A switching power supply management circuit, a silicon carbide driver and a switching power supply system

Abstract

The application discloses a switching power supply management circuit, a silicon carbide driver and a switching power supply system, comprising a bandgap reference circuit, a power supply voltage division circuit, a driving circuit and a logic judgment circuit, the bandgap reference circuit has a first output end and a second output end, the first input end of the driving circuit is connected with the first output end of the bandgap reference circuit, the second input end of the driving circuit is connected with the output end of the power supply voltage division circuit, the third input end of the driving circuit is connected with the second output end of the bandgap reference circuit, the first input end of the logic judgment circuit is connected with the first output end of the driving circuit, the second input end of the logic judgment circuit is connected with the second output end of the driving circuit, and the output end of the logic judgment circuit is connected with the driving end of the power supply switch tube. In the process of controlling the power-on or power-off of the switching power supply system, the application is not affected by the change of the external environment temperature, avoids the normal power-on at high temperature and the failure of power-on at low temperature, or the abnormal work at high and low temperatures.

Description

Technical Field

[0001] This application relates to the field of switching power supply technology, and in particular to a switching power supply management circuit, a silicon carbide driver, and a switching power supply system. Background Technology

[0002] Switching power supplies, as core power supply devices for various electronic devices and industrial systems, are widely used in new energy, automotive electronics, and industrial automation. With the large-scale application of silicon carbide drivers in switching power supplies, the requirements for start-stop control accuracy and environmental adaptability of power systems are constantly increasing. Reliable power-on start-up and power-off stop threshold control are the foundation for ensuring stable system operation.

[0003] During the power-on and power-off processes of a switching power supply system, when the system power supply VDD exceeds the power-on start-up threshold voltage... Then, the silicon carbide driver drives the switching power supply system to work. When the system power supply VDD falls below the power-down stop threshold... Subsequently, the silicon carbide driver controls the switching power supply system to stop working. During the existing power-on startup process, the power-on startup threshold voltage... This is determined by the breakdown of N series-connected MOS diodes by the system power supply VDD, i.e. During the power-down process, the power-down stopping voltage threshold. This is determined by the breakdown of M series-connected MOS diodes by the system power supply VDD, i.e. Because the threshold voltage VTH of a MOS diode varies with temperature using a negative temperature coefficient, typically ranging from -0.5mV / ℃ to -2mV / ℃, if the chip's operating temperature is between -40℃ and 150℃, the threshold voltage variation for each MOS diode will be -95mV to -380mV. This will result in the power-on threshold voltage variation being amplified by a factor of N, and the power-off threshold voltage variation being amplified by a factor of M. In short, the power-on threshold voltage... and power-off threshold voltage The system is subject to very large fluctuations in external high and low temperatures, which often causes it to power on normally at high temperatures but fail to power on at low temperatures, or to malfunction at high and low temperatures. Summary of the Invention

[0004] The main purpose of this application is to provide a switching power supply management circuit, a silicon carbide driver, and a switching power supply system, which aims to solve the technical problem that the power-on threshold voltage and power-off threshold voltage of the existing switching power supply system fluctuate greatly due to changes in the ambient temperature, causing the switching power supply system to fail to power on and off normally.

[0005] To achieve the above objectives, this application proposes a switching power supply management circuit for use in a switching power supply system, wherein the switching power supply system includes a power switching transistor, and the switching power supply management circuit includes: A bandgap reference circuit has a first output terminal and a second output terminal, which are used to output a first zero-temperature drift reference voltage and a second zero-temperature drift reference voltage, respectively. A power supply voltage divider circuit, wherein the input terminal of the power supply voltage divider circuit is connected to the power supply, and the power supply voltage divider circuit is used to divide the power supply voltage and output the power supply voltage. A driving circuit, wherein the first input terminal of the driving circuit is connected to the first output terminal of the bandgap reference circuit, the second input terminal of the driving circuit is connected to the output terminal of the power supply voltage divider circuit, and the third input terminal of the driving circuit is connected to the second output terminal of the bandgap reference circuit; A logic judgment circuit, wherein the first input terminal of the logic judgment circuit is connected to the first output terminal of the driving circuit, the second input terminal of the logic judgment circuit is connected to the second output terminal of the driving circuit, and the output terminal of the logic judgment circuit is connected to the driving terminal of the power switch transistor; When the power supply voltage is greater than the first zero-temperature drift reference voltage, the first output terminal of the driving circuit outputs a first low-level signal to the logic judgment circuit, and the second output terminal of the driving circuit outputs a second low-level signal to the logic judgment circuit. When the logic judgment circuit receives the first low-level signal and the second low-level signal, it outputs an enable control signal to the power switch to drive the power switch to be powered on and turned on. When the power supply voltage is less than the second zero-temperature drift reference voltage, the second output terminal of the driving circuit outputs a second high-level signal to the logic judgment circuit. When the logic judgment circuit receives the second high-level signal, it outputs an enable cut-off signal to the power switch transistor to drive the power switch transistor to power off.

[0006] By adopting the above technical solution, during the power-on or power-off process of the switching power supply system, the zero-temperature drift reference voltage and the power supply voltage divider are used as reference voltages. As long as the power-on start-up voltage threshold is reached, an enable control signal is output to control the switching power supply system to start working. When the power-off stop voltage threshold is reached, an enable cut-off signal is output to control the switching power supply system to stop working. Thus, it is not affected by changes in the external ambient temperature, avoiding normal power-on at high temperatures but failure at low temperatures, or abnormal operation at high and low temperatures.

[0007] The bandgap reference circuit in the switching power supply management circuit described above includes: A first bandgap reference module, wherein the first bandgap reference module is used to output a first zero-temperature-drift reference voltage; The second bandgap reference module has its input terminal connected to the first output terminal of the driving circuit. When the first output terminal of the driving circuit outputs a first low-level signal, the second bandgap reference module outputs a second zero-temperature drift reference voltage.

[0008] The first bandgap reference module in the switching power supply management circuit described above includes: A startup module, wherein the startup module is used to provide a startup current; A bandgap reference core module, wherein the input terminal of the bandgap reference core module is connected to the output terminal of the startup module, and the output terminal of the bandgap reference core module is connected to the first input terminal of the drive circuit. The bandgap reference core module is used to generate the first zero-temperature drift reference voltage and output it to the drive circuit when it receives the startup current. The startup feedback terminal of the bandgap reference core module is connected to the feedback terminal of the startup module to control the startup module to stop working after the bandgap reference core module is started.

[0009] The startup module of the switching power supply management circuit described above includes: A current source unit, which is used to provide a startup current for the bandgap reference core module; The first current mirror unit has its input terminal connected to the start-up feedback terminal of the bandgap reference core module. A control unit, wherein the input terminal of the control unit is connected to the output terminal of the first current mirror unit, and the output terminal of the control unit is connected to the controlled terminal of the current source unit; The first current mirror unit is used to receive the start-up feedback signal from the bandgap reference core module and output a feedback control signal to the control unit so that the control unit controls the current source unit to stop outputting the start-up current.

[0010] The bandgap reference core module of the switching power supply management circuit described above includes: The core unit has its input terminal connected to the output terminal of the startup module and its output terminal connected to the first input terminal of the drive circuit. The core unit is used to generate the first zero-temperature drift reference voltage when it receives the startup current and output it to the drive circuit. The second current mirror unit has its input terminal connected to a DC power supply and its output terminal connected to the input terminal of the core unit. The second current mirror unit is used to provide a constant current drive current to the core unit so that the core unit can stably output the first zero-temperature drift reference voltage to the drive circuit.

[0011] The driving circuit in the switching power supply management circuit described above includes: The first comparison module has a first input terminal connected to the first output terminal of the bandgap reference circuit, a second input terminal connected to the output terminal of the power supply voltage divider circuit, and an output terminal connected to the first input terminal of the logic judgment circuit. The second comparison module has its first input terminal connected to the second output terminal of the bandgap reference circuit, its second input terminal connected to the output terminal of the power supply voltage divider circuit, and its output terminal connected to the second input terminal of the logic judgment circuit.

[0012] The logic judgment circuit in the switching power supply management circuit described above includes: The NAND module has its first input terminal connected to the first output terminal of the driving circuit, its second input terminal connected to the second output terminal of the driving circuit, and its output terminal connected to the driving terminal of the power switch transistor.

[0013] The power supply management circuit described above includes, in the case of, the power divider circuit: The first power supply voltage divider module has its input terminal connected to the power supply and its output terminal connected to the second input terminal of the first comparator module. The first power supply voltage divider module is used to divide the power supply and output the first power supply voltage to the first comparator module. The second power supply voltage divider module has its input terminal connected to the power supply and its output terminal connected to the second input terminal of the second comparison module. The second power supply voltage divider module is used to divide the power supply voltage and output the second power supply voltage to the second comparison module.

[0014] In addition, to achieve the above objectives, this application also proposes a silicon carbide driver, characterized in that the silicon carbide driver includes the switching power supply management circuit described above.

[0015] In addition, to achieve the above objectives, this application also proposes a switching power supply system, characterized in that the switching power supply system includes a silicon carbide driver as described above.

[0016] Compared with the prior art, the switching power supply management circuit, silicon carbide driver, and switching power supply system proposed in this invention have the following advantages: 1. The switching power supply management circuit proposed in this application uses the zero-temperature drift reference voltage and the power supply voltage divider as reference voltages during the power-on or power-off process of the switching power supply system. As long as the power-on start-up voltage threshold is reached, an enable control signal is output to control the switching power supply system to start working. When the power-off stop voltage threshold is reached, an enable cut-off signal is output to control the switching power supply system to stop working. Thus, it is not affected by changes in the external ambient temperature, avoiding normal power-on at high temperatures but failure at low temperatures, or abnormal operation at high and low temperatures. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a block diagram of the switch management circuit of this application; Figure 2 This is another structural block diagram of the switch management circuit of this application; Figure 3 This is a schematic block diagram of the circuit module of this application; Figure 4 This is the circuit schematic diagram of the switch management circuit of this application; Figure 5 This is a temperature drift curve of the power-on start voltage threshold and the power-off stop voltage threshold of this application; Figure 6 This is a timing diagram of the power-on and power-off processes of this application; Figure 7 This is a circuit schematic diagram of the switch management circuit of this application applied to a PSR switching power supply system; Figure 8 This is a schematic diagram of the switch management circuit applied to an SSR switching power supply system. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0022] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0023] During the power-on and power-off processes of a switching power supply system, when the system power supply VDD exceeds the power-on start-up threshold voltage... Then, the silicon carbide driver drives the switching power supply system to work. When the system power supply VDD falls below the power-down stop threshold... Subsequently, the silicon carbide driver controls the switching power supply system to stop working. During the existing power-on startup process, the power-on startup threshold voltage... This is determined by the breakdown of N series-connected MOS diodes by the system power supply VDD, i.e. During the power-down process, the power-down stopping voltage threshold. This is determined by the breakdown of M series-connected MOS diodes by the system power supply VDD, i.e. Due to the threshold voltage of the MOS diode The threshold voltage of a MOS diode varies with temperature, typically ranging from -0.5mV / ℃ to -2mV / ℃. If the chip operates within the range of -40℃ to 150℃, the threshold voltage change for each MOS diode will be -95mV to -380mV. This will result in an N-fold amplification of the power-on threshold voltage change and an M-fold amplification of the power-off threshold voltage change. In short, the power-on threshold voltage... and power-off threshold voltage The system is subject to very large fluctuations in external high and low temperatures, which often causes it to power on normally at high temperatures but fail to power on at low temperatures, or to malfunction at high and low temperatures.

[0024] To solve the above problems, please refer to Figure 1 As shown in the figure, this specification provides an embodiment of a switching power supply management circuit 200, applied in a switching power supply system. The switching power supply system includes a power switching transistor, and the switching power supply management circuit 200 includes: The bandgap reference circuit 210 has a first output terminal and a second output terminal, which are used to output a first zero-temperature drift reference voltage and a second zero-temperature drift reference voltage, respectively. A power supply voltage divider circuit 220 is provided, the input terminal of which is connected to the power supply. The power supply voltage divider circuit 220 is used to divide the power supply voltage and output the power supply voltage. The driving circuit 230 has a first input terminal connected to the first output terminal of the bandgap reference circuit 210, a second input terminal connected to the output terminal of the power supply voltage divider circuit 220, and a third input terminal connected to the second output terminal of the bandgap reference circuit 210. A logic judgment circuit 240 is provided, wherein the first input terminal of the logic judgment circuit 240 is connected to the first output terminal of the driving circuit 230, the second input terminal of the logic judgment circuit 240 is connected to the second output terminal of the driving circuit 230, and the output terminal of the logic judgment circuit 240 is connected to the driving terminal of the power switch transistor.

[0025] Specifically, when the power supply voltage is greater than the first zero-temperature drift reference voltage, the first output terminal of the driving circuit 230 outputs a first low-level signal to the logic judgment circuit 240, and the second output terminal of the driving circuit 230 outputs a second low-level signal to the logic judgment circuit 240. When the logic judgment circuit 240 receives the first low-level signal and the second low-level signal, it outputs an enable control signal to the power switch transistor to drive the power switch transistor to be powered on and turned on. When the power supply voltage is less than the second zero-temperature drift reference voltage, the second output terminal of the driving circuit 230 outputs a second high-level signal to the logic judgment circuit 240. When the logic judgment circuit 240 receives the second high-level signal, it outputs an enable cut-off signal to the power switch transistor to drive the power switch transistor to power off.

[0026] Reference Figure 4 As shown, when the switching power supply system is powered on, the bandgap reference circuit 210 outputs a precise first zero-temperature-drift reference voltage with zero-temperature-drift characteristics. Second zero temperature drift reference voltage The first zero-temperature drift reference voltage and the second zero-temperature drift reference voltage do not change with the change of the external temperature, thereby providing a stable reference voltage for the drive circuit 230 to determine whether the switching power supply system has reached the power-on start voltage threshold or the power-off stop voltage threshold, thereby avoiding normal power-on at high temperature but power-on failure at low temperature, or abnormal operation at high and low temperatures.

[0027] Continue to refer to Figure 5 and Figure 6As shown, combining the timing curves of the power-on and power-off processes of the switching power supply system, in this embodiment, when the switching power supply system is powered on, the power supply VDD starts to rise from 0V. At this time, the power supply voltage divider circuit 220 divides the power supply voltage to obtain the power supply voltage (VDD). and The voltage also gradually increases from 0V. During the initial power-on state, the voltage drop received by the drive circuit 230 is... Below the first zero-temperature drift reference voltage At this time, the first signal ON output by the first output terminal of the drive circuit 230 is a high-level signal. Since the logic judgment circuit 240 receives the high-level signal, it does not output the enable control signal. Therefore, the power switch transistor remains in the off state, that is, the switching power supply system is still in the stopped state. When the power supply VDD continues to rise to the power-on start-up voltage threshold At this time, we have: ; ; That is, when the power supply voltage divider circuit 220 divides the power supply voltage, the power supply voltage is divided. Greater than the first zero-temperature drift reference voltage When the first output terminal of the drive circuit 230 outputs a first signal ON as a low-level signal, the second zero-temperature drift reference voltage received by the drive circuit 230 at this time... It is also less than the voltage drop across the power supply. Right now: ; That is, at this time, the second signal OFF output by the second output terminal of the driving circuit 230 is also a low-level signal. Since the first signal ON and the second signal OFF received by the driving circuit 230 are both low-level signals, the logic judgment circuit 240 outputs a high-level signal (i.e., a control signal) to the power switch transistor to drive the power switch transistor to be powered on and turned on, thereby controlling the switching power supply system to start working.

[0028] When the switching power supply system is powered off, the power supply voltage VDD continuously drops to the power-down stop voltage threshold. At this time, we have: ; ; That is, when the power supply is divided Below the second zero temperature drift reference voltage When the second output terminal of the drive circuit 230 outputs a high-level signal OFF, the logic judgment circuit 240 outputs a low-level signal (i.e., the signal can be cut off) to the power switch transistor to drive the power switch transistor to power off, thereby controlling the switching power supply system to stop working. After the switching power supply system stops working, the power supply VDD continues to drop. When the power supply VDD drops to the minimum voltage threshold... At this time, due to the voltage division of the power supply Below the first zero-temperature drift reference voltage The first signal ON output by the drive circuit 230 flips to a high-level signal, thereby keeping the switching power supply system in a power-off locked state.

[0029] By adopting the above method, during the power-on or power-off process of the switching power supply system, the zero-temperature drift reference voltage and the power supply voltage divider are used as reference voltages. As long as the power-on start-up voltage threshold is reached, an enable control signal is output to control the switching power supply system to start working. When the power-off stop voltage threshold is reached, an enable cut-off signal is output to control the switching power supply system to stop working. Thus, it is not affected by changes in the external ambient temperature, avoiding normal power-on at high temperatures but failure at low temperatures, or abnormal operation at high and low temperatures.

[0030] In one feasible implementation, please refer to Figure 2 As shown, the switching power supply management circuit 200 further includes: The power supply circuit 250 has its input terminal connected to a power supply and its output terminal connected to the power supply terminal of the bandgap reference circuit 210. The power supply circuit 250 is used to provide power to the bandgap reference circuit 210.

[0031] In this embodiment, the power supply circuit 250 includes MOSFETs M1, M2, M3, M5, and M6, and a resistor RG6. The gates of MOSFETs M5 and M6 are connected to one end of the resistor RG6, and the other end of the resistor RG6 is connected to the drain of MOSFET M5 and the power supply VDD, respectively. The source of MOSFET M5 is connected to the input terminal of the bandgap reference circuit 210. The source of the MOSFET M6 is connected to ground by MOSFETs M1, M2 and M3 connected in series.

[0032] It should be noted that the MOS transistors M1-M3 are low-voltage NMOS transistors, and the MOS transistors M5-M6 are high-voltage NMOS transistors.

[0033] When the switching power supply system is powered on, the power supply VDD starts to rise from 0V. At this time, VDD pulls up the gate voltage of MOSFETs M5 and M6 through resistor RG6. When VDD continues to rise and exceeds the threshold voltage of MOSFETs M5 and M6, MOSFETs M5 and M6 turn on. At this time, VDD supplies power to the bandgap reference circuit 210 through MOSFET M5. Simultaneously, VDD flows to ground through MOSFET M6 and the series-connected MOSFETs M1-M3, thus providing a bias voltage for MOSFET M6. Assuming that MOSFETs M1-M3 have the same dimensions, their turn-on voltage threshold is... The gate-source voltage is That is, bias voltage have: ,when hour; ,when hour; This clamps the source voltage of MOSFET M6 within a safe voltage range, thereby stabilizing the gate voltages of MOSFETs M5 and M6, thus providing a relatively stable internal power supply for the bandgap reference circuit 210 that does not fluctuate with the power supply VDD.

[0034] In one feasible implementation, refer to Figure 3 As shown, the bandgap reference circuit 210 includes: The first bandgap reference module 211 is used to output a first zero-temperature drift reference voltage.

[0035] In this embodiment, the first bandgap reference module 211 includes: Start-up module 2111, the start-up module 2111 is used to provide start-up current; The bandgap reference core module 2112 has its input terminal connected to the output terminal of the startup module 2111, and its output terminal connected to the first input terminal of the drive circuit 230. When the startup current is received, the bandgap reference core module 2112 is controlled to generate the first zero-temperature drift reference voltage and output it to the drive circuit 230. The startup feedback terminal of the bandgap reference core module 2112 is connected to the feedback terminal of the startup module 2111 so as to control the startup module 2111 to stop working after the bandgap reference core module 2112 is started.

[0036] When the switching power supply system is first powered on, the MOSFETs / switches in the internal circuit structure of the bandgap reference core module 2112 are in the off state because it has just been powered on. As a result, the bandgap reference core module 2112 cannot reliably enter and stabilize in the normal working state during the power-on process. Therefore, the startup module 2111 is required to provide the initial startup current to the bandgap reference core module 2112 to drive it into a stable normal working state. After starting the bandgap reference core module 2112, the startup module 2111 stops working to avoid the startup module 2111 from continuously consuming unnecessary current and to prevent the startup module 2111 from interfering with the first zero-temperature drift reference voltage generated by the bandgap reference core module 2112.

[0037] In this embodiment, the startup module 2111 includes a current source unit, which is used to provide startup current to the bandgap reference core module 2112.

[0038] Reference Figure 4 As shown, the current source unit includes MOSFETs M13-M16. The output terminal of the power supply circuit 250 is connected to the source of MOSFETs M13-M16. The source of MOSFET M15 outputs a first startup current to the bandgap reference core module 2112, and the source of MOSFET M16 outputs a second startup current to the bandgap reference core module 2112.

[0039] It should be noted that the aforementioned MOSFETs M13-M16 are low-voltage PMOS transistors.

[0040] The startup module 2111 further includes a first current mirror unit and a control unit. The input terminal of the first current mirror unit is connected to the startup feedback terminal of the bandgap reference core module 2112, the output terminal of the first current mirror unit is connected to the input terminal of the control unit, and the output terminal of the control unit is connected to the controlled terminal of the current source unit. After receiving the startup feedback signal from the bandgap reference core module 2112, the first current mirror unit outputs a feedback control signal to the control unit so that the control unit controls the current source unit to stop outputting the startup current.

[0041] Continue to refer to Figure 4 As shown, the first current mirror unit includes a first current mirror composed of MOSFET M7 and MOSFET M8. The control unit includes MOSFET M9 and resistor RBG3. The start-up feedback terminal of the bandgap reference core module 2112 is connected to the source of MOSFET M7. The source of MOSFET M8 is connected to the gate of MOSFET M9. Resistor RGB3 is connected between the drain of MOSFET M9 and ground. The source of MOSFET M9 is connected to the controlled terminal of the current source unit (i.e., the gates of MOSFET M14 and MOSFET M15).

[0042] It should be noted that the two MOS transistors of the first current mirror can have different width-to-length ratios to form a current mirror structure with a ratio of 1:N. Of course, they can also have the same width-to-length ratio. This specification does not limit the embodiments in this way.

[0043] When the power supply circuit 250 first provides the supply voltage VB to the bandgap reference circuit 210, the bandgap reference core module 2112 cannot work. At this time, the first current mirror composed of MOSFETs M7 and M8 also cannot work. Since the source of MOSFET M13 receives the supply voltage VB output by the power supply circuit 250, MOSFET M13 is turned on. Assuming the turn-on voltage threshold of MOSFET M13 is... The gate-source voltage is Then we have: ;when hour; in, The bias voltage provided to the gate of MOSFET M9 after MOSFET M13 is turned on; Simultaneously, the sources of MOSFETs M14, M15, and M16 receive the supply voltage VB from the output terminal of the power supply circuit 250, causing MOSFETs M14, M15, and M16 to conduct. Consequently, the drain of MOSFET M15 outputs a first startup current I2, and the drain of MOSFET M16 outputs a second startup current I3. Assuming that MOSFETs M14, M15, and M16 have the same dimensions, then: ; in, This is the gate-source voltage of MOSFET M9.

[0044] Continue to refer to Figure 4 As shown, the bandgap reference core module 2112 of this embodiment includes a core unit. The input terminal of the core unit is connected to the output terminal of the startup module 2111, and the output terminal of the core unit is connected to the first input terminal of the drive circuit 230. The core unit is used to generate the first zero-temperature drift reference voltage when it receives the startup current, and output it to the drive circuit 230. The second current mirror unit has its input terminal connected to a DC power supply and its output terminal connected to the input terminal of the core unit. The second current mirror unit is used to provide a constant current drive current to the core unit so that the core unit can stably output the first zero-temperature drift reference voltage to the drive circuit 230.

[0045] Continue to refer to Figure 4As shown, the core unit includes a first branch composed of MOSFET M10A, MOSFET M10 and switch Q1, a second branch composed of MOSFET M11, MOSFET M11A and switch Q2, a third branch composed of MOSFET 12, MOSFET 12A and switch Q3, and a fourth branch composed of resistor RBG2 and switch Q4. The second current mirror unit includes a second current mirror composed of MOSFET M17 and MOSFET M17A, a third current mirror composed of MOSFET M18 and MOSFET M18A, a fourth current mirror composed of MOSFET M19 and MOSFET M19A, a fifth current mirror composed of MOSFET M20 and MOSFET M20A, and a sixth current mirror composed of MOSFET M21 and MOSFET M21A. The output of the second current mirror is connected to the input of the first current mirror. The input of the first branch is connected to the drain of MOSFET M15 and the output of the third current mirror. The input of the second branch is connected to the drain of MOSFET M16 and the output of the fourth current mirror. The input of the third branch is connected to the output of the fifth current mirror. The input of the fourth branch is connected to the output of the sixth current mirror.

[0046] It should be noted that the size ratio of the second, third, fourth, fifth, and sixth current mirrors is 1:1:4:1:2, forming a current mirror structure with a ratio of 1:1:4:1:2. Of course, the size ratio of the second, third, fourth, fifth, and sixth current mirrors can also be adjusted according to actual needs. However, the embodiments in this specification are not limited here.

[0047] When the first branch, composed of MOSFET M10A, MOSFET M10, and switch Q1, receives the first startup current I2 from the drain of MOSFET M15, MOSFETs M10A, M10, and switch Q1 turn on, providing a bias voltage to the gates of MOSFETs M11 and M11A in the second branch, causing them to turn on. Simultaneously, the second startup current I3 from the drain of MOSFET M16 provides a bias voltage to the gates of MOSFETs 12 and 12A in the third branch, causing them to turn on as well, thus turning on switches Q2 and Q3. This process continues in the first, second, and third branches... After the circuit is turned on, the third current mirror composed of MOSFETs M18 and M18A, the fourth current mirror composed of MOSFETs M19 and M19A, and the fifth current mirror composed of MOSFETs M20 and M20A provide start-up current, switching them from the off state to the on state. After the third current mirror is turned on, a bias voltage is provided to the gates of MOSFETs M17 and M17A, turning on MOSFETs M17 and M17A, thus turning on the second current mirror as well. Similarly, the sixth current mirror composed of MOSFETs M21 and M21A is also turned on. At this point, the bandgap reference core module 2112 starts working and outputs the first zero-temperature drift reference voltage.

[0048] Furthermore, the second current mirror, composed of MOSFETs M17 and M17A, outputs a current source (i.e., a start-up feedback signal) to the first current mirror, composed of MOSFETs M7 and M8, after being amplified by the first current mirror (1:N ratio). This amplifies the bias voltage provided to the gate of MOSFET M9. The current is pulled down to near ground potential, thus turning off MOSFET M9. After MOSFET M9 turns off, MOSFETs M13, M14, M15, and M16 also turn off. Therefore, MOSFETs M15 and M16 stop providing the first startup current I2 and the second startup current I3 to the bandgap reference core module 2112. After the bandgap reference core module 2112 starts up, the third current mirror composed of MOSFETs M18 and M18A, and the fourth current mirror composed of MOSFETs M19 and M19A, replace MOSFETs M15 and M16 in providing the first startup current I2 and the second startup current I3 to the core module, enabling the bandgap reference core module 2112 to maintain stable operation.

[0049] It is worth noting that during the process of generating the first zero-temperature-drift reference voltage in the bandgap reference core module 2112, the function of the MOSFET M10A, MOSFET M10, and switch Q1 in the first branch is to provide bias voltage to the gates of the MOSFETs M11 and M11A in the second branch. Assume the gate-source voltage of MOSFET M10 is The gate-source voltage of MOSFET M10A is The base-emitter junction voltages of switching transistors Q1, Q2, and Q4 are: The base-emitter junction voltage of the switching transistor Q3 is Then the bias voltage have: ; MOSFETs M11 and M12 clamp the emitter of switch Q2 and one end of resistor RGB1 together, while MOSFETs M11A and M12A increase the output impedance and improve power supply rejection. and The voltage difference is even smaller, specifically: ; ; ; ; Similarly, the function of MOSFETs M17A-M21A is also to improve power supply rejection capability, allowing for higher matching accuracy of the second current mirror unit and more precise current mirroring. Since the second current mirror unit has a 1:1:4:1:2 current mirror structure, therefore: ; ; in, This is the thermal voltage, which is typically around 26mV at room temperature. Then we have: ; Where VT is the positive temperature coefficient. It has a negative temperature coefficient, so by setting... This will generate the first zero-temperature-drift reference voltage.

[0050] In one feasible implementation, refer to Figure 3 As shown, the bandgap reference circuit 210 further includes: The second bandgap reference module 212 has its input terminal connected to the first output terminal of the driving circuit 230. The second bandgap reference module 212 is used to output a second zero-temperature drift reference voltage when it receives a first low-level signal from the first output terminal of the driving circuit 230.

[0051] It should be noted that the second bandgap reference module 212 can be a power supply chip for generating a reference voltage, such as a chip of the ADR34 series or REF30 series.

[0052] In this embodiment, when the switching power supply system is first powered on, the power divider circuit 220 outputs a power divider voltage. Below the first zero-temperature drift reference voltage At this time, the first signal ON output by the first output terminal of the drive circuit 230 is a high-level signal. Since the second bandgap reference module 212 receives a high-level signal, it does not work. When the power supply VDD continues to rise to the power-on start-up voltage threshold... At that time, that is, the power supply voltage is divided. Greater than the first zero-temperature drift reference voltage At this time, the first signal ON output from the first output terminal of the drive circuit 230 is a low-level signal, and the second bandgap reference module 212 starts running to generate a precise second zero-temperature-drift reference voltage with zero-temperature-drift characteristics. .

[0053] In one feasible implementation, please refer to Figure 3 As shown, the driving circuit 230 includes: First comparison module 231, the first input terminal of the first comparison module 231 is connected to the first output terminal of the bandgap reference circuit 210, the second input terminal of the first comparison module 231 is connected to the first output terminal of the power supply voltage divider circuit 220, and the output terminal of the first comparison module 231 is connected to the first input terminal of the logic judgment circuit 240. The second comparison module 232 has its first input terminal connected to the second output terminal of the bandgap reference circuit 210, its second input terminal connected to the second output terminal of the power supply voltage divider circuit 220, and its second output terminal connected to the second input terminal of the logic judgment circuit 240.

[0054] In this embodiment, refer to Figure 4 As shown, the first comparison module 231 includes a first comparator U1. The positive input terminal of the first comparator U1 is connected to the output terminal of the first bandgap reference module 211, the negative input terminal of the first comparator U1 is connected to the first output terminal of the power supply voltage divider circuit 220, and the output terminal of the first comparator is connected to the first input terminal of the logic judgment circuit 240 and the input terminal of the second bandgap reference module 212, respectively.

[0055] When the switching power supply system is first powered on, the first comparator U1 receives the power supply voltage divider. Below the first zero-temperature drift reference voltage When the first signal ON output by the first comparator U1 is high, the second bandgap reference module 212 is not working. This prevents the second bandgap reference module 212 from activating when the power supply is undervoltage or unstable, which could cause the output second zero-temperature drift reference voltage to become inaccurate. When the power supply VDD rises to the power-on startup voltage threshold... At that time, that is, the power supply voltage is divided. Greater than the first zero-temperature drift reference voltage At this time, the first signal ON output by the first comparator U1 is a low-level signal, which triggers the second bandgap reference module 212 to start running and generate the second zero-temperature drift reference voltage.

[0056] Furthermore, referring to Figure 4 As shown, the second comparison module 232 includes a second comparator U2. The positive input terminal of the second comparator U2 is connected to the output terminal of the second bandgap reference module 212, the inverting input terminal of the second comparator U2 is connected to the second output terminal of the power supply voltage divider circuit 220, and the output terminal of the second comparator U2 is connected to the second input terminal of the logic judgment circuit 240.

[0057] In one feasible implementation, please refer to Figure 3 As shown, the power supply voltage divider circuit 220 includes: The first power supply voltage divider module 221 has its input terminal connected to the power supply and its output terminal connected to the second input terminal of the first comparison module 231. The first power supply voltage divider module 221 is used to divide the power supply and output the first power supply voltage to the first comparison module 231. The second power supply voltage divider module 222 has its input terminal connected to the power supply and its output terminal connected to the second input terminal of the second comparison module 232. The second power supply voltage divider module 222 is used to divide the power supply and output the second power supply voltage to the second comparison module 232.

[0058] In this embodiment, refer to Figure 4 As shown, the first power supply voltage divider module 221 includes a MOSFET M4, resistors RG1, RG2, and RG3. The power supply VDD is connected to one end of resistor RG1, and the other end of resistor RG1 is connected to one end of resistor RG2. The node where resistors RG1 and RG2 are connected in series is connected to the second input terminal of the first comparator module 231. The other end of resistor RG2 is connected to the source of MOSFET M4, and the gate of MOSFET M4 is connected to the output terminal of the first comparator module 231. Resistor RG3 is connected between the source and drain of MOSFET M4.

[0059] It should be noted that the MOS transistor M4 is a low-voltage NMOS transistor.

[0060] When the switching power supply system is powered on, the power supply VDD starts to rise from 0V. At this time, due to the voltage division of the power supply... Below the first zero-temperature drift reference voltage When the first signal ON output by the first comparator module 231 is a high-level signal, the gate of the MOSFET M4 receives the high-level signal output by the first comparator module 231, and the MOSFET M4 turns on, thereby short-circuiting the resistor RG3. At this time, the power supply voltage divider... In reality, it is obtained by voltage division between resistors RG1 and RG2. When the power supply VDD continues to rise to the power-on startup voltage threshold... When the signal ON output by the first comparator module 231 is low, the MOSFET M4 is turned off, thus connecting resistor RG3 to the series-connected resistors RG1 and RG2. At this time, the first power supply voltage divider... It is obtained by voltage division of resistors RG1, RG2 and RG3.

[0061] In this embodiment, the power supply VDD reaches the power-on startup voltage threshold. When the voltage is divided, resistor RG3 is used to prevent the power supply VDD voltage from being too high and exceeding the safe operating voltage range of the drive circuit 230, which would cause the drive circuit 230 to burn out.

[0062] Reference Figure 4 As shown, the second power supply voltage divider module 222 includes resistors RG4 and RG5 connected in series. The power supply VDD is connected to one end of the series connection between resistors RG4 and RG5, and the other end of the series connection between resistors RG4 and RG5 is grounded. The node where resistors RG4 and RG5 are connected in series is connected to the second input terminal of the second comparison module 232.

[0063] In this embodiment, independent first power supply voltage divider module and second power supply voltage divider module are set to provide reference voltages for the first comparison module and the second comparison module respectively, thereby avoiding mutual coupling interference between the power-on and power-off control processes of the switching power supply system, which would prevent the switching power supply system from starting or stopping normally.

[0064] In one feasible implementation, the logic judgment circuit 240 includes: The NAND module has its first input terminal connected to the first output terminal of the drive circuit 230, its second input terminal connected to the second output terminal of the drive circuit 230, and its output terminal connected to the drive terminal of the power switch transistor.

[0065] In this embodiment, the NAND module includes a NAND gate. The first input terminal of the NAND gate is connected to the output terminal of the first comparison module 231, the second input terminal of the NAND gate is connected to the output terminal of the second comparison module 232, and the output terminal of the NAND gate is connected to the driving terminal of the power switch transistor.

[0066] Reference Figure 5 The timing curves show that when the switching power supply system is powered off, the power supply voltage VDD continuously drops to the power-off stop voltage threshold. At this time, the first signal ON output by the first comparison module 231 is a low-level signal, and the second signal OFF output by the second comparison module 232 flips from a low-level signal to a high-level signal. To avoid signal timing disorder at this moment, which could lead to inaccurate output of the enable / disable control signal and cause abnormal power-off of the switching power supply system, this embodiment uses the NAND logic of a NAND gate to output a low-level signal (i.e., enable / disable control signal) the instant the second signal OFF output by the second comparison module 232 flips to a high-level signal. This ensures that the power supply VDD continues to drop to the power-off stop voltage threshold. In such cases, the power supply system can be immediately shut down.

[0067] This specification also provides a silicon carbide driver 100, which includes the switching power supply management circuit 200 as described above.

[0068] It is worth noting that since the silicon carbide driver 100 in this specification is based on the aforementioned switching power supply management circuit 200, the embodiments of the silicon carbide driver 100 proposed in this specification include all the technical solutions of all embodiments of the aforementioned switching power supply management circuit 200, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0069] Please refer to Figure 7 and Figure 8 As shown in the embodiments of this specification, a switching power supply system 1000 is also provided, which includes the silicon carbide driver 100 as described above.

[0070] It should be noted that the aforementioned switching power supply system 1000 can be a primary-side feedback control switching power supply system (i.e., a PSR switching power supply system), or a secondary-side feedback control switching power supply system 1000A (i.e., an SSR switching power supply system), or of course, other types of switching power supply systems. This specification does not limit the specific type of switching power supply system.

[0071] It is worth noting that since the switching power supply system in this specification is based on the aforementioned silicon carbide driver, the embodiments of the switching power supply system proposed in this specification include all the technical solutions of all embodiments of the aforementioned silicon carbide driver and switching power supply management circuit, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0072] Those skilled in the art should understand that the above-described embodiments are provided in conjunction with specific content and are not intended to limit the specific implementation of the present invention to these descriptions. Furthermore, due to differences in industry naming conventions, the invention is not limited to the above names or English names. Any methods or structures similar to or identical to those of the present invention, or any technical deductions or substitutions made based on the concept of the present invention, should be considered within the scope of protection of the present invention.

Claims

1. A switching power supply management circuit, characterized in that, Applied in a switching power supply system, the switching power supply system includes a power switching transistor, and the switching power supply management circuit includes: A bandgap reference circuit has a first output terminal and a second output terminal, which are used to output a first zero-temperature drift reference voltage and a second zero-temperature drift reference voltage, respectively. A power supply voltage divider circuit, wherein the input terminal of the power supply voltage divider circuit is connected to the power supply, and the power supply voltage divider circuit is used to divide the power supply voltage and output the power supply voltage. A driving circuit, wherein the first input terminal of the driving circuit is connected to the first output terminal of the bandgap reference circuit, the second input terminal of the driving circuit is connected to the output terminal of the power supply voltage divider circuit, and the third input terminal of the driving circuit is connected to the second output terminal of the bandgap reference circuit; A logic judgment circuit, wherein the first input terminal of the logic judgment circuit is connected to the first output terminal of the driving circuit, the second input terminal of the logic judgment circuit is connected to the second output terminal of the driving circuit, and the output terminal of the logic judgment circuit is connected to the driving terminal of the power switch transistor; When the power supply voltage is greater than the first zero-temperature drift reference voltage, the first output terminal of the driving circuit outputs a first low-level signal to the logic judgment circuit, and the second output terminal of the driving circuit outputs a second low-level signal to the logic judgment circuit. When the logic judgment circuit receives the first low-level signal and the second low-level signal, it outputs an enable control signal to the power switch to drive the power switch to be powered on and turned on. When the power supply voltage is less than the second zero-temperature drift reference voltage, the second output terminal of the driving circuit outputs a second high-level signal to the logic judgment circuit. When the logic judgment circuit receives the second high-level signal, it outputs an enable cut-off signal to the power switch transistor to drive the power switch transistor to power off.

2. The switching power supply management circuit according to claim 1, characterized in that, The bandgap reference circuit includes: A first bandgap reference module, wherein the first bandgap reference module is used to output a first zero-temperature-drift reference voltage; The second bandgap reference module has its input terminal connected to the first output terminal of the driving circuit. When the first output terminal of the driving circuit outputs a first low-level signal, the second bandgap reference module outputs a second zero-temperature drift reference voltage.

3. The switching power supply management circuit according to claim 2, characterized in that, The first bandgap reference module includes: A startup module, wherein the startup module is used to provide a startup current; A bandgap reference core module, wherein the input terminal of the bandgap reference core module is connected to the output terminal of the startup module, and the output terminal of the bandgap reference core module is connected to the first input terminal of the drive circuit. The bandgap reference core module is used to generate the first zero-temperature drift reference voltage and output it to the drive circuit when it receives the startup current. The startup feedback terminal of the bandgap reference core module is connected to the feedback terminal of the startup module to control the startup module to stop working after the bandgap reference core module is started.

4. The switching power supply management circuit according to claim 3, characterized in that, The startup module includes: A current source unit, which is used to provide a startup current for the bandgap reference core module; The first current mirror unit has its input terminal connected to the start-up feedback terminal of the bandgap reference core module. A control unit, wherein the input terminal of the control unit is connected to the output terminal of the first current mirror unit, and the output terminal of the control unit is connected to the controlled terminal of the current source unit; The first current mirror unit is used to receive the start-up feedback signal from the bandgap reference core module and output a feedback control signal to the control unit so that the control unit controls the current source unit to stop outputting the start-up current.

5. The switching power supply management circuit according to claim 3, characterized in that, The bandgap reference core module includes: The core unit has its input terminal connected to the output terminal of the startup module and its output terminal connected to the first input terminal of the drive circuit. The core unit is used to generate the first zero-temperature drift reference voltage when it receives the startup current and output it to the drive circuit. The second current mirror unit has its input terminal connected to a DC power supply and its output terminal connected to the input terminal of the core unit. The second current mirror unit is used to provide a constant current drive current to the core unit so that the core unit can stably output the first zero-temperature drift reference voltage to the drive circuit.

6. The switching power supply management circuit according to claim 1, characterized in that, The driving circuit includes: The first comparison module has a first input terminal connected to the first output terminal of the bandgap reference circuit, a second input terminal connected to the output terminal of the power supply voltage divider circuit, and an output terminal connected to the first input terminal of the logic judgment circuit. The second comparison module has its first input terminal connected to the second output terminal of the bandgap reference circuit, its second input terminal connected to the output terminal of the power supply voltage divider circuit, and its output terminal connected to the second input terminal of the logic judgment circuit.

7. The switching power supply management circuit according to claim 1, characterized in that, The logic judgment circuit includes: The NAND module has its first input terminal connected to the first output terminal of the driving circuit, its second input terminal connected to the second output terminal of the driving circuit, and its output terminal connected to the driving terminal of the power switch transistor.

8. The switching power supply management circuit according to claim 6, characterized in that, The power supply voltage divider circuit includes: The first power supply voltage divider module has its input terminal connected to the power supply and its output terminal connected to the second input terminal of the first comparator module. The first power supply voltage divider module is used to divide the power supply and output the first power supply voltage to the first comparator module. The second power supply voltage divider module has its input terminal connected to the power supply and its output terminal connected to the second input terminal of the second comparison module. The second power supply voltage divider module is used to divide the power supply voltage and output the second power supply voltage to the second comparison module.

9. A silicon carbide driver, characterized in that, The silicon carbide driver includes a switching power supply management circuit as described in any one of claims 1 to 8.

10. A switching power supply system, characterized in that, The switching power supply system includes the silicon carbide driver as described in claim 9.

Images