Gate drive circuit, drive method of switching device, and integrated circuit having switching device

Abstract

The application discloses a gate driving circuit and a driving method of a switching device and an integrated circuit with the switching device. In the active period of a high-side switch signal, a second voltage signal is provided to a high-side driving circuit to generate a driving signal to drive the high-side switch in a first time stage, and a first voltage signal is provided to the high-side driving circuit to generate the driving signal to drive the high-side switch in a second time stage. A first power voltage is used to charge a first capacitor to obtain the first voltage signal, the first capacitor is connected to a switching node of the high-side switch and a low-side switch, and the second voltage signal is obtained according to the power terminal voltage of the high-side switch. The application provides charges to the high-side driving circuit through different voltages, so that the capacity and volume of the capacitor can be reduced, and the cost can be reduced and the integration can be facilitated.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to a gate drive circuit, a drive method, and an integrated circuit having a switching device. Background Technology

[0002] A bridge switching circuit includes a high-side switch and a low-side switch connected together. One end of the high-side switch is connected to the input voltage, and one end of the low-side switch is connected to the reference ground potential. During the conduction of the low-side switch, the voltage at the switching node between the two switches is pulled down to the reference ground potential, while during the conduction of the high-side switch, the voltage at the switching node is gradually pulled up to the input voltage.

[0003] When the high-side switch is a MOS transistor, as the voltage at the switching node is gradually pulled up, the gate drive circuit of the high-side switch needs to generate a suitable drive voltage to meet the turn-on voltage requirements and thus control the switching state of the high-side switch. Based on the aforementioned voltage changes at the switching node, a relatively large drive voltage is required for the high-side switch to ensure it is fully turned on during the switching cycle. Current technology typically uses an external bootstrap capacitor with a large capacitance to provide sufficient drive voltage to the high-side switch, which increases cost and reduces system integration. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a gate driving circuit, driving method and integrated circuit having a switching device for solving the technical problems of high cost and low integration of the switching device driving circuit in the prior art.

[0005] The technical solution of the present invention is to provide a gate driving circuit for a switching device, the switching device including a high-side switching transistor and a low-side switching transistor connected together, wherein the input voltage is converted into an output voltage by switching the high-side switching transistor and the low-side switching transistor, and the gate driving circuit includes:

[0006] A first voltage circuit connects the switching nodes of the high-side switch and the low-side switch via a first capacitor. The first capacitor receives a first power supply voltage, which charges the first capacitor to obtain a first voltage signal. A voltage conversion circuit receives a second power supply voltage and obtains a second voltage signal based on the second power supply voltage, which is obtained through the loop node of the switching device. A high-side drive circuit is connected to the voltage conversion circuit and receives the output signal of the voltage conversion circuit to generate a drive signal to drive the high-side switch. The voltage conversion circuit receives the switching signal of the high-side switch and the first voltage signal. During the effective period of the switching signal of the high-side switch, in a first time phase, the voltage conversion circuit outputs the second voltage signal, and in a second time phase, the voltage conversion circuit outputs the first voltage signal.

[0007] Preferably, during the second time phase, the first voltage signal is greater than the second voltage signal.

[0008] Preferably, during the first time phase, the high-side driving circuit drives the high-side switch from an off state to a partially on state, and during the second time phase, the high-side driving circuit drives the high-side switch from a partially on state to a fully on state.

[0009] Preferably, the first power supply voltage is the input voltage, the output voltage, or the first power terminal voltage of the high-side switch, and the second power terminal of the high-side switch is connected to the low-side switch.

[0010] Preferably, the second power supply voltage is the input voltage or the first power terminal voltage of the high-side switch, or the input voltage or the first power terminal voltage of the high-side switch after conversion, wherein the second power terminal of the high-side switch is connected to the low-side switch.

[0011] Preferably, the voltage conversion circuit includes a first switching circuit and a second switching circuit; the input terminal of the first switching circuit receives the second power supply voltage, and when the first switching circuit is turned on, the signal at the output terminal of the first switching circuit serves as the second voltage signal; the input terminal of the second switching circuit receives the first voltage signal, and when the second switching circuit is turned on, the second switching circuit transmits the first voltage signal to the output terminal for output.

[0012] Preferably, the voltage conversion circuit includes a first control circuit, which receives the switching signal of the high-side switching transistor. When the switching signal becomes valid, the first control circuit controls the first switching circuit to turn on and controls the second switching circuit to turn off. When the on-time of the first switching circuit reaches the first time interval, the first control circuit controls the first switching circuit to turn off and controls the second switching circuit to turn on.

[0013] Preferably, the first control circuit uses a timer to generate the time of the first time period. When the switch signal becomes valid, the timer starts counting. When the count reaches a preset time, the timer outputs a trigger signal. The first control circuit controls the first switch circuit to disconnect and controls the second switch circuit to turn on according to the trigger signal.

[0014] Preferably, the first control circuit receives the switching signal. When the switching signal becomes valid, the first time period begins. The first control circuit includes a comparator. The comparator compares the voltage at the control terminal of the high-side switch transistor or the voltage at the switching node with the voltage at the first power terminal of the high-side switch transistor. When the difference between the two reaches a preset threshold, the comparator outputs a trigger signal, and the first time period ends. The first control circuit controls the first switching circuit to disconnect and controls the second switching circuit to turn on according to the trigger signal.

[0015] Preferably, the first switching circuit includes a first switching transistor, the first power terminal of the first switching transistor receives the second power supply voltage, and when the first switching transistor is turned on, the first switching transistor outputs the second power supply voltage to the output terminal as a first voltage signal output, and the second power terminal of the first switching transistor serves as the output terminal.

[0016] Preferably, the first switching circuit includes a first diode, the anode of the first diode receiving the second power supply voltage, and the cathode connected to the first power terminal of the first switching transistor.

[0017] In a second aspect, an integrated circuit with a switching device is provided, including the gate driving circuit described above, wherein the first capacitor and the high-side switching transistor are integrated in an integrated chip.

[0018] In a second aspect, a gate driving method for a switching device is provided, the switching device including a high-side switch and a low-side switch connected together, wherein an input voltage is converted into an output voltage by switching the high-side switch and the low-side switch, comprising:

[0019] The switching nodes of the high-side switch and the low-side switch are connected through one end of a first capacitor, and the other end of the first capacitor receives a first power supply voltage. The first power supply voltage charges the first capacitor to obtain a first voltage signal. The input voltage is received, and a second power supply voltage is received. A second voltage signal is obtained based on the second power supply voltage, which is obtained according to the loop node of the switching device. During the effective period of the switching signal of the high-side switch, in a first time phase, the voltage conversion circuit outputs the second voltage signal, and in a second time phase, the voltage conversion circuit outputs the first voltage signal. The first voltage signal or the second voltage signal is received to generate a drive signal to drive the high-side switch.

[0020] Preferably, the second voltage signal is obtained by converting the input voltage or the second voltage signal is equal to the magnitude of the input voltage; the second voltage signal is obtained by converting the first power terminal voltage of the high-side switch or the second voltage signal is equal to the magnitude of the first power terminal voltage of the high-side switch, wherein the second power terminal of the high-side switch is connected to the low-side switch.

[0021] Preferably, during the first time phase, the high-side driving circuit drives the high-side switch from an off state to a partially on state, and during the second time phase, the high-side driving circuit drives the high-side switch from a partially on state to a fully on state.

[0022] Preferably, the first power supply voltage is the input voltage, the output voltage, or the first power terminal voltage of the high-side switch, and the second power terminal of the high-side switch is connected to the low-side switch.

[0023] The circuit structure of this invention, during the effective period of the switching signal of the high-side switching transistor, supplies power to the high-side driving circuit with a second voltage signal in the first time period and with a first voltage signal in the second time period. The first voltage signal is obtained by charging the capacitor, and the second voltage signal is obtained by the input voltage. This invention can significantly reduce the capacitance and size of the capacitor, thereby reducing the cost of the driving circuit for the switching device. Furthermore, it allows the capacitor and the switching device to be integrated into a single chip, improving the system's integration level. Attached Figure Description

[0024] Figure 1 A circuit block diagram of the gate drive circuit of the switching device according to the present invention;

[0025] Figure 2 This is a detailed implementation diagram of the gate drive circuit of the switching device according to the present invention;

[0026] Figure 3 This is a detailed implementation diagram of the voltage conversion circuit according to the present invention;

[0027] Figure 4 This is a detailed implementation diagram of the charging control circuit according to the present invention. Detailed Implementation

[0028] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the present invention.

[0029] To provide the public with a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the invention, but those skilled in the art can fully understand the invention without these details.

[0030] The invention is described in more detail below by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0031] refer to Figure 1 A circuit block diagram of the gate drive circuit of the switching device according to the present invention and Figure 2 The diagram shows a specific implementation of the gate drive circuit of the switching device according to the present invention. The switching device of the present invention includes a high-side switch M1 and a low-side switch M2 connected together. The input voltage Vin is converted into an output voltage Vout by switching the high-side switch and the low-side switch. Here, the high-side switch and the low-side switch form a bridge switching circuit. The circuit system also includes an inductor and a capacitor. The input voltage Vin is a DC voltage signal, and the output voltage Vout is a DC voltage signal supplied to the load.

[0032] refer to Figure 2The gate driving circuit includes a first voltage circuit, a voltage conversion circuit, and a high-side driving circuit. Specifically, the first voltage circuit connects the switching nodes SW of the high-side switch and the low-side switch via a first capacitor Cboot. One end of the first capacitor Cboot is connected to the switching node SW, and the other end receives a first power supply voltage VT. The first power supply voltage charges the first capacitor to obtain a first voltage signal BST. The voltage conversion circuit receives a second power supply voltage and obtains a second voltage signal V2 based on the second power supply voltage, which is obtained through the loop node of the switching device. The high-side driving circuit is connected to the voltage conversion circuit and receives the output signal of the voltage conversion circuit to generate a driving signal to drive the high-side switch. The voltage conversion circuit receives the switching signal PWM2 of the high-side switch and the first voltage signal BST. During the effective period of the switching signal of the high-side switch, in a first time phase, the voltage conversion circuit outputs the second voltage signal V2, and in a second time phase, the voltage conversion circuit outputs the first voltage signal BST. In the second time phase, the second voltage signal V2 is less than the first voltage signal BST. The first power supply voltage is the input voltage or the output voltage. As those skilled in the art will know, the first power supply voltage can also be the input voltage or the output voltage converted voltage. The second power supply voltage is the input voltage or the first power terminal voltage of the high-side switch, or the input voltage or the first power terminal voltage of the high-side switch converted voltage.

[0033] In one example, the switching signal PWM2 of the high-side switch and the switching signal PWM1 of the low-side switch are obtained by other circuits in the switching control circuit. This can be obtained by a feedback circuit and a comparator circuit in the prior art based on the inductor current and the output feedback signal, which will not be specifically described in this application. In this example, the time period corresponding to the effective period of the high-side switch signal includes a first time phase and a second time phase, with the first time phase preceding the second time phase. In one example, during the first time phase, the high-side drive circuit drives the high-side switch from an off state to a partially on state; during the second time phase, the high-side drive circuit drives the high-side switch from a partially on state to a fully on state.

[0034] In the first time phase, the parasitic capacitance of the high-side switch is charged by the second voltage signal V2. In the second time phase, the parasitic capacitance of the high-side switch is charged by the first voltage signal. The second voltage signal V2 is obtained through the power circuit, which utilizes the circuit's power and greatly saves the capacity of the first capacitor. The capacity of the first capacitor is determined by the characteristics of the high-side switch. When the charging charge required by the parasitic capacitance is small, the capacity of the first capacitor is very small and can be integrated with the high-side switch on a single chip.

[0035] refer to Figure 2 and Figure 3 The circuit diagram shown illustrates a voltage conversion circuit comprising a first switching circuit and a second switching circuit. The input terminal of the first switching circuit receives the second power supply voltage. When the first switching circuit is turned on, the signal at the output terminal of the first switching circuit serves as the second voltage signal V2. The input terminal of the second switching circuit receives the first voltage signal BST. When the second switching circuit is turned on, the second switching circuit transmits the first voltage signal to its output terminal. In one example, the second switching circuit includes a second switching transistor S2. One power terminal of the second switching transistor S2 receives the first voltage signal BST, and the second power terminal is connected to the output terminal of the voltage conversion circuit.

[0036] In one example, the first switching circuit includes a first switching transistor S1. The first power terminal of the first switching transistor receives the second power supply voltage. When the first switching transistor is turned on, it outputs the second power supply voltage to its output terminal as a second voltage signal. The second power terminal of the first switching transistor serves as the output terminal. Those skilled in the art will understand that the second voltage signal can also be obtained by converting the input voltage through a circuit such as a switching circuit or an LDO. Further, the first switching circuit includes a first diode. The anode of the first diode receives the second power supply voltage, and the cathode is connected to the first power terminal of the first switching transistor. The first diode is used to prevent the high voltage of the BST from returning to the first power terminal of the first switching transistor.

[0037] In one example, the voltage conversion circuit includes a first control circuit that receives a switching signal from the high-side switch. When the switching signal becomes valid, the first control circuit controls the first switch circuit to turn on and controls the second switch circuit to turn off. When the on-time of the first switch circuit reaches the first time interval, the first control circuit controls the first switch circuit to turn off and controls the second switch circuit to turn on.

[0038] Specifically, in one example, the first control circuit uses a timer to generate the time of the first time period. When the switch signal becomes valid, the timer starts counting. When the count reaches a preset time, the timer outputs a trigger signal. The first control circuit controls the first switch circuit to disconnect and controls the second switch circuit to turn on according to the trigger signal.

[0039] Specifically, in another example, the first control circuit receives the switching signal. When the switching signal becomes valid, the first time period begins. The first control circuit includes a comparator that compares the voltage at the control terminal of the high-side switch transistor or the voltage at the switching node with the voltage at the first power terminal of the high-side switch transistor. When the difference between the two reaches a preset threshold, the comparator outputs a trigger signal, and the first time period ends. The first control circuit controls the first switching circuit to disconnect and controls the second switching circuit to turn on according to the trigger signal.

[0040] refer to Figure 4 This is one implementation where the first power supply voltage charges the first capacitor to obtain the first voltage signal BST. One end of the first capacitor Cboot is connected to the switch node SW, and the other end is connected to one end of capacitor C0 through a diode. The charging control circuit controls the charging voltage of capacitor Cboot. The first power supply voltage is the input voltage Vin. When the switch is on, the current generated by the first power supply voltage through the voltage divider resistor charges capacitor C0. The error amplifier receives the node voltage of the voltage divider resistor as the feedback voltage VFB and the reference voltage VREF to stabilize the voltage of capacitor C0 at a value corresponding to the reference voltage, thereby obtaining a stable DC voltage BST.

[0041] Furthermore, this invention also discloses an integrated circuit with a switching device, including the aforementioned gate driving circuit, wherein the first capacitor and the high-side switching transistor are integrated into a single integrated chip. In some switching devices, since the Miller platform requires relatively little charge, the second voltage signal provides most of the Miller charge in the first time phase. Thus, in the second time phase, the first capacitor requires less charge, resulting in a smaller capacitance value and a smaller capacitor size, which can be integrated into the chip, improving the system's integration density. The capacitor integrated into the chip can also be fabricated using power device methods, making implementation easier.

[0042] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A gate drive circuit for a switching device, the switching device comprising a high-side switch and a low-side switch connected together, wherein an input voltage is converted into an output voltage by switching the high-side switch and the low-side switch, characterized in that, The gate driving circuit includes: A first voltage circuit connects the switching nodes of the high-side switch and the low-side switch through a first capacitor. The first capacitor receives a first power supply voltage, and the first power supply voltage charges the first capacitor to obtain a first voltage signal. The voltage conversion circuit receives a second power supply voltage and obtains a second voltage signal based on the second power supply voltage, wherein the second power supply voltage is obtained through the loop node of the switching device; A high-side drive circuit is connected to the voltage conversion circuit and receives the output signal of the voltage conversion circuit to generate a drive signal to drive the high-side switching transistor. The voltage conversion circuit receives the switching signal of the high-side switch and the first voltage signal. During the effective period of the switching signal of the high-side switch, in a first time phase, the voltage conversion circuit outputs the second voltage signal, and in a second time phase, the voltage conversion circuit outputs the first voltage signal.

2. The gate driving circuit according to claim 1, characterized in that, During the second time phase, the first voltage signal is greater than the second voltage signal.

3. The gate driving circuit according to claim 1, characterized in that, During the first time phase, the high-side driving circuit drives the high-side switch from an off state to a partially on state. During the second time phase, the high-side driving circuit drives the high-side switch from a partially on state to a fully on state.

4. The gate driving circuit according to claim 1, characterized in that, The first power supply voltage is the input voltage, the output voltage, or the first power terminal voltage of the high-side switch transistor, and the second power terminal of the high-side switch transistor is connected to the low-side switch transistor.

5. The gate driving circuit according to claim 1, characterized in that, The second power supply voltage is the input voltage or the first power terminal voltage of the high-side switch, or the input voltage or the first power terminal voltage of the high-side switch after conversion. The second power terminal of the high-side switch is connected to the low-side switch.

6. The gate driving circuit according to claim 1, characterized in that, The voltage conversion circuit includes a first switching circuit and a second switching circuit. The input terminal of the first switching circuit receives the second power supply voltage. When the first switching circuit is turned on, the signal at the output terminal of the first switching circuit serves as the second voltage signal. The input terminal of the second switching circuit receives the first voltage signal. When the second switching circuit is turned on, the second switching circuit transmits the first voltage signal to the output terminal for output.

7. The gate driving circuit according to claim 6, characterized in that, The voltage conversion circuit includes a first control circuit. The first control circuit receives the switching signal of the high-side switching transistor. When the switching signal becomes valid, the first control circuit controls the first switching circuit to turn on and controls the second switching circuit to turn off. When the conduction time of the first switching circuit reaches the first time period, the first control circuit controls the first switching circuit to turn off and controls the second switching circuit to turn on.

8. The gate driving circuit according to claim 7, characterized in that, The first control circuit uses a timer to generate the duration of the first time period. When the switch signal becomes valid, the timer starts counting. When the countdown reaches a preset time, the timer outputs a trigger signal. The first control circuit controls the first switch circuit to disconnect and the second switch circuit to turn on according to the trigger signal.

9. The gate driving circuit according to claim 7, characterized in that, The first control circuit receives the switch signal, and the first time period begins when the switch signal becomes valid. The first control circuit includes a comparator, which compares the voltage at the control terminal of the high-side switch or the voltage at the switching node with the voltage at the first power terminal of the high-side switch. When the difference between the two reaches a preset threshold, the comparator outputs a trigger signal, the first time period ends, and the first control circuit controls the first switching circuit to disconnect and the second switching circuit to turn on according to the trigger signal.

10. The gate driving circuit according to claim 6, characterized in that, The first switching circuit includes a first switching transistor. The first power terminal of the first switch receives the second power supply voltage. When the first switch is turned on, the first switch outputs the second power supply voltage to the output terminal as the second voltage signal output, and the second power terminal of the first switch serves as the output terminal.

11. The gate driving circuit according to claim 10, characterized in that, The first switching circuit includes a first diode. The anode of the first diode receives the second power supply voltage, and the cathode is connected to the first power terminal of the first switching transistor.

12. An integrated circuit having a switching device, comprising the gate drive circuit according to any one of claims 1-11, The first capacitor and the high-side switch are integrated into a single chip.

13. A gate driving method for a switching device, the switching device comprising a high-side switch and a low-side switch connected together, wherein an input voltage is converted into an output voltage by switching the high-side switch and the low-side switch, characterized in that, include: One end of the first capacitor is connected to the switching nodes of the high-side switch and the low-side switch, and the other end of the first capacitor receives a first power supply voltage. The first power supply voltage charges the first capacitor to obtain a first voltage signal. Receive a second power supply voltage and obtain a second voltage signal based on the second power supply voltage, wherein the second power supply voltage is obtained according to the loop node of the switching device; During the active period of the switching signal of the high-side switch, in the first time phase, the voltage conversion circuit outputs the second voltage signal, and in the second time phase, the voltage conversion circuit outputs the first voltage signal. The first voltage signal or the second voltage signal is received to generate a drive signal to drive the high-side switching transistor.

14. The gate driving method according to claim 13, characterized in that, The second voltage signal is obtained by converting the first power terminal voltage of the high-side switch transistor, or the second voltage signal is equal to the magnitude of the first power terminal voltage of the high-side switch transistor, wherein the second power terminal of the high-side switch transistor is connected to the low-side switch transistor.

15. The gate driving method according to claim 13, characterized in that, In the first time phase, the high-side driving circuit drives the high-side switch from an off state to a partially on state. In the second time phase, the high-side driving circuit drives the high-side switch from a partially on state to a fully on state.

16. The gate driving method according to claim 13, characterized in that, The first power supply voltage is the input voltage, the output voltage, or the first power terminal voltage of the high-side switch. The second power supply voltage is the input voltage, the first power terminal voltage of the high-side switch, or the input voltage or the first power terminal voltage of the high-side switch after conversion. The second power terminal of the high-side switch is connected to the low-side switch.

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