Precharge circuit, boost converter and electronic device

Abstract

The present application relates to the field of switching power supplies and provides a pre-charge circuit, a boost converter, and an electronic device. The circuit includes a pre-charge current module, a first selection module, a second selection module, and a comparison module. The first selection module is respectively connected to the output end of the pre-charge current module and the gate of the freewheeling diode in the boost converter circuit, and the second selection module is respectively connected to the comparison module and the substrate of the freewheeling diode. The present application does not require the use of an isolation tube, and still achieves the pre-charge function of the boost converter circuit. It also provides isolation protection, reduces the inrush current of the output voltage at startup, reduces output voltage overshoot, and improves the reliability and safety of the boost converter circuit. After removing the isolation tube, no additional drive signal is required, which not only reduces the design complexity of the boost converter circuit, but also reduces the area and cost of the boost converter circuit. At the same time, by eliminating the conduction loss of the isolation tube itself, the problems of reduced conversion efficiency and increased heat generation in the boost converter circuit are avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of switching power supplies, and in particular relates to a pre-charging circuit, a boost converter, and an electronic device. Background Art

[0002] Boost converters are widely used in consumer electronics, intelligent vehicle control, and industrial drives due to their high conversion efficiency and wide voltage range. To limit inrush current and prevent output voltage overshoot, boost converters typically incorporate a pre-charge process during soft-start. This involves charging the output capacitor with a controllable current, slowly bringing the output voltage up to the input voltage. When the output voltage approaches the input voltage, the main switch in the boost converter begins operating, entering normal boost mode.

[0003] Current pre-charge circuits typically utilize an isolation transistor. During the pre-charge phase of a Boost converter, the output voltage is lower than the input voltage. Because the isolation transistor and the freewheeling diode in the Boost converter are connected back-to-back, their body diodes face opposite directions, preventing a current path between the output and input via the body diodes. This prevents the excess conduction losses caused by the freewheeling diode's forward conduction and prevents overheating and failure of the freewheeling diode. However, because both the isolation transistor and the freewheeling diode must carry high currents, the isolation transistor typically requires a large area, essentially the same as the freewheeling diode, and requires an additional drive signal. This not only increases the design complexity and cost of the Boost converter, but also reduces the efficiency and increases heat generation of the Boost converter due to the conduction losses of the isolation transistor. Summary of the Invention

[0004] The embodiments of the present application provide a pre-charging circuit, a boost converter, and an electronic device, which can solve the problems of the current pre-charging circuit implemented using an isolation tube, which leads to complex Boost converter design, increased cost, reduced conversion efficiency, and increased heat generation.

[0005] In a first aspect, an embodiment of the present application provides a pre-charge circuit, comprising a pre-charge current module, a first selection module, a second selection module, and a comparison module, wherein the first selection module is respectively connected to the output end of the pre-charge current module and the gate of a freewheeling tube in a boost conversion circuit, and the second selection module is respectively connected to the comparison module and the substrate of the freewheeling tube;

[0006] In the pre-charging stage of the boost conversion circuit, the pre-charging current module is used to receive the output voltage of the boost conversion circuit and provide a pre-charging current according to the output voltage; the first selection module is used to receive a pre-charging signal and a driving signal, and connect the output end of the pre-charging current module to the gate of the freewheeling tube according to the pre-charging signal, thereby mirroring the pre-charging current to the freewheeling tube; the comparison module is used to receive the output voltage and the input voltage of the boost conversion circuit, compare the output voltage and the input voltage, and output a first signal and a second signal; the second selection module is used to receive the input voltage and the output voltage, and transmit the input voltage to the substrate of the freewheeling tube according to the first signal and the second signal.

[0007] In a possible implementation of the first aspect, after the pre-charging stage of the boost conversion circuit ends, the first selection module is further used to transmit the drive signal to the gate of the freewheeling tube according to the pre-charging signal; the comparison module is further used to compare the output voltage and the input voltage, and output a third signal and a fourth signal; the second selection module is further used to transmit the output voltage to the substrate of the freewheeling tube according to the third signal and the fourth signal.

[0008] In a possible implementation of the first aspect, the comparison module includes a comparison unit and a logic unit, and the logic unit is connected to the comparison unit and the second selection module respectively;

[0009] In the pre-charging phase of the boost converter circuit, the comparison unit is configured to receive the input voltage and the output voltage, and compare the output voltage with the input voltage to obtain a first comparison signal; and the logic unit is configured to output a first signal and a second signal according to the first comparison signal.

[0010] After the pre-charging phase of the boost converter circuit ends, the comparison unit is further configured to compare the output voltage with the input voltage to obtain a second comparison signal; and the logic unit is further configured to output a third signal and a fourth signal according to the second comparison signal.

[0011] In a possible implementation of the first aspect, the comparison unit includes a first resistor, a second resistor, a third resistor, a fourth resistor and a comparator, the first end of the first resistor is used to receive the input voltage, the second end of the first resistor is respectively connected to the first end of the second resistor and the first input end of the comparator, the first end of the third resistor is used to receive the output voltage, the second end of the third resistor is respectively connected to the first end of the fourth resistor and the second input end of the comparator, the output end of the comparator is connected to the logic unit, and the second end of the second resistor and the second end of the fourth resistor are both grounded.

[0012] In a possible implementation of the first aspect, the logic unit includes a first inverter and a second inverter, the input end of the first inverter is connected to the comparison unit, the output end of the first inverter is respectively connected to the input end of the second inverter and the second selection module, and the output end of the second inverter is connected to the second selection module.

[0013] In a possible implementation of the first aspect, the second selection module includes a first switching tube and a second switching tube, the control end of the first switching tube is connected to the comparison module, the first conductive end of the first switching tube is respectively connected to the first conductive end of the second switching tube and the substrate of the freewheeling tube, the second conductive end of the first switching tube is used to receive the input voltage, the control end of the second switching tube is connected to the comparison module, and the second conductive end of the second switching tube is used to receive the output voltage.

[0014] In a possible implementation of the first aspect, the pre-charge current module includes a third switch tube and a current source, the first conduction end of the third switch tube receives the output voltage, the control end of the third switch tube is respectively connected to the second conduction end of the third switch tube, the first end of the current source and the first selection module, and the second end of the current source is grounded.

[0015] In a possible implementation of the first aspect, the first selection module includes a data selector, a first data input end of the data selector is connected to the output end of the pre-charge current module, a second data input end of the data selector is used to receive the drive signal, a control end of the data selector is used to receive the pre-charge signal, and an output end of the data selector is used to be connected to the gate of the freewheeling tube.

[0016] In a second aspect, an embodiment of the present application provides a boost converter comprising the pre-charging circuit described in any one of the first aspects.

[0017] In a third aspect, an embodiment of the present application provides an electronic device comprising the boost converter described in any one of the second aspects.

[0018] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0019] An embodiment of the present application provides a pre-charging circuit, including a pre-charging current module, a first selection module, a second selection module and a comparison module, wherein the first selection module is respectively connected to the output end of the pre-charging current module and the gate of the freewheeling tube in the boost conversion circuit, and the second selection module is respectively connected to the comparison module and the substrate of the freewheeling tube.

[0020] In the pre-charging stage of the boost conversion circuit, the pre-charging current module is used to receive the output voltage of the boost conversion circuit and provide a pre-charging current according to the output voltage; the first selection module is used to receive the pre-charging signal and the driving signal, and connect the output end of the pre-charging current module to the gate of the freewheeling tube according to the pre-charging signal, and then mirror the pre-charging current to the freewheeling tube to charge the output capacitor in the boost conversion circuit, so that the output voltage gradually rises to the input voltage, thereby realizing the pre-charging function; the comparison module is used to receive the output voltage and the input voltage of the boost conversion circuit, and compare the output voltage with the input voltage, and output a first signal and a second signal; the second selection module is used to receive the input voltage and the output voltage, and transmit the input voltage to the substrate of the freewheeling tube according to the first signal and the second signal, and the substrate potential of the freewheeling tube is the input voltage. Since the source voltage of the freewheeling tube is the output voltage and the drain voltage of the freewheeling tube is the input voltage, the potential of the drain and substrate of the freewheeling tube are equal, and the body diode from the drain to the substrate will not be turned on. There is only a body diode from the source to the substrate. In the pre-charging stage, the output voltage is always lower than the input voltage, that is, the potential of the substrate is higher than the potential of the source, so the body diode from the source to the substrate will not be turned on. Therefore, no current path from the input voltage to the output voltage is formed, which plays a role in isolation protection. The present application changes the substrate potential of the freewheeling tube by using a comparison module and a second selection module, cutting off the current path through the body diode of the freewheeling tube. The area of ​​the comparison module and the second selection module is much smaller than that of the isolation tube.

[0021] In summary, this application achieves the pre-charging function of the boost converter circuit without the need for an isolation tube, while also providing isolation protection. This reduces the inrush current of the output voltage at startup, minimizes output voltage overshoot, and improves the reliability and safety of the boost converter circuit. Removing the isolation tube eliminates the need for an additional drive signal, reducing the design complexity, area, and cost of the boost converter circuit. Furthermore, by eliminating the conduction loss of the isolation tube itself, the problems of decreased conversion efficiency and increased heat generation in the boost converter circuit are avoided.

[0022] It can be understood that the beneficial effects of the second to third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 This is a circuit diagram of a pre-charging circuit with an isolation tube;

[0025] Figure 2 This is a principle block diagram of a pre-charging circuit provided in one embodiment of the present application;

[0026] Figure 3 is a principle block diagram of a pre-charging circuit provided in another embodiment of the present application;

[0027] Figure 4 1 is a circuit connection diagram of a pre-charging circuit provided in one embodiment of the present application.

[0028] In the figure: 10, pre-charge current module; 20, first selection module; 30, second selection module; 40, comparison module; 41, comparison unit; 42, logic unit. DETAILED DESCRIPTION

[0029] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0030] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0031] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0032] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0033] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0034] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0035] When the Boost converter is in the pre-charge stage and the pre-pre-charge stage, the output voltage V OUT Less than the input voltage V IN In order to prevent the body diode of the freewheeling tube from forward conduction, an isolation tube is usually required to avoid additional conduction loss and prevent the freewheeling tube from overheating and failure. The isolation tube can also prevent reverse current, such as when the output voltage V OUT When stable, the input voltage V IN Suddenly drop, the body diode of the freewheeling tube reverse conducts, the output capacitor C OUT The energy on the power supply will flow back into the power supply, which may cause overheating and damage to the power supply.

[0036] Figure 1 This is a schematic diagram of a pre-charge circuit with an isolation tube, where MP2 is an isolation tube, MP1 is a freewheeling tube, and MN1 is the main switch tube. In the pre-charge stage, both the main switch tube MN1 and the freewheeling tube MP1 are turned off, and the input voltage V IN The voltage at the SWI point is charged to the input voltage V through the body diode of the freewheeling tube MP1. INAt this time, the PRE_END signal is low, and the fixed bias current I_PRE is mirrored to the isolation tube MP2 branch to the output capacitor C OUT Charging, so that the output voltage V OUT Gradually increases to the input voltage V IN Then, after the pre-charge phase is completed, the PRE_END signal becomes high, MP4 is turned off, and the resistor R1 is a resistor with a resistance of MΩ, so the current flowing through MP3 is very small. The gate voltage of the isolation tube MP2 is pulled down by the bias current I_PRE, making the isolation tube MP2 normally open. When the drive signal P of the freewheeling tube MP1 is DRV When it starts to oscillate, the system enters normal boost mode.

[0037] Because the isolation transistor MP2 and the freewheeling transistor MP1 are connected back-to-back, their body diodes point in opposite directions, preventing a current path between the output and input via the body diodes. This prevents the freewheeling transistor's body diode from conducting forward, leading to additional conduction losses, overheating failure of the freewheeling transistor, and damage to the power supply due to overheating. However, because both the isolation transistor MP2 and the freewheeling transistor MP1 must carry large currents, the isolation transistor MP2 is typically very large, roughly the same size as the freewheeling transistor MP1, and requires an additional drive signal. This not only increases the design complexity and cost of the Boost converter, but also reduces the conversion efficiency and increases heat generation due to the conduction losses of the isolation transistor MP2.

[0038] In view of the above problems, the present invention provides a pre-charging circuit. Figure 2 As shown, the pre-charge circuit includes a pre-charge current module 10, a first selection module 20, a second selection module 30 and a comparison module 40. The first selection module 20 is respectively connected to the output end of the pre-charge current module 10 and the gate of the freewheeling tube MP1 in the boost conversion circuit, and the second selection module 30 is respectively connected to the comparison module 40 and the substrate of the freewheeling tube MP1.

[0039] Specifically, in the pre-charging stage of the boost converter circuit, the pre-charging current module 10 is used to receive the output voltage V OUT , and according to the output voltage V OUT Provide pre-charge current; the first selection module 20 is used to receive the pre-charge signal PRE_END and the drive signal P DRV , and connect the output end of the pre-charge current module 10 to the gate of the freewheeling tube MP1 according to the pre-charge signal PRE_END, and then mirror the pre-charge current to the freewheeling tube MP1, which is the output capacitor C in the boost conversion circuit. OUT Charging (the current path is the input voltage V IN Through the freewheeling tube MP1 to the output capacitor C OUT ), so that the output voltage VOUT Gradually increases to the input voltage V IN , realizing the pre-charging function; it should be noted that the pre-charging signal PRE_END is a signal indicating that the pre-charging is completed, which is low level in the pre-charging stage and high level after the pre-charging stage is completed. The comparison module 40 is used to receive the output voltage V OUT and the input voltage V of the boost converter circuit IN , and the output voltage V OUT and input voltage V IN Compare and output the first signal and the second signal; the second selection module 30 is used to receive the input voltage V IN and the output voltage V OUT , and according to the first signal and the second signal, the input voltage V IN Transmitted to the substrate of the freewheeling tube MP1, the substrate potential of the freewheeling tube MP1 is the input voltage V IN Since the source voltage of the freewheeling tube MP1 is the output voltage V OUT , the drain voltage of the freewheeling tube MP1 is the input voltage V IN , then the potential of the drain and substrate of the freewheeling tube MP1 is equal, then the body diode from the drain to the substrate will not be turned on, and only the body diode from the source to the substrate exists. In the pre-charge stage, the output voltage V OUT Always less than the input voltage V IN , that is, the potential of the substrate is greater than the potential of the source, so the body diode from the source to the substrate will not be turned on. Therefore, no voltage difference from the input voltage V IN To the output voltage V OUT The current path is blocked, which plays an isolation and protection role. The present application changes the substrate potential of the freewheeling tube MP1 through the comparison module and the second selection module, cutting off the current path through the body diode of the freewheeling tube MP1. The area of ​​the comparison module 40 and the second selection module 30 is much smaller than that of the isolation tube.

[0040] In summary, the present application does not need to use an isolation tube, and also realizes the pre-charging function of the boost conversion circuit, while playing an isolation protection role and reducing the output voltage V OUT The inrush current at startup reduces the output voltage V OUT Overshoot improves the reliability and safety of the boost converter circuit. Removing the isolation tube eliminates the need for an additional drive signal, reducing the design complexity, area, and cost of the boost converter circuit. Furthermore, eliminating the conduction loss of the isolation tube itself avoids the problems of reduced conversion efficiency and increased heat generation in the boost converter circuit.

[0041] It should be noted that when the boost converter circuit is in the pre-charge stage, the output voltage V OUT Less than the input voltage V INAt this time, the comparison module 40 still outputs the first signal and the second signal; the second selection module 30 still selects the input voltage V according to the first signal and the second signal. IN Transmitted to the substrate of the freewheeling tube MP1, the substrate potential of the freewheeling tube MP1 is the input voltage V IN Since the source voltage of the freewheeling tube MP1 is the output voltage V OUT , the drain voltage of the freewheeling tube MP1 is the input voltage V IN , then the potential of the drain and substrate of the freewheeling tube MP1 is equal, and the body diode from the drain to the substrate will not be turned on; there is only a body diode from the source to the substrate. In the pre-charge stage, the output voltage V OUT Less than the input voltage V IN , that is, the potential of the substrate is greater than the potential of the source, so the body diode from the source to the substrate will not be turned on. Therefore, when the boost converter circuit is in the pre-charge stage, no voltage drop from the input voltage V IN To the output voltage V OUT The current path also plays the role of isolation protection.

[0042] In some embodiments, after the pre-charging phase of the boost converter circuit ends, the first selection module 20 is further configured to set the drive signal P to DRV The voltage is transmitted to the gate of the freewheeling tube MP1, and the boost conversion circuit enters the normal boost mode; the comparison module 40 is also used to compare the output voltage V OUT and input voltage V IN The second selection module 30 is further configured to output the output voltage V according to the third signal and the fourth signal. OUT is transmitted to the substrate of the freewheeling tube MP1, then the substrate potential of the freewheeling tube MP1 is the output voltage V OUT Since the source voltage of the freewheeling tube MP1 is the output voltage V OUT , the drain voltage of the freewheeling tube MP1 is the input voltage V IN , then the potential of the source and substrate of the freewheeling tube MP1 is equal, then the body diode from the source to the substrate will not be turned on, and only the body diode from the drain to the substrate will exist. After the pre-charge stage is over, the output voltage V OUT Greater than the input voltage V IN , that is, the potential of the substrate is greater than the potential of the drain, so the body diode from the drain to the substrate will not be turned on. Therefore, after the pre-charge stage is over, no voltage drop from the input voltage V IN To the output voltage V OUT The current path also plays the role of isolation protection. It should be noted that when the output voltage V OUT When stable, if the input voltage V INSuddenly drops, the substrate potential of the freewheeling tube MP1 is still the output voltage V OUT , then the body diode from the source to the substrate and the body diode from the drain to the substrate will not be turned on, and no voltage difference from the input voltage V IN To the output voltage V OUT current path to prevent current backflow.

[0043] In some embodiments, as Figure 3 As shown, the comparison module 40 includes a comparison unit 41 and a logic unit 42 , and the logic unit 42 is connected to the comparison unit 41 and the second selection module 30 respectively.

[0044] Specifically, in the pre-charging stage of the boost converter circuit, the comparison unit 41 is used to receive the input voltage V IN and the output voltage V OUT , and the output voltage V OUT and input voltage V IN The logic unit 42 is used to output a first signal and a second signal according to the first comparison signal, wherein the first signal is a high level and the second signal is a low level.

[0045] After the pre-charge phase of the boost converter circuit is completed, the comparison unit 41 is further used to compare the output voltage V OUT and input voltage V IN The comparison is performed to obtain a second comparison signal, which is a high level. The logic unit 42 is further configured to output a third signal and a fourth signal according to the second comparison signal, wherein the third signal is a low level and the fourth signal is a high level.

[0046] In some embodiments, as Figure 4 As shown, the comparison unit 41 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a comparator CMP. The first end of the first resistor R1 is used to receive the input voltage V IN The second end of the first resistor R1 is connected to the first end of the second resistor R2 and the first input end of the comparator CMP respectively. In the embodiment of the present application, the first input end of the comparator CMP is the inverting input end of the comparator CMP. The first end of the third resistor R3 is used to receive the output voltage V OUT The second end of the third resistor R3 is connected to the first end of the fourth resistor R4 and the second input end of the comparator CMP respectively. In the embodiment of the present application, the second input end of the comparator CMP is the positive input end of the comparator CMP. The output end of the comparator CMP is connected to the logic unit 42. The second end of the second resistor R2 and the second end of the fourth resistor R4 are both grounded. The comparator CMP is a low-voltage comparator, so it is necessary to respectively connect the input voltage V IN and the output voltage V OUTVoltage division is performed, but it is necessary to ensure that the ratio of the resistance value of the first resistor R1 to the resistance value of the second resistor R2 is equal to the ratio of the resistance value of the third resistor R3 to the resistance value of the fourth resistor R4.

[0047] Specifically, in the pre-charge phase of the boost converter circuit, the comparator CMP is used to check the output voltage V OUT and input voltage V IN Compare and get the first comparison signal. In the pre-charge stage, the output voltage V OUT Always less than the input voltage V IN , so the first comparison signal is low level.

[0048] After the pre-charge phase of the boost converter circuit is completed, the comparator CMP checks the output voltage V OUT and input voltage V IN After the pre-charge phase is completed, the output voltage V OUT Greater than the input voltage V IN , so the second comparison signal is high level.

[0049] In some embodiments, as Figure 4 As shown, the logic unit 42 includes a first inverter INV1 and a second inverter INV2. The input end of the first inverter INV1 is connected to the comparison unit 41, the output end of the first inverter INV1 is connected to the input end of the second inverter INV2 and the second selection module 30, respectively, and the output end of the second inverter INV2 is connected to the second selection module 30. The first inverter INV1 and the second inverter INV2 are both low-voltage devices.

[0050] Specifically, in the pre-charge phase of the boost converter circuit, the comparator CMP is used to check the output voltage V OUT and input voltage V IN Compare and get the first comparison signal. In the pre-charge stage, the output voltage V OUT Always less than the input voltage V IN , so the first comparison signal is at a low level. The first inverter INV1 inverts the first comparison signal and outputs a first signal at a high level to the input terminal of the second inverter INV2 and the second selection module 30, respectively. The second inverter INV2 inverts the first signal and outputs a second signal at a low level to the second selection module 30.

[0051] After the pre-charge phase of the boost converter circuit is completed, the comparator CMP checks the output voltage V OUT and input voltage V IN After the pre-charge phase is completed, the output voltage V OUT Greater than the input voltage V IN, so the second comparison signal is at a high level. The first inverter INV1 inverts the second comparison signal and outputs a third signal at a low level to the input terminal of the second inverter INV2 and the second selection module 30, respectively. The second inverter INV2 inverts the third signal and outputs a fourth signal at a high level to the second selection module 30.

[0052] In some embodiments, as Figure 4 As shown, the second selection module 30 includes a first switch tube M1 and a second switch tube M2. The control end of the first switch tube M1 is connected to the comparison module 40. The first conduction end of the first switch tube M1 is connected to the first conduction end of the second switch tube M2 and the substrate of the freewheeling tube MP1 respectively. The second conduction end of the first switch tube M1 is used to receive the input voltage V IN The control terminal of the second switch tube M2 is connected to the comparison module 40, and the second conduction terminal of the second switch tube M2 is used to receive the output voltage V OUT In this application, the control terminal of the switch tube is the gate of a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor), the first conductive terminal of the switch tube is the source of the MOS tube, and the second conductive terminal of the switch tube is the drain of the MOS tube. In the embodiment of this application, the first switch tube M1 and the second switch tube M2 are both PMOS (positive channel Metal Oxide Semiconductor) tubes.

[0053] Specifically, in the pre-charge phase of the boost converter circuit, the comparator CMP is used to check the output voltage V OUT and input voltage V IN Compare and get the first comparison signal. In the pre-charge stage, the output voltage V OUT Always less than the input voltage V IN , so the first comparison signal is low. After the first inverter INV1 inverts the first comparison signal, it outputs the first signal to the input end of the second inverter INV2 and the second selection module 30 respectively. If the first signal is high, the second switch tube M2 is turned off. After the second inverter INV2 inverts the first signal, it outputs the second signal to the second selection module 30. If the second signal is low, the first switch tube M1 is turned on. In the pre-charging stage of the boost converter circuit, the second switch tube M2 is turned off and the first switch tube M1 is turned on, which converts the input voltage V IN Transmitted to the substrate of the freewheeling tube MP1, the substrate potential of the freewheeling tube MP1 is the input voltage V IN Since the source voltage of the freewheeling tube MP1 is the output voltage V OUT, the drain voltage of the freewheeling tube MP1 is the input voltage V IN , then the potential of the drain and substrate of the freewheeling tube MP1 is equal, then the body diode from the drain to the substrate will not be turned on, and only the body diode from the source to the substrate exists. In the pre-charge stage, the output voltage V OUT Always less than the input voltage V IN , that is, the potential of the substrate is greater than the potential of the source, so the body diode from the source to the substrate will not be turned on. Therefore, no voltage difference from the input voltage V IN To the output voltage V OUT The current path plays a role of isolation protection.

[0054] After the pre-charge phase of the boost converter circuit is completed, the comparator CMP checks the output voltage V OUT and input voltage V IN After the pre-charge phase is completed, the output voltage V OUT Greater than the input voltage V IN , so the second comparison signal is high. After the first inverter INV1 inverts the second comparison signal, it outputs a third signal to the input terminal of the second inverter INV2 and the second selection module 30 respectively. The third signal is low, and the second switch tube M2 is turned on. After the second inverter INV2 inverts the third signal, it outputs a fourth signal to the second selection module 30. The fourth signal is high, and the first switch tube M1 is turned off. After the pre-charging stage of the boost converter circuit is completed, the first switch tube M1 is turned off and the second switch tube M2 is turned on, and the output voltage V OUT is transmitted to the substrate of the freewheeling tube MP1, then the substrate potential of the freewheeling tube MP1 is the output voltage V OUT Since the source voltage of the freewheeling tube MP1 is the output voltage V OUT , the drain voltage of the freewheeling tube MP1 is the input voltage V IN , then the potential of the source and substrate of the freewheeling tube MP1 is equal, then the body diode from the source to the substrate will not be turned on, and only the body diode from the drain to the substrate will exist. After the pre-charge stage is over, the output voltage V OUT Greater than the input voltage V IN , that is, the potential of the substrate is greater than the potential of the drain, so the body diode from the drain to the substrate will not be turned on. Therefore, after the pre-charge stage is over, no voltage drop from the input voltage V IN To the output voltage V OUT The current path also plays the role of isolation protection.

[0055] In some embodiments, as Figure 4 As shown, the pre-charge current module 10 includes a third switch tube M3 and a current source, and the first conduction terminal of the third switch tube M3 receives the output voltage V OUTThe control terminal of the third switch tube M3 is respectively connected to the second conduction terminal of the third switch tube M3, the first terminal of the current source, and the first selection module 20. The second terminal of the current source is grounded. In the embodiment of the present application, the third switch tube M3 is a PMOS tube.

[0056] Specifically, the current source is used to provide a fixed bias current I_PRE. In the pre-charging stage of the boost converter circuit, the pre-charging signal PRE_END is at a low level, and the first selection module 20 connects the gate of the third switch tube M3 to the gate of the freewheeling tube MP1, thereby mirroring the bias current I_PRE to the freewheeling tube MP1, which is the output capacitor C OUT Charge, so that the output voltage V OUT Gradually increases to the input voltage V IN , realizing the pre-charging function.

[0057] After the pre-charging stage is over, the pre-charging signal PRE_END is at a high level, and the first selection module 20 drives the signal P DRV The voltage is transmitted to the gate of the freewheeling tube MP1, and the boost conversion circuit enters the normal boost mode.

[0058] In some embodiments, as Figure 4 As shown, the first selection module 20 includes a data selector, a first data input terminal of the data selector is connected to the output terminal of the pre-charge current module 10, and a second data input terminal of the data selector is used to receive the driving signal P DRV The control end of the data selector is used to receive the pre-charge signal PRE_END, and the output end of the data selector is used to be connected to the gate of the freewheeling tube MP1.

[0059] Specifically, in the pre-charging stage of the boost converter circuit, the pre-charging signal PRE_END is at a low level, and the data selector connects the gate of the third switch tube M3 to the gate of the freewheeling tube MP1, thereby mirroring the bias current I_PRE to the freewheeling tube MP1, which is the output capacitor C OUT Charge, so that the output voltage V OUT Gradually increases to the input voltage V IN , realizing the pre-charging function.

[0060] After the pre-charge phase is over, the pre-charge signal PRE_END is high, and the data selector drives the signal P DRV The voltage is transmitted to the gate of the freewheeling tube MP1, and the boost conversion circuit enters the normal boost mode.

[0061] In summary, the present application does not require the use of an isolation tube, and also achieves the same effect as the pre-charging circuit with an isolation tube, saving chip area and reducing conduction loss, which can reduce the cost of the chip and improve the efficiency of the system to a certain extent. The present application switches the substrate potential of the freewheeling tube MP1 by using a comparison module 40 and a second selection module 30 composed of low-voltage devices to change the forward conduction direction of the body diode of the freewheeling tube MP1, thereby cutting off the current path through the body diode of the freewheeling tube MP1. When in the pre-charging stage, the output capacitor C is supplied by the freewheeling tube MP1. OUT It is charged with a fixed bias current I_PRE. At this time, the output voltage V OUT Less than the input voltage V IN , the second selection module 30 inputs the voltage V IN Transmitted to the substrate of the freewheeling tube MP1, that is, the substrate potential of the freewheeling tube MP1 is the input voltage V IN , the forward conduction direction of the body diode is from source to drain, and the body diode will not conduct; when the pre-charge is completed, the output voltage V OUT Greater than the input voltage V IN , the second selection module 30 outputs the voltage V OUT The first selection module 20 transmits the driving signal P to the substrate of the freewheeling tube MP1. The forward conduction direction of the freewheeling tube MP1 body diode is from the drain to the source, and the body diode will not be turned on. DRV The voltage is transmitted to the gate of the freewheeling tube MP1, and the boost conversion circuit enters the normal boost stage.

[0062] The present application also provides a boost converter including the pre-charging circuit described above. Since the boost converter provided by the present application includes the pre-charging circuit described above, the boost converter provided by the present application has the advantages of simple design, small area, low cost, and high conversion efficiency.

[0063] The present application also provides an electronic device including the boost converter described above. Since the electronic device circuit provided in the present application adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be detailed here.

[0064] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0065] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A pre-charging circuit, characterized in that: It includes a pre-charge current module, a first selection module, a second selection module and a comparison module, wherein the first selection module is respectively connected to the output end of the pre-charge current module and the gate of the freewheeling tube in the boost conversion circuit, and the second selection module is respectively connected to the comparison module and the substrate of the freewheeling tube; In the pre-charging stage of the boost conversion circuit, the pre-charging current module is used to receive the output voltage of the boost conversion circuit and provide a pre-charging current according to the output voltage; the first selection module is used to receive a pre-charging signal and a driving signal, and connect the output end of the pre-charging current module to the gate of the freewheeling tube according to the pre-charging signal, thereby mirroring the pre-charging current to the freewheeling tube; the comparison module is used to receive the output voltage and the input voltage of the boost conversion circuit, compare the output voltage and the input voltage, and output a first signal and a second signal; the second selection module is used to receive the input voltage and the output voltage, and transmit the input voltage to the substrate of the freewheeling tube according to the first signal and the second signal.

2. The precharge circuit according to claim 1, wherein After the pre-charging stage of the boost conversion circuit ends, the first selection module is further used to transmit the drive signal to the gate of the freewheeling tube according to the pre-charging signal; the comparison module is further used to compare the output voltage and the input voltage and output a third signal and a fourth signal; the second selection module is further used to transmit the output voltage to the substrate of the freewheeling tube according to the third signal and the fourth signal.

3. The precharge circuit according to claim 1 or 2, wherein The comparison module includes a comparison unit and a logic unit, and the logic unit is connected to the comparison unit and the second selection module respectively; In the pre-charging phase of the boost converter circuit, the comparison unit is configured to receive the input voltage and the output voltage, and compare the output voltage with the input voltage to obtain a first comparison signal; and the logic unit is configured to output a first signal and a second signal according to the first comparison signal. After the pre-charging phase of the boost converter circuit ends, the comparison unit is further configured to compare the output voltage with the input voltage to obtain a second comparison signal; and the logic unit is further configured to output a third signal and a fourth signal according to the second comparison signal.

4. The precharge circuit according to claim 3, wherein The comparison unit includes a first resistor, a second resistor, a third resistor, a fourth resistor and a comparator, wherein the first end of the first resistor is used to receive the input voltage, the second end of the first resistor is respectively connected to the first end of the second resistor and the first input end of the comparator, the first end of the third resistor is used to receive the output voltage, the second end of the third resistor is respectively connected to the first end of the fourth resistor and the second input end of the comparator, the output end of the comparator is connected to the logic unit, and the second end of the second resistor and the second end of the fourth resistor are both grounded.

5. The precharge circuit according to claim 3, wherein: The logic unit includes a first inverter and a second inverter, the input end of the first inverter is connected to the comparison unit, the output end of the first inverter is connected to the input end of the second inverter and the second selection module respectively, and the output end of the second inverter is connected to the second selection module.

6. The precharge circuit according to claim 1 or 2, wherein: The second selection module includes a first switching tube and a second switching tube, the control end of the first switching tube is connected to the comparison module, the first conduction end of the first switching tube is respectively connected to the first conduction end of the second switching tube and the substrate of the freewheeling tube, the second conduction end of the first switching tube is used to receive the input voltage, the control end of the second switching tube is connected to the comparison module, and the second conduction end of the second switching tube is used to receive the output voltage.

7. The precharge circuit according to claim 1 or 2, wherein: The pre-charge current module includes a third switch tube and a current source, the first conduction end of the third switch tube receives the output voltage, the control end of the third switch tube is respectively connected to the second conduction end of the third switch tube, the first end of the current source and the first selection module, and the second end of the current source is grounded.

8. The precharge circuit according to claim 1 or 2, wherein: The first selection module includes a data selector, a first data input end of the data selector is connected to the output end of the pre-charge current module, a second data input end of the data selector is used to receive the drive signal, a control end of the data selector is used to receive the pre-charge signal, and an output end of the data selector is used to be connected to the gate of the freewheeling tube.

9. A boost converter, characterized in that: The pre-charging circuit comprises the pre-charging circuit according to any one of claims 1 to 8.

10. An electronic device, characterized in that: Including the boost converter according to claim 9.

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