Non-isolated resonant converter and driving circuit and driving method thereof

Abstract

This invention discloses a non-isolated resonant switching converter, comprising a transformer, a resonant slot, a first switching device coupled between an input node and the resonant slot, a second switching device coupled between the resonant slot and the secondary winding of the transformer, and a third switching device coupled between the secondary winding and a reference ground. The third switching device is driven by a first driver, the second switching device is driven by a second driver, and the first switching device is driven by the third driver. When the first and third switching devices are turned on, and the second switching device is turned off, a first capacitor used to power the second driver is charged. When the first and third switching devices are turned off, and the second switching device is turned on, the first capacitor charges a second capacitor used to power the third driver.

Description

Technical Field

[0001] Embodiments of the present invention relate to an electronic circuit, and more specifically, to a non-isolated switching converter and its driving circuit. Prior Technology

[0002] A switching converter is a circuit that converts input voltage to output voltage. A buck converter's output voltage is lower than its input voltage, while a boost converter's output voltage is higher than its input voltage. A resonant converter is a switching converter that uses a resonant tank circuit to convert a DC input voltage to a DC output voltage. In a resonant converter, a sampling transformer can be used to convert the voltage on its primary winding. A traditional resonant converter includes an inverter that converts the DC input voltage into a square wave. The resonant tank circuit filters out harmonics from the square wave, generating a sinusoidal current. This sinusoidal current is supplied to a rectifier via a transformer, and the rectifier's output is filtered by an output capacitor to produce a DC output voltage. Summary of the Invention

[0003] To address the driving problem of non-isolated switching converters, embodiments of the present invention disclose a non-isolated resonant converter, its driving circuit, and driving method.

[0004] According to an embodiment of the present invention, a non-isolated switching converter is provided, comprising: an input node for receiving an input voltage; an output node for providing an output voltage; a transformer including a primary winding and a secondary winding; a resonant slot including a resonant capacitor and a resonant inductor series coupled between a first resonant slot node and a second resonant slot node, wherein the resonant inductor is formed by the primary winding; a first switching device coupled between the input node and the first resonant slot node; a second switching device coupled between the first resonant slot node and the secondary winding; a third switching device coupled between the secondary winding and a reference ground; and a first driving integrated circuit including a first driver and a second driver, wherein the first driver provides a first driving signal according to a first control signal to drive the input node and the second resonant slot node. A third switching device, wherein the second driver provides a second driving signal to drive the second switching device according to a second control signal, the first driver is powered by a power supply, and the second driver is powered by the voltage across a first bootstrap capacitor; and a second driving integrated circuit, including a third driver, wherein the third driver provides a third driving signal to drive the first switching device according to a third control signal, and the third driver is powered by the voltage across a second bootstrap capacitor, wherein when the third switching device and the first switching device are turned on and the second switching device is turned off, the power supply charges the first bootstrap capacitor, and when the third switching device and the first switching device are turned off and the second switching device is turned on, the first bootstrap capacitor charges the second bootstrap capacitor.

[0005] According to an embodiment of the present invention, a driving circuit is also provided for driving a first switching device, a second switching device, and a third switching device connected in series between an input voltage and a reference ground, wherein the first switching device is coupled to the input voltage, the third switching device is coupled to the reference ground, and the second switching device is coupled between the first switching device and the third switching device. The driving circuit includes: a first driving integrated circuit, providing a first driving signal to drive the third switching device and providing a second driving signal to drive the second switching device. The first driving integrated circuit has a power supply pin coupled to a power source, a bootstrap pin, a first control input pin for receiving a first control signal, a second control input pin for receiving a second control signal, a first drive output pin for providing the first driving signal according to the first control signal, a second drive output pin for providing the second driving signal according to the second control signal, and a power supply pin coupled to the second power source. The first driving integrated circuit includes a switching pin at a common node of the first and second switching devices, wherein a first bootstrap capacitor is coupled between the bootstrap pin and the switching pin of the first driving integrated circuit; and a second driving integrated circuit that provides a third driving signal to drive the first switching device and a fourth driving signal, wherein the fourth driving signal and the first driving signal jointly drive the third switching device. The second driving integrated circuit has a power supply pin coupled to the power supply, a bootstrap pin, a first control input pin for receiving the first control signal, a second control input pin for receiving the third control signal, a first driving output pin for providing the fourth driving signal according to the first control signal, a third driving output pin for providing the third driving signal according to the third control signal, and a switching pin coupled to a common node of the first and second switching devices, wherein a second bootstrap capacitor is coupled between the bootstrap pin and the switching pin of the second driving integrated circuit.

[0006] According to an embodiment of the present invention, a driving method is also provided for driving a first switching device, a second switching device, and a third switching device connected in series between an input voltage and a reference ground, wherein the first switching device is coupled to the input voltage, the third switching device is coupled to the reference ground, and the second switching device is coupled between the first switching device and the third switching device. The driving method includes: receiving a first control signal and providing a first driving signal to drive the third switching device through a first driver; supplying power to the first driver through a power supply; receiving a second control signal and providing a second driving signal to drive the second switching device through a second driver; supplying power to the second driver through the voltage across a first bootstrap capacitor; receiving a third control signal and providing a third driving signal to drive the first switching device through a third driver; supplying power to the third driver through the voltage across a second bootstrap capacitor; charging the first bootstrap capacitor through the power supply when the third switching device and the first switching device are turned on and the second switching device is turned off; and charging the second bootstrap capacitor through the first bootstrap capacitor when the third switching device and the first switching device are turned off and the second switching device is turned on.

[0007] According to the present invention, the driving of multiple switching devices in a non-isolated switching converter is realized in a simple configuration without the need for multiple additional power supplies. Simple Explanation of the Diagram

[0008] To better understand this invention, it will be described in detail with reference to the following accompanying drawings. Identical or similar elements are represented by the same reference numerals. The following drawings are for illustrative purposes only and are not necessarily drawn to scale.

[0009] [Figure 1] shows a circuit diagram of a non-isolated resonant converter 100 according to an embodiment of the present invention;

[0010] [Figure 2] shows a circuit diagram of a non-isolated resonant converter 200 according to an embodiment of the present invention;

[0011] [Figure 3] shows a timing diagram 300 of the non-isolated resonant converter 200 shown in Figure 2 according to an embodiment of the present invention;

[0012] [Figure 4] shows a circuit diagram of the driving circuit 40 according to an embodiment of the present invention;

[0013] [Figure 5] shows a circuit diagram of the driving circuit 50 according to an embodiment of the present invention;

[0014] [Figure 6] shows a circuit diagram of a non-isolated resonant converter 600 according to an embodiment of the present invention;

[0015] [Figure 7] shows a flowchart of a driving method 700 according to an embodiment of the present invention. Implementation

[0016] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, materials, or methods have not been specifically described to avoid obscuring the invention.

[0017] Throughout this specification, references to "an embodiment," "an embodiment," "one embodiment," or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment or embodiment is included in at least one embodiment of the invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an embodiment," or "an embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment or embodiment. Furthermore, specific features, structures, or characteristics can be combined in any suitable combination and / or sub-combination in one or more embodiments or embodiments. Moreover, those skilled in the art will understand that the accompanying drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. The same reference numerals indicate the same elements. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0018] Figure 1 shows a circuit schematic of a non-isolated resonant converter 100 according to an embodiment of the present invention. The non-isolated resonant switching converter 100 has an input node 110 for receiving an input voltage Vin and an output node 120 for providing an output voltage Vo. The non-isolated resonant switching converter 100 includes a transformer having a primary winding W1 and a secondary winding W2, a resonant slot 10, switching devices Q1, Q2, and S1 connected in series between the input node 110 and a reference ground, and a drive circuit 20 for driving the switching devices Q1, Q2, and S1. The resonant slot 10 includes a resonant capacitor Cr and a resonant inductor Lr connected in series between resonant slot nodes 101 and 102. In one embodiment, the switching devices Q1, Q2, and S1 may include, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), a laterally diffused metal-oxide-semiconductor (LDMOS), and other suitable transistors.

[0019] The primary winding W1 can be simplified to a series connection of a magnetizing inductor Lm and a leakage inductance, with the leakage inductance serving as the resonant inductor Lr. In the embodiment shown in Figure 1, the resonant capacitor Cr has a first end coupled to a resonant slot node 101 and a second end coupled to one end of the resonant inductor Lr. The other end of the resonant inductor Lr is coupled to a resonant slot node 102 via the magnetizing inductor Lm. Those skilled in the art should also understand that the detailed circuit structure of the resonant slot 10 is not limited to the embodiment shown in Figure 1 and may include other suitable circuit structures.

[0020] Switching device Q1 is coupled between input node 110 and resonant slot node 101, switching device Q2 is coupled between resonant slot node 101 and secondary winding W2, and switching device S1 is coupled between secondary winding W2 and reference ground. In the embodiment shown in FIG1, secondary winding W2 has terminals 103, 104, and a center tap 105. In one embodiment, terminal 103 is coupled to a common node of switching devices Q2 and S1, and center tap 105 is coupled to output node 120 to provide output voltage Vo. In one embodiment, switching device S2 is coupled between terminal 104 and reference ground. Switching device S2 may include metal-oxide-semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), laterally diffused metal-oxide-semiconductor (LDMOS), and other suitable transistors. Those skilled in the art will understand that the connections of switching devices Q1, Q2, S1, S2, resonant slot 10, primary winding W1 and secondary winding W2 of transformer are not limited to the embodiment shown in FIG1, and may include other suitable connections.

[0021] The driving circuit 20 drives switching devices Q1, Q2, and S1 according to control signals PWMS1, PWMP1, and PWMP2. The driving circuit 20 includes drivers 11-13. In one embodiment, drivers 11 and 12 are integrated on a driving integrated circuit (IC) 21, and driver 13 is integrated on a driving integrated circuit 22. Driver 11 receives the control signal PWMS1 and provides a driving signal Vgs11 according to the control signal PWMS1. Driver 11 is powered by a power supply Vsup through a switch Dsp1. In one embodiment, switch Dsp1 is a diode, with its anode coupled to the power supply Vsup and its cathode coupled to driver 11. In another embodiment, switch Dsp1 is a field-effect transistor (FET). Driver 12 receives the control signal PWMP2 and provides a driving signal Vg2 according to the control signal PWMP2. Driver 12 is powered by the voltage Vbs1 across bootstrap capacitor Cbs1. The bootstrap capacitor Cbs1 can be located outside the driver integrated circuit 21 or integrated on the driver integrated circuit 21. In one embodiment, one end 106 of the bootstrap capacitor Cbs1 is coupled to the cathode of the diode Dsp1, and the other end 107 of the bootstrap capacitor Cbs1 is coupled to the common node of the switching device Q2 and the switching device S1. The driver 13 receives the control signal PWMP1 and provides the drive signal Vg1 according to the control signal PWMP1. The driver 13 is powered by the voltage Vbs2 across the bootstrap capacitor Cbs2. The bootstrap capacitor Cbs2 can be located outside the driver integrated circuit 22 or integrated on the driver integrated circuit 22. In one embodiment, one end 108 of the bootstrap capacitor Cbs2 is coupled to one end 106 of the bootstrap capacitor Cbs1 through the bootstrap diode Db1, and the other end 109 of the bootstrap capacitor Cbs2 is coupled to the common node of the switching device Q1 and the switching device Q2. The anode of bootstrap diode Db1 is coupled to one end 106 of bootstrap capacitor Cbs1, and the cathode of bootstrap diode Db1 is coupled to one end 108 of bootstrap capacitor Cbs2. Switching device S1 is driven by drive signal Vgs11, switching device Q2 is driven by drive signal Vg2, and switching device Q1 is driven by drive signal Vg1.

[0022] In one embodiment, when switching device S1 is turned on, power supply Vsup charges bootstrap capacitor Cbs1. For example, bootstrap capacitor Cbs1 is charged by current flowing through power supply Vsup, diode Dsp1, bootstrap capacitor Cbs1, switching device S1, and reference ground. In one embodiment, when switching device Q2 is turned on, bootstrap capacitor Cbs1 charges bootstrap capacitor Cbs2. For example, bootstrap capacitor Cbs2 is charged by current flowing from one end 106 of bootstrap capacitor Cbs1, bootstrap diode Db1, bootstrap capacitor Cbs2, and switching device Q2 to the other end 107 of bootstrap capacitor Cbs1. In one embodiment, switching devices S1 and Q1 are simultaneously turned on and off, and switching device Q2 is alternately turned on with switching devices S1 and Q1. Those skilled in the art will understand that there may be a delay between the turn-on of switching device Q1 and the turn-on of switching device S1, and there may also be a delay between the turn-off of switching device Q1 and the turn-off of switching device S1. In one embodiment, the maximum voltage of the drive signal Vgs11 is higher than the maximum voltage of the drive signal Vg2, and the maximum voltage of the drive signal Vg2 is higher than the maximum voltage of the drive signal Vg1.

[0023] In one embodiment, the switching device S1 may include multiple transistors coupled in parallel to handle large currents. The driving circuit 20 also includes a driver 14 integrated on the driving integrated circuit 22. The driver 14 receives a control signal PWMS1 and provides a driving signal Vgs12 according to the control signal PWMS1. The driver 14 is powered by a power supply Vsup through a switch Dsp2. In one embodiment, the switch Dsp2 is a diode, with its anode coupled to the power supply Vsup and its cathode coupled to the driver 14. The switching device S1 is driven by both driving signals Vgs11 and Vgs12. In one embodiment, the maximum voltage of the driving signal Vgs12 is higher than the maximum voltage of the driving signal Vg2. Embodiments of the invention may provide more than one driving signal to drive the switching device S1. In one embodiment, drivers 11-12 may be integrated on one integrated circuit, and drivers 13-14 may be integrated on another integrated circuit. In another embodiment, drivers 11-14 may be integrated on another integrated circuit.

[0024] Figure 2 shows a circuit diagram of a non-isolated resonant converter 200 according to an embodiment of the present invention. As shown in Figure 2, the non-isolated resonant switching converter 200 further includes switching devices Q3 and Q4. Switching device Q3 is coupled between the input node 110 and the resonant slot node 102, and switching device Q4 is coupled between the resonant slot node 102 and the secondary winding W2. In one embodiment, terminal 104 of the secondary winding W2 is coupled to a common node of switching devices Q4 and Q2. Switching devices Q3 and Q4 may include, for example, metal-oxide-semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), laterally diffused metal-oxide-semiconductor (LDMOS), and other suitable transistors.

[0025] The driving circuit 20 further includes drivers 15-17. In one embodiment, drivers 15-16 are integrated on the driving integrated circuit 23, and driver 17 is integrated on the driving integrated circuit 24. Driver 15 receives a control signal PWMS2 and provides a drive signal Vgs21 according to the control signal PWMS2. Driver 15 is powered by a power supply Vsup through a switch Dsp3. In one embodiment, the switch Dsp3 is a diode, with its anode coupled to the power supply Vsup and its cathode coupled to driver 15. Driver 16 receives a control signal PWMP1 and provides a drive signal Vg4 according to the control signal PWMP1. Driver 16 is powered by the voltage Vbs3 across the bootstrap capacitor Cbs3. The bootstrap capacitor Cbs3 may be located outside the driving integrated circuit 23 or may be integrated on the driving integrated circuit 23. In one embodiment, one end 301 of the bootstrap capacitor Cbs3 is coupled to the cathode of the diode Dsp3, and the other end 302 of the bootstrap capacitor Cbs3 is coupled to the common node of the switching device Q4 and the switching device S2. The driver 17 receives the control signal PWMP2 and provides the drive signal Vg3 according to the control signal PWMP2. The driver 17 is powered by the voltage Vbs4 across the bootstrap capacitor Cbs4. The bootstrap capacitor Cbs4 may be external to the driver integrated circuit 24 or may be integrated on the driver integrated circuit 24. In one embodiment, one end 303 of the bootstrap capacitor Cbs4 is coupled to the bootstrap diode Db2, and the other end 304 of the bootstrap capacitor Cbs4 is coupled to the common node of the switching device Q3 and the switching device Q4. The anode of the bootstrap diode Db2 is coupled to one end 301 of the bootstrap capacitor Cbs3, and the cathode of the bootstrap diode Db2 is coupled to one end 303 of the bootstrap capacitor Cbs4. The switching device S2 is driven by the drive signal Vgs21. Switching device Q4 is driven by drive signal Vg4 according to control signal PWMP1, so as to control switching device Q4 and switching device Q1 to be turned on and off simultaneously. Switching device Q3 is driven by drive signal Vg3 according to control signal PWMP2, so as to control switching device Q3 and switching device Q2 to be turned on and off simultaneously.

[0026] In one embodiment, when switching device S2 is turned on, the bootstrap capacitor Cbs3 is charged by the power supply Vsup. For example, the current flowing through the power supply Vsup, diode Db2, bootstrap capacitor Cbs3, switching device S2, and reference ground charges bootstrap capacitor Cbs2. In one embodiment, when switching device Q4 is turned on, bootstrap capacitor Cbs3 charges bootstrap capacitor Cbs4. For example, the current flowing from one end 301 of bootstrap capacitor Cbs3, bootstrap diode Db2, bootstrap capacitor Cbs4, and switching device Q4 to the other end 302 of bootstrap capacitor Cbs3 is used to charge bootstrap capacitor Cbs4. In one embodiment, switching devices S2 and Q3 are simultaneously turned on and off, and switching device Q4 is alternately turned on with switching devices S2 and Q3. Those skilled in the art will understand that there may be a delay between the turn-on of switching device Q3 and the turn-on of switching device S2, and there may be a delay between the turn-off of switching device Q3 and the turn-off of switching device S2. In one embodiment, the maximum voltage of drive signal Vgs21 is higher than the maximum voltage of drive signal Vg4, and the maximum voltage of drive signal Vg4 is higher than the maximum voltage of drive signal Vg3.

[0027] In one embodiment, the switching device S2 may include multiple transistors coupled in parallel to handle large currents. The driving circuit 20 also includes a driver 18 integrated on the driving integrated circuit 24. The driver 18 receives a control signal PWMS2 and provides a driving signal Vgs22 according to the control signal PWMS2. The driver 18 is powered by a power supply Vsup through a switch Dsp4. In one embodiment, the switch Dsp4 is a diode, with its anode coupled to the power supply Vsup and its cathode coupled to the driver 18. The switching device S2 is driven by driving signals Vgs21 and Vgs22. In one embodiment, the maximum voltage of the driving signal Vgs22 is higher than the maximum voltage of the driving signal Vg4. Embodiments of the present invention may provide more than one driving signal to drive the switching device S2. In one embodiment, drivers 15-16 may be integrated on one integrated circuit, and drivers 17-18 may be integrated on another integrated circuit. In another embodiment, drivers 15-18 may be integrated on one integrated circuit.

[0028] Figure 3 shows a timing diagram 300 of the non-isolated resonant converter 200 shown in Figure 2 according to an embodiment of the present invention. From top to bottom, timing diagram 300 shows control signal PWMP1, drive signal Vg4 (301) and drive signal Vg1 (dashed line 302), control signal PWMS1, drive signals Vgs11 and Vgs12, control signal PWMP2, drive signal Vg2 (303) and drive signal Vg3 (dashed line 304), control signal PWMS2, drive signals Vgs21 and Vgs22, voltage Vbs1 (305) across bootstrap capacitor Cbs1, voltage Vbs2 (dashed line 306) across bootstrap capacitor Cbs2, voltage Vbs3 (307) across bootstrap capacitor Cbs3, and voltage Vbs4 (dashed line 308) across bootstrap capacitor Cbs4.

[0029] Referring to Figure 3, when the control signal PWMP1 goes high, drive signals Vg1 and Vg4 turn on switching devices Q1 and Q4, respectively. When the control signal PWMS1 goes high, drive signals Vgs11 and Vgs12 turn on switching device S1. When the control signal PWMP2 goes high, drive signals Vg2 and Vg3 turn on switching devices Q2 and Q3, respectively. When the control signal PWMS2 goes high, drive signals Vgs21 and Vgs22 turn on switching device S2.

[0030] In one embodiment, when control signals PWMP1 and PWMS1 are at logic high level and control signals PWMP2 and PWMS2 are at logic low level, switching devices Q1, S1, and Q4 are turned on, and switching devices Q2, Q3, and S2 are turned off. Bootstrap capacitors Cbs1 and Cbs4 are charged, and voltages Vbs1 and Vbs4 increase. Bootstrap capacitors Cbs2 and Cbs3 are amplified, and voltages Vbs2 and Vbs3 decrease. In another embodiment, when control signals PWMP1 and PWMS1 are at logic low level and control signals PWMP2 and PWMS2 are at logic high level, switching devices Q1, S1, and Q4 are turned off, and switching devices Q2, Q3, and S2 are turned on. Bootstrap capacitors Cbs2 and Cbs3 are charged, and voltages Vbs2 and Vbs3 increase. Bootstrap capacitors Cbs1 and Cbs4 are discharged, and voltages Vbs1 and Vbs4 decrease.

[0031] In the embodiment shown in Figure 3, there is a delay time Td1 between the turn-on of switching devices Q1 and Q4 and the turn-on of switching device S1; a delay time Td2 between the turn-off of switching device S1 and the turn-off of switching devices Q1 and Q4; a delay time Td3 between the turn-on of switching devices Q2 and Q3 and the turn-on of switching device S2; a delay time Td4 between the turn-off of switching device S2 and the turn-off of switching devices Q2 and Q3; a delay time Td5 between the turn-off of switching devices Q1 and Q4 and the turn-on of switching devices Q2 and Q3; and a delay time Td6 between the turn-off of switching devices Q2 and Q3 and the turn-on of switching devices Q1 and Q4. In one embodiment, the maximum voltages of drive signals Vg4 and Vg2 are at the same level, the maximum voltages of drive signals Vg1 and Vg3 are at the same level, and the maximum voltages of drive signals Vgs11, Vgs12, Vgs21, and Vgs22 are at the same level, as shown in Figure 3. The maximum voltage of drive signal Vg1 is lower than the maximum voltage of drive signal Vg4. The maximum voltage of drive signal Vg4 is lower than the maximum voltage of drive signals Vgs11 and Vgs12. The maximum voltage of drive signal Vg3 is lower than the maximum voltage of drive signal Vg2. The maximum voltage of drive signal Vg2 is lower than the maximum voltage of drive signals Vgs21 and Vgs22.

[0032] Figure 4 shows a circuit diagram of a drive circuit 40 according to an embodiment of the present invention. The drive circuit 40 includes a drive integrated circuit 21A and a drive integrated circuit 22A for driving switching devices Q1, Q2 and S1, which are connected in series between the input voltage Vin and the reference ground as shown in Figure 2.

[0033] Each driver circuit 21A and 22A includes: a power supply pin VCC coupled to the power supply Vsup, a bootstrap pin BST, a control input pin PWMH, a control input pin PWML, a drive output pin HG, a drive output pin LG, a switch pin SW, and a reference ground pin GND coupled to a reference ground. Driver circuit 21A includes driver 11 and driver 12. Driver 11 is coupled to the control input pin PWML of driver circuit 21A to receive the control signal PWMS1, and coupled to the drive output pin LG of driver circuit 21A to provide the drive signal Vgs11. Driver 12 is coupled to the control input pin PWMH of driver circuit 21A to receive the control signal PWMP2, and coupled to the drive output pin HG of driver circuit 21A to provide the drive signal Vg2. Driver circuit 22A includes driver 13 and driver 14. Driver 13 is coupled to the control input pin PWMH of driver circuit 22A to receive the control signal PWMP1, and is coupled to the drive output pin HG of driver circuit 22A to provide the drive signal Vg1. Driver 14 is coupled to the control input pin PWML of driver circuit 22A to receive the control signal PWMS1, and is coupled to the drive output pin LG of driver circuit 22A to provide the drive signal Vgs12. Diode DSP1 is coupled between the power supply pin VCC and the bootstrap pin BST of driver circuit 21A. The anode of diode DSP1 is coupled to the power supply pin VCC of driver circuit 21A, and the cathode of diode DSP1 is coupled to the bootstrap pin BST of driver circuit 21A. Diode DSP2 is coupled between the power supply pin VCC and the bootstrap pin BST of driver circuit 22A. The anode of diode DSP2 is coupled to the power supply pin VCC of driver circuit 22A, and the cathode of diode DSP2 is coupled to the bootstrap pin BST of driver circuit 22A. The switching pin SW of driver circuit 21A is coupled to the common node of switching devices S1 and Q2. The switching pin SW of driver circuit 22A is coupled to the common node of switching devices Q1 and Q2.

[0034] Referring again to Figure 4, bootstrap capacitor Cbs1 is coupled between the bootstrap pin BST and the switch pin SW of driver circuit 21A, and bootstrap capacitor Cbs2 is coupled between the bootstrap pin BST and the switch pin SW of driver circuit 22A. The anode of bootstrap diode Db1 is coupled to the bootstrap pin BST of driver circuit 21A, and the cathode of bootstrap diode Db1 is coupled to the bootstrap pin BST of driver circuit 22A. When switching devices S1 and Q1 are on and switching device Q2 is off, bootstrap capacitor Cbs1 is charged by power supply Vsup through diode Dsp1 of driver circuit 21A; when switching device Q2 is on and switching devices S1 and Q1 are off, bootstrap capacitor Cbs1 charges bootstrap capacitor Cbs2 through bootstrap diode Db1. In one embodiment, bootstrap capacitor Csp1 is coupled between the power supply pin VCC of driver circuit 21A and reference ground, and bootstrap capacitor Csp2 is coupled between the power supply pin VCC of driver circuit 22A and reference ground. In one embodiment, the capacitance value of bootstrap capacitor Csp1 is greater than the capacitance value of bootstrap capacitor Cbs1, and the capacitance value of bootstrap capacitor Cbs1 is greater than the capacitance value of bootstrap capacitor Cbs2.

[0035] Figure 5 shows a circuit diagram of a drive circuit 50 according to an embodiment of the present invention. The drive circuit 50 includes a drive integrated circuit 23A and a drive integrated circuit 24A for driving switching devices Q3, Q4 and S2, which are connected in series between the input voltage Vin and the reference ground as shown in Figure 2.

[0036] Each driver circuit 23A and 24A includes: a power supply pin VCC coupled to the power supply Vsup, a bootstrap pin BST, a control input pin PWMH, a control input pin PWML, a drive output pin HG, a drive output pin LG, a switch pin SW, and a reference ground pin GND coupled to a reference ground. Driver circuit 23A includes drivers 15 and 16. Driver 15 is coupled to the control input pin PWML of driver circuit 23A to receive the control signal PWMS2, and coupled to the drive output pin LG of driver circuit 23A to provide the drive signal Vgs21. Driver 16 is coupled to the control input pin PWMH of driver circuit 23A to receive the control signal PWMP1, and coupled to the drive output pin HG of driver circuit 23A to provide the drive signal Vg4. Driver circuit 24A includes drivers 17 and 18. Driver 17 is coupled to the control input pin PWMH of driver circuit 24A to receive the control signal PWMP2, and is coupled to the drive output pin HG of driver circuit 24A to provide the drive signal Vg3. Driver 18 is coupled to the control input pin PWML of driver circuit 24A to receive the control signal PWMS2, and is coupled to the drive output pin LG of driver circuit 24A to provide the drive signal Vgs22. Diode DSP3 is coupled between the power supply pin VCC and the bootstrap pin BST of driver circuit 23A. The anode of diode DSP3 is coupled to the power supply pin VCC of driver circuit 23A, and the cathode of diode DSP3 is coupled to the bootstrap pin BST of driver circuit 23A. Diode DSP4 is coupled between the power supply pin VCC and the bootstrap pin BST of driver circuit 24A. The anode of diode DSP4 is coupled to the power supply pin VCC of driver circuit 24A, and the cathode of diode DSP4 is coupled to the bootstrap pin BST of driver circuit 24A. The switching pin SW of driver circuit 23A is coupled to the common node of switching devices S2 and Q4. The switching pin SW of driver circuit 24A is coupled to the common node of switching devices Q3 and Q4.

[0037] Referring again to Figure 5, bootstrap capacitor Cbs3 is coupled between the bootstrap pin BST and the switch pin SW of driver circuit 23A, and bootstrap capacitor Cbs4 is coupled between the bootstrap pin BST and the switch pin SW of driver circuit 24A. The anode of bootstrap diode Db2 is coupled to the bootstrap pin BST of driver circuit 23A, and the cathode of bootstrap diode Db2 is coupled to the bootstrap pin BST of driver circuit 24A. When switching devices S2 and Q3 are on and switching device Q4 is off, bootstrap capacitor Cbs3 is charged by power supply Vsup through diode Dsp3 of driver circuit 23A; when switching device Q4 is on and switching devices S2 and Q3 are off, bootstrap capacitor Cbs3 charges bootstrap capacitor Cbs4 through bootstrap diode Db2. In one embodiment, bootstrap capacitor Csp3 is coupled between the power supply pin VCC of driver circuit 23A and reference ground, and bootstrap capacitor Csp4 is coupled between the power supply pin VCC of driver circuit 24A and reference ground. In one embodiment, the capacitance value of bootstrap capacitor Csp3 is greater than the capacitance value of bootstrap capacitor Cbs3, and the capacitance value of bootstrap capacitor Cbs3 is greater than the capacitance value of bootstrap capacitor Cbs4.

[0038] Figure 6 shows a circuit diagram of a non-isolated resonant converter 600 according to an embodiment of the present invention. As shown in Figure 6, the resonant slot 10B includes a resonant capacitor Cr, a resonant inductor Lr1, and a resonant inductor Lr2 connected in series between resonant slot nodes 101 and 102. In one embodiment, the resonant inductor Lr1 is the leakage inductance of the primary winding W11, and the resonant inductor Lr2 is the leakage inductance of the primary winding W12. The non-isolated resonant switching converter 400 also includes drive integrated circuits 21A to 24A. Drive integrated circuits 21A to 22A drive switching devices Q1, Q2, and S1, and drive integrated circuits 23A to 24A drive switching devices Q3, Q4, and S2.

[0039] Figure 7 shows a flowchart of a driving method 700 according to an embodiment of the present invention. The driving method 700 is used to drive a first switching device, a second switching device, and a third switching device connected in series between an input voltage and a reference ground, wherein the first switching device is coupled to the input voltage, the third switching device is coupled to the reference ground, and the second switching device is coupled between the first and third switching devices. The driving method 700 includes steps S11 to S18.

[0040] In step S11, the first driver receives the first control signal and provides the first drive signal to drive the third switching device.

[0041] In step S12, the first driver is powered by a power supply.

[0042] In step S13, the second driver receives the second control signal and provides the second drive signal to drive the second switching device.

[0043] In step S14, the second driver is powered by the voltage across the first bootstrap capacitor.

[0044] In step S15, a third control signal is received and a third drive signal is provided by the third driver to drive the first switching device.

[0045] In step S16, the third driver is powered by the voltage across the second bootstrap capacitor.

[0046] In step S17, when the third switching device and the first switching device are turned on and the second switching device is turned off, the first bootstrap capacitor is charged by the power supply.

[0047] In step S18, when the third switching device and the first switching device are disconnected and the second switching device is turned on, the second bootstrap capacitor is charged through the first bootstrap capacitor. In one embodiment, the capacitance value of the first bootstrap capacitor is greater than the capacitance value of the second bootstrap capacitor. In one embodiment, the maximum voltage of the first drive signal is higher than the maximum voltage of the second drive signal, and the maximum voltage of the second drive signal is higher than the maximum voltage of the third drive signal. In one embodiment, the current flowing through the first bootstrap capacitor, the bootstrap diode, the second bootstrap capacitor, and the second switching device charges the second bootstrap capacitor.

[0048] In one embodiment, the driving method 700 further includes providing a fourth driving signal via a fourth driver according to a first control signal, the fourth driving signal and the first driving signal jointly driving a third switching device, and supplying power to the fourth driver via a power supply. In one embodiment, the maximum voltage of the fourth driving signal is higher than the maximum voltage of the second driving signal.

[0049] It should be noted that the execution order of the steps in the flowchart above is not limited to that shown in Figure 7. Two consecutive function blocks can be executed simultaneously or in reverse order.

[0050] Although the invention has been described with reference to several exemplary embodiments, it should be understood that the terminology used is illustrative and exemplary, not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

[0051] 10: Resonant groove 11: Driver 12: Drive 13: Driver 14: Driver 15: Driver 16: Driver 17: Drive 18: Driver 20, 40, 50: Drive circuit 21, 21A: Driver integrated circuit (IC) 22, 22A: Driver integrated circuit 23, 23A: Driver integrated circuit 24, 24A: Driver integrated circuit 100, 200, 600: Non-isolated resonant converters 101: Resonant slot node 102: Resonant slot node 103:Terminal 104:Terminal 105: Center tap 106: One end 107: The other end 108: One end 109: The other end 110: Input node 120: Output node 300: Timing Diagram 301: One end 302: The other end 303: One end 304: The other end Vin: Input voltage Vo: Output voltage Q1, Q2, Q3, Q4, S1, S2: Switching devices W1: Primary winding W2: Secondary winding Cr: Resonant capacitor Cbs1, Cbs2, Cbs3, Cbs4: Bootstrap capacitors Db1, Db2: Bootstrap diodes Lm: Magnetizing inductance Lr, Lr1, Lr2: Resonant inductors PWMS1, PWMS2, PWMP1, PWMP2: Control signals Vsup: Power supply Dsp1, Dsp2, Dsp3: Switches (Diodes) Vg1, Vg2, Vg3, Vg4, Vgs11, Vgs12, Vgs21, Vgs22: Drive signals Vbs1, Vbs2, Vbs3, Vbs4: Voltage Td1, Td2, Td3, Td4, Td5, Td6: Delay duration VCC: Power supply pin BST: Bootstrap pin LG, HG: Control output pins SW: Switch pin GND: Reference ground pin PWML, PWMH: Control input pins W11, W12: Primary windings 700: Driver Method S11~S18: Steps

Claims

1. A non-isolated switch converter, comprising: The input node is used to receive the input voltage. Output nodes are used to provide output voltage; A transformer consists of a primary winding and a secondary winding; A resonant slot includes a resonant capacitor and a resonant inductor connected in series between a first resonant slot node and a second resonant slot node, wherein the resonant inductor is formed by the primary winding; a first switching device is coupled between the input node and the first resonant slot node. A second switching device is coupled between the first resonant slot node and the secondary winding; A third switching device is coupled between the secondary winding and the reference ground; The first driving integrated circuit includes a first driver and a second driver. The first driver provides a first driving signal according to a first control signal to drive the third switching device, and the second driver provides a second driving signal according to a second control signal to drive the second switching device. The first driver is powered by a power supply, and the second driver is powered by the voltage across the first bootstrap capacitor. The second driving integrated circuit includes a third driver, which provides a third driving signal according to a third control signal to drive the first switching device. The third driver is powered by the voltage across the second bootstrap capacitor. When the third switching device and the first switching device are turned on and the second switching device is turned off, the power supply charges the first bootstrap capacitor. When the third switching device and the first switching device are turned off and the second switching device is turned on, the first bootstrap capacitor charges the second bootstrap capacitor.

2. The non-isolated switching converter as claimed in claim 1, wherein the second drive integrated circuit further comprises: A fourth driver receives the first control signal and provides a fourth drive signal according to the first control signal. The fourth driver is powered by the power supply, wherein the fourth drive signal and the first drive signal jointly drive the third switching device.

3. The non-isolated switch converter as claimed in claim 1, wherein the capacitance value of the first bootstrap capacitor is greater than the capacitance value of the second bootstrap capacitor.

4. The non-isolated switch converter as claimed in claim 1, wherein the maximum voltage of the first drive signal is higher than the maximum voltage of the second drive signal, and the maximum voltage of the second drive signal is higher than the maximum voltage of the third drive signal.

5. The non-isolated switching converter as claimed in claim 1, wherein the power supply charging the first bootstrap capacitor comprises: The first charging current flows from the power source through the first bootstrap capacitor and the third switching device to the reference ground.

6. The non-isolated switch converter as claimed in claim 1, wherein charging of the second bootstrap capacitor by the first bootstrap capacitor comprises: The second charging current flows from the first terminal of the first bootstrap capacitor through the bootstrap diode, the second bootstrap capacitor, and the second switching device into the second terminal of the first bootstrap capacitor.

7. The non-isolated switch converter as claimed in claim 1, further comprising: A fourth switching device is coupled between the input node and the second resonant slot node; The fifth switching device is coupled between the second resonant slot node and the secondary winding; A sixth switching device is coupled between the secondary winding and the reference ground; The third driving integrated circuit includes a fifth driver and a sixth driver. The fifth driver provides a fifth driving signal according to a fourth control signal to drive the sixth switching device. The sixth driver provides a sixth driving signal according to the third control signal to drive the fifth switching device, so that the fifth switching device and the first switching device are simultaneously turned on and off. The fifth driver is powered by the power supply, and the sixth driver is powered by the voltage across the third bootstrap capacitor. The system also includes a fourth driving integrated circuit, comprising a seventh driver and an eighth driver. The seventh driver provides a seventh driving signal according to the second control signal to drive the fourth switching device, such that the fourth switching device and the second switching device are simultaneously turned on and off. The eighth driver provides an eighth driving signal according to the fourth control signal. The seventh driver is powered by the voltage across the fourth bootstrap capacitor, and the eighth driver is powered by the power supply. The eighth driving signal and the fifth driving signal jointly drive the sixth switching device. When the sixth switching device and the fourth switching device are turned on and the fifth switching device is turned off, the power supply charges the third bootstrap capacitor. When the sixth switching device and the fourth switching device are turned off and the fifth switching device is turned on, the third bootstrap capacitor charges the fourth bootstrap capacitor.

8. The non-isolated switch converter as claimed in claim 7, wherein the secondary winding has a first end, a second end and a center tap, a common node of the second and third switching devices is coupled to the first end of the secondary winding, a common node of the fifth and sixth switching devices is coupled to the second end of the secondary winding, and the output node is coupled to the center tap of the secondary winding.

9. A driving circuit for driving a first switching device, a second switching device, and a third switching device connected in series between an input voltage and a reference ground, wherein the first switching device is coupled to the input voltage, the third switching device is coupled to the reference ground, and the second switching device is coupled between the first switching device and the third switching device, the driving circuit comprising: A first driving integrated circuit provides a first driving signal to drive the third switching device and a second driving signal to drive the second switching device. The first driving integrated circuit has a power supply pin coupled to a power source, a bootstrap pin, a first control input pin for receiving a first control signal, a second control input pin for receiving a second control signal, a first drive output pin for providing the first driving signal according to the first control signal, a second drive output pin for providing the second driving signal according to the second control signal, and a switch pin coupled to a common node of the second and third switching devices. A first bootstrap capacitor is coupled between the bootstrap pin and the switch pin of the first driving integrated circuit. A second driving integrated circuit... A third drive signal is provided to drive the first switching device, and a fourth drive signal is provided, the fourth drive signal and the first drive signal jointly driving the third switching device. The second drive integrated circuit has a power supply pin coupled to the power supply, a bootstrap pin, a first control input pin for receiving the first control signal, a second control input pin for receiving the third control signal, a first drive output pin for providing the fourth drive signal according to the first control signal, a third drive output pin for providing the third drive signal according to the third control signal, and a switch pin coupled to a common node of the first and second switching devices, wherein a second bootstrap capacitor is coupled between the bootstrap pin and the switch pin of the second drive integrated circuit.

10. The driving circuit of claim 9, wherein the first driving integrated circuit further comprises: A first driver provides a first drive signal according to the first control signal to drive the third switching device, and the first driver is powered by the power supply. And a second driver, which provides the second drive signal according to the second control signal to drive the second switching device, the second driver being powered by the voltage across the first bootstrap capacitor.

11. The driving circuit as claimed in claim 9, wherein the second driving integrated circuit further comprises: The third driver provides the third driving signal according to the third control signal to drive the first switching device, and the third driver is powered by the voltage across the second bootstrap capacitor; And a fourth driver, which provides the fourth drive signal according to the first control signal, the fourth driver being powered by the power supply.

12. The driving circuit of claim 9, wherein the bootstrap pin of the first driving integrated circuit is coupled to the bootstrap pin of the second driving integrated circuit via a diode, wherein the anode of the diode is coupled to the bootstrap pin of the first driving integrated circuit and the cathode of the diode is coupled to the bootstrap pin of the second driving integrated circuit.

13. The drive circuit as claimed in claim 9, wherein the power supply charges the first bootstrap capacitor when the third switching device and the first switching device are turned on and the second switching device is turned off.

14. The drive circuit as claimed in claim 9, wherein when the third switching device and the first switching device are turned off and the second switching device is turned on, the first bootstrap capacitor charges the second bootstrap capacitor.

15. The driving circuit of claim 9, wherein the maximum voltage of the first driving signal is higher than the maximum voltage of the second driving signal, and the maximum voltage of the second driving signal is higher than the maximum voltage of the third driving signal.

16. The driving circuit as claimed in claim 9, wherein the capacitance value of the first bootstrap capacitor is greater than the capacitance value of the second bootstrap capacitor.

17. A driving method for driving a first switching device, a second switching device, and a third switching device connected in series between an input voltage and a reference ground, wherein the first switching device is coupled to the input voltage, the third switching device is coupled to the reference ground, and the second switching device is coupled between the first switching device and the third switching device, the driving method comprising: The first driver receives a first control signal and provides a first drive signal to drive the third switching device. The first driver is powered by a power source; The system receives a second control signal and provides a second drive signal to drive the second switching device via a second driver; the second driver is powered by the voltage across the first bootstrap capacitor; the system receives a third control signal and provides a third drive signal to drive the first switching device via a third driver; the third driver is powered by the voltage across the second bootstrap capacitor; when the third switching device and the first switching device are turned on and the second switching device is turned off, the first bootstrap capacitor is charged by the power supply; and when the third switching device and the first switching device are turned off and the second switching device is turned on, the second bootstrap capacitor is charged by the first bootstrap capacitor.

18. The driving method as claimed in claim 17, wherein the capacitance value of the first bootstrap capacitor is greater than the capacitance value of the second bootstrap capacitor.

19. The driving method as described in claim 17, further comprising: A fourth driver provides a fourth driving signal based on the first control signal, and the fourth driving signal and the first driving signal together drive the third switching device. And the power supply provides power to the fourth driver.

20. The driving method as claimed in claim 17, wherein the maximum voltage of the first driving signal is higher than the maximum voltage of the second driving signal, and the maximum voltage of the second driving signal is higher than the maximum voltage of the third driving signal.

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