Driving circuit of high-side switching tube

Abstract

The invention provides a driving circuit of a high-side switching tube, and the driving circuit of the high-side switching tube comprises a pull-up unit which carries out the pull-up of a grid potential of the high-side switching tube through a first current when a control signal is effective; the second pull-down unit is used for carrying out pull-down on the grid potential of the high-side switching tube by utilizing second current when the control signal is invalid; the pull-up unit further adjusts the first current according to the first current adjusting signal so as to adjust the starting speed of the high-side switching tube, and therefore slow starting of the high-side switching tube is achieved. According to the driving scheme of the high-side switching tube, the structure is simple, slow switching-on and switching-off of the high-side switching tube can be achieved, mistaken switching-on of the high-side switching tube can be avoided when the voltage of the input end is subjected to rapid step, and it can be ensured that no reverse current flows back to a driving circuit power source when the voltage of the output end is higher than the voltage of the input end.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, specifically to a driving circuit for a high-side switching transistor. Background Technology

[0002] In practical applications, high-side switching transistors have certain requirements for their turn-on and turn-off speeds. When the turn-on speed is too fast, the inrush current is large, which may damage the subsequent stages. When the turn-off speed is too fast, if the load has an inductance, the inductor freewheeling current will cause the output to be pulled to a negative voltage or oscillate. At the same time, during operation, if there is a rapid transient change in the input voltage of the high-side switching transistor, it will cause the high-side switching transistor to turn on falsely. Also, if the output voltage of the high-side switching transistor is shorted to a power supply with a voltage higher than the input voltage, it will cause current backflow and withstand voltage problems.

[0003] Therefore, in practical applications, the design of the driving circuit for the high-side switch is usually quite complex in order to ensure that the turn-on and turn-off speeds of the high-side switch meet the requirements, while protecting the high-side switch. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a driving circuit for a high-side switching transistor, which aims to achieve slow switching on and off of the high-side switching transistor, ensure that the high-side switching transistor is not accidentally turned on during operation, and prevent reverse current from flowing back into the power supply.

[0005] According to a first aspect of this application, a driving circuit for a high-side switching transistor is provided, comprising:

[0006] The pull-up unit pulls up the gate potential of the high-side switch transistor using a first current when the control signal is valid.

[0007] The first pull-down unit is used to establish a first discharge path between the gate and the current output terminal of the high-side switch when a transient step occurs at the current input terminal voltage of the high-side switch, so as to adjust the gate potential of the high-side switch.

[0008] Optionally, the first pull-down unit includes: a first transistor connected between the gate and the current output terminal of the high-side switch, wherein the first pull-down unit establishes the first discharge path between the gate and the current output terminal of the high-side switch by controlling the first transistor to be turned on.

[0009] When the voltage at the current input terminal of the high-side switch transistor experiences a transient step, the first pull-down unit controls the rise rate of the gate voltage of the first transistor to be lower than the rise rate of the source voltage of the first transistor, thereby controlling the first transistor to conduct for a first time when the voltage at the current input terminal of the high-side switch transistor experiences a transient step.

[0010] Optionally, the first drop-down unit further includes:

[0011] The first resistor has a first end connected to the source of the first transistor and a second end connected to the gate of the first transistor.

[0012] The first capacitor has a first terminal connected to the gate of the first transistor and a second terminal connected to the current output terminal of the high-side switching transistor.

[0013] When a transient step occurs at the current input terminal voltage of the high-side switch, the first pull-down unit uses the first resistor and the first capacitor to control the rise rate of the gate voltage of the first transistor to be lower than the rise rate of the source voltage of the first transistor.

[0014] Optionally, the pull-up unit further adjusts the first current according to the first current adjustment signal to adjust the turn-on speed of the high-side switch.

[0015] Optionally, the pull-up unit obtains the first current by mirroring the reference current;

[0016] The pull-up unit uses the first current adjustment signal to adjust the mirror ratio when mirroring the reference current and / or the magnitude of the reference current to adjust the first current.

[0017] Optionally, the driving circuit further includes:

[0018] The second pull-down unit uses a second current to pull down the gate potential of the high-side switch when the control signal is invalid.

[0019] Optionally, the second pull-down unit further adjusts the second current according to the second current adjustment signal to adjust the turn-off speed of the high-side switch.

[0020] Optionally, the driving circuit further includes:

[0021] The third pull-down unit is used to establish a second discharge path between the current output terminal of the high-side switch and the reference ground, so as to adjust the potential of the current output terminal of the high-side switch.

[0022] Optionally, the driving circuit further includes:

[0023] An anti-reverse unit is connected between the gate and the power supply terminal of the high-side switch transistor. It is used to disconnect the current path from the gate to the power supply terminal of the high-side switch transistor when the voltage at the current output terminal of the high-side switch transistor is higher than the voltage at the current input terminal of the high-side switch transistor.

[0024] Optionally, the anti-reflection unit includes:

[0025] A second transistor and a second resistor, wherein the second transistor is connected between the gate and the power supply terminal of the high-side switching transistor, and the second resistor is connected between the gate and the source of the second transistor;

[0026] Alternatively, the anti-reverse unit includes:

[0027] A diode, wherein the anode of the diode is coupled to a power supply terminal, and the cathode of the diode is coupled to the gate of the high-side switching transistor.

[0028] Optionally, the driving circuit further includes:

[0029] The first clamping unit is connected between the gate of the high-side switch and the current output terminal of the high-side switch, and is used to clamp the gate voltage of the high-side switch.

[0030] Optionally, the driving circuit further includes:

[0031] The second clamping unit is connected between the gate of the first transistor and the current output terminal of the high-side switching transistor, and is used to clamp the gate voltage of the first transistor.

[0032] Optionally, the driving circuit further includes:

[0033] An overcurrent protection unit is used to establish a third discharge path between the gate of the high-side switch and the reference ground when the current flowing through the high-side switch exceeds a preset threshold, so as to turn off the high-side switch.

[0034] Optionally, when the current flowing through the high-side switch exceeds a preset threshold, the overcurrent protection unit is further configured to establish a fourth discharge path between the gate of the first transistor and the reference ground, so as to control the first transistor to turn on and use the turned-on first transistor to accelerate the discharge rate of the gate voltage of the high-side switch.

[0035] Optionally, the pull-up unit includes:

[0036] The third transistor and the fourth transistor form a current mirror structure, and the branch where the third transistor is located receives the reference current, while the branch where the fourth transistor is located outputs the first current.

[0037] A fifth transistor and a sixth transistor are connected in series with the third transistor. The control terminal of the fifth transistor receives a bias voltage, and the control terminal of the sixth transistor receives the control signal.

[0038] The seventh transistor is connected in series with the fourth transistor, and the control terminal of the seventh transistor receives a bias voltage.

[0039] Optionally, the second drop-down unit includes:

[0040] An eighth transistor and a third resistor are connected in series between the gate of the high-side switch and the reference ground. The control terminal of the eighth transistor receives the inverted signal of the control signal.

[0041] Optionally, the overcurrent protection unit includes:

[0042] A ninth transistor and a first current source are connected in series between the gate of the high-side switch and a reference ground. The control terminal of the ninth transistor receives an overcurrent protection signal.

[0043] Optionally, the overcurrent protection unit further includes:

[0044] A tenth transistor and a second current source are connected in series between the gate of the first transistor and a reference ground. The control terminal of the tenth transistor receives an overcurrent protection signal.

[0045] The beneficial effects of this application include at least the following:

[0046] The high-side switch driving scheme provided in this application uses a first current to pull up the gate potential of the high-side switch when the control signal is valid. During this process, the first current adjustment signal can also be used to adjust the turn-on speed of the high-side switch by adjusting the first current. This allows the high-side switch to be turned on slowly by reducing the first current. Compared with existing high-side driving schemes, the scheme in this application can flexibly adjust the turn-on speed of the high-side switch and control the high-side switch to turn on slowly, which can reduce the surge current when the high-side switch is turned on and avoid damage to the subsequent circuits.

[0047] In a further preferred embodiment, during the process of the control signal being invalid and the gate potential of the high-side switch being pulled down using the second current, the turn-on speed of the high-side switch is also adjusted by adjusting the second current using the second current adjustment signal. This allows the high-side switch to be slowly turned off by reducing the second current, which helps to avoid negative output voltage or oscillation under inductive loads.

[0048] In a further preferred embodiment, when the voltage at the current input terminal of the high-side switch transistor undergoes a transient step, the first pull-down unit establishes a first discharge path between the gate of the high-side switch transistor and its current output terminal to adjust the gate potential of the high-side switch transistor. This can prevent the high-side switch transistor from generating a large instantaneous current due to excessive turn-on degree at the moment of the step, and also prevent voltage overshoot at the current output terminal of the high-side switch transistor in the disabled state.

[0049] In a further preferred embodiment, the anti-reverse unit is configured to disconnect the current path from the gate of the high-side switch to the power supply terminal when the voltage at the current output terminal of the high-side switch is higher than the voltage at its current input terminal, thereby blocking the reverse current flowing into the power supply terminal of the drive circuit.

[0050] In a further preferred embodiment, a clamping unit is provided between the gate and source of the high-side switch to protect the gate voltage of the high-side switch.

[0051] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit this application. Attached Figure Description

[0052] Figure 1 This diagram shows a structural block diagram of a switching converter provided according to an embodiment of this application;

[0053] Figure 2 Show Figure 1 A schematic diagram of one implementation of the drive circuit;

[0054] Figure 3 A schematic diagram illustrating an embodiment of the driving circuit provided according to the first embodiment of this application is shown;

[0055] Figure 4 A schematic diagram illustrating an embodiment of the driving circuit provided according to the second embodiment of this application is shown;

[0056] Figure 5 A schematic diagram illustrating an embodiment of the driving circuit provided according to the third embodiment of this application is shown;

[0057] Figure 6 A schematic diagram illustrating an embodiment of the driving circuit provided according to the fourth embodiment of this application is shown;

[0058] Figure 7 A schematic diagram illustrating an embodiment of the driving circuit provided according to the fifth embodiment of this application is shown;

[0059] Figure 8 A schematic diagram illustrating an embodiment of the driving circuit provided according to the sixth embodiment of this application is shown;

[0060] Figure 9A schematic diagram illustrating an embodiment of the driving circuit provided according to the seventh embodiment of this application is shown;

[0061] Figure 10 A schematic diagram illustrating an embodiment of the driving circuit provided according to the eighth embodiment of this application is shown;

[0062] Figure 11 A schematic flowchart of a driving method for a high-side switching transistor according to an embodiment of this application is shown. Detailed Implementation

[0063] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application may be implemented in various forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0064] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0065] In the description of this application, the words "exemplary" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments. "And / or" in this document describes a relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. "Coupling" describes a connection relationship between related objects. For example, A and B are coupled, which can indicate a direct connection between A and B, or an indirect connection between A and B through other devices / units / modules. "Multiple" refers to two or more. Furthermore, to facilitate a clear description of the technical solutions of the embodiments of this application, the terms "first," "second," etc., are used to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and that "first," "second," etc., do not necessarily imply differences.

[0066] In addition, the same reference numerals in the figures indicate the same or similar structures, so repeated descriptions of them will be omitted. That is, the various parts in this specification are described in a combination of parallel and progressive manner. Each part focuses on the differences from other parts, and the same or similar parts between the various parts can be referred to each other.

[0067] Figure 1 The diagram shows a structural block diagram of a switching converter provided in an embodiment of this application. The switching converter can realize voltage conversion, such as boost, buck, buck-boost, etc., and can be understood as a voltage converter or power converter.

[0068] like Figure 1 As shown, the switching converter 100 includes: a high-side switching transistor MP and a low-side rectifier unit (hereinafter referred to as the rectifier unit) 110 connected in series, as well as a control circuit 120 and a drive circuit 130.

[0069] The first terminal (current input terminal) of the high-side switch MP is connected to the input voltage VIN. The second terminal (current output terminal) of the high-side switch MP is electrically connected to the first terminal (current input terminal) of the rectifier unit 110, and the second terminal (current output terminal) of the rectifier unit 110 is grounded. The common connection point between the high-side switch MP and the rectifier unit 110 is the switching terminal SW of the switching converter 100, i.e., the voltage output terminal. The control terminal (gate) of the high-side switch MP is connected to the corresponding drive signal Vgs1.

[0070] In some embodiments, the rectifier unit 110 is a low-side switch, and the control terminal (i.e., the gate) of the low-side switch is also connected to the corresponding drive signal; in other embodiments, the rectifier unit 110 is a diode.

[0071] Of course, the switching converter can also be called a power MOS circuit, and the high-side switching transistor can also be called a high-side switching transistor, high-side power transistor, high-side power transistor, or other names, which are not limited in this disclosure. Optionally, the high-side switching transistor MP can be an NMOS transistor or a PMOS transistor. When both high-side switching transistors MP are NMOS transistors, the current input terminal of the high-side switching transistor MP is its drain, connected to the input voltage VIN, and the current output terminal of the high-side switching transistor MP is its source, connected to the switching terminal SW. When the high-side switching transistor MP is a PMOS transistor, the current input terminal of the high-side switching transistor MP is its source, connected to the input voltage VIN, and the current output terminal of the high-side switching transistor MP is its drain, connected to the switching terminal SW.

[0072] When the rectifier unit 110 is a low-side switch, the drive signals connected to the control terminals of the high-side switch MP and the low-side switch are complementary, thereby controlling one of the two switches to be on while the other is off. For example, the high-side switch is on while the low-side switch is off, or the high-side switch is off while the low-side switch is on. In this way, by continuously changing the complementary drive signals, the output voltage of the switch terminal SW is controlled to change.

[0073] The control circuit 120 is used to provide the control signal PWM. The specific structure of the control circuit 120 can be understood by referring to the prior art, and will not be described in detail in this application.

[0074] The driver circuit 130 converts the control signal PWM into a corresponding drive signal Vgs1 and provides it to the gate of the high-side switch MP, thereby driving the high-side switch MP to turn on or off. When the high-side switch MP needs to be turned on, the parasitic capacitance between the gate and source of the driven high-side switch MP (denoted as C)... GS The charging speed determines the turn-on speed of the high-side switch MP, and the turn-on speed of MP reflects the driving speed of the drive circuit. However, in practical applications, the gate voltage of the high-side switch MP is often also affected by the parasitic capacitance between its gate and drain (denoted as C). GD The impact of ).

[0075] refer to Figure 2 , Figure 2 It shows Figure 1 A schematic diagram of one implementation of the driving circuit. Figure 2 In the example shown, the driving circuit 130 includes transistors M21 and M22 connected in series between the power supply terminal VCAP and the switching terminal SW. Transistors M21 and M22 form an inverter driving structure to charge and discharge the gate of the high-side switch MP under the control of the control signal PWM, thereby controlling the turn-on and turn-off of the high-side switch MP. The dimensions of transistors M21 and M22 determine the charging and discharging speed.

[0076] Because high-side switching transistors (MPs) are typically large in size to achieve low on-resistance, their gate-drain parasitic capacitance C... GD It is also relatively large; when the input voltage VIN jumps rapidly, the parasitic capacitance C... GD The coupling effect causes the gate voltage of the high-side switch MP to rise rapidly, resulting in a high gate-source voltage difference for the high-side switch MP. This leads to a large instantaneous current generated by the high-side switch MP, affecting subsequent stages. Furthermore, when the switch terminal SW is connected to a power supply much higher than the input voltage VIN, reverse current will flow through transistors M21 and M22, causing a voltage withstand issue in the drive circuit 130.

[0077] Based on the above reasons, this application further proposes an optimized driving scheme. This driving circuit has a simple structure and can achieve slow turn-on and turn-off of the high-side switch MP; and when the input voltage VIN jumps rapidly, it can avoid the high-side switch MP from being affected by parasitic capacitance C. GD It can prevent accidental activation due to coupling; and when the voltage at the switching terminal SW is higher than the input voltage VIN, it can effectively protect the gate voltage of the high-side switching transistor MP, and prevent reverse current from flowing back to the power supply of the drive circuit.

[0078] It should be noted that the driving circuit 130 disclosed in the embodiments of this application is not limited to driving the high-side switching transistor in the switching converter. The solution of this application can also be applied to other circuit applications with high-side switching transistors.

[0079] refer to Figures 3 to 10 In embodiments of this application, the driving circuit 130 includes at least: a pull-up unit 310 and a second pull-down unit 320 connected to the gate of the high-side switch MP. The pull-up unit 310 is used to pull up the gate potential of the high-side switch MP using a first current when the control signal PWM is valid. The second pull-down unit 320 is used to pull down the gate potential of the high-side switch MP using a second current when the control signal PWM is invalid. The pull-up unit 310 also adjusts the first current according to a first current adjustment signal to adjust the turn-on speed of the high-side switch MP.

[0080] It should be noted that the effective level state of the control signal PWM is either a high level state or a low level state, while the ineffective level state of the control signal PWM is either a high level state or a low level state, depending on the transistor type of the high-side switch MP. For example, when the high-side switch MP is an NMOS transistor, the effective level state of the control signal PWM is a high level state, and the ineffective level state of the control signal PWM is a low level state.

[0081] The pull-up unit 310 obtains the first current by mirroring the reference current I1. Optionally, the pull-up unit 310 can adjust the mirroring ratio of the reference current I1 and / or adjust the magnitude of the reference current I1 to adjust the first current using the first current adjustment signal. In this embodiment, a smaller first current can be used to achieve the slow turn-on of the high-side switch MP by setting a smaller reference current I1 and / or a smaller mirroring ratio.

[0082] exist Figure 3 and Figure 10In the illustrated embodiment, the pull-up unit 310 includes transistors M1, M2, M3, M4, and M7. Transistors M1 and M2 form a current mirror structure, and the branch containing transistor M1 receives a reference current I1, while the branch containing transistor M2 outputs a first current. Transistors M3 and M7 are connected in series with transistor M1. The control terminal of transistor M3 receives a bias voltage VBN, and the control terminal of transistor M7 receives a control signal PWM. Transistor M4 is connected in series with transistor M2, and the control terminal of transistor M4 receives a bias voltage VBN.

[0083] In practice, when mirroring the reference current I1, the mirror ratio is expressed as the width-to-length ratio of transistor M1 and transistor M2. When it is necessary to adjust the mirror ratio, the first current adjustment signal can adjust the width-to-length ratio of transistor M1 and transistor M2, for example, by adjusting the number of transistors connected in parallel with transistor M1 and / or adjusting the number of transistors connected in parallel with transistor M2.

[0084] Optionally, the reference current I1 can be provided by a constant current source connected in series with transistors M1, M3, and M7. When it is necessary to adjust the magnitude of the reference current I1, the first current adjustment signal can adjust the magnitude of the reference current I1 by switching constant current sources of different specifications. Alternatively, the reference current I1 can be provided by a resistive element connected in series with transistors M1, M3, and M7. When it is necessary to adjust the magnitude of the reference current I1, the first current adjustment signal can adjust the magnitude of the reference current I1 by the effective resistance value of the resistive element.

[0085] When the drive circuit 130 is used in a high-voltage scenario, transistors M3, M4, and M7 are all high-voltage transistors; and when the drive circuit 130 is used in a low-voltage scenario, transistors M3 and M4 can be omitted.

[0086] It should be noted that by setting a first current adjustment signal to adjust the first current, flexible control of the turn-on speed of the high-side switch MP can be achieved. Of course, in some embodiments, a fixed, small reference current I1 and / or a small mirror ratio can also be preset to directly achieve the slow turn-on of the high-side switch MP, thus eliminating the need to set a first current adjustment signal.

[0087] The second pull-down unit 320 also adjusts the second current according to the second current adjustment signal to regulate the turn-off speed of the high-side switch MP. In this embodiment, a slow turn-off of the high-side switch MP can be achieved by setting a smaller second current.

[0088] exist Figure 4 and Figure 10In the embodiment shown, the second pull-down unit 320 includes an inverter INV1, a transistor M8, and a resistor R3. The transistor M8 and the resistor R3 are connected in series between the gate of the high-side switch MP and the reference ground. The control terminal of the transistor M8 receives the inverted signal of the control signal PWM through the inverter INV1.

[0089] Optionally, when the driving circuit 130 is used in a high-voltage scenario, transistor M8 is a high-voltage transistor; and when the driving circuit 130 is used in a low-voltage scenario, transistor M8 is either a high-voltage transistor or a low-voltage transistor.

[0090] In these embodiments, the second current is the current through resistor R3, meaning the second current is limited by the resistance value of resistor R3. When it is necessary to adjust the magnitude of the second current, the second current adjustment signal can be adjusted by the effective resistance value of resistor R3. In other embodiments, resistor R3 can also be replaced with a constant current source. In this case, when it is necessary to adjust the magnitude of the second current, the second current adjustment signal can be adjusted by switching between constant current sources of different specifications.

[0091] It should be noted that by setting a second current adjustment signal to regulate the second current, flexible control of the turn-off speed of the high-side switch MP can be achieved. Of course, in some embodiments, a fixed, smaller second current can also be preset to directly achieve slow turn-off control of the high-side switch MP, thus eliminating the need to set a second current adjustment signal.

[0092] In some further embodiments, reference is made to Figures 5-10 The driving circuit 130 further includes a first pull-down unit 330 connected to the gate and current output terminal of the high-side switch MP. The first pull-down unit 330 is used to establish a first discharge path between the gate and current output terminal of the high-side switch MP when a transient step (or fast step) occurs at the current input terminal voltage of the high-side switch MP, so as to adjust the gate potential of the high-side switch MP and avoid transient current generated by excessive turn-on degree of the high-side switch MP.

[0093] In specific implementation, refer to Figure 5 The first pull-down unit 330 includes a transistor M6 connected between the gate and the current output terminal of the high-side switch MP. The first pull-down unit 330 establishes a first discharge path between the gate and the current output terminal of the high-side switch MP by controlling the transistor M6 to turn on. When a transient step occurs at the current input terminal voltage of the high-side switch MP, the first pull-down unit 330 is configured, for example, to control the rise rate of the gate voltage of the transistor 330 to be lower than the rise rate of the source voltage of the transistor M6, thereby controlling the transistor M6 to turn on for a first time when a transient step occurs at the current input terminal voltage of the high-side switch MP.

[0094] exist Figure 5 In the illustrated embodiment, the first pull-down unit 330 further includes, for example, a resistor R2 and a capacitor C1. When a transient step occurs in the current input voltage of the high-side switch MP, the first pull-down unit 330 uses the resistor R2 and capacitor C1 to control the rise rate of the gate voltage of transistor M6 to be lower than the rise rate of the source voltage of the first transistor. The first end of the resistor R2 is connected to the source of transistor M6, and the second end of the resistor R2 is connected to the gate of transistor M6. The first end of the capacitor C1 is connected to the gate of transistor M6, and the second end of the capacitor C1 is connected to the current output of the high-side switch MP. It can be understood that by setting the resistor R2 and capacitor C1, automatic turn-on and turn-off control of transistor M6 can be achieved without additional control signals.

[0095] In some further embodiments, reference is made to Figures 6-10 The driving circuit 130 further includes a third pull-down unit connected to the current output terminal of the high-side switch MP. This third pull-down unit is used to establish a second discharge path between the current output terminal of the high-side switch MP and the reference ground, thereby adjusting the potential of the current output terminal of the high-side switch MP. Figure 6 In the illustrated embodiment, the third pull-down unit is implemented by resistor R4. Of course, in other embodiments, the third pull-down unit may also be implemented by a constant current source or a transistor, and this application does not impose strict limitations on this.

[0096] In some further embodiments, reference is made to Figures 7-10 The driving circuit 130 further includes an overcurrent protection unit 340 connected to the gate of the high-side switch MP. The overcurrent protection unit 340 is used to establish a third discharge path between the gate of the high-side switch MP and the reference ground when the current flowing through the high-side switch MP exceeds a preset threshold, so as to turn off the high-side switch MP and realize overcurrent protection for the high-side switch MP.

[0097] exist Figure 7 In the illustrated embodiment, the overcurrent protection unit 340 includes a transistor M9 and a current source I2 connected in series between the gate of the high-side switch MP and a reference ground. The control terminal of the transistor M9 receives an overcurrent protection signal CL_EN. The overcurrent protection signal CL_EN is active when the current flowing through the high-side switch MP exceeds a preset threshold.

[0098] Optionally, transistor M9 is a high-voltage transistor in high-voltage applications and a high-voltage transistor or a low-voltage transistor in low-voltage applications.

[0099] Preferably, the driving circuit 130 further includes a first clamping unit connected between the gate of the high-side switch MP and the current output terminal of the high-side switch MP, the first clamping unit being used to clamp the gate voltage of the high-side switch MP. Figure 7 In the illustrated embodiment, the first clamping unit includes, for example, a clamping diode D1.

[0100] Furthermore, in Figure 8 In the embodiment shown, when the current flowing through the high-side switch MP exceeds a preset threshold, the overcurrent protection unit 340 is also used to establish a fourth discharge path between the gate of the transistor M6 and the reference ground to control the transistor M6 to turn on, and use the turned-on transistor M6 to accelerate the discharge speed of the gate voltage of the high-side switch MP, thereby accelerating the turn-off speed of the high-side switch MP, which is beneficial to achieving better overcurrent protection.

[0101] exist Figure 8 and Figure 10 In the embodiment shown, the overcurrent protection unit 340 includes, in addition to transistor M9 and current source I2, transistor M10 and current source I3 connected between the gate of transistor M6 and reference ground, and the control terminal of transistor M10 receives the overcurrent protection signal CL_EN.

[0102] Optionally, transistor M10 is a high-voltage transistor in high-voltage applications and a high-voltage transistor or a low-voltage transistor in low-voltage applications.

[0103] Preferably, the driving circuit 130 further includes a second clamping unit connected between the gate of transistor M6 and the current output terminal of the high-side switch MP, the second clamping unit being used to clamp the gate voltage of transistor M6. Figure 8 In the illustrated embodiment, the second clamping unit includes, for example, a clamping diode D2.

[0104] In some further embodiments, reference is made to Figure 9 and Figure 10 The driving circuit 130 further includes an anti-reverse unit 350 connected between the gate of the high-side switch MP and the power supply terminal VCAP of the driving circuit 130. The anti-reverse unit 350 is used to disconnect the current path from the gate of the high-side switch MP to the power supply terminal VCAP when the voltage at the current output terminal of the high-side switch MP is higher than the voltage at the current input terminal of the high-side switch MP.

[0105] exist Figure 9 and Figure 10In the illustrated embodiment, the anti-reverse unit 350 includes a transistor M5 and a resistor R1. The transistor M5 is coupled between the gate of the high-side switching transistor MP and the power supply terminal VCAP, and the resistor R1 is connected between the gate and source of the transistor M5. Optionally, the transistor M5 is a high-voltage transistor in high-voltage applications and a high-voltage transistor or a low-voltage transistor in low-voltage applications.

[0106] Of course, in other embodiments, the anti-reverse unit 350 can also be implemented by a device with unidirectional conduction properties, such as a diode. In this case, the anode of the diode is coupled to the power supply terminal VCAP, and the cathode of the diode is coupled to the gate of the high-side switch MP.

[0107] by Figure 10 Taking the illustrated embodiment as an example, the working principle of the driving circuit 130 disclosed in this application is as follows:

[0108] During operation, when the control signal PWM flips from an invalid state to an active state, transistor M7 in pull-up unit 310 is turned on. Transistors M1 and M2 mirror the reference current I1 into a first current at a certain ratio and transmit it to the gate of the high-side switch MP to charge the gate of the high-side switch MP. Since the magnitude of the first current charging the gate of the high-side switch MP can be adjusted by adjusting the mirror ratio of transistors M1 and M2 and / or the magnitude of the reference current I1, this application can use pull-up unit 310 to easily and conveniently realize the slow turn-on of the high-side switch MP.

[0109] During normal operation of the high-side switch MP, the source voltage of transistor M6 in the first pull-down unit 330 is equal to its gate voltage, causing transistor M6 to be in the off state. When the input voltage VIN connected to the current input terminal of the high-side switch MP increases rapidly by a step, due to the large size of the high-side switch MP, its parasitic capacitance between the gate and drain is large. GD Based on the parasitic capacitance C GDThe coupling effect causes the gate voltage of the high-side switch MP and the source voltage of transistor M6 to rise rapidly. However, the RC network formed by resistor R2 and capacitor C1 causes the gate voltage of transistor M6 to rise more slowly. During this process, transistor M6 is in the on state, thus establishing a discharge path between the gate of the high-side switch MP and the switching terminal SW to discharge the gate of the high-side switch MP. Furthermore, through the combined action of transistor M6, resistor R2, and capacitor C1 in the first pull-down unit 330, the large transient current generated by the high-side switch MP being turned on too much during the instantaneous step of the input voltage VIN is avoided. At the same time, the first pull-down unit 330 can also effectively prevent the high-side switch MP from turning on when the driving circuit 130 is not enabled and the input voltage VIN has a transient step, thus avoiding a large overshoot voltage at the switching terminal SW. In addition, the presence of resistor R4 will further discharge the voltage at the switching terminal SW.

[0110] During normal operation of the high-side switch MP, if the voltage at the switching terminal SW suddenly becomes significantly higher than the input voltage VIN, clamping diodes D1 and D2 can provide clamping protection for the high-side switch MP and transistor M6, respectively. Simultaneously, the reverse current protection unit 350 can disconnect the current path from the gate of the high-side switch MP to the power supply terminal VCAP (e.g., by turning off transistor M5 in the reverse current protection unit 350), thereby preventing reverse current from flowing to the power supply terminal VCAP.

[0111] When a high current is detected in the high-side switch MP, such as when the current flowing through MP exceeds a preset threshold, the overcurrent protection signal CL_EN will flip from an inactive state to an active state. This controls transistors M9 and M10 to conduct, causing the bias currents provided by current sources I2 and I3 to discharge the gates of the high-side switch MP and M6 respectively, pulling them to the reference ground potential, thereby turning off the high-side switch MP and achieving overcurrent protection for it. During this process, clamping diode D1 clamps the gate voltage of the high-side switch MP, ensuring that its gate voltage is at most one forward voltage drop of clamping diode D1 lower than its source voltage, thus protecting the gate of the high-side switch MP. Similarly, clamping diode D2 clamps the gate voltage of transistor M6 during this process, ensuring that its gate voltage is at most one forward voltage drop of clamping diode D2 lower than the switching terminal SW, thus protecting the gate of transistor M6.

[0112] When the drive circuit 130 is released from overcurrent protection, the overcurrent protection signal CL_EN flips from an active state to an inactive state, controlling transistors M9 and M10 to turn off. At this time, transistor M6 can still respond to transient changes in the input voltage VIN.

[0113] When the control signal PWM flips from an active state to an inactive state, the gate voltage of the high-side switch MP is discharged through the second pull-down unit 320 (such as the branch where resistor R3 and transistor M8 are located). By changing the magnitude of the second current provided by the second pull-down unit 320 (such as changing the magnitude of resistor R3), the discharge rate of the gate voltage of the high-side switch MP can be adjusted. Therefore, this application can use the second pull-down unit 320 to easily and conveniently realize the slow turn-off of the high-side switch MP.

[0114] Furthermore, embodiments of this application also provide a driving method for a high-side switching transistor, which can be applied to the aforementioned... Figures 3-10 In any embodiment of the driving circuit 130 disclosed herein, in specific implementation, refer to Figure 11 The driving method includes performing the following steps:

[0115] Step 111: When the control signal is valid, the gate potential of the high-side switch is pulled up using the first current. The process of pulling up the gate potential of the high-side switch using the first current further includes: adjusting the first current according to the first current adjustment signal to adjust the turn-on speed of the high-side switch.

[0116] Step 112: When the control signal is invalid, the gate potential of the high-side switch is pulled down using the second current.

[0117] In step 111, for example, the first current can be obtained by mirroring the reference current. At this time, the first current adjustment signal adjusts the first current by adjusting the mirror ratio when mirroring the reference current and / or the magnitude of the reference current.

[0118] Furthermore, in step 112, when using the second current to pull down the gate potential of the high-side switch, the method further includes: adjusting the second current according to the second current adjustment signal to adjust the turn-off speed of the high-side switch.

[0119] In some embodiments, the driving method further includes: when a transient step occurs at the current input terminal voltage of the high-side switch, establishing a first discharge path between the gate of the high-side switch and its current output terminal to adjust the gate potential of the high-side switch.

[0120] In some embodiments, the driving method further includes: establishing a second discharge path between the current output terminal of the high-side switch and a reference ground to adjust the potential of the current output terminal of the high-side switch. Exemplarily, a first transistor can be disposed between the gate and the current output terminal of the high-side switch. A first discharge path is established between the gate and the current output terminal of the high-side switch by controlling the first transistor to conduct. When a transient step occurs at the current input terminal voltage of the high-side switch, the rise rate of the gate voltage of the first transistor is controlled to be lower than the rise rate of the source voltage of the first transistor, thereby controlling the first transistor to conduct for a first time when a transient step occurs at the current input terminal voltage of the high-side switch.

[0121] In some embodiments, the driving method further includes: disconnecting the current path from the gate of the high-side switch to the power supply when the voltage at the current output terminal of the high-side switch is higher than the voltage at the current input terminal of the high-side switch.

[0122] In some embodiments, the driving method further includes: when the current flowing through the high-side switch exceeds a preset threshold, establishing a third discharge path between the gate of the high-side switch and a reference ground to turn off the high-side switch.

[0123] Furthermore, when the current flowing through the high-side switch exceeds a preset threshold, a fourth discharge path is established between the gate of the first transistor and the reference ground to control the first transistor to turn on, and the turned-on first transistor is used to accelerate the discharge speed of the gate voltage of the high-side switch.

[0124] In some embodiments, the driving method further includes clamping the gate voltage of the high-side switch.

[0125] In some embodiments, the driving method further includes clamping the gate voltage of the first transistor.

[0126] It should be noted that the specific implementation of each step in the driving method described above can be found in the embodiment of the driving circuit 130 disclosed in any of the foregoing embodiments, and will not be repeated here.

[0127] In summary, the driving scheme for the high-side switching transistor disclosed in the embodiments of this application has at least the following beneficial effects:

[0128] 1. It can achieve slow turn-on and slow turn-off control of the high-side switching transistor;

[0129] 2. When the input voltage jumps rapidly, it can avoid the problem of large instantaneous current generated by the high-side switching transistor due to the coupling of the gate-drain parasitic capacitance of the high-side switching transistor, and avoid overshoot voltage at the switching terminal when it is not enabled.

[0130] 3. It can block the reverse current flowing into the power supply terminal of the drive circuit when the voltage at the current output terminal (i.e., the switching terminal) of the high-side switching transistor is higher than the voltage at its current input terminal (i.e., the input voltage), and at the same time provide clamping protection for the gate of the high-side switching transistor.

[0131] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating this application and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A driving circuit for a high-side switching transistor, comprising: The pull-up unit pulls up the gate potential of the high-side switch transistor using a first current when the control signal is valid. The first pull-down unit is used to establish a first discharge path between the gate and the current output terminal of the high-side switch when a transient step occurs at the current input terminal voltage of the high-side switch, so as to adjust the gate potential of the high-side switch.

2. The driving circuit according to claim 1, wherein, The first pull-down unit includes a first transistor connected between the gate and the current output terminal of the high-side switching transistor. The first pull-down unit establishes the first discharge path between the gate and the current output terminal of the high-side switching transistor by controlling the first transistor to be turned on. When the voltage at the current input terminal of the high-side switch transistor experiences a transient step, the first pull-down unit controls the rise rate of the gate voltage of the first transistor to be lower than the rise rate of the source voltage of the first transistor, thereby controlling the first transistor to conduct for a first time when the voltage at the current input terminal of the high-side switch transistor experiences a transient step.

3. The driving circuit according to claim 2, wherein, The first pull-down unit also includes: The first resistor has a first end connected to the source of the first transistor and a second end connected to the gate of the first transistor. The first capacitor has a first terminal connected to the gate of the first transistor and a second terminal connected to the current output terminal of the high-side switching transistor. When a transient step occurs at the current input terminal voltage of the high-side switch, the first pull-down unit uses the first resistor and the first capacitor to control the rise rate of the gate voltage of the first transistor to be lower than the rise rate of the source voltage of the first transistor.

4. In the driving circuit according to claim 1, the pull-up unit further adjusts the first current according to the first current adjustment signal to adjust the turn-on speed of the high-side switch.

5. The driving circuit according to claim 4, wherein, The pull-up unit obtains the first current by mirroring the reference current; The pull-up unit uses the first current adjustment signal to adjust the mirror ratio when mirroring the reference current and / or the magnitude of the reference current to adjust the first current.

6. The driving circuit according to claim 1, wherein, The driving circuit also includes: The second pull-down unit uses a second current to pull down the gate potential of the high-side switch when the control signal is invalid.

7. The driving circuit according to claim 6, wherein, The second pull-down unit also adjusts the second current according to the second current adjustment signal to adjust the turn-off speed of the high-side switch.

8. The driving circuit according to claim 1, wherein, The driving circuit also includes: The third pull-down unit is used to establish a second discharge path between the current output terminal of the high-side switch and the reference ground, so as to adjust the potential of the current output terminal of the high-side switch.

9. The driving circuit according to claim 1, wherein, The driving circuit also includes: An anti-reverse unit is connected between the gate and the power supply terminal of the high-side switch transistor. It is used to disconnect the current path from the gate to the power supply terminal of the high-side switch transistor when the voltage at the current output terminal of the high-side switch transistor is higher than the voltage at the current input terminal of the high-side switch transistor.

10. The driving circuit according to claim 9, wherein, The anti-countermeasures unit includes: A second transistor and a second resistor, wherein the second transistor is connected between the gate and the power supply terminal of the high-side switching transistor, and the second resistor is connected between the gate and the source of the second transistor; Alternatively, the anti-reverse unit includes: A diode, wherein the anode of the diode is coupled to a power supply terminal, and the cathode of the diode is coupled to the gate of the high-side switching transistor.

11. The driving circuit according to claim 2, wherein, The driving circuit also includes: An overcurrent protection unit is used to establish a third discharge path between the gate of the high-side switch and the reference ground when the current flowing through the high-side switch exceeds a preset threshold, so as to turn off the high-side switch.

12. The driving circuit according to claim 11, wherein, When the current flowing through the high-side switch exceeds a preset threshold, the overcurrent protection unit is also used to establish a fourth discharge path between the gate of the first transistor and the reference ground to control the first transistor to turn on, and to use the turned-on first transistor to accelerate the discharge rate of the gate voltage of the high-side switch.

13. The driving circuit according to claim 1 or 11, wherein, The driving circuit also includes: The first clamping unit is connected between the gate of the high-side switch and the current output terminal of the high-side switch, and is used to clamp the gate voltage of the high-side switch.

14. The driving circuit according to claim 2 or 12, wherein, The driving circuit also includes: The second clamping unit is connected between the gate of the first transistor and the current output terminal of the high-side switching transistor, and is used to clamp the gate voltage of the first transistor.

15. The driving circuit according to any one of claims 1-5, wherein, The pull-up unit includes: The third transistor and the fourth transistor form a current mirror structure, and the branch where the third transistor is located receives the reference current, while the branch where the fourth transistor is located outputs the first current. A fifth transistor and a sixth transistor are connected in series with the third transistor. The control terminal of the fifth transistor receives a bias voltage, and the control terminal of the sixth transistor receives the control signal. The seventh transistor is connected in series with the fourth transistor, and the control terminal of the seventh transistor receives a bias voltage.

16. The driving circuit according to claim 6 or 7, wherein, The second drop-down unit includes: An eighth transistor and a third resistor are connected in series between the gate of the high-side switch and the reference ground. The control terminal of the eighth transistor receives the inverted signal of the control signal.

17. The driving circuit according to claim 11, wherein, The overcurrent protection unit includes: A ninth transistor and a first current source are connected in series between the gate of the high-side switch and a reference ground. The control terminal of the ninth transistor receives an overcurrent protection signal.

18. The driving circuit according to claim 12, wherein, The overcurrent protection unit further includes: A tenth transistor and a second current source are connected in series between the gate of the first transistor and a reference ground. The control terminal of the tenth transistor receives an overcurrent protection signal.

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