Control circuit and power supply method thereof

Abstract

The invention provides a control circuit for a switching power supply and a power supply method thereof. The control circuit comprises a logic control circuit, a driving circuit, a high-voltage power supply circuit, a first energy storage unit, a first power supply control circuit, a second energy storage unit and a second power supply control circuit, the input end of the driving circuit is coupled with the output end of the logic control circuit, and the output end of the driving circuit is coupled with the control end of the power switch tube; the input end of the high-voltage power supply circuit is coupled with a wire voltage end and the input end of the power switch tube, and the high-voltage power supply circuit is used for providing power for the control circuit; the first energy storage unit provides a first power supply voltage for supplying power to the logic control circuit; the first power supply control circuit is used for controlling the first energy storage unit to obtain electric energy from the output end of the high-voltage power supply circuit and isolating the high-voltage power supply circuit from the first energy storage unit; the second energy storage unit provides a second power supply voltage for supplying power to the driving circuit; the second power supply control circuit is used for controlling a second power supply voltage on the second energy storage unit. According to the control circuit and the power supply method, the integration level and the power supply capacity are improved, meanwhile, the problem of mutual interference of high and low power supplies is eliminated or reduced, and the reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of electronics, and specifically but not limited to, to a control circuit and a power supply method thereof. Background Art

[0002] In a switching power supply, in order to provide a stable working power supply to the control chip, an external capacitor is usually used in combination with a power supply control circuit to stabilize the power supply of the control chip at a certain value to ensure the normal operation of the control chip. With the development of technology, the integration of switching power supplies is getting higher and higher. In order to save costs and improve reliability, more peripheral devices are integrated into the chip, such as integrating the power capacitor into the control chip.

[0003] At the same time, the control chip usually requires two power supplies, the first power supply is used to power lower voltage units such as logic units, and the other power supply is used to power higher voltage power drive circuits. However, the two power supplies are prone to mutual interference. For example, the power drive circuit requires a large amount of energy, which can easily cause a drop in the power supply voltage and signal interference on the low voltage unit while powering the drive circuit, causing instability in the control circuit signal.

[0004] In view of this, it is necessary to provide a structure or a power supply method so as to solve or optimize the above-mentioned integration and mutual interference problems at the same time. Summary of the invention

[0005] In view of at least one or more problems in the background technology, the present invention proposes a control circuit and a power supply method for controlling a power switch tube in a switching power supply.

[0006] According to one aspect of the present invention, a control circuit for controlling a power switch tube in a switching power supply comprises: a logic control circuit, wherein an input end of the logic control circuit receives a feedback signal representing an output signal of the switching power supply, and an output end of the logic control circuit provides a logic control signal; a drive circuit, wherein an input end of the drive circuit is coupled to an output end of the logic control circuit, and an output end of the drive circuit is coupled to a control end of the power switch tube, and the drive circuit is used to drive the on and off states of the power switch tube under the control of the logic control circuit to adjust the output signal of the switching power supply; a high-voltage power supply circuit, wherein an input end of the high-voltage power supply circuit is coupled to a line voltage end and an input end of the power switch tube, and the high-voltage power supply circuit is used to provide power for the control circuit; a first energy storage unit, which provides a first power supply voltage for powering the logic control circuit; a first power supply control circuit, wherein the first power supply control circuit is used to control the first energy storage unit to obtain electric energy from the output end of the high-voltage power supply circuit and isolate the high-voltage power supply circuit from the first energy storage unit, and the first power supply control circuit controls the first power supply voltage on the first energy storage unit; a second energy storage unit, wherein the second energy storage unit provides a second power supply voltage for powering the drive circuit; and a second power supply control circuit, wherein the second power supply control circuit is used to control the second power supply voltage on the second energy storage unit.

[0007] Optionally, the high-voltage power supply circuit includes a junction field effect transistor (JFET), the power switch tube includes a metal oxide semiconductor field effect transistor (MOSFET), the drain of the JFET is coupled to the drain of the MOSFET, the source of the JFET is coupled to the input end of the first power supply control circuit and the second energy storage unit, and the gate of the MOSFET is connected to the output end of the drive circuit.

[0008] Optionally, the high-voltage power supply circuit includes a first high-voltage device and a second high-voltage device, wherein the input end of the first high-voltage device and the input end of the second high-voltage device are coupled to the line voltage end, the output end of the first high-voltage device is coupled to the input end of the first power supply control circuit, the output end of the first power supply control circuit is coupled to the first energy storage unit, and the output end of the second high-voltage device is coupled to the second energy storage unit.

[0009] Optionally, the second power supply control circuit controls the on and off states of the high-voltage power supply circuit to control the voltage on the second energy storage unit.

[0010] Optionally, the second power supply control circuit is located between the output end of the high-voltage power supply circuit and the second energy storage unit, and the second control circuit is used to convert the output end voltage of the high-voltage power supply circuit to the second power supply voltage and isolate the output end of the high-voltage power supply circuit from the second energy storage unit.

[0011] Optionally, the output end of the high-voltage power supply circuit is coupled to the output voltage signal feedback end of the control circuit through a switch, and the output voltage signal feedback end is coupled to the output end of the switching power supply through a unidirectional conductive device. When the line voltage is less than a threshold or the power switch tube is turned off, the high-voltage power supply circuit is turned off, and the output end of the switching power supply selectively supplies power to the control circuit.

[0012] Optionally, the input end of the second power supply control circuit is coupled to the first end of the second energy storage unit and the output end of the high-voltage power supply circuit, the second end of the second energy storage unit is coupled to the reference ground, and the output end of the second power supply control circuit provides a second supply voltage.

[0013] Optionally, the first power supply control circuit includes a linear voltage regulation circuit or a switch control conversion circuit, the input end of the first power supply control circuit is coupled to the output end of the high-voltage power supply circuit, the output end of the first power supply control circuit is coupled to the first end of the first energy storage unit and the power input end of the logic control circuit, and the second end of the first energy storage unit is coupled to the reference ground.

[0014] Preferably, the above control circuit is integrated in the same semiconductor chip.

[0015] According to another aspect of the present invention, a power supply method for a control circuit is proposed, wherein the control circuit is used to control a power switch tube in a switching power supply, the control circuit includes a logic control circuit and a drive circuit, the drive circuit amplifies the control signal output by the logic control circuit, and is used to drive the power switch tube. The power supply method includes: when the power switch tube is turned off, controlling the high-voltage power supply circuit to be turned on to draw power from the line voltage end; controlling and isolating the output voltage of the high-voltage power supply circuit through a first power supply control circuit, storing a first power supply in a first energy storage unit, and powering the logic control circuit; and controlling the output voltage of the high-voltage power supply circuit through a second power supply control circuit, storing a second power supply in a second energy storage unit, and powering the drive circuit.

[0016] Optionally, the method further comprises: when the switching power supply is operating normally and the power switch tube is at least partially turned on, controlling the high-voltage power supply circuit to be turned off and taking power from the output end of the switching power supply.

[0017] The control circuit and power supply method proposed in the present invention provide two independent power supply paths, integrate capacitors into integrated circuits, improve integration and power supply capabilities, and eliminate or reduce the problem of mutual interference between high and low power supplies, thereby improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the description to explain the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1shows a block diagram of a control circuit according to an embodiment of the present invention;

[0020] Figure 2 A control circuit according to a specific embodiment of the present invention is shown;

[0021] Figure 3 A control circuit according to another embodiment of the present invention is shown;

[0022] Figure 4 A schematic diagram of a control circuit block diagram according to an embodiment of the present invention is shown;

[0023] Figure 5 A switching power supply system according to an embodiment of the present invention is shown;

[0024] Figure 6 A schematic flow chart of a power supply method for a control circuit according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] In order 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, rather than limiting the claims of the present invention.

[0026] The description in this section is only for several typical embodiments, and the present invention is not limited to the scope of the embodiments. The combination of different embodiments, the mutual replacement of some technical features in different embodiments, and the mutual replacement of the same or similar prior art means with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0027] "Coupled" or "connected" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrical conductive medium such as a conductor, wherein the electrical conductive medium may contain parasitic inductance or parasitic capacitance, or a connection through an intermediate circuit or component described in the embodiments in the specification; indirect connection may also include a connection through other active or passive devices on the basis of achieving the same or similar functions, such as a connection through circuits or components such as switches, signal amplification circuits, and follower circuits. "Multiple" or "many" means two or more.

[0028] Figure 1The control circuit 100 according to an embodiment of the present invention is shown. The control circuit 100 is used to control the power switch tube 16 in the switching power supply. Preferably, the control circuit 100 is made on the same semiconductor substrate or integrated in the same semiconductor chip. The control circuit 100 includes two power supplies, providing two independent power supplies: a first power supply voltage source VDD and a second power supply voltage source VDDG, which are used to power the logic control circuit 13 and the drive circuit 15, respectively, wherein the first power supply voltage VDD for the logic control circuit 13 has a lower voltage value, and the second power supply voltage VDDG for the power drive circuit 15 has a higher voltage value and has a larger current output. The two power supplies each have independent energy storage units C1 and C2, so that the power supply VDDG does not affect the power supply capacity and signal fluctuation of the logic control circuit 13 when outputting a large current. Specifically, the control circuit 100 includes a high-voltage power supply circuit 11, a first power supply control circuit 12, a first energy storage unit C1, a logic control circuit 13, a second power supply control circuit 14, a second energy storage unit C2 and a drive circuit 15. In one embodiment, the control circuit 100 is fabricated on the same semiconductor substrate and integrated on the same semiconductor chip. The illustrated embodiment is integrated in a control chip. Through chip integration, the integration is enhanced, the external capacitor outside the integrated circuit chip or outside the package is eliminated, the external circuit is simplified, and the system reliability is increased. The input end of the logic control circuit 13 receives the feedback signal FB representing the output signal of the switching power supply, and the output end of the logic control circuit 13 provides the logic control signal CTL. The feedback signal end FB can receive a feedback signal representing the output voltage Vout of the output end of the switching power supply, and can also receive a feedback signal representing the output current. The input end of the drive circuit 15 is coupled to the output end of the logic control circuit 13, and the output end of the drive circuit 15 is coupled to the control end of the power switch tube 16. The drive circuit 15 is used to amplify the logic control signal CTL through the power supply of the second power supply voltage VDDG under the control of the logic control circuit CTL, and drive the power switch tube 16 to control the on and off state of the power switch tube 16 to adjust the corresponding output signal of the switching power supply. The input end of the high-voltage power supply circuit 11 is coupled to the line voltage end HV and the input end of the power switch tube 16. The high-voltage power supply circuit 11 is used to obtain energy from the line voltage end HV when it is turned on, and is used to provide power for the control circuit 100. In one embodiment, the line voltage end voltage HV is a voltage after the AC mains power supply is full-wave rectified and filtered. The input end of the power switch tube 16 is coupled to the line voltage end. When the power switch tube 16 is turned on, the switching power supply obtains energy from the line voltage end HV and converts the HV voltage source into an output signal of the switching power supply, supplies power to the load at the rear end of the switching power supply, and stores the energy in devices such as inductors and capacitors. When the power switch tube 16 is turned off, the energy stored in the inductor and capacitor continues to supply power to the load.Preferably, the switching power supply includes a step-down (Buck) circuit, the input end of the power switch tube 16 is coupled to the line voltage end HV, the output end of the power switch tube 16 is coupled to the first end of the rectifier tube and the first end of the inductor, the second end of the rectifier tube is coupled to the system ground, and the second end of the inductor is coupled to the output capacitor and the load. When the power switch tube 16 is turned off or turned on shallowly, the high-voltage power supply circuit 11 is turned on, and is used to supply power to the first energy storage unit C1 and / or the logic control circuit 13 under the control of the first power supply control circuit 12 and to supply power to the second energy storage unit C2 and / or the drive circuit 15 under the control of the second power supply control circuit 14. The first energy storage unit C1 obtains electrical energy from the output end of the high-voltage power supply circuit 11 under the control of the first power supply control circuit 12, and provides a first power supply voltage VDD for powering the logic control circuit 13. Preferably, the input end of the first power supply control circuit 12 is coupled to the output end of the high-voltage power supply circuit 11, the first end of the first energy storage unit C1 is coupled to the output end of the first power supply control circuit 12 and the power input end of the logic control circuit 13, the second end of the first energy storage unit C1 is coupled to the reference ground, and the first power supply voltage VDD on the first end of the first energy storage unit C1 is used to power the logic control circuit 13. The first power supply control circuit 12 isolates the first energy storage unit C1 from the high-voltage power supply unit 11, and controls the voltage value of the first power supply voltage VDD output by the first energy storage unit C1, so as to provide a stable voltage source with a suitable amplitude for the logic control circuit. The second power supply that provides the second power supply voltage VDDG for the drive circuit 15 includes a second energy storage unit C2 and a second power supply control circuit 14, the second power supply control circuit 14 is coupled to the high-voltage power supply circuit 11, and the second energy storage unit C2 obtains electric energy from the output end of the high-voltage power supply circuit 11 under the control of the second power supply control circuit 14, and provides a stable second power supply voltage VDDG higher than the first power supply voltage VDD at the first end of the second energy storage unit C2 for powering the drive circuit 15. The second end of the second energy storage unit C2 can be coupled to the reference ground. In this way, the second power supply voltage VDDG used to power the drive circuit 15 and the first power supply voltage VDD used to power the logic control circuit 13 each have an independent energy storage unit and a control circuit, and their power supplies are not affected by each other, the logic control circuit is not prone to signal fluctuations, and the system reliability is further enhanced. Moreover, dispersing the energy in an energy storage unit in two energy storage units can reduce the requirements for a single capacitance value, is more conducive to integration in a control chip, and improves the total power supply capacity. Preferably, the first energy storage unit C1 and the second energy storage unit C2 respectively include capacitors, wherein the capacitance value of the second energy storage unit C2 is greater than the capacitance value of the first energy storage unit C1.

[0029] Figure 2The control circuit 200 according to a specific embodiment of the present invention is shown. In this embodiment, the high-voltage power supply circuit 21 includes a junction field effect transistor (JFET), and the power switch tube 26 includes a metal oxide semiconductor field effect transistor (MOSFET), wherein the drain of the JFET is coupled to the drain of the MOSFET, the source of the JFET is coupled to the input end of the first power supply control circuit 22 and the second energy storage unit C2, and the gate of the MOSFET is connected to the output end of the driving circuit 25. The output end of the first power supply control circuit 22 is coupled to the first end of the first energy storage unit C1 and the power input end of the logic control circuit 23, and is used to supply power to the logic control circuit 23. The second end of the first energy storage unit C1 is coupled to the reference ground GND. In the illustrated embodiment, the reference ground GND is coupled to the second end of the current detection resistor Rcs, wherein the first end of the current detection resistor Rcs is coupled to the source of the power switch tube 26. In one embodiment, the reference ground GND and the system ground of the output end of the switching power supply are not grounded. In another embodiment, the reference ground GND and the system ground of the output end of the switching power supply are grounded. In one embodiment, a resistor can be set between the energy storage unit and the reference ground GND. In this embodiment, the first power supply control circuit 22 includes a linear voltage regulator circuit (LDO) coupled between the output end (source of JFET) of the high-voltage power supply circuit 21 and the capacitor C1. Of course, the first power supply control circuit may also include other types of circuits, such as a switch control conversion circuit (such as a Buck circuit, etc.), which is used to step down the voltage at the output end of the high-voltage power supply circuit 21 and convert it into a stable voltage, and provide a stable and lower first power supply voltage VDD for the power input end of the logic control circuit 23. In the illustrated embodiment, the first end of the second energy storage unit C2 is directly coupled to the output end of the high-voltage power supply circuit 21, the second end of the second energy storage unit C2 is grounded, and the output end of the second power supply control circuit 24 is directly coupled to the control end of the high-voltage power supply circuit 21, which is used to control the on and off state of the high-voltage power supply circuit 21, thereby controlling the output end of the high-voltage power supply circuit 21 to provide a stable second power supply voltage VDDG for powering the drive circuit 25. In one embodiment, the second power supply control circuit 24 controls the on and off state of the JFET 21 based on the second power supply voltage VDDG and the logic control signal CTL, wherein when the logic control signal CTL indicates that the power switch tube 26 is turned off, and the second power supply voltage VDDG is lower than a preset value, the second power supply control circuit 24 controls the JFET 21 to be turned on. In another embodiment, the second power supply control circuit 24 controls the on and off state of the high-voltage power supply circuit 21 based on the second power supply voltage VDDG and the line voltage terminal HV voltage.Optionally, the second power supply control circuit 24 includes a first power supply comparison circuit and a second power supply comparison circuit, wherein the input end of the first power supply comparison circuit is respectively coupled to the line voltage end HV and the threshold signal, and the input end of the second power supply comparison circuit is respectively coupled to the first end of the second energy storage unit C2 and the energy supply threshold signal. When the line voltage end HV voltage is greater than a threshold value and the second power supply voltage VDDG is lower than a preset value, the second power supply control circuit 24 controls the high-voltage power supply circuit 21 to be turned on, for supplying power to the second energy storage unit C2. When the line voltage end HV voltage is less than the threshold value or the second power supply voltage VDDG is higher than the corresponding preset value, the second power supply control circuit 24 controls the high-voltage power supply circuit 21 to be turned off, and the second energy storage unit C2 can supply power to the drive circuit 25 at this time. In the illustrated embodiment, the logic control circuit 23 receives feedback signals FB and CS representing the output signal of the switching power supply, and is used to provide a logic signal CTL. The signal FB is an output voltage feedback signal representing the output voltage of the switching power supply; the signal CS is a current feedback signal representing the current flowing through the power switch tube 26. Specifically, the logic control circuit 23 may include a first comparison circuit 231 , a second comparison circuit 232 and a trigger circuit 233 . In the illustrated embodiment, two input terminals of the first comparison circuit 231 are respectively coupled to the output voltage signal feedback terminal FB and the output voltage reference signal Vref. The first comparison circuit 231 is used to compare the feedback signal FB representing the output voltage of the switching power supply with the output voltage reference signal Vref. The output terminal of the first comparison circuit 231 is coupled to the set input terminal of the trigger circuit 233. Two input terminals of the second comparison circuit 232 are respectively coupled to the current sampling terminal CS and the peak reference signal Vipk. The output terminal of the second comparison circuit is coupled to the reset terminal of the trigger circuit 233. When the output voltage is lower than the preset value, the first comparison circuit 231 outputs a high level, the trigger circuit 233 is set, and the logic control signal CTL is a high level. The driving circuit 25 amplifies the high level signal CTL under the power supply of the second power supply voltage VDDG to turn on the power switch tube 26. When the current flowing through the power switch tube 26 rises to the peak threshold, the second comparison circuit 232 outputs a high level, the trigger circuit 233 is reset, and the logic control signal CTL is a low level to turn off the power switch tube 26. In other embodiments, the logic control circuit may have other structures and control methods. Preferably, the control circuit 200 is fabricated on the same semiconductor substrate, such as a silicon substrate, that is, integrated in a semiconductor chip. The "integration" here does not include packaging integration through electronic packaging technology. In the control circuit of the above embodiment, since the energy storage devices C1 and C2 are integrated in the semiconductor chip, no capacitor device is provided in or outside the electronic package, thereby simplifying the external circuit.

[0030] Figure 3 FIG. 3 shows a control circuit 300 according to another embodiment of the present invention. Figure 2Compared with the control circuit 200, the second power supply control circuit 34 is located between the output end of the high-voltage power supply circuit 31 and the second energy storage unit C2, and is used to isolate the output end of the high-voltage power supply circuit 31 from the second energy storage unit C2, and convert the output end voltage of the high-voltage power supply circuit 31 to the second power supply voltage VDDG, and the second energy storage unit C2 stores energy and supplies energy to the drive circuit. In the illustrated embodiment, the second power supply control circuit 34 includes a low voltage difference voltage stabilizing circuit, which is used to control the second energy storage unit C2 to have a stable second power supply voltage VDDG, the output end of the second power supply control circuit 34 is coupled to the first end of the second energy storage unit C2, and the second end of the second energy storage unit C2 is coupled to the reference ground GND.

[0031] In another embodiment, the second energy storage unit C2 is coupled to the output end of the high-voltage power supply circuit, the input end of the second power supply control circuit is coupled to the first end of the second energy storage unit and the output end of the high-voltage power supply circuit, the second end of the second energy storage unit is coupled to the reference ground, and the output end of the second power supply control circuit provides a second power supply voltage for powering the drive circuit. The second power supply control circuit may include a low voltage difference linear voltage regulator circuit.

[0032] Figure 4 FIG. 4 is a block diagram of a control circuit 400 according to an embodiment of the present invention. Figure 1 Compared with the control circuit 100 in FIG. 1 , the high-voltage power supply circuit in the control circuit 400 includes a first high-voltage device 411 and a second high-voltage device 412. The input end of the first high-voltage device 411 and the input end of the second high-voltage device 412 are coupled to the line voltage end HV, the output end of the first high-voltage device 411 is coupled to the input end of the first power supply control circuit 42, and the output end of the second high-voltage device 412 is coupled to the second power supply control circuit 44 and the second energy storage unit C2. The coupling method of the second high-voltage device 412, the second power supply control circuit 44 and the second energy storage unit C2 can be a combination of Figure 1-Figure 3 The coupling method of the high-voltage power supply circuit, the second power supply control circuit and the second energy storage unit C2 in any manner described. In one embodiment, the output end of the second power supply control circuit 44 can be directly coupled to the control end of the second high-voltage device 412 to control the voltage of the output end of the second high-voltage device 412, and the output end of the second high-voltage device 412 is coupled to the second energy storage unit C2 to provide a stable second power supply voltage VDDG.

[0033] Figure 5The switching power supply system 500 according to an embodiment of the present invention is shown. In this embodiment, the output end of the high-voltage power supply circuit 511 is coupled to the output voltage signal feedback end FB of the control circuit 50 through a selection switch K, and the output voltage Vout provides a feedback signal and a power supply to the control circuit 50 through a unidirectional conduction device D1. The switching power supply system 500 includes a control circuit 50, a step-down (Buck) circuit 51 and a unidirectional conduction device D1. The output end of the switching power supply provides an output voltage Vout for supplying power to the load. The unidirectional conduction device D1 is coupled between the output end of the switching power supply and the output voltage signal feedback end FB. The control circuit 50 includes a selection switch K, wherein the first end of the selection switch K is coupled to the output voltage signal feedback end FB, and the second end of the selection switch K is coupled to the output end of the high-voltage power supply circuit 511. The output end of the switching power supply can be used to selectively supply power to the output end of the high-voltage power supply circuit 511 through the selection switch K and the unidirectional conduction device D1. In the illustrated embodiment, the unidirectional conducting device D1 includes a diode, wherein the input end of the unidirectional conducting device D1, i.e., the anode of the diode D1, is coupled to the output end of the switching power supply, and the output end of the unidirectional conducting device D1, i.e., the cathode of the diode D1, is coupled to the output voltage signal feedback end FB of the control circuit 50, so that the current of the unidirectional conducting device D1 is allowed to flow from the output end of the switching power supply to the output end of the high-voltage power supply circuit 511. When the voltage at the line voltage terminal HV is less than the threshold or the power switch tube Q is turned off, the high-voltage power supply circuit 511 is turned off, and the output end of the switching power supply selectively supplies power to the control circuit 50 according to the on and off state of the selection switch K. For example, when the high-voltage power supply circuit 511 is turned off and the first power supply voltage VDD or the second power supply voltage VDDG is lower than the corresponding threshold, the selection switch K is turned on, so that the output end of the switching power supply supplies power to the logic control circuit or the drive circuit.

[0034] Figure 6 FIG. 6 is a flow chart of a method 600 for controlling a power supply of a circuit according to an embodiment of the present invention. Figure 1-Figure 5The control circuit shown. The power supply method 600 includes in a first step 601: when the power switch tube is turned off, the high-voltage power supply circuit is controlled to be turned on to draw power from the line voltage end. This step may further include, when the power switch tube is turned on but the depth of conduction is shallow, the high-voltage power supply circuit is also controlled to be turned on to draw power from the line voltage end. In step 602, a first energy storage unit and a first power supply control circuit are used to draw power from the output end of the high-voltage power supply circuit for powering the logic control circuit. In one embodiment, the output voltage of the high-voltage power supply circuit is controlled and isolated by the first power supply control circuit, and the first power supply is stored in the first energy storage unit for powering the logic control circuit. Specifically, the first power supply control circuit may include a linear voltage regulator circuit or a switch buck circuit, coupled between the output end of the high-voltage power supply circuit and the first energy storage unit, for reducing the output voltage of the high-voltage power supply circuit and isolating the output end of the high-voltage power supply circuit and the first energy storage unit. The power supply method 600 further includes in step 603, a second energy storage unit and a second power supply control circuit are used to draw power from the output end of the high-voltage power supply circuit for powering the drive circuit. Specifically, the output voltage of the high-voltage power supply circuit can be controlled by the second power supply control circuit, and the second power supply is stored in the second energy storage unit for powering the drive circuit. In one embodiment, the second energy storage unit is coupled to the output end of the high-voltage power supply circuit, and the second power supply control circuit can control the voltage on the second energy storage unit by controlling the high-voltage power supply circuit to be turned on and off. In another embodiment, the second power supply control circuit can be coupled between the output end of the high-voltage power supply circuit and the second energy storage unit to isolate and stabilize the voltage on the second energy storage unit. The second power supply control circuit may include a low voltage difference voltage stabilizing circuit. In one embodiment, the power supply method further includes controlling the high-voltage power supply circuit to be turned off and drawing power from the output end of the switching power supply when the switching power supply is operating normally and the power switch tube is at least partially turned on, that is, when the voltage at the line voltage end is low. To draw power from the output end of the switching power supply, a unidirectional conducting device can be coupled between the output end of the switching power supply and the output voltage signal feedback end of the control circuit, and a switch is set between the output voltage signal feedback end and the output end of the high-voltage power supply circuit. When the high-voltage power supply circuit is turned off and the voltage on the first energy storage power supply or the second energy storage power supply is lower than the corresponding threshold, or when the voltage at the output end of the high-voltage power supply circuit is lower than the normal threshold, the conducting switch is used to draw power from the output end of the switching power supply to power the logic control circuit and / or the drive circuit.

[0035] The description and application of the present invention here are illustrative, and it is not intended to limit the scope of the present invention to the above-mentioned embodiments. The effects or advantages involved in the specification may not be reflected in the actual experimental examples due to the uncertainty of specific condition parameters or other factors, and the effects or advantages are not used to limit the scope of the invention. The deformation and change of the embodiments disclosed here are possible, and the replacement of the embodiments and the various equivalent parts are well known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential features of the present invention. Other deformations and changes can be made to the embodiments disclosed here without departing from the scope and spirit of the present invention.

Claims

1. A control circuit for controlling a power switch tube in a switching power supply, comprising: A logic control circuit, wherein an input end of the logic control circuit receives a feedback signal representing an output signal of the switching power supply, and an output end of the logic control circuit provides a logic control signal; A driving circuit, wherein the input end of the driving circuit is coupled to the output end of the logic control circuit, the output end of the driving circuit is coupled to the control end of the power switch tube, and the driving circuit is used to drive the on and off states of the power switch tube under the control of the logic control circuit to adjust the output signal of the switching power supply; A high-voltage power supply circuit, the input end of which is coupled to the wiring voltage end and the input end of the power switch tube, and the high-voltage power supply circuit is used to provide power for the control circuit; A first energy storage unit, providing a first supply voltage for powering the logic control circuit; A first power supply control circuit, the first power supply control circuit is used to control the first energy storage unit to obtain electric energy from the output end of the high-voltage power supply circuit and isolate the high-voltage power supply circuit from the first energy storage unit, and the first power supply control circuit controls a first supply voltage on the first energy storage unit; A second energy storage unit, the second energy storage unit provides a second supply voltage for powering the drive circuit; as well as The second power supply control circuit is used to control the second power supply voltage on the second energy storage unit.

2. The control circuit as claimed in claim 1, wherein the high-voltage power supply circuit includes a junction field effect transistor (JFET), the power switch tube includes a metal oxide semiconductor field effect transistor (MOSFET), the drain of the JFET is coupled to the drain of the MOSFET, the source of the JFET is coupled to the input end of the first power supply control circuit and the second energy storage unit, and the gate of the MOSFET is connected to the output end of the drive circuit.

3. The control circuit as claimed in claim 1, wherein the high-voltage power supply circuit includes a first high-voltage device and a second high-voltage device, wherein the input end of the first high-voltage device and the input end of the second high-voltage device are coupled to the line voltage end, the output end of the first high-voltage device is coupled to the input end of the first power supply control circuit, the output end of the first power supply control circuit is coupled to the first energy storage unit, and the output end of the second high-voltage device is coupled to the second energy storage unit. 4 . The control circuit as claimed in claim 1 , wherein the second power supply control circuit controls the on and off states of the high voltage power supply circuit to control the voltage on the second energy storage unit.

5. The control circuit as claimed in claim 1, wherein the second power supply control circuit is located between the output end of the high-voltage power supply circuit and the second energy storage unit, and the second control circuit is used to convert the output end voltage of the high-voltage power supply circuit to the second power supply voltage, and isolate the output end of the high-voltage power supply circuit from the second energy storage unit.

6. A control circuit as described in claim 5, wherein the output end of the high-voltage power supply circuit is coupled to the output voltage signal feedback end of the control circuit through a selection switch, and the output voltage signal feedback end is coupled to the output end of the switching power supply through a unidirectional conductive device, and when the line voltage is less than a threshold or the power switch tube is turned off, the high-voltage power supply circuit is turned off, and the output end of the switching power supply selectively supplies power to the control circuit.

7. The control circuit as claimed in claim 6, wherein an input end of the second power supply control circuit is coupled to a first end of the second energy storage unit and an output end of the high-voltage power supply circuit, a second end of the second energy storage unit is coupled to a reference ground, and an output end of the second power supply control circuit provides a second power supply voltage.

8. The control circuit as claimed in claim 1, wherein the first power supply control circuit comprises a linear voltage regulator circuit or a switch control conversion circuit, an input end of the first power supply control circuit is coupled to an output end of a high-voltage power supply circuit, an output end of the first power supply control circuit is coupled to a first end of a first energy storage unit and a power input end of a logic control circuit, and a second end of the first energy storage unit is coupled to a reference ground.

9. The control circuit as claimed in claim 1, integrated in a same semiconductor chip.

10. A power supply method for a control circuit, wherein the control circuit is used to control a power switch tube in a switching power supply, the control circuit includes a logic control circuit and a drive circuit, the drive circuit amplifies a control signal output by the logic control circuit to drive the power switch tube, the power supply method comprising: When the power switch is turned off, the high-voltage power supply circuit is controlled to be turned on and power is taken from the line voltage end; The output voltage of the high-voltage power supply circuit is controlled and isolated by the first power supply control circuit, and the first power supply is stored in the first energy storage unit for supplying power to the logic control circuit; as well as The output voltage of the high-voltage power supply circuit is controlled by the second power supply control circuit, and the second power supply is stored in the second energy storage unit for supplying power to the drive circuit.

11. The method of claim 10, further comprising: When the switching power supply is operating normally and the power switch tube is at least partially turned on, the high-voltage power supply circuit is controlled to be turned off and power is taken from the output end of the switching power supply.

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