Charging control circuit, buck converter, and power supply apparatus

Abstract

The invention discloses a charging control circuit, a step-down converter and power supply equipment. The charging control circuit comprises a reference voltage supply module, a comparator, a current supply module, a comparison voltage protection module and a first switching tube, the reference voltage providing module is used for providing reference voltage; the comparison voltage protection module is used for limiting the maximum value of the comparison voltage; the comparator is used for outputting 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 for providing charging current for the first switching tube when a high-level signal is accessed; and the first switching tube is used for being switched on or switched off under the control of the charging control signal, and adopts the charging current to charge a BOOT capacitor connected with the BOOT pin when the first switching tube is switched on. According to the invention, the stability of the output voltage VOUT of the buck converter can be improved.

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 upper bridge (HS) and lower bridge (LS) switching devices, considering the cost and voltage resistance characteristics. 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 (switching 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, and 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 end of the upper bridge drive buck converter floats with the SW pin.

[0003] Because the upper bridge switch needs to be charged and discharged when driving, the voltage of capacitor C3 will be reduced and must be charged. Usually when the lower bridge switch is turned on SW=GND, capacitor C3 can be charged by the low voltage power supply inside the chip. The relevant charging circuit can be referred to Figure 2 As shown, the capacitor C3 is charged by the internal low voltage VCC (such as 5V) of the chip through the charging circuit.

[0004] by Figure 1Taking the buck converter shown in FIG. 1 as an example for analysis, the inventor found that the condition for charging the BOOT capacitor with the internal low voltage VCC of the chip is SW=GND, that is, when the lower bridge switch is turned on. However, in application, sometimes when the chip is turned on, the output voltage VOUT is not zero. At this time, the action of the chip is usually to turn off the upper and lower bridge switches. It is necessary to wait until the internal soft start voltage is equal to the setting pin (such as the FB pin) voltage before the upper and lower bridge switches start to act to avoid excessive surge current. Because the upper and lower bridges are turned off, the SW pin voltage SW=VOUT is not zero, so the low voltage power supply cannot charge the BOOT capacitor. The lower bridge switch must be turned on first to charge the BOOT capacitor, and the chip can work normally. At this time, because the inductor L1 has not been replenished with energy by the upper bridge switch, turning on the lower bridge first will interfere with the output voltage VOUT. In addition, the buck converter under high voltage and high current environment is usually equipped with a power saving mode (PSM mode). In the power saving mode, the upper and lower bridge switches are closed until the voltage of the setting pin (such as FB voltage) is less than the internal reference voltage. At this time, the conditions such as SW=VOUT are not zero. If you need to jump out of the power saving mode and enter the normal operation mode, you must first open the lower bridge switch to charge the BOOT capacitor, which will also cause interference to VOUT. It can be seen that Figure 1 Buck converters of this type 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 a traditional buck converter.

[0006] The present application provides a charging control circuit, including a reference voltage providing module, a comparator, a current providing module, a comparison voltage protection module and a first switch tube; The gate of the first switch tube is used to access 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; 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 used for outputting 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 switch 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 it is turned on.

[0007] 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, and the second end serves as the output end of the current 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.

[0008] 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.

[0009] Optionally, the current providing module includes a second current source, a second switch tube and a current mirror; the gate of the second switch 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 of the first switch tube.

[0010] Optionally, the current mirror includes a first MOS tube, a second MOS tube and a third switch; the drain of the first MOS tube serves as the input end of the current mirror, and is respectively connected to the drain of the second switch tube, the gate of the first MOS tube, the gate of the second MOS tube 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 tube; the drain of the second MOS tube serves as the output end of the current mirror, and is connected to the drain of the first switch tube.

[0011] 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.

[0012] The present application also provides a buck converter, which includes any one of the above-mentioned charging control circuits.

[0013] 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.

[0014] Optionally, the buck converter further includes a control module; the control module is respectively connected to a control end of the first switch and a control end of the second switch to control the on and off of the first switch and the second switch.

[0015] The present application also provides a power supply device, which includes at least one buck converter of any one of the above types.

[0016] 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, and 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

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. 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.

[0018] Figure 1 It is a schematic diagram of the buck converter structure during the research process of this application; Figure 2 It is a partial structural schematic diagram of the buck converter in the research process of this application; Figure 3 is a schematic diagram of the charging control circuit structure of an embodiment of the present application; Figure 4 It is a schematic diagram of the charging control circuit structure of another embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0020] In a first aspect, the present application provides a charging control circuit, which is disposed inside a buck converter and can be used to control the charging of a BOOT capacitor between a BOOT pin and a SW pin of the buck converter. In some embodiments, the BOOT capacitor can also be called a bootstrap capacitor.

[0021] 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.

[0022] The gate of the first switch tube K1 is used to access the charging control signal CC, the source of the first switch tube K1 is connected to the BOOT pin of the buck converter, and the drain of the first switch tube K1 is respectively connected to the output end of the current supply module 130, the first end of the comparison voltage protection module 140 and the negative input end of the comparator 120. The positive input end of the comparator 120 is connected to the output end of the reference voltage supply module 110, and the output end of the comparator 120 is connected to the input end of the current supply module 130. The second end of the comparison voltage protection module 140 is grounded.

[0023] The reference voltage providing module 110 is used to provide a reference voltage VREF.

[0024] The comparison voltage protection module 140 is used to limit the maximum value of the comparison voltage VFB.

[0025] The comparator 120 is used for outputting 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 .

[0026] The current providing module 130 is used to provide a charging current to the first switch tube K1 when a high level signal is connected.

[0027] The first switch tube K1 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 CB connected to the BOOT pin when it is turned on.

[0028] 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 does not need to be charged, 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 needs to be charged, 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 according to factors such as the working mode of the buck converter, the control logic of the internal upper bridge switch and the lower bridge switch. For example, in some working modes, when the lower bridge switch of the buck converter is turned on, the charging control signal is a high level, and when the upper bridge switch of the buck converter is turned on, the charging control signal is a low level, so that the charging control signal is a high level when the BOOT capacitor CB needs to be charged, and is a low level when the BOOT capacitor CB does not need to be charged.

[0029] In the above charging control circuit, the current providing module 130 charges the BOOT capacitor CB through the input voltage VIN connected to the voltage input terminal VIN, and the BOOT capacitor CB can be fully charged in advance when VSW=VOUT is not zero. When the buck converter is to restore the PWM mode, the upper bridge switch can be turned on first to avoid interfering with the output voltage VOUT, and there is no need to switch back and forth between the low voltage source and the high voltage source for charging, which can improve the stability of the output voltage VOUT, thereby improving the working performance of the buck converter.

[0030] In some embodiments, the reference voltage providing module 110 includes a first current source CS1 , a voltage control resistor R1 , and a first switch S1 .

[0031] The input end of the first current source CS1 is connected to the voltage input end VIN, and the second end of the first current source CS1 is used as the output end of the reference voltage providing module 110, and is respectively connected to the positive input end of the comparator 120 and the first end of the voltage control resistor R1. The second end of the voltage control resistor R1 is grounded through the first switch S1, that is, the second end of the voltage control resistor R1 is connected to the first end of the first switch S1, and the second end of the first switch S1 is grounded.

[0032] The voltage control resistor R1 can provide a voltage signal with a preset voltage higher than the voltage at the first switch S1 after the first switch S1 is closed, and the voltage signal is the reference voltage VREF; optionally, when the first switch S1 is closed, the magnitude of the reference voltage VREF is VREF=I1*R1, where I1 is the magnitude of the output current of the first current source CS1, and R1 is the resistance value of the voltage control resistor R1. Optionally, the parameters of the first current source CS1 and the voltage control resistor R1 can be determined based on the magnitude of the reference voltage VREF required to be connected to the positive input terminal of the comparator 120, wherein the reference voltage VREF is usually a voltage value greater than the comparison voltage VFB.

[0033] 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 and avoid interference caused by the corresponding voltage jump of the SW pin, thereby improving the reliability of the corresponding charging control process.

[0034] 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 a second end of the voltage control resistor R1, and a second end of the second switch S2 is connected to a SW pin of the buck converter; the second switch S2 is used to connect the voltage control resistor R1 to the SW pin of the buck converter, so that the reference voltage VREF is VSW+ I1*R1; wherein VSW is the voltage of the SW pin.

[0035] Specifically, the first switch S1 is used for the normal operation of the buck converter, for example, it is closed when performing PWM (pulse width modulation) operation, so that the voltage control resistor R1 is connected to the ground terminal, so that the magnitude of the reference voltage VREF is I1*R1. The second switch S2 is used to be closed when the buck converter is in a specific working mode such as pre-load mode or PSM (power saving) mode, so that the voltage control resistor R1 is connected to the SW pin of the buck converter, so that the magnitude of the reference voltage VREF is VSW+ I1*R1. In this way, when the buck converter performs PWM operation and other operations, the first switch S1 is turned on, the second switch S2 is turned off, and the magnitude of the reference voltage VREF is I1*R1 (for example, 5V); when the lower bridge switch of the buck converter is turned on, the first switch tube 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 tube 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 working mode such as pre-load mode or PSM (power saving) mode, the first switch S1 is turned off, the second switch S2 is turned on, and the reference voltage VREF is VSW+ I1*R1. When the upper bridge switch and the lower bridge switch of the buck converter are both turned off, the first switch tube 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 resume the PWM mode, the first switch tube K1 is turned off to ensure that the BOOT capacitor CB does not leak to the voltage input terminal VIN.

[0036] In this embodiment, the current providing module 130 charges the BOOT capacitor CB through the input voltage VIN connected to the voltage input terminal VIN, and the BOOT capacitor CB can be fully charged in advance when VSW=VOUT is not zero. When the buck converter is to restore the PWM mode, the upper bridge switch can be turned on first to avoid interfering with the output voltage VOUT, and there is no need to switch back and forth between the low voltage source and the high voltage source for charging, which can improve the stability of the output voltage VOUT.

[0037] In some examples, both the first switch S1 and the second switch S2 may further include a control end, and the control ends of the first switch S1 and the second switch S2 may be connected to a control module inside the buck converter, respectively, 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 turned on, the other is turned off, so as to provide a suitable voltage value to the second end of the voltage control resistor R1. Optionally, the control module may input a first switch signal to the control end of the first switch S1 and a second switch signal to 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 may be turned on when the first switch signal is at a high level, and turned off when the first switch signal is at a low level; the second switch S2 may be turned on when the second switch signal is at a high level, and turned off when the second switch signal is at a low level. 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.

[0038] 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; when the buck converter is in a specific operating mode such as a pre-load mode or a PSM (power saving) mode, the control module inside the buck converter can control the first switch S1 to be turned off and the second switch S2 to be turned on.

[0039] In some embodiments, 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.

[0040] 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.

[0041] The second switch tube K2 is used to be turned on when the gate is connected to a high level, so as to connect the current provided by the second current source CS2 to the input end of the current mirror 131. The current mirror 131 is used to output the current connected to the input end to the drain of the first switch tube K1, so that the current charges the BOOT capacitor CB through the first switch tube K1.

[0042] 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; the first MOS transistor P1 and the second MOS transistor P2 are both PMOS transistors. The drain of the first MOS transistor P1 serves as the input end of the current mirror 131, and is respectively connected to the drain of the second switch tube K2, the gate of the first MOS transistor P1, the gate of the second MOS transistor P2 and the first end of the third switch S3, and the source of the first MOS transistor P1 is respectively connected to the voltage input end VIN, the second end 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 end of the current mirror 131, and is connected to the drain of the first switch tube K1.

[0043] In some embodiments, 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 end of the first diode D1 is grounded through the fourth switch S4, and the ground end can be the second end of the comparison voltage protection module 140; the output end of the first diode D1 is used as the first end of the comparison voltage protection module 140, and is connected to the drain of the first switch tube K1. The first diode D1 is a voltage stabilizing diode, so that the maximum value of the voltage difference between the output end (such as) and the input end of the first diode D1 is its breakdown voltage. At this time, the first end of the comparison voltage protection module 140 is the breakdown voltage of the first diode D1, and the maximum value of the comparison voltage VFB output to the negative input end of the comparator 120 is the breakdown voltage of the first diode D1.

[0044] 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 PWM operation and 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 tube 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 tube 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 working 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 the upper bridge switch and the lower bridge switch of the buck converter are both turned off, the first switch tube 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 resume the PWM mode, the first switch tube K1 is turned off to ensure that the BOOT capacitor CB will not leak to the voltage input terminal VIN; at this time, the first pulse used to control the upper bridge switch and the lower bridge switch is the upper bridge switch turned on, VSW=VIN, instead of the lower bridge switch turned on, VSW=GND, the output terminal current changes from extremely light load to loaded, that is, when the buck converter changes from power saving mode to PWM, the output terminal voltage VOUT can respond in real time without too much voltage drop, and the stability is improved.

[0045] 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.

[0046] In the above charging control circuit, the current providing module 130 charges the BOOT capacitor CB through the input voltage VIN connected to the voltage input terminal VIN, so that the BOOT capacitor CB can be fully charged in advance when 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, and there is no need to switch back and forth between the low voltage source and the high voltage source for charging, which can improve the stability of the output voltage VOUT. When the buck converter performs PWM operation and 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 tube 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 tube 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 working 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 the upper bridge switch and the lower bridge switch of the buck converter are both turned off, the first switch tube 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 resume the PWM mode, the first switch tube K1 is turned off to ensure that the BOOT capacitor CB does not leak to the voltage input terminal VIN; thus improving the working stability of the buck converter in each working mode and mode switching process. It can be seen that the above charging control circuit can improve its reliability in many aspects.

[0047] A second aspect of the present application provides a buck converter, wherein the buck converter includes the charging control circuit described in any one of the above embodiments.

[0048] In some embodiments, 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.

[0049] In some embodiments, the buck converter further includes a control module (not shown); the control module is respectively connected to a control end of the first switch S1 and a control end of the second switch S2 to control the on and off of the first switch S1 and the second switch S2.

[0050] Optionally, the control module can input a first switch signal to the control end of the first switch S1 and a second switch signal to 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 first switch signal is at a high level, and turned off when the first switch signal is at a low level; the second switch S2 can be turned on when the second switch signal is at a high level, and turned off when the second switch signal is at a low level. Optionally, the control module can input a third switch signal to the control end of the first switch S1 and the control end of the second switch S2 at the same time 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.

[0051] Optionally, the control module is respectively connected to a control end of the third switch S3 and / or a control end of the fourth switch S4 to respectively control the on and off of the third switch S3 and / or the fourth switch S4.

[0052] The above-mentioned buck converter includes the charging control circuit described in any of the above-mentioned embodiments, and has all the beneficial effects of the charging control circuit described in any of the above-mentioned embodiments, which will not be repeated here.

[0053] A third aspect of the present application provides a power supply device, which includes at least one buck converter as described in any of the above embodiments.

[0054] 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.

[0055] 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 based on reading and understanding this specification and the accompanying drawings. The present 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 above-mentioned components, the terms used to describe such components are intended to correspond to any component (unless otherwise indicated) that performs the specified function of the component (e.g., it is functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the function in the exemplary implementation of the present specification shown herein.

[0056] That is, the above description is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0057] 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 drawings, which are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 a limitation on 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 for identification. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of 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, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0058] In this application, the word "exemplary" is used to mean "used as an example, illustration or description". Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or more advantageous than other embodiments. In order to enable any technician in the field to implement and use the present application, the present application provides the above description. 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 unnecessary details that make the description of the present application obscure. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in the present 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 switch tube; The gate of the first switch tube is used to access 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 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 used for outputting 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 switch 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 it is turned on.

2. The charging control circuit according to claim 1, characterized in that: The reference voltage providing module includes a first current source, a voltage-controlled resistor and a first switch; The input end of the first current source is connected to the voltage input end, and the second end serves as the output end of the current 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.

3. The charging control circuit according to claim 2, characterized in that: 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.

4. The charging control circuit according to claim 1, characterized in that: The current providing module includes a second current source, a second switch tube and a current mirror; The gate of the second switch tube serves as the input end of the current providing module and is 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 and is connected to the drain of the first switch tube.

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

6. The charging control circuit according to claim 1, characterized in that: 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.

7. A buck converter, characterized in that: The buck converter comprises a charging control circuit as claimed in any one of claims 1 to 6.

8. The buck converter according to claim 7, characterized in that The buck converter also includes a BOOT capacitor and a second diode; The BOOT capacitor is connected between the BOOT pin and the SW pin; the second diode is connected in parallel at both ends of the BOOT capacitor.

9. The buck converter according to claim 7, characterized in that: The buck converter also 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.

10. A power supply device, characterized in that: The power supply device comprises at least one buck converter as claimed in any one of claims 7 to 9.

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