Switch control circuit, power conversion circuit and switch control chip

Abstract

The invention discloses a switch control circuit, a power conversion circuit and a switch control chip. The switch control circuit comprises a power supply end, a power grounding end, a voltage sampling end, a switch tube and a grid control circuit, the power supply end and the power supply grounding end are respectively used for being electrically connected with a controlled power supply conversion module; the drain of the switch tube is connected with the power supply end, the source of the switch tube is connected with the power grounding end, and the grid of the switch tube is connected with the output end of the grid control circuit; the input end of the grid control circuit is connected with the voltage sampling end and used for controlling the switching-on and switching-off speed of the switching tube and restraining the voltage peak of the power supply end. According to the invention, the grid control circuit is used for controlling the switching-on and switching-off speed of the switching tube, so that the voltage peak of the power supply end of the power supply can be effectively reduced, the voltage stress borne by the switching tube is reduced, the service life of the switching tube is prolonged, and the normal work of the circuit is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of power conversion, and in particular to a switch control circuit, a power conversion circuit and a switch control chip. Background Art

[0002] In modern electronic technology, inductive switching DCDC circuits are widely used in various power management systems due to their high-efficiency energy conversion characteristics. However, at the moment when the switch is turned on and off, due to the influence of factors such as parasitic inductance and capacitance in the circuit, a significant voltage spike will be generated at the switch node. This voltage spike brings many problems. First, it will cause the switching device to be subjected to excessive voltage stress, increase the risk of damage to the switching device, and reduce the reliability and service life of the circuit. Secondly, the voltage spike will also cause electromagnetic interference (EMI) problems, have adverse effects on surrounding electronic equipment, and may cause system performance degradation or even failure.

[0003] In existing technical solutions, simple passive filtering circuits are usually used to try to mitigate voltage spikes. For example, capacitors are added at the switch nodes to absorb the spike energy, but this method often has limited effect and increases the loss and volume of the circuit. In addition, some traditional control strategies also have shortcomings when dealing with voltage spikes. They may not be able to accurately control the timing and speed of switch switching, resulting in poor spike suppression. Moreover, existing technologies often find it difficult to maintain stable spike suppression performance when facing complex load changes and working environments, thereby affecting the working stability and reliability of the entire circuit. Summary of the invention

[0004] The purpose of the present invention is to provide a switch control circuit, a power conversion circuit and a switch control chip to solve the problem that significant voltage spikes are easily generated at the switch nodes of the DCDC circuit, and the spike suppression effect of the existing method is poor, thereby affecting the working stability and reliability of the entire circuit.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is to provide a switch control circuit, which includes a power supply end, a power ground end, a voltage sampling end, a switch tube and a gate control circuit; the power supply end and the power ground end are respectively used to be electrically connected to a controlled power conversion module; the drain of the switch tube is connected to the power supply end, the source of the switch tube is connected to the power ground end, and the gate of the switch tube is connected to the output end of the gate control circuit; the input end of the gate control circuit is connected to the voltage sampling end, which is used to control the speed of closing and opening the switch tube and suppress the voltage spike at the power supply end.

[0006] In some embodiments, the gate control circuit includes an operational amplifier, a controller, a drive control unit and a drive adjustment circuit; the operational amplifier is used to output an op amp output voltage based on a reference voltage and a sampling voltage; wherein the reference voltage is generated by a reference voltage source, and the sampling voltage is obtained by sampling the voltage sampling end; the controller and the drive control unit are respectively used to receive the op amp output voltage, the drive control unit includes a first comparator, and the drive adjustment circuit includes a first drive circuit and a second drive circuit, the first comparator is used to compare the input op amp output voltage with a first reference voltage, and control the second drive circuit together with the controller; the controller is also used to control the first drive circuit.

[0007] In some embodiments, the first driving circuit includes a first PMOS tube and a first NMOS tube; the gates of the first PMOS tube and the first NMOS tube are respectively connected to the output ends corresponding to the controller, the source of the first PMOS tube is connected to the driving power supply, the drain of the first PMOS tube is connected to the drain of the first NMOS tube, and the source of the first NMOS tube is grounded.

[0008] In some embodiments, the second driving circuit includes a second PMOS tube, a third PMOS tube, a second NMOS tube and a third NMOS tube; the gates of the second PMOS tube and the second NMOS tube are respectively connected to the in-phase output terminal and the inverting output terminal of the first comparator, the gates of the third PMOS tube and the third NMOS tube are respectively connected to the corresponding output terminals of the controller, the source of the second PMOS tube is connected to the driving power supply, the drain of the second PMOS tube is connected to the source of the third PMOS tube, the drain of the third PMOS tube is connected to the drain of the second NMOS tube, the source of the second NMOS tube is connected to the drain of the third NMOS tube, and the source of the third NMOS tube is grounded.

[0009] In some embodiments, the drive control unit also includes a second comparator, and the drive regulation circuit also includes a third drive circuit. The second comparator is used to compare the input op amp output voltage with a second reference voltage, and control the third drive circuit together with the controller.

[0010] In some embodiments, the third driving circuit includes a fourth PMOS tube, a fifth PMOS tube, a fourth NMOS tube and a fifth NMOS tube; the gates of the fourth PMOS tube and the fourth NMOS tube are respectively connected to the in-phase output terminal and the inverting output terminal of the second comparator, the gates of the fifth PMOS tube and the fifth NMOS tube are respectively connected to the output terminals corresponding to the controller, the source of the fourth PMOS tube is connected to the driving power supply, the drain of the fourth PMOS tube is connected to the source of the fifth PMOS tube, the drain of the fifth PMOS tube is connected to the drain of the fourth NMOS tube, the source of the fourth NMOS tube is connected to the drain of the fifth NMOS tube, and the source of the fifth NMOS tube is grounded.

[0011] The present invention also provides a power conversion circuit, characterized in that the circuit includes a power conversion module and the above-mentioned switch control circuit, the power conversion module is used to connect to a first DC power supply, and convert the first DC power supply into a second DC power supply output under the action of the switch control circuit.

[0012] In some embodiments, the power conversion module includes an inductor, a diode and an output capacitor; the first end of the inductor is used to connect to the positive electrode of the first DC power supply, the second end of the inductor is connected to the power supply end, and the negative electrode of the first DC power supply is connected to the power ground end and grounded; the positive end of the diode is connected to the second end of the inductor, and the negative end of the diode is connected to the first end of the output capacitor; the second end of the output capacitor is grounded, and the voltage across the output capacitor is the voltage of the second DC power supply, the first end of the output capacitor is also used to connect to the first voltage divider resistor and the second voltage divider resistor in series and then grounded, and the connection between the first voltage divider resistor and the second voltage divider resistor is also electrically connected to the voltage sampling end.

[0013] In some embodiments, the circuit further includes an RC circuit, which includes a resistor and a filter capacitor, wherein the first end of the resistor is connected to the second end of the inductor, the first end of the resistor is connected to the first end of the filter capacitor, and the second end of the filter capacitor is grounded.

[0014] The present invention also provides a switch control chip, comprising the above-mentioned switch control circuit, wherein the power supply end is a power supply pin, the power ground end is a power ground pin, and the voltage sampling end is a voltage sampling pin.

[0015] The beneficial effects of the present invention are as follows: the present invention discloses a switch control circuit, a power conversion circuit and a switch control chip, the switch control circuit includes a power supply end, a power ground end, a voltage sampling end, a switch tube and a gate control circuit; the power supply end and the power ground end are respectively used to be electrically connected to the controlled power conversion module; the drain of the switch tube is connected to the power supply end, the source of the switch tube is connected to the power ground end, and the gate of the switch tube is connected to the output end of the gate control circuit; the input end of the gate control circuit is connected to the voltage sampling end, which is used to control the speed of closing and opening the switch tube and suppress the voltage spike at the power supply end. The present invention controls the speed of closing and opening the switch tube through the gate control circuit, which can effectively reduce the voltage spike at the power supply end, reduce the voltage stress borne by the switch tube, extend its service life, and ensure the normal operation of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a circuit diagram of a switch control circuit of the present invention;

[0017] Figure 2 is a specific circuit diagram of an embodiment of a switch control circuit of the present invention;

[0018] Figure 3 It is a schematic diagram of the circuit structure of a driving control unit in an embodiment of a switch control circuit of the present invention;

[0019] Figure 4 It is a circuit structure diagram of a driving regulating circuit in an embodiment of a switch control circuit of the present invention;

[0020] Figure 5 It is a circuit schematic diagram of a power conversion circuit of the present invention;

[0021] Figure 6 is a circuit diagram of an embodiment of a power conversion circuit of the present invention;

[0022] Figure 7 It is the voltage V of the power supply terminal in multiple circuit operation cycles in a power conversion circuit of the present invention. LX , switch tube current I Q1 , diode current I DIO and the inductor current I IND The timing waveform diagram of

[0023] Figure 8 It is the voltage V of the power supply terminal in the same circuit operation cycle of a power conversion circuit of the present invention. LX , switch tube current I Q1 , diode current I DIO and the inductor current I IND The timing waveform diagram of

[0024] Fig. 9 It is the voltage V corresponding to the power supply terminal when the switch tube is normally closed in the same circuit operation cycle in a power conversion circuit of the present invention. LX , switch tube current I Q1 , diode current I DIO and the inductor current I IND Another timing waveform diagram of ;

[0025] Fig.10 When the speed of closing the switch tube in the same circuit operation cycle in a power conversion circuit of the present invention slows down, the corresponding power supply terminal voltage V LX , switch tube current I Q1 , diode current I DIO and the inductor current I IND Another timing waveform diagram of . DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. Preferred embodiments of the present invention are provided in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0027] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0028] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. The words "include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0029] like Figure 1As shown, a switch control circuit of the present invention is shown, and the switch control circuit includes a power supply terminal LX, a power ground terminal PGND, a voltage sampling terminal FB, a switch tube Q1 (NMOS tube) and a gate control circuit 1; the power supply terminal LX and the power ground terminal PGND are respectively used to electrically connect to the controlled power conversion module; the drain of the switch tube Q1 is connected to the power supply terminal LX, the source of the switch tube Q1 is connected to the power ground terminal PGND, and the gate of the switch tube Q1 is connected to the output end of the gate control circuit 1; the input end of the gate control circuit 1 is connected to the voltage sampling terminal FB, which is used to control the speed of closing and opening the switch tube Q1 and suppress the voltage spike of the power supply terminal LX.

[0030] In this embodiment, the gate control circuit 1 combines the sampling voltage sampled by the voltage sampling terminal FB to control the gate drive voltage Vgate of the switch tube Q1 to increase at a slower speed, and correspondingly slows down the speed of closing and opening the switch tube Q1, thereby suppressing the voltage spike at the power supply terminal LX.

[0031] like Figure 2-Figure 4 As shown, the gate control circuit 1 includes an operational amplifier 11 , a controller 12 , a drive control unit 13 and a drive adjustment circuit 14 .

[0032] The operational amplifier 11 is used to generate a reference voltage V REF and the sampling voltage V input from the voltage sampling terminal FB FB , output voltage of the op amp V EA , so that the controller 12 and the drive control unit 13 receive the operational amplifier output voltage V EA ; The controller 12 and the drive control unit 13 are used to control the drive adjustment circuit 14; the drive control unit 13 includes a first comparator 31 and a second comparator 32, the drive adjustment circuit 14 includes a second drive circuit, a third drive circuit and a first drive circuit, and the first comparator 31 is used to input the op amp output voltage V EA The second comparator 32 is used to compare the input operational amplifier output voltage V EA The voltage V2 is compared with the second reference voltage V2 , and the third driving circuit is controlled together with the controller 12 ; while the first driving circuit is directly controlled by the controller 12 .

[0033] Further, the first driving circuit includes a first PMOS transistor P1 and a first NMOS transistor N1, the second driving circuit includes a second PMOS transistor P2, a third PMOS transistor P3, a second NMOS transistor N2 and a third NMOS transistor N3, and the third driving circuit includes a fourth PMOS transistor P4, a fifth PMOS transistor P5, a fourth NMOS transistor N4 and a fifth NMOS transistor N5. The gates of the second PMOS transistor P2 and the third NMOS transistor N3 are respectively connected to the in-phase output terminal OUT1 and the inverting output terminal OUTB1 of the first comparator 31, and the first comparator 31 controls the two MOS transistors to be turned on. The gates of the fourth PMOS transistor P4 and the fifth NMOS transistor N5 are respectively connected to the in-phase output terminal OUT2 and the inverting output terminal OUTB2 of the second comparator 32, and the second comparator 32 controls the two MOS transistors to be turned on. The gates of the third PMOS transistor P3 , the second NMOS transistor N2 , the fifth PMOS transistor P5 , the fourth NMOS transistor N4 , the first PMOS transistor P1 and the first NMOS transistor N1 are respectively connected to the corresponding output terminals of the controller 12 , and the controller 12 controls the corresponding MOS transistors to be turned on.

[0034] In the first driving circuit, the source of the first PMOS transistor P1 is connected to the driving power supply VDD, the drain of the first PMOS transistor P1 is connected to the drain of the first NMOS transistor N1, and the source of the first NMOS transistor N1 is grounded.

[0035] In the second driving circuit, the source of the second PMOS tube P2 is connected to the driving power supply VDD, the drain of the second PMOS tube P2 is connected to the source of the third PMOS tube P3, the drain of the third PMOS tube P3 is connected to the drain of the second NMOS tube N2, the source of the second NMOS tube N2 is connected to the drain of the third NMOS tube N3, and the source of the third NMOS tube N3 is grounded.

[0036] In the third driving circuit, the source of the fourth PMOS tube P4 is connected to the driving power supply VDD, the drain of the fourth PMOS tube P4 is connected to the source of the fifth PMOS tube P5, the drain of the fifth PMOS tube P5 is connected to the drain of the fourth NMOS tube N4, the source of the fourth NMOS tube N4 is connected to the drain of the fifth NMOS tube N5, and the source of the fifth NMOS tube N5 is grounded.

[0037] Among them, the op amp output voltage V EAWhen the voltage V1 is less than the first reference voltage V1, the in-phase output terminal OUT1 of the first comparator 31 outputs a low level to turn on the second PMOS tube P2, and the inverting output terminal OUTB1 of the first comparator 31 outputs a high level to turn on the third NMOS tube N3; the in-phase output terminal OUT2 of the second comparator 32 outputs a low level to turn on the fourth PMOS tube P4, and the inverting output terminal OUTB2 of the second comparator 32 outputs a high level to turn on the fifth NMOS tube N5; at the same time, the controller 12 outputs a low level to the third PMOS tube P3, the fifth PMOS tube P5 and the first PMOS tube P1, so that the third PMOS tube P3, the fifth PMOS tube P5 and the first PMOS tube P1 are all turned on, and the controller 12 also outputs a high level to the second NMOS tube N2, the fourth NMOS tube N4 and the first NMOS tube N1, so that the second NMOS tube N2, the fourth NMOS tube N4 and the first NMOS tube N1 are turned on. The corresponding second drive circuit, the third drive circuit and the first drive circuit are all turned on, so that the gate drive voltage Vgate of the switch tube Q1 increases fastest at this time, and the corresponding closing and opening speed of the switch tube Q1 is also the fastest.

[0038] The op amp output voltage V EA When the voltage is greater than the first reference voltage V1 and less than the second reference voltage V2, the in-phase output terminal OUT1 of the first comparator 31 outputs a high level to turn off the second PMOS tube P2, and the inverting output terminal OUTB1 of the first comparator 31 outputs a low level to turn off the third NMOS tube N3, and the corresponding second driving circuit is disconnected; the in-phase output terminal OUT2 of the second comparator 32 outputs a low level to turn on the fourth PMOS tube P4, and the inverting output terminal OUTB2 of the second comparator 32 outputs a high level to turn on the fifth NMOS tube N5; at the same time, the controller 12 outputs a low level to the fifth PMOS tube P5 and the first PMOS tube P1, so that the fifth PMOS tube P5 and the first PMOS tube P1 are both turned on, and the controller 12 also outputs a high level to the fourth NMOS tube N4 and the first NMOS tube N1, so that the fourth NMOS tube N4 and the first NMOS tube N1 are turned on. The corresponding third driving circuit and the first driving circuit are turned on, so that the speed at which the gate driving voltage Vgate of the switch tube Q1 increases is slowed down, and the speed at which the switch tube Q1 is turned off and on is also slowed down.

[0039] The op amp output voltage V EAWhen the voltage V2 is greater than the second reference voltage V2, the in-phase output terminal OUT1 of the first comparator 31 outputs a high level, so that the second PMOS tube P2 is turned off, and the inverting output terminal OUTB1 of the first comparator 31 outputs a low level, so that the third NMOS tube N3 is turned off, and the corresponding second drive circuit is disconnected; the in-phase output terminal OUT2 of the second comparator 32 outputs a high level, so that the fourth PMOS tube P4 is turned off, and the inverting output terminal OUTB2 of the second comparator 32 outputs a low level, so that the fifth NMOS tube N5 is turned off, and the corresponding third drive circuit is disconnected; at the same time, the controller 12 outputs a low level to the first PMOS tube P1, so that the first PMOS tube P1 is turned on, and the controller 12 also outputs a high level to the first NMOS tube N1, so that the first NMOS tube N1 is turned on. The corresponding first drive circuit is turned on, so that the gate drive voltage Vgate of the switch tube Q1 increases more slowly at this time, and the speed of the corresponding switch tube Q1 closing and opening becomes slower, thereby effectively suppressing the voltage spike of the power supply terminal LX.

[0040] It should be noted that the reference voltage V REF Generated by the reference voltage source, the sampling voltage V FB Obtained by dividing the power supply voltage output by the controlled power conversion module. EA Characterizes the size of the output load current. The larger the load current, the higher the output voltage V EA The specific values ​​of the first reference voltage V1 and the second reference voltage V2 are mainly set according to the actual situation that the gate control circuit 1 needs to output the gate driving voltage Vgate.

[0041] In some other embodiments, the ratio of drive reduction (the number of drive circuits) can be set according to the actual situation. For power conversion modules that require fine control, more comparators and drive circuits can be set, and the corresponding drive circuits can be controlled to turn on or off by the comparator, so as to achieve more precise control over the speed of closing and opening the switch tube Q1, so that the drive reduction is smoother, thereby effectively suppressing the voltage spike at the switch tube Q1.

[0042] Based on the same inventive concept, Figure 5As shown, the present invention also provides a power conversion circuit, which includes a power conversion module 2 and a switch control circuit 10; the power conversion module 2 is used to access a first DC power supply, and convert the first DC power supply into a second DC power supply output under the action of the switch control circuit 10; the switch control circuit 10 includes a switch tube Q1 and a gate control circuit 1, the drain of the switch tube Q1 is connected to the power conversion module 2 through the power supply terminal LX, and the source of the switch tube Q1 is connected to the power conversion module 2 through the power ground terminal PGND and then grounded; the output end of the gate control circuit 1 is connected to the gate of the switch tube Q1, which is used to control the closing and opening of the switch tube Q1, so that the power conversion module 2 converts the first DC power supply into the second DC power supply, and the gate control circuit 1 is also used to control the closing and opening speed of the switch tube Q1 to be slowed down according to the second DC power supply, so as to suppress the voltage spike at the connection point (power supply terminal LX) between the drain of the switch tube Q1 and the power conversion module 2.

[0043] In this embodiment, the power conversion module 2 is controlled to convert the first DC power supply into the second DC power supply by turning the switch tube Q1 off and on. At the same time, the gate control circuit 1 controls the speed of turning the switch tube Q1 off and on, which can effectively suppress the voltage spike at the connection between the switch tube Q1 and the power conversion module 2 (power supply terminal LX), thereby achieving the purpose of protecting the switch tube Q1.

[0044] like Figure 6 As shown, the power conversion module 2 includes an input capacitor C IN , and the inductor L1, diode D and output capacitor C connected in sequence OUT .

[0045] The positive and negative electrodes of the first DC power supply are connected to the input capacitor C IN The two ends of the input capacitor C IN The voltage at both ends is the voltage of the first DC power supply, and the positive electrode of the first DC power supply is connected in series with the inductor L1 and the switch tube Q1. When the switch tube Q1 is turned on, the first DC power supply charges the inductor L1, and the current on the inductor L1 increases linearly. When the switch tube Q1 is turned off, the inductor L1 discharges, outputs the second DC power supply through the diode D, and the output capacitor C OUT The voltage across the two ends is the voltage of the second DC power supply, and the output capacitor C OUT The two ends are also used to connect the load.

[0046] Specifically, the first end of the inductor L1 is used to connect the positive electrode of the first DC power supply (the input capacitor C IN The first end of the inductor L1 is connected to the drain of the switch tube Q1 through the power supply terminal LX, and the source of the switch tube Q1 is grounded through the power ground terminal PGND and connected to the negative electrode of the first DC power supply (input capacitor C INThe positive terminal of the diode D is connected to the second end of the inductor L1, and the negative terminal of the diode D is connected to the output capacitor C OUT The first end of the output capacitor C OUT The second end of the capacitor is grounded and connected to the negative electrode of the first DC power supply (the input capacitor C IN When the switch tube Q1 is turned off and on for a certain number of times, and then turned off again, the inductor L1 discharges, and outputs the second DC power supply through the diode D, and the output capacitor C OUT The voltage across the two ends is the voltage of the second DC power supply, and the output capacitor C OUT The first end is also used to connect the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 in series and then to be grounded. The connection point between the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 is also electrically connected to the voltage sampling terminal FB.

[0047] Among them, after the power conversion module 2 is connected to the first DC power supply, when the gate control circuit 1 controls the switch tube Q1 to turn on, the first DC power supply charges the inductor L1, and the current on the inductor L1 increases linearly. At this time, the inductor L1 stores energy, and due to the current retention characteristics of the inductor L1, the charging current is basically constant, corresponding to the left side of the inductor L1 is positive, and the right side is negative. When the gate control circuit 1 controls the switch tube Q1 to turn off, since the current of the inductor L1 does not change suddenly, the inductor L1 releases the stored energy at this time, and the inductor L1 and the first DC power supply pass through the diode D to output the second DC power supply to supply power to the load, thereby achieving a boost effect. At this time, the current of the inductor L1 gradually decreases, corresponding to the right side of the inductor L1 is positive, and the left side is negative.

[0048] In this embodiment, by using the output capacitor C OUT The discharge voltage of the inductor L1 and the voltage of the first DC power supply are superimposed by electronic components such as a diode D, so that the output voltage is increased to obtain a corresponding second DC power supply.

[0049] like Figure 6 As shown, the power conversion module 2 also includes an RC circuit, and the RC circuit includes a resistor R LX And filter capacitor C LX , resistor R LX The first end of the inductor L1 is connected to the second end of the resistor R LX The first end of the filter capacitor C LX The first end of the filter capacitor C LX The second end of the resistor R LX For filtering capacitor C LX Charging reduces the voltage spike at the connection point between the inductor L1 and the switch tube Q1 (power supply terminal LX).

[0050] In this embodiment, the resistor R LX To filter capacitor CLX Charging slows down the voltage rise at the power supply terminal LX, thereby reducing the voltage spike at this point.

[0051] Combination Figure 6 It can be seen that the power conversion module 2 forms a boost circuit by connecting the switch tube Q1, and uses the inductor L1 and the output capacitor C OUT The energy storage characteristics of the switch tube Q1 perform high-frequency switching actions to store the input electrical energy in the inductor L1 and the output capacitor C OUT In the circuit, when the switch tube Q1 is turned off, the electrical energy is released to the load to provide the required voltage.

[0052] like Figure 7 As shown, multiple operating cycles T are shown. P Internal power supply voltage V LX , switch tube current I Q1 , diode current I DIO and the inductor current I IND The waveform changes as a whole. When the switch tube Q1 is turned on (Ton), the voltage V corresponding to the power supply terminal LX is LX is 0; corresponding to the current I flowing through the switch tube Q1 Q1 and the current I flowing through the inductor L1 IND are basically the same, and both gradually increase until they reach their highest point when the switch tube Q1 is turned off; at this time, the diode D and the output capacitor C OUT Both are short-circuited, corresponding to the current I flowing through the diode D DIO When the switch tube Q1 is turned off (Toff), the voltage V LX reaches its maximum; at this time, the current I flowing through the switch tube Q1 Q1 is 0; due to the current I IND No sudden change, so the current I flowing through the inductor L1 IND Gradually decreases; at the same time, since the inductor L1 and the diode D are connected in series at this time, the corresponding current I flowing through the diode D DIO The current I flowing through the inductor L1 IND same.

[0053] It should be noted that when the switch tube Q1 is turned off and on, the appearance / change of voltage and current is not a sudden process, but a gradual change, but the change time is very short.

[0054] like Figure 8 As shown, it shows the voltage V of the power supply terminal in the same operation cycle LX , switch tube current I Q1 , diode current I DIO and the inductor current I INDThe actual waveform changes. In the process of the switch tube Q1 gradually turning off, the switch tube current I flowing through the switch tube Q1 Q1 Gradually decreases, the diode current I flowing through the diode D DIO Gradually increases. Because the inductor current I flowing through the inductor L1 IND No sudden change, so the switch tube current I Q1 and the diode current I DIO The sum of the inductor current I IND Slightly smaller, resulting in a voltage spike at the power supply terminal LX.

[0055] like Fig. 9 and Fig.10 As shown, the corresponding switch tube current I Q1 , diode current I DIO and the inductor current I IND The actual waveform changes are moved to the same line graph (inductor current I IND It can be seen from the timing waveform diagram that ΔV LX >ΔV ’ LX , that is, the switch tube current I Q1 When the reduction time becomes longer, the voltage peak at the corresponding power supply terminal LX becomes lower. At this time, the speed of closing the corresponding switch tube Q1 is slowed down, so that the switch tube current I flowing through the switch tube Q1 Q1 The process of gradual decrease becomes slower. At the same time, because the diode D is passive, the diode current I flowing through the diode D DIO If the increasing speed remains unchanged, the difference between the current flowing into and out of the power supply terminal LX will not be that large, and the voltage spike at the power supply terminal LX will be reduced.

[0056] It should be noted that the inductor current I flowing through the inductor L1 IND The larger the value, the greater the overshoot at the power supply terminal LX, which may exceed the withstand voltage of Q1. At the same time, the larger the driving current flowing into the gate of the switch tube Q1 through the driving adjustment circuit 14, the faster the state of the switch tube Q1 changes (the faster it turns on and off). As the inductor current I flowing through the inductor L1 IND becomes high, the corresponding driving circuit needs to be turned off to reduce the driving current flowing into the gate of the switch tube Q1, thereby reducing the closing speed of the switch tube Q1, thereby achieving the effect of suppressing the voltage spike at the power supply terminal LX.

[0057] In this application, the power supply voltage V LX The voltage difference at the peak is ΔV LX As the output inductor current I IND increases with the increase of the voltage difference ΔV LXThis directly limits the operating voltage range of the switch tube Q1. At the same time, the output voltage V EA The level of V determines the driving capability of the driving control unit 13. EA The higher the value, the higher the corresponding drive current. Every time the drive current exceeds a threshold value (the op amp output voltage V EA is greater than the reference voltage of the corresponding comparator), a driving circuit is turned off, thereby controlling the opening and closing speed of the switch tube Q1 to be slowed down, thereby dynamically adjusting the voltage spike of the power supply terminal LX.

[0058] In some other embodiments, the power conversion module 2 can also form a step-down circuit by connecting the switch control circuit 10, and can also control the voltage spikes at the connection points between the switch tube Q1 and the first DC power supply and the power conversion module 2 respectively through the gate control circuit 1.

[0059] Based on the same inventive concept, the present invention also provides a switch control chip, including the aforementioned switch control circuit, wherein the power supply end is a power supply pin, the power ground end is a power ground pin, and the voltage sampling end is a voltage sampling pin.

[0060] In the present application, other technical features in the above-mentioned switch control chip are the same as the features disclosed in the above-mentioned switch control circuit embodiment, and will not be repeated here.

[0061] In the present application, the above-mentioned switch control circuit, power conversion circuit and switch control chip go deep into the essence of the switch action, control the switch switching slope, and make the energy change in the power conversion circuit smoother by accurately controlling the speed of switch on and off, thereby effectively reducing the voltage spike at the switch node. This switch control circuit can not only significantly reduce the voltage stress borne by the switch device and extend its service life, but also reduce electromagnetic interference and improve the stability, reliability and compatibility of the entire circuit system. Furthermore, due to the suppression of voltage spikes, the energy transmission and conversion process is smoother, reducing energy loss, so that the entire power conversion circuit can maintain a higher efficiency within a wider load range. In addition, the above-mentioned voltage spike suppression circuit can also better adapt to different load requirements, achieve a wider range of stable output voltages, and provide more flexible power support for various electronic devices.

[0062] It can be seen that the present invention discloses a switch control circuit, a power conversion circuit and a switch control chip, the switch control circuit includes a power supply end, a power ground end, a voltage sampling end, a switch tube and a gate control circuit; the power supply end and the power ground end are respectively used to be electrically connected to the controlled power conversion module; the drain of the switch tube is connected to the power supply end, the source of the switch tube is connected to the power ground end, and the gate of the switch tube is connected to the output end of the gate control circuit; the input end of the gate control circuit is connected to the voltage sampling end, which is used to control the speed of closing and opening the switch tube and suppress the voltage spike at the power supply end. The present invention controls the speed of closing and opening the switch tube through the gate control circuit, which can effectively reduce the voltage spike at the power supply end, reduce the voltage stress borne by the switch tube, extend its service life, and ensure the normal operation of the circuit.

[0063] The above are only embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent structural transformations made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are included in the protection scope of the present invention.

Claims

1. A switch control circuit, characterized in that: The switch control circuit includes a power supply terminal, a power ground terminal, a voltage sampling terminal, a switch tube and a gate control circuit; The power supply terminal and the power ground terminal are respectively used to be electrically connected to a controlled power conversion module; The drain of the switch tube is connected to the power supply end, the source of the switch tube is connected to the power ground end, and the gate of the switch tube is connected to the output end of the gate control circuit; The input end of the gate control circuit is connected to the voltage sampling end, and is used to control the speed of closing and opening the switch tube, thereby suppressing the voltage spike at the power supply end.

2. The switch control circuit according to claim 1, characterized in that: The gate control circuit includes an operational amplifier, a controller, a drive control unit and a drive adjustment circuit; The operational amplifier is used to output an operational amplifier output voltage according to a reference voltage and a sampling voltage; wherein the reference voltage is generated by a reference voltage source, and the sampling voltage is obtained by sampling at the voltage sampling terminal; The controller and the drive control unit are respectively used to receive the op amp output voltage, the drive control unit includes a first comparator, the drive regulation circuit includes a first drive circuit and a second drive circuit, the first comparator is used to compare the input op amp output voltage with a first reference voltage, and control the second drive circuit together with the controller; the controller is also used to control the first drive circuit.

3. The switch control circuit according to claim 2, characterized in that: The first driving circuit includes a first PMOS tube and a first NMOS tube; the gates of the first PMOS tube and the first NMOS tube are respectively connected to the output ends corresponding to the controller, the source of the first PMOS tube is connected to the driving power supply, the drain of the first PMOS tube is connected to the drain of the first NMOS tube, and the source of the first NMOS tube is grounded.

4. The switch control circuit according to claim 2, characterized in that: The second driving circuit includes a second PMOS tube, a third PMOS tube, a second NMOS tube and a third NMOS tube; the gates of the second PMOS tube and the second NMOS tube are respectively connected to the in-phase output terminal and the inverting output terminal of the first comparator, the gates of the third PMOS tube and the third NMOS tube are respectively connected to the corresponding output terminals of the controller, the source of the second PMOS tube is connected to the driving power supply, the drain of the second PMOS tube is connected to the source of the third PMOS tube, the drain of the third PMOS tube is connected to the drain of the second NMOS tube, the source of the second NMOS tube is connected to the drain of the third NMOS tube, and the source of the third NMOS tube is grounded.

5. The switch control circuit according to claim 2, characterized in that: The driving control unit further includes a second comparator, and the driving regulation circuit further includes a third driving circuit. The second comparator is used to compare the inputted operational amplifier output voltage with a second reference voltage, and controls the third driving circuit together with the controller.

6. The switch control circuit according to claim 5, characterized in that: The third driving circuit includes a fourth PMOS tube, a fifth PMOS tube, a fourth NMOS tube and a fifth NMOS tube; the gates of the fourth PMOS tube and the fourth NMOS tube are respectively connected to the in-phase output terminal and the inverting output terminal of the second comparator, the gates of the fifth PMOS tube and the fifth NMOS tube are respectively connected to the corresponding output terminals of the controller, the source of the fourth PMOS tube is connected to the driving power supply, the drain of the fourth PMOS tube is connected to the source of the fifth PMOS tube, the drain of the fifth PMOS tube is connected to the drain of the fourth NMOS tube, the source of the fourth NMOS tube is connected to the drain of the fifth NMOS tube, and the source of the fifth NMOS tube is grounded.

7. A power conversion circuit, characterized in that: The power conversion circuit includes a power conversion module and a switch control circuit as described in any one of claims 1-6, wherein the power conversion module is used to connect to a first DC power supply and convert the first DC power supply into a second DC power supply output under the action of the switch control circuit.

8. The power conversion circuit according to claim 7, characterized in that: The power conversion module includes an inductor, a diode and an output capacitor; The first end of the inductor is used to connect the positive electrode of the first DC power supply, the second end of the inductor is connected to the power supply end, and the negative electrode of the first DC power supply is connected to the power ground end and grounded; The positive terminal of the diode is connected to the second terminal of the inductor, and the negative terminal of the diode is connected to the first terminal of the output capacitor; The second end of the output capacitor is grounded, and the voltage across the output capacitor is the voltage of the second DC power supply. The first end of the output capacitor is also used to connect the first voltage-dividing resistor and the second voltage-dividing resistor in series and then to ground. The connection between the first voltage-dividing resistor and the second voltage-dividing resistor is also electrically connected to the voltage sampling end.

9. The power conversion circuit according to claim 7, characterized in that: The power conversion module further includes an RC circuit, wherein the RC circuit includes a resistor and a filter capacitor; The first end of the resistor is connected to the second end of the inductor, the first end of the resistor is connected to the first end of the filter capacitor, and the second end of the filter capacitor is grounded.

10. A switch control chip, characterized in that: The switch control circuit comprises the switch control circuit according to any one of claims 1 to 6, wherein the power supply terminal is a power supply pin, the power ground terminal is a power ground pin, and the voltage sampling terminal is a voltage sampling pin.

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