Bootstrap capacitor charging circuit of multi-phase voltage converter and multi-phase voltage converter

Abstract

The embodiment of the invention provides a bootstrap capacitor charging circuit of a multi-phase voltage converter and the multi-phase voltage converter, the bootstrap capacitor charging circuit comprises a judgment circuit, a latch circuit and a standby charging circuit, the judgment circuit is coupled with the two ends of a bootstrap capacitor, and the latch circuit is coupled with the two ends of the bootstrap capacitor. The judgment unit is configured to judge whether the voltage difference between the two ends of a bootstrap capacitor is larger than or equal to a preset voltage value or not and output a judgment result signal, and the bootstrap capacitor is a bootstrap capacitor of a standby phase; the latch circuit is configured to latch the judgment result signal when an upper power tube of a working phase in the multi-phase voltage converter is switched off, and an output signal of the latch circuit is a charging indication signal; and the standby charging circuit is configured to form a charging path between the working phase and the bootstrap capacitor, and control whether to charge the bootstrap capacitor of the standby phase through the working phase or not according to the charging indication signal. The problem that the transient response performance is affected due to the fact that the bootstrap capacitor of the standby phase in the multi-phase voltage converter cannot be charged is solved.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the technical field of integrated circuits, and in particular, to a bootstrap capacitor charging circuit of a multi-phase voltage converter and a multi-phase voltage converter. Background Art

[0002] Multiphase voltage converters (MPRCs) are becoming increasingly common in today's computing landscape. They connect multiple power-stage components (such as power MOSFETs and inductors) in parallel, sharing common outputs and output capacitors. Compared to traditional single-phase voltage converters, MRCs can effectively reduce RMS current consumption and the need for components like input and output capacitors. They significantly improve thermal performance under high load current conditions, optimizing output efficiency and delivering superior performance in response to load-triggered transients.

[0003] While multiphase voltage converters offer numerous advantages over single-phase converters, their implementation is also more complex. Multiphase control circuits typically add or remove phases based on load current to achieve the optimal efficiency configuration for various application conditions. Under light load current conditions, switching losses dominate. In these cases, fewer phases are used to minimize switching losses. Under heavy load current conditions, conduction losses dominate. In these cases, more phases are used to minimize conduction losses.

[0004] like Figure 1 The figure shows a schematic diagram of the structure of a multi-phase voltage converter, including two phases, Phase 1 and Phase 2. The multi-phase control circuit Multi-phase Controller generates control signals (HSON, LSON) for each phase. The high-side driver circuit (High-Side Driver) and low-side driver circuit (Low-Side Driver) of each phase then obtain drive signals for the upper power tube (HS) and lower power tube (LS) to drive HS and LS. The bootstrap capacitor CBST is coupled to the switch node SW between HS and LS to power the upper power tube driver circuit. The bootstrap capacitor CBST is typically charged when the SW potential is low (e.g., when LS is on). When the multi-phase voltage converter operates under light load conditions, some phases are in standby mode. At this time, the HS and LS of these phases are both off, and the corresponding switch node SW is equal to the output voltage VOUT. If the VOUT potential is high, the bootstrap capacitors CBST of these phases will not be charged by VIN or other internal power supplies. As the standby mode is maintained, the charge on the bootstrap capacitors CBST of these phases will continue to leak. As a result, when the multi-phase control circuit determines that the load has increased and that additional phases need to be added to the working state, the HSs of these phases cannot be turned on immediately, which affects the transient response performance of the multi-phase voltage converter. Summary of the Invention

[0005] The embodiments described herein provide a bootstrap capacitor charging circuit for a multi-phase voltage converter and a multi-phase voltage converter. These circuits are designed to address the problem of a multi-phase voltage converter in which the bootstrap capacitor in the standby phase cannot be charged, resulting in the upper power transistor being unable to be immediately turned on when the converter enters the working state from the standby state, thereby affecting transient response performance.

[0006] According to a first aspect of the present disclosure, a bootstrap capacitor charging circuit for a multi-phase voltage converter is provided. The bootstrap capacitor charging circuit includes: a judgment circuit, a latch circuit, and a standby charging circuit. The judgment circuit is coupled to both ends of a bootstrap capacitor and is configured to determine whether a voltage difference across the bootstrap capacitor is greater than or equal to a preset voltage value and output a judgment result signal. The bootstrap capacitor is a bootstrap capacitor in a standby phase of the multi-phase voltage converter. The latch circuit is coupled to the judgment circuit and is configured to latch the judgment result signal when an upper power transistor in an operating phase of the multi-phase voltage converter is turned off. The output signal of the latch circuit is a charging indication signal. The operating phase is a phase that always remains in an operating state during operation of the multi-phase voltage converter. The standby charging circuit is coupled to the latch circuit, the operating phase, and one end of the bootstrap capacitor. The standby charging circuit is configured to form a charging path between the operating phase and the bootstrap capacitor and, based on the charging indication signal, control whether the bootstrap capacitor in the standby phase is charged through the operating phase.

[0007] Optionally, the standby charging circuit includes: a capacitor voltage control module, a charging capacitor, and a charging module, wherein the capacitor voltage control module is configured to provide a power supply voltage to one end of the charging capacitor when the charging indication signal indicates that the bootstrap capacitor needs to be charged, and to provide a zero voltage to one end of the charging capacitor when the charging indication signal indicates that the bootstrap capacitor does not need to be charged; the on-off of the capacitor voltage control module and the charging capacitor is controlled by a first control signal, and the first control signal is a lower power tube conduction control signal of the working phase in the low-voltage domain, and the low-voltage domain is a voltage region greater than or equal to zero voltage and less than or equal to the power supply voltage. domain; the other end of the charging capacitor is coupled to the switching node of the working phase, the switching node is a node between the upper power tube and the lower power tube, and the voltage at one end of the charging capacitor changes with the change of the voltage of the switching node of the working phase; the charging module is configured to charge the bootstrap capacitor of the standby phase through the voltage at one end of the charging capacitor, and the on and off of the charging module and the charging capacitor are controlled by a second control signal, which is an inverted signal of the upper power tube conduction control signal of the working phase in the high voltage domain, and the high voltage domain is the voltage domain where the upper power tube drive circuit of the working phase is located.

[0008] Optionally, the judgment circuit includes: a first resistor, a second resistor, a first transistor, a comparator, and an inverter, wherein one end of the first resistor is coupled to one end of the bootstrap capacitor, and the other end of the first resistor is coupled to the first electrode of the first transistor; the control electrode of the first transistor is coupled to the other end of the bootstrap capacitor, and the other end of the bootstrap capacitor is coupled to the switching node of the standby phase corresponding to the bootstrap capacitor, and the second electrode of the first transistor is respectively coupled to one end of the second resistor and the negative input end of the comparator; the other end of the second resistor is coupled to the ground end; the positive input end of the comparator is coupled to a preset reference voltage, and the output end of the comparator is coupled to the input end of the inverter; the output end of the inverter serves as the output end of the judgment circuit to output the judgment result signal.

[0009] Optionally, the latch circuit includes a latch, wherein the data input end of the latch is coupled to the judgment result signal, the clock pulse input end of the latch is coupled to the latch trigger signal, the latch trigger signal is the inverted signal of the upper power tube conduction control signal of the working phase in the low voltage domain, and the output end of the latch serves as the output end of the latch circuit to output the charging indication signal.

[0010] Optionally, the capacitor voltage control module includes: a second transistor, a third transistor, and a first switch, wherein the control electrode of the second transistor and the control electrode of the third transistor are both coupled to the charging indication signal, the first electrode of the second transistor is coupled to the power supply voltage, the first electrode of the third transistor is coupled to the ground end, the second electrode of the second transistor and the second electrode of the third transistor are both coupled to one end of the first switch; and the other end of the first switch is coupled to one end of the charging capacitor.

[0011] Optionally, the charging module includes: a fourth transistor and a fifth transistor, wherein the control electrode of the fourth transistor is coupled to the second control signal, the first electrode of the fourth transistor is coupled to one end of the charging capacitor, the control electrode of the fifth transistor and the first electrode of the fifth transistor are both coupled to one end of the bootstrap capacitor of the standby phase, and the second electrode of the fourth transistor is coupled to the second electrode of the fifth transistor.

[0012] Optionally, the second transistor is a P-type transistor, and the third transistor is an N-type transistor.

[0013] Optionally, the comparator performs comparison when the upper power tube is turned on in the working phase.

[0014] Optionally, the bootstrap capacitor charging circuit further includes: a non-standby charging circuit configured to charge the bootstrap capacitor through the power supply voltage when the lower power tube of the standby phase is turned on after the standby phase is converted from the standby state to the working state.

[0015] According to a second aspect of the present disclosure, a multi-phase voltage converter is provided, which includes n phases, where n is a positive integer greater than or equal to 2, wherein one of the n phases always remains in an operating state when the multi-phase voltage converter is operating, and the other n-1 phases switch between a standby state and an operating state according to the load of the multi-phase voltage converter, and for each of the other n-1 phases, a bootstrap capacitor charging circuit of the multi-phase voltage converter according to any one of the above-mentioned first aspects is included.

[0016] In the bootstrap capacitor charging circuit of a multi-phase voltage converter according to an embodiment of the present disclosure, if the bootstrap capacitor in the standby phase cannot be charged, the voltage difference across the bootstrap capacitor is detected to determine whether charging is required. If charging is required, the bootstrap capacitor in the standby phase is charged from the working phase by establishing a connection with the working phase. This ensures that when the standby phase transitions from standby to working mode, the bootstrap capacitor has sufficient voltage to promptly drive the upper power transistor into conduction, thereby improving the transient response performance of the multi-phase voltage converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure and are not intended to limit the present disclosure.

[0018] Figure 1 A schematic diagram of an existing multi-phase voltage converter is shown;

[0019] Figure 2 An exemplary circuit diagram of a conventional bootstrap capacitor charging is shown;

[0020] Figure 3 A schematic structural diagram of a bootstrap capacitor charging circuit of a multi-phase voltage converter according to an embodiment of the present disclosure is shown;

[0021] Figure 4 An exemplary circuit diagram showing a judgment circuit and a latch circuit according to an embodiment of the present disclosure;

[0022] Figure 5 An exemplary circuit diagram of a standby charging circuit according to an embodiment of the present disclosure is shown;

[0023] Figure 6 A schematic structural diagram of another bootstrap capacitor charging circuit of a multi-phase voltage converter according to an embodiment of the present disclosure is shown;

[0024] Figure 7 A schematic diagram showing waveforms of key signals associated with a bootstrap capacitor charging circuit according to an embodiment of the present disclosure is shown;

[0025] Elements in the drawings are schematic and not drawn to scale. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0027] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless otherwise explicitly defined herein. As used herein, a statement that two or more parts are "connected" or "coupled" together shall mean that the parts are joined together either directly or through one or more intermediate components.

[0028] In all embodiments of the present disclosure, since the source and drain of a metal oxide semiconductor (MOS) transistor are symmetrical, and the conduction current directions between the source and drain of an N-type transistor and a P-type transistor are opposite, in the embodiments of the present disclosure, the controlled middle terminal (gate or gate terminal) of the MOS transistor is referred to as the control terminal, and the remaining two terminals of the MOS transistor are referred to as the first terminal and the second terminal, respectively. In addition, terms such as "first" and "second" are only used to distinguish one component (or a portion of a component) from another component (or another portion of a component).

[0029] Figure 2This is an example circuit diagram for charging a conventional bootstrap capacitor. The charging principle is as follows: the chip power supply VIN is connected to a low-dropout linear regulator (LDO), which generates the chip's internal power supply VCC. When the lower power transistor LS is turned on (i.e., LSON = H), the switch node SW is connected to GND through LS, pulling the SW voltage down to GND. At this point, S1 is closed, and VCC is connected to BST through S1. VCC charges BST, biasing it to VCC. When LS is about to turn off, LSON is pulled low, and S1 opens. The next time the upper power transistor HS turns on, BST powers the upper transistor driver circuit (HSD Driver), turning on HS. At this point, SW is connected to VIN through HS, pulling the SW voltage up to VIN. The lower plate of the bootstrap capacitor CBST is connected to SW, raising the upper plate of CBST to a potential of (VIN + VCC), enabling it to power the upper transistor driver circuit when HS is turned on. The charging principle above shows that CBST can be charged each time LS turns on. However, in a multiphase voltage converter, the HS and LS switches of phases in standby mode are both off, and the SW potential is equal to VOUT. If the VOUT voltage is high, VCC cannot charge the higher potential BST, regardless of whether S1 is closed or not. As the standby state increases, the charge on CBST continues to leak, resulting in insufficient power supply to the high-side power transistor driver (HSD Driver), preventing normal operation. The HS cannot turn on immediately, and the transient response performance of the multiphase voltage converter cannot meet the expectations of simultaneous conduction of the high-side power transistors of multiple phases, thus affecting transient response performance.

[0030] In order to solve the problem that the bootstrap capacitor of the standby phase in a multi-phase voltage converter cannot be charged, resulting in the upper power tube being unable to be turned on immediately when the standby state enters the working state, thereby affecting the transient response performance. The embodiment of the present disclosure proposes a bootstrap capacitor charging circuit for the multi-phase voltage converter. The bootstrap capacitor of the standby phase can be charged by the working phase, thereby ensuring that when the standby phase is converted from the standby state to the working state, the bootstrap capacitor has sufficient voltage to drive the upper power tube to turn on in time, thereby improving the transient response performance of the multi-phase voltage converter. The bootstrap capacitor charging circuit of the multi-phase voltage converter disclosed in the present disclosure is described in detail below.

[0031] Figure 3 A schematic block diagram of a bootstrap capacitor charging circuit 100 for a multi-phase voltage converter according to an embodiment of the present disclosure is shown. The bootstrap capacitor charging circuit 100 for a multi-phase voltage converter according to an embodiment of the present disclosure includes: a determination circuit 110 , a latch circuit 120 , and a standby charging circuit 130 .

[0032] The judgment circuit 110 is coupled to both ends of a bootstrap capacitor CBST1. The judgment circuit 110 is configured to determine whether a voltage difference (BST1-SW1) across the bootstrap capacitor CBST1 is greater than or equal to a preset voltage value, and output a judgment result signal BSTUVb1. The bootstrap capacitor CBST1 is a bootstrap capacitor for the standby phase of the multi-phase voltage converter. The preset voltage value is set to ensure that the voltage across the bootstrap capacitor CBST1 is sufficient to power the driver circuit of the upper power transistor when the standby phase transitions from a standby state to an operating state. In this embodiment, if the voltage difference across the bootstrap capacitor CBST1 is greater than or equal to the preset voltage value, the judgment result signal BSTUVb1 is a high-level signal; if the voltage difference across the bootstrap capacitor CBST1 is less than the preset voltage value, the judgment result signal BSTUVb1 is a low-level signal. In addition, it should be noted that the bootstrap capacitor charging circuit 100 in the embodiment of the present disclosure is mainly suitable for phase circuits that are in standby state due to load requirements during the operation of a multi-phase voltage converter. Therefore, the standby phase here does not necessarily refer to the phase that is currently in standby state. All phases that may be in standby state can be used when they are in standby state.

[0033] The latch circuit 120 is coupled to the judgment circuit 110. The latch circuit 120 is configured as an upper power transistor ( Figure 3 HS2 in the figure) is turned off, the judgment result signal BSTUVb1 is latched, and the output signal of the latch circuit 120 is the charging indication signal BSTOK1. The working phase is a phase that always maintains the working state when the multi-phase voltage converter is working, that is, when only one phase circuit needs to be kept working, the phase that is retained is the working phase in the embodiment of the present disclosure. The charging indication signal BSTOK1 is used to indicate whether the bootstrap capacitor CBST1 of the standby phase needs to be charged. The charging indication signal BSTOK1 is a signal output after latching the judgment result signal BSTUVb1, so the polarity of the two is the same. Specifically, when the judgment result signal BSTUVb1 is at a low level, it means that the voltage on the bootstrap capacitor CBST1 is not enough for the upper power tube (the upper power tube HS1 of the standby phase, Figure 3 The bootstrap capacitor CBST1 is powered by the driving circuit of the upper power tube HS1 (not shown), so it needs to be charged. Therefore, when the corresponding charging indication signal BSTOK1 is at a low level, it indicates that CBST1 needs to be charged. When the judgment result signal BSTUVb1 is at a high level, it indicates that the voltage on the bootstrap capacitor CBST1 is sufficient to power the driving circuit of the upper power tube HS1, so it does not need to be charged. Therefore, the corresponding charging indication signal BSTOK1 is at a high level, indicating that CBST1 does not need to be charged.

[0034] Standby charging circuit 130 and latch circuit 120, working phase ( Figure 3The phases corresponding to HS2 and LS2 are shown in the figure. Figure 3 Also shown is an existing charging circuit structure of the bootstrap capacitor CBST2 in the working phase, which is similar to Figure 2 The charging method is the same as in the above example), one end BST1 of the bootstrap capacitor CBST1 is coupled to the standby charging circuit 130, and the standby charging circuit 130 is configured to form a charging path between the working phase and the bootstrap capacitor CBST1, and control whether to charge the bootstrap capacitor CBST1 of the standby phase through the working phase according to the charging indication signal BSTOK1. Specifically, when the charging indication signal BSTOK1 is at a low level, indicating that the bootstrap capacitor CBST1 needs to be charged, the standby charging circuit 130 charges the bootstrap capacitor CBST1 of the standby phase. When the charging indication signal BSTOK1 is at a high level, indicating that the bootstrap capacitor CBST1 does not need to be charged, the standby charging circuit 130 can be controlled not to charge the bootstrap capacitor CBST1 of the standby phase.

[0035] As can be seen from the above description, in the bootstrap capacitor CBST1 charging circuit of the multi-phase voltage converter according to the embodiment of the present disclosure, if the bootstrap capacitor CBST1 in the standby phase cannot be charged, the voltage difference across the bootstrap capacitor CBST1 is detected to determine whether charging is required. If charging is required, the bootstrap capacitor CBST1 in the standby phase is charged from the working phase by establishing an association with the working phase. This ensures that when the standby phase transitions from the standby state to the working state, the bootstrap capacitor CBST1 has sufficient voltage to promptly drive the upper power transistor into conduction, thereby improving the transient response performance of the multi-phase voltage converter.

[0036] Further, such as Figure 4 As shown, the determination circuit 110 includes: a first resistor R1, a second resistor R2, a first transistor M1, a comparator A, and an inverter INV. One end of the first resistor R1 is coupled to one end BST1 of a bootstrap capacitor CBST1, and the other end of the first resistor R1 is coupled to a first electrode of the first transistor M1. A control electrode of the first transistor M1 is coupled to the other end of the bootstrap capacitor CBST1, and the other end of the bootstrap capacitor CBST1 is coupled to a switch node SW1 of a standby phase corresponding to the bootstrap capacitor CBST1 (a node between the upper power transistor HS1 and the lower power transistor LS1 in the phase where CBST1 resides). A second electrode of the first transistor M1 is coupled to one end of the second resistor R2 and a negative input of the comparator A, respectively. The other end of the second resistor R2 is coupled to ground. A positive input of the comparator A is coupled to a preset reference voltage Vref, an output of the comparator A is coupled to the input of the inverter INV, and the output of the comparator A outputs a BSTUV1 signal. The output of the inverter INV serves as the output of the determination circuit 110, outputting a determination result signal BSTUVb1. In addition, in order to reduce static current consumption, the comparator A can also be made to perform comparison only when the upper power tube HS2 is turned on in the working phase.

[0037] Further, such as Figure 4 As shown, the latch circuit 120 includes a latch D0, wherein the data input terminal D of the latch D0 is coupled to the judgment result signal BSTUVb1, the clock pulse input terminal CP of the latch D0 is coupled to the latch trigger signal, the latch trigger signal is the inverted signal HSONb2 of the upper power tube conduction control signal HSON2 in the working phase under the low voltage domain, and the output terminal Q of the latch D0 serves as the output terminal of the latch circuit 120 to output the charging indication signal BSTOK1. The low voltage domain is a voltage region greater than or equal to zero voltage and less than or equal to the power supply voltage VCC. Figure 1 As shown, the control signals (HSON1, LSON1, HSON2, LSON2) output by the multi-phase control circuit (Multi-Phase Controller) are signals in the low-voltage domain.

[0038] Further, such as Figure 5 As shown, the standby charging circuit 130 includes: a capacitor voltage control module 131, a charging capacitor C0, and a charging module 132.

[0039] Among them, the capacitor voltage control module 131 is configured to provide the power supply voltage VCC to one end BST_2C1 of the charging capacitor C0 (i.e., charge the charging capacitor C0) when the charging indication signal BSTOK1 indicates that the bootstrap capacitor CBST1 needs to be charged, and to provide zero voltage to one end BST_2C1 of the charging capacitor C0 (i.e., discharge the charging capacitor C0) when the charging indication signal BSTOK1 indicates that the bootstrap capacitor CBST1 does not need to be charged. The connection and disconnection between the capacitor voltage control module 131 and the charging capacitor C0 is controlled by a first control signal, which is the lower power tube conduction control signal LSON2 of the working phase in the low-voltage domain. The working principle of the capacitor voltage control module 131 is as follows: when the lower power tube LS2 of the working phase is turned on, the corresponding first control signal LSON2 is at a high level, coupling the capacitor voltage control module 131 to one end of the charging capacitor C0. At this time, if the charging indication signal BSTOK1 is at a low level, the power supply voltage VCC is provided to one end of the charging capacitor C0, that is, the power supply voltage VCC is used to charge the charging capacitor C0. If the charging indication signal BSTOK1 is at a high level, zero voltage is provided to one end of the charging capacitor C0, that is, the charging capacitor C0 is discharged. Further, as Figure 5As shown, the capacitor voltage control module 131 includes: a second transistor M2, a third transistor M3, and a first switch S1. The control electrodes of the second transistor M2 and the third transistor M3 are both coupled to the charging indication signal BSTOK1. The first electrode of the second transistor M2 is coupled to the power supply voltage VCC, the first electrode of the third transistor M3 is coupled to the ground terminal, and the second electrodes of the second transistor M2 and the third transistor M3 are both coupled to one end of the first switch S1. The other end of the first switch S1 is coupled to one end BST_2C1 of the charging capacitor C0. The second transistor M2 is a P-type transistor, and the third transistor M3 is an N-type transistor.

[0040] like Figure 5 As shown, the other end of the charging capacitor C0 is coupled to the switch node SW2 of the working phase, and the switch node SW2 is the upper power tube HS2 ( Figure 3 ) and the lower power tube LS2 ( Figure 3 ), the voltage at one end BST_2C1 of the charging capacitor C0 changes with the voltage of the switching node SW2 during the working phase. The voltage of the switching node SW2 during the working phase is different when the lower power transistor LS2 or the upper power transistor HS2 is on. Therefore, when the voltage of the switching node SW2 changes, that is, when the voltage of the other end of the charging capacitor C0 changes, the corresponding voltage at the one end BST_2C1 of the charging capacitor C0 also changes.

[0041] The charging module 132 is configured to charge the bootstrap capacitor CBST1 of the standby phase through the voltage BST_2C1 at one end of the charging capacitor C0. The on-off of the charging module 132 and the charging capacitor C0 is controlled by the second control signal. The second control signal is the inverted signal HSON_SWb2 of the upper power tube conduction control signal HSON2 of the working phase in the high-voltage domain. The high-voltage domain is the upper power tube driver circuit HSD Driver ( Figure 3 The voltage domain where the SW2 and BST2 are located is the voltage domain determined by SW2 and BST2, that is, the range greater than or equal to the voltage of SW2 and less than or equal to the voltage of BST2. Figure 5 As shown, the charging module 132 includes: a fourth transistor M4 and a fifth transistor M5, wherein the control electrode of the fourth transistor M4 is coupled to the second control signal HSON_SWb2, the first electrode of the fourth transistor M4 is coupled to one end BST_2C1 of the charging capacitor C0, the control electrode of the fifth transistor M5 and the first electrode of the fifth transistor M5 are both coupled to one end BST1 of the bootstrap capacitor CBST1 of the front phase, and the second electrode of the fourth transistor M4 is coupled to the second electrode of the fifth transistor M5.

[0042] Combine Figure 3-5The working principle of the bootstrap capacitor charging circuit 100 in the embodiments of the present application is described as follows: As Figure 4 shown, the potential at the other end of R1 is (SW1 + VGS_M1), so the current flowing through R1 is (BST1 - SW1 - VGS_M1) / R1. Since the currents flowing through R1 and R2 are equal, then Vfb = (BST1 - SW1 - VGS_M1)*R2 / R1. The positive input terminal of comparator A is connected to Vref, and the negative input terminal is connected to Vfb. If Vref is greater than Vfb, it is obtained that BST1 - SW1 < Vref*R1 / R2 + VGS_M1, and Vref*R1 / R2 + VGS_M1 is the aforementioned preset voltage value, that is, the voltage difference BST1 - SW1 across the bootstrap capacitor CBST1 in the standby phase is less than the preset voltage value, and CBST1 needs to be charged. At this time, the output BSTUV1 of comparator A is at a high level, and the BSTUVb1 obtained after passing through INV is at a low level; if Vref is less than or equal to Vfb, then it is obtained that the voltage difference BST1 - SW1 across the bootstrap capacitor CBST1 in the standby phase is greater than or equal to the preset voltage value, and CBST1 does not need to be charged. At this time, the output BSTUV1 of comparator A is at a low level, and the BSTUVb1 obtained after passing through INV is at a high level. BSTUVb1 is input to the D terminal of the latch. At the moment when the upper power transistor HS2 in each working phase is turned off, that is, at the rising edge of HSONb2, BSTUVb1 is stored in the latch D0, and the latch outputs a charging indication signal BSTOK1. D0 is updated and output when the upper power transistor HS2 in each working phase is turned off. From the above analysis, it can be seen that if the voltage of (BST1 - SW1) is lower than the preset voltage value, then BSTOK1 = L (low level); otherwise, BSTOK1 = H (high level).

[0043] The first terminal (source) of M2 is connected to the chip's internal power supply VCC. When BSTOK1 = L, M2 is on; otherwise, it is off. The first terminal (source) of M3 is connected to GND (zero voltage / ground). When BSTOK1 = L, M3 is off; otherwise, it is on. When the lower power transistor LS2 in the working phase is on, that is, when LSON2 is high, SW2 is pulled down to GND, and S1 is turned on. At this time, if BSTOK1 = L, C0's upper plate BST_2C1 is charged to VCC potential by VCC; if BSTOK1 = H, C0 is discharged to GND potential by GND. When the lower power transistor LS2 in the working phase is off, that is, when LSON2 is low, S1 is turned off. When the upper power transistor HS2 in the working phase is on, SW2 is pulled up to VIN potential, and BST_2C1 is also pulled high. If BSTOK1 = L when LS2 was last turned on, BST_2C1 is raised to (VIN + VCC). At this point, M4 is turned on, and BST_2C1 charges BST1 through the channels of M4, M5, and their body diodes. The maximum steady-state voltage supported by BST1 is (VIN + VCC - VGS_M5). If BSTOK1 = H when LS2 was last turned on, BST_2C1 reaches VIN. Since M4's gate (control electrode) is also at VIN at this point, M4 is turned off, and C0 does not charge BST1. When the standby phase circuit switches to operation, because MP5's gate (control electrode) and source (first electrode) are connected, even if BST1 is raised, M5 remains off, preventing leakage into BST_2C1.

[0044] Further, such as Figure 6 As shown, the bootstrap capacitor charging circuit 100 further includes: a non-standby charging circuit 140, which is configured to charge the bootstrap capacitor through the power supply voltage when the lower power tube of the standby phase is turned on after the standby phase is converted from the standby state to the working state. Figure 3 The capacitor charging circuit 100 in the embodiment mainly charges the bootstrap capacitor of the standby phase circuit through the working phase circuit. The existing bootstrap capacitor charging circuit is still required for the startup or normal operation of the standby phase. Figure 6 The non-standby charging circuit 140 is used for starting the standby phase or normal operation. Figure 6As shown, the non-standby charging circuit 140 includes a low-dropout linear regulator LDO and a second switch S2, wherein the input end of the low-dropout linear regulator LDO is coupled to the input voltage VIN (chip power supply) of the multi-phase voltage converter, and the output end of the low-dropout linear regulator LDO outputs VCC and is coupled to one end of the second switch S2; the other end of the second switch S2 is coupled to one end BST1 of the bootstrap capacitor CBST1, and the other end of the bootstrap capacitor CBST1 is coupled to the switch node SW1 of the corresponding phase of the bootstrap capacitor CBST1; the switching of the second switch S2 is controlled by a third control signal, which is the conduction control signal LSON1 of the lower power transistor LS1 of the corresponding phase of the bootstrap capacitor CBST1. Figure 6 For the circuit principle of the non-standby charging circuit 140, see Figure 2 Circuit description.

[0045] In practical applications, the bootstrap capacitor CBST1 is usually an on-chip capacitor with a relatively large capacitance value, or even an off-chip capacitor with a very large capacitance value. C0 is an on-chip capacitor, and its capacitance value is usually relatively small due to chip area limitations. The capacitance value of C0 in the embodiment of the present disclosure only needs to support the leakage consumption of BST1 in the standby state, and has no direct relationship with the capacitance value of CBST1. If the leakage current ILKG of BST1 is considered, it should include the current of the R1, M1, and R2 branches, and the working cycle of the working phase circuit is set to TSW, then the highest potential of BST1 supported in stability in the embodiment of the present disclosure is VBST1 = VIN + VCC - VGS_M5 - ILKG * TSW / C0.

[0046] In order to further illustrate the effect of the bootstrap capacitor charging circuit 100 of the multi-phase voltage converter in the embodiment of the present disclosure, Figure 7 The waveform diagrams of the key signals SW1, SW2, HSON2, LSON2, BSTOK1, and the voltage difference between HSON_SWb2 and SW2 (HSON_SWb2-SW2), the voltage difference between BST_2C1 and SW2 (BST_2C1-SW2), and the voltage difference between BST1 and SW1 (BST1-SW1) are shown. It should be noted that since HSON_SWb2 and BST_2C1 are both signals in the high-voltage domain (SW2, BST2), Figure 7 In the figure, the voltage values ​​relative to SW2 (zero potential in the high voltage domain) are shown. Figure 7It can also be seen that SW2 is pulled up to the VIN potential when HS2 is turned on. If the BSTOK1 signal is low, when LS2 is turned on next time, SW2 is pulled down to the GND potential, and VCC pulls BST_2C1 up to the VCC potential. LS2 is turned off, and when HS2 is turned on next time, SW2 is pulled up to the VIN potential, and BST_2C1 is raised to the (VIN+VCC) potential by C0. At this time, HSON_SWb2 is pulled low, and BST_2C1 charges BST2, and the two charges are completed (it should be noted that although the potentials of BST_2C1 are different, Figure 7 The figure shows the difference between BST_2C1 and SW2. The difference between BST_2C1 and SW2 remains unchanged after two charges. If the potential of (BST1-SW1) rises and exceeds the preset voltage value, BSTOK1 will be pulled high and BST1 will not be charged.

[0047] The embodiment of the present disclosure further provides a multi-phase voltage converter, the multi-phase voltage converter including n phases, n being a positive integer greater than or equal to 2, wherein one phase among the n phases always remains in an operating state when the multi-phase voltage converter is operating, and the other n-1 phases switch between a standby state and an operating state according to the load of the multi-phase voltage converter, and for each phase of the other n-1 phases, including the above Figure 3-6 The bootstrap capacitor charging circuit 100 of the multi-phase voltage converter according to any one of the corresponding embodiments. One phase that always maintains the working state is still charged by the existing bootstrap capacitor charging method (for example, Figure 2 The multiphase voltage converter of the embodiment of the present disclosure can be charged by the working phase while in standby mode, so that the power transistors on each phase can be turned on promptly when the phase switches from standby to working mode, thereby improving the transient response performance of the multiphase voltage converter. The multiphase voltage converter of the embodiment of the present disclosure can be a multiphase buck regulator or a multiphase boost converter.

[0048] In summary, the bootstrap capacitor charging circuit and the multi-phase voltage converter of the multi-phase voltage converter in the embodiment of the present disclosure enable the standby phase to be charged through the working phase when in standby mode, so that the power tube on it can be turned on in time when it switches from standby mode to working mode, thereby improving the transient response performance of the multi-phase voltage converter.

[0049] Unless the context clearly indicates otherwise, as used herein and in the appended claims, the singular includes the plural, and vice versa. Thus, when referring to the singular, the plural of the corresponding term is generally included. Similarly, the words "include" and "comprising" are to be interpreted as inclusive rather than exclusive. Likewise, the terms "include" and "or" should be interpreted as inclusive unless such interpretation is expressly prohibited herein. Where the term "example" is used herein, particularly when it follows a group of terms, "example" is merely exemplary and illustrative and should not be considered exclusive or comprehensive.

[0050] Further aspects and scope of adaptability become apparent from the description provided herein. It should be understood that various aspects of the present disclosure can be implemented individually or in combination with one or more other aspects. It should also be understood that the description and specific embodiments herein are intended to be illustrative only and are not intended to limit the scope of the present disclosure.

[0051] Several embodiments of the present disclosure have been described in detail above, but it is obvious that those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. The scope of protection of the present disclosure is defined by the appended claims.

Claims

1. A bootstrap capacitor charging circuit for a multi-phase voltage converter, characterized in that: The bootstrap capacitor charging circuit includes: a judgment circuit, a latch circuit, and a standby charging circuit. The judgment circuit is coupled to both ends of a bootstrap capacitor, and is configured to judge whether a voltage difference between both ends of the bootstrap capacitor is greater than or equal to a preset voltage value, and output a judgment result signal. The bootstrap capacitor is a bootstrap capacitor of a standby phase in a multi-phase voltage converter. The latch circuit is coupled to the judgment circuit, and is configured to latch the judgment result signal when the upper power transistor of the working phase in the multi-phase voltage converter is turned off. The output signal of the latch circuit is a charging indication signal. The working phase is a phase that always remains in a working state when the multi-phase voltage converter is working. The standby charging circuit is coupled to the latch circuit, the working phase, and one end of the bootstrap capacitor. The standby charging circuit is configured to form a charging path between the working phase and the bootstrap capacitor, and to control whether to charge the bootstrap capacitor of the standby phase through the working phase according to a charging indication signal.

2. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 1, wherein: The standby charging circuit includes: a capacitor voltage control module, a charging capacitor, and a charging module. Wherein, the capacitor voltage control module is configured to provide a power supply voltage to one end of the charging capacitor when the charging indication signal indicates that the bootstrap capacitor needs to be charged, and to provide a zero voltage to one end of the charging capacitor when the charging indication signal indicates that the bootstrap capacitor does not need to be charged; the on-off connection between the capacitor voltage control module and the charging capacitor is controlled by a first control signal, and the first control signal is a lower power tube conduction control signal of the working phase in the low-voltage domain, and the low-voltage domain is a voltage region greater than or equal to zero voltage and less than or equal to the power supply voltage; The other end of the charging capacitor is coupled to the switch node of the working phase, where the switch node is a node between the upper power tube and the lower power tube, and the voltage at one end of the charging capacitor changes with the voltage of the switch node of the working phase; The charging module is configured to charge the bootstrap capacitor of the standby phase through the voltage at one end of the charging capacitor. The on and off of the charging module and the charging capacitor are controlled by a second control signal. The second control signal is an inverted signal of the upper power tube conduction control signal of the working phase in the high-voltage domain. The high-voltage domain is the voltage domain where the upper power tube drive circuit of the working phase is located.

3. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 1, wherein: The judgment circuit includes: a first resistor, a second resistor, a first transistor, a comparator, and an inverter. Wherein, one end of the first resistor is coupled to one end of the bootstrap capacitor, and the other end of the first resistor is coupled to the first electrode of the first transistor; The control electrode of the first transistor is coupled to the other end of the bootstrap capacitor, the other end of the bootstrap capacitor is coupled to the switch node of the standby phase corresponding to the bootstrap capacitor, and the second electrode of the first transistor is coupled to one end of the second resistor and the negative input terminal of the comparator respectively; The other end of the second resistor is coupled to the ground; The positive input terminal of the comparator is coupled to a preset reference voltage, and the output terminal of the comparator is coupled to the input terminal of the inverter; The output end of the inverter serves as the output end of the judgment circuit to output the judgment result signal.

4. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 1, wherein: The latch circuit includes a latch, In which, the data input end of the latch is coupled to the judgment result signal, the clock pulse input end of the latch is coupled to the latch trigger signal, the latch trigger signal is the inverted signal of the upper power tube conduction control signal of the working phase in the low voltage domain, and the output end of the latch serves as the output end of the latch circuit to output the charging indication signal.

5. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 2, wherein: The capacitor voltage control module includes: a second transistor, a third transistor, and a first switch. wherein the control electrodes of the second transistor and the third transistor are both coupled to the charging indication signal, the first electrode of the second transistor is coupled to a power supply voltage, the first electrode of the third transistor is coupled to a ground terminal, and the second electrodes of the second transistor and the third transistor are both coupled to one terminal of the first switch; The other end of the first switch is coupled to one end of the charging capacitor.

6. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 2, wherein: The charging module includes: a fourth transistor and a fifth transistor, In which, the control electrode of the fourth transistor is coupled to the second control signal, the first electrode of the fourth transistor is coupled to one end of the charging capacitor, the control electrode of the fifth transistor and the first electrode of the fifth transistor are both coupled to one end of the bootstrap capacitor of the standby phase, and the second electrode of the fourth transistor is coupled to the second electrode of the fifth transistor.

7. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 5, wherein: The second transistor is a P-type transistor, and the third transistor is an N-type transistor.

8. The bootstrap capacitor charging circuit of the multi-phase voltage converter according to claim 3, wherein: The comparator performs comparison when the upper power tube is turned on in the working phase.

9. The bootstrap capacitor charging circuit of a multi-phase voltage converter according to claim 1, wherein: The bootstrap capacitor charging circuit further includes: a non-standby charging circuit configured to charge the bootstrap capacitor through a power supply voltage when the lower power tube of the standby phase is turned on after the standby phase is started or converted from the standby state to the working state.

10. A multi-phase voltage converter, comprising n phases, where n is a positive integer greater than or equal to 2, wherein: One of the n phases always remains in an operating state when the multi-phase voltage converter is operating, and the other n-1 phases switch between a standby state and an operating state according to the load of the multi-phase voltage converter. It is characterized in that for each of the other n-1 phases, it includes a bootstrap capacitor charging circuit for the multi-phase voltage converter according to any one of claims 1 to 9.

Images