Charging control circuit, buck converter and power supply equipment

Abstract

The present application discloses a charging control circuit, a buck converter, and a power supply device. The charging control circuit includes a reference voltage supply module, a comparator, a current supply module, a comparison voltage protection module, and a first switching tube. The reference voltage supply module is used to provide a reference voltage; the comparison voltage protection module is used to limit the maximum value of the comparison voltage; the comparator is used to output a high-level signal to the current supply module when the reference voltage is greater than the comparison voltage; the current supply module is used to provide a charging current to the first switching tube when a high-level signal is received; the first switching tube is used to turn on or off under the control of the charging control signal, and when turned on, uses the charging current to charge the BOOT capacitor connected to the BOOT pin. This application can improve the stability of the output voltage VOUT of the buck converter.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a charging control circuit, a buck converter, and a power supply device. Background Art

[0002] In a buck converter under high voltage and high current environment, high voltage NMOSFET is usually used as the high bridge (HS) and low bridge (LS) switching devices due to cost and voltage resistance. And because the control circuit and the drive circuit are both low voltage devices, a capacitor must be added between the BOOT pin (boost pin) and the SW pin (switch pin) of the buck converter. For example, if the buck converter includes Figure 1 For the chip shown in the figure, the BOOT pin, SW pin, VIN pin, GND pin, EN pin, SS pin, RT / CLK pin and FB pin are the pins of the chip respectively. The capacitor C3 is the capacitor between the BOOT pin and the SW pin (it can be called the BOOT capacitor). The capacitor C3 can power the upper bridge drive circuit when the negative terminal of the upper bridge drive buck converter floats with the SW pin.

[0003] Because the high-side switch requires charging and discharging current, the voltage of capacitor C3 will be reduced and must be charged. Usually, when the low-side switch is turned on, SW=GND, capacitor C3 can be charged by the chip's internal low-voltage power supply. The relevant charging circuit can be referred to Figure 2 As shown, the capacitor C3 is charged by the low voltage VCC (such as 5V) inside the chip through the charging circuit.

[0004] by Figure 1Taking the buck converter shown in Figure 1 as an example, the inventors discovered that the chip's internal low-voltage VCC must be set to GND, meaning that the low-side switch is on. However, in practice, the output voltage VOUT is sometimes non-zero when the chip is turned on. In these cases, the chip typically turns off the high- and low-side switches. The high- and low-side switches must not be activated until the internal soft-start voltage reaches the voltage on the set pin (e.g., the FB pin) to prevent excessive inrush current. Because the high- and low-side switches are off, the SW pin voltage (SW=VOUT) is non-zero, preventing the low-voltage power supply from charging the boot capacitor. The low-side switch must be turned on first to fully charge the boot capacitor for the chip to function properly. However, because inductor L1 has not yet been energized by the high-side switch, turning on the low-side switch first can interfere with the output voltage VOUT. Furthermore, buck converters operating in high-voltage and high-current environments typically feature a power-saving mode (PSM). In PSM, the upper and lower switches remain closed until the voltage on the set pin (e.g., FB) falls below an internal reference voltage. If SW = VOUT and VOUT is non-zero, exiting PSM and entering normal operation requires first opening the lower switch to charge the BOOT capacitor, which can interfere with VOUT. This is evident. Figure 1 Buck converters such as the one shown have the problem of unstable output voltage. Summary of the Invention

[0005] In view of this, the present application provides a charging control circuit, a buck converter and a power supply device to solve the problem of unstable output voltage of traditional buck converters.

[0006] The present application provides a charging control circuit, comprising a reference voltage providing module, a comparator, a current providing module, a comparison voltage protection module and a first switching tube;

[0007] The gate of the first switching tube is used to receive the charging control signal, the source is connected to the BOOT pin of the buck converter, and the drain is respectively connected to the output end of the current supply module, the first end of the comparison voltage protection module, and the negative input end of the comparator; the positive input end of the comparator is connected to the output end of the reference voltage supply module, and the output end is connected to the input end of the current supply module; the second end of the comparison voltage protection module is grounded;

[0008] The reference voltage providing module is used to provide a reference voltage;

[0009] The comparison voltage protection module is used to limit the maximum value of the comparison voltage;

[0010] The comparator is configured to output a high level signal to the current providing module when the reference voltage is greater than the comparison voltage;

[0011] The current providing module is used to provide a charging current to the first switching tube when a high level signal is connected;

[0012] The first switch tube is used to be turned on or off under the control of the charging control signal, and to use the charging current to charge the BOOT capacitor connected to the BOOT pin when it is turned on.

[0013] Optionally, the reference voltage providing module includes a first current source, a voltage-controlling resistor and a first switch; the input end of the first current source is connected to the voltage input end, the output end of the first current source serves as the output end of the reference voltage providing module, and is respectively connected to the positive input end of the comparator and the first end of the voltage-controlling resistor; the second end of the voltage-controlling resistor is connected to the first end of the first switch, and the second end of the first switch is grounded.

[0014] Optionally, the reference voltage providing module further includes a second switch; a first end of the second switch is connected to the second end of the voltage-controlling resistor, and a second end of the second switch is connected to the SW pin of the buck converter.

[0015] Optionally, the current providing module includes a second current source, a second switching tube and a current mirror; the gate of the second switching tube serves as the input end of the current providing module, connected to the output end of the comparator, the source is connected to the input end of the second current source, and the drain is connected to the input end of the current mirror; the output end of the second current source is grounded; the output end of the current mirror serves as the output end of the current providing module, connected to the drain end of the first switching tube.

[0016] Optionally, the current mirror includes a first MOS transistor, a second MOS transistor and a third switch; the drain of the first MOS transistor serves as the input end of the current mirror and is respectively connected to the drain of the second switch transistor, the gate of the first MOS transistor, the gate of the second MOS transistor and the first end of the third switch, and the source is respectively connected to the voltage input end, the second end of the third switch and the source of the second MOS transistor; the drain of the second MOS transistor serves as the output end of the current mirror and is connected to the drain of the first switch transistor.

[0017] Optionally, the comparison voltage protection module includes a first diode and a fourth switch; the input end of the first diode is grounded through the fourth switch, and the output end serves as the first end of the comparison voltage protection module and is connected to the drain of the first switch tube.

[0018] The present application also provides a buck converter, which includes any of the above-mentioned charging control circuits.

[0019] Optionally, the buck converter further includes a BOOT capacitor and a second diode; the BOOT capacitor is connected between the BOOT pin and the SW pin; and the second diode is connected in parallel across the BOOT capacitor.

[0020] Optionally, the buck converter further includes a control module; the control module is connected to the control end of the first switch and the control end of the second switch respectively to control the on and off of the first switch and the second switch.

[0021] The present application also provides a power supply device, which includes at least one buck converter of any one of the above types.

[0022] In the above-mentioned charging control circuit, buck converter and power supply device of the present application, the current providing module charges the BOOT capacitor through the input voltage connected to the voltage input terminal, so that the BOOT capacitor can be fully charged in advance when the SW pin voltage VSW=VOUT is not zero. When the buck converter wants to restore the PWM mode, the upper bridge switch can be turned on first to avoid interfering with the output voltage VOUT. There is no need to switch back and forth between the low-voltage voltage source and the high-voltage voltage source for charging, which can improve the stability of the output voltage VOUT. 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 description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic diagram of the buck converter structure used in the research process of this application;

[0025] Figure 2 This is a partial structural diagram of the buck converter used in the research process of this application;

[0026] Figure 3 This is a schematic diagram of the charging control circuit structure of an embodiment of the present application;

[0027] Figure 4 This is a schematic diagram of the charging control circuit structure of another embodiment of the present application. DETAILED DESCRIPTION

[0028] The following, in conjunction with the accompanying drawings, clearly and completely describes the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0029] In a first aspect, the present application provides a charging control circuit, which is provided within a buck converter and can be used to control the charging of a BOOT capacitor between the BOOT pin and the SW pin of the buck converter. In some embodiments, the BOOT capacitor may also be referred to as a bootstrap capacitor.

[0030] refer to Figure 3 As shown, the charging control circuit includes a reference voltage providing module 110 , a comparator 120 , a current providing module 130 , a comparison voltage protection module 140 and a first switch tube K1 .

[0031] The gate of the first switch K1 is connected to the charging control signal CC. The source of the first switch K1 is connected to the BOOT pin of the buck converter. The drain of the first switch K1 is connected to the output of the current supply module 130, the first terminal of the comparison voltage protection module 140, and the negative input of the comparator 120. The positive input of the comparator 120 is connected to the output of the reference voltage supply module 110, and the output of the comparator 120 is connected to the input of the current supply module 130. The second terminal of the comparison voltage protection module 140 is grounded.

[0032] The reference voltage providing module 110 is configured to provide a reference voltage VREF.

[0033] The comparison voltage protection module 140 is configured to limit a maximum value of the comparison voltage VFB.

[0034] The comparator 120 is configured to output a high-level signal to the current providing module 130 when the reference voltage VREF is greater than the comparison voltage VFB, so as to turn on the current providing module 130 .

[0035] The current providing module 130 is configured to provide a charging current to the first switch tube K1 when a high level signal is input.

[0036] The first switch tube K1 is used to be turned on or off under the control of the charging control signal, and uses the charging current to charge the BOOT capacitor CB connected to the BOOT pin when it is turned on.

[0037] Specifically, the charging control signal may include a level signal. When the charging control signal is at a high level, the first switch tube K1 is turned on. When the charging control signal is at a low level, the first switch tube K1 is turned off. The charging control signal can be preset according to the charging requirement of the BOOT capacitor CB. When the BOOT capacitor CB needs to be charged, the charging control signal is at a high level. When the BOOT capacitor CB does not need to be charged, the charging control signal is at a low level. Optionally, the charging control signal can come from a control module inside the buck converter. The control module can detect the BOOT capacitor CB. When the voltage of the BOOT capacitor CB reaches the working requirements of the BOOT pin and the SW pin in the buck converter and no charging is required, the charging control signal is set to a low level. When the voltage of the BOOT capacitor CB does not reach the working requirements of the BOOT pin and the SW pin in the buck converter and charging is required, the charging control signal is set to a high level. Optionally, the control module inside the buck converter can also preset the charging control signal based on factors such as the buck converter operating mode, the control logic of the internal upper bridge switch and the lower bridge switch. For example, in some operating modes, when the lower bridge switch of the buck converter is turned on, the charging control signal is high, and when the upper bridge switch of the buck converter is turned on, the charging control signal is low, so that the charging control signal is high when the BOOT capacitor CB needs to be charged, and is low when the BOOT capacitor CB does not need to be charged.

[0038] In the charging control circuit described above, the current providing module 130 charges the BOOT capacitor CB via the input voltage VIN connected to the voltage input terminal VIN. This allows the BOOT capacitor CB to be fully charged in advance when VSW = VOUT is non-zero. When the buck converter resumes PWM mode, the high-side switch can be turned on first, avoiding interference with the output voltage VOUT and eliminating the need to switch back and forth between the low-voltage and high-voltage voltage sources. This improves the stability of the output voltage VOUT, thereby enhancing the performance of the buck converter.

[0039] In some embodiments, the reference voltage providing module 110 includes a first current source CS1 , a voltage-controlling resistor R1 , and a first switch S1 .

[0040] An input terminal of the first current source CS1 is connected to the voltage input terminal VIN. A second terminal of the first current source CS1 serves as an output terminal of the reference voltage providing module 110 and is connected to the positive input terminal of the comparator 120 and the first terminal of the voltage-controlling resistor R1, respectively. The second terminal of the voltage-controlling resistor R1 is grounded via a first switch S1. That is, the second terminal of the voltage-controlling resistor R1 is connected to the first terminal of the first switch S1, and the second terminal of the first switch S1 is grounded.

[0041] The voltage-controlling resistor R1 can provide a voltage signal that is a predetermined voltage higher than the voltage at the first switch S1 after the first switch S1 is closed. This voltage signal is the reference voltage VREF. Optionally, when the first switch S1 is closed, the reference voltage VREF is VREF=I1*R1, where I1 is the output current of the first current source CS1 and R1 is the resistance of the voltage-controlling resistor R1. Optionally, the parameters of the first current source CS1 and the voltage-controlling resistor R1 can be determined based on the reference voltage VREF required to be connected to the positive input of the comparator 120. The reference voltage VREF is typically a voltage greater than the comparison voltage VFB.

[0042] In this embodiment, the second end of the voltage-controlling resistor R1 is grounded through the first switch S1, which can make the reference voltage VREF provided by the first end of the voltage-controlling resistor R1 more stable, avoid interference caused by the corresponding voltage jump of the SW pin, and thus improve the reliability of the corresponding charging control process.

[0043] In some examples, the reference voltage providing module 110 further includes a second switch S2. A first end of the second switch S2 is connected to the second end of the voltage-controlling resistor R1, and a second end of the second switch S2 is connected to the SW pin of the buck converter. The second switch S2 is configured to connect the voltage-controlling resistor R1 to the SW pin of the buck converter, so that the reference voltage VREF is VSW + I1*R1, where VSW is the voltage at the SW pin.

[0044] Specifically, the first switch S1 is used for normal buck converter operation, such as when performing PWM (pulse width modulation) operation. It closes, connecting the voltage-controlling resistor R1 to ground, ensuring that the reference voltage VREF is equal to I1*R1. The second switch S2 is used to close when the buck converter is in a specific operating mode, such as pre-load mode or PSM (power saving mode), connecting the voltage-controlling resistor R1 to the buck converter's SW pin, ensuring that the reference voltage VREF is equal to VSW + I1*R1. Thus, when the buck converter is performing PWM operation, the first switch S1 is on and the second switch S2 is off, resulting in a reference voltage VREF of I1*R1 (e.g., 5V). When the buck converter's lower-bridge switch is on, the first switch K1 is on, and the current supply module 130 charges the boot capacitor CB to VBOOT = VREF = I1*R1. When the buck converter's upper-bridge switch is on, the first switch K1 is off, ensuring that the boot capacitor CB does not leak current to the voltage input terminal VIN. When the buck converter is in a specific operating mode, such as pre-load mode or PSM (power saving mode), the first switch S1 is off and the second switch S2 is on. The reference voltage VREF is VSW + I1*R1. When both the high-bridge and low-bridge switches of the buck converter are off, the first switch K1 is on, and the current supply module 130 charges the boot capacitor CB to VBOOT = VREF = VSW + I1*R1. When the buck converter is about to return to PWM mode, the first switch K1 is turned off to prevent the boot capacitor CB from leaking to the voltage input terminal VIN.

[0045] In this embodiment, the current providing module 130 charges the BOOT capacitor CB via the input voltage VIN connected to the voltage input terminal VIN. This allows the BOOT capacitor CB to be fully charged in advance when VSW = VOUT is non-zero. When the buck converter resumes PWM mode, the high-side switch can be turned on first to avoid interference with the output voltage VOUT. This eliminates the need to switch back and forth between the low-voltage and high-voltage voltage sources for charging, thereby improving the stability of the output voltage VOUT.

[0046] In some examples, both the first switch S1 and the second switch S2 may further include control terminals, and the control terminals of the first switch S1 and the second switch S2 may be connected to a control module within the buck converter, so that the control module controls the on and off of the first switch S1 and the second switch S2; wherein when one of the first switch S1 and the second switch S2 is on, the other is off, thereby providing a suitable voltage value to the second end of the voltage-control resistor R1. Optionally, the control module may input a first switching signal to the control terminal of the first switch S1 and a second switching signal to the control terminal of the second switch S2, respectively, based on the operating state and / or operating modulus of the buck converter; the first switch S1 may be turned on when the first switching signal is high and turned off when the first switching signal is low; the second switch S2 may be turned on when the second switching signal is high and turned off when the second switching signal is low. Optionally, the control module can simultaneously input a third switch signal to the control end of the first switch S1 and the control end of the second switch S2 according to the working state and / or working modulus of the buck converter; the first switch S1 can be turned on when the third switch signal is at a high level and turned off when the third switch signal is at a low level; the second switch S2 can be turned off when the third switch signal is at a high level and turned on when the third switch signal is at a low level.

[0047] In some examples, the control module inside the buck converter can control the first switch S1 to be turned on and the second switch S2 to be turned off when the buck converter is operating normally, such as performing a PWM (pulse width modulation) operation; and control the first switch S1 to be turned off and the second switch S2 to be turned on when the buck converter is in a specific operating mode such as a pre-load mode or a PSM (power saving mode).

[0048] In some embodiments, as Figure 3 and Figure 4 As shown, the current providing module 130 includes a second current source CS2, a second switch tube K2 and a current mirror 131. The second switch tube K2 may be an NMOS tube.

[0049] The gate of the second switch tube K2 serves as the input end of the current providing module 130 and is connected to the output end of the comparator 120. The source of the second switch tube K2 is connected to the input end of the second current source CS2. The drain of the second switch tube K2 is connected to the input end of the current mirror 131. The output end of the second current source CS2 is grounded. The output end of the current mirror 131 serves as the output end of the current providing module 130 and is connected to the drain of the first switch tube K1.

[0050] The second switch tube K2 is configured to conduct when the gate is connected to a high level, thereby connecting the current provided by the second current source CS2 to the input terminal of the current mirror 131. The current mirror 131 is configured to output the current connected to the input terminal to the drain of the first switch tube K1, so that the current charges the BOOT capacitor CB through the first switch tube K1.

[0051] In some examples, such as Figure 3 and Figure 4 As shown, the current mirror 131 includes a first MOS transistor P1, a second MOS transistor P2, and a third switch S3; both the first MOS transistor P1 and the second MOS transistor P2 are PMOS transistors. The drain of the first MOS transistor P1 serves as the input terminal of the current mirror 131 and is respectively connected to the drain of the second switch transistor K2, the gate of the first MOS transistor P1, the gate of the second MOS transistor P2, and the first terminal of the third switch S3. The source of the first MOS transistor P1 is respectively connected to the voltage input terminal VIN, the second terminal of the third switch S3, and the source of the second MOS transistor P2. The drain of the second MOS transistor P2 serves as the output terminal of the current mirror 131 and is connected to the drain of the first switch transistor K1.

[0052] In some embodiments, as Figure 3 and Figure 4 As shown, the comparison voltage protection module 140 includes a first diode D1 and a fourth switch S4. The input terminal of the first diode D1 is grounded via the fourth switch S4. In this case, the ground terminal can be the second terminal of the comparison voltage protection module 140. The output terminal of the first diode D1 serves as the first terminal of the comparison voltage protection module 140 and is connected to the drain of the first switch K1. The first diode D1 is a voltage-stabilizing diode. The maximum voltage difference between the output terminal (e.g., ) and the input terminal of the first diode D1 is its breakdown voltage. In this case, the first terminal of the comparison voltage protection module 140 is the breakdown voltage of the first diode D1. The maximum value of the comparison voltage VFB output to the negative input terminal of the comparator 120 is the breakdown voltage of the first diode D1.

[0053] The on / off control logic of the fourth switch S4 can be consistent with the on / off control logic of the first switch S1. For example, the fourth switch S4 can be turned on when the first switch S1 is turned on, and turned off when the first switch S1 is turned off. Specifically, when the buck converter performs a PWM operation, the first switch S1 and the fourth switch S4 are turned on, the second switch S2 is turned off, and the reference voltage VREF is equal to I1*R1. When the lower bridge switch of the buck converter is turned on, the first switch K1 is turned on, and the current supply module 130 charges the BOOT capacitor CB to VBOOT = VREF = I1*R1. When the upper bridge switch of the buck converter is turned on, the first switch K1 is turned off, ensuring that the BOOT capacitor CB does not leak current to the voltage input terminal VIN. When the buck converter is in a specific operating mode, such as pre-load mode or PSM (power saving mode), the first switch S1 and the fourth switch S4 are off, the second switch S2 is on, and the reference voltage VREF is VSW + I1*R1. When both the high-bridge and low-bridge switches of the buck converter are off, the first switch K1 is on, and the current supply module 130 charges the boot capacitor CB to VBOOT = VREF = VSW + I1*R1. When the buck converter is about to resume PWM mode, the first switch K1 is turned off to prevent the boot capacitor CB from leaking to the voltage input terminal VIN. In this case, the first pulse used to control the high-bridge and low-bridge switches is when the high-bridge switch is on, VSW = VIN, rather than when the low-bridge switch is on, VSW = GND. When the output current changes from extremely light load to full load, that is, when the buck converter switches from power saving mode to PWM, the output voltage VOUT can react immediately without a significant voltage drop, thus improving stability.

[0054] Optionally, the fourth switch S4 may further include a control end, and the control end of the fourth switch S4 may be connected to a control module inside the buck converter, so that the control module controls the on and off of the fourth switch S4.

[0055] In the above charging control circuit, the current providing module 130 charges the BOOT capacitor CB via the input voltage VIN connected to the voltage input terminal VIN. This allows the BOOT capacitor CB to be fully charged in advance when VSW = VOUT is not zero. When the buck converter resumes PWM mode, it can first turn on the high-side switch, avoiding interference with the output voltage VOUT and eliminating the need to switch back and forth between the low-voltage and high-voltage voltage sources for charging. This improves the stability of the output voltage VOUT. When the buck converter performs PWM operation or other operations, the first switch S1 and the fourth switch S4 are turned on, the second switch S2 is turned off, and the reference voltage VREF is I1*R1. When the lower bridge switch of the buck converter is turned on, the first switch K1 is turned on, and the current providing module 130 charges the BOOT capacitor CB to VBOOT = VREF = I1*R1. When the upper bridge switch of the buck converter is turned on, the first switch K1 is turned off to ensure that the BOOT capacitor CB does not leak to the voltage input terminal VIN. When the buck converter is in a specific operating mode such as pre-load mode or PSM (power saving mode), the first switch S1 and the fourth switch S4 are turned off, the second switch S2 is turned on, and the reference voltage VREF is VSW + I1*R1. When both the upper bridge switch and the lower bridge switch of the buck converter are turned off, the first switch K1 is turned on, and the current providing module 130 charges the BOOT capacitor CB to VBOOT = VREF = VSW + I1*R1; when the buck converter is about to return to PWM mode, the first switch K1 is turned off, ensuring that the boot capacitor CB does not leak to the voltage input terminal VIN. This improves the buck converter's operating stability in various operating modes and during mode switching. This charging control circuit can improve its reliability in many ways.

[0056] A second aspect of the present application provides a buck converter, which includes the charging control circuit described in any one of the above embodiments.

[0057] In some embodiments, as Figure 3 and Figure 4 As shown, the buck converter further includes a BOOT capacitor CB and a second diode D2; the BOOT capacitor CB is connected between the BOOT pin and the SW pin; the second diode D2 is connected in parallel at both ends of the BOOT capacitor to prevent current or related electrical signals from flowing from the BOOT pin to the SW pin.

[0058] In some embodiments, the buck converter further includes a control module (not shown); the control module is connected to the control end of the first switch S1 and the control end of the second switch S2 to control the on and off of the first switch S1 and the second switch S2.

[0059] Optionally, the control module may input a first switching signal to the control end of the first switch S1 and a second switching signal to the control end of the second switch S2, respectively, based on the operating state and / or operating modulus of the buck converter; the first switch S1 may be turned on when the first switching signal is at a high level and turned off when the first switching signal is at a low level; the second switch S2 may be turned on when the second switching signal is at a high level and turned off when the second switching signal is at a low level. Optionally, the control module may input a third switching signal to the control end of the first switch S1 and the control end of the second switch S2 simultaneously, based on the operating state and / or operating modulus of the buck converter; the first switch S1 may be turned on when the third switching signal is at a high level and turned off when the third switching signal is at a low level; the second switch S2 may be turned off when the third switching signal is at a high level and turned on when the third switching signal is at a low level.

[0060] Optionally, the control module is connected to the control end of the third switch S3 and / or the control end of the fourth switch S4 to control the on and off of the third switch S3 and / or the fourth switch S4 respectively.

[0061] The buck converter includes the charging control circuit described in any of the above embodiments, and has all the beneficial effects of the charging control circuit described in any of the above embodiments, which will not be described in detail here.

[0062] A third aspect of the present application provides a power supply device, which includes at least one buck converter described in any of the above embodiments.

[0063] The above-mentioned power supply device includes the buck converter described in any of the above-mentioned embodiments, and has all the beneficial effects of the buck converter described in any of the above-mentioned embodiments, which will not be repeated here.

[0064] Although the present application has been shown and described with respect to one or more implementations, equivalent variations and modifications will occur to those skilled in the art upon reading and understanding this specification and the accompanying drawings. This application includes all such modifications and variations and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the components described above, the terms used to describe such components are intended to correspond to any component (unless otherwise indicated) that performs the designated function of the component (e.g., which is functionally equivalent), even if the structure is not identical to the disclosed structure that performs the function in the exemplary implementation of this specification shown herein.

[0065] That is, the above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the description and drawings of this application, such as the mutual combination of technical features between the various embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0066] In addition, in the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, for structural elements with the same or similar characteristics, the present application may use the same or different reference numerals to identify them. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0067] In this application, the word "exemplary" is used to mean "serving as an example, illustration or description". Any embodiment described in this application as "exemplary" is not necessarily to be construed as being more preferred or more advantageous than other embodiments. The above description is provided to enable any person skilled in the art to implement and use the present application. In the above description, various details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other embodiments, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

Claims

1. A charging control circuit, characterized in that: The charging control circuit includes a reference voltage providing module, a comparator, a current providing module, a comparison voltage protection module and a first switching tube; The gate of the first switching tube is used to receive a charging control signal, the source of the first switching tube is connected to the BOOT pin of the buck converter, and the drain of the first switching tube is respectively connected to the output end of the current supply module, the first end of the comparison voltage protection module, and the negative input end of the comparator; the positive input end of the comparator is connected to the output end of the reference voltage supply module, and the output end of the comparator is connected to the input end of the current supply module; The second terminal of the comparison voltage protection module is grounded; The reference voltage providing module is used to provide a reference voltage; The comparison voltage protection module is used to limit the maximum value of the comparison voltage; The comparator is configured to output a high level signal to the current providing module when the reference voltage is greater than the comparison voltage; The current providing module is used to provide a charging current to the first switching tube when a high level signal is connected; The first switch tube is used to be turned on or off under the control of the charging control signal, and to use the charging current to charge the BOOT capacitor connected to the BOOT pin when turned on; The reference voltage providing module includes a first current source, a voltage-controlling resistor and a first switch; the input end of the first current source is connected to the voltage input end, and the output end of the first current source serves as the output end of the reference voltage providing module, which is respectively connected to the positive input end of the comparator and the first end of the voltage-controlling resistor; the second end of the voltage-controlling resistor is connected to the first end of the first switch, and the second end of the first switch is grounded.

2. The charging control circuit according to claim 1, wherein: The reference voltage providing module further includes a second switch; A first end of the second switch is connected to the second end of the voltage-controlling resistor, and a second end of the second switch is connected to the SW pin of the buck converter.

3. The charging control circuit according to claim 1, wherein: The current providing module includes a second current source, a second switch tube and a current mirror; The gate of the second switching tube serves as the input end of the current providing module and is connected to the output end of the comparator. The source of the second switching tube is connected to the input end of the second current source. The drain of the second switching tube is connected to the input end of the current mirror. The output end of the second current source is grounded. The output end of the current mirror serves as the output end of the current providing module and is connected to the drain end of the first switching tube.

4. The charging control circuit according to claim 3, characterized in that: The current mirror includes a first MOS transistor, a second MOS transistor and a third switch; The drain of the first MOS transistor serves as the input end of the current mirror and is respectively connected to the drain of the second switch transistor, the gate of the first MOS transistor, the gate of the second MOS transistor, and the first end of the third switch; the source of the first MOS transistor is respectively connected to the voltage input end, the second end of the third switch, and the source of the second MOS transistor; the drain of the second MOS transistor serves as the output end of the current mirror and is connected to the drain of the first switch transistor.

5. The charging control circuit according to claim 1, wherein: The comparison voltage protection module includes a first diode and a fourth switch; The input end of the first diode is grounded through the fourth switch, and the output end of the first diode serves as the first end of the comparison voltage protection module and is connected to the drain of the first switch tube.

6. A buck converter, characterized in that: The buck converter comprises the charging control circuit according to any one of claims 1 to 5.

7. The buck converter according to claim 6, wherein: The buck converter further includes a BOOT capacitor and a second diode; The BOOT capacitor is connected between the BOOT pin and the SW pin of the buck converter; the second diode is connected in parallel across the two ends of the BOOT capacitor.

8. The buck converter according to claim 6, wherein: The buck converter further includes a control module; the reference voltage providing module of the charging control circuit further includes a second switch; a first end of the second switch is connected to the second end of the voltage control resistor, and a second end is connected to the SW pin of the buck converter; The control module is connected to the control end of the first switch and the control end of the second switch respectively to control the on and off of the first switch and the second switch.

9. A power supply device, characterized in that: The power supply device comprises at least one buck converter according to any one of claims 6 to 8.

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