Power supply circuit and driving circuit

Abstract

The present invention relates to the technical field of electronics, and provides a power supply circuit and a drive circuit, the power supply circuit comprising: a first resistor, the first end of which is coupled to a power supply; the clamping circuit is coupled to the second end of the first resistor, and the clamping circuit is used for clamping the voltage of a common node between the first resistor and the clamping circuit to a first voltage value; the first transistor is provided with a first end, a second end and a control end, the first end of the first transistor is coupled to a power supply, the control end of the first transistor is coupled to the common node, the second end of the first transistor serves as the output end of the power supply circuit, and the output end of the power supply circuit is used for providing a power supply voltage signal; and the linear voltage regulator is coupled between the power supply and the output end of the power supply circuit and is used for stabilizing the power supply voltage signal at a preset voltage value. The power supply circuit can quickly provide power supply voltage for the interior of the integrated circuit, and prevents the integrated circuit from being damaged or burnt due to control errors.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a power supply circuit and a drive circuit. Background Art

[0002] In the field of integrated circuits, it is often necessary to quickly establish an internal power supply and provide a power supply voltage to the integrated circuit system in time to quickly establish the relevant control loop. For example, in the scenario of fast power-on, the design of the gate driver faces special challenges. Due to the parasitic capacitance of the power switch tube, when the power is quickly powered on, the gate voltage may increase abnormally due to capacitive coupling. In this case, if the internal power supply is not established in time, the power switch tube may not be turned off in time, and the power switch tube may be turned on by mistake, causing the chip to be damaged or burned. Summary of the invention

[0003] The object of the present invention is to provide a power supply circuit and a driving circuit to solve the above-mentioned problems.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a power supply circuit, which includes: a first resistor, a first end of the first resistor is coupled to a power supply; a clamping circuit, the clamping circuit is coupled to the second end of the first resistor, and the clamping circuit is used to clamp the voltage of a common node between the first resistor and the clamping circuit to a first voltage value; a first transistor, having a first end, a second end and a control end, the first end of the first transistor is coupled to the power supply, the control end of the first transistor is coupled to the common node, the second end of the first transistor serves as an output end of the power supply circuit, and the output end of the power supply circuit is used to provide a power supply voltage signal; a linear voltage regulator is coupled between the power supply and the output end of the power supply circuit, and is used to stabilize the power supply voltage signal at a preset voltage value.

[0005] An embodiment of the present invention also provides a driving circuit, which is used to drive the high-side power switch tube and the low-side power switch tube in the switching converter. The driving circuit includes: an upper driving module, which is used to provide a high-side driving signal to drive the high-side power switch tube to be turned on and off; a lower driving module, which is used to provide a low-side driving signal to drive the low-side power switch tube to be turned on and off; and a power supply circuit of any of the above items, wherein the power supply circuit is used to supply power to the lower driving module.

[0006] Through the above technical solution, the clamping circuit is coupled to the power supply through the first resistor, and the clamping circuit is used to clamp the voltage of the common node between the first resistor and the clamping circuit to a first voltage value. The first end of the first transistor is coupled to the power supply, the control end of the first transistor is coupled to the common node, and the second end of the first transistor is used as the output end of the power supply circuit, and the output end of the power supply circuit is used to provide a power supply voltage signal; the linear voltage regulator is coupled between the power supply and the output end of the power supply circuit, and is used to stabilize the power supply voltage signal at a preset voltage value. The fast path formed by the clamping circuit, the first resistor, and the first transistor quickly pulls up the gate voltage of the first transistor in the case of fast power-on, ensures that the power supply voltage signal is quickly provided from the output end of the power supply circuit, realizes the rapid establishment of the internal power supply, and then quickly turns off the power switch tube. At the same time, the linear voltage regulator is a slow path, which is used to take over the fast path, stabilize the power supply voltage signal at a preset voltage value, thereby providing a continuous and stable power supply voltage signal, and then realizes the continuous shutdown of the power switch tube. The power supply circuit quickly provides the power supply voltage inside the integrated circuit to prevent the chip in the integrated circuit from being damaged or burned due to control errors.

[0007] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 is a schematic diagram of a half-bridge gate driving circuit according to an exemplary embodiment.

[0009] Figure 2 is a schematic diagram of a power supply circuit according to an exemplary embodiment.

[0010] Figure 3 is a schematic diagram of another power supply circuit according to an exemplary embodiment.

[0011] Figure 4 is a schematic diagram of another power supply circuit according to an exemplary embodiment.

[0012] Figure 5 is a schematic diagram of another power supply circuit according to an exemplary embodiment.

[0013] Figure 6 is a schematic diagram of another power supply circuit according to an exemplary embodiment.

[0014] Description of Reference Numerals cgd1-gate-drain capacitance of the high-side power switch tube, cgd2-gate-drain capacitance of the low-side power switch tube, Vm-power supply, HS-high-side power switch tube, LS-low-side power switch tube, DRV1-high-side drive signal, DRV2-low-side drive signal, A-common node, R1-first resistor, R2-first voltage-dividing resistor, R3-second voltage-dividing resistor, R4-second resistor, MN1-first transistor, MN2-second transistor, VCC-power supply voltage signal, PWM-switch control signal, M1-first drive tube, M2-second drive tube, C1-first capacitor, EA-error amplifier, Vref-reference voltage signal, JFET-junction field effect transistor, 10-power supply circuit, 21-feedback circuit, FB-feedback signal. DETAILED DESCRIPTION

[0015] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0016] In the description below, words such as “first” and “second” are only used for the purpose of distinguishing the description and should not be understood as indicating or implying relative importance or order.

[0017] In the field of power electronics, the performance of the gate driver is critical to the stability and efficiency of the entire system. In particular, in the scenario of fast power-on, the design of the gate driver faces special challenges. Due to the parasitic capacitance of the power switch tube, when the power is quickly powered on, the gate voltage may increase abnormally due to capacitive coupling. In this case, if the internal power supply is not established in time, the power switch tube may not be turned off in time, and the power switch tube may be turned on by mistake, causing the chip to be damaged or burned.

[0018] Figure 1 is a schematic diagram of a driving circuit according to an exemplary embodiment. Figure 1 The driving circuit is used to drive the high-side power switch tube HS and the low-side power switch tube LS in the switching converter. The driving circuit includes an upper driving module, a lower driving module and a power supply circuit 10.

[0019] The upper driving module is used to provide a high-side driving signal DRV1 to drive the high-side power switch tube HS to turn on and off. The lower driving module is used to provide a low-side driving signal DRV2 to drive the low-side power switch tube LS to turn on and off. The power supply circuit 10 is used to supply power to the lower driving module.

[0020] In a possible implementation, the lower driving module includes a plurality of driving tube groups. Figure 1In the illustrated embodiment, only one driving tube group is illustrated, including a first driving tube M1 and a second driving tube M2. The first driving tube M1 has a first end, a second end and a control end, the first end of the first driving tube M1 is used to receive a power supply voltage signal VCC, and the control end of the first driving tube M1 is used to receive a switch control signal PWM. The second driving tube M2 has a first end, a second end and a control end, the first end of the second driving tube M2 is coupled to the second end of the first driving tube M1 and provides a low-side driving signal DRV2, the second end of the second driving tube M2 is connected to a reference ground, and the control end of the second driving tube M2 is used to receive a switch control signal PWM.

[0021] The switch control signal PWM is used to control the on time and off time of the first drive tube M1 and the second drive tube M2. In the startup phase, the switch control signal PWM is logic high, the first drive tube M1 is turned off, the second drive tube M2 is turned on, and the control end of the low-side power switch tube LS is pulled low, thereby maintaining the off state.

[0022] When the power supply Vm is powered on quickly, the power supply Vm will couple the gate voltage of the high-side power switch tube HS through the gate-drain capacitor cgd1 of the high-side power switch tube, thereby turning on the high-side power switch tube HS and raising the SW node voltage. When the SW node voltage rises rapidly, it will couple the gate voltage of the low-side power switch tube LS through the gate-drain capacitor cgd2 of the low-side power switch tube, thereby turning on the low-side power switch tube LS. In the prior art, the power supply circuit for powering the lower drive module includes a feedback loop, and it takes a certain amount of time for the loop to establish the power supply voltage signal VCC, so that the low-side power switch tube LS cannot be quickly turned off by pulling down the drive tube in the lower drive module, resulting in the risk of the high-side power switch tube HS and the low-side power switch tube LS being turned on at the same time when the power supply Vm is powered on quickly.

[0023] In order to suppress the occurrence of this phenomenon, the present invention Figure 1 The power supply circuit 10 proposed in the illustrated embodiment can be used to quickly establish the power supply voltage signal VCC of the lower driving module when the power source Vm is quickly powered on, thereby realizing the rapid shutdown of the low-side power switch tube LS.

[0024] See also Figure 2 , Figure 2 FIG. 1 is a schematic diagram of a power supply circuit 10 according to an exemplary embodiment. Figure 2 As shown, the power supply circuit 10 may include a first resistor R1, a clamping circuit, a first transistor MN1 and a linear voltage regulator.

[0025] The first end of the first resistor R1 is coupled to the power source Vm. The clamp circuit is coupled to the second end of the first resistor R1. The clamp circuit is coupled to the power source Vm through the first resistor R1. The clamp circuit is used to clamp the voltage of the common node A between the first resistor R1 and the clamp circuit to a first voltage value.

[0026] The first transistor MN1 has a first end, a second end and a control end. The first end of the first transistor MN1 is coupled to the power supply Vm, the control end of the first transistor MN1 is coupled to the common node A, and the second end of the first transistor MN1 serves as the output end of the power supply circuit. The output end of the power supply circuit is used to provide a power supply voltage signal VCC.

[0027] The first transistor MN1 may be, but is not limited to, a suitable semiconductor device such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), an Insulated Gate Bipolar Transistor (IGBT), or a Bipolar Junction Transistor (BJT).

[0028] exist Figure 2 In the illustrated embodiment, the first transistor MN1 is illustrated as an N-type MOSFET tube. Specifically, the first transistor MN1 has a drain, a source and a gate, the drain of the first transistor MN1 is coupled to the power supply Vm, the gate of the first transistor MN1 is coupled to the common node A, and the source of the first transistor MN1 serves as the output end of the power supply circuit to provide a power supply voltage signal VCC.

[0029] The linear voltage regulator is coupled between the power source Vm and the output terminal of the power supply circuit, and is used for stabilizing the power supply voltage signal VCC at a preset voltage value.

[0030] The linear voltage regulator compares the supply voltage signal VCC at its output end with a preset voltage signal through a negative feedback loop, and the generated error signal is used to control the transistor in the linear voltage regulator, thereby stabilizing the supply voltage signal VCC at the preset voltage value required inside the integrated circuit. In one embodiment, the preset voltage value is set to be greater than the first voltage value of VA minus the turn-on threshold value VTH of the first transistor MN1, that is, the difference between the first voltage value and the preset voltage value is less than the turn-on threshold value VTH of the first transistor MN1.

[0031] The working principle of the power supply circuit is as follows: The clamp circuit, the first resistor R1, and the first transistor MN1 form a fast path, and the linear voltage regulator is a slow path. In the case of fast power-on, the power supply Vm makes the common node A reach the voltage value provided by the power supply Vm through the first resistor R1, that is, the voltage at the control end of the first transistor MN1 reaches the voltage value provided by the power supply Vm so that the first transistor MN1 can be turned on quickly, and then the power supply voltage signal VCC is provided at the output end of the power supply circuit 10 for other circuits (such as Figure 1 The first transistor MN1 is powered by the lower driving module in the embodiment shown. Subsequently, after being clamped by the clamping circuit, the voltage VA of the common node A is clamped at the first voltage value. When the voltage difference between the control terminal and the second terminal of the first transistor MN1 is greater than or equal to the conduction threshold value VTH of the first transistor MN1, the first transistor MN1 is always kept in the on state, and the supply voltage signal VCC provided by the second terminal of the first transistor MN1 is equal to VA-VTH. At the same time, the feedback loop of the linear voltage regulator will synchronously maintain the regulation of the supply voltage signal VCC. Since the final preset voltage value of the set supply voltage signal VCC is greater than VA-VTH, as the value of the supply voltage signal VCC on the second terminal of the first transistor MN1 continues to rise, when the voltage difference between the control terminal and the second terminal of the first transistor MN1 is less than the conduction threshold value VTH of the first transistor MN1, the first transistor MN1 is turned off, that is, the fast path is turned off. After the first transistor MN1 is turned off, the value of the supply voltage signal VCC is completely regulated by the linear voltage regulator, that is, the slow path continues to work, and finally the supply voltage signal VCC is stabilized at the preset voltage value.

[0032] exist Figure 2 In the illustrated embodiment, a fast path formed by the clamping circuit, the first resistor R1, and the first transistor MN1 quickly turns on the first transistor MN1 in the case of fast power-on to ensure the rapid establishment of the power supply voltage signal VCC as the internal power supply. At the same time, the linear voltage regulator is a slow path for stabilizing the power supply voltage signal VCC at a preset voltage value required by the integrated circuit after the fast path is disconnected.

[0033] Due to the influence of parasitic capacitance on the line, in order to further quickly turn on the first transistor MN1, in a possible implementation manner, refer to Figure 3 The power supply circuit may also include a first capacitor C1.

[0034] The first capacitor C1 is connected in parallel with the first resistor R1. In the case of fast power-on, the voltage of the common node A is quickly pulled to the voltage provided by the power source Vm through the first capacitor C1, thereby quickly turning on the first transistor MN1 to output the supply voltage signal VCC at its second terminal.

[0035] In one possible implementation, see Figure 4, the power supply circuit may further include a junction field effect transistor JFET.

[0036] The junction field effect transistor JFET has a first terminal, a second terminal and a control terminal. The first terminal of the junction field effect transistor JFET is coupled to the power source Vm, the second terminal of the junction field effect transistor JFET is coupled to the first terminal of the first resistor R1, and the control terminal of the junction field effect transistor JFET is connected to the reference ground.

[0037] The junction field effect transistor JFET is in a normally-on state. When the voltage difference between the second terminal of the junction field effect transistor JFET and the control terminal is greater than or equal to the pinch-off threshold of the junction field effect transistor JFET, the junction field effect transistor JFET is turned off.

[0038] In the case of fast power-on, the power source Vm sequentially passes through the junction field effect transistor JFET and the first resistor R1 to pull the voltage of the common node A to the voltage provided by the power source Vm, thereby quickly turning on the first transistor MN1. The JFET will then be pinched off, and the voltage on the second end of the JFET will remain at its pinch-off voltage. Since the pinch-off voltage of the JFET is less than the power supply voltage, a first resistor R1 with a smaller resistance value can be selected, which is beneficial to saving the area of ​​the integrated circuit. Figure 4 The working principle of the embodiment shown can be found in Figure 2 The working principle of the illustrated embodiment will not be described in detail here in order not to obscure the key points of the invention.

[0039] In one possible implementation, see Figure 5 , the power supply circuit can also be Figure 4 The embodiment shown further includes a first capacitor C1. The first capacitor C1 is connected in parallel with the first resistor R1.

[0040] In the case of fast power-on, the voltage of the common node A is quickly pulled to the voltage provided by the power supply Vm through the junction field effect transistor JFET and the first capacitor C1, thereby causing the first transistor MN1 to be quickly turned on to output the power supply voltage signal VCC at its second terminal. The JFET will then be pinched off, and the voltage on the second terminal of the JFET will remain at its pinch-off voltage. Since the pinch-off voltage of the JFET is less than the power supply voltage Vm, a first resistor R1 with a smaller resistance value and a first capacitor C1 with a smaller capacitance value can be selected, which is beneficial to saving the area of ​​the integrated circuit.

[0041] In one possible implementation, see Figure 6 The linear voltage regulator includes a feedback circuit 21, a second transistor MN2 and an error amplifier EA.

[0042] The feedback circuit 21 is coupled to the output terminal of the power supply circuit to receive the power supply voltage signal VCC and generate a feedback signal FB representing the power supply voltage signal VCC.

[0043] In a possible implementation, the feedback circuit 21 may include a first voltage-dividing resistor R2 and a second voltage-dividing resistor R3. The first voltage-dividing resistor R2 and the second voltage-dividing resistor R3 are coupled in series between the output end of the power supply circuit 10 and the reference ground. The first end of the first voltage-dividing resistor R2 is coupled to the output end of the power supply circuit 10, the second end of the first voltage-dividing resistor R2 is coupled to the first end of the second voltage-dividing resistor R3, the second end of the second voltage-dividing resistor R3 is grounded, and the voltage at the common node of the first voltage-dividing resistor R2 and the second voltage-dividing resistor R3 is the feedback signal FB. In one embodiment, the power supply voltage signal VCC is K times the feedback signal FB, that is, VCC=K×FB, where K is a constant greater than or equal to 1. The calculation formula of the proportionality coefficient K is as follows: K = (r2 + r3) / r3; Wherein, r2 represents the resistance value of the first voltage-dividing resistor R2, and r3 represents the resistance value of the second voltage-dividing resistor R3.

[0044] The second transistor MN2 has a first terminal, a second terminal and a control terminal. The first terminal of the second transistor MN2 is coupled to the power supply Vm, the second terminal of the second transistor MN2 is coupled to the output terminal of the power supply circuit 10, and the control terminal of the second transistor MN2 receives the error amplification signal. The second transistor MN2 can be, but is not limited to, a suitable semiconductor device such as MOSFET, IGBT, BJT, etc.

[0045] exist Figure 6 In the illustrated embodiment, the second transistor MN2 is illustrated as an N-type MOSFET tube. Specifically, the second transistor MN2 has a drain, a source and a gate, the drain of the second transistor MN2 is coupled to the power supply Vm, the gate of the second transistor MN2 is coupled to the output end of the error amplifier EA, and the source of the second transistor MN2 is coupled to the output end of the power supply circuit.

[0046] The error amplifier EA has a first input terminal, a second input terminal and an output terminal. The first input terminal of the error amplifier EA receives a reference voltage signal Vref, and the second input terminal of the error amplifier EA receives a feedback signal FB. The error amplifier EA amplifies the difference between the reference voltage signal Vref and the feedback signal FB and outputs an error amplified signal. In a possible implementation, the preset voltage value of the power supply voltage signal VCC is also K times the reference voltage signal Vref. Therefore, the difference between the first voltage value on the node A and the K times reference voltage signal Vref value is less than the conduction threshold of the first transistor MN1.

[0047] In a possible implementation, the linear voltage regulator may further include a reference signal providing circuit for providing a reference voltage signal Vref. The reference signal providing circuit has an input terminal and an output terminal, the input terminal of the reference signal providing circuit is coupled to the output terminal of the power supply circuit to receive the power supply voltage signal VCC, and the output terminal of the reference signal providing circuit is coupled to the first input terminal of the error amplifier EA.

[0048] In other embodiments, the reference signal providing circuit may also be used to generate a bias current for the error amplifier EA.

[0049] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0050] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0051] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A power supply circuit, characterized in that: The power supply circuit comprises: a first resistor, wherein a first end of the first resistor is coupled to a power source; a clamping circuit, the clamping circuit being coupled to the second end of the first resistor, the clamping circuit being configured to clamp a voltage at a common node between the first resistor and the clamping circuit to a first voltage value; A first transistor having a first end, a second end and a control end, wherein the first end of the first transistor is coupled to the power supply, the control end of the first transistor is coupled to the common node, the second end of the first transistor serves as an output end of the power supply circuit, and the output end of the power supply circuit is used to provide a power supply voltage signal; A linear voltage regulator is coupled between the power supply and the output terminal of the power supply circuit, and is used to stabilize the power supply voltage signal at a preset voltage value.

2. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes a first capacitor; The first capacitor is connected in parallel with the first resistor.

3. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes a junction field effect transistor; The junction field effect transistor has a first end, a second end and a control end. The first end of the junction field effect transistor is coupled to the power supply, the second end of the junction field effect transistor is coupled to the first end of the first resistor, and the control end of the junction field effect transistor is connected to the reference ground.

4. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes a first capacitor and a junction field effect transistor; The first capacitor is connected in parallel with the first resistor; The junction field effect transistor has a first end, a second end and a control end. The first end of the junction field effect transistor is coupled to the power supply, the second end of the junction field effect transistor is coupled to the first end of the first resistor, and the control end of the junction field effect transistor is connected to the reference ground.

5. The power supply circuit according to claim 1, characterized in that: The linear voltage regulator comprises: a feedback circuit coupled to the output terminal of the power supply circuit to receive the power supply voltage signal and generate a feedback signal representing the power supply voltage signal; A second transistor having a first end, a second end and a control end, the first end of the second transistor being coupled to the power supply, the second end of the second transistor being coupled to the output end of the power supply circuit, and the control end of the second transistor receiving the error amplification signal; The error amplifier has a first input terminal, a second input terminal and an output terminal. The first input terminal of the error amplifier receives a reference voltage signal, the second input terminal of the error amplifier receives the feedback signal, and the error amplifier amplifies the difference between the reference voltage signal and the feedback signal and outputs the error amplified signal.

6. The power supply circuit according to claim 5, characterized in that: The linear voltage regulator further comprises: A reference signal providing circuit is provided, wherein the reference signal providing circuit has an input terminal and an output terminal, wherein the input terminal of the reference signal providing circuit is coupled to the output terminal of the power supply circuit, and the output terminal of the reference signal providing circuit is coupled to the first input terminal of the error amplifier.

7. The power supply circuit according to claim 5, characterized in that: The supply voltage signal is K times the feedback signal, and a difference between the first voltage value and the K times reference voltage signal value is less than a turn-on threshold of the first transistor, where K is a constant greater than or equal to 1.

8. The power supply circuit according to claim 5, characterized in that: The feedback circuit comprises: A first voltage dividing resistor; A second voltage-dividing resistor, wherein the first voltage-dividing resistor and the second voltage-dividing resistor are coupled in series between the output end of the power supply circuit and a reference ground.

9. A driving circuit, characterized in that: The driving circuit is used to drive a high-side power switch tube and a low-side power switch tube in a switching converter, and the driving circuit includes: The upper driving module is used to provide a high-side driving signal to drive the high-side power switch tube to turn on and off; A lower driving module, used for providing a low-side driving signal to drive the low-side power switch tube to turn on and off; The power supply circuit according to any one of claims 1 to 8, wherein the power supply circuit is used to supply power to the lower driving module.

10. The driving circuit according to claim 9, characterized in that: The lower driving module also includes a driving pipe group; The driving tube set includes a first driving tube and a second driving tube; The first driving tube has a first end, a second end and a control end, the first end of the first driving tube is used to receive the power supply voltage signal, and the control end of the first driving tube is used to receive a switch control signal; The second driving tube has a first end, a second end and a control end. The first end of the second driving tube is coupled to the second end of the first driving tube and provides the low-side driving signal. The second end of the second driving tube is connected to the reference ground. The control end of the second driving tube is used to receive the switch control signal.

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