Step-down step-up converter, control method, chip and electronic device

Abstract

The application provides a buck-boost converter, a control method, a chip and an electronic device. In the case that the buck-boost converter is in a buck mode and a light load mode, a power control circuit controls a third power tube to be always turned off, a fourth power tube to be always turned on, and controls a first power tube and a second power tube to be switched between being turned on and being turned off, so that an inductor is switched between being charged and being discharged. The power control circuit determines whether the current of the inductor when discharging is zero by detecting the voltage drop when the fourth power tube is turned on. When the current of the inductor when discharging is zero, the power control circuit controls the third power tube to be turned on and the fourth power tube to be turned off, so that the voltage across the inductor is zero, and the current of the inductor is maintained as the current when discharging is stopped. Further, when the inductor is charged again, the inductor current gradually increases from the current when discharging is stopped. Thus, the average current of the inductor in each switching period remains unchanged, so that the buck-boost converter tends to be stable.

Description

Technical Field

[0001] This application relates to the field of power management chip technology, and in particular to a buck-boost converter, control method, chip and electronic device. Background Technology

[0002] A buck-boost converter (also known as a peak-valley current converter) is prone to instability when operating in buck mode or light-load mode. This is because the inductor may continue to discharge at a high rate even after it stops discharging during the current switching cycle, leading to a lower average current in the next switching cycle. Buck mode refers to a mode where the input voltage is higher than the output voltage. Light-load mode refers to a mode where the inductor current drops to zero in each switching cycle and then stops decreasing; zero is the moment the inductor current changes from positive to negative. Summary of the Invention

[0003] This application provides a buck-boost converter, a control method, a chip, and an electronic device that can keep the average current of the inductor constant in each switching cycle, thereby stabilizing the buck-boost converter.

[0004] In a first aspect, this application provides a buck-boost converter, the buck-boost converter comprising: a power control circuit, a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, and an inductor;

[0005] The source terminal of the first power transistor is used to connect to the input voltage of the buck-boost converter. The drain terminal of the first power transistor is electrically connected to the first terminal of the inductor. The drain terminal of the second power transistor is electrically connected between the drain terminal of the first power transistor and the first terminal of the inductor. The second terminal of the inductor is electrically connected to the drain terminal of the fourth power transistor. The drain terminal of the third power transistor is electrically connected between the second terminal of the inductor and the drain terminal of the fourth power transistor. The source terminal of the fourth power transistor is used to output the output voltage of the buck-boost converter. The source terminals of the second and third power transistors are both grounded. The first input terminal of the power control circuit is electrically connected to the drain terminal of the fourth power transistor. The second input terminal of the power control circuit is electrically connected to the source terminal of the fourth power transistor. The output terminal of the power control circuit is electrically connected to the gate terminals of the first, second, third, and fourth power transistors, respectively.

[0006] When the buck-boost converter is in buck mode and light load mode, wherein:

[0007] The power control circuit is used to control the third power transistor to always be off and the fourth power transistor to always be on, and to control the first power transistor and the second power transistor to switch between being on or off, so that the inductor switches between charging and discharging.

[0008] The power control circuit is further configured to determine whether the current of the inductor is zero-crossing when it is discharging by detecting the voltage drop when the fourth power transistor is turned on, and when the current of the inductor is zero-crossing when it is discharging, control the third power transistor to turn on and the fourth power transistor to turn off so that the voltage across the inductor is zero, so that the average current of the inductor remains constant in each switching cycle.

[0009] With the buck-boost converter provided in the first aspect, when the buck-boost converter is in buck mode and light load mode, the power control circuit can control the third power transistor to always be off and the fourth power transistor to always be on, and control the first and second power transistors to switch between on and off, so that the inductor switches between charging and discharging. The power control circuit determines whether the inductor current crosses zero point when discharging by detecting the voltage drop when the fourth power transistor is on. When the inductor current crosses zero point when discharging, the power control circuit can control the third power transistor to turn on and the fourth power transistor to turn off, so that the voltage across the inductor is zero, and the inductor current is maintained at the current when discharging stops. Therefore, when the inductor recharges, the inductor current gradually increases from the current when discharging stops. Thus, the average current of the inductor in each switching cycle remains constant, making the buck-boost converter tend to stabilize.

[0010] In one possible design, the power control circuit includes: a feedback module, a differential amplifier, a voltage-to-current module, a clamping module, a current control delay module, a timing module, a logic control module, a first comparator, a second comparator, a first resistor, and a first capacitor.

[0011] The input terminals of the feedback module and the first input terminal of the timing module are both used to connect to the output voltage. The second input terminal of the timing module is used to connect to the input voltage. The output terminal of the timing module is electrically connected to the first input terminal of the logic control module. The output terminal of the feedback module is electrically connected to the negative input terminal of the differential amplifier. The positive input terminal of the differential amplifier is used to connect to the reference voltage. The output terminal of the differential amplifier is electrically connected to the input terminal of the voltage-to-current module. The first output terminal of the voltage-to-current module is electrically connected to the input terminal of the current-controlled delay module. The output terminal of the current-controlled delay module is electrically connected to the second input terminal of the logic control module. The second output terminal of the voltage-to-current module is electrically connected to the input terminal of the clamping module. The output terminal of the clamping module is electrically connected to the negative input terminal of the first comparator. The positive input terminal of the first comparator is used to collect the current when the second power transistor or the third power transistor is turned on. The output terminal of the first comparator is electrically connected to the third input terminal of the logic control module. The positive input terminal of the second comparator is electrically connected to the source terminal of the fourth power transistor. The negative input terminal of the second comparator is electrically connected to the drain terminal of the fourth power transistor. The output terminal of the second comparator is electrically connected to the fourth input terminal of the logic control module. The first terminal of the first resistor is electrically connected between the output terminal of the differential amplifier and the input terminal of the voltage-to-current module. The second terminal of the first resistor is electrically connected to the upper plate of the first capacitor. The lower plate of the first capacitor is grounded.

[0012] The feedback module is used to transmit a feedback voltage to the differential amplifier, and the feedback voltage is used to characterize the change of the output voltage.

[0013] The differential amplifier is used to amplify the voltage difference between the feedback voltage and the reference voltage to obtain a first voltage, and transmit the first voltage to the voltage-to-current module through the first resistor and the first capacitor;

[0014] The voltage-to-current module is used to convert the first voltage into the first current and transmit the first current to the clamping module and the current control delay module, respectively.

[0015] The current control delay module is used to determine whether to change the delay time based on the magnitude of the first current to obtain a first pulse signal, and to transmit the first pulse signal to the logic control module. The first pulse signal is used to determine the switching period.

[0016] The clamping module is used to clamp the first current to obtain a second current and transmit the second current to the first comparator;

[0017] The first comparator is used to compare the current when the second power transistor is turned on with the second current to obtain a second pulse signal, and transmit the second pulse signal to the logic control module. The second pulse signal is used to control the power transistor to turn on or off.

[0018] The timing module is used to obtain a third pulse signal based on the input voltage and the output voltage, and transmit the third pulse signal to the logic control module. The third pulse signal is used to control the on-time of the buck-boost converter in the buck mode.

[0019] The logic control module is used to control the third power transistor to always be off and the fourth power transistor to always be on, based on the first pulse signal, the second pulse signal and the third pulse signal, and to control the first power transistor and the second power transistor to switch between being on or off.

[0020] The second comparator is used to detect the voltage drop when the fourth power transistor is turned on by comparing the source voltage and drain voltage when the fourth power transistor is turned on, and to transmit the zero-crossing signal to the logic control module when the current of the inductor crosses zero during discharge.

[0021] The logic control module is also used to control the third power transistor to turn on and the fourth power transistor to turn off according to the zero-crossing signal.

[0022] In one possible design, the feedback module includes a second resistor and a third resistor;

[0023] The first end of the second resistor is used to connect to the output voltage, the second end of the second resistor is electrically connected to the first end of the third resistor, the negative input terminal of the differential amplifier is electrically connected between the second end of the second resistor and the first end of the third resistor, and the second end of the third resistor is grounded.

[0024] In one possible design, the power control circuit is specifically used to determine the zero-crossing point of the inductor's current during discharge when the voltage drop when the fourth power transistor is turned on is detected to be zero; or, when the voltage drop when the fourth power transistor is turned on is detected to be non-zero, determine that the current of the inductor during discharge has not crossed zero.

[0025] In one possible design, the buck-boost converter further includes an output capacitor and an output resistor;

[0026] The upper plate of the output capacitor and the first terminal of the output resistor are both electrically connected to the source terminal of the fourth power transistor, and the lower plate of the output capacitor and the second terminal of the output resistor are both grounded.

[0027] In one possible design, the second and third power transistors are N-type power transistors, and the first and fourth power transistors are P-type power transistors.

[0028] In a second aspect, this application provides a control method executed by a synchronous rectifier controller in the first aspect and various possible designs of the first aspect, wherein the buck-boost converter includes: a power control circuit, a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, and an inductor;

[0029] The source terminal of the first power transistor is used to connect to the input voltage of the buck-boost converter. The drain terminal of the first power transistor is electrically connected to the first terminal of the inductor. The drain terminal of the second power transistor is electrically connected between the drain terminal of the first power transistor and the first terminal of the inductor. The second terminal of the inductor is electrically connected to the drain terminal of the fourth power transistor. The drain terminal of the third power transistor is electrically connected between the second terminal of the inductor and the drain terminal of the fourth power transistor. The source terminal of the fourth power transistor is used to output the output voltage of the buck-boost converter. The source terminals of the second and third power transistors are both grounded. The first input terminal of the power supply control circuit is electrically connected to the drain terminal of the fourth power transistor. The second input terminal of the power supply control circuit is electrically connected to the source terminal of the fourth power transistor. The output terminal of the power supply control circuit is electrically connected to the gate terminals of the first, second, third, and fourth power transistors, respectively. The method includes:

[0030] When the buck-boost converter is in buck mode and light load mode, wherein:

[0031] The power control circuit controls the third power transistor to always be off and the fourth power transistor to always be on, and controls the first power transistor and the second power transistor to switch between being on or off, so that the inductor switches between charging and discharging.

[0032] The power control circuit determines whether the current of the inductor crosses zero when it discharges by detecting the voltage drop when the fourth power transistor is turned on. When the current of the inductor crosses zero when it discharges, it controls the third power transistor to turn on and the fourth power transistor to turn off, so that the voltage across the inductor is zero, and the average current of the inductor remains constant in each switching cycle.

[0033] The beneficial effects of the methods provided in the second aspect and the various possible designs of the second aspect can be found in the first aspect and the various possible implementations of the first aspect, and will not be repeated here.

[0034] Thirdly, this application provides a chip including: the buck-boost converter in the first aspect and various possible designs of the first aspect.

[0035] Fourthly, this application provides an electronic device, including the chip described in the third aspect above.

[0036] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a timing diagram of a buck-boost converter in related technologies;

[0039] Figure 2 This is a schematic diagram of the current waveform of the inductor in a buck-boost converter in related technologies;

[0040] Figure 3 This is a schematic diagram of a buck-boost converter provided in one embodiment of this application;

[0041] Figure 4 A flowchart illustrating a control method provided in an embodiment of this application;

[0042] Figure 5 This application provides a timing diagram of a buck-boost converter according to an embodiment of the present application.

[0043] Figure 6 This is a schematic diagram of the current waveform of the inductor in a buck-boost converter provided in one embodiment of this application. Detailed Implementation

[0044] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0046] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0047] First, the technical terms involved in the embodiments of this application will be explained.

[0048] Buck mode refers to a buck-boost converter where the input voltage is greater than the output voltage in this mode.

[0049] Boost mode refers to the buck-boost converter where the input voltage is less than the output voltage in this mode.

[0050] Buck-boost mode refers to a buck-boost converter in which the input voltage is close to the output voltage.

[0051] Light load mode refers to the inductor current dropping to zero in each switching cycle and then ceasing to decrease.

[0052] Heavy load mode refers to the mode in which the current in the inductor changes linearly with the load.

[0053] Zero point refers to the moment when the inductor current changes from a positive value to a negative value.

[0054] In light-load mode, the buck-boost converter employs pulse frequency modulation (PFM). PFM is a technique that controls the output signal by adjusting the frequency of a pulse signal.

[0055] In heavy-load mode, the buck-boost converter employs pulse width modulation (PWM). PWM is a technique that controls the output signal by adjusting the duty cycle of a pulse signal.

[0056] A buck-boost converter may include: power transistors A', B', C', D', and inductor IND'. Power transistors A', B', C', and D' are turned on and off alternately in a certain timing sequence, keeping the output voltage of the buck-boost converter constant while transferring energy from the input voltage to the output voltage through inductor IND'.

[0057] When the input voltage is much greater than the output voltage, power transistor D' is always on, power transistor C' is always off, and power transistors A' and B' alternately turn on and off. At this time, the buck-boost converter is in buck mode. In buck mode, the buck-boost converter operates in valley current mode.

[0058] When the input voltage is much lower than the output voltage, power transistor A' is always on, power transistor B' is always off, and power transistors C' and D' alternately turn on and off. At this time, the buck-boost converter is in boost mode. In boost mode, the buck-boost converter operates in peak current mode.

[0059] When the input voltage approaches the output voltage, power transistors A', B', C', and D' alternately turn on and off according to a specific timing sequence. At this time, the buck-boost converter is in buck-boost mode.

[0060] To improve the efficiency of buck-boost converters under light loads, buck-boost converters are typically designed with an automatic light load mode. When the load is heavy, the buck-boost converter operates in continuous conduction mode (CCM). When the load decreases to a certain level, the buck-boost converter automatically enters light load mode.

[0061] In continuous conduction mode, the operating frequency of the buck-boost converter, i.e., the switching cycle, remains constant. The buck-boost converter stabilizes the output voltage by adjusting the duty cycle of the power transistors. In this mode, the inductor current changes linearly with the load.

[0062] In light-load mode, the power stage circuit, consisting of power transistors A', B', C', and D' and inductor IND', maintains a stable output voltage through intermittent operation. In this mode, the inductor current decreases to zero in each switching cycle and then stops decreasing.

[0063] Reference Figure 1 , Figure 1 for Figure 1 This is a timing diagram illustrating the operation of a buck-boost converter in related technologies. For example... Figure 1 As shown, in the buck-boost converter of the related technology, power transistor C' remains off in buck mode. When the signal PWM' is high, power transistors A' and D' are turned on, power transistor B' is turned off, and the inductor charges. When the signal PWM' is low, power transistors B' and D' are turned on, power transistor A' is turned off, and the inductor discharges. When the inductor current crosses zero, the signal ZCD' becomes high, power transistor B' continues to conduct, power transistors A' and D' are turned off, and the inductor stops discharging.

[0064] The delay time of signal T3' being high determines the switching cycle; that is, the next switching cycle is triggered by signal T3'.

[0065] When signal T3' changes from high to low, signal PWM' goes high, causing the buck-boost converter to begin its next switching cycle. Simultaneously, when signal T3' is set high, the buck-boost converter begins its next delay count.

[0066] Reference Figure 2 , Figure 2 This is a schematic diagram of the current waveform of the inductor in a buck-boost converter in related technologies. For example... Figure 2As shown, the buck-boost converter in related technologies requires high accuracy in detecting the zero-crossing of the inductor current. Therefore, when the zero-crossing detection current I_ZAD' is too high, the inductor current will continue to discharge through the parasitic diodes of power transistors B' and D'. Thus, during inductor discharge, the voltage across the inductor is the sum of the output voltage and the voltage drop across the parasitic diode, causing the inductor current to continue discharging at a relatively high slope even when it stops discharging at time t1. Furthermore, since the conduction times of power transistors A' and D' are fixed, i.e., the charging time of the inductor is fixed, the current at the start of charging in the next switching cycle is lower than the current at the start of charging in the previous switching cycle. In other words, the inductor current at time t2 is lower than the inductor current at time t1. Consequently, the average current of the inductor in the next switching cycle is lower than the average current in the previous switching cycle, requiring the buck-boost converter loop to reduce the delay time t1-t2 for signal T3' to be high. This can lead to instability issues in buck-boost converters when entering light-load mode.

[0067] The voltage drop of the parasitic diode is, for example, 0.7V.

[0068] To address the aforementioned issues, this application provides a buck-boost converter, a control method, a chip, and an electronic device.

[0069] The buck-boost converter can be a chip or a circuit module.

[0070] In this application, electronic devices may include, but are not limited to: portable electronic devices, power management systems, automotive electronics, and home appliances.

[0071] Reference Figure 3 , Figure 3 This is a schematic diagram of a buck-boost converter provided in one embodiment of this application. Figure 3 As shown, the buck-boost converter 100 may include: a power control circuit 110, a first power transistor A, a second power transistor B, a third power transistor C, a fourth power transistor D, and an inductor IND.

[0072] The source terminal of the first power transistor A is used to connect to the input voltage VIN of the buck-boost converter 100. The drain terminal of the first power transistor A is electrically connected to the first terminal of the inductor IND. The drain terminal of the second power transistor B is electrically connected between the drain terminal of the first power transistor A and the first terminal of the inductor IND. The second terminal of the inductor IND is electrically connected to the drain terminal of the fourth power transistor D. The drain terminal of the third power transistor C is electrically connected between the second terminal of the inductor IND and the drain terminal of the fourth power transistor D. The source terminal of the fourth power transistor D is used to output the output voltage VOUT of the buck-boost converter 100. The source terminals of the second power transistor B and the third power transistor C are both grounded. The first input terminal of the power control circuit 110 is electrically connected to the drain terminal of the fourth power transistor D. The second input terminal of the power control circuit 110 is electrically connected to the source terminal of the fourth power transistor D. The output terminal of the power control circuit 110 is electrically connected to the gate terminal of the first power transistor A, the gate terminal of the second power transistor B, the gate terminal of the third power transistor C, and the gate terminal of the fourth power transistor D, respectively.

[0073] The power control circuit 110, the first power transistor A, the second power transistor B, the third power transistor C, the fourth power transistor D, and the inductor IND can be set separately or integrated. This application embodiment does not specifically limit this.

[0074] Among them, the first power transistor A, the second power transistor B, the third power transistor C, and the fourth power transistor D may include, but are not limited to, metal-oxide-semiconductor field-effect transistors and gallium nitride transistors.

[0075] Below, refer to Figure 4 , Figure 4 This is a flowchart illustrating a control method provided in one embodiment of this application.

[0076] S101, the power control circuit controls the third power transistor to always be off and the fourth power transistor to always be on, and controls the first power transistor and the second power transistor to switch between being on or off, so that the inductor switches between charging and discharging.

[0077] S102. The power control circuit determines whether the current of the inductor crosses zero when it discharges by detecting the voltage drop when the fourth power transistor is turned on. When the current of the inductor crosses zero when it discharges, it controls the third power transistor to turn on and the fourth power transistor to turn off, so that the voltage across the inductor is zero and the average current of the inductor remains constant in each switching cycle.

[0078] The following is combined with Figure 5 and Figure 6 , Figure 5 This is a timing diagram illustrating the operation of a buck-boost converter according to an embodiment of this application. Figure 6This is a schematic diagram of the current waveform of the inductor in a buck-boost converter according to an embodiment of this application. It details the operation of the buck-boost converter 100 in buck mode and light load mode.

[0079] The power control circuit 110 can control the third power transistor C to always be off and the fourth power transistor D to always be on. Furthermore, the power control circuit 110 can control the first power transistor A and the second power transistor B to switch between on and off states. Figure 5 During the T0-T1 time period, the power control circuit 110 can control the first power transistor A to turn on, the second power transistor B to turn off, and the inductor IND to charge, causing the current IL of the inductor IND to gradually increase. Figure 5 During the T1-T2 time period, the power control circuit 110 can control the first power transistor A to turn off, the second power transistor B to turn on, and the inductor IND to discharge, causing the current IL of the inductor IND to gradually decrease. Figure 5 During the T3-T4 period, the power control circuit 110 can control the first power transistor A to turn on, the second power transistor B to turn off, and the inductor IND to charge, causing the current IL of the inductor IND to gradually increase. Figure 5 During the T4-T5 period, the power control circuit 110 can control the first power transistor A to turn off and the second power transistor B to turn on, causing the inductor IND to discharge and the current IL of the inductor IND to gradually decrease. In this way, the inductor IND switches between charging and discharging.

[0080] The power supply control circuit 110 determines whether the current of the inductor IND during discharge crosses zero by detecting the voltage drop when the fourth power transistor D is turned on. When the voltage drop when the fourth power transistor D is turned on is zero, the power supply control circuit 110 can determine that the current of the inductor IND during discharge crosses zero. When the voltage drop when the fourth power transistor D is turned on is not zero, the power supply control circuit 110 can determine that the current of the inductor IND during discharge has not crossed zero.

[0081] Thus, in Figure 5 At times T2 and T4, when the current of inductor IND crosses zero during discharge, the power supply control circuit 110 can control the third power transistor C to turn on and the fourth power transistor D to turn off, making the voltage across inductor IND zero. This means the current across inductor IND remains constant. In other words, the inductor... Figure 5 The current at time T3 remains at Figure 5 The current when the inductor stops discharging at time T2. Furthermore, the current of the inductor IND in the next switching cycle (i.e., Figure 5 When charging occurs during the T3-T5 period, the current in the inductor IND will also decrease from the point when it stops discharging in the previous switching cycle (i.e., Figure 5 The current gradually increases at time T2. Therefore, as... Figure 6As shown, the average current IL_AVG of the inductor IND remains constant during each switching cycle, causing the buck-boost converter 100 to tend to stabilize.

[0082] In some examples, the second power transistor B and the third power transistor C are N-type power transistors, while the first power transistor A and the fourth power transistor D are P-type power transistors.

[0083] The buck-boost converter provided in this application, when in buck mode and light-load mode, allows the power control circuit to keep the third power transistor always off and the fourth power transistor always on, while controlling the first and second power transistors to switch between on and off, thus switching the inductor between charging and discharging. The power control circuit determines whether the inductor's current crosses zero during discharge by detecting the voltage drop when the fourth power transistor is on. When the inductor's current crosses zero during discharge, the power control circuit can control the third power transistor to turn on and the fourth power transistor to turn off, making the voltage across the inductor zero and maintaining the inductor current at the level when discharging stops. Furthermore, when the inductor recharges, the inductor current gradually increases from the current at the level when discharging stops. Therefore, the average current of the inductor remains constant in each switching cycle, stabilizing the buck-boost converter.

[0084] Based on the description of the above embodiments, an exemplary possible implementation of the power control circuit 110 is provided. For example... Figure 3 As shown, the power control circuit 110 may include: a feedback module 111, a differential amplifier 112, a voltage-to-current conversion module 113, a clamping module 114, a current control delay module 115, a timing module 116, a logic control module 117, a first comparator 118, a second comparator 119, a first resistor R1, and a first capacitor C1.

[0085] The input terminals of feedback module 111 and timing module 116 are both connected to the output voltage VOUT. The second input terminal of timing module 116 is connected to the input voltage VIN. The output terminal of timing module 116 is electrically connected to the first input terminal of logic control module 117. The output terminal of feedback module 111 is electrically connected to the negative input terminal of differential amplifier 112. The positive input terminal of differential amplifier 112 is connected to the reference voltage VREF. The output terminal of differential amplifier 112 is electrically connected to the input terminal of voltage-to-current module 113. The first output terminal of voltage-to-current module 113 is electrically connected to the input terminal of current control delay module 115. The output terminal of current control delay module 115 is electrically connected to the second input terminal of logic control module 117. The second output terminal of voltage-to-current module 113 is connected to clamping module 114. The input terminals are electrically connected. The output terminal of the clamping module 114 is electrically connected to the negative input terminal of the first comparator 118. The positive input terminal of the first comparator 118 is used to collect the current when the second power transistor B or the third power transistor C is turned on. The output terminal of the first comparator 118 is electrically connected to the third input terminal of the logic control module 117. The positive input terminal of the second comparator 119 is electrically connected to the source terminal of the fourth power transistor D. The negative input terminal of the second comparator 119 is electrically connected to the drain terminal of the fourth power transistor D. The output terminal of the second comparator 119 is electrically connected to the fourth input terminal of the logic control module 117. The first terminal of the first resistor R1 is electrically connected between the output terminal of the differential amplifier 112 and the input terminal of the voltage-to-current module 113. The second terminal of the first resistor R1 is electrically connected to the upper plate of the first capacitor C1. The lower plate of the first capacitor C1 is grounded.

[0086] In buck mode (BUCK), the positive input of the first comparator 118 is used to acquire the current when the second power transistor B is turned on. In boost mode (BOOST), the positive input of the first comparator 118 is used to acquire the current when the third power transistor C is turned on.

[0087] In some examples, the feedback module 111 may include a second resistor R2 and a third resistor R3.

[0088] The first end of the second resistor R2 is used to connect the output voltage VOUT. The second end of the second resistor R2 is electrically connected to the first end of the third resistor R3. The negative input terminal of the differential amplifier 112 is electrically connected between the second end of the second resistor R2 and the first end of the third resistor R3. The second end of the third resistor R3 is grounded.

[0089] The feedback module 111 can transmit the feedback voltage VFB to the differential amplifier 112, so that the differential amplifier 112 can obtain the feedback voltage VFB.

[0090] The feedback voltage VFB is used to characterize the change in the output voltage VOUT.

[0091] The differential amplifier 112 can amplify the voltage difference between the feedback voltage VFB and the reference voltage VREF to obtain the first voltage VC. Furthermore, the differential amplifier 112 can transmit the first voltage VC to the voltage-to-current module 113 through the first resistor R1 and the first capacitor C1, so that the voltage-to-current module 113 can obtain the first voltage VC.

[0092] Among them, the first voltage VC decreases as the load decreases.

[0093] The voltage-to-current module 113 can convert the first voltage VC into a first current I1. Furthermore, the voltage-to-current module 113 can transmit the first current I1 to the clamping module 114 and the current control delay module 115 respectively, so that the clamping module 114 and the current control delay module 115 can obtain the first current I1.

[0094] The first current I1 input to the current control delay module 115 can also be represented by the letters IPFM.

[0095] The current-controlled delay module 115 can determine whether to change the delay time based on the magnitude of the first current I1 to obtain the first pulse signal T3. Furthermore, the current-controlled delay module 115 can transmit the first pulse signal T3 to the logic control module 117, so that the logic control module 117 can acquire the first pulse signal T3.

[0096] The first pulse signal T3 is used to determine the switching period.

[0097] The delay time increases as the first current I1, i.e., the first current IPFM, decreases. In light-load mode, the first voltage VC decreases, causing the first current I1 to decrease, which in turn increases the delay time. Consequently, the switching period determined by the first pulse signal T3 is greater than the switching period determined by the first pulse signal T3, making the switching period determined by the first pulse signal T3.

[0098] The clamping module 114 can clamp the first current I1 to obtain the second current IC. Furthermore, the clamping module 114 can transmit the second current IC to the first comparator 118, so that the first comparator 118 can acquire the second current IC.

[0099] Specifically, when the first current I1 is greater than the preset current set by the clamping module 114, the second current IC is equal to the first current I1. When the first current I1 is less than the preset current set by the clamping module 114, the second current IC is equal to the preset current. Because in light-load mode, the first current I1 is clamped to the preset current by the clamping module 114, the second current IC equals the preset current, ensuring that the inductor current stops decreasing after reaching zero in each switching cycle.

[0100] The first comparator 118 can compare the current when the second power transistor B is turned on with the second current IC to obtain the second pulse signal PWM. Furthermore, the first comparator 118 can transmit the second pulse signal PWM to the logic control module 117, so that the logic control module 117 can acquire the second pulse signal PWM.

[0101] The second pulse signal PWM is used to control the power transistor to turn on or off.

[0102] The timing module 116 can monitor the input voltage VIN and the output voltage VOUT to obtain the third pulse signal T1. Furthermore, the timing module 116 can transmit the third pulse signal T1 to the logic control module 117, so that the logic control module 117 can acquire the third pulse signal T1.

[0103] The third pulse signal T1 is used to control the conduction time of the buck-boost converter 100 in buck mode BUCK.

[0104] The timing module 116 monitors the input voltage VIN and output voltage VOUT to obtain a fourth pulse signal T2 for controlling the buck-boost converter 100 in boost mode. Since the fourth pulse signal T2 is inactive in buck mode, it is not used in [the specific context is missing]. Figure 3 This is reflected in the text.

[0105] The logic control module 117 can control the third power transistor C to always be off and the fourth power transistor D to always be on, based on the first pulse signal T3, the second pulse signal PWM and the third pulse signal T1, and control the first power transistor A and the second power transistor B to switch between being on or off.

[0106] The second comparator 119 can detect the voltage drop of the fourth power transistor D when it is turned on by comparing the source voltage and the drain voltage. Furthermore, when the current of the inductor IND crosses zero during discharge, the second comparator 119 can obtain the zero-crossing signal ZCD and transmit it to the logic control module 117, enabling the logic control module 117 to acquire the zero-crossing signal ZCD.

[0107] In this way, the logic control module 117 can control the third power transistor C to turn on and the fourth power transistor D to turn off based on the zero-crossing signal ZCD. Therefore, when the current of the inductor IND crosses zero during discharge, the power supply control circuit 110 can control the third power transistor C to turn on and the fourth power transistor D to turn off. The fourth power transistor D being turned off prevents the current in the inductor IND from becoming negative, while the third power transistor C being turned on makes the voltage across the inductor IND zero.

[0108] Based on the description of the above embodiments, an exemplary possible implementation of the buck-boost converter 100 is provided. Figure 3 As shown, the buck-boost converter 100 may also include an output capacitor Cout and an output resistor Rout.

[0109] The upper plate of the output capacitor Cout and the first terminal of the output resistor Rout are both electrically connected to the source terminal of the fourth power transistor D, and the lower plate of the output capacitor Cout and the second terminal of the output resistor Rout are both grounded.

[0110] Finally, it should be noted that the above embodiments are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A buck-boost converter, characterized in that, The buck-boost converter includes: a power control circuit, a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, and an inductor; The source terminal of the first power transistor is used to connect to the input voltage of the buck-boost converter. The drain terminal of the first power transistor is electrically connected to the first terminal of the inductor. The drain terminal of the second power transistor is electrically connected between the drain terminal of the first power transistor and the first terminal of the inductor. The second terminal of the inductor is electrically connected to the drain terminal of the fourth power transistor. The drain terminal of the third power transistor is electrically connected between the second terminal of the inductor and the drain terminal of the fourth power transistor. The source terminal of the fourth power transistor is used to output the output voltage of the buck-boost converter. The source terminals of the second and third power transistors are both grounded. The first input terminal of the power control circuit is electrically connected to the drain terminal of the fourth power transistor. The second input terminal of the power control circuit is electrically connected to the source terminal of the fourth power transistor. The output terminal of the power control circuit is electrically connected to the gate terminals of the first, second, third, and fourth power transistors, respectively. When the buck-boost converter is in buck mode and light load mode, wherein: The power control circuit is used to control the third power transistor to always be off and the fourth power transistor to always be on, and to control the first power transistor and the second power transistor to switch between being on or off, so that the inductor switches between charging and discharging. The power control circuit is also used to determine whether the current of the inductor is zero when it is discharging by detecting the voltage drop when the fourth power transistor is turned on, and when the current of the inductor is zero when it is discharging, control the third power transistor to turn on and the fourth power transistor to turn off so that the voltage across the inductor is zero, so that the average current of the inductor remains unchanged in each switching cycle. The power control circuit includes: a feedback module, a differential amplifier, a voltage-to-current conversion module, a clamping module, a current control delay module, a timing module, a logic control module, a first comparator, a second comparator, a first resistor, and a first capacitor; The input terminals of the feedback module and the first input terminal of the timing module are both used to connect to the output voltage. The second input terminal of the timing module is used to connect to the input voltage. The output terminal of the timing module is electrically connected to the first input terminal of the logic control module. The output terminal of the feedback module is electrically connected to the negative input terminal of the differential amplifier. The positive input terminal of the differential amplifier is used to connect to the reference voltage. The output terminal of the differential amplifier is electrically connected to the input terminal of the voltage-to-current module. The first output terminal of the voltage-to-current module is electrically connected to the input terminal of the current-controlled delay module. The output terminal of the current-controlled delay module is electrically connected to the second input terminal of the logic control module. The second output terminal of the voltage-to-current module is electrically connected to the input terminal of the clamping module. The output terminal of the clamping module is electrically connected to the negative input terminal of the first comparator. The positive input terminal of the first comparator is used to collect the current when the second power transistor or the third power transistor is turned on. The output terminal of the first comparator is electrically connected to the third input terminal of the logic control module. The positive input terminal of the second comparator is electrically connected to the source terminal of the fourth power transistor. The negative input terminal of the second comparator is electrically connected to the drain terminal of the fourth power transistor. The output terminal of the second comparator is electrically connected to the fourth input terminal of the logic control module. The first terminal of the first resistor is electrically connected between the output terminal of the differential amplifier and the input terminal of the voltage-to-current module. The second terminal of the first resistor is electrically connected to the upper plate of the first capacitor. The lower plate of the first capacitor is grounded. The feedback module is used to transmit a feedback voltage to the differential amplifier, and the feedback voltage is used to characterize the change of the output voltage. The differential amplifier is used to amplify the voltage difference between the feedback voltage and the reference voltage to obtain a first voltage, and transmit the first voltage to the voltage-to-current module through the first resistor and the first capacitor; The voltage-to-current module is used to convert the first voltage into a first current and transmit the first current to the clamping module and the current control delay module, respectively. The current control delay module is used to determine whether to change the delay time based on the magnitude of the first current to obtain a first pulse signal, and to transmit the first pulse signal to the logic control module. The first pulse signal is used to determine the switching period. The clamping module is used to clamp the first current to obtain a second current and transmit the second current to the first comparator; The first comparator is used to compare the current when the second power transistor is turned on with the second current to obtain a second pulse signal, and transmit the second pulse signal to the logic control module. The second pulse signal is used to control the power transistor to turn on or off. The timing module is used to obtain a third pulse signal based on the input voltage and the output voltage, and transmit the third pulse signal to the logic control module. The third pulse signal is used to control the on-time of the buck-boost converter in the buck mode. The logic control module is used to control the third power transistor to always be off and the fourth power transistor to always be on, based on the first pulse signal, the second pulse signal and the third pulse signal, and to control the first power transistor and the second power transistor to switch between being on or off. The second comparator is used to detect the voltage drop when the fourth power transistor is turned on by comparing the source voltage and drain voltage when the fourth power transistor is turned on, and to transmit a zero-crossing signal to the logic control module when the current of the inductor crosses zero during discharge. The logic control module is also used to control the third power transistor to turn on and the fourth power transistor to turn off according to the zero-crossing signal.

2. The buck-boost converter according to claim 1, characterized in that, The feedback module includes: a second resistor and a third resistor; The first end of the second resistor is used to connect to the output voltage, the second end of the second resistor is electrically connected to the first end of the third resistor, the negative input terminal of the differential amplifier is electrically connected between the second end of the second resistor and the first end of the third resistor, and the second end of the third resistor is grounded.

3. The buck-boost converter according to claim 1, characterized in that, The power control circuit is specifically used to determine the zero-crossing point of the current of the inductor during discharge when the voltage drop is detected to be zero when the fourth power transistor is turned on; or, when the voltage drop is detected to be non-zero when the fourth power transistor is turned on, to determine that the current of the inductor during discharge has not crossed zero.

4. The buck-boost converter according to any one of claims 1-3, characterized in that, The buck-boost converter also includes: an output capacitor and an output resistor; The upper plate of the output capacitor and the first terminal of the output resistor are both electrically connected to the source terminal of the fourth power transistor, and the lower plate of the output capacitor and the second terminal of the output resistor are both grounded.

5. The buck-boost converter according to any one of claims 1-3, characterized in that, The second and third power transistors are N-type power transistors, and the first and fourth power transistors are P-type power transistors.

6. A control method, characterized in that, The method is executed by a buck-boost converter, which includes: a power control circuit, a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, and an inductor; The source terminal of the first power transistor is used to connect to the input voltage of the buck-boost converter. The drain terminal of the first power transistor is electrically connected to the first terminal of the inductor. The drain terminal of the second power transistor is electrically connected between the drain terminal of the first power transistor and the first terminal of the inductor. The second terminal of the inductor is electrically connected to the drain terminal of the fourth power transistor. The drain terminal of the third power transistor is electrically connected between the second terminal of the inductor and the drain terminal of the fourth power transistor. The source terminal of the fourth power transistor is used to output the output voltage of the buck-boost converter. The source terminals of the second and third power transistors are both grounded. The first input terminal of the power supply control circuit is electrically connected to the drain terminal of the fourth power transistor. The second input terminal of the power supply control circuit is electrically connected to the source terminal of the fourth power transistor. The output terminal of the power supply control circuit is electrically connected to the gate terminals of the first, second, third, and fourth power transistors, respectively. The method includes: When the buck-boost converter is in buck mode and light load mode, wherein: The power control circuit controls the third power transistor to always be off and the fourth power transistor to always be on, and controls the first power transistor and the second power transistor to switch between being on or off, so that the inductor switches between charging and discharging. The power control circuit determines whether the current of the inductor crosses zero when it discharges by detecting the voltage drop when the fourth power transistor is turned on. When the current of the inductor crosses zero when it discharges, it controls the third power transistor to turn on and the fourth power transistor to turn off, so that the voltage across the inductor is zero and the average current of the inductor remains constant in each switching cycle. The power control circuit includes: a feedback module, a differential amplifier, a voltage-to-current conversion module, a clamping module, a current control delay module, a timing module, a logic control module, a first comparator, a second comparator, a first resistor, and a first capacitor; The input terminals of the feedback module and the first input terminal of the timing module are both used to connect to the output voltage. The second input terminal of the timing module is used to connect to the input voltage. The output terminal of the timing module is electrically connected to the first input terminal of the logic control module. The output terminal of the feedback module is electrically connected to the negative input terminal of the differential amplifier. The positive input terminal of the differential amplifier is used to connect to the reference voltage. The output terminal of the differential amplifier is electrically connected to the input terminal of the voltage-to-current module. The first output terminal of the voltage-to-current module is electrically connected to the input terminal of the current-controlled delay module. The output terminal of the current-controlled delay module is electrically connected to the second input terminal of the logic control module. The second output terminal of the voltage-to-current module is electrically connected to the input terminal of the clamping module. The output terminal of the clamping module is electrically connected to the negative input terminal of the first comparator. The positive input terminal of the first comparator is used to collect the current when the second power transistor or the third power transistor is turned on. The output terminal of the first comparator is electrically connected to the third input terminal of the logic control module. The positive input terminal of the second comparator is electrically connected to the source terminal of the fourth power transistor. The negative input terminal of the second comparator is electrically connected to the drain terminal of the fourth power transistor. The output terminal of the second comparator is electrically connected to the fourth input terminal of the logic control module. The first terminal of the first resistor is electrically connected between the output terminal of the differential amplifier and the input terminal of the voltage-to-current module. The second terminal of the first resistor is electrically connected to the upper plate of the first capacitor. The lower plate of the first capacitor is grounded. The feedback module transmits a feedback voltage to the differential amplifier, and the feedback voltage is used to characterize the change in the output voltage; The differential amplifier amplifies the voltage difference between the feedback voltage and the reference voltage to obtain a first voltage, and transmits the first voltage to the voltage-to-current module through the first resistor and the first capacitor; The voltage-to-current module converts the first voltage into a first current and transmits the first current to the clamping module and the current control delay module, respectively. The current control delay module determines whether to change the delay time based on the magnitude of the first current to obtain a first pulse signal, and transmits the first pulse signal to the logic control module. The first pulse signal is used to determine the switching period. The clamping module clamps the first current to obtain a second current and transmits the second current to the first comparator. The first comparator compares the current when the second power transistor is turned on with the second current to obtain a second pulse signal, and transmits the second pulse signal to the logic control module. The second pulse signal is used to control the power transistor to turn on or off. The timing module obtains a third pulse signal based on the input voltage and the output voltage, and transmits the third pulse signal to the logic control module. The third pulse signal is used to control the on-time of the buck-boost converter in the buck mode. The logic control module controls the third power transistor to always be off and the fourth power transistor to always be on, based on the first pulse signal, the second pulse signal and the third pulse signal, and controls the first power transistor and the second power transistor to switch between being on or off. The second comparator detects the voltage drop when the fourth power transistor is turned on by comparing the source voltage and drain voltage when the fourth power transistor is turned on, and transmits a zero-crossing signal to the logic control module when the current of the inductor crosses zero during discharge. The logic control module controls the third power transistor to turn on and the fourth power transistor to turn off based on the zero-crossing signal.

7. A chip, characterized in that, include: The buck-boost converter as described in any one of claims 1-5.

8. An electronic device, characterized in that, include: The chip as described in claim 7.

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