A drive circuit

Abstract

This invention discloses a driving circuit, relating to the field of electronic circuit technology. By setting a variable-resistance first turn-off control circuit at the driving terminal of a first switching transistor, and using a current detection circuit to detect the current in the branch containing the first switching transistor, a soft-turn-off control module, based on the turn-off signal at the driving signal input terminal and the signal from the current detection circuit, gradually changes the resistance value of the first turn-off control circuit when there is current during the first switch transistor's turn-off. This causes the voltage at the driving terminal of the first switching transistor to change slowly at the beginning of the turn-off, preventing sudden changes in discharge current from causing induced electromotive force in the parasitic inductance at the power supply terminal and resulting in voltage spikes. As the resistance value of the variable resistor circuit decreases until it reaches a first target resistance value, the first switching transistor is finally completely turned off. This achieves a driving circuit with soft-turn-off functionality, which can effectively suppress voltage spikes generated at the power supply pins when the power switching device is turned off.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and more particularly to a driving circuit. Background Technology

[0002] With the widespread application of power switching devices in high-speed switching processes, the problem of transient voltage spikes caused by circuit parasitic parameters has become increasingly prominent. Specifically, the rapid turn-off of a power switch causes a sudden change in the current flowing through the parasitic inductance of the power supply circuit, which in turn generates an induced voltage spike on the power supply pin. If this spike voltage is too high, it can easily cause irreversible damage to the power switching device and even the drive circuit, seriously threatening the reliability of the system.

[0003] Therefore, how to suppress the voltage spikes generated at the power supply pins when the power switch is turned off is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] The present invention provides a driving circuit to at least solve the problem of voltage spikes generated at the power supply pins when power switching devices are turned off in the related art.

[0005] To solve the above-mentioned technical problems, the present invention provides a driving circuit, including a first switching transistor and a first control circuit; The first switching transistor is connected between the power supply terminal and the voltage output terminal; The first control circuit includes a current detection circuit, a soft shutdown control module, and a first sub-drive circuit; The first sub-driving circuit is located between the power supply terminal and the reference low-level terminal. The first sub-driving circuit includes a first turn-on control circuit and a first turn-off control circuit connected in series. The connection point of the first turn-on control circuit and the first turn-off control circuit is connected to the driving terminal of the first switching transistor. The first turn-off control circuit is a variable resistor circuit. The input terminal of the current detection circuit is located in the branch where the first switching transistor is located. The first input terminal of the soft shutdown control module is connected to the output terminal of the current detection circuit. The second input terminal of the soft shutdown control module is connected to the drive signal input terminal of the first switching transistor. The output terminal of the soft shutdown control module is connected to the resistance adjustment terminal of the first shutdown control circuit. The soft shutdown control module is used to respond to the shutdown signal at the drive signal input terminal and the first signal of the current detection circuit to control the resistance value of the first shutdown control circuit to decrease from the initial resistance value until the first target resistance value is reached.

[0006] Optionally, the soft shutdown control module is further configured to control the resistance value of the first shutdown control circuit to maintain a second target resistance value in response to the shutdown signal at the drive signal input terminal and the second signal of the current detection circuit, wherein the second target resistance value is less than the initial resistance value.

[0007] Optionally, the soft shutdown control module includes a short pulse control circuit and a switch control circuit; The first input terminal of the short pulse control circuit is connected to the output terminal of the current detection circuit, the second input terminal of the short pulse control circuit is connected to the drive signal input terminal of the first switching transistor, the output terminal of the short pulse control circuit is connected to the input terminal of the switch control circuit, and the output terminal of the switch control circuit is connected to the resistance adjustment terminal of the first turn-off control circuit.

[0008] Optionally, the first shutdown control circuit includes a plurality of second switching transistors connected in parallel between the driving terminal of the first switching transistor and the second conductive terminal of the first switching transistor. The soft shutdown control module controls the resistance value of the first shutdown control circuit to decrease from its initial resistance value until it reaches the first target resistance value, including: The soft shutdown control module controls the first shutdown control circuit to gradually shut down at least one of the second switching transistors that are in a conducting state, so that the variable resistor circuit reduces from the initial resistance value to the first target resistance value.

[0009] Optionally, the first shutdown control circuit includes a first branch and a second branch connected in series, the first branch includes a third switch and a first resistor connected in parallel, and the second branch includes a fourth switch. The driving terminal of the third switch is connected to the soft shutdown control module, and the driving terminal of the fourth switch is connected to the driving signal input terminal. The soft shutdown control module controls the resistance value of the first shutdown control circuit to decrease from its initial resistance value until it reaches the first target resistance value, including: The soft shutdown control module controls the first shutdown control circuit to gradually turn on at least one of the third switching transistors that are in a turned-off state, so that the first shutdown control circuit reduces from the initial resistance value to the first target resistance value.

[0010] Optionally, it may also include a second control circuit and a fifth switching transistor; The fifth switch is connected between the voltage output terminal and the reference ground terminal; The input terminal of the second control circuit is connected to the drive signal input terminal, and the output terminal of the second control circuit is connected to the drive terminal of the fifth switch. The second control circuit is used to control the fifth switch to turn off when the first switch is turned on and to turn on when the first switch is turned off.

[0011] Optionally, only one of the first control circuit and the second control circuit may be equipped with a level shifting module.

[0012] Optionally, the first switching transistor is a PMOS transistor; The first shutdown control circuit is located in the pull-up circuit of the first switching transistor.

[0013] Optionally, the first switching transistor is an NMOS transistor; The first shutdown control circuit is located in the pull-down circuit of the first switching transistor.

[0014] Optionally, a clamping circuit may also be provided between the driving terminal of the first switching transistor and the voltage output terminal.

[0015] This invention provides a variable-resistance first turn-off control circuit at the drive terminal of the first switching transistor. A current detection circuit detects the current in the branch containing the first switching transistor. The soft-turn-off control module responds to the turn-off signal at the drive signal input of the first switching transistor and the first signal output by the current detection circuit. The resistance of the first turn-off control circuit decreases from its initial value until it reaches a first target resistance value. Thus, when current flows through the first switching transistor during turn-off, the voltage at the drive terminal changes slowly as the resistance of the first turn-off control circuit decreases. This prevents sudden changes in discharge current from causing induced electromotive force in the parasitic inductance at the power supply terminal, which could lead to voltage spikes. As the resistance of the variable resistor circuit decreases until the first target resistance value is reached, the first switching transistor is completely turned off. Therefore, this invention provides a drive circuit with soft-turn-off functionality. It effectively suppresses voltage spikes generated at the power supply pins when the power switching device is turned off, preventing damage to the power switching device and the drive circuit, and improving system reliability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a driving circuit. Figure 2 This is a schematic diagram of the structure of a first driving circuit provided in an embodiment of the present invention; Figure 3 A waveform diagram of the first switching transistor before and after soft turn-off is provided for an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a second driving circuit provided in an embodiment of the present invention; Figure 5 A method provided by an embodiment of the present invention Figure 5 The waveform diagram of the driving circuit shown; Figure 6 This is a schematic diagram of the structure of the third driving circuit provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the fourth driving circuit provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the fifth driving circuit provided in an embodiment of the present invention. Detailed Implementation

[0018] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0019] It should be noted that, in the description of this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0020] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a schematic diagram of a driving circuit.

[0022] Figure 1This diagram illustrates a typical drive circuit structure, which includes a main switch M1 and an auxiliary switch M2. M1 is connected between the power supply pin VDD and the voltage output terminal OUT, while M2 is connected between the voltage output terminal OUT and the reference ground pin VSS. When both M1 and M2 are NMOS transistors, the drive circuit also includes a pull-up circuit connected to the gate of M1, a pull-down circuit located at the gate of M2, and a level shifting module. The level shifting module splits the same drive signal at the input terminal into two signals with opposite levels, which are then input to the pull-up and pull-down circuits respectively. Additionally, a capacitor C_VDD is typically connected in parallel at the power supply pin. When M1 needs to be turned on, the turn-on signal provided to M1 will turn it on, and M2 will be turned off. When M1 needs to be turned off, the turn-off signal provided to M1 will turn it off, and simultaneously, M2 can quickly pull down the voltage at the voltage output terminal OUT, providing a low-impedance path to ground and rapidly releasing the load charge.

[0023] When M1 is on, the power supply outputs current through the power supply pin VDD and M1. However, the power supply pin typically has a parasitic inductance L1. At the instant M1 is turned off, due to the characteristics of the inductor, the current I_VDD at the power supply pin changes abruptly, resulting in a voltage spike V_spike at VDD. Excessively high voltage spikes can damage the drive circuit. This problem is even more pronounced when the drive circuit has a capacitive load C_load.

[0024] To address the aforementioned issues, this invention provides a driving circuit that offers a soft-turn-off solution for power switching devices. Specifically, a first turn-off control circuit with variable resistance is configured at the driving terminal of the first switching transistor. A current detection circuit detects the current in the branch where the first switching transistor is located. The soft-turn-off control module responds to the turn-off signal at the driving signal input terminal of the first switching transistor and the first signal output by the current detection circuit. It controls the resistance of the first turn-off control circuit to decrease from an initial value until a first target resistance value is reached. Thus, when there is current when the first switching transistor is turned off, the voltage at the driving terminal of the first switching transistor changes slowly as the resistance of the first turn-off control circuit decreases. This prevents sudden changes in discharge current from causing induced electromotive force in the parasitic inductance at the power supply terminal, which would result in a voltage spike at the power supply terminal. As the resistance of the variable resistor circuit decreases until the first target resistance value is reached, the first switching transistor is finally completely turned off. Therefore, the present invention realizes a drive circuit with soft turn-off function, which can effectively suppress the voltage spikes generated at the power supply pin when the power switching device is turned off, avoid damage to the power switching device and even the drive circuit by the voltage spikes, and improve the reliability of the system.

[0025] Figure 2 This is a schematic diagram of the structure of a first driving circuit provided in an embodiment of the present invention.

[0026] like Figure 2 As shown, the driving circuit provided in this embodiment of the invention may include a first switching transistor and a first control circuit; wherein, the first switching transistor is connected between the power supply terminal and the voltage output terminal; the first control circuit includes a current detection circuit, a soft turn-off control module, and a first sub-driving circuit; the first sub-driving circuit is located between the power supply terminal and the reference low-level terminal, and the first sub-driving circuit includes a first turn-on control circuit and a first turn-off control circuit connected in series, the connection point of the first turn-on control circuit and the first turn-off control circuit is connected to the driving terminal of the first switching transistor; the first turn-off control circuit is a variable resistor circuit; the input terminal of the current detection circuit is located in the branch where the first switching transistor is located, the first input terminal of the soft turn-off control module is connected to the output terminal of the current detection circuit, the second input terminal of the soft turn-off control module is connected to the driving signal input terminal of the first switching transistor, and the output terminal of the soft turn-off control module is connected to the resistance adjustment terminal of the first turn-off control circuit; the soft turn-off control module is used to respond to the turn-off signal at the driving signal input terminal and the first signal of the current detection circuit, and control the resistance of the first turn-off control circuit to decrease from the initial resistance value until a first target resistance value is reached.

[0027] like Figure 2 As shown, the driving circuit provided in this embodiment of the invention is located to the left of the dashed line. Its main switching transistor may include a first switching transistor M3. A first sub-driving circuit for the first switching transistor M3 is located between the power supply terminal VDD and the reference low-level terminal. The connection point of the first turn-on control circuit and the first turn-off control circuit in the sub-driving circuit is connected to the driving terminal of the first switching transistor M3.

[0028] Unlike related technologies where the switching transistor's on and off states are directly derived from the drive signal input terminal (Pulse_IN), in this embodiment of the invention, the signal controlling the first switching transistor M3 to turn off is provided by the first turn-off control circuit in the first sub-drive circuit under the control of the soft turn-off control module, thus achieving soft turn-off control.

[0029] In this embodiment of the invention, the first switching transistor may include, but is not limited to, a MOSFET, an IGBT, etc. If the first switching transistor is a MOSFET, it may be an NMOS transistor or a PMOS transistor.

[0030] In this embodiment of the invention, the current in the branch containing the first switching transistor is detected by a current detection circuit, i.e., the magnitude of the current in the first switching transistor is detected. The purpose of soft turn-off is to prolong the turn-off time of the first switching transistor when there is current or a large current in the first switching transistor, thereby avoiding voltage spikes at VDD caused by sudden current changes. The input terminal of the current detection circuit can be set at the driving terminal of the first switching transistor and at least one of the other two pins. When the current detection value is greater than a first preset current value, the current detection circuit outputs a first signal to the soft turn-off control module.

[0031] Simultaneously, the soft-shutdown control module also receives signals from the drive signal input terminal. When it identifies the current as the turn-off signal of the first switching transistor and satisfies the condition that the current detection circuit outputs the first signal, the soft-shutdown control module performs soft-shutdown control on the first turn-off control circuit. Specifically, it controls the resistance value of the first turn-off control circuit to change from large to small, thereby effectively suppressing sudden changes in the conduction voltage of the first switching transistor at the beginning of the turn-off, i.e., suppressing sudden current changes and suppressing the voltage spike V_spike at VDD. Figure 2 As shown.

[0032] In this embodiment of the invention, for the first turn-off control circuit, the initial resistance value can be the maximum resistance value of the first turn-off control circuit, and the first target resistance value can be the minimum resistance value of the first turn-off control circuit. The first turn-off control circuit may include only two states: the initial resistance value and the first target resistance value, or it may include more resistance value states. By controlling the resistance value of the first turn-off control circuit to change from large to small when the first switch is turned off, the turn-off process of the first switch is controlled to go from slow to fast, avoiding voltage spikes at the beginning of turn-off and improving turn-off efficiency in the later stages of turn-off.

[0033] In embodiments of the present invention, such as Figure 2 As shown, the soft shutdown control module may include a short pulse control circuit and a switch control circuit; the first input terminal of the short pulse control circuit is connected to the output terminal of the current detection circuit, the second input terminal of the short pulse control circuit is connected to the drive signal input terminal of the first switch, the output terminal of the short pulse control circuit is connected to the input terminal of the switch control circuit, and the output terminal of the switch control circuit is connected to the resistance adjustment terminal of the first shutdown control circuit.

[0034] The Short Pulse Control circuit is used to respond to the first signal output by the current detection circuit and provide a short pulse (e.g., a signal of about tens of nanoseconds) to the switch control circuit to trigger the switch control circuit to execute the soft shutdown control logic of the first shutdown control circuit.

[0035] In this embodiment of the invention, the soft shutdown control module can also be used to control the resistance value of the first shutdown control circuit to maintain a second target resistance value in response to the shutdown signal at the drive signal input terminal and the second signal of the current detection circuit, wherein the second target resistance value is less than the initial resistance value.

[0036] In other words, when the soft shutdown control module identifies the current signal as the shutdown signal of the first switching transistor, but the current detection circuit outputs the second signal instead of the first signal, it indicates that the current is not a large current shutdown of the first switching transistor. In this case, the soft shutdown logic does not need to be executed. The soft shutdown control module can directly control the first shutdown control circuit to the second target resistance value, thereby improving the shutdown efficiency of the first switching transistor.

[0037] The driving circuit provided in this embodiment of the invention may further include a second control circuit and a fifth switching transistor; the fifth switching transistor is connected between the voltage output terminal and the reference ground terminal; the input terminal of the second control circuit is connected to the driving signal input terminal, and the output terminal of the second control circuit is connected to the driving terminal of the fifth switching transistor; the second control circuit is used to control the fifth switching transistor to turn off when the first switching transistor is turned on and to turn on when the first switching transistor is turned off.

[0038] like Figure 2 As shown, the first switch M3 is the main switch, and the fifth switch M4 is the auxiliary switch. If both the first and fifth switches M3 and M4 are NMOS transistors, then the first control circuit is a pull-up circuit, and the second control circuit is a pull-down circuit. The first control circuit may include a pull-up control circuit, a soft-shutdown control module, a current detection circuit, and a first sub-drive circuit; the second control circuit may include a pull-down control circuit and a second sub-drive circuit. The current flowing through the first switch M3 is the charging current Icharge, and the current flowing through the fifth switch M4 is the discharging current Idischarge.

[0039] In order to control the first and fifth switching transistors based on the same drive signal input terminal, in this embodiment of the invention, only one of the first control circuit and the second control circuit is equipped with a level shifting module.

[0040] Figure 3 The waveform diagrams of a first switching transistor before and after soft turn-off are provided for an embodiment of the present invention.

[0041] If the first switch M3 is a PMOS transistor and the fifth switch M4 is an NMOS transistor, the switching waveforms before using the driving circuit provided in this embodiment of the invention are as follows: Figure 3 As shown in the figure above, the turn-off process of the first switching transistor M3 is a hard turn-off. The waveform diagram using the driving circuit provided in this embodiment of the invention is as follows. Figure 3 As shown in the figure below, the first switch M3 has a slower turn-off rate, achieving soft turn-off.

[0042] In some optional embodiments of the present invention, the first shutdown control circuit includes a plurality of second switching transistors connected in parallel between the driving terminal of the first switching transistor and the second conductive terminal of the first switching transistor.

[0043] The soft shutdown control module controls the resistance of the first shutdown control circuit to decrease from the initial resistance value until the first target resistance value is reached. This includes: the soft shutdown control module controls the first shutdown control circuit to gradually turn off at least one second switch that is in the conducting state from the state where there are multiple conducting second switches, so that the variable resistor circuit decreases from the initial resistance value to the first target resistance value.

[0044] In this embodiment of the invention, multiple parallel second switching transistors can be used to make the resistance of the first shutdown control circuit variable. By continuously turning off the second switching transistors, the resistance of the first shutdown control circuit changes from large to small.

[0045] In this embodiment of the invention, if the first switching transistor is a PMOS transistor, then the first turn-off control circuit is located in the pull-up circuit of the first switching transistor. That is, when the first switching transistor is a PMOS transistor, the first turn-off control circuit of the first switching transistor is a pull-up circuit for the first switching transistor. At this time, the first turn-on control circuit of the first switching transistor is a pull-down circuit for the first switching transistor.

[0046] Figure 4 This is a schematic diagram of the structure of a second driving circuit provided in an embodiment of the present invention.

[0047] like Figure 4 As shown, if the first switching transistor is a PMOS transistor M31, then the second switching transistors may include M61, M62...M6n, and these second switching transistors are connected in parallel between the gate and the source of the PMOS transistor M31.

[0048] The switch control circuit can adopt a sequential step-off logic control circuit, which outputs turn-off signals off(1), off(3), ... off(n) in sequence to turn off M61, M62 ... M6n in turn.

[0049] like Figure 4 As shown, in the first turn-on control circuit (pull-down circuit) of PMOS transistor M31, NMOS transistor M51 can be set, and NMOS transistor M51 is connected in parallel between the gate of PMOS transistor M31 and the reference ground level VSS_HS.

[0050] Figure 5 A method provided by an embodiment of the present invention Figure 5 The waveform diagram of the driving circuit is shown.

[0051] based on Figure 4The driving circuit shown uses a current detection circuit to detect whether there is current in the first switching transistor M31 via VDD, M31_gate, and OUT voltages. If there is current, a logic signal is output to the short pulse control module, and a signal of approximately tens of nanoseconds is generated at the falling edge of the driving signal input, i.e., at the turn-off signal of M31, and output to the switching control circuit. Within this time range of approximately tens of nanoseconds, the switching control circuit will sequentially turn off M61, M62...M6n, thereby realizing the soft turn-off function of M31. Its waveform is shown below. Figure 5 As shown, each time a second switch is turned off, the turn-off time of M31 is delayed by a delay time. The turn-off time of n second switches is n*delay time, thus realizing the soft turn-off of M31.

[0052] In this embodiment of the invention, if the first switching transistor is an NMOS transistor, the first turn-off control circuit is located in the pull-down circuit of the first switching transistor. That is, when the first switching transistor is an NMOS transistor, the first turn-off control circuit of the first switching transistor is a pull-down circuit for the first switching transistor. At this time, the first turn-on control circuit of the first switching transistor is a pull-up circuit for the first switching transistor.

[0053] Figure 6 This is a schematic diagram of the third type of driving circuit provided in an embodiment of the present invention.

[0054] like Figure 6 As shown, if the first switching transistor is an NMOS transistor M32, then the second switching transistors may include M71, M72...M7n. These second switching transistors are connected in parallel between the gate of the NMOS transistor M32 and the reference level terminal. The reference level terminal can be ground or other reference low level terminals.

[0055] The switch control circuit can use a sequential step-off logic control circuit, which outputs turn-off signals off(1), off(3), ... off(n) in sequence to turn off M71, M72 ... M7n in turn.

[0056] like Figure 6 As shown, in the first conduction control circuit (pull-up circuit) of NMOS transistor M32, PMOS transistor M52 can be set, and PMOS transistor M52 is connected in parallel between the gate of NMOS transistor M32 and the power supply terminal VDD.

[0057] like Figure 6 As shown, the driving circuit provided in this embodiment of the invention may further include a clamping circuit disposed between the driving terminal and the voltage output terminal of the first switching transistor. When the clamping circuit is present, the reference level terminal can be a ground terminal; otherwise, it is a reference low level terminal.

[0058] In some alternative embodiments of the present invention, the first shutdown control circuit includes a first branch and a second branch connected in series. The first branch includes a third switch and a first resistor connected in parallel, and the second branch includes a fourth switch. The driving terminal of the third switch is connected to the soft shutdown control module, and the driving terminal of the fourth switch is connected to the driving signal input terminal.

[0059] The soft shutdown control module controls the resistance of the first shutdown control circuit to decrease from the initial resistance value until the first target resistance value is reached. This includes: the soft shutdown control module controls the first shutdown control circuit to gradually turn on at least one third switch that is in the off state from the state where at least one third switch is off, so that the resistance of the first shutdown control circuit decreases from the initial resistance value to the first target resistance value.

[0060] In this embodiment of the invention, the first switching transistor is gradually turned off by connecting the first branch and the second branch in series. Specifically, the fourth switching transistor in the first turn-off control circuit responds to the turn-off signal input at the drive signal input terminal and is directly turned on to convey the turn-off action to the first switching transistor. Under the control of the soft turn-off control module, the third switching transistor is turned off later than the fourth switching transistor. Thus, when the turn-off signal is received, the first resistor in the first turn-off control circuit is connected to the circuit to avoid voltage spikes. Subsequently, the first resistor is short-circuited by the conduction of the third switching transistor, which enables the rapid turn-off of the first switching transistor in the later stage of the turn-off.

[0061] In this embodiment of the invention, the number of third switching transistors can be one or more. If there is only one third switching transistor, the logic of the switch control circuit in the soft shutdown control module is to control the third switching transistor to turn on with a delay compared to the fourth switching transistor from its off state. If there are multiple third switching transistors, the logic of the switch control circuit in the soft shutdown control module is to sequentially control each third switching transistor to turn on from its off state, thereby achieving the effect of the resistance value of the entire first shutdown control circuit changing from large to small.

[0062] In this embodiment of the invention, if the first switching transistor is a PMOS transistor, then the first turn-off control circuit is located in the pull-up circuit of the first switching transistor. That is, when the first switching transistor is a PMOS transistor, the first turn-off control circuit of the first switching transistor is a pull-up circuit for the first switching transistor. At this time, the first turn-on control circuit of the first switching transistor is a pull-down circuit for the first switching transistor.

[0063] Figure 7 This is a schematic diagram of the fourth driving circuit provided in an embodiment of the present invention.

[0064] like Figure 7As shown, if the first switching transistor is a PMOS transistor M33, then the first turn-off control circuit is connected in parallel between the gate and source of the PMOS transistor M33. The first turn-off control circuit may include a third switching transistor M81, a first resistor R1, and a fourth switching transistor M82. Both the third switching transistor M81 and the fourth switching transistor M82 are PMOS transistors, and the switching control circuit controls the third switching transistor M81 to turn on with a delay compared to the fourth switching transistor M82.

[0065] like Figure 7 As shown, in the first conduction control circuit (pull-down circuit) of PMOS transistor M33, NMOS transistor M53 can be set, and NMOS transistor M53 is connected in parallel between the gate of PMOS transistor M33 and the reference ground level VSS_HS.

[0066] In this embodiment of the invention, if the first switching transistor is an NMOS transistor, then the first turn-off control circuit is located in the pull-down circuit of the first switching transistor. In this case, the first turn-on control circuit of the first switching transistor is a pull-up circuit for the first switching transistor.

[0067] Figure 8 This is a schematic diagram of the fifth driving circuit provided in an embodiment of the present invention.

[0068] like Figure 8 As shown, if the first switching transistor is an NMOS transistor M34, then the first turn-off control circuit is connected in parallel between the gate of the NMOS transistor M34 and the reference level terminal. The reference level terminal can be ground or other reference low level terminals.

[0069] The first turn-off control circuit may include a third switch M91, a first resistor R1, and a fourth switch M92. Both the third switch M91 and the fourth switch M92 are NMOS transistors, and the switch control circuit controls the third switch M91 to turn on with a delay compared to the fourth switch M92.

[0070] like Figure 8 As shown, in the first conduction control circuit (pull-up circuit) of NMOS transistor M34, PMOS transistor M54 can be set, and PMOS transistor M54 is connected in parallel between the gate of NMOS transistor M34 and the power supply terminal VDD.

[0071] like Figure 8 As shown, the driving circuit provided in this embodiment of the invention may further include a clamping circuit disposed between the driving terminal and the voltage output terminal of the first switching transistor. When the clamping circuit is present, the reference level terminal can be a ground terminal; otherwise, it is a reference low level terminal.

[0072] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0073] The driving circuit provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only intended to help understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of this invention.

Claims

1. A drive circuit characterized by comprising: Includes a first switching transistor and a first control circuit; The first switching transistor is connected between the power supply terminal and the voltage output terminal; The first control circuit includes a current detection circuit, a soft shutdown control module, and a first sub-drive circuit; The first sub-driving circuit is located between the power supply terminal and the reference low-level terminal. The first sub-driving circuit includes a first turn-on control circuit and a first turn-off control circuit connected in series. The connection point of the first turn-on control circuit and the first turn-off control circuit is connected to the driving terminal of the first switching transistor. The first turn-off control circuit is a variable resistor circuit. The input terminal of the current detection circuit is located in the branch where the first switching transistor is located. The first input terminal of the soft shutdown control module is connected to the output terminal of the current detection circuit. The second input terminal of the soft shutdown control module is connected to the drive signal input terminal of the first switching transistor. The output terminal of the soft shutdown control module is connected to the resistance adjustment terminal of the first shutdown control circuit. The soft shutdown control module is used to respond to the shutdown signal at the drive signal input terminal and the first signal of the current detection circuit to control the resistance value of the first shutdown control circuit to decrease from the initial resistance value until the first target resistance value is reached.

2. The drive circuit according to claim 1, characterized in that, The soft shutdown control module is also used to control the resistance value of the first shutdown control circuit to maintain a second target resistance value in response to the shutdown signal at the drive signal input terminal and the second signal of the current detection circuit, wherein the second target resistance value is less than the initial resistance value.

3. The drive circuit according to claim 1, characterized by The soft shutdown control module includes a short pulse control circuit and a switch control circuit; The first input terminal of the short pulse control circuit is connected to the output terminal of the current detection circuit, the second input terminal of the short pulse control circuit is connected to the drive signal input terminal of the first switching transistor, the output terminal of the short pulse control circuit is connected to the input terminal of the switch control circuit, and the output terminal of the switch control circuit is connected to the resistance adjustment terminal of the first turn-off control circuit.

4. The drive circuit according to claim 1, characterized by The first shutdown control circuit includes a plurality of second switching transistors connected in parallel between the driving terminal of the first switching transistor and the second conductive terminal of the first switching transistor; The soft shutdown control module controls the resistance value of the first shutdown control circuit to decrease from its initial resistance value until it reaches the first target resistance value, including: The soft shutdown control module controls the first shutdown control circuit to gradually shut down at least one of the second switching transistors that are in a conducting state, so that the variable resistor circuit reduces from the initial resistance value to the first target resistance value.

5. The drive circuit according to claim 1, characterized by The first shutdown control circuit includes a first branch and a second branch connected in series. The first branch includes a third switch and a first resistor connected in parallel. The second branch includes a fourth switch. The driving terminal of the third switch is connected to the soft shutdown control module, and the driving terminal of the fourth switch is connected to the driving signal input terminal. The soft shutdown control module controls the resistance value of the first shutdown control circuit to decrease from its initial resistance value until it reaches the first target resistance value, including: The soft shutdown control module controls the first shutdown control circuit to gradually turn on at least one of the third switching transistors that are in a turned-off state, so that the first shutdown control circuit reduces from the initial resistance value to the first target resistance value.

6. The driving circuit according to claim 1, characterized in that, It also includes a second control circuit and a fifth switching transistor; The fifth switch is connected between the voltage output terminal and the reference ground terminal; The input terminal of the second control circuit is connected to the drive signal input terminal, and the output terminal of the second control circuit is connected to the drive terminal of the fifth switch. The second control circuit is used to control the fifth switch to turn off when the first switch is turned on and to turn on when the first switch is turned off.

7. The driving circuit according to claim 6, characterized in that, Only one of the first control circuit and the second control circuit has a level shifting module.

8. The driving circuit according to any one of claims 1 to 7, characterized in that, The first switching transistor is a PMOS transistor; The first shutdown control circuit is located in the pull-up circuit of the first switching transistor.

9. The driving circuit according to any one of claims 1 to 7, characterized in that, The first switching transistor is an NMOS transistor; The first shutdown control circuit is located in the pull-down circuit of the first switching transistor.

10. The driving circuit according to claim 9, characterized in that, It also includes a clamping circuit located between the driving terminal of the first switching transistor and the voltage output terminal.

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