Switching control circuits, their switching control methods, and switching power supplies

Abstract

This invention proposes a switch control circuit, a switch control method, and a switching power supply. The switch control circuit controls the main switching transistor in the switching power supply and includes a feedback signal processing circuit, a signal conversion circuit, and a drive signal generation circuit. The feedback signal processing circuit receives a feedback signal characterizing the output signal of the switching power supply and generates a low-voltage side signal based on the feedback signal. The signal conversion circuit is coupled to the feedback signal processing circuit and generates a high-voltage side signal based on the low-voltage side signal; the high-voltage side signal is an analog signal. The input terminal of the drive signal generation circuit is coupled to the second terminal of the signal conversion circuit, and the drive signal generation circuit generates a switch control signal based on the high-voltage side signal. This invention provides a switch control circuit, a switch control method, and a switching power supply that, through direct output sampling, can achieve high-precision constant voltage control and / or constant current control.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power electronics, and relates to a switching control technology, in particular to a switching control circuit, a switching control method thereof and a switching power supply. BACKGROUND

[0002] Switching power supply is a major product of electronic power supply. It is widely used in most electronic devices such as consumer electronics and communication equipment due to its light weight, miniaturization, wide input voltage range, high power density / conversion efficiency, low standby power consumption and many other advantages.

[0003] The buck switching power supply is a commonly used topology circuit in switching power supplies. According to the setting position of the main switch tube in the switching power supply, it can be divided into high-voltage side buck switching power supply and low-voltage side buck switching power supply. Among them, the high-voltage side buck switching power supply includes a main switch tube, an inductor, an output capacitor and a diode. The first end of the main switch tube is coupled to the bus voltage, the first end of the inductor is coupled to the second end of the main switch tube, the first end of the output capacitor is coupled to the second end of the inductor, and the second end of the output capacitor is coupled to the input ground. The anode of the diode is coupled to the second end of the output capacitor, and the cathode of the diode is coupled to the first end of the inductor. In order to realize the constant current control of the buck switching power supply, a sampling resistor is generally arranged between the diode and the inductor to detect the current flowing through the inductor. However, the constant current control precision of the prior art scheme is not high, and in some application scenarios, higher precision of the output voltage and / or output current of the switching power supply is required.

[0004] Therefore, it is necessary to provide a new structure or control method to solve at least part of the above problems. SUMMARY

[0005] In view of one or more problems in the prior art, the present application provides a switching control circuit, a switching control method thereof and a switching power supply.

[0006] According to one aspect of the present application, a switching control circuit is disclosed for controlling a main switch tube in a switching power supply, the switching power supply being a high-voltage side buck switching power supply, the switching control circuit comprising:

[0007] a feedback signal processing circuit, an input end of which receives a feedback signal representing an output signal of the switching power supply, for generating a low-voltage side signal according to the feedback signal; the feedback signal being a signal with the input ground as the reference ground;

[0008] a signal conversion circuit, a first end of which is coupled to an output end of the feedback signal processing circuit, for generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal being an analog signal; and

[0009] The driving signal generating circuit is coupled to the second end of the signal converting circuit, and is used to generate a switch control signal according to the high-voltage side signal to control the main switch tube.

[0010] In one embodiment, the feedback signal processing circuit generates a low-voltage side signal according to the feedback signal, and the low-voltage side signal is a current signal.

[0011] In one embodiment, the feedback signal processing circuit comprises a pulse width generating circuit, which is coupled to the feedback signal end to receive the feedback signal, and is used to generate a pulse width signal according to the feedback signal, and the duty cycle of the pulse width signal is proportional to the feedback signal.

[0012] In one embodiment, the feedback signal processing circuit comprises a first transconductance operational amplifier circuit, which is coupled to the feedback signal end to receive the feedback signal, and is coupled to the first reference signal end to receive the first reference signal, and outputs the low-voltage side signal.

[0013] In one embodiment, the signal converting circuit comprises:

[0014] a field effect tube, whose source is coupled to the feedback signal processing circuit, and whose control end is coupled to the first voltage; and

[0015] a compensation signal generating circuit, which is coupled to the drain of the field effect tube, and outputs the compensation signal according to the first current, and the high-voltage side signal is the compensation signal, and the first current is the current flowing through the drain of the field effect tube.

[0016] In one embodiment, the compensation signal generating circuit comprises:

[0017] a current mirror, whose first end is coupled to the drain of the field effect tube, and whose second end outputs a current adjusting signal;

[0018] a third resistor, whose first end is coupled to the second end of the current mirror, and whose second end is coupled to the ground; and

[0019] an error amplifier circuit, whose first end is coupled to the second end of the current mirror, and whose second end is coupled to the second reference signal end to obtain the second reference signal, and whose output end outputs the compensation signal.

[0020] In one embodiment, the compensation signal generating circuit comprises:

[0021] a current mirror, whose first end is coupled to the drain of the field effect tube;

[0022] a third resistor, whose first end is coupled to the second end of the current mirror;

[0023] a fourth resistor, whose first end is coupled to the second end of the current mirror; and

[0024] a second capacitor having a first end coupled to the second end of the fourth resistor and a second end coupled to the second end of the third resistor, the first end of the second capacitor outputting the compensation signal.

[0025] In one embodiment, the compensation signal generation circuit comprises:

[0026] a current mirror having a first end coupled to the drain of the field effect transistor and a second end outputting the compensation signal; and

[0027] a third resistor having a first end coupled to the second end of the current mirror and a second end coupled to ground.

[0028] In one embodiment, the compensation signal generation circuit comprises:

[0029] a fifth resistor having a first end coupled to the second voltage and a second end coupled to the drain of the field effect transistor;

[0030] a first transconductance operational amplifier circuit having a first input end coupled to the first end of the fifth resistor and a second input end coupled to the second end of the fifth resistor;

[0031] a second capacitor having a first end coupled to the output end of the first transconductance operational amplifier circuit and a second end coupled to ground;

[0032] a second transconductance operational amplifier circuit having a first input end coupled to the first end of the second capacitor and a second end coupled to the third reference signal end to obtain the third reference signal; and

[0033] a third capacitor having a first end coupled to the output end of the second transconductance operational amplifier circuit and a second end coupled to ground, the first end of the third capacitor outputting the compensation signal.

[0034] In one embodiment, the field effect transistor is an N-type junction field effect transistor or an N-type metal oxide semiconductor field effect transistor.

[0035] According to another aspect of the present application, a switching power supply is disclosed, the switching power supply being a high-voltage-side step-down switching power supply, the switching power supply comprising the switching control circuit as claimed in any one of the above.

[0036] According to yet another aspect of the present application, a switching control method is disclosed, the switching control method being used to control a switching control circuit, the switching control method comprising:

[0037] receiving a feedback signal representing an output signal of the switching power supply, the feedback signal being a signal having a reference ground as an input ground;

[0038] generating a low-voltage-side signal according to the feedback signal; the low-voltage-side signal being an analog signal; and

[0039] generating a switching control signal according to the high-voltage-side signal to control a main switch tube.

[0040] The application provides a switching control circuit, a switching control method and a switching power supply. The switching control circuit is used for controlling a main switch tube in the switching power supply. The switching power supply is a high-voltage side step-down switching power supply. The switching control circuit comprises a feedback signal processing circuit, a signal conversion circuit and a driving signal generation circuit. An input end of the feedback signal processing circuit receives a feedback signal representing an output signal of the switching power supply. The feedback signal processing circuit is used for generating a low-voltage side signal according to the feedback signal. The feedback signal is a signal with an input ground. A first end of the signal conversion circuit is coupled with an output end of the feedback signal processing circuit. The signal conversion circuit is used for generating a high-voltage side signal according to the low-voltage side signal. The high-voltage side signal is an analog signal. An input end of the driving signal generation circuit is coupled with a second end of the signal conversion circuit. An output end of the driving signal generation circuit is used for coupling with the main switch tube. The driving signal generation circuit is used for generating a switching control signal according to the high-voltage side signal to control the main switch tube. The switching control circuit, the switching control method and the switching power supply can realize high-precision constant voltage control and / or constant current control by directly sampling the output signal. In addition, the system working frequency of the switching power supply is not limited by the response speed of the signal conversion circuit. The system can realize high-frequency working, improve the system power density and reduce the system size. BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and are included to provide a further understanding of the application, and are included as a part of this specification illustrate embodiments of the application and are included to provide a further understanding of the application. In the drawings:

[0042] Figure 1 Fig. 1 shows a circuit structure schematic diagram of a switching power supply according to an embodiment of the application;

[0043] Figure 2 Fig. 2 shows a circuit structure schematic diagram of a signal conversion circuit according to an embodiment of the application;

[0044] Figure 3 Fig. 3 shows a circuit structure schematic diagram of a signal conversion circuit according to another embodiment of the application;

[0045] Figure 4 Fig. 4 shows a circuit structure schematic diagram of a switching control circuit according to an embodiment of the application;

[0046] Figure 5 Fig. 5 shows a circuit structure schematic diagram of a switching control circuit according to another embodiment of the application;

[0047] Figure 6 Fig. 6 shows a circuit structure schematic diagram of a switching control circuit according to still another embodiment of the application;

[0048] Figure 7A schematic diagram of the circuit structure of a switch control circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0049] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0050] The description in this section pertains to only a few typical embodiments, and the present invention is not limited to the scope of the embodiments described. Combinations of different embodiments, substitution of some technical features in different embodiments, and substitution of similar or identical prior art with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0051] The terms "coupled" or "connected" in this specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a connection through an electrically conductive medium like a conductor, which may contain parasitic inductance or capacitance. It can also be a connection through intermediate circuits or components described in the embodiments of this specification. Indirect connections may also include connections through other active or passive devices that achieve the same or similar functions, such as connections through switches, signal amplification circuits, follower circuits, or other circuits or components. "A plurality of" or "more" indicates two or more. Furthermore, in this invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship or order between these technical features.

[0052] In such Figure 1 As shown, an embodiment of the present invention discloses a switching power supply, which is a high-side step-down switching power supply. The switching power supply includes a main switching transistor Q1, an inductor L1, a first capacitor C1, and a first diode D1. The first terminal of the main switching transistor Q1 is coupled to the bus voltage, the first terminal of the inductor L1 is coupled to the second terminal of the main switching transistor Q1, the first terminal of the first capacitor C1 is coupled to the second terminal of the inductor L1, the anode of the first diode D1 is coupled to the second terminal of the first capacitor C1, and the cathode of the first diode D1 is coupled to the second terminal of the main switching transistor Q1. A switching control circuit 10 is used to control the main switching transistor in the switching power supply. The switching control circuit 10 includes a feedback signal processing circuit 110, a signal conversion circuit 120, and a drive signal generation circuit 130. In one embodiment, the switching control circuit 10 includes the main switching transistor Q1. In another embodiment, the main switching transistor Q1 is disposed outside the switching control circuit 10. Figure 1As shown, the input terminal of the feedback signal processing circuit 110 receives a feedback signal characterizing the output signal of the switching power supply. The feedback signal processing circuit generates a low-voltage side signal based on the feedback signal. The output signal of the switching power supply can be its output voltage and / or output current. The feedback signal is a signal with its reference ground as the input ground. The feedback signal processing circuit 110 generates a low-voltage side signal with its reference ground as the input ground based on the feedback signal. Figure 1 In one embodiment shown, the switching power supply further includes a first resistor R1 and a second resistor R2. The first end of the second resistor R2 is coupled to the first end of the first capacitor C1, and the first end of the first resistor R1 is coupled to the second end of the second resistor R2. The second end of the first resistor R1 is coupled to the input ground. Furthermore, the first end of the first resistor R1 is coupled to the feedback signal terminal of the switch control circuit 10 to provide a feedback signal. The first end of the signal conversion circuit 120 is coupled to the output terminal of the feedback signal processing circuit 110. The signal conversion circuit 120 is used to generate a high-voltage side signal based on the low-voltage side signal. The low-voltage side signal is an analog signal, and the high-voltage side signal is also an analog signal. The high-voltage side signal is a floating ground-based signal, and a switch control signal can be generated based on the high-voltage side signal to control the state of the main switch transistor. The input terminal of the drive signal generation circuit 130 is coupled to the second end of the signal conversion circuit 120, and the output terminal of the drive signal generation circuit 130 is used to couple to the main switch transistor Q1. The drive signal generation circuit 130 is used to generate a switch control signal based on the high-voltage side signal to control the main switch transistor. Based on the switching control circuit of this invention, high-precision constant voltage control and / or constant current control can be achieved through direct output sampling. Furthermore, since the signal conversion circuit does not directly transmit the turn-on and turn-off signals of the main switching transistor, the system operating frequency of the switching power supply is not limited by the response speed of the signal conversion circuit, enabling high-frequency operation, increasing system power density, and reducing system size.

[0053] In another embodiment, the switching power supply includes a main switching transistor Q1, an inductor L1, a first capacitor C1, a first diode D1, and a sampling resistor. The first terminal of the main switching transistor Q1 is coupled to the bus voltage, the first terminal of the inductor L1 is coupled to the second terminal of the main switching transistor Q1, the first terminal of the first capacitor C1 is coupled to the second terminal of the inductor L1, the first terminal of the sampling resistor is coupled to the second terminal of the first capacitor C1, the anode of the first diode D1 is coupled to the second terminal of the sampling resistor, and the cathode of the first diode D1 is coupled to the second terminal of the main switching transistor Q1. The feedback signal terminal of the switching control circuit is coupled to the first terminal of the sampling resistor to obtain a feedback signal characterizing the output current of the switching power supply, thereby achieving constant current control of the switching power supply. By connecting the sampling resistor in series in the output circuit, full integration of the output current is achieved, resulting in higher constant current control accuracy.

[0054] In an embodiment of the present application, the feedback signal represents the output voltage of the switching power supply, and the switching control circuit controls the output voltage of the switching power supply according to the feedback signal, so as to realize constant voltage output. In another embodiment of the present application, the feedback signal represents the output current of the switching power supply, and the switching control circuit controls the output current of the switching power supply according to the feedback signal, so as to realize constant current output. In yet another embodiment of the present application, the feedback signal represents the output voltage and the output current of the switching power supply, and the output voltage and the output current of the switching power supply are respectively represented by time-division sampling, and the switching control circuit controls the output voltage and the output current of the switching power supply according to the feedback signal. In the present application, real-time feedback is realized by directly sampling the output signal, so as to realize excellent output dynamic response.

[0055] In an embodiment of the present application, the feedback signal processing circuit comprises a first transconductance operational amplifier circuit, a first input end of the first transconductance operational amplifier circuit is coupled to the feedback signal end to receive the feedback signal, a second input end of the first transconductance operational amplifier circuit is coupled to the first reference signal end to receive the first reference signal, and an output end of the first transconductance operational amplifier circuit outputs the low-voltage side signal. The signal conversion circuit comprises a field effect transistor and a compensation signal generation circuit, a source electrode of the field effect transistor is coupled to the output end of the feedback signal processing circuit, a control end of the field effect transistor is coupled to the first voltage, an input end of the compensation signal generation circuit is coupled to a drain electrode of the field effect transistor, and an output end of the compensation signal generation circuit outputs the compensation signal. The compensation signal generation circuit is used for generating the compensation signal according to the first current, the high-voltage side signal is the compensation signal, and the first current is the current flowing through the drain electrode of the field effect transistor. As shown in an embodiment, Figure 2 As shown in an embodiment, the signal conversion circuit 121 comprises an N-type junction field effect transistor and a compensation signal generation circuit. A source electrode of the N-type junction field effect transistor is coupled to the feedback signal processing circuit, and a control end of the N-type junction field effect transistor is coupled to the ground. The N-type junction field effect transistor can be realized by general high-voltage process, without using special process, so as to reduce the chip cost. The compensation signal generation circuit comprises a current mirror and a third resistor R3, a first end of the current mirror is coupled to a drain electrode of the N-type junction field effect transistor, a second end of the current mirror is coupled to a first end of the third resistor R3, a second end of the third resistor R3 is coupled to the ground, and the second end of the current mirror outputs the compensation signal COMPH. The compensation signal generation circuit further comprises a second capacitor, a first end of the second capacitor is coupled to the first end of the third resistor, and a second end of the second capacitor is coupled to the second end of the third resistor. The switching control circuit generates the switching control signal according to the compensation signal COMPH to control the switching state of the main switch tube. In a specific embodiment, the drive signal generation circuit comprises a comparator, a first end of the comparator is coupled to the second end of the current mirror to obtain the compensation signal COMPH, a second end of the comparator is coupled to the sawtooth wave generation circuit, and an output end of the comparator is coupled to the control end of the main switch tube Q1.

[0056] In another embodiment of the present application, as Figure 3As shown, the signal conversion circuit 122 comprises an N-type metal oxide semiconductor field effect transistor (NMOS transistor for short) and a compensation signal generation circuit, the drain of the NMOS transistor is coupled to the compensation signal generation circuit, the source of the NMOS transistor is coupled to the feedback signal processing circuit, and the control end of the NMOS transistor is coupled to the first voltage Vb.

[0057] In an embodiment of the present application, as shown in Figure 4 As shown, the switch control circuit comprises a feedback signal processing circuit 113, a signal conversion circuit 123, and a driving signal generation circuit (not shown in the figure). The feedback signal processing circuit 113 comprises a transconductance conversion circuit, the input end of the transconductance conversion circuit is coupled to the feedback signal, and the transconductance conversion circuit is used to convert the feedback signal as a voltage signal into a low-voltage side signal as a current signal. The signal conversion circuit comprises an N-type junction field effect transistor of a high-voltage type and a compensation signal generation circuit, and the signal conversion circuit converts the low-voltage side signal into a high-voltage side signal. The compensation signal generation circuit comprises a current mirror, a third resistor R3, and an error amplification circuit, the first end of the current mirror is coupled to the drain of the N-type junction field effect transistor, and the current mirror outputs a current adjustment signal FBH according to the high-voltage side signal. The first end of the third resistor R3 is coupled to the second end of the current mirror, and the second end of the third resistor R3 is coupled to the ground. The first end of the error amplification circuit is coupled to the second end of the current mirror, the second end of the error amplification circuit is coupled to the second reference signal end to obtain the second reference signal Vref2, and the output end of the error amplification circuit outputs the compensation signal COMPH. The switch control circuit generates a switch control signal according to the compensation signal COMP to control the switching state of the switch tube. Since the low-voltage side signal and the compensation signal are not common ground signals, the low-voltage side signal is a signal with a real ground as a reference ground, and the compensation signal is a signal with a floating ground as a reference ground, so the low-voltage side signal cannot be directly used to control the switching action of the main switch tube. Through the signal conversion of the switch control circuit, the circuit of the high-voltage side can timely obtain the feedback signal, thereby performing corresponding output control.

[0058] In another embodiment of the present application, as shown in Figure 5 As shown, the switch control circuit comprises a feedback signal processing circuit 114, a signal conversion circuit 124, and a driving signal generation circuit (not shown in the figure). The signal conversion circuit comprises a field effect transistor Q4 and a compensation signal generation circuit, and specifically, the field effect transistor Q4 is an NMOS transistor of a high-voltage type.

[0059] In an embodiment of the present application, as shown in Figure 6As shown, the switch control circuit includes a feedback signal processing circuit 115, a signal conversion circuit 125 and a driving signal generating circuit (not shown). The feedback signal processing circuit 115 includes a first trans-impedance operational amplifier circuit and a pulse width generating circuit. A first input terminal of the first trans-impedance operational amplifier circuit is coupled to a feedback signal terminal for receiving a feedback signal, a second input terminal of the first trans-impedance operational amplifier circuit is coupled to a first reference signal terminal for receiving a first reference signal Vref1, and an output terminal of the first trans-impedance operational amplifier circuit outputs a low voltage side signal COMPL. An input terminal of the pulse width generating circuit is coupled to the output terminal of the first trans-impedance operational amplifier circuit, and the pulse width generating circuit is configured to generate a pulse width signal according to the feedback signal, and a duty cycle of the pulse width signal is proportional to the feedback signal. The signal conversion circuit includes a field effect transistor Q4 and a compensation signal generating circuit, a drain of the field effect transistor Q4 is coupled to an input terminal of the compensation signal generating circuit, and a source of the field effect transistor Q4 is coupled to an output terminal of the feedback signal processing circuit 115. The compensation signal generating circuit includes a current mirror, a third resistor R3, a fourth resistor R4 and a second capacitor C2. A first terminal of the current mirror is coupled to the drain of the field effect transistor Q4, a first terminal of the third resistor R3 is coupled to a second terminal of the current mirror, a second terminal of the third resistor R3 is coupled to a floating ground, a first terminal of the fourth resistor R4 is coupled to the second terminal of the current mirror. A first terminal of the second capacitor C2 is coupled to a second terminal of the fourth resistor R4, a second terminal of the second capacitor C2 is coupled to the second terminal of the third resistor R3, and a first terminal of the second capacitor C2 outputs a compensation signal COMPH. The switch control circuit converts the feedback signal of the low voltage side into the pulse width signal, and a duty cycle of the pulse width signal is proportional to the feedback signal. The signal conversion circuit processes the pulse width signal to obtain a high voltage side signal from the driving signal generating circuit, and the high voltage side signal is proportional to the duty cycle of the pulse width signal, and thus the switch state of the main switch can be controlled according to the feedback signal.

[0060] In another embodiment of the present application, as Figure 7As shown, the switch control circuit includes a feedback signal processing circuit 116, a signal conversion circuit 126, and a drive signal generating circuit (not shown). The signal conversion circuit 126 includes a field effect transistor Q4 and a compensation signal generating circuit. The compensation signal generating circuit includes a fifth resistor R5, a first transconductance operational amplifier circuit, a second capacitor C2, a second transconductance operational amplifier circuit, and a third capacitor C3. A first end of the fifth resistor R5 is coupled to the second voltage, and a second end of the fifth resistor R5 is coupled to the drain of the field effect transistor. A first input end of the first transconductance operational amplifier circuit is coupled to the first end of the fifth resistor R5, and a second input end of the first transconductance operational amplifier circuit is coupled to the second end of the fifth resistor R5. A first end of the second capacitor C2 is coupled to an output end of the first transconductance operational amplifier circuit, a second end of the second capacitor C2 is coupled to a floating ground, and the first end of the second capacitor C2 outputs a voltage signal FBH. A first input end of the second transconductance operational amplifier circuit is coupled to the first end of the second capacitor C2, and a second end of the second transconductance operational amplifier circuit is coupled to a third reference signal end to obtain a third reference signal Vref3. A first end of the third capacitor C3 is coupled to an output end of the second transconductance operational amplifier circuit, a second end of the third capacitor C3 is coupled to a floating ground, and the first end of the third capacitor C3 outputs a compensation signal COMPH.

[0061] In combination Figure 2 It can be known that the drive signal generating circuit is a high-voltage side circuit, that is, the reference ground of the drive signal generating circuit is a floating ground, and that the drive signal generating circuit obtains the compensation signal COMPH through the signal conversion circuit. The specific working principle is as follows: when the output voltage Vout of the switch power supply decreases, the low-voltage side signal COMPL will increase, and the absolute value of the compensation signal COMPH will increase. According to the compensation signal COMPH, the drive signal generating circuit controls the turn-on time or the working frequency of the main switch tube to increase (or both the turn-on time and the working frequency to increase), the switch power supply transmits energy to increase, and the output voltage increases. Conversely, when the output voltage Vout of the switch power supply increases, the low-voltage side signal COMPL increases, and the absolute value of the compensation signal COMPH increases. According to the compensation signal COMPH, the high-voltage side control circuit controls the turn-on time or the working frequency of the main switch tube to decrease (or both the turn-on time and the working frequency to decrease), the switch power supply transmits energy to decrease, and the output voltage of the switch power supply decreases; finally, the output voltage of the switch power supply is controlled at a set value. Similarly, according to the above similar principle, the output current of the switch power supply can be controlled at a set value.

[0062] An embodiment of the present application also discloses a switch power supply. The switch power supply is a high-voltage side step-down switch power supply, and the switch power supply includes the switch control circuit according to any one of the above.

[0063] The embodiment of the present application also discloses a switching control method for controlling the switching control circuit, which comprises: receiving a feedback signal representing an output signal of the switching power supply, generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with input ground as reference ground; generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and generating a switching control signal according to the high-voltage side signal to control the main switch tube. In an embodiment, the switching control method is used to control the switching control circuit as described above.

[0064] In another embodiment of the present application, the switching control method comprises: receiving a feedback signal representing an output signal of the switching power supply at an input end of a feedback signal processing circuit, generating a low-voltage side signal according to the feedback signal by the feedback signal processing circuit, the feedback signal being a signal with input ground as reference ground. A signal conversion circuit generates a high-voltage side signal according to the low-voltage side signal, the high-voltage side signal being an analog signal. A driving signal generating circuit generates a switching control signal according to the high-voltage side signal to control the main switch tube.

[0065] In an embodiment of the present application, the low-voltage side signal is a current signal. In another embodiment, the step of generating the low-voltage side signal according to the feedback signal specifically comprises: generating a pulse width signal according to the feedback signal, the duty cycle of the pulse width signal being proportional to the feedback signal, the pulse width signal being the low-voltage side signal.

[0066] Those skilled in the art should know that the "high level" and "low level", "set" and "reset", "and gate" and "or gate", "in-phase input end" and "inverted input end" and other logic controls in the logical controls described in the specification or the drawings can be interchanged or changed, and the same functions or purposes as the above embodiments can be achieved by adjusting the subsequent logical controls.

[0067] The description and application of the present application herein are illustrative, and are not intended to limit the scope of the present application to the above embodiments. The effects or advantages related descriptions in the specification may not be embodied in actual experiments due to the uncertainty of specific conditions or other factors, and the effects or advantages related descriptions are not used to limit the scope of the application. Variations and changes of the disclosed embodiments are possible, and the alternatives and equivalent components of the embodiments are known to those skilled in the art. It should be clear to those skilled in the art that the present application can be realized in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential characteristics of the present application. Other variations and changes of the disclosed embodiments can be made without departing from the scope and spirit of the present application.

Claims

1. A switching control circuit for controlling the main switching transistor in a switching power supply, characterized in that, The switch power supply is a high-voltage side step-down switch power supply, and the switch control circuit comprises: a feedback signal processing circuit, an input end of which receives a feedback signal representing an output signal of the switch power supply, and is configured to generate a low-voltage side signal according to the feedback signal; the feedback signal is a signal with a reference ground as an input ground; a signal conversion circuit, a first end of which is coupled to an output end of the feedback signal processing circuit, and is configured to generate a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and a drive signal generation circuit, an input end of which is coupled to a second end of the signal conversion circuit, and an output end of which is configured to be coupled to a main switch tube, and is configured to generate a switch control signal according to the high-voltage side signal to control the main switch tube; wherein the signal conversion circuit comprises: a field effect tube, a source of which is coupled to the feedback signal processing circuit, and a control end of which is coupled to a first voltage; and a compensation signal generation circuit, an input end of which is coupled to a drain of the field effect tube, and an output end of which outputs a compensation signal, and is configured to generate the compensation signal according to a first current, the high-voltage side signal being the compensation signal, and the first current being a current flowing through the drain of the field effect tube; the compensation signal generation circuit comprises: a current mirror, a first end of which is coupled to the drain of the field effect tube; a third resistor, a first end of which is coupled to a second end of the current mirror; a fourth resistor, a first end of which is coupled to the second end of the current mirror; and a second capacitor, a first end of which is coupled to a second end of the fourth resistor, and a second end of which is coupled to a second end of the third resistor, and a first end of which outputs the compensation signal.

2. A switching control circuit for controlling a main switch in a switching power supply, characterized by The switch power supply is a high-voltage side step-down switch power supply, and the switch control circuit comprises: a feedback signal processing circuit, an input end of which receives a feedback signal representing an output signal of the switch power supply, and is configured to generate a low-voltage side signal according to the feedback signal; the feedback signal is a signal with a reference ground as an input ground; a signal conversion circuit, a first end of which is coupled to an output end of the feedback signal processing circuit, and is configured to generate a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and a drive signal generation circuit, an input end of which is coupled to a second end of the signal conversion circuit, and an output end of which is configured to be coupled to a main switch tube, and is configured to generate a switch control signal according to the high-voltage side signal to control the main switch tube; wherein the signal conversion circuit comprises: a field effect tube, a source of which is coupled to the feedback signal processing circuit, and a control end of which is coupled to a first voltage; and a compensation signal generation circuit, an input end of which is coupled to a drain of the field effect tube, and an output end of which outputs a compensation signal, and is configured to generate the compensation signal according to a first current, the high-voltage side signal being the compensation signal, and the first current being a current flowing through the drain of the field effect tube; the compensation signal generation circuit comprises: a fifth resistor, a first end of which is coupled to a second voltage, and a second end of which is coupled to the drain of the field effect tube; a first transconductance operational amplifier circuit, a first input end of which is coupled to the first end of the fifth resistor, and a second input end of which is coupled to the second end of the fifth resistor; a second capacitor, a first end of which is coupled to an output end of the first transconductance operational amplifier circuit, and a second end of which is coupled to a ground; a second transconductance operational amplifier circuit, a first input end of which is coupled to the first end of the second capacitor, and a second end of which is coupled to a third reference signal end to obtain a third reference signal; and A third capacitor, a first end of which is coupled to an output end of the second trans-impedance operational amplifier circuit, and a second end of which is coupled to ground, outputs a compensation signal at the first end.

3. A switch control circuit as claimed in claim 1 or 2, characterized in that The feedback signal processing circuit generates a low-voltage side signal according to the feedback signal, and the low-voltage side signal is a current signal.

4. The switch control circuit according to claim 1 or 2, wherein The feedback signal processing circuit includes: A pulse width generation circuit, an input end of which is coupled to the feedback signal end to receive the feedback signal, generates a pulse width signal according to the feedback signal, and a duty cycle of the pulse width signal is proportional to the feedback signal.

5. The switch control circuit of claim 3, wherein The feedback signal processing circuit includes: A first trans-impedance operational amplifier circuit, a first input end of which is coupled to the feedback signal end to receive the feedback signal, and a second input end of which is coupled to the first reference signal end to receive the first reference signal, outputs a low-voltage side signal at an output end thereof.

6. The switch control circuit according to claim 1 or 2, wherein The field effect transistor is an N-type junction field effect transistor or an N-type metal oxide semiconductor field effect transistor.

7. A switching power supply, characterized by comprising: The switching power supply is a high-voltage side step-down switching power supply, and the switching power supply includes the switching control circuit according to any one of claims 1-6.

8. A switching control method for controlling the switching control circuit according to claim 1 or 2, characterized by The switching control method includes: receiving a feedback signal representing an output signal of the switching power supply, and generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with a reference ground as an input ground; generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and generating a switching control signal according to the high-voltage side signal to control the main switch tube.

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