Dead time circuit and GaN driving chip

Abstract

The embodiment of the invention provides a dead time circuit and a GaN driving chip, and relates to the technical field of power tube driving circuits. When a driving source signal of a power tube is converted from representing turn-off to representing turn-on, the current generation module charges the capacitor module, an output signal of the threshold triggering module can be turned over when the charging reaches the threshold triggering module, the output signal of the threshold triggering module is connected to a grid electrode of the power tube, and the time for charging to a threshold is dead time. And when the driving signals of the high-side power tube and the low-side power tube are overturned, the current generation module generates current under the action of energy storage of an inductor in the load module. When the inductance in the load module changes, the current generated by the current generation module changes, and then the charging time and the dead time are changed, that is, the dead time can change along with the inductance change of the load module.

Description

Technical Field

[0001] The present application relates to the technical field of power tube drive circuits, and in particular to dead time circuits and GaN drive chips. Background Art

[0002] The advantages of GaN devices have promoted the development of high-frequency, high-efficiency, and high-performance GaN driver chips, making GaN widely used in the field of power electronics. The basic structure of an enhanced GaN driver chip contains two channels: a high-side channel and a low-side channel. In the high-voltage drive circuit, the high-side channel and the low-side channel need to use independent gate drive circuits. In addition, a high-voltage isolation structure is required on the high side during process manufacturing. These factors may cause the delay paths of the gate input signals of the high-side and low-side power tubes to no longer match.

[0003] When the delay of the high-side channel and the low-side channel of the driving circuit is mismatched, the high-side and low-side power tubes may produce a shoot-through phenomenon during commutation, so dead time is usually inserted between the gate drive signals of the high-side and low-side power tubes to ensure that the circuit can commutate safely and reliably. Dead time refers to the delay between the effective input signals of the gates of the high-side power tube and the low-side power tube, and refers to the time when both the high-side and low-side power tubes are not conducting.

[0004] If the dead time is too long, it will cause reverse conduction loss of the power tube; if the dead time is too short, shoot-through may occur, which will generate a large current, that is, hard switching loss problem.

[0005] The ideal dead time setting method changes with the load conditions. The optimal dead time for different loads is different. How to design a dead time circuit that can adaptively adjust the dead time size as the load changes becomes a design difficulty. Summary of the invention

[0006] The purpose of this application is to provide a dead time circuit and a GaN driver chip to solve the technical problem of how to design a dead time circuit that adaptively adjusts the dead time size as the load changes.

[0007] To achieve the above objectives, one or more embodiments of the present application adopt the following technical solutions.

[0008] In a first aspect, the present application provides a dead time circuit, which is applied to a power tube circuit, wherein the power tube circuit includes a bus, a high-side power tube and a low-side power tube, wherein the bus, the high-side power tube, the low-side power tube and a ground are connected in sequence; a connection point between the high-side power tube and the low-side power tube is used to connect a load module; and the load module includes an inductor;

[0009] The dead time circuit includes a bootstrap module, a first current generating module, a first signal transfer module, a first capacitor module and a first threshold triggering module;

[0010] The first end of the bootstrap module is connected to the connection point of the high-side power tube and the low-side power tube, the second end of the bootstrap module is connected to the positive power supply end of the first current generating module, and the negative power supply end of the first current generating module is grounded; the current output end of the first current generating module is connected to the first end of the first capacitor module through the first signal transfer module, and the second end of the first capacitor module is grounded;

[0011] The input end of the first signal transfer module is used to connect the driving signal source of the high-side power tube;

[0012] The output end of the first signal transfer module is connected to the first end of the first capacitor module;

[0013] A first end of the first capacitor module is connected to an input end of the first threshold trigger module;

[0014] The output end of the first threshold trigger module is used to connect the gate of the high-side power tube;

[0015] When the voltage at the first terminal of the bootstrap module increases, the voltage at the second terminal of the bootstrap module increases simultaneously; when the voltage at the second terminal of the bootstrap module increases, the current generated by the first current generating module increases;

[0016] When the driving signal source of the high-side power tube sends a signal to turn on the high-side power tube, the first signal transfer module charges the first capacitor module with the current generated by the first current generation module; when the first capacitor module is charged to a voltage reaching the threshold of the first threshold trigger module, the output signal of the first threshold trigger module is flipped;

[0017] When the driving signal source of the high-side power tube sends a signal to cut off the high-side power tube, the first signal relay module causes the first capacitor module to discharge to the ground; when the first capacitor module is discharged until the voltage reaches the threshold of the first threshold trigger module, the output signal of the first threshold trigger module is flipped.

[0018] The following takes an implementation as an example to discuss the beneficial effects from the perspective of principle:

[0019] In this implementation, the low level of the driving signal indicates that the power tube is turned off, and the high level of the driving signal indicates that the power tube is turned on; when the voltage of the first capacitor module is higher than the threshold of the first threshold trigger module, the first threshold trigger module triggers a high level output; when the voltage of the first capacitor module is lower than the threshold of the first threshold trigger module, the first threshold trigger module triggers a low level output; the voltage at the connection point between the high-side power tube and the low-side power tube is recorded as V SW ;

[0020] Assume that the driving signal of the high-side power tube is at a low level, and the driving signal of the low-side power tube is at a high level; at this time, the first current generating module generates a certain current to power the first signal relay module, and the first signal relay module conducts the first capacitor module to the ground; since the voltage of the first capacitor module is small, the first threshold trigger module does not trigger a high-level output, so the first threshold trigger module outputs a low level through the switching circuit to the high-side power tube, and the high-side power tube is cut off;

[0021] When the driving signal of the low-side power tube changes from high level to low level, the low-side power tube is quickly turned off. Due to the effect of the inductor freewheeling in the load module, V SW Will quickly rise to the bus voltage, V SW A positive dv / dt is formed. When the voltage at the first end of the bootstrap module increases, the voltage at the second end of the bootstrap module increases at the same time. The current generated by the first current generating module increases, and the signal input by the first signal transfer module becomes a high level. The first signal transfer module charges the first capacitor module with the current generated by the first current generating module. When the voltage of the first capacitor module reaches the threshold of the first threshold trigger module, the output signal of the first threshold trigger module flips. This charging time is the high-side dead time. The charging time is related to the charging current of the first capacitor module, and the charging current is related to V SW Related, V SW It is related to the inductance in the load module, that is, changes in the inductance, current, etc. in the load module will cause adaptive changes in the high-side dead time of the high-side power tube.

[0022] In a second aspect, the present application provides a dead time circuit, which is applied to the power tube circuit described in the first aspect, and the dead time circuit includes a second current generating module, a second signal transfer module, a second capacitor module and a second threshold triggering module;

[0023] The connection point of the high-side power tube and the low-side power tube is connected to the negative power supply terminal of the second current generating module, the positive power supply terminal of the second current generating module is connected to the power supply, the current output terminal of the second current generating module is connected to the first end of the second capacitor module through the second signal transfer module, and the second end of the second capacitor module is grounded;

[0024] The input end of the second signal transfer module is used to connect the driving signal source of the low-side power tube;

[0025] The output end of the second signal transfer module is connected to the first end of the second capacitor module;

[0026] A first end of the second capacitor module is connected to an input end of the second threshold trigger module;

[0027] The output end of the second threshold trigger module is used to connect the gate of the low-side power tube;

[0028] When the voltage at the connection point between the high-side power tube and the low-side power tube decreases, the current generated by the second current generating module increases;

[0029] When the driving signal source of the low-side power tube sends a signal to turn on the low-side power tube, the second signal transfer module charges the second capacitor module with the current generated by the second current generating module; when the second capacitor module is charged to a voltage reaching the threshold of the second threshold trigger module, the output signal of the second threshold trigger module flips;

[0030] When the driving signal source of the low-side power tube sends a signal to cut off the low-side power tube, the second signal transfer module causes the second capacitor module to discharge to the ground; when the second capacitor module is discharged until the voltage reaches the threshold of the second threshold trigger module, the output signal of the second threshold trigger module is flipped.

[0031] Regarding the beneficial effects, the principles are similar to those described in the first aspect:

[0032] When the driving signal of the high-side power tube changes from high level to low-high level, the high-side power tube is quickly turned off. Due to the effect of the inductor freewheeling in the load module, V SW Will drop rapidly, V SW A negative dv / dt is formed, the current generated by the second current generating module becomes larger, the signal input by the second signal transfer module becomes high level, and the second signal transfer module uses the current generated by the second current generating module to charge the second capacitor module. When the second capacitor module is charged to a voltage reaching the threshold of the second threshold trigger module, the output signal of the second threshold trigger module flips, and this charging time is the low-side dead time. The charging time is related to the charging current of the second capacitor module, and the charging current is related to V SW Related, V SW It is related to the inductance in the load module, that is, changes in the inductance, current, etc. in the load module will cause adaptive changes in the low-side dead time.

[0033] In a third aspect, the present application provides a GaN driver chip, the GaN driver chip comprising the dead time circuit described in the first aspect or the second aspect. The load module comprises an inductor, for example, the load module comprises a Buck circuit, and the Buck circuit comprises an inductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of a power tube circuit;

[0036] Figure 2 A schematic diagram of a high-side dead time circuit provided in an embodiment of the present application;

[0037] Figure 3 A schematic diagram of a low-side dead time circuit provided in an embodiment of the present application;

[0038] Figure 4 A bootstrap module provided in the embodiment of the present application includes a bootstrap capacitor C Boot and bootstrap diode D Boot Schematic diagram of

[0039] Figure 5 A schematic diagram of forming opposite drive signals from the same PWM signal provided in an embodiment of the present application;

[0040] Figure 6 A schematic diagram of an anti-straight-through protection module provided in an embodiment of the present application;

[0041] Figure 7 A schematic diagram of a first current generating module provided in an embodiment of the present application;

[0042] Figure 8 A schematic diagram of a second current generating module provided in an embodiment of the present application;

[0043] Fig. 9 A schematic diagram of a high-side dead time principle provided in an embodiment of the present application;

[0044] Fig.10 A schematic diagram of a low-side dead time principle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described in the drawings here can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0047] In the description of this application, it should be noted that:

[0048] Relational terms such as first and second, etc., are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations;

[0049] “Connection” should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0050] like Figure 1 , Figure 1 A power tube circuit is shown, which can be a structure in an enhanced GaN driver chip. The power tube circuit includes a bus, a high-side power tube M H And low side power tube M L , V in the figure BUS is the bus voltage, bus, high side power tube M H And low side power tube M L and ground GND in turn; high-side power tube M H And low side power tube M L The connection point is denoted as the switch node, and the switch node voltage is denoted as V SW , the switch node is used to connect the load module; the load module includes an inductor and a load.

[0051] The dead time circuit of the present application is applied to a power tube circuit. Figure 2 A high-side dead time circuit is presented, which includes a bootstrap module, a first current generating module, a first signal transfer module, a first capacitor module and a first threshold triggering module.

[0052] The first end of the bootstrap module is connected to the connection point of the high-side power tube and the low-side power tube, the second end of the bootstrap module is connected to the positive power supply end of the first current generating module, and the negative power supply end of the first current generating module is grounded; when the voltage of the first end of the bootstrap module becomes high, the voltage of the second end of the bootstrap module also becomes high.

[0053] The current output end of the first current generating module is connected to the first end of the first capacitor module through the first signal transfer module. When the voltage of the second end of the bootstrap module becomes higher, that is, the voltage of the positive power supply end of the first current generating module becomes higher, the current generated by the first current generating module becomes larger. The second end of the first capacitor module is grounded.

[0054] The input end of the first signal transfer module is used to connect to the driving signal source of the high-side power tube and receive the driving signal HIN of the high-side power tube; the output end of the first signal transfer module is connected to the first end of the first capacitor module; when the driving signal source of the high-side power tube sends a signal to turn on the high-side power tube, the first signal transfer module charges the first capacitor module with the current generated by the first current generating module, and the current generated by the first current generating module affects the charging speed of the first capacitor module.

[0055] The first end of the first capacitor module is connected to the input end of the first threshold trigger module; when the first capacitor module is charged to a voltage that reaches the threshold of the first threshold trigger module, the output signal of the first threshold trigger module is flipped. Conversely, when the driving signal source of the high-side power tube sends a signal to cut off the high-side power tube, the first signal transfer module discharges the first capacitor module to the ground; when the first capacitor module is discharged to a voltage that reaches the threshold of the first threshold trigger module, the output signal of the first threshold trigger module is flipped.

[0056] The output end of the first threshold trigger module is used to connect to the gate of the high-side power tube. The output end of the first threshold trigger module can be connected to the gate of the high-side power tube through the high-side driving module.

[0057] The following takes an implementation as an example to discuss the beneficial effects from the perspective of principle. In this implementation, a low level driving signal indicates that the power tube is turned off, and a high level driving signal indicates that the power tube is turned on; when the voltage of the first capacitor module is higher than the threshold of the first threshold trigger module, the first threshold trigger module triggers a high level output; when the voltage of the first capacitor module is lower than the threshold of the first threshold trigger module, the first threshold trigger module triggers a low level output. In other implementations, the high and low levels may be opposite;

[0058] Assume that the driving signal of the high-side power tube is at a low level, and the driving signal of the low-side power tube is at a high level; at this time, the first current generating module generates a certain current to power the first signal relay module, and the first signal relay module conducts the first capacitor module to the ground; since the voltage of the first capacitor module is small, the first threshold trigger module does not trigger a high-level output, so the first threshold trigger module outputs a low level through the switching circuit to the high-side power tube, and the high-side power tube is cut off;

[0059] When the driving signal of the high-side power tube changes from low level to high level, the low-side power tube is quickly turned off. Due to the effect of the inductor freewheeling in the load module, V SW Will quickly rise to the bus voltage, V SWA positive dv / dt is formed. When the voltage at the first end of the bootstrap module increases, the voltage at the second end of the bootstrap module increases at the same time. The current generated by the first current generating module increases, and the signal input by the first signal transfer module becomes a high level. The first signal transfer module charges the first capacitor module with the current generated by the first current generating module. When the voltage of the first capacitor module reaches the threshold of the first threshold trigger module, the output signal of the first threshold trigger module flips. This charging time is the high-side dead time. The charging time is related to the charging current of the first capacitor module, and the charging current is related to V SW Related, V SW It is related to the inductance in the load module, that is, changes in the inductance, current, etc. in the load module will cause adaptive changes in the high-side dead time of the high-side power tube.

[0060] The above high-side dead time circuit can realize adaptive change of the high-side dead time. Figure 3 A low-side dead time circuit for realizing adaptive change of low-side dead time is presented. The low-side dead time circuit includes a second current generating module, a second signal transfer module, a second capacitor module and a second threshold triggering module.

[0061] The connection point of the high-side power tube and the low-side power tube is connected to the negative power supply terminal of the second current generating module, and the positive power supply terminal of the second current generating module is connected to the power supply VDD. The power supply VDD can be a power supply that simultaneously supplies power to the first current generating module, the first signal transfer module, the first threshold trigger module, the second current generating module, the second signal transfer module, and the second threshold trigger module. When the voltage at the negative power supply terminal of the second current generating module decreases, the current output by the second current generating module increases.

[0062] The current output end of the second current generating module is connected to the first end of the second capacitor module through the second signal transfer module, and the second end of the second capacitor module is grounded.

[0063] The input end of the second signal transfer module is used to connect to the driving signal source of the low-side power tube and receive the driving signal LIN of the low-side power tube; the output end of the second signal transfer module is connected to the first end of the second capacitor module; when the driving signal source of the low-side power tube sends a signal to turn on the low-side power tube, the second signal transfer module charges the second capacitor module with the current generated by the second current generating module, and the current generated by the second current generating module affects the charging speed of the second capacitor module.

[0064] The first end of the second capacitor module is connected to the input end of the second threshold trigger module; when the second capacitor module is charged to a voltage that reaches the threshold of the second threshold trigger module, the output signal of the second threshold trigger module is flipped. Conversely, when the driving signal source of the low-side power tube sends a signal to cut off the low-side power tube, the second signal transfer module discharges the second capacitor module to the ground; when the second capacitor module is discharged to a voltage that reaches the threshold of the second threshold trigger module, the output signal of the second threshold trigger module is flipped.

[0065] The output end of the second threshold trigger module is used to connect to the gate of the low-side power tube. The output end of the second threshold trigger module can be connected to the gate of the low-side power tube through the low-side driving module.

[0066] Similar to the high-side dead time circuit, the principle of the low-side dead time circuit is as follows:

[0067] When the driving signal of the low-side power tube changes from low level to high level, the high-side power tube is quickly turned off. Due to the effect of the inductor freewheeling in the load module, V SW Will drop rapidly, V SW A negative dv / dt is formed, the current generated by the second current generating module becomes larger, the signal input by the second signal transfer module becomes high level, and the second signal transfer module uses the current generated by the second current generating module to charge the second capacitor module. When the second capacitor module is charged to a voltage reaching the threshold of the second threshold trigger module, the output signal of the second threshold trigger module flips, and this charging time is the low-side dead time. The charging time is related to the charging current of the second capacitor module, and the charging current is related to V SW Related, V SW It is related to the inductance in the load module, that is, changes in the inductance, current, etc. in the load module will cause adaptive changes in the low-side dead time.

[0068] The high-side dead time circuit and the low-side dead time circuit mentioned above can be combined, and the high-side dead time circuit and the low-side dead time circuit are simultaneously applied to the power tube circuit.

[0069] like Figure 4 The first current generating module, the first signal transfer module, the first capacitor module, the first threshold triggering module, the second current generating module, the second signal transfer module, the second capacitor module and the second threshold triggering module constitute a dead time circuit module. The high side driving module may include a level shifter and a buffer, and the low side driving module may also include a level shifter and a buffer. Figure 4 The bootstrap module can include a bootstrap capacitor C Boot and bootstrap diode D Boot . Bootstrap diode D Boot The anode of the capacitor can be connected to the power supply VDD, the bootstrap capacitor C Boot and bootstrap diode DBoot The connection point is the high-side floating source VDDH, the bootstrap capacitor C Boot and bootstrap diode D Boot The connection point voltage can be greater than the power supply VDD.

[0070] like Figure 5 , Figure 5 In the embodiment, the high-side delay adjustment module includes a first signal transfer module, a first capacitor module and a first threshold trigger module, and the low-side delay adjustment module includes a second current generation module, a second signal transfer module, a second capacitor module and a second threshold trigger module. An anti-straight-through protection module can be added at the input position of the first signal transfer module and the second signal transfer module. The anti-straight-through protection module is used to prevent the first signal transfer module and the second signal transfer module from inputting a high level at the same time. The anti-straight-through protection module can include a logic gate. Figure 6 The anti-shoot-through protection module may include an XOR gate XOR1, an AND gate AND1 and an AND gate AND2, and the output signals A1_OUT and A2_OUT are not high level at the same time.

[0071] like Figure 5 The driving signal HIN and the driving signal LIN can be formed by the same PWM signal, and the PWM signal forms opposite signals through the NOT gate to prevent the first signal transfer module and the second signal transfer module from being input with a high level at the same time.

[0072] Figure 7 An implementation of a first current generating module is shown. The first current generating module may include a first current branch, a second current branch, a first bias current source (the current of the first bias current source is I SET ) and the third current branch, the first current branch includes MOS tube MP1, MOS tube NLD1 and MOS tube MN1, MOS tube NLD1 is a high-voltage MOS tube, and the capacitor C in the figure P1 The parasitic capacitance of NLD1, the second current branch includes MOS transistor MN2, and the third current branch includes MOS transistor MP2 and MOS transistor MP3. MOS transistor MN1 and MOS transistor MN2 form a current mirror, and MOS transistor MN2 is connected in parallel with the first bias current source and then connected in series with MOS transistor MP2. MOS transistor MP2 and MOS transistor MP3 form a current mirror.

[0073] The second current branch is used to replicate the current of the first current branch. The current of the third current branch is equal to the sum of the currents of the second current branch and the first bias current source, and the sum of the currents of the second current branch and the first bias current source is recorded as Itotal_H. The third current branch outputs Itotal_H, and Itotal_H is connected to the first end of the first capacitor module through the first signal transfer module.

[0074] Figure 8 An implementation of a second current generating module is shown. The second current generating module may include a fourth current branch, a fifth current branch, a second bias current source and a sixth current branch. The fourth current branch includes a MOS tube MP4, a MOS tube NLD2 and a MOS tube MN5. The MOS tube NLD2 is a high-voltage MOS tube. The capacitor C in the figure P2 The parasitic capacitance of NLD2 is connected, the fifth current branch includes MOS transistor MP5, MOS transistor MN3 and MOS transistor MN4, the second bias current source can be the same as the first bias current source, and the sixth current branch includes MOS transistor MP6 and MOS transistor MP7. MOS transistor MP4 and MOS transistor MP5 form a current mirror, MOS transistor MN3 and MOS transistor MN4 form a current mirror, MOS transistor MN4 and the second bias current source are connected in parallel and then connected in series with MOS transistor MP6. MOS transistor MP6 and MOS transistor MP7 form a current mirror.

[0075] The fifth current branch is used to copy the current of the fourth current branch. The current of the sixth current branch is equal to the sum of the currents of the fifth current branch and the second bias current source; the sum of the currents of the fifth current branch and the second bias current source is recorded as Itotal_L. The fourth current branch connects the connection point of the high-side power tube and the low-side power tube; the sixth current branch outputs Itotal_L, and Itotal_L is connected to the first end of the second capacitor module through the second signal transfer module.

[0076] like Fig. 9 , the first signal transfer module may include a first inverter INV1 and a second inverter INV2.

[0077] The input end of the first inverter INV1 receives the output signal of the AND gate AND1, which is equivalent to connecting the driving signal source of the high-side power tube. The power supply end of the first inverter is used to connect the power supply VDD, and the ground end of the first inverter is grounded.

[0078] The output end of the first inverter INV1 is connected to the input end of the second inverter INV2, the power end of the second inverter INV2 is connected to the current output end of the first current generating module; the ground end of the second inverter INV2 is grounded; the output end of the second inverter INV2 is connected to the first end of the first capacitor module C1.

[0079] like Fig. 9 The first threshold trigger module may include a third inverter INV3 and a fourth inverter INV4. The inverter has a threshold trigger characteristic.

[0080] The input end of the third inverter INV3 is the input end of the first threshold trigger module, connected to the first end of the first capacitor module C1; the power supply end of the third inverter INV3 is used to connect the power supply VDD; the ground end of the third inverter INV3 is grounded.

[0081] An output terminal of the third inverter INV3 is connected to an input terminal of the fourth inverter INV4.

[0082] The power supply end of the fourth inverter INV4 is connected to the power supply; the grounding end of the fourth inverter INV4 is grounded; the output end of the fourth inverter INV4 is the output end of the first threshold trigger module, which is used to connect the gate of the high-side power tube.

[0083] like Fig. 9 , the high side dead time principle is as follows:

[0084] Assuming that in the initial case, the driving signal HIN is at a low level and the driving signal LIN is at a high level, the first inverter INV1 outputs a high level. At this time, the low-side tube in the second inverter INV2 is turned on, providing a discharge path from the first capacitor module C1 to the ground. Therefore, the second inverter INV2 outputs a low level. After passing through the third inverter INV3 and the fourth inverter INV4, the final output signal DT_H is a low level, and the high-side power tube is in the off state. Similarly, the signal DT_L is a high level, and the low-side power tube will be in the on state. At this time, V SW is 0;

[0085] When the drive signal HIN becomes low and the drive signal LIN becomes high, the half-bridge conduction state switches to the low-side power tube being turned off and the high-side power tube being turned on. Due to the reverse freewheeling effect of the inductor in the half-bridge external load module, after the low-side power tube is turned off, the switch node voltage V SW Will quickly rise to the bus voltage V BUS , V SW Forming a positive dv / dt. Due to the bootstrap capacitor C Boot The existence of V SW The positive dv / dt formed on the high side is quickly coupled to the high side floating source VDDH, so the same magnitude of dv / dt is also formed on the high side floating source VDDH. Since the gate and source of MOS tube NLD1 are short-circuited, MOS tube NLD1 is in a normally closed state. When a positive dv / dt is formed on VDDH, due to the parasitic capacitance C of MOS tube NLD1 P1 The gate voltage of MOS tube MP1 lags behind the high-side floating source VDDH, which will generate a parasitic current I flowing through the drain-source end of MOS tube NLD1. P1 , the output current Itotal_H increases (Itotal_H=I P1 +I SET). Since the first inverter INV1 outputs a low level, the high-side tube in the second inverter INV2 is turned on, and the current Itotal_H charges the first capacitor module C1 through the high-side tube in the second inverter INV2. When the voltage across the first capacitor module C1 is charged to the threshold V th When the charging time is: Wherein C1 is the capacitance value of the first capacitor module C1, and the output level of the third inverter INV3 is reversed. The charging time is the high-side dead time.

[0086] When the external load changes, the switch node voltage V SW The dv / dt changes accordingly, the total detection current Itotal_H changes, and the charging time of the first capacitor module C1 also changes, realizing different sizes of dead time, thereby achieving the effect of high-side dead time adaptation.

[0087] like Fig.10 The connection structure of the fifth inverter INV5 and the sixth inverter INV6 of the second signal transfer module is the same as that of the first signal transfer module. The second threshold trigger module includes the seventh inverter INV7 and the eighth inverter INV8, and the connection structure is the same as that of the first threshold trigger module.

[0088] like Fig.10 , the low side dead time principle is as follows:

[0089] Assuming that in the initial case, the driving signal HIN is at a high level and the driving signal LIN is at a low level, the fifth inverter INV5 outputs a high level. At this time, the low-side tube in the sixth inverter INV6 is turned on, providing a discharge path from the second capacitor module C2 to the ground. Therefore, the sixth inverter INV6 outputs a low level. After passing through the seventh inverter INV7 and the eighth inverter INV8, the final output signal DT_L is a low level, and the high-side power tube is in the off state. Similarly, the signal DT_H is a high level, and the low-side power tube will be in the on state. At this time, V SW is the bus voltage V BUS ;

[0090] When the drive signal HIN becomes high and the drive signal LIN becomes low, the half-bridge conduction state switches to the high-side power tube being turned off and the low-side power tube being turned on. Due to the energy storage effect of the inductor in the half-bridge external load module, after the high-side power tube is turned off, the switch node voltage V SW will quickly drop to 0, V SW A negative dv / dt is formed. Since the gate and source of MOS tube NLD2 are short-circuited, MOS tube NLD2 is in a normally closed state. SW When a negative dv / dt is formed, due to the parasitic capacitance C of the MOS tube NLD2 P2Due to the existence of , the gate voltage change of MOS tube MN5 lags behind the switch node voltage V SW , a parasitic current I will flow through the drain-source end of MOS tube NLD2 P2 , the output current Itotal_L increases (Itotal_L=I P2 +I SET ). Since the fifth inverter INV5 outputs a low level, the high-side tube in the sixth inverter INV6 is turned on, and the current Itotal_L charges the second capacitor module C2 through the high-side tube in the sixth inverter INV6. When the voltage across the second capacitor module C2 is charged to the threshold value V of the seventh inverter INV7, th When the charging time is: Wherein C2 is the capacitance value of the second capacitor module C2, and the output level of the seventh inverter INV7 is reversed. The charging time is the low-side dead time.

[0091] When the external load changes, the switch node voltage V SW The dv / dt changes accordingly, the total detection current Itotal_L changes, and the charging time of the second capacitor module C2 also changes, realizing different sizes of dead time, thereby achieving the effect of low-side dead time adaptation.

[0092] Based on the above embodiments, the embodiments of the present application also provide a GaN driver chip, and the GaN driver chip includes any one of the above dead time circuits. The load module includes an inductor, for example, the load module includes a Buck circuit, and the Buck circuit includes an inductor. Among them, when the driving source signal of a power tube changes from indicating shutdown to indicating conduction, the current generating module charges the capacitor module, and the output signal of the threshold trigger module can be flipped only when the charging reaches the threshold trigger module. The output signal of the threshold trigger module is connected to the gate of the power tube, and the time to charge to the threshold is the dead time. When the driving signals of the high-side power tube and the low-side power tube are flipped, the inductor energy storage in the load module is used to make the current generating module generate current. When the inductance in the load module changes, the current generated by the current generating module changes, thereby changing the charging time and the dead time, that is, the dead time can change with the change of the inductance of the load module.

[0093] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. A person skilled in the art may understand and implement the present embodiment without creative effort.

[0094] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A dead time circuit, characterized in that: Applied to a power tube circuit, the power tube circuit comprises a bus, a high-side power tube and a low-side power tube, the bus, the high-side power tube, the low-side power tube and the ground are connected in sequence; the connection point between the high-side power tube and the low-side power tube is used to connect a load module; the load module comprises an inductor; The dead time circuit includes a bootstrap module, a first current generating module, a first signal transfer module, a first capacitor module and a first threshold triggering module; The first end of the bootstrap module is connected to the connection point of the high-side power tube and the low-side power tube, the second end of the bootstrap module is connected to the positive power supply end of the first current generating module, and the negative power supply end of the first current generating module is grounded; the current output end of the first current generating module is connected to the first end of the first capacitor module through the first signal transfer module, and the second end of the first capacitor module is grounded; The input end of the first signal transfer module is used to connect the driving signal source of the high-side power tube; The output end of the first signal transfer module is connected to the first end of the first capacitor module; The first end of the first capacitor module is connected to the input end of the first threshold trigger module; The output end of the first threshold trigger module is used to connect the gate of the high-side power tube; When the voltage at the first terminal of the bootstrap module increases, the voltage at the second terminal of the bootstrap module increases simultaneously; when the voltage at the second terminal of the bootstrap module increases, the current generated by the first current generating module increases; When the driving signal source of the high-side power tube sends a signal to turn on the high-side power tube, the first signal transfer module charges the first capacitor module with the current generated by the first current generating module; when the first capacitor module is charged to a voltage reaching a threshold of the first threshold trigger module, the output signal of the first threshold trigger module is flipped; When the driving signal source of the high-side power tube sends a signal to cut off the high-side power tube, the first signal relay module causes the first capacitor module to discharge to the ground; when the first capacitor module is discharged until the voltage reaches the threshold of the first threshold trigger module, the output signal of the first threshold trigger module is flipped.

2. The dead time circuit according to claim 1, wherein: The bootstrap module includes a bootstrap capacitor and a bootstrap diode; The anode of the bootstrap diode is used to connect to a power supply, and the power supply is used to supply power to the first current generating module, the first signal conversion module and the first threshold triggering module; The cathode of the bootstrap diode is connected to the first end of the bootstrap capacitor; The second end of the bootstrap capacitor is connected to the connection point of the high-side power tube and the low-side power tube; The first end of the bootstrap capacitor is the second end of the bootstrap module, and is connected to the power supply end of the first current generating module.

3. The dead time circuit according to claim 1, wherein: The first current generating module includes a first current branch, a second current branch, a first bias current source and a third current branch; The second current branch is used to replicate the current of the first current branch; The current of the third current branch is equal to the sum of the currents of the second current branch and the first bias current source; The first current branch is connected between the second end of the bootstrap module and ground; The third current branch provides a current output end of the first current generating module and is connected to the first end of the first capacitor module through the first signal transfer module.

4. The dead time circuit according to claim 1, wherein: The first signal transfer module includes a first inverter and a second inverter; The input end of the first inverter is the input end of the first signal transfer module, which is used to connect the driving signal source of the high-side power tube; the power supply end of the first inverter is used to connect the power supply, and the power supply is used to power the first current generating module, the first signal transfer module and the first threshold trigger module; the ground end of the first inverter is grounded; The output end of the first inverter is connected to the input end of the second inverter; The power supply end of the second inverter is connected to the current output end of the first current generating module; the grounding end of the second inverter is grounded; and the output end of the second inverter is connected to the first end of the first capacitor module.

5. The dead time circuit according to claim 1, wherein: The first threshold trigger module includes a third inverter and a fourth inverter; The input end of the third inverter is the input end of the first threshold trigger module, connected to the first end of the first capacitor module; the power supply end of the third inverter is used to connect to the power supply, and the power supply is used to power the first current generating module, the first signal converter module and the first threshold trigger module; the ground end of the third inverter is grounded; The output end of the third inverter is connected to the input end of the fourth inverter; The power supply end of the fourth inverter is connected to the power supply; The ground terminal of the fourth inverter is grounded; the output terminal of the fourth inverter is the output terminal of the first threshold trigger module, which is used to connect the gate of the high-side power tube.

6. A dead time circuit, characterized in that: Applied to a power tube circuit, the power tube circuit comprises a bus, a high-side power tube and a low-side power tube, the bus, the high-side power tube, the low-side power tube and the ground are connected in sequence; the connection point between the high-side power tube and the low-side power tube is used to connect a load module; the load module comprises an inductor; The dead time circuit includes a second current generating module, a second signal transfer module, a second capacitor module and a second threshold triggering module; The connection point of the high-side power tube and the low-side power tube is connected to the negative power supply end of the second current generating module, the positive power supply end of the second current generating module is connected to the power supply, the current output end of the second current generating module is connected to the first end of the second capacitor module through the second signal transfer module, and the second end of the second capacitor module is grounded; The input end of the second signal transfer module is used to connect the driving signal source of the low-side power tube; The output end of the second signal transfer module is connected to the first end of the second capacitor module; A first end of the second capacitor module is connected to an input end of the second threshold trigger module; The output end of the second threshold trigger module is used to connect the gate of the low-side power tube; When the voltage at the connection point between the high-side power tube and the low-side power tube decreases, the current generated by the second current generating module increases; When the driving signal source of the low-side power tube sends a signal to turn on the low-side power tube, the second signal transfer module charges the second capacitor module with the current generated by the second current generating module; when the second capacitor module is charged to a voltage reaching a threshold of the second threshold trigger module, the output signal of the second threshold trigger module is flipped; When the driving signal source of the low-side power tube sends a signal to cut off the low-side power tube, the second signal relay module causes the second capacitor module to discharge to the ground; when the second capacitor module is discharged until the voltage reaches the threshold of the second threshold trigger module, the output signal of the second threshold trigger module is flipped.

7. The dead time circuit according to claim 6, characterized in that: The second current generating module includes a fourth current branch, a fifth current branch, a second bias current source and a sixth current branch; The fifth current branch is used to replicate the current of the fourth current branch; The current of the sixth current branch is equal to the sum of the currents of the fifth current branch and the second bias current source; The fourth current branch is connected to the connection point of the high-side power tube and the low-side power tube; The sixth current branch provides a current output end of the second current generating module and is connected to the first end of the second capacitor module through the second signal transfer module.

8. The dead time circuit according to claim 6, wherein: The second signal transfer module includes a fifth inverter and a sixth inverter; The input end of the fifth inverter is the input end of the second signal transfer module, which is used to connect the driving signal source of the low-side power tube; the power supply end of the fifth inverter is used to connect the power supply, and the power supply is used to power the second current generating module, the second signal transfer module and the second threshold trigger module; the ground end of the fifth inverter is grounded; The output end of the fifth inverter is connected to the input end of the sixth inverter; The power supply end of the sixth inverter is connected to the current output end of the second current generating module; the grounding end of the sixth inverter is grounded; and the output end of the sixth inverter is connected to the first end of the second capacitor module.

9. The dead time circuit according to claim 6, characterized in that: The second threshold trigger module includes a seventh inverter and an eighth inverter; The input end of the seventh inverter is the input end of the second threshold trigger module, connected to the first end of the second capacitor module; the power supply end of the seventh inverter is used to connect to the power supply, and the power supply is used to power the second current generating module, the second signal transfer module and the second threshold trigger module; the ground end of the seventh inverter is grounded; The output end of the seventh inverter is connected to the input end of the eighth inverter; The power supply end of the eighth inverter is connected to the power supply; The grounding terminal of the eighth inverter is grounded; the output terminal of the eighth inverter is the output terminal of the second threshold trigger module, which is used to connect the gate of the low-side power tube.

10. A GaN driver chip, characterized in that: The GaN driver chip comprises the dead time circuit according to any one of claims 1 to 9.

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