A voltage stabilizing driving circuit

Abstract

The application relates to the technical field of switching power supplies, and discloses a voltage stabilizing driving circuit applied to a switching power supply, wherein the switching power supply comprises a control unit and a power supply unit; the control unit outputs a driving signal to drive a switching tube; and the voltage stabilizing driving circuit comprises an inductor, a first end of the inductor is connected with an output end of the power supply unit, and is used for receiving a first voltage; and a voltage stabilizing driving module, a power input end of the voltage stabilizing driving module is connected with a second end of the inductor; the application can utilize the power supply voltage of an existing control unit without changing the parameter design of the control unit and the power supply circuit, can ensure that the voltage is maintained at a high level when the voltage is lower than a reasonable switching gate driving voltage, can realize reliable opening of the switching, can expand the application scene of a mature power supply chip on a third-generation semiconductor, does not need to spend time in reflowing and designing, and can greatly reduce the research and development period and cost.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, specifically to a voltage-regulated drive circuit. Background Technology

[0002] Third-generation semiconductors, primarily based on gallium nitride (GaN) and silicon carbide (SiC), have emerged in recent years and play a crucial role in high-power-density applications. GaN high electron mobility transistors have already become mainstream in the fast-charging adapter market, while SiC devices are gradually moving from industrial, automotive, and high-voltage applications to consumer applications. However, because the electron mobility of SiC materials in the channel of metal-oxide-semiconductor field-effect transistors (MOSFETs) is only about 1 / 10 that of silicon (Si) materials (approximately 10-50 cm² / V·s), its channel resistance accounts for as much as 40%-70% of the total on-resistance. With the gate oxide material still being silicon dioxide, a stronger vertical electric field, i.e., a higher gate drive voltage, is required to form a sufficient electron concentration in the inversion layer.

[0003] Specifically, SiC MOSFETs typically require a gate drive voltage of 18V to 20V. When the gate voltage is increased from 15V to 18V, the vertical electric field strength increases by approximately 20%, significantly improving the channel electron density. At 25°C, the electron concentration increases by approximately 30%, reducing the channel resistance by approximately 20-25%, thus improving the total on-resistance Rds(on). Furthermore, a higher gate voltage swing provides a larger drive current, which helps shorten switching time and reduce switching losses. In contrast, for the past 40 years, general-purpose low-to-medium power switching power supply control chips, when designing direct drive circuits, primarily considered driving a single silicon MOSFET, with a gate drive voltage typically of 9-12V. Further increasing this voltage does not effectively reduce the channel resistance of the silicon MOSFET. Emerging dedicated GaN power supply control chips, due to the fact that GaN devices typically employ a Schottky barrier gate structure and have a lower gate breakdown voltage, usually control the drive voltage at 5.5-6.5V.

[0004] Existing switching power supplies typically include a power stage circuit, a control unit, a power supply unit, and a rectification and filtering unit. The power stage circuit consists of an inductive element and a switching transistor connected in series. The power supply unit generates voltage through inductive coupling to power the control unit. Taking a flyback converter as an example, the power supply unit consists of a transformer auxiliary winding, diodes, and capacitors. The auxiliary winding generates voltage through coupling, which is then rectified to provide the control unit with the supply voltage VCC. Internally, the control unit regulates and clamps VCC, generating a drive signal (such as a GATE signal) to drive the switching transistor. Since the high level of the drive signal is usually obtained from VCC after internal circuitry processing, and considering the internal voltage drop, the high level of the drive signal is always lower than VCC. When the switching power supply enters a light-load mode, or when the second voltage decreases, VCC decreases accordingly, and the voltage amplitude of the drive signal also decreases.

[0005] To ensure that the voltage amplitude of the drive signal meets the driving requirements of third-generation semiconductor switches such as SiC MOSFETs under the above conditions, two main solutions have been proposed in the prior art: One approach is to increase the lower limit of VCC voltage by increasing the number of turns in the auxiliary winding. However, this method introduces greater losses, and the upper voltage limit of the control unit must not be exceeded, thus limiting its applicability.

[0006] Another approach is to add a dedicated drive unit between the control unit and the switching transistor, and simultaneously provide a higher-voltage auxiliary power supply to power this drive unit. This auxiliary power supply can draw power from the input, the output, or by adding a winding to couple power from the inductive element; its structure can be a linear regulator (LDO) or a switching converter. However, this approach incurs higher costs and has lower integration.

[0007] In addition, other related solutions have been proposed in the prior art. For example, Chinese invention patent CN117833608B discloses a gate-adjustable drive voltage circuit, which changes the drive voltage by adjusting the auxiliary power supply circuit of the flyback power supply circuit. However, its integration is not high, and it is mainly used in SiC tube double-pulse testing scenarios. Chinese invention patent CN115037164B discloses a wide-range output switching converter and its control method, which reduces power consumption by dynamically adjusting the supply voltage of the control circuit according to the feedback signal of the power stage circuit, but does not change the output level of the control unit. Chinese invention patent CN109039028B discloses a control circuit and a power adapter for use in a power adapter. It sets a voltage conversion unit inside the control circuit to change the VCC supply voltage, but it also does not change the output level of the control unit, and the voltage conversion unit is set inside the control unit rather than outside.

[0008] Therefore, how to reliably drive switching transistors (such as SiC MOSFETs) that require higher gate drive voltages using the drive signals output by the existing control unit without redesigning the control chip or adding an additional auxiliary power supply is a technical problem that urgently needs to be solved. Summary of the Invention

[0009] The purpose of this invention is to provide a voltage-regulated drive circuit to solve the problems mentioned in the background art.

[0010] In a first aspect, the present invention provides the following technical solution: a voltage-regulating drive circuit applied to a switching power supply, the switching power supply including a control unit and a power supply unit, the control unit outputting a drive signal to drive a switching transistor, the voltage-regulating drive circuit including: An inductor, the first end of which is connected to the output terminal of the power supply unit, for receiving a first voltage; A voltage regulator drive module, wherein the power input terminal of the voltage regulator drive module is connected to the second terminal of the inductor, the signal input terminal of the voltage regulator drive module is connected to the drive signal output terminal of the control unit, and the output terminal of the voltage regulator drive module is connected to the control terminal of the switching transistor; The voltage regulation drive module includes a voltage conversion unit and a level conversion unit. The voltage conversion unit is used to convert the first voltage into a stable second voltage. The level conversion unit is used to receive the drive signal output by the control unit, and convert the high level of the drive signal into a level consistent with the second voltage before outputting it to the control terminal of the switching transistor.

[0011] Furthermore, the voltage conversion unit includes: A first switch and a second switch, wherein the first switch is connected in series between the second terminal of the inductor and the second voltage, and the second switch is connected in series between the second terminal of the inductor and the reference ground; A logic control module is used to control the complementary conduction of the first switch and the second switch to generate a switching voltage at the second terminal of the inductor connected in series with the first switch and the second switch. An electronic module is provided to obtain electrical energy from the second terminal of the inductor to generate a working power supply and a reference voltage. An energy storage capacitor is connected between the second voltage and the reference ground to stabilize the second voltage.

[0012] Furthermore, the logic control module includes: The voltage divider detection submodule is used to detect the second voltage and generate a feedback voltage. The comparison control submodule is used to compare the feedback voltage with the reference voltage and control the first switch and the second switch to turn on and off according to the comparison result.

[0013] Furthermore, the voltage divider detection submodule includes a first voltage divider resistor and a second voltage divider resistor connected in series between the second voltage and the reference ground. The feedback voltage is generated at the common node of the first voltage divider resistor and the second voltage divider resistor. The comparison control submodule adjusts the on-time of the first switch and the second switch to make the feedback voltage approach the reference voltage, thereby stabilizing the second voltage at the target value.

[0014] Furthermore, the voltage conversion unit also includes a clamping diode, the cathode of which is connected to the second switch and the anode of which is connected to the reference ground, for clamping the second voltage below the clamping threshold when the second voltage exceeds the clamping threshold.

[0015] Furthermore, the logic control module controls the second switch to be turned on for a fixed on time, and calculates the on time of the first switch using the inductor volt-second balance principle based on the comparison result of the voltage at the common node and the reference voltage. After turning off the second switch, the first switch is turned on for a corresponding time to achieve complementary conduction between the first switch and the second switch.

[0016] Furthermore, the logic control module also includes a current detection submodule for detecting the current flowing through the second switch. The logic control module controls the peak current of the second switch based on the detected current to achieve adaptive on-time and switching frequency.

[0017] Furthermore, the level conversion unit includes a totem pole driving module, the input terminal of which is connected to the drive signal output terminal of the control unit, for receiving the drive signal output by the control unit.

[0018] Secondly, the present invention provides the following technical solution: a switching power supply, comprising: a power stage circuit, including a rectifier filter circuit, an electromagnetic interference filter protection circuit, and a synchronous rectification control circuit, for converting an input voltage into an output voltage; a control unit for outputting a drive signal; and a power supply unit for obtaining energy from the power stage circuit to generate a first voltage; It also includes the aforementioned voltage-regulating drive circuit, wherein the first end of the inductor of the voltage-regulating drive circuit is connected to the output end of the power supply unit, the signal input end of the voltage-regulating drive circuit is connected to the drive signal output end of the control unit, and the output end of the voltage-regulating drive circuit is connected to the control end of the switching transistor in the power stage circuit, for converting the high level of the drive signal output by the control unit into a stable second voltage level to drive the switching transistor.

[0019] Thirdly, the present invention provides the following technical solution: a driver chip, which integrates the voltage regulation driver circuit described above.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention can ensure that the voltage remains high when it is lower than the reasonable switching gate drive voltage without changing the design parameters of the control unit and power circuit. This enables reliable switching and expands the application scenarios of mature power chips in third-generation semiconductors. It eliminates the need to spend time redesigning the chip, greatly reducing the R&D cycle and cost.

[0021] 2. This invention does not require changes to the original power supply parameter design, such as inductors, transformers, or rectifier filter units, reducing the cost of redevelopment and having good compatibility and versatility.

[0022] 3. By setting voltage divider resistors (first voltage divider resistor and second voltage divider resistor), the present invention can generate different stable drive voltages by adjusting their ratio, thus flexibly adapting to the drive voltage requirements of different types of switching transistors.

[0023] 4. Compared with the existing technology that requires additional independent drive units and auxiliary power supplies, the present invention draws power directly from the original power supply unit, without the need to add an additional auxiliary power supply, resulting in higher integration and lower peripheral costs.

[0024] 5. The voltage regulator drive module of the present invention can be integrated into the same chip, requiring only a few external inductors and other components, which greatly reduces the area occupied by the printed circuit board and is conducive to the miniaturization of power supply products.

[0025] 6. This invention can be widely applied to various switching power supply topologies, such as Buck converters, Boost converters, Buck-Boost converters, Cuk converters, SEPIC converters, Zeta converters, flyback converters, and forward converters, and has broad applicability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a commonly used structure in existing switching power supplies; Figure 2 This is a schematic diagram of the corresponding structure of the Buck converter in the prior art; Figure 3 This is a schematic diagram of the corresponding structure of a flyback converter in the prior art; Figure 4 This is a waveform diagram showing the amplitude change of the GATE drive voltage when VCC changes in the existing technology; Figure 5A schematic diagram of a switching power supply structure that adds an independent drive unit and auxiliary power supply to the existing technology; Figure 6 This is a schematic diagram of a voltage regulator drive circuit applied to a switching power supply in an embodiment of the present invention; Figure 7 This is a schematic diagram of the voltage regulation drive circuit applied to the Buck converter in an embodiment of the present invention; Figure 8 This is a schematic diagram of the internal structure of a voltage-regulating drive circuit in an embodiment of the present invention; Figure 9 This is a key waveform diagram of the voltage-regulating drive circuit in an embodiment of the present invention; Figure 10 This is a schematic diagram of another internal structure of the voltage-regulating drive circuit in an embodiment of the present invention.

[0027] In the diagram, 10: Topology node; 20: Control unit; 30: Power supply unit; 40: Rectifier and filter unit; 50: Drive unit; 60: Auxiliary power supply; 70: Inductor; 80: Voltage regulator drive module; 101: Inductive element; 102: Switching transistor; 801: First switch; 802: Second switch; 803: Logic control module; 804: Resistor; 805: Power supply module; 806: Totem pole drive module; C1, C2, C3: Capacitors; D1, D2: Diodes; R1, R2: Resistors; Z1: Clamping diode; SW: Common node; VR: Second voltage; VCC: Supply voltage; GATE: Drive signal. Detailed Implementation

[0028] 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 some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] It should be understood that when a component or layer is referred to as being "on," "connected to," or "coupled to" other components or layers, it may be directly on, connected to, or coupled to other components or layers, or there may be intervening components or layers. Conversely, when a component is referred to as being "directly on," "directly connected to," or "directly coupled to" other components or layers, there are no intervening components or layers.

[0030] Figure 1 This is a schematic diagram of a commonly used structure in existing switching power supplies. For example... Figure 1As shown, existing switching power supplies typically include a topology node 10, a control unit 20, a power supply unit 30, and a rectification and filtering unit 40. The topology node 10 is composed of an inductive element 101 and a switching transistor 102 connected in series. The power supply unit 30 generates voltage through coupling with the inductive element 101 to supply power to the control unit 20.

[0031] Figure 2 This is a schematic diagram of the corresponding structure of a Buck converter in the prior art. (Example:) Figure 2 As shown, in the Buck converter, the power supply unit 30 consists of a diode D1 and a capacitor C1. When the inductive element 101 is freewheeling, it generates a supply voltage VCC on the capacitor C1 through the diode D1 to supply power to the control unit 20.

[0032] Figure 3 This is a schematic diagram of the corresponding structure of a flyback converter in the prior art. For example... Figure 3 As shown, in the flyback converter, the power supply unit 30 consists of a transformer auxiliary winding Na, a diode D1, and a capacitor C1; the rectifier and filter unit 40 also consists of a capacitor C2 and a diode D2.

[0033] Figure 4 This is a waveform diagram showing the amplitude change of the gate drive voltage when VCC changes, as described in existing technology. Figure 4 As shown, taking a flyback converter as an example, the control unit 20 internally generates a GATE signal to drive the switching transistor 102 after regulating and clamping VCC. Considering the internal voltage drop, the high level of the GATE signal is always lower than VCC. When the switching power supply enters a light-load mode, or when the second voltage decreases, VCC will decrease accordingly, and the voltage amplitude of the drive signal will also decrease accordingly. The lower limit of VCC voltage can be increased by increasing the number of turns in the auxiliary winding Na, but this will result in greater losses, and the upper voltage withstand limit of the control unit 20 must also be considered.

[0034] Figure 5 A schematic diagram of a switching power supply structure that adds an independent drive unit and auxiliary power supply to existing technologies. (Example) Figure 5 As shown, to enable flexible use of the control unit 20 among switching transistors made of different semiconductor materials, a dedicated drive unit 50 can be set between the control unit 20 and the switching transistor 102. Simultaneously, an auxiliary power supply 60 with a higher voltage is required to power the drive unit 50. This auxiliary power supply 60 can draw power from the input terminal, from the output terminal, or by adding a winding to couple power from the inductive element 101; its structure can be a linear regulator. However, this approach incurs significant additional costs. Example 1:

[0035] To resolve the problems existing in the above-mentioned prior art, please refer to Figure 6-10This invention provides a technical solution: a voltage-regulating drive circuit applied to a switching power supply. The switching power supply includes a control unit 20 and a power supply unit 30. The control unit 20 outputs a drive signal to drive a switching transistor 102. The voltage-regulating drive circuit includes: an inductor 70, the first end of which is connected to the output terminal of the power supply unit 30 to receive a first voltage; a voltage-regulating drive module 80, the power input terminal of which is connected to the second end of the inductor 70, the signal input terminal of which is connected to the drive signal output terminal of the control unit 20, and the output terminal of which is connected to the control terminal of the switching transistor 102; the voltage-regulating drive module 80 includes a voltage conversion unit and a level conversion unit. The voltage conversion unit converts the first voltage into a stable second voltage, and the level conversion unit receives the drive signal output by the control unit and converts the high level of the drive signal into a level consistent with the second voltage before outputting it to the control terminal of the switching transistor.

[0036] Specifically, this invention adds an inductor 70 and a voltage regulator drive circuit 80 to the existing switching power supply circuit. The existing switching power supply includes a topology node 10, a control unit 20, a power supply unit 30, and a rectification and filtering unit 40. The topology node 10 is composed of an inductive element 101 and a switching transistor 102 connected in series. The power supply unit 30 generates a voltage VCC through coupling with the inductive element 101, supplying power to the control unit 20. The control unit 20 outputs a drive signal (such as a GATE signal) to drive the switching transistor 102. In this embodiment, the first end of the inductor 70 is connected to the output terminal (i.e., the VCC node) of the power supply unit 30, and the second end of the inductor 70 is connected to the power input terminal of the voltage regulator drive circuit 80. The signal input terminal of the voltage regulator drive circuit 80 is connected to the drive signal output terminal of the control unit 20, used to receive the drive signal output by the control unit 20. The output terminal of the voltage regulator drive circuit 80 is connected to the control terminal of the switching transistor 102, used to output a boosted drive signal to drive the switching transistor 102.

[0037] Please see Figure 7 This is a schematic diagram of a voltage-regulating drive circuit applied to a Buck converter in an embodiment of the present invention. Figure 7 As shown, in the Buck converter, the control unit 20 and the voltage regulator drive circuit 80 share the same reference ground (i.e., are connected to a common ground). Figure 2 Compared to the existing Buck converter structure shown, this invention adds an inductor 70 between the output terminal (VCC node) of the power supply unit 30 and the voltage regulation drive circuit 80. It should be noted that for other switching power supply topologies such as flyback converters, forward converters, Boost converters, Buck-Boost converters, Cuk converters, SEPIC converters, and Zeta converters, those skilled in the art can make corresponding modifications based on the teachings of this invention, and these modifications all fall within the protection scope of this invention.

[0038] Furthermore, the voltage conversion unit includes a first switch 801, a second switch 802, a logic control module 803, an energy supply module 805, an energy storage capacitor C3, voltage divider resistors R1 and R2, and a clamping diode Z1.

[0039] In this configuration, the first switch 801 is connected in series between the second terminal of inductor 70 and the second voltage, and the second switch 802 is connected in series between the second terminal of inductor 70 and reference ground. The first terminal of the first switch 801 is connected to node SW (i.e., the second terminal of inductor 70), and the second terminal of the first switch 801 is connected to the first terminal of the second switch 802. The second terminal of the second switch 802 is connected to reference ground. The common node of the first switch 801 and the second switch 802 is node SW, i.e., the second terminal of inductor 70. An energy storage capacitor C3 is connected between the second voltage VR and reference ground to store electrical energy and provide a stable second voltage.

[0040] The logic control module 803 controls the complementary conduction of the first switch 801 and the second switch 802 to generate a switching voltage at the common node of the first switch 801 and the second switch 802. That is, at any given time, at most one of the first switch 801 and the second switch 802 is in the on state to avoid shoot-through short circuits. Through the alternating on and off of the first switch 801 and the second switch 802, a switching voltage is generated at node SW. After filtering by the energy storage capacitor C3, a stable second voltage is output at node VR. The power supply module 805 draws electrical energy from node SW (i.e., the second terminal of inductor 70) to generate a working power supply Vs and a reference voltage Vref. The working power supply Vs powers the various functional sub-modules within the logic control module 803, and the reference voltage Vref serves as a reference for voltage feedback regulation. When the voltage at node VR rises to the startup voltage V1 of the power supply module 805, the power supply module 805 starts operating, outputting the working power supply Vs and the reference voltage Vref. If the output VCC of the power supply unit 30 drops, causing the average voltage of node SW to drop to the shutdown voltage V2 of the power supply module 805 (V2 < V1), the power supply module 805 stops providing the working power supply Vs and the reference voltage Vref, and the logic control module 803 stops operating. The power supply module 805 has a hysteresis startup characteristic, which prevents frequent startup and shutdown of the power supply module 805 when the voltage at node VR fluctuates near a threshold.

[0041] Furthermore, the logic control module 803 includes a voltage divider detection submodule and a comparison control submodule.

[0042] The voltage divider detection submodule is used to detect the second voltage and generate a feedback voltage. Specifically, the voltage divider detection submodule includes a first voltage divider resistor R1 and a second voltage divider resistor R2 connected in series between node VR and reference ground. A feedback voltage Vfb is generated at the common node of the first voltage divider resistor R1 and the second voltage divider resistor R2, i.e., Vfb = VR × R2 / (R1 + R2). The feedback voltage Vfb is proportional to the voltage of node VR, and therefore can reflect the voltage change of node VR.

[0043] The comparison control submodule compares the feedback voltage Vfb with the reference voltage Vref and controls the switching on and off of the first switch 801 and the second switch 802 based on the comparison result. Specifically, when Vfb < Vref, it indicates that the voltage of node VR is lower than the target value. The comparison control submodule controls the second switch 802 to turn on, allowing the inductor 70 to store energy. Then, it turns off the second switch 802 and turns on the first switch 801, allowing the inductor 70 to release energy to the energy storage capacitor C3, thereby increasing the voltage of node VR. When Vfb > Vref, it indicates that the voltage of node VR is higher than the target value. The comparison control submodule keeps the first switch 801 on or controls the first switch 801 to switch at a lower frequency, thereby decreasing the voltage of node VR. Through the above feedback adjustment process, the feedback voltage Vfb approaches the reference voltage Vref, thereby stabilizing the voltage of node VR at the target value. .

[0044] Specifically, in this embodiment, the logic control module 803 controls the second switch 802 to conduct for a fixed on-time (COT). Based on the comparison between the voltage at node SW and the reference voltage Vref, the module calculates the conduction time of the first switch 801 using the inductor volt-second balance principle. After turning off the second switch 802, the module turns on the first switch 801 for a corresponding time to achieve complementary conduction between the first switch 801 and the second switch 802. Specifically, the inductor volt-second balance principle states that under steady-state operating conditions, the sum of the volt-second product (i.e., the product of inductor voltage and time) of the inductor in one switching cycle is zero. Based on this, the conduction time of the first switch 801 required to maintain the stability of the second voltage can be calculated.

[0045] Furthermore, clamping diode Z1 is connected between node VR and reference ground. Specifically, the cathode of clamping diode Z1 is connected to node VR, and the anode of clamping diode Z1 is connected to reference ground. This clamping diode is used to clamp the second voltage below the clamping threshold when the second voltage exceeds the clamping threshold. Clamping diode Z1 has a clamping voltage VZ1. When the voltage at node VR exceeds VZ1, clamping diode Z1 conducts, clamping the voltage at node VR at VZ1, preventing the voltage at node VR from being too high and damaging subsequent circuits or switching transistor 102.

[0046] Furthermore, the level conversion unit includes a totem-pole drive module 806. The input terminal of the totem-pole drive module 806 is connected to the drive signal output terminal of the control unit 20 to receive the drive signal (such as the GATE signal) output by the control unit 20. The output terminal of the totem-pole drive module 806 is connected to the control terminal of the switching transistor 102. The totem-pole drive module 806 is configured to convert the high level of the received drive signal into a level consistent with the voltage of node VR (i.e., the second voltage) and then output it to the control terminal of the switching transistor 102. That is, even if the high level of the drive signal output by the control unit 20 is only 9-12V (a typical silicon MOSFET drive voltage), after the level conversion by the totem-pole drive module 806, the high level of the drive signal output to the switching transistor 102 can reach a higher voltage (e.g., 18V), thereby meeting the high gate drive voltage requirements of third-generation semiconductor switching transistors such as SiC MOSFETs.

[0047] In summary, the following is a combination of... Figure 8 and Figure 9 The working process of the voltage regulator drive circuit of the present invention is described in detail below: like Figure 9 As shown, the first voltage VCC output by the power supply unit 30 first reaches node SW through inductor 70. In the initial stage of circuit startup, the voltage at node SW gradually rises from zero. When the voltage at node SW gradually rises and reaches the startup voltage V1 of the power supply module 805, the power supply module 805 starts working, generating a working power supply Vs to power the logic control module 803, and simultaneously generating a reference voltage Vref. At this time, the logic control module 803 starts working, first controlling the first switch 801 to conduct (close). At this time, the voltage at node VR is equal to the voltage at node SW (i.e., V1). The logic control module 803 detects the feedback voltage Vfb through voltage divider resistors R1 and R2, and compares Vfb with the reference voltage Vref. If Vfb < Vref, it means the voltage at node VR is lower than the target value. The logic control module 803 first controls the first switch 801 to turn off, then controls the second switch 802 to turn on for a fixed duration, allowing inductor 70 to store energy. After the second switch 802 turns off, the logic control module 803 calculates the on-time of the first switch 801 based on the comparison between the voltage at node SW and the reference voltage Vref, using the inductor volt-second balance principle, and turns on the first switch 801 for the corresponding time, causing inductor 70 to release energy to the energy storage capacitor C3, thereby raising the voltage at node VR. This process is repeated until Vfb = Vref, and the voltage at node VR reaches the target value. At this point, the voltage at node VR is stabilized at the target value, such as... Figure 9 The VR waveform is shown in the image.

[0048] If Vfb > Vref due to loop overshoot or a continued rise in VCC output from power supply unit 30, it indicates that the voltage at node VR is already higher than the target value. The logic control module 803 maintains the first switch 801 on and the second switch 802 off. At this time, the voltage at node VR follows the first voltage VCC output from power supply unit 30 (the voltage after passing through inductor 70). Figure 9 The portion of the VR waveform above the stable value is shown.

[0049] If the VCC output of power supply unit 30 continues to rise, causing the voltage at node VR to exceed the clamping voltage VZ1 of clamping diode Z1, clamping diode Z1 will conduct, clamping the voltage at node VR at VZ1 to prevent overvoltage damage to subsequent circuits. Figure 9 The top of the VR waveform is clamped as shown.

[0050] If the VCC output of power supply unit 30 drops, causing the average voltage of node SW to drop to the shutdown voltage V2 of power supply module 805 (V2 < V1), power supply module 805 stops providing operating power Vs and reference voltage Vref, and logic control module 803 stops working. The aforementioned hysteresis setting, where the startup voltage V1 is greater than the shutdown voltage V2, prevents frequent startup and shutdown of power supply module 805 when the voltage of node VR fluctuates near the threshold, thus improving the stability of system operation.

[0051] It should be noted that the SW node will generate a switching waveform with high and low fluctuations when the first switch 801 and the second switch 802 switch switch. However, since the other end of the SW node is connected to the inductor 70, according to the inductor volt-second balance principle, the average value of the SW node voltage is equal to the first voltage VCC output by the power supply unit 30. Therefore, the voltage fluctuation of the SW node does not affect the detection and control of the VCC voltage by the logic control module 803.

[0052] During the above operation, the level conversion unit (totem pole drive module 806) continuously receives the drive signal output by the control unit 20, converts the high level of the drive signal into a level consistent with the voltage of node VR, and then outputs it to the control terminal of the switching transistor 102. For example... Figure 9 As shown in the waveform at the bottom, the high level of the original GATE signal output by the control unit 20 is VGATE_L (e.g., 9-12V), and the high level of the drive signal GATE_OUT after level conversion is VGATE_H (e.g., 18V), which is consistent with the voltage of node VR. Example 2:

[0053] Based on Example 1, and similar to Example 1 (e.g. Figure 8The difference from the structure shown is that the first switch 801 is replaced by a passive diode (i.e., a freewheeling diode). At the same time, the logic control module 803 also includes a current detection submodule, which is used to detect the current flowing through the second switch 802. The logic control module 803 controls the peak current of the second switch 102 according to the detected current to achieve adaptive conduction time and switching frequency.

[0054] Specifically, the logic control module 803 no longer detects the voltage of the SW node, but instead adds a resistor 804 to detect the current CS flowing through the second switch 802 (i.e., the current detection signal). The logic control module 803 controls the peak current of the second switch 802 based on the detected current CS, thereby achieving adaptive on-time and switching frequency.

[0055] Specifically, when the current flowing through the second switch 802 reaches a preset peak current threshold, the logic control module 803 controls the second switch 802 to turn off, allowing the diode 801 to freewheel, thus releasing energy from the inductor 70 to the energy storage capacitor C3. This method belongs to a different control method, and its final performance is different from... Figure 9 The results are basically the same, and the same method can achieve a stable output of the node VR voltage.

[0056] It should be noted that, in this embodiment, the resistor 804 used for current detection can be replaced by other current detection elements, such as a current mirror or a current transformer. Those skilled in the art can choose according to actual application requirements. The totem pole drive module 806 can also be implemented using a BJT (bipolar junction transistor) structure. These variations are all equivalent substitutions for the technical solution of this invention. Example 3:

[0057] Based on Embodiment 1, the present invention provides the following technical solution: a switching power supply, comprising: The power stage circuit (including topology node 10 and rectifier filter unit 40) is used to convert the input voltage into the output voltage; the specific topology of the power stage circuit can be any one of Buck converter, Boost converter, Buck-Boost converter, Cuk converter, SEPIC converter, Zeta converter, flyback converter or forward converter, etc.

[0058] Control unit 20 is used to output a drive signal (such as a PWM signal). Control unit 20 can be any type of switching power supply control chip, including but not limited to pulse width modulation (PWM) controllers, digital signal processors (DSPs), or application-specific integrated circuits (ASICs). Control unit 20 can be a control chip originally designed to drive silicon MOSFETs, and its output drive signal has a high level of 9-12V.

[0059] Power supply unit 30 is used to obtain energy from the power stage circuit to generate a first voltage VCC; the specific structure of power supply unit 30 depends on the topology of the power stage circuit. For example, in a Buck converter, power supply unit 30 consists of diode D1 and capacitor C1; in a flyback converter, power supply unit 30 consists of transformer auxiliary winding Na, diode D1, and capacitor C1.

[0060] It also includes the voltage regulator drive circuit (including inductor 70 and voltage regulator drive module 80) described in Embodiment 1 above. The first terminal of inductor 70 of the voltage regulator drive circuit is connected to the output terminal of power supply unit 30 to receive the first voltage VCC. The power input terminal of voltage regulator drive module 80 is connected to the second terminal of inductor 70, the signal input terminal of voltage regulator drive module 80 is connected to the drive signal output terminal of control unit 20, and the output terminal of voltage regulator drive module 80 is connected to the control terminal of switching transistor 102 in power stage circuit. Voltage regulator drive module 80 is used to convert the high level of the drive signal output by control unit 20 into a stable second voltage level to drive switching transistor 102.

[0061] In this embodiment, the reference ground of the control unit 20 and the voltage regulator drive module 80 is the same point (common ground connection), which allows the drive signal output by the control unit 20 to be directly received and processed by the voltage regulator drive module 80 without isolation processing, thus simplifying the circuit design.

[0062] In this embodiment, the switching transistor 102 in the power stage circuit is a third-generation semiconductor switching transistor, preferably a silicon carbide (SiC) MOSFET or a gallium nitride (GaN) HEMT. Since third-generation semiconductor switching transistors require higher gate drive voltages (e.g., 18-20V for SiC MOSFETs), while the high-level drive signal output by the control unit 20 is only 9-12V, the voltage regulation drive circuit of this embodiment can boost the high-level drive signal to a level consistent with the voltage of node VR (e.g., 18V), thereby meeting the drive requirements of the third-generation semiconductor switching transistor.

[0063] Preferably, in the above embodiments, the switching power supply may further include a rectifier filter circuit, an electromagnetic interference (EMI) filter protection circuit, a synchronous rectification control circuit, a power factor correction (PFC) circuit, etc., and the present invention does not limit this.

[0064] In summary, taking SiC MOSFETs as an example, they typically require an 18V gate drive voltage to achieve low on-resistance and high switching speed. Using the voltage-regulating drive circuit of this invention, when the first voltage VCC output by the power supply unit 30 varies over a wide range (e.g., 6V to 30V), the voltage at node VR can be stabilized at a target value (e.g., 18V) by appropriately setting the ratio of the voltage divider resistors R1 and R2. The level conversion unit converts the drive signal (e.g., 9V) output by the control unit 20 into an 18V drive signal and outputs it to the control terminal of the SiC MOSFET, enabling a traditional control chip that could only output a 9V drive signal to reliably drive the SiC MOSFET.

[0065] It should be noted that in the above embodiments, the voltage regulator drive module 80 (including at least the first switch 801, the second switch 802, the logic control module 803, the power supply module 805, and the totem pole drive module 806) is integrated into the same chip, while the inductor 70 is located outside the chip. The voltage divider resistors R1 and R2, the clamping diode Z1, and the energy storage capacitor C3 can be located outside the chip or integrated inside the chip according to actual application needs. Preferably, in order to reduce the number of external components and reduce the PCB board area, some or all of the voltage divider resistors R1 and R2, the clamping diode Z1, and the energy storage capacitor C3 can be integrated into the same chip.

[0066] In one optional embodiment, both the first switch 801 and the second switch 802 are metal-oxide-semiconductor field-effect transistors (MOSFETs), preferably N-type MOSFETs. The first switch 801 and the second switch 802 may also be insulated-gate bipolar transistors (IGBTs) or other types of controllable switching devices, which can be selected by those skilled in the art according to actual application requirements.

[0067] In one alternative implementation, the clamping diode Z1 is a Zener diode, and its voltage regulation value VZ1 is set according to the actual application requirements. It should be greater than the target drive voltage and less than the withstand voltage limit of the subsequent circuit.

[0068] In one alternative implementation, inductor 70 is a power inductor whose inductance value is selected based on parameters such as switching frequency and load current to ensure that the voltage conversion unit can operate normally and provide a stable second voltage within the required load range.

[0069] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A voltage-regulating drive circuit, applied to a switching power supply, the switching power supply including a control unit and a power supply unit, the control unit outputting a drive signal to drive a switching transistor, characterized in that, The voltage-regulating drive circuit includes: An inductor, the first end of which is connected to the output terminal of the power supply unit, for receiving a first voltage; A voltage regulator drive module, wherein the power input terminal of the voltage regulator drive module is connected to the second terminal of the inductor, the signal input terminal of the voltage regulator drive module is connected to the drive signal output terminal of the control unit, and the output terminal of the voltage regulator drive module is connected to the control terminal of the switching transistor; The voltage regulation drive module includes a voltage conversion unit and a level conversion unit. The voltage conversion unit is used to convert the first voltage into a stable second voltage. The level conversion unit is used to receive the drive signal output by the control unit, and convert the high level of the drive signal into a level consistent with the second voltage before outputting it to the control terminal of the switching transistor.

2. The voltage-regulating drive circuit according to claim 1, characterized in that: The voltage conversion unit includes: A first switch and a second switch, wherein the first switch is connected in series between the second terminal of the inductor and the second voltage, and the second switch is connected in series between the second terminal of the inductor and the reference ground; A logic control module is used to control the complementary conduction of the first switch and the second switch to generate a switching voltage at the second terminal of the inductor connected in series with the first switch and the second switch. An electronic module is provided to obtain electrical energy from the second terminal of the inductor to generate a working power supply and a reference voltage. An energy storage capacitor is connected between the second voltage and the reference ground to stabilize the second voltage.

3. The voltage-regulating drive circuit according to claim 2, characterized in that: The logic control module includes: The voltage divider detection submodule is used to detect the second voltage and generate a feedback voltage. The comparison control submodule is used to compare the feedback voltage with the reference voltage and control the first switch and the second switch to turn on and off according to the comparison result.

4. The voltage-regulating drive circuit according to claim 3, characterized in that: The voltage divider detection submodule includes a first voltage divider resistor and a second voltage divider resistor connected in series between the second voltage and the reference ground, and the feedback voltage is generated at the common node of the first voltage divider resistor and the second voltage divider resistor; The comparison control submodule adjusts the on-time of the first switch and the second switch to make the feedback voltage approach the reference voltage, thereby stabilizing the second voltage at the target value.

5. A voltage-regulated drive circuit according to claim 2, characterized in that: The voltage conversion unit further includes a clamping diode, the cathode of which is connected to the second switch and the anode of which is connected to the reference ground, for clamping the second voltage below the clamping threshold when the second voltage exceeds the clamping threshold.

6. A voltage-regulating drive circuit according to claim 2, characterized in that: The logic control module controls the second switch to be turned on for a fixed on time, and calculates the on time of the first switch using the inductor volt-second balance principle based on the comparison result of the voltage at the common node and the reference voltage. After turning off the second switch, the first switch is turned on for a corresponding time to achieve complementary conduction between the first switch and the second switch.

7. A voltage-regulated drive circuit according to claim 2, characterized in that, The logic control module further includes a current detection submodule for detecting the current flowing through the second switch. The logic control module controls the peak current of the second switch based on the detected current to achieve adaptive conduction time and switching frequency.

8. A voltage-regulated drive circuit according to claim 1, characterized in that, The level conversion unit includes a totem pole drive module. The input terminal of the totem pole drive module is connected to the drive signal output terminal of the control unit and is used to receive the drive signal output by the control unit.

9. A switching power supply, characterized in that, include: The power stage circuit, including a rectifier and filter circuit, an electromagnetic interference filter and protection circuit, and a synchronous rectification control circuit, is used to convert the input voltage into the output voltage. The control unit is used to output drive signals; A power supply unit is used to obtain energy from the power stage circuit to generate a first voltage; It also includes a voltage-regulating drive circuit as described in any one of claims 1 to 8, wherein the first end of the inductor of the voltage-regulating drive circuit is connected to the output end of the power supply unit, the signal input end of the voltage-regulating drive circuit is connected to the drive signal output end of the control unit, and the output end of the voltage-regulating drive circuit is connected to the control end of the switching transistor in the power stage circuit, for converting the high level of the drive signal output by the control unit into a stable second voltage level to drive the switching transistor.

10. A driver chip, characterized in that, It integrates a voltage-regulating drive circuit as described in any one of claims 1 to 8.

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