and energy storage in the energy storage circuit.

[0050] Here, the inductor circuit includes an inductor, which converts the intermittent electrical signal transmitted by the power supply bus into a variable current through the electromagnetic induction of the inductor to the variable electrical signal, so as to provide energy storage operation for the energy storage circuit. The inductor circuit includes a transformer based on a flyback switching power supply, an inductor based on a BUCK switching power supply, or an inductor based on a Boost switching power supply. The energy storage circuit includes a capacitor, which is used to perform energy storage operation on the electrical signal output by the inductor circuit after energy conversion, and use the discharge operation of the stored electrical energy to provide stable power supply to the load side.

[0051] The switch control device 12 controls the switch unit to be turned on or off by detecting a feedback signal reflecting the power supply on the load side, a feedback signal reflecting the demagnetization operation in the inductor circuit, and a sampling signal reflecting the current peak in the inductor circuit, so as to put the power conversion unit in at least DCM mode or QR mode.

[0052] See also Figure 2 , which is a circuit structure framework diagram of a switch control device in one embodiment. The switch control device 20 comprises: a sampling unit 201 , a conduction detection unit 202 , a disconnection detection unit 203 , and a logic control unit 204 .

[0053] The sampling unit 201 is coupled to the power conversion unit 13, and is used to sample the inductor circuit and output a feedback signal reflecting the inductor circuit outputting power to the load side, and a sampling signal reflecting the current peak value in the inductor circuit.

[0054] Here, the sampling unit is coupled to the inductive circuit in the power conversion unit by means of inductive coupling and / or electrically connected inductance to obtain a feedback signal and / or a sampling signal.

[0055] The sampling unit outputs a sampling signal by sampling the electrical signal in the inductor circuit during the on-state of the switch unit, and outputs a feedback signal by sampling the electrical signal in the inductor circuit during the off-state of the switch unit. In some examples, the sampling unit may sample the input and output of the power conversion unit, respectively, to obtain the feedback signal and the sampling signal, respectively. For example, the sampling unit obtains the sampling signal by sampling the electrical signal flowing from the switch unit to the inductor circuit; the sampling unit obtains the feedback signal by sampling the electrical signal output by the inductor circuit during the off-state of the switch unit.

[0056] For some more examples, see Figure 3 , which is a schematic diagram of a circuit structure of a switch control device, wherein the sampling unit includes a first sampling module 2011 and a second sampling module 2012.

[0057] The first sampling module 2011 is coupled to the inductor circuit 131, and is used to obtain a feedback signal reflecting the load power supply based on sensing the power supply signal output by the inductor circuit 131 to the load side. Figure 3As shown, in a flyback switching power supply, the inductor circuit 131 includes a transformer, and the first sampling module senses the primary winding of the transformer to obtain the feedback signal. For another example, not shown in the figure, in a flyback switching power supply, the first sampling module is connected to the secondary winding of the transformer, and the feedback signal is obtained by using a secondary synchronous rectification circuit connected to the secondary winding. For another example, not shown in the figure, in a BUCK type switching power supply, the inductor circuit includes an inductor, and the first sampling module is electrically connected to the output end of the inductor, or senses the inductor electrical signal in the inductor. Here, the first sampling module can also be called a load feedback unit.

[0058] Some ways of obtaining feedback signals in a power conversion unit using peripheral circuits are as follows: the first sampling module includes an inductance sensor and a voltage divider circuit. Still taking the example that the inductance circuit in the power conversion unit includes a transformer, the inductance sensor (also called an auxiliary winding) is coupled to the primary winding of the transformer and has a preset corresponding relationship with the number of inductance turns of the secondary winding, so that the sensed electrical signal reflects the load-side power supply and outputs a feedback signal. The above-mentioned inductance circuit can also be configured as an inductance circuit based on a BUCK-type switching power supply, or an inductance circuit based on a BOOST-type switching power supply.

[0059] The feedback signal obtained by the inductive coupling method is used to reflect in time sequence: the power supply signal provided by the inductive circuit to the load, and the demagnetization signal of the inductive circuit during the period when the switch unit is disconnected. Figure 4 , which is shown as the on-off cycle of the switching unit Figure 3 The waveform diagram of the feedback signal sampled by the first sampling module in the circuit structure shown in FIG. During the period when the switch unit is disconnected based on the switch control signal Gate, the magnetic energy accumulated by the transformer and the auxiliary winding is converted into electric energy output by the secondary winding and the inductive sensor, that is, the secondary winding and the inductive sensor are both in the demagnetization process, wherein, affected by the demagnetization process of the secondary winding, such as Figure 4 As shown, the feedback signal output by the inductive sensor is V FB As shown, the time period t1 corresponds to the power supply signal during the secondary winding supplying power to the load, and the time period t2 corresponds to the demagnetization signal during the demagnetization operation of the secondary winding. The feedback signal output by the inductance sensor is divided by the voltage divider circuit and then output to the conduction detection unit.

[0060] The second sampling module 2012 in the sampling unit is electrically connected to an output terminal of the inductor circuit and is used to sample the peak value of the current flowing through the inductor circuit to obtain the sampling signal. The second sampling module samples the electrical signal during the excitation period of the inductor circuit.

[0061] Here, the second sampling module includes a sampling circuit for sampling a voltage signal, which is connected between the output end of the inductor in the inductor circuit that generates a current peak based on the intermittent electrical signal and a reference voltage terminal, and outputs the sampling signal. Wherein, the intermittent electrical signal is a rectified signal output by the power supply bus during the conduction period of the switch unit. The second sampling module samples the rectified signal of the inductor circuit during the conduction period of the switch unit and outputs it as a sampling signal to the disconnection detection unit. Wherein, the reference voltage terminal takes the voltage ground GND as an example, and it can also be a circuit terminal that provides a constant voltage. Taking the inductor circuit including a transformer as an example, the second sampling module is connected between the output end of the primary winding of the transformer and the voltage ground, wherein the end connected to the primary winding outputs the sampling signal.

[0062] It should be noted that, in a BUCK-type (or BOOST-type) switching power supply, the inductance circuit connected to the second sampling module corresponds to the inductance connected to the switch unit in the BUCK-type (or BOOST-type) switching power supply.

[0063] By using the sampled feedback signal and the sampling signal, the on-detection unit in the switch control device is used to detect the on-time of the switch unit, and the off-detection unit in the switch control device is used to detect the off-time of the switch unit.

[0064] The conduction detection unit is coupled to the sampling unit and is used to detect the feedback signal in different time periods and output a first conduction detection signal and a second conduction detection signal based on the detection results.

[0065] Here, according to the different signal types that the feedback signal can reflect in different time periods during the period when the switch unit is disconnected, the conduction detection unit detects the different types of signals represented by the feedback signal in a time sequence, and outputs the corresponding first conduction detection signal and second conduction detection signal. For example, the conduction detection unit detects the load-side power supply based on the feedback signal obtained in the first time period, and outputs the first conduction detection signal according to the detection result; and detects the end time of demagnetization of the inductor circuit based on the feedback signal obtained in the second time period, and outputs the second conduction detection signal according to the detection result. Figure 4 Taking the signal waveform diagram shown as an example, the feedback signal reflects the load power supply in the t1 period (i.e., the first period), and reflects the secondary winding demagnetization operation in the t2 or (t1+t2) period (i.e., the second period) until the demagnetization is completed.

[0066] based on Figure 3 As shown in the circuit framework, the conduction detection unit 202 includes a switch on-off cycle detection module and a demagnetization detection module (both not shown).

[0067] The switch on-off cycle detection module is connected to the sampling unit and obtains a reference signal V ref_FB , for use during a first period based on the reference signal V ref_FB The feedback signal is detected, and the first conduction detection signal is output based on the detection result; wherein the first conduction detection signal is used to adjust the on-off cycle of the switch unit. For example, the first conduction detection signal is used to adjust the on-time of the switch unit in at least one continuous on-off cycle.

[0068] Among them, the reference signal V ref_FB The switch on-off cycle detection module can be set based on the constant voltage power supply of the switch power supply to the load side. ref_FB A part of the feedback signal that reflects the power supply to the load side is detected to determine the power supply deviation on the load side, and the corresponding power supply deviation is reduced by adjusting the on-off cycle of the switch unit, thereby achieving stable power supply on the load side.

[0069] See also Figure 5 , which is a schematic diagram of the circuit structure of the switch on-off cycle detection module in one embodiment. The switch on-off cycle detection module includes: an error amplifier circuit 311, a switch on-off cycle timing circuit 312, and a time limit circuit 313. Among them, the error amplifier circuit 311 is controlled by the time limit circuit 312, that is, the timeout signal output by the time limit circuit is used to control the error amplification signal output by the error amplifier circuit not to change due to the change of the feedback signal.

[0070] The time limit circuit 313 is connected to the error amplifier circuit 311, and is used to time the first time period based on the disconnection operation of the switch unit, and output a timeout signal when the timing times out; wherein the timeout signal is used to limit the error amplifier circuit from receiving the feedback signal.

[0071] The time-limiting circuit 313 may allow an input terminal of the error amplifier circuit to receive a feedback signal during the timing period, and prohibit the error amplifier circuit from receiving the feedback signal when the timing is overdue, and the voltage of the feedback signal received before the timeout is maintained by the error amplifier circuit 311. To this end, in some examples, the time-limiting circuit includes a capacitor for timing and a first control circuit and a second control circuit of the capacitor, wherein the first control circuit and the second control circuit are switched according to a switch control signal of a switch unit, and when the switch control signal indicates that the switch unit is disconnected, the first control circuit of the time-limiting circuit operates to start the timing operation until the voltage of one plate of the capacitor reaches a timing threshold voltage and the timing is overdue. When the switch control signal indicates that the switch unit is turned on, the second control circuit of the time-limiting circuit operates to start resetting the timing capacitor. The first control circuit and the second control circuit correspond to one of a charging circuit and a discharging circuit of the timing capacitor.

[0072] It should be noted that the circuit structure for performing timing operations in the time-limited circuit is not limited to using charging circuit timing or discharging circuit timing, but can also be combined with circuit structures with mismatched charging and discharging capabilities to perform timing operations, which will not be described in detail here.

[0073] In other examples, the time-limiting circuit includes a clock signal generator, a timing counter, a first control circuit, and a second control circuit, wherein the first control circuit controls the timing counter to start counting the clock signal output by the clock signal generator based on a switch control signal that disconnects the switch unit, and when the voltage corresponding to the count value reaches a timing threshold voltage, the timing times out; and the second control circuit resets the timing counter based on the switch control signal that turns on the switch unit.

[0074] It should be noted that the circuit structure for performing timing operations in the time-limited circuit is not limited to using the voltage corresponding to the count value reaching a timing threshold voltage as a timing timeout condition, and the timing timeout condition can also be determined by detecting counter overflow, etc., which will not be described in detail here.

[0075] It should also be noted that the time-limited circuits in the above examples may simultaneously include a timing circuit structure provided with a timing counter and a timing capacitor to cope with situations such as unstable timing threshold voltage, and use the timing logic represented by the digital circuit structure to output a first conduction detection signal based on the timing timeout signal of the two timing circuit structures. Among them, the digital circuit structure includes one or more of the following circuit combinations: a trigger, a logic AND gate, a logic NOT gate, a logic OR gate, a comparator, etc.

[0076] Under the control of the time-limiting circuit, the feedback signal V received by the error amplifier circuit 311 is FBThe first input terminal of the error amplifier circuit 311 is connected to the sampling unit to obtain the feedback signal V FB , the second input terminal receives the reference signal V REF1 .

[0077] Here, the error amplifier circuit 311 includes at least an error amplifier and a buffer, wherein the buffer is connected to the time limit circuit and is used to maintain the voltage of the input or output of the error amplifier before receiving the timeout signal based on the received timeout signal. To this end, the buffer can be located at the input or output of the error amplifier. The error amplifier is used to provide an error amplified signal between the feedback signal and the reference signal. In some examples, the reference signal V REF1 The feedback signal V FB The output of the error amplifier circuit is amplified based on the gain of the error amplifier (V REF1 -V FB ) The error amplified signal V COMP In some other examples, the error amplifier circuit further includes an inverter, and the reference signal V REF1 The feedback signal V FB The first input terminal is transmitted to the positive input terminal of the error amplifier through the buffer, and is inverted by the inverter. The output terminal of the error amplifier circuit still outputs the amplified value (V REF1 -V FB ) The error amplified signal V COMP The error amplified signal V obtained in the above examples COMP Transmitted to the switch on-off cycle timing circuit.

[0078] It should be noted that the signals outputted by the input side and the output side of the error amplifier circuit are designed according to the requirements of the corresponding previous circuit output and subsequent circuit input. Therefore, the above examples are only for illustration and not for limitation of the present application.

[0079] The switch on-off cycle timing circuit 312 is connected to the output end of the error amplifier circuit, and is used to perform switch on-off cycle timing based on the error amplified signal, and output a first conduction detection signal when the timing times out. In some specific examples, the switch on-off cycle timing circuit 312 can be based on the error amplified signal V COMPThe on-time of the switch unit is timed, and the on-off cycle of the switch unit is adjusted by adjusting the on-time. In some other specific examples, the switch on-off cycle timing circuit can also be based on the error amplification signal V COMP The duration of an on-off cycle of the switch unit is timed, and the on-off cycle of the switch unit is adjusted by adjusting the duration of the on-off cycle.

[0080] In some examples, the switch on-off cycle timing circuit includes a timing capacitor, and a first control circuit and a second control circuit connected to the timing capacitor and receiving the error amplification signal. Here, the circuit structure of the switch on-off cycle timing circuit using the timing capacitor to time the switch unit conduction interval is similar to the circuit structure of the timing capacitor in the aforementioned time-limiting circuit to time the first time period, and will not be described in detail here. The difference is that the timing threshold voltage set in the switch on-off cycle timing circuit is based on the error amplification signal V COMP And it is certain.

[0081] In some other examples, the switch on-off cycle timing circuit includes a timing counter, and a counter control circuit connected to the timing counter and receiving the error amplification signal. Here, the circuit structure of the switch on-off cycle timing circuit using the timing counter to time the switch unit conduction interval is similar to the circuit structure of the aforementioned time limit circuit using the timing counter to time the first time period, and will not be described in detail here. The difference is that the timing timeout conditions including the timing threshold voltage and the timer overflow condition set in the switch on-off cycle timing circuit are based on the error amplification signal V COMP For example, the counter control circuit in the switch on-off cycle timing circuit is based on the error amplification signal V COMP Select a counter with a corresponding number of bits, and detect when the selected counter overflows, to determine the timing timeout. For another example, the counter control circuit in the switch on-off cycle timing circuit converts the current count value of the timing counter into a voltage value, and compares it with the error amplification signal V COMP A comparison is performed to determine a timing timeout based on the comparison result.

[0082] According to actual design requirements, the switch on-off cycle timing circuit may also include a timing circuit structure provided with a timing counter and a timing capacitor to respond to, for example, the error amplification signal V COMP The voltage is unstable, and the first conduction detection signal is output based on the timing timeout signal of the two timing circuit structures by using the logic circuit structure. Among them, the logic circuit structure includes one or more of the following circuit combinations: a trigger, a logic AND gate, a logic NOT gate, a logic OR gate, a comparator, etc.

[0083] Based on the circuit structures shown in the above examples, the working process of the switch on-off cycle detection module is as follows: during the disconnection period of the switch unit, the time limit circuit triggers the timing of the first period based on the invalid switch control signal of the switch unit. During the timing period, the error amplifier circuit amplifies the error signal between the reference signal and the feedback signal based on the preset gain and outputs the error amplification signal V COMP The switch on-off cycle timing circuit is based on the invalid trigger timing of the driving signal of the switch unit, and uses the error amplification signal V COMP Determine that the timing has timed out, thereby changing the on-off cycle of the switch unit.

[0084] See also Figure 6 , which is another circuit diagram of the switch control device, the conduction detection unit further includes a demagnetization detection module 321, the demagnetization detection module 321 is connected to the sampling unit and obtains a zero-crossing reference signal V REF_Z , used to detect the signal of the second time period in the feedback signal based on the zero-crossing reference signal, and output the second conduction detection signal based on the detection result; wherein the second conduction detection signal is used to indicate that the demagnetization of the inductor circuit in the power conversion unit is completed. Wherein, the zero-crossing reference signal is a built-in reference signal with a voltage of zero or slightly greater than zero.

[0085] Here, Figure 3 The switch control device shown and Figure 4 Taking the signal waveform diagram shown in FIG. 1 as an example, based on the demagnetization operation of the primary winding in the transformer, the inductor sensor converts the induced magnetic energy into electrical energy. When the demagnetization operation is completed, the voltage of the feedback signal output after conversion is close to zero. To this end, the demagnetization detection module detects the signal of the second time period in the feedback signal based on the zero-crossing reference signal.

[0086] The demagnetization detection module includes a comparison circuit and a shielding circuit. One input end of the comparison circuit receives a zero-crossing reference signal, and the other input end receives the feedback signal, and when the voltage of the feedback signal drops to the zero-crossing reference signal, the second conduction detection signal is output. The shielding circuit is used to detect the conduction detection signal when the comparison circuit outputs the second conduction detection signal. Figure 4 The zero crossing point V Z The oscillating feedback signal is then shielded to reduce false triggering of the demagnetization detection.

[0087] During the period when the switch unit is disconnected, affected by the mutual inductance between the primary and secondary windings of the transformer and the electromagnetic sensor, after the demagnetization operation of the secondary winding is completed, the inductance sensor still outputs the oscillating signal generated by induction, that is, Figure 4To this end, when the comparison circuit detects the zero-crossing voltage of the feedback signal for the first time during the disconnection period of the switch unit, the output second conduction detection signal (i.e., demagnetization detection signal) triggers the shielding circuit, which is a timing circuit. When the timing is overtime, the output timeout signal is used to shield the comparison circuit from outputting the first conduction detection signal, or shield the logic control unit from responding to the second conduction detection signal to normally turn on the switch unit.

[0088] The disconnection detection unit 203 is coupled to the second sampling module 2012 in the sampling unit, and is configured to detect the sampling signal based on the feedback signal and output a disconnection detection signal based on the detection result.

[0089] Here, the disconnection detection unit 203 generates a peak reference signal for detecting the conduction of the switch unit based on the feedback signal, performs disconnection detection on the sampling signal, and outputs a disconnection detection signal corresponding to the detection result.

[0090] In some embodiments, the disconnection detection unit includes a disconnection signal generation module and a peak detection module. The disconnection signal generation module receives the feedback signal and outputs a peak reference signal generated based on the feedback signal. The first input terminal of the peak detection module is connected to the sampling unit to obtain a sampling signal, and the second input terminal receives the peak reference signal, and is used to detect the sampling signal based on the peak reference signal, and output a disconnection detection signal based on the detection result.

[0091] Here, the peak detection module starts to detect the sampling signal when the switch unit is turned on. The peak detection module uses the switch control signal output by the logic control unit for controlling the switch unit to be turned on as an enable signal, and detects the sampling signal when the enable signal is valid. When it is detected that the level value of the sampling signal reaches the level value of the peak reference signal, the disconnection detection signal for effective identification by the logic control unit is output. For example, the peak detection module detects the sampling signal when the enable signal is valid. When it is detected that the level value of the sampling signal reaches the level value of the peak reference signal, the disconnection detection signal output by the peak detection module changes from a low level to a high level, and the logic control unit regards the high level as a valid signal to output a switch control signal that disconnects the switch unit. The peak detection module can also start to detect the sampling signal when receiving a timeout signal output by the time limit circuit. For example, the peak detection module is controlled by the enable signal, that is, the detection sampling signal is triggered based on the timeout signal (enable signal) output by the time limit circuit.

[0092] In yet another embodiment, different from the above-mentioned embodiment, the second input terminal of the peak detection module is connected to the conduction detection unit to obtain a peak reference signal related to the feedback signal generated in the conduction detection unit.

[0093] Combination Figure 6 As shown, the peak detection module 411 is connected to the error amplifier circuit 311 in the conduction detection unit, and the error amplification signal is used as the peak reference signal. The comparison circuit in the peak detection module compares the received peak reference signal with the sampling signal V CS And output the disconnection detection signal.

[0094] To output a disconnection detection signal, the peak detection module at least comprises a comparison circuit, wherein a first input terminal of the comparison circuit receives the sampling signal, a second input terminal receives the peak reference signal, and an output terminal outputs a disconnection detection signal obtained by comparing the voltage of the sampling signal with the voltage of the peak reference signal.

[0095] The comparison circuit comprises a comparator. The positive input terminal of the comparator receives a peak reference signal, and the negative input terminal receives a sampling signal. When the voltage of the sampling signal does not reach the voltage of the peak reference signal, the comparator outputs a disconnection detection signal represented by a low voltage; when the voltage of the sampling signal reaches the voltage of the peak reference signal, the comparator outputs a disconnection detection signal represented by a high voltage.

[0096] It should be noted that the disconnection detection signal output by the comparison circuit is set according to the signal recognition needs of the subsequent logic control unit. In other examples, the negative input terminal of the comparison circuit receives the peak reference signal and the positive input terminal receives the sampling signal. Based on the above examples, according to the recognition requirements of the subsequent logic control unit for the disconnection detection signal, the comparison circuit may also include an isolator, a latch, etc.

[0097] The first conduction detection signal, the second conduction detection signal, and the disconnection detection signal respectively output by the conduction detection unit and the disconnection detection unit mentioned in the above examples are transmitted to the logic control unit.

[0098] The logic control unit is used to control the switch unit to be turned on / off in the DCM mode or the QR mode based on the control logic of the disconnection detection signal, the first conduction detection signal and the second conduction detection signal.

[0099] Here, in order to adapt to different connected loads and provide stable power supply for them, the timing of the logic control unit outputting the switch control signal for conduction to the switch unit is based on the timing of receiving the signal later than the first conduction detection signal and the second conduction detection signal. Therefore, when the first conduction detection signal is received later than the second conduction detection signal, the logic control unit controls the switch unit to operate in the DCM mode; when the second conduction detection signal is received later than the first conduction detection signal, the logic control unit controls the switch unit to operate in the QR mode.

[0100] To this end, the logic control unit includes at least a logic AND device. When both input ends of the logic AND device are at a high level, it indicates that the first conduction detection signal and the second conduction detection signal have been received, and the logic AND device outputs a high level signal; the logic circuit connected to the logic AND device in the logic control unit outputs a switch control signal for turning on the switch unit based on the high level signal output by the logic AND device. In other words, the switch unit performs a conduction operation based on the switch control signal.

[0101] See also Figure 7 , which is a schematic diagram of the switch control device signal when the load side is lightly loaded, wherein the switch on-off cycle circuit in the conduction detection unit is based on the feedback signal V FB The error amplified signal V COMP The switch on-off cycle is timed, and the timing duration is greater than the duration of the demagnetization detection circuit in the conduction detection unit to detect the demagnetization operation, that is, the second conduction detection signal precedes the first conduction detection signal, and the logic control unit outputs a switch control signal for turning on the switch unit based on the logic AND of the first conduction detection signal and the second conduction detection signal. Based on the switch control signal for turning on the switch unit, the disconnection detection unit starts to detect the sampling signal CS sampled from the output end of the switch unit, and based on the peak reference signal V generated by the feedback signal reflecting the load power supply COMP , detects the peak level of the sampling signal CS to determine the current I flowing through the inductor in the power conversion unit pk When the level of the sampling signal CS reaches the level corresponding to the peak reference signal, the current I is determined. pk When the peak value of the switching voltage reaches a preset peak value, the disconnection detection unit outputs a disconnection detection signal, and the logic control unit outputs a switch control signal for disconnecting the switch unit based on the disconnection detection signal.

[0102] Based on the on and off control of the switch unit by the switch control device provided in the above example, when the switch control device generates the second on detection signal first and then generates the first on detection signal, the current I flowing through the inductor in the power conversion unit pk The waveform is as Figure 7 The waveform of the sampling signal CS is shown, and the waveform example reflects that the switching power supply is in DCM mode.

[0103] See also Figure 8 , which is shown as a resistance greater than Figure 7 The schematic diagram of the signal in the switch control device and the switch unit under the light load condition is shown, wherein the switch on-off cycle circuit in the conduction detection unit amplifies the error signal V generated based on the feedback signal COMP The switch on-off cycle is timed. As the power consumption on the load side increases, the timing duration is less than or equal to the duration of the demagnetization detection circuit in the conduction detection unit detecting the demagnetization operation, that is, the second conduction detection signal does not precede the first conduction detection signal. The logic control unit outputs a switch control signal for turning on the switch unit based on the logic AND of the first conduction detection signal and the second conduction detection signal. Based on the switch control signal for turning on the switch unit, the disconnection detection unit starts to detect the sampling signal CS sampled from the output end of the switch unit, and based on the peak reference signal V generated by the feedback signal reflecting the load power supply COMP , detects the peak level of the sampling signal CS to determine the current I flowing through the inductor in the power conversion unit pk When the level of the sampling signal CS reaches the level corresponding to the peak reference signal, the current I is determined. pk When the peak value of the switching voltage reaches a preset peak value, the disconnection detection unit outputs a disconnection detection signal, and the logic control unit outputs a switch control signal for disconnecting the switch unit based on the disconnection detection signal.

[0104] Based on the on and off control of the switch unit by the switch control device provided in the above example, when the on detection signal in the switch control device first generates the first on detection signal and then generates the second on detection signal, it is equivalent to that there is no interval between the demagnetization stage and the excitation stage of the power conversion circuit, and the current I flowing through the inductor in the power conversion unit is used. pk The waveform description is as follows Figure 8 The waveform of the sampling signal CS is shown, which reflects that the switching power supply is in the QR mode.

[0105] The switch control device can provide a stable power supply adapted to the connected load according to the change of the load side resistance. In order to provide the above functions, the logic control unit includes logic devices such as triggers and latches in addition to the logic and device. According to the connection configuration of the corresponding logic devices, the logic control unit may also include inverters, buffers, etc. For example, the logic control unit includes: a first latch and a second latch corresponding to receiving the first conduction detection signal and the second conduction detection signal, a logic and device connected to the first latch and the second latch, and a trigger connected to the logic and device. Among them, the first latch and the second latch respectively latch the received first conduction detection signal and the second conduction detection signal and output the corresponding latch signal, and the two latch signals corresponding to the first conduction detection signal and the second conduction detection signal are output to the two input ends of the logic and device. When both input ends correspond to the high level of the logic and device, the logic and device outputs a high level signal to trigger the set end of the trigger, so that the trigger outputs a switch control signal for turning on the switch unit. In addition, the reset terminal of the trigger receives a disconnection detection signal, so that the trigger outputs a switch control signal for turning on the switch unit when the disconnection detection signal is received.

[0106] Based on the above examples, in order to adapt to wider load side changes and provide stable power supply, for example, when the load side is connected to a load with a larger resistance, the QR mode power supply requires the inductor and energy storage circuit in the power conversion unit to be adapted and adjusted, otherwise the power supply needs of the load side cannot be met. Examples of connected loads include tablet computers, laptops, etc. For this purpose, please refer to Fig. 9 , which is a circuit diagram of the conduction detection unit in the switch control device in another embodiment. The conduction detection unit in the switch control device also includes: a CCM mode switch on-off cycle timing module 314, which is connected to the logic control unit, and is used to perform CCM mode (Continuous Conduction Mode) switch on-off cycle timing when the switch unit is turned on, and output a third conduction detection signal when the timing times out. The logic control unit in the switch control device also performs conduction control on the switch unit based on the first conduction detection signal, the second conduction detection signal and the third conduction detection signal. In conjunction with the disconnection control triggered by the disconnection detection signal, in other words, the logic control unit controls the switch unit to turn on / off in DCM mode, QR mode, or CCM mode based on the control logic of the disconnection detection signal, the first conduction detection signal, the second conduction detection signal and the third conduction detection signal.

[0107] Here, the CCM mode switch on-off cycle timing module uses the switch control signal of the conducting switch unit as a trigger signal to perform CCM mode switch on-off cycle timing. The CCM mode switch on-off cycle timing starts when the switch unit is conducting and ends when a fixed time is counted. When the timing times out, a third conduction detection signal is output. The set timing time is less than the maximum value of the switch on-off cycle in the QR mode.

[0108] Here, the timing circuit in the CCM mode switch on-off cycle timing module is similar to the aforementioned switch on-off cycle timing circuit. Different from the circuit structure of the aforementioned switch on-off cycle timing circuit, the timing circuit in the CCM mode switch on-off cycle timing module performs a reset operation based on the signal generated after the second conduction detection signal and the first conduction detection signal during the timing period. For example, the CCM mode switch on-off cycle timing module also receives a logic signal output by a logic and device in a logic control module, and performs a reset operation based on the logic signal.

[0109] Taking the CCM mode switch on-off cycle timing module as an example, the first control circuit of the timing capacitor starts to control the timing capacitor based on the switch control signal that turns on the switch unit, so that the voltage of one of the electrodes approaches a reference voltage for timing operation. If the CCM mode switch on-off cycle timing module does not receive the logic signal output by the logic and device in the logic control module throughout the entire timing cycle, then when the voltage of the electrode reaches the corresponding reference voltage, the comparison result output by the comparison circuit in the CCM mode switch on-off cycle timing module changes from one level state to another level state, and the state change indicates timing timeout. The signal output by the comparison circuit for describing the timing timeout is the third conduction detection signal. If the CCM mode switch on-off cycle timing module receives the logic signal output by the logic and device in the logic control module before the timing timeout, the second control circuit of the timing capacitor controls the timing capacitor to perform a reset operation based on the logic signal, so that the comparison result output by the comparison circuit does not indicate timing timeout.

[0110] Taking the CCM mode switch on-off cycle timing module as an example, the first control circuit of the timing counter starts to control the timing counter based on the switch control signal that turns on the switch unit, so that the timing counter approaches a counting threshold to perform a timing operation. If the CCM mode switch on-off cycle timing module does not receive the logic signal output by the logic and device in the logic control module throughout the entire timing cycle, when the count value of the timing counter reaches the counting threshold, the digital-to-analog conversion circuit in the CCM mode switch on-off cycle timing module converts the count value and the counting threshold into voltage signals in real time, and inputs them to the two input ends of the comparison circuit. The comparison result output by the comparison circuit changes from one level state to another level state. The state change indicates that the timing is overtime, and the signal output by the comparison circuit for describing the timing timeout is the third conduction detection signal. If the CCM mode switch on-off cycle timing module receives the logic signal output by the logic and device in the logic control module before the timing is overtime, the reset circuit of the timing counter controls the timing counter to perform a reset operation based on the logic signal, so that the comparison result output by the comparison circuit does not indicate a timing timeout.

[0111] Correspondingly, the logic control unit further includes a logic or device based on the above examples, and the two input ends of the logic or device receive the logic signal output by the logic and device and the third conduction detection signal respectively, and the logic or device controls the trigger to output a switch control signal for turning on the switch unit based on the logic signal or the third conduction detection signal received first. When the third conduction detection signal reaches the logic control unit before the logic signal, it means that the switch unit is controlled to be turned on before the demagnetization operation of the power conversion unit is completed, in other words, the power conversion unit is in CCM mode; when the logic signal reaches the logic control unit before the third conduction detection signal, it means that the switch unit is controlled to be turned on after the demagnetization operation of the power conversion unit is completed, in other words, the power conversion unit is in DCM mode or QR mode.

[0112] Each example of the above switch control device is configured with a self-power supply unit, which is used to power the active devices in the phase switch control device. Among them, examples of active devices include a current source for generating a constant voltage signal, a control circuit for a capacitor for outputting a charging signal, an error amplifier, etc. The self-power supply unit is coupled to the power supply bus to store electrical energy. In some examples, the self-power supply unit may be configured with a separate energy storage module and a charging module, wherein one end of the charging circuit is connected to the power supply bus, the other end is connected to the energy storage module, and the other end of the energy storage module is connected to the VCC port in the switch control device to provide internal power supply. In other examples, the self-power supply unit obtains electrical energy using the existing circuit structure in the switch control device. For example, the self-power supply unit is connected to an inductive sensor, and energy is stored by the electrical signal output by the inductive sensor to provide internal power supply. To this end, the self-power supply unit includes an energy storage module and a unidirectional conduction module. The energy storage module is connected to the output end of the inductive sensor, and is used to provide internal power supply for the switch control device by the electrical signal output by the inductive sensor. The unidirectional conduction module is arranged on the line between the output end of the inductive sensor and the energy storage module. The energy storage module includes a capacitor and a charging circuit, wherein the charging circuit is connected between the output end of the inductive sensor and one plate of the capacitor, the other plate of the capacitor is connected to the VCC terminal, and the unidirectional conduction module is provided on the charging circuit. Here, the unidirectional conduction module includes a diode as an example.

[0113] Based on the above examples and combined Fig. 9 and Fig.10When the switching power supply provided by the present application is connected to a load with a large resistance (such as a tablet computer) and charges it, the working process of any switch on-off cycle thereof is exemplified as follows: During the period when the switch unit is disconnected, the switch on-off cycle detection module in the conduction detection unit will obtain the feedback signal of the self-inductance sensor in the first period and a reference signal for error amplification processing and time the switch unit on-time based on the generated error amplification signal, and output the first conduction detection signal when the timing times out. At the same time, the demagnetization detection module in the conduction detection unit also obtains the feedback signal from the inductance sensor, detects the first zero-crossing moment of the feedback signal based on the zero-crossing reference signal, and outputs the second conduction detection signal. In order to prevent multiple zero-crossings caused by subsequent vibrations of the feedback signal, the demagnetization detection module shields the feedback signal based on the output second conduction detection signal, so that the demagnetization detection module outputs the second conduction detection signal once in the second period from the switch unit disconnection to the shielding. During the period when the switch unit is disconnected, the CCM mode switch on-off cycle timing module in the conduction detection unit also starts the CCM mode switch on-off cycle. The logic control unit is provided with a logic AND and a logic OR device, wherein the two input ends of the logic AND device receive the first conduction detection signal and the second conduction detection signal respectively, and the logic OR device receives the logic signal and the third conduction detection signal output by the logic AND device respectively. According to the load side power supply situation reflected by the feedback signal, the demagnetization detection module detects that the time spent at the feedback signal zero-crossing moment and / or the timing time of the switch on-off cycle detection module is greater than the timing time of the switch on-off cycle timing module in the CCM mode. Therefore, when the logic control unit receives the third conduction detection signal, the logic signal received by the logic OR device is a low level and the third conduction detection signal is a high level, so the high level output by the logic OR device triggers the trigger in the logic control unit to output the switch control signal that turns on the switch unit. During the conduction period of the switch unit, the electrical signal in the power supply bus is transmitted to the power conversion unit, the inductance circuit in the power conversion unit enters the excitation operation, and the energy storage circuit mainly maintains the load power supply. The switch control signal is also output to the disconnection detection unit. The disconnection detection unit uses the error amplification signal as a peak reference signal to detect the sampling signal output from the switch unit to the power conversion unit. When the voltage of the sampling signal reaches the voltage of the peak reference signal, the disconnection detection signal is output to the logic control unit. The trigger in the logic control unit outputs a switch control signal to disconnect the switch unit based on the disconnection detection signal. During the disconnection of the switch unit, the inductor circuit in the power conversion unit enters a demagnetization operation, and the electrical signal generated by the demagnetization operation is output to the load side and the energy storage circuit, wherein the energy storage circuit performs an energy storage operation to maintain power supply to the load during the later stage of the deduction operation and the excitation operation in the next switching cycle. The switch control device controls the on and off of the switch unit based on the above control process, so that the electrical signal in the inductor circuit in the power conversion unit appears as follows in the CCM mode. Fig.10 The waveform of the sampling signal CS is shown.

[0114] As the charge stored in the load increases, its resistance gradually decreases, and the switch control device's detection of the switch on-off cycle, peak value detection, etc. based on the feedback signal also changes accordingly. In a certain switching cycle, during the period when the switch unit is disconnected, when the switch on-off cycle detection module outputs a first conduction detection signal, and the demagnetization detection module outputs a second conduction detection signal, and the first conduction detection signal is output to the logic control unit before the second conduction detection signal, the CCM mode switch on-off cycle timing module has not timed out, and the logic and device in the logic control unit outputs a logic signal represented by a high level when receiving the first conduction detection signal and the second conduction detection signal, and the logic or device outputs a high level signal to the trigger based on the logic signal, and the trigger outputs a switch control signal that turns on the switch unit, and the switch control signal is also output to the CCM mode switch on-off cycle timing module and the disconnection detection unit at the same time; wherein the CCM mode switch on-off cycle timing module resets the timing based on the switch control signal; the disconnection detection unit detects the sampling signal output from the switch unit to the power conversion unit with the error amplification signal as the peak reference signal, and when the voltage of the sampling signal reaches the voltage of the peak reference signal, the disconnection detection signal is output to the logic control unit; the trigger in the logic control unit outputs a switch control signal that turns off the switch unit based on the disconnection detection signal. Based on the above control logic, the on-off of the switch unit causes the inductor circuit in the power conversion unit to enter the excitation operation immediately after the demagnetization operation ends, which makes the waveform of the inductor circuit in the power conversion unit as shown in FIG. Figure 8 As shown in the waveform of the sampling signal CS, the switching power supply is in QR mode.

[0115] When the load charging is finished, the load resistance continues to decrease, which is equivalent to the switching power supply being in a light-load state. In a certain switching cycle, during the disconnection period of the switch unit, when the switch on-off cycle detection module outputs the first conduction detection signal, and the demagnetization detection module outputs the second conduction detection signal, and the first conduction detection signal is output to the logic control unit later than the second conduction detection signal, the CCM mode switch on-off cycle timing module has not timed out, and the logic and device in the logic control unit outputs a logic signal represented by a high level when receiving the first conduction detection signal and the second conduction detection signal, and the logic or device outputs a high level signal to the trigger based on the logic signal. A trigger outputs a switch control signal that turns on the switch unit, and the switch control signal is also output to the CCM mode switch on-off cycle timing module and the disconnection detection unit at the same time; wherein the CCM mode switch on-off cycle timing module resets the timing based on the switch control signal; the disconnection detection unit detects the sampling signal output from the switch unit to the power conversion unit with the error amplification signal as the peak reference signal, and when the voltage of the sampling signal reaches the voltage of the peak reference signal, it outputs a disconnection detection signal to the logic control unit; the trigger in the logic control unit outputs a switch control signal that turns off the switch unit based on the disconnection detection signal. Based on the above control logic, the turning on and off of the switch unit causes the inductor circuit in the power conversion unit to have a time slot interval after the demagnetization operation ends until the switch on-off cycle timing ends, which makes the waveform of the inductor circuit in the power conversion unit as shown in the figure Figure 7 As shown in the waveform of the sampling signal CS, the switching power supply is in DCM mode.

[0116] As can be seen from the above example, the switching power supply can adaptively match different connected loads, thereby providing the loads with a stable power supply that matches the power supply thereof.

[0117] In the conduction detection unit provided in the present application, the reference signal received by the error amplifier circuit used can be provided by the power supply inside the switch control device, which is usually configured based on the charging requirements of the switch power supply and its load at the factory. When the reference signal provides a fixed level, the error amplifier circuit performs switching cycle timing based on the level difference between the feedback signal and the reference signal. The first conduction detection signal output when the timing times out affects the conduction timing of the switch unit. When the switch unit performs the conduction operation based on the first conduction detection signal, the power supply output by the power conversion unit to the load side will also change at any time. The specific changes are as follows: When the power supply output by the power conversion unit is lower than the power supply corresponding to the reference signal, the conduction time determined by the conduction detection unit based on the error amplification signal becomes longer, which increases the power supply output by the power conversion unit, that is, the power supply level output by the power conversion unit is close to the power supply level corresponding to the reference signal. When the power supply level output by the power conversion unit is close to the power supply level corresponding to the reference signal, the difference between the feedback signal received by the error amplifier circuit and the reference signal decreases, so that the conduction time determined by the conduction detection unit based on the error amplifier signal becomes shorter, and the power supply output by the power conversion unit decreases, that is, the difference between the power supply level output by the power conversion unit and the power supply level corresponding to the reference signal increases. One of the reasons for the above jitter and unstable power supply is that the error amplifier circuit provides the error amplification signal V used to maintain the load power supply within the normal power supply range due to the change in the resistance of the load. COMP The difference between the feedback signal input to the error amplifier circuit and the reference signal does not match.

[0118] From the above examples, it can be seen that when a switching power supply that uses a fixed reference signal for power supply is connected to a load that does not match the factory configuration, or when the resistance of the connected load changes, the output power supply is lower than the normal power supply and has a large jitter according to the change in resistance. This kind of inability to provide stable power supply within the normal range and the output power supply has a large jitter is also reflected in the situation that the external AC power supply connected to the switching power supply does not match the factory configuration.

[0119] To solve the above defects, the present application also provides an error amplifier circuit. The error amplifier circuit is not only applicable to the switching power supply examples described above in the present application, but also applicable to any single mode or other at least two modes of switching power supply.

[0120] See also Fig.11, which is a schematic diagram of the circuit structure of the error amplifier circuit in one embodiment. The error amplifier circuit includes a first input terminal 532 and a second input terminal 531, which are used to receive a reference signal and a feedback signal respectively. Among them, the first input terminal can be the positive input terminal of the error amplifier circuit, and the second input terminal is the negative input terminal of the error amplifier circuit. According to the circuit structure inside the error amplifier circuit, the first input terminal can also be the negative input terminal of the error amplifier circuit, and the second input terminal is the positive input terminal of the error amplifier circuit. The output terminal 533 of the error amplifier circuit outputs the error amplification signal.

[0121] To this end, the error amplification circuit includes: an error amplification unit 510 and a compensation unit 520. Here, the error amplification unit and the compensation unit may also be referred to as an error amplification sub-circuit and a compensation sub-circuit.

[0122] The error amplifier unit 510 has a positive input terminal, a negative input terminal and an output terminal. The positive input terminal of the error amplifier unit 510 obtains an integrated signal, and the negative input terminal is connected to the first input terminal of the error amplifier circuit to obtain one of a reference signal and a feedback signal.

[0123] The integrated signal is generated based on the other of the reference signal and the feedback signal. Here, the integrated signal is provided by the compensation unit 520, which will be described in detail later.

[0124] The feedback signal is used to reflect the load power provided by the switching power supply where the switch control device is located to the load side. In some examples, the feedback signal may come from an inductance sensor as shown in the above examples. In other examples, the feedback signal is obtained based on the power supply voltage division output by the terminal where the switching power supply is connected to the load. In some other examples, the feedback signal is generated based on averaging the electrical signal in the inductance circuit in the power conversion unit.

[0125] The error amplification unit is used to amplify the error between the two signals received by the positive input terminal and the negative input terminal based on a preset gain and output an error amplification signal.

[0126] In some examples, the positive input terminal of the error amplifying unit is connected to the second input terminal of the error amplifying circuit through the compensation unit, and the negative input terminal of the error amplifying unit is connected to the first input terminal of the error amplifying circuit. In the case where the first input terminal receives a reference signal and the second input terminal receives a feedback signal, the negative input terminal of the error amplifying unit receives the reference signal, and the positive input terminal of the error amplifying unit receives an integrated signal obtained after the feedback signal is processed by the compensation unit.

[0127] In some other examples, the positive input terminal of the error amplifying unit is connected to the second input terminal of the error amplifying circuit through the compensation unit, and the negative input terminal of the error amplifying unit is connected to the first input terminal of the error amplifying circuit. In the case where the first input terminal receives a feedback signal and the second input terminal receives a reference signal, the negative input terminal of the error amplifying unit receives the feedback signal, and the positive input terminal of the error amplifying unit receives an integrated signal obtained after the reference signal is processed by the compensation unit.

[0128] Based on the connection mode provided in any of the above examples, the error amplification unit amplifies the error between the two signals received by the positive input terminal and the negative input terminal based on a preset gain and outputs an error amplification signal, and the error amplification signal is output through the output terminal of the error amplification circuit. For example, the error amplification signal is used as a reference signal for timing timeout and output to the switch on-off cycle detection module.

[0129] Here, in order to realize that the error amplification unit performs error amplification processing on the two received signals with a preset gain, the error amplification unit includes an error amplifier and a gain amplification module. Fig.12 As shown, the positive and negative input terminals of the error amplifier 5111 correspond to the positive and negative input terminals of the error amplification unit. The gain amplification module includes: a first resistive device (group) connected to the negative input terminal and the first input terminal, such as a resistor R1; and a second resistive device (group) arranged between the negative input terminal and the output terminal of the error amplifier, such as a resistor R2. The ratio of the second resistive device (group) to the first resistive device (group) is used to represent the gain of the error amplification unit.

[0130] In order to effectively solve the above-mentioned problem, the error amplifier circuit further includes a compensation unit 520, which receives the other signal of the reference signal and the feedback signal from the second input terminal 531 of the error amplifier circuit, and is connected to the positive input terminal of the error amplifier unit 510, and is used to compensate the feedback error amplification signal and integrate it with the signal obtained from the first input terminal to obtain the integrated signal. The integrated signal is used to compensate the error amplifier unit to weaken the biased power supply output by the switching power supply to the load side based on the change of the external circuit.

[0131] Here, the compensation unit 520 is used to compensate for the power supply deviation between the error amplified signal used to help the load side to stabilize the power supply and the actual load side power supply signal reflected by the feedback signal. The compensation processing method includes: offsetting the unmatched power supply deviation in the feedback signal, or compensating for the unmatched reference deviation in the reference signal.

[0132] Wherein, the external circuit includes a load circuit connected to the load side and / or an external AC power supply.

[0133] See also Fig.13 , which is a circuit structure diagram of the compensation unit in one embodiment. The compensation unit includes a gain compensation module 5201 and a signal integration module 5202.

[0134] The gain compensation module 5201 is connected to the output end of the error amplification unit, and is used to convert the error amplification signal fed back from the output end into a compensation signal based on the gain.

[0135] Here, in order to obtain the deviation between the feedback signal reflected by the error amplification signal and the reference signal, the gain compensation module reversely processes the error amplification signal based on the gain to obtain the compensation signal. Wherein, the gain compensation module at least includes a feedback compensation circuit, which is arranged on the line between the output end of the error amplification unit and the signal integration module based on the gain, and is used to divide the feedback error amplification signal based on the gain and output the compensation signal. For example, the feedback compensation circuit includes a third resistive device (group) connected between the positive input end and the output end of the error amplification unit, and a fourth resistive device (group) connected between the second input end and the positive input end of the error amplification unit. Wherein, the resistance ratio of the third resistive device (group) and the fourth resistive device (group) corresponds to the ratio of the second resistive device (group) and the first resistive device (group) in the above example, so that the compensation signal output by the feedback compensation circuit is a deviation signal between the feedback signal and the reference signal.

[0136] In order to reduce various defects such as feedback signal jitter and / or to reflect the average signal deviation, the gain compensation module further includes a buffer circuit. The buffer circuit is arranged on the feedback compensation circuit and is used to buffer the error amplification signal fed back in at least one switching cycle, so that the feedback compensation circuit outputs a compensation signal for reflecting the average value of the error amplification signal.

[0137] In some examples, the buffer circuit includes a buffer device (group). The buffer device includes a follower or a buffer gate (BUF). For example, the gain compensation module includes: a resistor R5 connected to the output end of the error amplification unit, a buffer gate connected to the resistor R5, a resistor R4 connected to the buffer gate and the positive input end of the error amplification unit, and a resistor R3 connected between the second input end and the positive input end of the error amplification unit. The feedback compensation circuit uses the parameters of the third resistive device (group), the fourth resistive device (group) and the buffer device to reflect the gain of the error amplification unit, and the output compensation signal V A According to the formula: Among them, A V Represents the gain of the error amplifier unit. Since the error amplification signal V COMPThe error signal between the signals received at the two input ends of the error amplifier unit is amplified by A V times the gain, so the compensation signal V A The error signal between the signals received by the two input terminals of the corresponding error amplifier unit.

[0138] In some other examples, the buffer circuit includes a filter device (group). The filter device includes a capacitor, which is used to provide an average signal of the error amplification signal within a number of switching cycles. For example, the gain compensation module includes: a resistor R5 connected to the output end of the error amplification unit, a capacitor with one plate connected to the resistor R5 and the other plate grounded, a buffer gate connected to the resistor R5, a resistor R4 connected to the buffer gate and the positive input end of the error amplification unit, and a resistor R3 connected between the second input end and the positive input end of the error amplification unit. To this end, the feedback compensation circuit uses the parameters of the third resistive device (group), the fourth resistive device (group), the capacitor, and the buffer device to reflect the gain of the error amplification unit, and the output compensation signal V A According to the formula: Among them, A V represents the gain of the error amplifier unit, Represents the average signal of the error amplified signal. The error signal between the signals received at the two input terminals of the error amplifier unit is amplified by the average value of A. V times the gain, so the compensation signal V A The average value of the error signal between the signals received by the two input terminals of the corresponding error amplification unit.

[0139] The compensation signal and the signal received by the second input terminal of the error amplifying circuit are respectively input to two input terminals of the signal integration module for integration processing, and the obtained integrated signal is transmitted to the error amplifying unit.

[0140] In combination with the aforementioned example, when the first input terminal of the error amplifier circuit receives a reference signal and the second input terminal receives a feedback signal, the signal integration module includes a subtraction integration circuit connected between the second input terminal and the positive input terminal of the error amplifier unit, and used to subtract the compensation signal from the acquired feedback signal to obtain an integration signal. The subtraction integration circuit includes a subtractor, a buffer circuit, etc.

[0141] See also Fig.14 , which is a circuit structure diagram of an error amplifier circuit in one embodiment, wherein the subtractor in the subtraction integration circuit 6202 is disposed between the fourth resistive device (group) 6201a in the gain compensation module and the positive input terminal of the error amplifier unit 5111.FB The compensation signal is input to one input terminal of the subtraction integration circuit 6202 through the fourth resistive device (group) 6201a, and the compensation signal is input to the other input terminal of the subtraction integration circuit through a buffer circuit and the third resistive device (group) 6201b. The subtraction integration circuit 6202 performs difference processing on the two signals to obtain an integrated signal and outputs it to the positive input terminal of the error amplifier unit 5111. The error amplifier unit 5111 converts the integrated signal at the positive input terminal and the reference signal V at the negative input terminal into a differential signal. ref1 Perform error amplification processing to output the error amplified signal V COMP Since the signal deviation between the feedback signal and the reference signal is offset by the compensation unit, the error amplified signal is not interfered by the feedback signal, thereby effectively eliminating the aforementioned defect caused by the reference signal being a fixed signal.

[0142] In the case where the second input terminal of the error amplifier circuit receives a reference signal and the first input terminal receives a feedback signal, the signal integration module includes an addition integration circuit connected between the second input terminal and the positive input terminal of the error amplifier unit, and is used to subtract the compensation signal from the acquired reference signal to obtain an integration signal. The subtraction integration circuit includes a wire connecting the third resistive device (group) and the fourth resistive device (group), a buffer circuit, etc.

[0143] See also Fig.15 , which is a circuit structure diagram of an error amplifier circuit in one embodiment, the line between the fourth resistive device (group) 6201a in the gain compensation module and the positive input terminal of the error amplifier unit 5111 is connected to the line where the third resistive device (group) 6201b is located; or the line between the fourth resistive device (group) 6201a in the gain compensation module and the positive input terminal of the error amplifier unit 5111 is connected to the third resistive device (group) 6201b through an adder. Among them, the reference signal V ref The integrated signal is combined with the compensation signal through a buffer circuit and the fourth resistive device (group) through the conductive line (or adder) 7202 to form an integrated signal, and is output to the positive input terminal of the error amplifier unit 5111. The error amplifier unit 5111 combines the integrated signal at the positive input terminal and the feedback signal V at the negative input terminal. FB The error amplification process is performed to output the error amplified signal. Also, since the compensation unit is used to offset the signal deviation between the feedback signal and the reference signal, the error amplified signal is not interfered by the feedback signal, thereby effectively eliminating the aforementioned defect caused by the reference signal being a fixed signal.

[0144] In combination with the example in the aforementioned switching power supply and the example in the aforementioned error amplifier circuit, the present application also provides a method including: Figure 11-15The switching power supply of the error amplifier circuit described in any example, wherein the switching power supply comprises: a rectifying unit, a switching unit, a power conversion unit and a switch control device.

[0145] The rectifier unit, the switch unit and the power conversion unit are respectively Figure 1 The circuit structures and working processes of the rectifying unit, the switching unit and the power conversion unit in the switching power supply shown are the same or similar and will not be described in detail here.

[0146] For example, the rectifier unit includes a full-wave rectifier bridge. The switch unit includes a power tube. The power conversion unit includes an inductor circuit and an energy storage circuit; wherein the inductor circuit includes: a primary winding connected to the power supply bus and the switch control device; a secondary winding coupled to the primary winding and connected to the power supply bus and providing a power supply terminal on the load side; and the energy storage circuit is connected between the power supply bus and the power supply terminal.

[0147] The switch control device comprises: a load feedback unit, a conduction detection unit, a disconnection detection unit, and a logic control unit. Figure 3 The circuit structures and working processes of the load feedback unit, the disconnection detection unit and the logic control unit in the switch control device shown are the same or similar, and will not be described in detail here.

[0148] The conduction detection unit includes Fig.11 According to the circuit structure inside the error amplifier circuit, its first input terminal can be connected to the load feedback unit, and the second input terminal receives the reference signal; or, the first input terminal of the error amplifier circuit receives the reference signal, and the second input terminal is connected to the load feedback unit.

[0149] The circuit structure inside the error amplifier circuit is as follows Fig.11 As shown in the example, the first input end of the error amplifier circuit receives a reference signal, the second input end is connected to the load feedback unit, the output end of the error amplifier circuit is connected to the switch on-off cycle detection module in the conduction detection unit, and the switch on-off cycle detection module uses the error amplification signal output by the error amplifier circuit as a timing reference signal to time the conduction duration of the switch unit. The switch on-off cycle detection module outputs a first conduction detection signal when the timing times out. The switch on-off cycle detection module can adjust the on-off cycle of the switch unit by adjusting the conduction duration.

[0150] The conduction detection unit may also include: a demagnetization detection module, and / or a CCM mode switch on-off cycle timing module according to design requirements. The demagnetization detection module is used to output a second conduction detection signal when the inductor circuit in the power conversion unit is demagnetized. The CCM mode switch on-off cycle timing module is used to perform CCM mode timing when the switch unit is disconnected, and output a third conduction detection signal when the timing times out.

[0151] The working process of the switching power supply in different modes is as mentioned above Figure 7 , 8 , 10 and the corresponding description examples will not be described in detail here.

[0152] See also Fig.16 , which is a flow chart of the method for generating the error amplification signal of the present application. The generation method is also used in the error amplification circuit.

[0153] In step S110, the error amplifier circuit obtains a reference signal and a feedback signal; wherein the feedback signal is used to reflect the load power provided by the switch power supply where the switch control device is located to the load side.

[0154] In step S120, the error amplifier circuit amplifies the error between an integrated signal and one of the reference signal and the feedback signal based on a preset gain, and outputs an error amplified signal. The integrated signal is obtained by integrating the compensated error amplified signal with the other of the reference signal and the feedback signal; the integrated signal is used to compensate the error amplified signal to weaken the power supply with deviation output by the switching power supply to the load side based on the change of the external circuit.

[0155] Here, the error amplifier circuit obtains the feedback signal by connecting to a load feedback unit. The error amplifier circuit includes a set gain, and converts the feedback error amplifier signal into a compensation signal based on the gain.

[0156] The error amplifier circuit buffers the error amplification signal fed back by the switching power supply in at least one switching cycle to output a compensation signal reflecting a mean value signal of the error amplification signal.

[0157] The error amplifier circuit integrates the compensation signal with one of the reference signal and the feedback signal to reduce the deviation, thereby obtaining the integrated signal. The error amplifier circuit performs error amplification processing on the integrated signal and the other of the reference signal and the feedback signal to output the error amplified signal.

[0158] In some examples, reference Fig.15As shown, the error amplifier circuit adds the acquired reference signal and the compensation signal to obtain the integrated signal based on the differential method of the integrated signal and the reference signal.

[0159] In other examples, reference Fig.14 As shown, the error amplifier circuit subtracts the compensation signal from the acquired feedback signal based on the difference between the integrated signal and the feedback signal to obtain the integrated signal.

[0160] See also Fig.17 , which is a flow chart of a control method of a switch control device of the present application, wherein the control method can be executed by a switch control device. The switch control device changes an electrical signal in a power conversion unit connected to a power supply bus so that the power conversion unit provides stable power to a load.

[0161] In step S210, the switch control device obtains a feedback signal reflecting a load-side power supply signal, and samples an induction signal in the power conversion unit.

[0162] In step S220 , the switch control device executes the steps in the method for generating the error amplified signal as described in steps S110 - S120 .

[0163] In step S230, the switch control device performs conduction detection based on the error amplified signal, and controls the switch unit in the switch control device to be turned on according to the detection result; or detects the sampling signal, and controls the switch unit in the switch control device to be turned off based on the detection result.

[0164] The above steps can be performed based on the above examples of the switch control device, and will not be described in detail here.

[0165] The switch control device provided in the present application adjusts the on-off timing of the switch unit based on the feedback signal used to reflect the power supply on the load side, so that the switch power supply to which it belongs can work stably in multiple modes, especially in multiple modes including the QR mode, thereby realizing adaptive and stable power supply to the changing load. The error amplifier circuit provided in the present application effectively eliminates the mismatch relationship between the actual feedback signal and the error amplification signal required for the stable operation of the switch control device by compensating the error signal between the feedback signal and the reference signal, and realizes that the voltage deviation between the feedback signal and the reference signal is independent of the stable interval of the error amplification signal, thereby effectively eliminating the mismatch relationship.

[0166] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. An error amplifier circuit, applied to a switch control device, characterized in that: include: The error amplifier unit has a positive input terminal, a negative input terminal and an output terminal; wherein the positive input terminal obtains an integrated signal, and the negative input terminal obtains one of a reference signal and a feedback signal from the first input terminal of the error amplifier circuit; wherein the feedback signal is used to reflect the load power provided by the switch power supply where the switch control device is located to the load side; The error amplification unit is used to amplify the error between the two signals received by the positive input terminal and the negative input terminal based on a preset gain and output an error amplification signal; a compensation unit, receiving the other of the reference signal and the feedback signal from the second input terminal of the error amplifying circuit and connected to the positive input terminal of the error amplifying unit, for compensating the feedback error amplifying signal and integrating it with the signal obtained from the first input terminal to obtain the integrated signal; The integrated signal is used to compensate the error amplification unit to weaken the power supply with deviation output by the switching power supply to the load side based on the change of the external circuit.

2. The error amplifier circuit according to claim 1, characterized in that: The compensation unit comprises: A gain compensation module, connected to the output end of the error amplification unit, for converting the error amplification signal fed back from the output end into a compensation signal based on the gain; A signal integration module is connected to the second input terminal of the error amplifier circuit, the positive input terminal of the error amplifier unit, and the gain compensation module, and is used to integrate the compensation signal with the reference signal or feedback signal obtained from the second input terminal so as to reduce the deviation of the error amplifier unit and obtain the integrated signal.

3. The error amplifier circuit according to claim 2, characterized in that: The gain compensation module comprises: The feedback compensation circuit is arranged on a line between the output end of the error amplification unit and the signal integration module based on the gain, and is used to divide the feedback error amplification signal based on the gain and output the compensation signal.

4. The error amplifier circuit according to claim 3, characterized in that: The gain compensation module further includes: The buffer circuit is arranged on the feedback compensation circuit and is used to buffer the error amplification signal fed back in at least one switching cycle so that the feedback compensation circuit outputs a compensation signal reflecting the average value of the error amplification signal.

5. The error amplifier circuit according to claim 2, characterized in that: The signal integration module comprises: an adding integration circuit, connected between the second input terminal and the positive input terminal of the error amplifying unit, for adding the acquired reference signal and the compensation signal to obtain an integrated signal; or The subtraction integration circuit is connected between the second input terminal and the positive input terminal of the error amplification unit, and is used for subtracting the compensation signal from the acquired feedback signal to obtain an integration signal.

6. The error amplifier circuit according to claim 1, characterized in that: The error amplification unit comprises: an error amplifier, outputting the error amplified signal based on an error signal between two signals provided by the positive input terminal and the negative input terminal; The gain amplification module is connected between the negative input terminal and the output terminal of the error amplifier and is used to determine the gain.

7. A switch control device, which changes an electrical signal in a power conversion unit connected to a power supply bus so that the power conversion unit provides stable power to a load, characterized in that: include: A load feedback unit, coupled to the power conversion unit, for generating and outputting a feedback signal for reflecting a load-side power supply signal; A switch unit, arranged on the power supply bus and connected to the power conversion unit; A sampling unit, coupled to the power conversion unit, to obtain a sampling signal for reflecting a current peak value in an inductor circuit in the power conversion unit; a conduction detection unit connected to the error amplifier circuit, comprising the error amplifier circuit as claimed in any one of claims 1 to 6; wherein the first input terminal and the second input terminal of the error amplifier circuit receive a reference signal and the feedback signal respectively; the conduction detection unit performs conduction detection based on the error amplification signal, and outputs a first conduction detection signal according to the detection result; a disconnection detection unit, coupled to the sampling unit, configured to detect the sampling signal based on the feedback signal and output a disconnection detection signal based on the detection result; A logic control unit is connected to the conduction detection unit and the disconnection detection unit, and is used to control the switch unit to be turned on / off based on the control logic of the disconnection detection signal and the first conduction detection signal.

8. The switch control device according to claim 7, characterized in that: The load feedback unit comprises: An inductor sensor coupled to the inductor in the power conversion unit for generating an induction signal for outputting power to a load side; The voltage divider circuit is arranged on a line between the inductance sensor and a reference voltage terminal, and is used for outputting the feedback signal based on the electrical signal output by the inductance sensor.

9. The switch control device according to claim 7, characterized in that: The conduction detection unit further detects the induction signal of the power conversion unit and outputs a second conduction detection signal based on the detection result; The logic control unit controls the switch unit to be turned on / off based on the control logic of the disconnection detection signal, the first conduction detection signal, and the second conduction detection signal.

10. A switching power supply, characterized in that: include: The rectifier unit is connected to an external AC power source and is used to rectify the AC power and output it to the power supply bus; A switch unit, connected to the power supply bus and controlled to be turned on / off; A power conversion unit connected to the switch unit, used to provide stable power supply to the load by means of the intermittent electrical signal generated by the switch unit, wherein the power conversion unit includes an energy storage circuit and an inductor circuit used to convert the intermittent electrical signal into power supply for the load and energy storage for the energy storage circuit; A switch control device as claimed in any one of claims 7 to 9.

11. The switching power supply according to claim 10, characterized in that: The inductor circuit comprises: A primary winding connected to the power supply bus and the switch control device; A secondary winding coupled to the primary winding and connected to the power supply bus and providing a power supply terminal on the load side; The energy storage circuit is connected between the power supply bus and the power supply terminal.

12. The switching power supply according to claim 11, characterized in that: The load feedback unit in the switch control device is coupled to the primary winding or the secondary winding.

13. The switching power supply according to claim 10, characterized in that: The inductance circuit comprises: an inductor connected to the power supply bus and the switch control device; and the energy storage circuit connected between the current output end of the inductor and the power supply bus.

14. The switching power supply according to claim 13, characterized in that: The load feedback unit in the switch control device is coupled to the inductor or to a load output terminal on the load side of the power conversion unit.

15. A method for generating an error amplification signal, characterized in that: include: Acquire a reference signal and a feedback signal; wherein the feedback signal is used to reflect the load power provided by the switch power supply where the switch control device is located to the load side; amplifying an error between an integrated signal and one of the reference signal and the feedback signal based on a preset gain, and outputting an error amplified signal; The integrated signal is obtained by integrating the compensated error amplified signal with the other of the reference signal and the feedback signal; The integrated signal is used to compensate the error amplification signal to weaken the power supply with deviation output by the switching power supply to the load side based on the change of the external circuit.

16. The method for generating an error amplified signal according to claim 15, characterized in that: The step of integrating the compensated error amplified signal with the other of the reference signal and the feedback signal comprises: converting the fed-back error amplified signal into a compensation signal based on the gain; The compensation signal is integrated with the other signal of the reference signal and the feedback signal to reduce the deviation, thereby obtaining the integrated signal.

17. The method for generating an error amplified signal according to claim 16, characterized in that: The step of converting the fed-back error amplification signal into a compensation signal based on the gain includes: buffering the error amplification signal fed back by the switching power supply in at least one switching cycle to output a compensation signal reflecting the mean value signal of the error amplification signal.

18. The method for generating an error amplified signal according to claim 16, characterized in that: The step of integrating the compensation signal with the other of the reference signal and the feedback signal for bias reduction comprises: Based on the difference between the integrated signal and the reference signal, the acquired reference signal and the compensation signal are added to obtain the integrated signal; or Based on the difference between the integrated signal and the feedback signal, the compensation signal is subtracted from the acquired feedback signal to obtain the integrated signal.

19. A control method for a switch control device, wherein: The switch control device changes the electrical signal in the power conversion unit connected to the power supply bus so that the power conversion unit provides stable power supply to the load, and the control method includes: Acquire a feedback signal reflecting a load-side power supply signal and a sampling signal reflecting a current peak value in an inductive circuit in the power conversion unit, and sample an inductive signal in the power conversion unit; The method for generating an error amplification signal as claimed in any one of claims 15 to 18; Performing conduction detection based on the error amplified signal, and controlling the switch unit in the switch control device to conduct according to the detection result; The sampling signal is detected, and based on the detection result, the switch unit in the switch control device is controlled to be disconnected.

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