Driving control circuit of power tube

Abstract

The utility model discloses a driving control circuit of a power tube, and belongs to the technical field of switching power supplies. According to the driving control circuit of the power tube, the input end of a driving voltage control module is configured to receive feedback voltage of a circuit where the power tube is located, and the output end of the driving voltage control module is configured to output first driving voltage based on the feedback voltage of a first multiple; the input end of the driving current control module is configured to receive a feedback voltage and a valley signal corresponding to a power tube, and the output end of the driving current control module is configured to output a first control signal; the input end of the driving module is connected with the output end of the driving voltage control module and the output end of the driving current control module, and the output end of the driving module is connected with the grid electrode of the power tube. According to the driving control circuit of the power tube, the conduction loss of the power tube is reduced, the current driving state can be accurately distinguished, and the driving current intensity influence caused by inaccurate state characterization can be avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of switching power supply, and particularly relates to a driving control circuit of a power tube. BACKGROUND

[0002] Gallium nitride (GaN) power tube driving has more advantages than traditional MOS power tube driving, and is often applied to switching power supply. However, the maximum gate voltage of the gallium nitride power tube is low, and the conduction threshold is about 1.2V-2V. A fixed voltage is added to the gate end of the power tube to drive the gallium nitride power tube. As the power tube is turned on, the source end voltage increases, resulting in a decrease in the gate-source voltage, which may increase the conduction loss and cause insufficient opening. In the related art, a circuit structure is provided, in which a voltage obtained by adding a real-time sampled source end voltage and a fixed voltage is used to drive a driving module, and the driving is segmented according to the size of a system feedback signal representing an output voltage. This circuit design is complex, the sampling accuracy is low, and the sampling voltage error is large. The circuit is easily affected by parasitic inductance and parasitic capacitance. The system feedback signal is easily affected by the load and the input voltage, and the strong current driving and weak current driving cannot be accurately distinguished, which may cause large power tube voltage spikes and secondary stress, or large switching loss and conduction loss, resulting in a decrease in the efficiency of the system. CONTENT OF THE UTILITY MODEL

[0003] The application aims to at least solve one of the technical problems in the prior art. To this end, the application provides a driving control circuit of a power tube, which solves the problem of inaccurate source end voltage sampling and complex circuit design, and reduces the conduction loss of the power tube, so that the influence of the driving current strength caused by inaccurate state representation can be effectively avoided.

[0004] In a first aspect, the application provides a driving control circuit of a power tube, which includes:

[0005] A driving voltage control module, an input end of the driving voltage control module being configured to receive a feedback voltage of a circuit in which the power tube is located, and an output end of the driving voltage control module being configured to output a first driving voltage based on the feedback voltage multiplied by a first factor;

[0006] A driving current control module, an input end of the driving current control module being configured to receive the feedback voltage and a valley signal corresponding to the power tube, and an output end of the driving current control module being configured to output a first control signal; the valley signal is used to represent that the waveform oscillation of the source end voltage of the power tube reaches the lowest point;

[0007] A driving module, input ends of the driving module being connected with the output end of the driving voltage control module and the output end of the driving current control module respectively, and an output end of the driving module being connected with a gate of the power tube.

[0008] The driving module is configured to convert the first driving voltage into a target driving voltage and convert the first control signal into a driving current to drive the power tube to work.

[0009] The driving control circuit of the power tube provided by the embodiment of the present application solves the problem of inaccurate sampling of the source voltage and complex circuit design by configuring the driving voltage control module to sample the feedback voltage and obtain the target driving voltage according to the feedback voltage of the first multiple, and reduces the conduction loss of the power tube; the driving current control module is configured to distinguish different current driving states according to the valley signal and the feedback voltage, so that appropriate driving current can be output according to the current driving state, and the influence of the driving current strength caused by inaccurate state representation can be effectively avoided.

[0010] The driving control circuit of the power tube of one embodiment of the present application, the driving voltage control module comprises:

[0011] The proportional circuit is configured to receive the feedback voltage at the input end, and output the feedback voltage of the first multiple at the output end;

[0012] The low-dropout linear voltage regulator is configured to output a fixed voltage at the output end;

[0013] The voltage addition module is connected to the output end of the proportional circuit and the output end of the low-dropout linear voltage regulator at the input end, and is configured to output the first driving voltage.

[0014] The driving control circuit of the power tube of one embodiment of the present application, the proportional circuit comprises:

[0015] The first resistor, the second resistor and the third resistor are connected in series, one end of the first resistor is connected to the first end, the other end of the first resistor is configured to receive the feedback voltage, and the first end is configured to receive a voltage source signal; one end of the second resistor close to the first resistor is configured to receive the feedback voltage; one end of the third resistor away from the second resistor is grounded;

[0016] The voltage of the third resistor is the feedback voltage of the first multiple.

[0017] The driving control circuit of the power tube of one embodiment of the present application, the proportional circuit comprises:

[0018] The fourth resistor is grounded at one end, and the other end of the fourth resistor is configured to receive the feedback voltage;

[0019] a first transistor, a drain of the first transistor being connected with another end of the fourth resistor;

[0020] a second transistor, a current of the second transistor being a second multiple of a current of the first transistor;

[0021] a fifth resistor and a sixth resistor connected in series, one end of the fifth resistor being connected with a drain of the second transistor; the sixth resistor being grounded away from one end of the fifth resistor, and one end of the sixth resistor being connected with one end of the fourth resistor;

[0022] a voltage of the sixth resistor being a feedback voltage of the first multiple.

[0023] The driving control circuit of the power tube in one embodiment of the present application comprises:

[0024] a valley bottom counting module, an input end of the valley bottom counting module being configured to receive the valley bottom signal, and an output end of the valley bottom counting module being configured to output a valley bottom number of the valley bottom signal in a current switching period;

[0025] a voltage comparison module, one input end of the voltage comparison module being configured to receive the feedback voltage, another input end of the voltage comparison module being configured to receive a target voltage threshold, and an output end of the voltage comparison module being configured to output a first comparison signal;

[0026] a control signal generation module, input ends of the control signal generation module being connected with the output end of the valley bottom counting module and the output end of the voltage comparison module respectively, and an output end of the control signal generation module being configured to output the first control signal.

[0027] The driving control circuit of the power tube in one embodiment of the present application comprises:

[0028] a counter, an input end of the counter being configured to receive the valley bottom signal;

[0029] a latch, input ends of the latch being connected with an output end of the counter;

[0030] a decoding circuit, input ends of the decoding circuit being connected with the output end of the counter and an output end of the latch respectively, and an output end of the decoding circuit being configured to output a valley bottom number of the valley bottom signal in the current switching period.

[0031] The driving control circuit of the power tube in one embodiment of the present application comprises:

[0032] a first inverter, an input end of the first inverter being connected with an output end of the voltage comparison module, and an output end of the first inverter being configured to output the first sub-control signal;

[0033] a NOR circuit, one input end of the NOR circuit being connected with an output end of the first inverter, another input end of the NOR circuit being connected with an output end of the valley bottom counting module, and an output end of the NOR circuit being configured to output the second sub-control signal;

[0034] a NAND circuit, one input end of the NAND circuit being connected with an output end of the voltage comparison module, and another input end of the NAND circuit being connected with an output end of the valley bottom counting module;

[0035] a second inverter, an input end of the second inverter being connected with an output end of the NAND circuit, and an output end of the second inverter being configured to output the third sub-control signal.

[0036] The power tube driving control circuit of one embodiment of the present application, the first control signal includes a first sub-control signal, a second sub-control signal and a third sub-control signal; the control signal generation module includes:

[0037] a third inverter, an input end of the third inverter being connected with an output end of the voltage comparison module, and an output end of the third inverter being configured to output the first sub-control signal;

[0038] a first flip-flop, a first input end of the first flip-flop being connected with an output end of the voltage comparison module, a second input end of the first flip-flop being connected with an output end of the valley bottom counting module, and an output end of the first flip-flop being configured to output the second sub-control signal;

[0039] a fourth inverter, an input end of the fourth inverter being connected with an output end of the valley bottom counting module;

[0040] a second flip-flop, a third input end of the second flip-flop being connected with an output end of the voltage comparison module, a fourth input end of the second flip-flop being connected with an output end of the fourth inverter, and an output end of the second flip-flop being configured to output the third sub-control signal.

[0041] The power tube driving control circuit of one embodiment of the present application, the driving module includes:

[0042] a first driving circuit;

[0043] a second driving circuit, the second driving circuit being connected in parallel with the first driving circuit;

[0044] A third drive circuit is connected in parallel with the first drive circuit and the second drive circuit respectively.

[0045] The first drive circuit, the second drive circuit and the third drive circuit are configured to be selectively turned on based on the first control signal.

[0046] The drive control circuit of the power tube in an embodiment of the present application includes:

[0047] An AND circuit has one input configured to receive the first control signal and another input configured to receive a turn-on control signal.

[0048] A target switch has one end connected to the output of the AND circuit, and the voltage at the one end of the target switch is the first drive voltage.

[0049] A drive tube has a gate connected to the other end of the target switch and a drain connected to the gate of the power tube.

[0050] The one or more technical solutions described above in the embodiments of the present application have at least one of the following technical effects:

[0051] By configuring the drive voltage control module to sample the feedback voltage and obtain the target drive voltage according to the feedback voltage of the first multiple, the problem of inaccurate source voltage sampling and complex circuit design is solved, and the turn-on loss of the power tube is reduced; by configuring the drive current control module to distinguish different current drive states according to the valley signal and the feedback voltage, the appropriate drive current can be output according to the current drive state, and the influence of the strength of the drive current caused by inaccurate state representation can be effectively avoided.

[0052] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter in the description of embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0053] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings in which:

[0054] Figure 1 is a structural schematic diagram of a drive control circuit in the related art;

[0055] Figure 2 is a control logic schematic diagram of a drive control circuit in the related art;

[0056] Figure 3 is a waveform schematic diagram of a drive control circuit in the related art;

[0057] Figure 4 is a structural schematic diagram of a switching power supply system provided by an embodiment of the present application;

[0058] Figure 5 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0059] Figure 6 is a structural schematic diagram of a switching power supply system provided by an embodiment of the present application;

[0060] Figure 7 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0061] Figure 8 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0062] Figure 9 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0063] Figure 10 is a waveform schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0064] Figure 11 is a control logic schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0065] Figure 12 is a waveform schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0066] Figure 13 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0067] Figure 14 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0068] Figure 15 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application;

[0069] Figure 16 is a structural schematic diagram of a driving control circuit of a power tube provided by an embodiment of the present application.

[0070] Reference signs:

[0071] Driving voltage control module 110; driving current control module 120; driving module 130; proportional circuit 140;

[0072] Voltage addition module 150; valley bottom counting module 160; voltage comparison module 170; control signal generation module 180;

[0073] Counter 190; latch 200; decoding circuit 210; first flip-flop 220; second flip-flop 230;

[0074] First AND circuit 240; second AND circuit 250; third AND circuit 260; power tube Q1; first resistor R1;

[0075] Second resistor R2; third resistor R3; fourth resistor R4; fifth resistor R5; sixth resistor R6;

[0076] Low-dropout linear regulator LDO; first transistor M1; second transistor M2; first inverter INV1;

[0077] Second inverter INV2; third inverter INV3; fourth inverter INV4; NOR circuit NOR1;

[0078] NAND circuit NAND1; first switch S1; second switch S2; third switch S3; first drive tube N1;

[0079] Second drive tube N2; third drive tube N3. DETAILED DESCRIPTION

[0080] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0081] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be exchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally a category and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in an "or" relationship.

[0082] 1. In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0083] 2. In the description of the present application, "a plurality of" means two or more.

[0084] The embodiment of the present application provides a driving control circuit of a power tube.

[0085] It should be noted that the power tube Q1 can be arranged outside the driving control circuit of the power tube, or the power tube Q1 and the driving control circuit of the power tube can be packaged together, which can be selected based on user demand, and the present application is not limited.

[0086] As shown in FIG. 1, in some embodiments, the driving control circuit of the power tube includes a driving voltage control module 110, a driving current control module 120 and a driving module 130. Figure 5 In this embodiment, the input end of the driving voltage control module 110 is configured to receive a feedback voltage of the circuit in which the power tube Q1 is located, as shown in FIG. 1.

[0087] Figure 4 The input end of the driving voltage control module 110 can be connected to the FB pin.

[0088] The power tube Q1 can be a gallium nitride (GaN) power tube, and the power tube Q1 can be arranged in a switching power supply system.

[0089] The feedback voltage is used to represent the size of the output voltage of the switching power supply system, and the larger the output voltage, the larger the feedback voltage, and the smaller the output voltage, the smaller the feedback voltage.

[0090] The output end of the driving voltage control module 110 is configured to output a first driving voltage based on the feedback voltage of the first multiple.

[0091] The size of the first multiple can be customized by the user, for example, the first multiple can be set to any value in 1 / 6-1 / 4, and the present application is not limited.

[0092] The first driving voltage can be determined based on the feedback voltage of the first multiple, for example, the first driving voltage can be the sum of the feedback voltage of the first multiple and a fixed voltage.

[0093] The input end of the driving current control module 120 is configured to receive the feedback voltage and the corresponding valley signal of the power tube Q1.​

[0094] The valley signal is used to represent the waveform oscillation of the source voltage of the power tube Q1 to the lowest point. After the demagnetization of the power tube Q1 is completed, the source of the power tube Q1 will oscillate, as shown in the waveform of V Figure 12 DS The waveform of the ZCD pin and the waveform of V DS The phase of the waveform is consistent, and the amplitude is different. When the waveform of the source of the power tube Q1 oscillates to the lowest point, a pulse signal Valley, i.e. the valley signal, can be generated.

[0095] As shown in Figure 4 The input end of the drive current control module 120 can be connected to the ZCD pin. When the switching power supply system is working normally, the ZCD pin can sample the valley signal.

[0096] The output end of the drive current control module 120 is configured to output a first control signal.

[0097] As shown in Figure 5 The first control signal can include a plurality of sub-control signals. The drive current control module 120 can output any sub-control signal as high level and other sub-control signals as low level according to at least one of the feedback voltage and the valley signal.

[0098] The first control signal can be used to determine the working mode of the switching power supply system. The working mode can include a weak current drive mode, a medium current drive mode, or a strong current drive mode, or can also include other types of working modes, which are not limited by the present application.

[0099] The input end of the drive module 130 is connected to the output end of the drive voltage control module 110 and the output end of the drive current control module 120, respectively. The output end of the drive module 130 is connected to the gate of the power tube Q1.

[0100] As shown in Figure 4 The switching power supply system structure diagram of the power tube Q1 outside the drive control circuit of the power tube is exemplified, as shown in Figure 4 The output end of the drive module 130 can be connected to the DRV pin, and the DRV pin is connected to the gate of the power tube Q1.

[0101] As shown in Figure 6 The switching power supply system structure diagram of the power tube Q1 and the drive control circuit of the power tube packaged together is exemplified, as shown in Figure 7 The output end of the drive module 130 can be connected to the gate of the power tube Q1. The source of the power tube Q1 can be connected to the CS pin, and the drain of the power tube Q1 can be connected to the Drain pin.

[0102] ​The driving module 130 is configured to convert the first driving voltage into a target driving voltage and convert the first control signal into a driving current, the target driving voltage and the driving current being used to drive the power tube Q1 to work.

[0103] After the first driving voltage is input into the driving module 130, the first driving voltage will lose about a threshold voltage of a transistor through the driving module 130, and finally the driving voltage input into the power tube Q1 is the difference between the first driving voltage and the threshold voltage, that is, the target driving voltage.

[0104] The driving module 130 can output a driving current matched with the first control signal according to the first control signal, and input the driving current into the power tube Q1.

[0105] The inventors found in the development process that the related art has the following problems. Figure 1 As shown in the driving control circuit, a fixed voltage VLDO is output by an LDO, a voltage VDRV_IN obtained by adding a source voltage VCS sampled in real time and the fixed voltage VLDO output by the LDO is input into a driving circuit, and a threshold voltage Vth of a transistor is usually lost through the driving circuit, that is, a DRV voltage is equal to VDRV_IN-Vth, and the DRV voltage is used to drive a gallium nitride (GaN) power tube Q1, and a working waveform of the gallium nitride (GaN) power tube Q1 is as shown in Figure 3 As shown in the driving control circuit, a fixed voltage VLDO is output by an LDO, a voltage VDRV_IN obtained by adding a source voltage VCS sampled in real time and the fixed voltage VLDO output by the LDO is input into a driving circuit, and a threshold voltage Vth of a transistor is usually lost through the driving circuit, that is, a DRV voltage is equal to VDRV_IN-Vth, and the DRV voltage is used to drive a gallium nitride (GaN) power tube Q1, and a working waveform of the gallium nitride (GaN) power tube Q1 is as shown in

[0106] In the case that the driving current of the power tube Q1 is too large, the opening speed is too fast, which can cause a large power tube Q1 voltage spike and secondary stress; in the case that the driving current is too small, the opening speed of the power switch tube becomes slow, which can cause a large switching loss and conduction loss, resulting in a reduction in system efficiency, and in the related art, the driving is performed in sections through the size of a feedback signal FB, as shown in Figure 2As shown, when the voltage of the FB is less than the reference voltage VREF1, weak current driving is adopted, and when the voltage of the FB is greater than the reference voltage VREF1, strong current driving is adopted. In this scheme, the feedback signal FB is not only affected by the load but also affected by the input voltage. For example, in the case of high input voltage and light load, the FB voltage may be greater than the reference voltage VREF1, and the scheme will adopt strong current driving, but in this case, weak current driving should be adopted, thereby causing a large power tube Q1 voltage spike and secondary stress. The scheme cannot accurately distinguish between strong current driving and weak current driving.

[0107] In the present application, the first multiple feedback voltage is obtained, and the first driving voltage is output according to the first multiple feedback voltage. The first multiple feedback voltage can represent the maximum voltage at the source end of the power tube Q1 when the power tube Q1 is turned on. With the opening of the power tube Q1, the gate-source voltage will increase and will not exceed the safe working range. The feedback voltage will not produce glitches in the power tube Q1 opening stage, avoiding real-time sampling of the source end voltage, solving the sampling error problem caused by oscillation when the power tube Q1 is turned on, and the circuit design is simple and easy to implement. In addition, the on-state impedance decreases with the increase of the gate-source voltage, and the on-state loss also decreases.

[0108] The valley bottom number of the ZCD pin and the FB voltage are sampled to output a first control signal for representing the strength of the current driving. The strong current driving, the medium current driving and the weak current driving state can be distinguished by the valley bottom signal and the feedback voltage. Then, corresponding current driving is adopted for different states. The problem of excessive driving current of the power tube Q1, too fast opening speed of the power tube Q1, resulting in a large power tube Q1 voltage spike, too small driving current, slow opening speed of the power switch tube, resulting in large switching loss and on-state loss, and low system efficiency is solved.

[0109] According to the driving control circuit of the power tube provided in the embodiments of the present application, the driving voltage control module 110 is configured to sample the feedback voltage and obtain the target driving voltage according to the first multiple feedback voltage, thereby solving the problem of inaccurate sampling of the source end voltage and complex circuit design, and reducing the on-state loss of the power tube Q1. The driving current control module 120 is configured to distinguish different current driving states according to the valley bottom signal and the feedback voltage, so that appropriate driving current can be output according to the current driving state, and the influence of the driving current strength caused by inaccurate state representation can be effectively avoided.

[0110] In some embodiments, the driving voltage control module 110 can include a proportional circuit 140, a low dropout linear regulator LDO and a voltage addition module 150.

[0111] In this embodiment, the input end of the proportional circuit 140 is configured to receive the feedback voltage, and the output end of the proportional circuit 140 is configured to output the feedback voltage multiplied by the first multiple.

[0112] The output end of the low dropout voltage regulator LDO is configured to output a fixed voltage. The low dropout voltage regulator LDO can convert a higher voltage into a lower stable voltage while maintaining a lower voltage drop. The low dropout voltage regulator LDO can control the output voltage through a feedback loop to keep it constant. When the load current changes, the low dropout voltage regulator LDO can automatically adjust the control circuit to ensure that the output voltage always remains at the set value.

[0113] The input end of the voltage addition module 150 is connected to the output end of the proportional circuit 140 and the output end of the low dropout voltage regulator LDO, respectively. The voltage addition module 150 is configured to output the first drive voltage.

[0114] During the driving of the power tube Q1, the feedback voltage can be sampled. After passing through the proportional circuit 140, K*VFB (K is the first multiple) can be obtained. In the flyback switching power supply system, according to the current loop control, the value of K*VFB is equal to the voltage of the peak current of the power tube Q1 flowing through Rcs, that is, K*VFB is equal to the peak value of the source voltage VCS of the power tube Q1. The value VDRV_IN obtained by adding K*VFB and the fixed voltage VLDO output by the LDO is input to the driving module 130.

[0115] The proportional circuit 140 can include various circuit structures, which can be selected based on user needs, and the present application does not make any limitation.

[0116] As shown in FIG. 1, Figure 8 In some embodiments, the proportional circuit 140 can include a first resistor R1, a second resistor R2, and a third resistor R3 connected in series,

[0117] In this embodiment, one end of the first resistor R1 is connected to the first end, and the first end is configured to receive the voltage source signal VDD.

[0118] The other end of the first resistor R1 is configured to receive the feedback voltage. For example, the other end of the first resistor R1 can be connected to the FB pin.

[0119] The end of the second resistor R2 close to the first resistor R1 is configured to receive the feedback voltage, that is, the end of the second resistor R2 close to the first resistor R1 is connected to the FB pin.

[0120] The end of the second resistor R2 furthest from the first resistor R1 is connected to the third resistor R3, and the output voltage signal is also connected.

[0121] The end of the third resistor R3 furthest from the second resistor R2 is grounded, and the voltage across the third resistor R3 is a multiple of the feedback voltage.

[0122] The feedback voltage of the first multiple output by the proportional circuit 140 can be sent to one end of the voltage adder module 150. The voltage adder module 150 can obtain the first drive voltage VDRV_IN by adding the feedback voltage of the first multiple and the fixed voltage VLDO generated by the low dropout linear regulator LDO.

[0123] The feedback voltage for the first multiple is:

[0124]

[0125] Right now, A suitable value for K can be obtained by setting the resistance values ​​of the second resistor R2 and the third resistor R3.

[0126] like Figure 9 As shown, in some embodiments, the proportional circuit 140 may include: a fourth resistor R4, a first transistor M1, a second transistor M2, and a fifth resistor R5 and a sixth resistor R6 connected in series.

[0127] In this embodiment, one end of the fourth resistor R4 is grounded, and the other end of the fourth resistor R4 is configured to receive feedback voltage.

[0128] The drain of the first transistor M1 is connected to the other end of the fourth resistor R4.

[0129] The current of the second transistor M2 is a second multiple of the current of the first transistor M1. That is, the second transistor M2 can mirror the current on the first transistor M1 according to a certain ratio K1 (i.e., the second multiple, usually an integer multiple).

[0130] One end of the fifth resistor R5 is connected to the drain of the second transistor M2, and the other end of the fifth resistor R5 is connected to the sixth resistor R6 and the output voltage signal.

[0131] The end of the sixth resistor R6 furthest from the fifth resistor R5 is grounded, and the end of the sixth resistor R6 furthest from the fifth resistor R5 is connected to one end of the fourth resistor R4.

[0132] The voltage across the sixth resistor R6 is a multiple of the feedback voltage.

[0133] The voltage signal (the first multiple of the feedback voltage) output by the proportional circuit 140 is input into one end of the voltage addition module 150 and can be added to the fixed voltage VLDO generated by the low dropout linear voltage regulator LDO to obtain the first driving voltage VDRV_IN.

[0134] wherein the K1 is based on Figure 9 It can be known that:

[0135] I1 = VFB / R4

[0136] I2 = K1*I1

[0137]

[0138] The K1 (the second multiple) is a mirror ratio of the current mirror, which can be adjusted by adjusting the width-length ratio of the first transistor M1 and the second transistor M2.

[0139] From the above formula, it can be known that: By setting a reasonable proportional coefficient K1 or the resistance values of the fourth resistor R4 and the sixth resistor R6, a suitable K can be obtained.

[0140] In the actual execution process, the first driving voltage VDRV_IN will lose about a threshold voltage Vth of a transistor when passing through the driving module 130, and the target driving voltage DRV input to the driving tube is equal to VDRV_IN-Vth. The working waveform of the target driving voltage is as shown in FIG. 6. Figure 10 The value of the target driving voltage DRV is K*VFB+VLDO-Vth, and the gate-source voltage VGS of the power tube Q1 is K*VFB+VLDO-VCS-Vth. With the opening of the power tube Q1, the source voltage VCS gradually rises, and the gate-source voltage VGS gradually decreases, and finally is VLDO-Vth.

[0141] Compared with the traditional gallium nitride power tube Q1, the gate-source voltage VGS of the power tube Q1 is increased, and the increased value dynamically changes with the peak value of the source voltage VCS. The power tube Q1 will not be damaged due to the excessive increase, and the opening will not be incomplete due to the insufficient driving voltage. At the same time, with the increase of the gate-source voltage VGS, the on-resistance of the power tube Q1 will decrease, thereby reducing the on-resistance loss of the power tube Q1 and improving the working efficiency.

[0142] In some embodiments, the driving current control module 120 can include a valley bottom counting module 160, a voltage comparison module 170, and a control signal generation module 180.

[0143] In this embodiment, the input terminal of the valley counting module 160 is configured to receive the valley signal, and the output terminal of the valley counting module 160 is configured to output the number of valleys in the current switching cycle.

[0144] One input terminal of the voltage comparison module 170 is configured to receive a feedback voltage, the other input terminal of the voltage comparison module 170 is configured to receive a target voltage threshold, and the output terminal of the voltage comparison module 170 is configured to output a first comparison signal.

[0145] The voltage comparison module 170 can output a first comparison signal based on the magnitude of the feedback voltage and the target voltage threshold. The first comparison signal can be a high level or a low level.

[0146] The input terminal of the control signal generation module 180 is connected to the output terminal of the valley counting module 160 and the output terminal of the voltage comparison module 170, respectively. The output terminal of the control signal generation module 180 is configured to output the first control signal.

[0147] like Figure 13 As shown, in some embodiments, the valley counting module 160 may include a counter 190, a latch 200, and a decoding circuit 210.

[0148] In this embodiment, the input of counter 190 is configured to receive the valley signal, and counter 190 can output a signal of D<2:0>.

[0149] The input terminal of latch 200 is connected to the output terminal of counter 190, and latch 200 can output the signal L<2:0>.

[0150] The input terminals of the decoding circuit 210 are connected to the output terminals of the counter 190 and the latch 200, respectively. The output terminal of the decoding circuit 210 is configured to output the valley number of the valley signal within the current switching cycle. The decoding circuit 210 can translate signals D<2:0> and L<2:0> into the signal Val_count, which represents the valley number of the valley signal within the current switching cycle. Figure 12 As shown, V DS The signal has three valleys. The valley signal is sent to the valley counting module 160. The final output signal Val_count of the valley counting module 160 is 3.

[0151] like Figure 15 As shown, in some embodiments, the first control signal includes a first sub-control signal, a second sub-control signal, and a third sub-control signal; the control signal generation module 180 may include: a first inverter INV1, a NOR circuit NOR1, a NAND circuit NAND1, and a second inverter INV2.

[0152] In this embodiment, the input terminal of the first inverter INV1 is connected to the output terminal of the voltage comparison module 170, and the output terminal of the first inverter INV1 is configured to output the first sub-control signal LC.

[0153] When the Vcomp signal is low, the Vcomp signal passes through the first inverter INV1, and the output control logic signal LC is high.

[0154] One input of the NOR1 circuit is connected to the output of the first inverter INV1, and the other input of the NOR1 circuit is connected to the output of the valley counting module 160. The output of the NOR1 circuit is configured to output the second sub-control signal MC.

[0155] When the Vcomp signal is low, the second sub-control signal MC is low.

[0156] One input terminal of the NAND1 circuit is connected to the output terminal of the voltage comparator module 170, and the other input terminal of the NAND1 circuit is connected to the output terminal of the valley counting module 160.

[0157] The input of the second inverter INV2 is connected to the output of the NAND circuit NAND1, and the output of the second inverter INV2 is configured to output the third sub-control signal HC.

[0158] When the Vcomp signal is low, the third sub-control signal HC is low.

[0159] When Vcomp signal is high and Val_count is low, the second sub-control signal MC is high and the third sub-control signal HC is low.

[0160] When Vcomp signal is high and Val_count is high, the second sub-control signal MC is low and the third sub-control signal HC is high.

[0161] In actual operation, the feedback voltage can be connected to the non-inverting input of the voltage comparison module 170, and the target voltage threshold can be connected to the inverting input of the voltage comparison module 170, such as... Figure 11 As shown, when the feedback voltage VFB is less than the target voltage threshold VREF2, it can be determined that the switching power supply system has entered standby mode. At this time, the system operating frequency is low, the signal Vcomp output by the voltage comparator module 170 is low, the first sub-control signal LC output by the first inverter INV1 is high, the second sub-control signal MC output by the NOR1 circuit and the third sub-control signal HC output by the second inverter INV2 are low, and weak current drive can be used.

[0162] When the feedback voltage VFB is greater than the target voltage threshold VREF2, it can be determined that the switching power supply system has not entered standby mode and the system is working normally. When the system is working normally, the ZCD pin can sample the valley signal and send the valley signal sampled by the ZCD pin to the valley counting module 160.

[0163] When the feedback voltage VFB is greater than the target voltage threshold VREF2, the signal Vcomp output by the voltage comparator module 170 is high, and the control logic signal LC output by the first inverter INV1 is low. When the number of valleys in the valley signal is greater than the set value (e.g., 3 to 5), it indicates that the load is light or the input voltage is low. At this time, the signal Val_count output by the valley counter module 160 is low, the second sub-control signal MC output by the NOR circuit NOR1 is high, and the third sub-control signal HC output by the second inverter INV2 is low, and a medium drive current can be used.

[0164] If the feedback voltage VFB is greater than the target voltage threshold VREF2 and the number of valleys in the valley signal is less than the set value (e.g., 3-5), it indicates that the load is heavy or the input voltage is large. At this time, the valley counting module 160 outputs the signal Val_count high, the second sub-control signal MC output by the NOR1 circuit is low, and the third sub-control signal HC output by the second inverter INV2 is high, and a strong drive current can be used.

[0165] like Figure 16 As shown, in some embodiments, the control signal generation module 180 may include: a third inverter INV3, a first flip-flop 220, a fourth inverter INV4, and a second flip-flop 230.

[0166] In this embodiment, the input terminal of the third inverter INV3 is connected to the output terminal of the voltage comparator module 170, and the output terminal of the third inverter INV3 is configured to output the first sub-control signal LC.

[0167] The first input terminal RST of the first flip-flop 220 is connected to the output terminal of the voltage comparison module 170, the second input terminal CLK of the first flip-flop 220 is connected to the output terminal of the valley counting module 160, and the output terminal Q of the first flip-flop 220 is configured to output the second sub-control signal MC.

[0168] The input of the fourth inverter INV4 is connected to the output of the valley counting module 160.

[0169] The third input end RST of the second flip-flop 230 is connected with the output end of the voltage comparison module 170, the fourth input end CLK of the second flip-flop 230 is connected with the output end of the fourth inverter INV4, and the output end Q of the second flip-flop 230 is configured to output the third sub-control signal HC.

[0170] In actual execution, when the feedback voltage VFB is less than the target voltage threshold VREF2, the signal Vcomp output by the voltage comparison module 170 is low, the first sub-control signal LC output by the third inverter INV3 is high, the second sub-control signal MC output by the first flip-flop 220 and the third sub-control signal HC output by the second flip-flop 230 are low, and the switching power supply system will adopt weak current driving.

[0171] When the feedback voltage VFB is greater than the target voltage threshold VREF2, the signal Vcomp output by the voltage comparison module 170 is high, and when the ZCD valley number is greater than the set value, the signal Val_count output by the valley counting module 160 becomes low, the first flip-flop 220 samples the falling edge change of Val_count, and outputs the second sub-control signal MC as high. The first sub-control signal LC output by the third inverter INV3 is low, the second flip-flop 230 cannot sample the rising edge signal, and the third sub-control signal HC output is low. The switching power supply system will adopt medium current driving.

[0172] When the ZCD valley number is less than the set value, the signal Val_count output by the valley counting module 160 becomes high, the second flip-flop 230 samples the rising edge change of Val_count, and outputs the third sub-control signal HC as high. The first sub-control signal LC output by the third inverter INV3 is low, the first flip-flop 220 cannot sample the falling edge signal, and the second sub-control signal MC output is low. The switching power supply system will adopt strong current driving.

[0173] As shown in FIG. 1, Figure 14 In some embodiments, the driving module 130 can include a first driving circuit, a second driving circuit, and a third driving circuit.

[0174] In this embodiment, the circuit structures of the first driving circuit, the second driving circuit, and the third driving circuit are the same, and the received control signals are different.

[0175] The first driving circuit, the second driving circuit, and the third driving circuit are connected in parallel.

[0176] The first driving circuit, the second driving circuit, and the third driving circuit are configured to be selectively turned on based on the first control signal.

[0177] In some embodiments, the driving circuit can comprise: an AND circuit, a target switch and a driving tube.

[0178] In this embodiment, the first driving circuit can comprise a first AND circuit 240, a first switch S1 and a first driving tube N1; the second driving circuit can comprise a second AND circuit 250, a second switch S2 and a second driving tube N2; and the third driving circuit can comprise a third AND circuit 260, a third switch S3 and a third driving tube N3.

[0179] One input end of the AND circuit is configured to receive a first control signal, and the other input end of the AND circuit is configured to receive a conduction control signal.

[0180] For example, one input end of the first AND circuit 240 can receive a first sub-control signal LC, one input end of the second AND circuit 250 can receive a second sub-control signal MC, and one input end of the third AND circuit 260 can receive a third sub-control signal HC.

[0181] One end of the target switch is connected to the output end of the AND circuit, and the voltage at the one end of the target switch is the first driving voltage.

[0182] The gate of the driving tube is connected to the other end of the target switch, and the drain of the driving tube is connected to the gate of the power tube Q1.

[0183] In actual implementation process, as shown in Figure 14 When it is needed to turn on the power tube Q1, the conduction control signal Gate_on becomes high level.

[0184] When the feedback voltage VFB is less than the target threshold voltage VREF2, the switching power supply system enters standby mode, the first sub-control signal LC becomes high level, the second sub-control signal MC is low level, and the third sub-control signal HC is low level, the first switch S1 is closed, the second switch S2 is opened, and the third switch S3 is opened, the first driving voltage VDRV_IN is input to the gate of the first driving tube N1, the first driving tube N1 is turned on, and the power tube Q1 is driven by the current I1, and the target driving voltage DRV of the power tube Q1 is about VDRV_IN-Vth1;

[0185] When the feedback voltage VFB is greater than the target threshold voltage VREF2, and the trough number of the trough signal is greater than the set value, the second sub-control signal MC is high level, the first sub-control signal LC and the third sub-control signal HC are low level, the second switch S2 is closed, the first switch S1 and the third switch S3 are opened, the first driving voltage VDRV_IN is input to the gate of the second driving tube N2, the second driving tube N2 is turned on, and the power tube Q1 is driven by the current I2, and the target driving voltage DRV of the power tube Q1 is about VDRV_IN-Vth2;

[0186] In a case where the feedback voltage VFB is greater than the target threshold voltage VREF2 and the trough number of the trough signal is less than a set value, the third sub-control signal HC is at a high level, the first sub-control signal LC and the second sub-control signal MC are at low levels, the third switch S3 is closed, the first switch S1 and the second switch S2 are opened, the first driving voltage VDRV IN is input to the gate of the third driving tube N3, the third driving tube N3 is turned on, and the power tube Q1 is driven by the current I3, and the target driving voltage DRV is approximately VDRV IN-Vth3.

[0187] The first driving tube N1, the second driving tube N2, and the third driving tube N3 are of the same type and have the same threshold voltage, that is, the target driving voltage DRV is VDRV IN-Vth, and the driving currents I1, I2, and I3 can be achieved by changing the size of the first driving tube N1, the second driving tube N2, and the third driving tube N3, where I3>I2>I1.

[0188] In some embodiments, the driving module 130 can include an inverter and a driving tube.

[0189] In this embodiment, the input end of the inverter is configured to receive the conduction control signal, and the output end of the inverter is connected to the gate of the driving tube.

[0190] The source of the driving tube is grounded, and the drain of the driving tube is connected to the DRV pin.

[0191] The first driving circuit, the second driving circuit, and the third driving circuit are used to control the DRV signal to be high, and the inverter and the driving tube are used to control the DRV signal to be low.

[0192] The embodiments of the present application also provide a switching power supply system.

[0193] In some embodiments, the switching power supply system can include a primary side circuit, a secondary side circuit, and an auxiliary circuit.

[0194] In this embodiment, the primary side circuit can include a power tube Q1 and a driving control circuit of the power tube.

[0195] The power tube Q1 can be arranged outside the driving control circuit of the power tube, or the power tube Q1 and the driving control circuit of the power tube can be packaged together, which can be selected based on user needs, and the present application is not limited.

[0196] As Figure 4 The switching power supply system with the external power tube Q1 is exemplified, and the primary side circuit includes a primary side winding Np, the power tube Q1, and a primary side control circuit.

[0197] The primary side control circuit includes a driving control circuit of the driving tube.

[0198] The non-signature terminal of the primary winding Np is configured to receive the input voltage, and the same-signature terminal is connected to the drain of the power transistor Q1. The two ends of the primary winding Np are connected to resistor R1, capacitor C1 and rectifier D1 to form an RCD spike absorption circuit. The source of the power transistor Q1 is grounded through the primary current sampling resistor RCS. The gate of the power transistor Q1 is connected to the DRV pin of the primary control circuit. The input voltage Vbulk provides the start-up voltage to the chip after passing through the current limiting resistor R0.

[0199] The secondary circuit includes the secondary winding Ns, the output rectifier D2, and the light-emitting diode I1A.

[0200] The non-polarized terminal of the secondary winding Ns is grounded, and the same-polarized terminal is connected to the anode of the output rectifier diode D2. The cathode of the output rectifier diode D2 is connected to the output capacitor C2 to provide the output voltage Vout.

[0201] The output voltage Vout is input to the TL431 through sampling resistors R3 and R4. The output current of the TL431 is fed back to the primary side FB pin through an optocoupler composed of LED I1A and primary side phototransistor I1B.

[0202] The auxiliary circuit includes an auxiliary winding Na, a diode D3, and a capacitor C4, which provides the chip with a power supply voltage VDD.

[0203] The auxiliary winding Na2 is grounded at the opposite end and connected to the sampling resistors RH and RL at the same end to input the sampled voltage signal to the ZCD pin of the primary chip to detect the input voltage.

[0204] like Figure 6 An example of a switching power supply system is shown, in which the power transistor Q1 and the controller are packaged together. The primary circuitry includes the primary winding Np and the primary control circuitry.

[0205] The primary-side control circuit includes power transistor Q1 and the power transistor's drive control circuit.

[0206] The primary winding Np is connected to the input voltage at the opposite end and to the Drain pin of the control circuit at the same end. The primary winding Np is connected to resistor R1, capacitor C1 and rectifier diode D1 to form an RCD spike absorption circuit. The CS pin of the control circuit is grounded through the primary current sampling resistor RCS. The input voltage Vbulk provides the start-up voltage to the chip after passing through the current limiting resistor R0.

[0207] Figure 6 The structure of the example secondary circuit is similar to Figure 4 The secondary circuit structure is the same as in the example, so it will not be described in detail here.

[0208] The embodiments of the present application are described above with reference to the drawings, but the present application is not limited to the specific embodiments described above, and the specific embodiments described above are merely illustrative, not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, all of which belong to the protection of the present application.

[0209] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an illustrative embodiment", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0210] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A drive control circuit for a power transistor, characterized in that, include: A drive voltage control module, wherein the input terminal of the drive voltage control module is configured to receive the feedback voltage of the circuit where the power transistor is located, and the output terminal of the drive voltage control module is configured to output a first drive voltage based on the feedback voltage of a first multiple; A drive current control module is provided, wherein the input terminal of the drive current control module is configured to receive the feedback voltage and the valley signal corresponding to the power transistor, and the output terminal of the drive current control module is configured to output a first control signal; the valley signal is used to characterize the waveform oscillation of the source terminal voltage of the power transistor to the lowest point. The driving module has its input terminals connected to the output terminals of the driving voltage control module and the driving current control module, respectively, and its output terminal connected to the gate of the power transistor. The driving module is configured to convert the first driving voltage into a target driving voltage and the first control signal into a driving current to drive the power transistor to operate.

2. The power transistor drive control circuit according to claim 1, characterized in that, The drive voltage control module includes: A proportional circuit, wherein the input terminal of the proportional circuit is configured to receive the feedback voltage, and the output terminal of the proportional circuit is configured to output the feedback voltage of the first multiple; A low-dropout linear regulator, wherein the output of the low-dropout linear regulator is configured to output a fixed voltage; A voltage adder module, wherein the input terminal of the voltage adder module is connected to the output terminal of the proportional circuit and the output terminal of the low dropout linear regulator, and the voltage adder module is configured to output the first driving voltage.

3. The power transistor drive control circuit according to claim 2, characterized in that, The proportional circuit includes: A first resistor, a second resistor, and a third resistor are connected in series. One end of the first resistor is connected to a first terminal, and the other end of the first resistor is configured to receive the feedback voltage. The first terminal is configured to receive a voltage source signal. The end of the second resistor closest to the first resistor is configured to receive the feedback voltage. The end of the third resistor furthest from the second resistor is grounded. The voltage across the third resistor is a multiple of the first feedback voltage.

4. The power transistor drive control circuit according to claim 2, characterized in that, The proportional circuit includes: A fourth resistor, one end of which is grounded, and the other end of which is configured to receive the feedback voltage; The first transistor, the drain of which is connected to the other end of the fourth resistor; The second transistor has a current that is a second multiple of the current of the first transistor; A fifth resistor and a sixth resistor are connected in series, with one end of the fifth resistor connected to the drain of the second transistor; the end of the sixth resistor away from the fifth resistor is grounded, and the end of the sixth resistor away from the fifth resistor is connected to one end of the fourth resistor; The voltage across the sixth resistor is a multiple of the first feedback voltage.

5. The power transistor drive control circuit according to any one of claims 1-4, characterized in that, The drive current control module includes: A valley counting module, wherein the input terminal of the valley counting module is configured to receive the valley signal, and the output terminal of the valley counting module is configured to output the valley number of the valley signal in the current switching cycle; A voltage comparison module, wherein one input terminal of the voltage comparison module is configured to receive the feedback voltage, the other input terminal of the voltage comparison module is configured to receive a target voltage threshold, and the output terminal of the voltage comparison module is configured to output a first comparison signal; A control signal generation module is provided, wherein the input terminal of the control signal generation module is connected to the output terminal of the valley counting module and the output terminal of the voltage comparison module, respectively, and the output terminal of the control signal generation module is configured to output the first control signal.

6. The power transistor drive control circuit according to claim 5, characterized in that, The valley bottom counting module includes: A counter, the input of which is configured to receive the valley signal; A latch, wherein the input terminal of the latch is connected to the output terminal of the counter; A decoding circuit, the input of which is connected to the output of the counter and the output of the latch, respectively, and the output of which is configured to output the valley number of the valley signal in the current switching cycle.

7. The power transistor drive control circuit according to claim 5, characterized in that, The first control signal includes a first sub-control signal, a second sub-control signal, and a third sub-control signal; the control signal generation module includes: A first inverter, the input of which is connected to the output of the voltage comparison module, and the output of which is configured to output the first sub-control signal; A NOR circuit, wherein one input terminal of the NOR circuit is connected to the output terminal of the first inverter, the other input terminal of the NOR circuit is connected to the output terminal of the valley counting module, and the output terminal of the NOR circuit is configured to output the second sub-control signal; A NAND circuit, wherein one input terminal of the NAND circuit is connected to the output terminal of the voltage comparison module, and the other input terminal of the NAND circuit is connected to the output terminal of the valley counting module; A second inverter, the input of which is connected to the output of the NAND circuit, is configured to output the third sub-control signal.

8. The power transistor drive control circuit according to claim 5, characterized in that, The first control signal includes a first sub-control signal, a second sub-control signal, and a third sub-control signal; the control signal generation module includes: The third inverter, the input of which is connected to the output of the voltage comparison module, is configured to output the first sub-control signal; A first trigger, wherein the first input terminal of the first trigger is connected to the output terminal of the voltage comparison module, the second input terminal of the first trigger is connected to the output terminal of the valley counting module, and the output terminal of the first trigger is configured to output the second sub-control signal; The fourth inverter, the input of which is connected to the output of the valley counting module; The second flip-flop has its third input connected to the output of the voltage comparison module, its fourth input connected to the output of the fourth inverter, and its output configured to output the third sub-control signal.

9. The power transistor drive control circuit according to any one of claims 1-4, characterized in that, The driving module includes: First driving circuit; A second driving circuit is connected in parallel with the first driving circuit. A third driving circuit is connected in parallel with the first driving circuit and the second driving circuit, respectively. The first driving circuit, the second driving circuit, and the third driving circuit are configured to selectively conduct based on the first control signal.

10. The power transistor drive control circuit according to claim 9, characterized in that, The drive circuit includes: An AND circuit, wherein one input terminal of the AND circuit is configured to receive the first control signal, and the other input terminal of the AND circuit is configured to receive a conduction control signal; A target switch, one end of which is connected to the output terminal of the circuit, and the voltage at one end of the target switch is the first driving voltage; A driving transistor, the gate of which is connected to the other end of the target switch, and the drain of which is connected to the gate of the power transistor.

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