Voltage conversion circuit compatible with buck and boost and switching power supply conversion chip

Abstract

The embodiment of the invention provides a voltage conversion circuit compatible with step-down and step-up and a switching power supply conversion chip, and the circuit comprises a main circuit which is configured to receive an input voltage and adjust an output voltage through the charging and discharging control of an inductor coupled with the input voltage; a mode control circuit configured to output a first voltage signal or a second voltage signal according to a magnitude relationship between the input voltage and the output voltage; the first transistor is coupled between the main circuit and the output voltage and is configured to control the grid voltage of the first transistor by the voltage signal output by the mode control circuit; the voltage loop control circuit is configured to generate control signals for controlling switches of a first power tube and a second power tube in the main circuit according to feedback of the output voltage and the reference voltage; and the protection circuit is configured to protect the first power tube. The problems that a large surge current passes through from input to output after an existing BOOST type circuit is powered on, the voltage obtained during compatible voltage reduction is inverted, and the soft start process of voltage boosting is not smooth are solved.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of power supply technology, and in particular, to a voltage conversion circuit and a switching power supply conversion chip that are compatible with voltage reduction and voltage increase. Background Art

[0002] The BOOST circuit is a switching DC boost circuit that converts the input voltage into a higher output voltage by setting the reference voltage and feedback factor. The main structure and connection relationship of the BOOST circuit are as follows: Figure 1 As shown, it includes an inductor L1, two power tubes (MLS, MHS), feedback network and control circuit. Among them, D1 and D2 are parasitic diodes of the two power tubes respectively.

[0003] Depend on Figure 1 It can be seen that in the BOOST type circuit, there is a path from input to output composed of inductor L1 and diode D2, which will cause a large surge current to pass through this path after the input is powered on, causing the output voltage to rise to slightly lower than the input. This is a phenomenon that the application end of the BOOST type circuit does not want to see. A normal BOOST type circuit startup process should be controlled by an enable signal. After the input is powered on and before the enable signal is enabled, there is no path from input to output. After the enable signal is enabled, the BOOST type circuit starts soft start, and the output voltage rises in a controlled manner. In response to the above problems, the current existing solutions are usually solved by switching the body connection relationship of the high-side power tube MHS so that its body end is connected to the drain or source end to switch the direction of the parasitic diode D2. However, the current solution will reduce the robustness of the circuit and increase the complexity of the design.

[0004] In addition, although BOOST is a step-up circuit, in some cases it needs to be combined with a step-up or step-down application. In response to this application requirement, the usual solution is to use a BUCK-BOOST circuit. For a conventional two-tube BUCK-BOOST circuit, its output voltage is inversely proportional to the input voltage, which is very inconvenient to use. For example, if you want to implement a 3.3V to 5V BOOST function, when the input voltage is 3.3V, you can only output a -5V voltage instead of 5V. For a 4-tube BUCK-BOOST circuit, 4 power tubes are required, which greatly increases the cost and the complexity of the design.

[0005] In addition, for Figure 1In the BOOST boost circuit, during the soft start process, the traditional solution is to control the gate voltage of MHS to achieve constant current to charge the output until a certain time has passed, and then switch the gate of MHS to 0V or the input voltage Vin, and continue the soft start process through the voltage loop until the output voltage rises to the target value. The inventor found that this soft start control method will cause the soft start process to be uneven, because in the first constant current charging stage, the slope of the output voltage rise is different from that in the second voltage loop control stage. Therefore, after the constant current is charged to the point where the output voltage is equal to the input voltage, the output voltage will be maintained for a period of time before continuing to rise. Figure 2 As shown in the corresponding simulation waveform, the problem with this soft start control method is that the output voltage will remain equal to the input voltage for a period of time, and this time will also change with the load conditions. During this period of time, the output voltage does not actually reach the target voltage, so for the subsequent circuit, it may be in an abnormal working state at this time. Summary of the invention

[0006] The embodiments described herein provide a voltage conversion circuit and a switching power supply conversion chip that are compatible with both step-down and step-up, in order to solve the problems existing in the above-mentioned BOOST-type boost circuit.

[0007] According to a first aspect of the present disclosure, a voltage conversion circuit compatible with buck and boost is provided, the voltage conversion circuit comprising: a main circuit, a first transistor, a mode control circuit, a voltage loop control circuit, and a protection circuit, wherein the main circuit is configured to receive an input voltage, adjust the output voltage by controlling the charge and discharge of an inductor coupled to the input voltage, and realize the charge and discharge control of the inductor by switching control of a first power tube and a second power tube coupled to the inductor; the mode control circuit is configured to output a first voltage signal when the output voltage is less than the input voltage, and output a second voltage signal when the output voltage is equal to or greater than the input voltage; the first transistor is coupled to the Between the main circuit and the output voltage, it is configured to use the first voltage signal or the second voltage signal as the control electrode signal of the first transistor, so that the first transistor works in different working states and realizes the boost or buck of the voltage conversion circuit; the voltage loop control circuit is configured to generate a first control signal and a second control signal according to the feedback of the output voltage and the reference voltage, and output the first control signal and the second control signal to the main circuit to control the switches of the first power tube and the second power tube respectively, so that the output voltage is stabilized to the target voltage value; the protection circuit is coupled to the first power tube, and is configured to protect the gate-source voltage of the first power tube from exceeding the maximum gate-source voltage.

[0008] Optionally, the mode control circuit includes: a mode control module and a first driver, wherein the mode control module is configured to generate a mode control signal based on a magnitude relationship between an output voltage and an input voltage; and the first driver is configured to output a corresponding mode voltage based on a level state of the mode control signal, and the mode voltage includes the first voltage signal and the second voltage signal.

[0009] Optionally, the mode control module includes: a first voltage-dividing resistor string, a second voltage-dividing resistor string, a first comparator, and a first inverter, wherein the first voltage-dividing resistor string is coupled to the input voltage and is configured to detect the input voltage, and couple the obtained input voltage detection result to the negative input terminal of the first comparator; the second voltage-dividing resistor string is coupled to the output voltage and is configured to detect the output voltage, and couple the obtained output voltage detection result to the positive input terminal of the first comparator; the output terminal of the first comparator is coupled to the input terminal of the first inverter, and the output terminal of the first inverter outputs the mode control signal.

[0010] Optionally, the first end of the first driver is coupled to the mode control signal, the second end of the first driver outputs the first voltage signal or the second voltage signal, the third end of the first driver is coupled to the first voltage signal, and the fourth end of the first driver is coupled to the second voltage signal, wherein when the level state of the mode control signal is high, the first voltage signal is output, and when the level state of the mode control signal is low, the second voltage signal is output.

[0011] Optionally, the first transistor is a P-type MOS transistor, the first voltage signal is equal to the input voltage, and the second voltage signal is zero voltage.

[0012] Optionally, the main circuit includes the inductor, the first power tube, and the second power tube, wherein one end of the inductor is coupled to the input voltage, and the other end of the inductor is respectively coupled to the first pole of the first power tube and the first pole of the second power tube; the second pole of the first power tube is respectively coupled to the protection circuit and the second pole of the first transistor, and the control pole of the first power tube is coupled to the first control signal; the second pole of the second power tube is coupled to the ground terminal, and the control pole of the second power tube is coupled to the second control signal.

[0013] Optionally, the voltage loop control circuit includes: a third voltage-dividing resistor string, a current source, a capacitor, an error amplifier, a second comparator, a trigger, a second driver, a third driver, and a second inverter, wherein the third voltage-dividing resistor string is respectively coupled to the output voltage and the first input terminal of the error amplifier; one end of the current source is coupled to the power supply voltage, the other end of the current source is respectively coupled to one end of the capacitor and the second input terminal of the error amplifier, and the other end of the capacitor is coupled to the ground terminal; the third input terminal of the error amplifier is coupled to the reference voltage, and the output terminal of the error amplifier is coupled to the negative input terminal of the second comparator; the positive input terminal of the second comparator is coupled to the slope compensation signal, and the output terminal of the second comparator is coupled to the reset input terminal of the trigger; the set input terminal of the trigger is coupled to the clock signal, and the output terminal of the trigger is respectively coupled to the input terminal of the second driver and the input terminal of the second inverter; the output terminal of the second driver outputs the second control signal; the output terminal of the second inverter is coupled to the input terminal of the third driver, and the output terminal of the third driver outputs the first control signal.

[0014] Optionally, the protection circuit includes: a voltage regulator diode, wherein the positive electrode of the voltage regulator diode is coupled to the ground terminal, and the negative electrode of the voltage regulator diode is coupled to the second electrode of the first power tube and the second electrode of the first transistor respectively.

[0015] Optionally, the target voltage value corresponding to the voltage conversion circuit when implementing voltage boost or voltage reduction is different, and the ratio between the resistors in the third voltage-dividing resistor string is adjusted according to the target voltage value.

[0016] According to a second aspect of the present disclosure, a switching power supply conversion chip is provided, wherein the switching power supply conversion chip comprises a voltage conversion circuit compatible with step-down and step-up as described in any one of the above-mentioned first aspects.

[0017] In the voltage conversion circuit and switching power supply conversion chip compatible with bucking and boosting of the disclosed embodiment, a first transistor and a mode control circuit are mainly added. The mode control circuit can generate a first voltage signal or a second voltage signal according to the magnitude relationship between the output voltage and the input voltage. The obtained first voltage signal or the second voltage signal is used as the control electrode signal of the first transistor, so that the first transistor works in different working states, and cooperates with the voltage loop control circuit to realize the boost or buck of the voltage conversion circuit, and can ensure that the output voltage is in phase with the input voltage, and smooth soft start during the boost function. In addition, before the voltage conversion circuit is enabled after power-on, the control electrode voltage of the first transistor can also be controlled to isolate the current path between the input and output, so as to avoid raising the output voltage to slightly lower than the input voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure, wherein: Figure 1 A circuit diagram of an existing BOOST type circuit is shown; Figure 2 A schematic diagram of simulation waveform corresponding to an existing BOOST type circuit soft start is shown; Figure 3 A schematic block diagram of a voltage conversion circuit compatible with voltage reduction and voltage increase according to an embodiment of the present disclosure is shown; Figure 4 A schematic block diagram of another voltage conversion circuit compatible with voltage reduction and voltage increase according to an embodiment of the present disclosure is shown; Figure 5 A waveform diagram of a soft start corresponding to a voltage conversion circuit compatible with buck and boost in a boost application in an embodiment of the present disclosure is shown; Figure 6 An exemplary circuit diagram of a mode control circuit in an embodiment of the present disclosure is shown; Figure 7 A schematic block diagram of another voltage conversion circuit compatible with buck and boost according to an embodiment of the present disclosure is shown; The elements in the drawings are schematic and not drawn to scale. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meanings as those commonly understood by those skilled in the art to which the subject matter of the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the specification and the relevant technology, and will not be interpreted in an idealized or overly formal form unless otherwise clearly defined herein. As used herein, statements that two or more parts are "connected" or "coupled" together should refer to these parts being directly combined together or combined through one or more intermediate components. In addition, terms such as "first" and "second" are only used to distinguish one component (or a part of a component) from another component (or another part of a component).

[0021] In all embodiments of the present disclosure, since the source and drain of a metal oxide semiconductor (MOS) transistor are symmetrical, and the conduction current directions between the source and drain of an N-type transistor and a P-type transistor are opposite, in the embodiments of the present disclosure, the controlled middle terminal of the MOS transistor is referred to as a control terminal, and the remaining two terminals of the MOS transistor are referred to as a first terminal and a second terminal, respectively. In addition, terms such as "first" and "second" are only used to distinguish one component (or a portion of a component) from another component (or another portion of a component).

[0022] In order to solve the problems existing in the existing BOOST type circuits, such as a large surge current passing from input to output after power-on, voltage inversion obtained when compatible with step-down, and uneven soft start process of boost, a new voltage conversion circuit structure compatible with step-down and step-up is proposed. The compatible step-down and voltage conversion circuit of the disclosed embodiment is an improvement on the existing BOOST type circuit with two power tube structures, adding a first transistor and a mode control circuit, and achieving compatibility and smooth soft start of step-up and step-down applications by controlling the control electrode voltage of the first transistor. At the same time, the path from input to output is isolated before enabling, thereby achieving isolation between input and output after power-on and before enabling. The compatible step-down and step-up voltage conversion circuit of the disclosed embodiment is described in detail below.

[0023] Figure 3 A schematic block diagram of a voltage conversion circuit 100 compatible with buck and boost according to an embodiment of the present disclosure is shown. Figure 3 As shown, the voltage conversion circuit 100 compatible with buck and boost includes: a main circuit 110, a first transistor M1, a mode control circuit 120, a voltage loop control circuit 130, and a protection circuit 140. The main circuit 110 is configured to receive an input voltage Vin, adjust an output voltage Vout by controlling the charge and discharge of an inductor L coupled to the input voltage Vin, and realize the charge and discharge control of the inductor L by controlling the switching of a first power tube MHS and a second power tube MLS coupled to the inductor L; The present application is an improvement on the existing BOOST circuit. The structure of the main circuit 110 of the present application embodiment is the same as the main circuit 110 of the existing two-power tube BOOST circuit structure. Figure 4 As shown, the main circuit 110 includes an inductor L, a first power tube MHS, and a second power tube MLS, wherein one end of the inductor L is coupled to the input voltage Vin, and the other end of the inductor L is respectively coupled to the first pole of the first power tube MHS and the first pole of the second power tube MLS; the second pole of the first power tube MHS is respectively coupled to the protection circuit 140 and the second pole of the first transistor M1, and the control pole of the first power tube MHS is coupled to the first control signal VG_H; the second pole of the second power tube MLS is coupled to the ground end, and the control pole of the second power tube MLS is coupled to the second control signal VG_L. The first control signal VG_H controls the switch of the first power tube MHS, and the second control signal VG_L controls the switch of the second power tube MLS. During the charging process, the second control signal VG_L controls the second power tube MLS to close, and the first control signal VG_H controls the first power tube MHS to turn off. The input voltage Vin charges the inductor L, and the current on the inductor L increases linearly at a certain ratio. This ratio is related to the size of the inductor L. As the current of the inductor L increases, some energy is stored in the inductor L; during the discharging process, the second control signal VG_L controls the second power tube MLS to turn off, and the first control signal VG_H controls the first power tube MHS to close, and the energy in the inductor L is slowly released through a new path; the continuous charging and discharging process of the inductor L can adjust the output voltage Vout.

[0024] The mode control circuit 120 is to control the control electrode voltage (gate voltage) of the first transistor M1, thereby controlling the working state of the first transistor M1, and then controlling the voltage conversion circuit compatible with buck and boost to realize the boost or buck function. The mode control circuit 120 generates a voltage control signal that can control the first transistor M1 to different working states according to the magnitude relationship between the input voltage Vin and the output voltage Vout. Specifically, the mode control circuit 120 is configured to output a first voltage signal V1 when the output voltage Vout is less than the input voltage Vin, and output a second voltage signal V2 when the output voltage Vout is equal to or greater than the input voltage Vin. Furthermore, in the embodiment of the present application, the first voltage signal V1 is equal to the input voltage Vin, and the second voltage signal V2 is zero voltage.

[0025] The first transistor M1 is coupled between the main circuit 110 and the output voltage Vout, and is configured to use the first voltage signal V1 or the second voltage signal V2 as the control electrode signal of the first transistor M1, so that the first transistor M1 works in different working states and realizes the boost or buck of the voltage conversion circuit. In the embodiment of the present application, the first transistor M1 is a P-type MOS tube. During the boost function, the output voltage Vout is higher than the input voltage Vin, the mode control circuit 120 outputs the second voltage signal V2, and the second voltage signal V2 is zero voltage, then the control electrode voltage of the first transistor M1 is zero, and the first transistor M1 works in the deep linear region, which is equivalent to a small resistor. Through the periodic switching of the first power tube MHS and the second power tube MLS, the output voltage Vout can be adjusted to the target voltage value. During the buck function, the output voltage Vout is lower than the input voltage Vin, and the mode control circuit 120 outputs the first voltage signal V1. The first voltage signal V1 is the input voltage Vin, and the control electrode voltage of the first transistor M1 is the input voltage Vin. The first transistor M1 works in the saturation region. Through the periodic switching of the first power tube MHS and the second power tube MLS, the voltage at point A can be raised to a voltage value higher than the input voltage Vin. After that, the first transistor M1 is turned on, and the output voltage Vout will gradually approach the target voltage value. At this time, the voltage at point A is determined by the load current and Vin, that is, the voltage at point A is Vin plus the gate-source voltage VGS of the first transistor M1. In addition, the first transistor M1 can also isolate the input and output before enabling after the circuit is powered on, and suppress the surge current.

[0026] The voltage loop control circuit 130 is configured to generate a first control signal VG_H and a second control signal VG_L according to feedback of the output voltage Vout and a reference voltage Vref, and output the first control signal VG_H and the second control signal VG_L to the main circuit 110 to respectively control the switching of the first power tube MHS and the second power tube MLS, so that the output voltage Vout is stabilized to a target voltage value. The voltage loop control circuit 130 in the present application has the same structure as the voltage loop control circuit 130 in the existing BOOST circuit, and both obtain a switch control signal according to feedback of the output voltage Vout, a reference voltage Vref, and a slope compensation signal Vramp, so as to control the switching of the first power tube MHS and the second power tube MLS, so that the output voltage Vout is equal to the target voltage value. Specifically, as Figure 4As shown, the voltage loop control circuit 130 includes a third voltage-dividing resistor string 131, a current source I, a capacitor C, an error amplifier EA, a second comparator Comp2, a trigger 132, a second driver Driver2, a third driver Driver3, and a second inverter NOT2, wherein the third voltage-dividing resistor string 131 is respectively coupled to the output voltage Vout and the first input terminal of the error amplifier EA, and the third voltage-dividing resistor string 131 is used to obtain a feedback voltage of the output voltage Vout; one end of the current source I is coupled to the power supply voltage VDD, and the other end of the current source I is respectively coupled to one end of the capacitor C and the second input terminal of the error amplifier EA, and the other end of the capacitor C is coupled to the ground terminal; the third input terminal of the error amplifier EA is coupled to the reference voltage Vref, and the error The output of the differential amplifier EA is coupled to the negative input of the second comparator Comp2; the positive input of the second comparator Comp2 is coupled to the slope compensation signal Vramp, the output of the second comparator Comp2 is coupled to the reset input R of the trigger 132; the set input S of the trigger 132 is coupled to the clock signal Clk, the output Q of the trigger 132 is respectively coupled to the input of the second driver Driver2 and the input of the second inverter NOT2; the output of the second driver Driver2 outputs the second control signal VG_L; the output of the second inverter NOT2 is coupled to the input of the third driver Driver3, and the output of the third driver Driver3 outputs the first control signal VG_H. It should be noted that the target voltage values ​​are different under the boost function and the buck function, and the ratio between the resistors in the third voltage-dividing resistor string 131 is adjusted according to the target voltage value.

[0027] The protection circuit 140 is coupled to the first power tube MHS in the main circuit 110, and is configured to protect the gate-source voltage of the first power tube MHS from exceeding the maximum gate-source voltage. The protection circuit 140 in the embodiment of the present application is mainly used to protect the first power tube MHS. For example, in the aforementioned analysis of the step-down function, the gate voltage of the first transistor M1 is Vin, and the voltage at point A is Vin+the gate-source voltage VGS of the first transistor M1. When the first power tube MHS is to be turned on, the control electrode voltage of the first power tube MHS is zero. At this time, the gate-source voltage of the first power tube MHS will be relatively large, and may exceed the maximum gate-source voltage of the first power tube MHS. Therefore, it is necessary to add the protection circuit 140 to protect it.

[0028] Combination Figure 3-4The working principle of the voltage conversion circuit 100 compatible with buck and boost in the embodiment of the present application is explained: after the voltage conversion circuit 100 compatible with buck and boost is powered on and before it is enabled, Vout is zero, and Vout is less than Vin, so the mode control circuit 120 outputs a second voltage signal V2, and the second voltage signal V2 is equal to Vin. The direction of the parasitic diode D3 of M1 is opposite to the direction of the parasitic diode D1 of MHS, so the current path between Vin and Vout can be isolated through M1, thereby isolating the input and output and suppressing surge current. After the circuit is enabled, it enters the soft start. At the beginning, Vout is 0, which is lower than Vin. The mode control circuit 120 outputs the second voltage signal V2 equal to Vin, the gate voltage of M1 is Vin, and M1 works in the saturation region. As I charges C (also the soft start capacitor C) and the voltage loop control circuit 130 works, Vout rises linearly. If the target voltage value is less than Vin, that is, it is a step-down application, then when Vout rises to equal the target voltage value, the soft start ends; if the target voltage value is greater than Vin, that is, it is a step-up application, the soft start has not ended. When Vout rises to equal Vin, the mode control circuit 120 outputs the first voltage signal V1 equal to zero voltage, the gate voltage of M1 is zero voltage, and M1 works in the deep linear region. After that, Vout continues to rise until it is equal to the target voltage value, and the soft start ends. In the soft start process of the step-up application, Vout rises linearly, and there is no such thing as in the prior art. Figure 2 The plateau time shown (the output voltage Vout will remain equal to the input voltage Vin for a period of time) achieves a smooth soft start. Figure 5 , which is a waveform diagram of the soft start corresponding to the voltage conversion circuit compatible with buck and boost in the embodiment of the present application in boost application. Figure 5 It can also be seen that Vout rises linearly before reaching the target voltage value. Figure 2 As shown in the platform time, in addition, Vout and Vin are in phase, which is more convenient to apply compared to the prior art in which Vout and Vin are in anti-phase.

[0029] From the above description, it can be seen that in the voltage conversion circuit compatible with buck and boost of the embodiment of the present disclosure, a first transistor M1 and a mode control circuit 120 are added. The mode control circuit 120 can generate a first voltage signal V1 or a second voltage signal V2 according to the magnitude relationship between the output voltage Vout and the input voltage Vin. The obtained first voltage signal V1 or the second voltage signal V2 is used as the control electrode signal of the first transistor M1, so that the first transistor M1 works in different working states, and cooperates with the voltage loop control circuit to realize the boost or buck of the voltage conversion circuit, and can ensure that the output voltage Vout is in phase with the input voltage Vin, and smooth soft start during the boost function. In addition, before the voltage conversion circuit is enabled after power-on, the current path between the input and output can be isolated by controlling the control electrode voltage of the first transistor M1.

[0030] Further, such as Figure 6 As shown, the mode control circuit 120 includes: a mode control module 121 and a first driver Driver1, wherein the mode control module 121 is configured to generate a mode control signal MODE according to a magnitude relationship between an output voltage Vout and an input voltage Vin; the first driver Driver1 is configured to output a corresponding mode voltage according to a level state of the mode control signal MODE, and the mode voltage includes the first voltage signal V1 and the second voltage signal V2.

[0031] Further, such as Figure 6 As shown, the mode control module includes: a first voltage-dividing resistor string 1211, a second voltage-dividing resistor string 1212, a first comparator Comp1, and a first inverter NOT1, wherein the first voltage-dividing resistor string 1211 is coupled to the input voltage Vin, and is configured to detect the input voltage Vin, and couple the obtained input voltage Vin detection result to the negative input terminal of the first comparator Comp1; the second voltage-dividing resistor string 1212 is coupled to the output voltage Vout, and is configured to detect the output voltage Vout, and couple the obtained output voltage Vout detection result to the positive input terminal of the first comparator Comp1; the output terminal of the first comparator Comp1 is coupled to the input terminal of the first inverter NOT1, and the output terminal of the first inverter NOT1 outputs the mode control signal MODE. The first voltage-dividing resistor string 1211 and the second voltage-dividing resistor string 1212 are both composed of two series resistors. Specifically, according to Figure 6 From the working principle of the mode control module, it can be obtained that when the output voltage Vout is less than the input voltage Vin, the mode control signal MODE is at a high level; when the output voltage Vout is greater than or equal to the input voltage Vin, the mode control signal MODE is at a low level.

[0032] like Figure 6 The first end of the first driver Driver1 is coupled to the mode control signal MODE, the second end of the first driver Driver1 outputs the first voltage signal V1 or the second voltage signal V2, the third end of the first driver Driver1 is coupled to the first voltage signal V1, and the fourth end of the first driver Driver1 is coupled to the second voltage signal V2, wherein when the level state of the mode control signal MODE is high (high level), the first voltage signal V1 is output, and when the level state of the mode control signal MODE is low (low level), the second voltage signal V2 is output. Further, the first voltage signal V1 is equal to the input voltage Vin, and the second voltage signal V2 is zero voltage.

[0033] Further, such as Figure 7 As shown, the protection circuit 140 is a voltage stabilizing diode DZ, wherein the positive electrode of the voltage stabilizing diode DZ is coupled to the ground terminal, and the negative electrode of the voltage stabilizing diode DZ is coupled to the second electrode of the first power tube MHS and the second electrode of the first transistor M1 respectively. When the gate voltage of the M1 tube is connected to Vin, and the voltage at point A is equal to Vin+VGS of M1, when the MHS is to be turned on, the gate voltage of the MHS is 0, and the gate-source voltage of the MHS will be relatively large at this time. After adding DZ, the gate-source voltage of the MHS can be protected from exceeding the maximum gate-source voltage. In addition, DZ can also play a protective role when an electrostatic discharge event (ESD event) occurs.

[0034] The embodiment of the present disclosure also provides a switching power supply conversion chip, which includes the voltage conversion circuit 100 compatible with buck and boost described in the above embodiment of the present application. Therefore, the switching power supply conversion chip can be configured as a buck chip or a boost chip according to actual needs, and input and output isolation can be achieved before enabling.

[0035] In summary, the voltage conversion circuit compatible with buck and boost in the embodiment of the present invention can achieve compatibility with boost and buck applications and smooth soft start while ensuring a simple circuit structure and the same phase of input and output. At the same time, the path from input to output is isolated before enabling to suppress surge current.

[0036] Unless the context clearly indicates otherwise, the singular form of the words used herein and in the appended claims includes the plural and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the words "comprise" and "include" are to be interpreted as inclusive rather than exclusive. Likewise, the terms "include" and "or" should be interpreted as inclusive, unless such interpretation is expressly prohibited herein. Where the term "example" is used herein, particularly when it is placed after a group of terms, "example" is merely exemplary and illustrative and should not be considered exclusive or comprehensive.

[0037] Further aspects and scopes of adaptability become apparent from the description provided herein. It should be understood that various aspects of the present disclosure can be implemented individually or in combination with one or more other aspects. It should also be understood that the description and specific embodiments herein are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0038] Several embodiments of the present disclosure are described in detail above, but it is obvious that those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. The protection scope of the present disclosure is defined by the attached claims.

Claims

1. A voltage conversion circuit compatible with step-down and step-up, characterized in that: The voltage conversion circuit includes: a main circuit, a first transistor, a mode control circuit, a voltage loop control circuit, and a protection circuit. The main circuit is configured to receive an input voltage, adjust the output voltage by controlling the charge and discharge of an inductor coupled to the input voltage, and realize the charge and discharge control of the inductor by switching control of a first power tube and a second power tube coupled to the inductor; The mode control circuit is configured to output a first voltage signal when the output voltage is less than the input voltage, and to output a second voltage signal when the output voltage is equal to or greater than the input voltage; The first transistor is coupled between the main circuit and the output voltage, and is configured to use the first voltage signal or the second voltage signal as a control electrode signal of the first transistor, so that the first transistor works in different working states and realizes voltage boost or voltage reduction of the voltage conversion circuit; The voltage loop control circuit is configured to generate a first control signal and a second control signal according to feedback of the output voltage and a reference voltage, and output the first control signal and the second control signal to the main circuit to control the switches of the first power tube and the second power tube respectively, so that the output voltage is stabilized to a target voltage value; The protection circuit is coupled to the first power tube, and is configured to protect the gate-source voltage of the first power tube from exceeding a maximum gate-source voltage.

2. The voltage conversion circuit compatible with step-down and step-up according to claim 1, characterized in that: The mode control circuit includes: a mode control module, a first driver, Wherein, the mode control module is configured to generate a mode control signal according to the magnitude relationship between the output voltage and the input voltage; The first driver is configured to output a corresponding mode voltage according to a level state of the mode control signal, and the mode voltage includes the first voltage signal and the second voltage signal.

3. The voltage conversion circuit compatible with step-down and step-up according to claim 2, characterized in that: The mode control module includes: a first voltage-dividing resistor string, a second voltage-dividing resistor string, a first comparator, and a first inverter. The first voltage-dividing resistor string is coupled to the input voltage and is configured to detect the input voltage and couple the input voltage detection result obtained to the negative input terminal of the first comparator; The second voltage-dividing resistor string is coupled to the output voltage and is configured to detect the output voltage and couple the obtained output voltage detection result to the positive input terminal of the first comparator; The output terminal of the first comparator is coupled to the input terminal of the first inverter, and the output terminal of the first inverter outputs the mode control signal.

4. The voltage conversion circuit compatible with step-down and step-up according to claim 3, characterized in that: The first end of the first driver is coupled to the mode control signal, the second end of the first driver outputs the first voltage signal or the second voltage signal, the third end of the first driver is coupled to the first voltage signal, and the fourth end of the first driver is coupled to the second voltage signal, wherein when the level state of the mode control signal is high, the first voltage signal is output, and when the level state of the mode control signal is low, the second voltage signal is output.

5. The voltage conversion circuit compatible with step-down and step-up according to claim 4, characterized in that: The first transistor is a P-type MOS tube, the first voltage signal is equal to the input voltage, and the second voltage signal is zero voltage.

6. The voltage conversion circuit compatible with step-down and step-up according to claim 5, characterized in that: The main circuit includes the inductor, the first power tube, and the second power tube. One end of the inductor is coupled to the input voltage, and the other end of the inductor is coupled to the first electrode of the first power tube and the first electrode of the second power tube respectively; The second electrode of the first power tube is coupled to the protection circuit and the second electrode of the first transistor respectively, and the control electrode of the first power tube is coupled to the first control signal; The second electrode of the second power tube is coupled to the ground terminal, and the control electrode of the second power tube is coupled to the second control signal.

7. The voltage conversion circuit compatible with step-down and step-up according to claim 6, characterized in that: The voltage loop control circuit includes: a third voltage-dividing resistor string, a current source, a capacitor, an error amplifier, a second comparator, a trigger, a second driver, a third driver, and a second inverter. Wherein, the third voltage-dividing resistor string is respectively coupled to the output voltage and the first input terminal of the error amplifier; One end of the current source is coupled to the power supply voltage, the other end of the current source is respectively coupled to one end of the capacitor and the second input end of the error amplifier, and the other end of the capacitor is coupled to the ground end; The third input terminal of the error amplifier is coupled to a reference voltage, and the output terminal of the error amplifier is coupled to a negative input terminal of the second comparator; The positive input terminal of the second comparator is coupled to the slope compensation signal, and the output terminal of the second comparator is coupled to the reset input terminal of the trigger; The set input terminal of the trigger is coupled to the clock signal, and the output terminal of the trigger is coupled to the input terminal of the second driver and the input terminal of the second inverter respectively; The output terminal of the second driver outputs the second control signal; The output terminal of the second inverter is coupled to the input terminal of the third driver, and the output terminal of the third driver outputs the first control signal.

8. The voltage conversion circuit compatible with step-down and step-up according to claim 5, characterized in that: The protection circuit includes: a voltage regulator diode, wherein the positive electrode of the voltage regulator diode is coupled to the ground terminal, and the negative electrode of the voltage regulator diode is coupled to the second electrode of the first power tube and the second electrode of the first transistor respectively.

9. The voltage conversion circuit compatible with step-down and step-up according to claim 7, wherein the target voltage value corresponding to the step-up or step-down is different, and is characterized in that: The ratio between the resistors in the third voltage-dividing resistor string is adjusted according to the target voltage value.

10. A switching power conversion chip, characterized in that: The switching power supply conversion chip includes a voltage conversion circuit compatible with step-down and step-up as claimed in any one of claims 1 to 9.

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