Fast transient response Buck converter based on AOT control

Abstract

The invention discloses a fast transient response Buck converter based on AOT control, which is compatible with the advantages of current mode control and AOT control, and is characterized in that an error amplifier is added in a negative feedback control loop, so that the precision of output voltage is improved, a current loop is stable, and the series resistance value of an output capacitor is not specifically limited; the change rate of the switching frequency in heavy load is reduced by using the improved self-adaptive turn-on time module, and the change of the switching frequency under different load current conditions is ensured to be small. The transient enhancement module is used for judging the output voltage, it is ensured that when the load current suddenly changes, the output voltage is fast and stable, overshoot and undershoot are reduced, and therefore the overall stability and reliability are improved. The sleep detection module Sleep is used for detecting a switching tube driving signal VCOMP so as to control the Buck converter to enter a dormant state, and therefore the purposes of reducing power consumption and improving efficiency are achieved.

Description

Technical Field

[0001] The invention belongs to the field of DC-DC converters, and in particular relates to a fast transient response Buck converter based on AOT control. Background Art

[0002] A DC-DC converter is a power management chip that converts power energy into different output voltages or different output currents. Smart phones, laptops, car chargers, portable smart devices, etc., which are now widely used, are inseparable from the role of DC-DC converters. Among DC / DC switching power supplies, buck converters are widely used in the electronics industry. Since electronic devices have multiple working states such as sleep mode and working mode, during the mode switching process, the load needs to draw different and frequently changing currents from the power supply, which requires the Buck converter to have a fast transient response speed. Otherwise, the overshoot voltage or excessive drop voltage may cause problems such as abnormal operation of the equipment.

[0003] In order to enhance load transient response and work efficiency, many control methods have been proposed. Among them, V 2 The Buck converter controlled by PWM consists of two control loops: feed-forward loop (FFL) and regulation loop (RL). FFL transmits the high-frequency signal of the inductor current to the PWM modulator. Therefore, V 2 Control can quickly recover undershoot / overshoot voltage when load current changes. However, conventional V 2 Control due to the equivalent series resistance R ESR Larger, larger ripple. RBCOT control has the advantages of automatic frequency reduction under light load and high efficiency. At the same time, the design is simplified by not requiring EA and compensation network. However, this will also bring about the problem of DC offset. The DC value of the output voltage cannot be determined, and the accuracy is very low, so RBCOT control requires the design of a DC offset elimination circuit. In addition, because COT belongs to variable frequency control, the electromagnetic interference EMI problem is more serious than PWM control. Usually, an improved AOT control is used to adjust the on-time and constant switching frequency. CMCOT control is current mode constant on-time control with two feedback loops, voltage and current. The current feedback control loop introduces information related to the inductor current, which makes the Buck converter controlled by CMCOT have an equivalent series resistance R ESR The error amplifier in the feedback loop can improve the output voltage accuracy. By extending the adaptive on-time T ON , which speeds up transient response, but requires additional off-chip capacitors and resistors. Adaptive, quasi-adaptive T ONCurrent mode control can improve transient response, but this method cannot keep the switching frequency constant. To achieve a COT converter with constant switching frequency and fast transient response, the LCC circuit consumes more power due to sensing the inductor current, and V SENSE It is easily affected by PVT changes. The two-level window control circuit and phase-locked loop (PLL) method can achieve a fixed switching frequency. However, due to limited bandwidth. PLL limits the load transient response. The operation of the adaptive on-time controller with a frequency-locked loop (FLL) simplifies the system architecture and shortens the transient response, but the output voltage ripple and regulation performance are reduced.

[0004] Although the industry has proposed a variety of control strategies to enhance the load transient response and efficiency of Buck converters, these methods often come with their own problems. 2 The Buck converter controlled by the PWM control can quickly restore the voltage when the load current changes, reducing undershoot or overshoot through the design of the feedforward loop and the regulation loop. However, this control method has a large equivalent series resistance (R ESR ) causes large ripple, affecting the stability of the output voltage. On the other hand, although the RBCOT control strategy has the advantages of automatically reducing the frequency when lightly loaded to improve efficiency and simplifying the design by eliminating the need for an error amplifier and compensation network, it also brings about the problem of DC offset. This results in the inability to determine the DC value of the output voltage, and the accuracy is significantly reduced. Therefore, a DC offset elimination circuit must be designed to compensate for this defect. In addition, since COT control belongs to variable frequency control, its electromagnetic interference (EMI) problem is more serious than that of PWM control. In order to alleviate this problem, an improved AOT control is often used to adjust the on-time to keep the switching frequency constant, but the traditional AOT module will also change with changes in input and output conditions. At the same time, adaptive and quasi-adaptive T ON Although current mode control can improve transient response, it cannot keep the switching frequency constant, which may affect the stability and efficiency of the system. In the pursuit of constant switching frequency and fast transient response, some methods such as LCC circuits can achieve these goals, but they consume more power due to sensing the inductor current, and V SENSE It is easily affected by process, voltage and temperature changes (PVT). Although the two-level window control circuit and phase-locked loop (PLL) method can achieve a fixed switching frequency, the PLL will limit the load transient response due to limited bandwidth. Although the adaptive on-time controller with frequency-locked loop (FLL) simplifies the system architecture and shortens the transient response, it also reduces the ripple and regulation performance of the output voltage. Therefore, the Buck converter still faces many technical challenges and requires faster transient response, higher stability and better efficiency. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a fast transient response Buck converter based on AOT control. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] The present invention provides a fast transient response Buck converter based on AOT control, comprising:

[0007] Comparison signal selection module, error amplifier EA, PWM comparator, adaptive on-time module AOT, output module, transient enhancement module and sleep detection module Sleep; Among them,

[0008] The comparison signal selection module is used to select a signal according to the reference voltage V under the control of the Sign signal output by the transient enhancement module. REF and soft-start voltage V SS Output the signal to be compared;

[0009] The error amplifier EA is used to convert the feedback signal V corresponding to the output voltage of the Buck converter FB Compare with the signal to be compared, and output the error amplified signal V EA ;

[0010] The PWM comparator is used to amplify the error signal V EA The ripple voltage V corresponding to the inductor in the Buck converter F Compare and output the switch tube drive signal V COMP ;

[0011] The adaptive on-time module AOT is used to adjust the steady-state voltage V corresponding to the switch tube in the output module. SW The conduction time T corresponding to the conduction signal ON ;

[0012] The output module is used to drive the switch tube according to the signal V COMP Control the conduction of its own switch tube, according to the conduction time T ON Generate a rectifier tube drive signal to control the conduction of its own rectifier tube to generate a periodic output voltage; the output module uses an internal adaptive dead time circuit to prevent the rectifier tube and the switch tube from being turned on at the same time;

[0013] The transient enhancement module is used to output a Sign signal to the comparison signal selection module when the load of the Buck converter jumps and the output voltage of the Buck converter overshoots or undershoots to a preset threshold;

[0014] The sleep detection module Sleep is used to drive the switch tube signal V COMP Detection is performed to determine the switch tube drive signal V COMP Whether the preset conditions are met, if so, a sleep signal is output to control the Buck converter to enter a sleep state.

[0015] In one embodiment of the present invention, the comparison signal selection module includes:

[0016] Reference circuit BG, soft start circuit Soft Start and selector module.

[0017] In one embodiment of the present invention, the comparison signal selection module, under the control of the Sign signal output by the transient enhancement module, generates a signal according to the reference voltage V REF and soft-start voltage V SS Output the signal to be compared, including:

[0018] The reference circuit BG generates a reference voltage V REF ;

[0019] The soft start circuit Soft Start generates a soft start voltage V SS ;

[0020] The selector module is controlled by the Sign signal output by the transient enhancement module according to the reference voltage V REF and the soft-start voltage V SS Output the signal to be compared.

[0021] In one embodiment of the present invention, the adaptive on-time module AOT comprises:

[0022] VI converter, inverter, MOS tube M1, capacitor C1, resistor R1, resistor R2, resistor R3, filter circuit, first two-choice selector, second two-choice selector and first comparator COMP1; wherein,

[0023] The input terminal of the VI converter is connected to the power supply voltage V DD , a first output terminal is connected to the inverting input terminal of the first comparator COMP1, and a second output terminal is connected to the first terminal of the capacitor C1;

[0024] The input end of the inverter is connected to the trigger signal NG1 corresponding to the switch tube, and the output end is connected to the gate of the MOS tube M1;

[0025] The source of the MOS tube M1 is grounded, and the drain is connected to the first end of the capacitor C1;

[0026] The first end of the capacitor C1 is connected to the inverting input end of the first comparator COMP1, and the second end is connected to the source of the MOS transistor M1;

[0027] The first end of the resistor R1 is connected to the steady-state voltage V corresponding to the switch tube SW , the second end is connected to the first end of the capacitor C1;

[0028] The first end of the resistor R2 is connected to the first end of the resistor R1, and the second end is connected to the first end of the resistor R3;

[0029] The first end of the resistor R3 is connected to the input end of the filter circuit, and the second end is grounded;

[0030] The output end of the filter circuit is connected to the first input end of the second two-to-one selector, and the ground end is grounded;

[0031] The first input terminal of the first two-to-one selector is connected to a preset first voltage V L , the second input end is connected to the first input end of the second two-selector, the control end is connected to the Sign signal output by the transient enhancement module, and the output end is connected to the output end of the second two-selector;

[0032] The second input terminal of the second two-to-one selector is connected to a preset second voltage V H , the output end is connected to the non-inverting input end of the first comparator COMP1;

[0033] The output terminal of the first comparator COMP1 outputs the conduction time T ON .

[0034] In one embodiment of the present invention, a VI converter comprises:

[0035] Current Source I SS , MOS tube M2, MOS tube M3, transistor Q1, transistor Q2 and resistor R6; wherein,

[0036] Current Source I SS The first end is connected to the source of the MOS tube M3, and the second end is connected to the base of the transistor Q1;

[0037] The source of the MOS tube M2 is connected to the source of the MOS tube M3, the gate is connected to the gate of the MOS tube M3, and the drain serves as the first output end of the VI converter;

[0038] The source of the MOS tube M3 is connected to the power supply voltage V DD , the gate is connected to its own drain, and the drain is connected to the collector of the transistor Q1;

[0039] The emitter of the transistor Q1 is connected to the first end of the resistor R6;

[0040] The collector of the transistor Q2 is connected to the second end of the resistor R6, the base serves as the second output end of the VI converter, and the emitter is connected to the base of the transistor Q1;

[0041] A second end of the resistor R6 is grounded.

[0042] In one embodiment of the present invention, the filter circuit comprises:

[0043] Resistor R4, resistor R5, capacitor C2 and capacitor C3; wherein,

[0044] The first end of the resistor R4 serves as the input end of the filter circuit, and the second end is connected to the first end of the resistor R5;

[0045] The first end of the resistor R5 is connected to the first end of the capacitor C2, and the second end is connected to the first end of the capacitor C3;

[0046] The second end of the capacitor C2 serves as the grounding end of the filter circuit;

[0047] The first end of the capacitor C3 serves as the output end of the filter circuit, and the second end is connected to the second end of the capacitor C2.

[0048] In one embodiment of the present invention, the on-time T generated by the adaptive on-time module AOT ON The expression is as follows:

[0049]

[0050] Wherein, R2 represents the resistance value of resistor R2, R3 represents the resistance value of resistor R3, C1 represents the capacitance value of capacitor C1, R1 represents the resistance value of resistor R1, D actual Indicates the actual duty cycle of the Buck converter.

[0051] In one embodiment of the present invention, the transient enhancement module includes:

[0052] Resistor R7, capacitor C4, second comparator COMP2 and third comparator COMP3; wherein,

[0053] The first end of the resistor R7 is connected to the output voltage V of the Buck converter. OUT , the second end is connected to the first end of the capacitor C4;

[0054] The second end of the capacitor C4 is grounded;

[0055] The non-inverting input terminal of the second comparator COMP2 is connected to the first end of the capacitor C4, the inverting input terminal is connected to the non-inverting input terminal of the third comparator COMP3, and the output terminal outputs the signal Sign1;

[0056] The inverting input terminal of the third comparator COMP3 is connected to the non-inverting input terminal of the second comparator COMP2, and the output terminal outputs a signal Sign2;

[0057] The signal Sign1 and the signal Sign2 constitute a Sign signal.

[0058] In one embodiment of the present invention, the sleep detection module Sleep includes:

[0059] The first inverter, the MOS tube MP1, the MOS tube MP2, the MOS tube MP3, the MOS tube MP4, the MOS tube MN1, the MOS tube MN2, the MOS tube MN3, the MOS tube MN4, the current source I SS1 and capacitor C SS ;in,

[0060] The input end of the first inverter is connected to the switch tube drive signal V COMP , the output end is connected to the gate of the MOS tube MP1;

[0061] The source of the MOS tube MP1 is connected to the current source I SS1 The output end of the transistor is connected to the drain of the MOS transistor MN1;

[0062] The source of the MOS tube MP2 is connected to the power supply voltage V DD , a gate electrode is connected to the gate electrode of the MOS tube MP3, and a drain electrode is connected to the source electrode of the MOS tube MP3;

[0063] The source of the MOS transistor MP3 is connected to the source of the MOS transistor MP4, the gate is connected to the drain of the MOS transistor MN1, and the drain is connected to the drain of the MOS transistor MN2;

[0064] The gate of the MOS transistor MP4 serves as the output end of the sleep detection module Sleep, and the drain is connected to the source of the MOS transistor MN3;

[0065] The source of the MOS tube MN1 and the capacitor C SS The second end is connected to the gate of the MOS tube MP1, the drain is connected to the capacitor C SS A first end is connected;

[0066] The source of the MOS transistor MN2 is connected to the drain of the MOS transistor MN3, and the gate is connected to the capacitor C SSThe first end of the MOS tube MP4 is connected to the drain electrode thereof, and the drain electrode is connected to the gate electrode of the MOS tube MP4;

[0067] The source of the MOS tube MN3 is grounded, and the gate is connected to the capacitor C SS The first end of the MOS tube MN4 is connected to the drain of the MOS tube MN4;

[0068] The gate of the MOS transistor MN4 is connected to the gate of the MOS transistor MP4, and the drain is connected to the source of the MOS transistor MP2;

[0069] The current source I SS1 The input end is connected to the source of the MOS tube MP2;

[0070] The capacitor C SS The second end is connected to the source of the MOS tube MN3.

[0071] Beneficial effects of the present invention:

[0072] The solution provided by the present invention combines the advantages of current mode control and AOT control. By using the output voltage of the Buck converter as the negative feedback voltage and adding an error amplifier in the negative feedback control loop, the accuracy of the output voltage is improved, the current loop is stable, and the series resistance R of the output capacitor is reduced. ESR There is no specific restriction; the improved adaptive on-time module is used to reduce the rate of change of the switching frequency under heavy load, ensuring that the switching frequency changes less under different load current conditions. The transient enhancement module is used to judge the output voltage to ensure that when the load current changes suddenly, the output voltage can be quickly stabilized, reducing overshoot and undershoot, thereby improving the overall stability and reliability; the sleep detection module is used to detect the switch tube drive signal V COMP Detection is performed to control the Buck converter to enter a sleep state, thereby reducing power consumption and improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 A schematic diagram of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention;

[0074] Figure 2 A schematic diagram of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention;

[0075] Figure 3 A schematic diagram of the structure of an adaptive on-time module AOT in a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention;

[0076] Figure 4A schematic diagram of the structure of a transient enhancement module in a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention;

[0077] Figure 5 A schematic diagram of the structure of a sleep detection module Sleep in a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention;

[0078] Figure 6 An overall simulation diagram of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention;

[0079] Figure 7 A waveform diagram of key signals of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention when in a steady state;

[0080] Figure 8 A comparison diagram of the switching cycle of the switch-on signal corresponding to the switch tube in a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention under different load currents;

[0081] Fig. 9 A comparison diagram of the output voltage and inductor current waveforms of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention when the load current jumps from heavy load to light load with and without a transient enhancement module;

[0082] Fig.10 A comparison diagram of the output voltage and inductor current waveforms of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention when the load current jumps from light load to heavy load with and without a transient enhancement module;

[0083] Fig.11 A waveform diagram of sleep module detection of a fast transient response Buck converter based on AOT control provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0084] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0085] The embodiment of the present invention provides a fast transient response Buck converter based on AOT control, such as Figure 1 As shown, it may include:

[0086] Comparison signal selection module, error amplifier EA, PWM comparator, adaptive on-time module AOT, output module, transient enhancement module and sleep detection module Sleep; Among them,

[0087] The comparison signal selection module is used to control the Sign signal output by the transient enhancement module according to the reference voltage V REF and soft-start voltage V SS Output the signal to be compared;

[0088] The error amplifier EA is used to convert the feedback signal V corresponding to the output voltage of the Buck converter FB Compare with the signal to be compared and output the error amplified signal V EA ;

[0089] PWM comparator is used to amplify the error signal V EA The ripple voltage V corresponding to the inductor in the Buck converter F Compare and output the switch tube drive signal V COMP ;

[0090] The adaptive on-time module AOT is used to adjust the steady-state voltage V corresponding to the switch tube in the output module. SW The conduction time T corresponding to the conduction signal ON ;

[0091] Output module, used to drive the switch tube signal V COMP Control the conduction of its own switch tube, according to the conduction time T ON Generate a rectifier tube drive signal to control the conduction of its own rectifier tube to generate a periodic output voltage; the output module uses the internal adaptive dead time circuit to prevent the rectifier tube and the switch tube from being turned on at the same time;

[0092] The transient enhancement module is used to output a Sign signal to the comparison signal selection module when the output voltage of the Buck converter surges or undershoots to a preset threshold value when the load of the Buck converter jumps;

[0093] The sleep detection module Sleep is used to drive the switch tube signal V COMP Detect and determine the switch tube drive signal V COMP Whether the preset conditions are met, if so, a sleep signal is output to control the Buck converter to enter a sleep state.

[0094] The present invention aims to propose a high-performance Buck converter, which adopts a ripple-based AOT control method to achieve a fast load transient response, optimizes efficiency through an adaptive dead time circuit, and automatically shuts down unnecessary modules under extremely light load conditions to further improve the overall efficiency.

[0095] In modern electronic systems, the load current changes more and more frequently, which puts higher requirements on the transient response of the Buck converter. It is necessary to achieve a faster load transient response to ensure that the output voltage can quickly stabilize when the load current changes suddenly, reduce overshoot and undershoot, and thus improve the stability and reliability of the entire system. The switching frequency of the AOT control method does not change with the input and output voltages, but due to the on-resistance of the MOS tube and the parasitic resistance of the inductor, its switching frequency will change with the load current, resulting in an unstable system frequency and EMI problems. When the load is in an extremely light load state, the output power of the system is very small, and the control circuit continues to consume energy, resulting in unnecessary power consumption. By detecting the load current, it enters a low power consumption state when the load is extremely light, thereby reducing power consumption and improving efficiency.

[0096] Figure 2 A schematic structural diagram of a fast transient response Buck converter based on AOT control provided in an embodiment of the present invention is provided. For ease of understanding, each module of the Buck converter proposed in an embodiment of the present invention is introduced separately below.

[0097] Comparison signal selection module

[0098] Compare signal selection modules, such as Figure 2 As shown, it may include:

[0099] Reference circuit BG, soft start circuit Soft Start and selector module.

[0100] The comparison signal selection module, under the control of the Sign signal output by the transient enhancement module, REF and soft-start voltage V SS The output signals to be compared may include:

[0101] The reference circuit BG generates a reference voltage V REF ;

[0102] The soft start circuit Soft Start generates a soft start voltage V SS ;

[0103] The selector module is controlled by the Sign signal output by the transient enhancement module and generates a signal based on the reference voltage V REF and soft-start voltage V SS Output the signal to be compared.

[0104] Specifically, the reference circuit BG can generate a reference voltage V of 0.6V. REFThe soft start circuit Soft Start can avoid surge current and output voltage overshoot during the system startup process, and can make the output voltage rise gradually. The selector module can include a two-stage selector. When the circuit just starts working, the first-stage selector in the selector module can be used to select the voltage V generated by the soft start circuit Soft Start. SS Alternative reference voltage V REF , so that the input voltage can rise slowly, then the second-stage selector in the selector module selects and outputs the corresponding voltage as the signal to be compared according to the Sign signal output by the transient enhancement module; wherein the voltage V REF_LH Including a preset first reference voltage V REF_L and a preset second reference voltage V REF_H , can be selected to be less than the reference voltage V REF The voltage is used as the preset first reference voltage V REF_L , choose a voltage greater than the reference voltage V REF The voltage is used as the preset second reference voltage V REF_H When the load current of the Buck converter changes suddenly and the Buck converter changes from light load to heavy load, the preset second reference voltage V REF_H As the signal to be compared, when the Buck converter changes from light load to heavy load, the preset first reference voltage V REF_L As the signal to be compared, the signal output by the first-level selector is selected as the signal to be compared during the remaining time. Figure 2 The structure diagram is just an exemplary one. For the specific structure of the second-stage selector in the selector module, please refer to the part that specifically introduces the transient enhancement module below.

[0105] Error Amplifier EA

[0106] The error amplifier EA is used to convert the feedback signal V corresponding to the output voltage of the Buck converter FB Compare with the signal to be compared and output the error amplified signal V EA .

[0107] Amplify the error signal V EA As the reference signal for the PWM comparator.

[0108] PWM Comparator

[0109] PWM comparator is used to amplify the error signal V EA The ripple voltage V corresponding to the inductor in the Buck converter F Compare and output the switch tube drive signal V COMP .

[0110] It can be understood that the ripple voltage V corresponding to the inductor FThe voltage converted from the current flowing through the inductor in the Buck converter.

[0111] Adaptive On Time Module AOT

[0112] Adaptive on-time module AOT, such as Figure 3 As shown, it may include:

[0113] VI converter, inverter, MOS tube M1, capacitor C1, resistor R1, resistor R2, resistor R3, filter circuit, first two-choice selector, second two-choice selector and first comparator COMP1; wherein,

[0114] The input of the VI converter is connected to the power supply voltage V DD , the first output terminal is connected to the inverting input terminal of the first comparator COMP1, and the second output terminal is connected to the first terminal of the capacitor C1;

[0115] The input end of the inverter is connected to the trigger signal NG1 corresponding to the switch tube, and the output end is connected to the gate of the MOS tube M1;

[0116] The source of the MOS tube M1 is grounded, and the drain is connected to the first end of the capacitor C1;

[0117] A first end of the capacitor C1 is connected to the inverting input end of the first comparator COMP1, and a second end of the capacitor C1 is connected to the source of the MOS tube M1;

[0118] The first end of the resistor R1 is connected to the steady-state voltage V corresponding to the switch tube. SW , the second end is connected to the first end of the capacitor C1;

[0119] The first end of the resistor R2 is connected to the first end of the resistor R1, and the second end is connected to the first end of the resistor R3;

[0120] The first end of the resistor R3 is connected to the input end of the filter circuit, and the second end is grounded;

[0121] The output end of the filter circuit is connected to the first input end of the second two-to-one selector, and the ground end is grounded;

[0122] The first input terminal of the first two-to-one selector is connected to a preset first voltage V L , the second input end is connected to the first input end of the second two-choose-one selector, the control end is connected to the Sign signal output by the transient enhancement module, and the output end is connected to the output end of the second two-choose-one selector;

[0123] The second input terminal of the second two-to-one selector is connected to a preset second voltage V H , the output terminal is connected to the non-inverting input terminal of the first comparator COMP1;

[0124] The output terminal of the first comparator COMP1 outputs the conduction time T ON .

[0125] Specifically, VI converters, such as Figure 3 As shown, it may include:

[0126] Current Source I SS , MOS tube M2, MOS tube M3, transistor Q1, transistor Q2 and resistor R6; wherein,

[0127] Current Source I SS The first end is connected to the source of the MOS tube M3, and the second end is connected to the base of the transistor Q1;

[0128] The source of the MOS tube M2 is connected to the source of the MOS tube M3, the gate is connected to the gate of the MOS tube M3, and the drain serves as the first output terminal of the VI converter;

[0129] The source of MOS tube M3 is connected to the power supply voltage V DD , the gate is connected to its own drain, and the drain is connected to the collector of transistor Q1;

[0130] The emitter of transistor Q1 is connected to the first end of resistor R6;

[0131] The collector of transistor Q2 is connected to the second end of resistor R6, the base serves as the second output end of VI converter, and the emitter is connected to the base of transistor Q1;

[0132] A second terminal of the resistor R6 is grounded.

[0133] Filter circuits, such as Figure 3 As shown, it may include:

[0134] Resistor R4, resistor R5, capacitor C2 and capacitor C3; wherein,

[0135] The first end of the resistor R4 serves as the input end of the filter circuit, and the second end is connected to the first end of the resistor R5;

[0136] A first end of the resistor R5 is connected to a first end of the capacitor C2, and a second end of the resistor R5 is connected to a first end of the capacitor C3;

[0137] The second end of the capacitor C2 serves as the grounding terminal of the filter circuit;

[0138] The first end of the capacitor C3 serves as the output end of the filter circuit, and the second end is connected to the second end of the capacitor C2.

[0139] The adaptive on-time module AOT is used to adjust the steady-state voltage V corresponding to the switch tube in the output module. SW The conduction time T corresponding to the conduction signal ON. In the corresponding conduction time T ON During the process, when the Sign signal output by the transient enhancement module indicates that the Buck converter jumps from heavy load to light load, the first two-choice selector selects the preset first voltage V L Replace V C1 , in order to shorten the on-time T ON When the Sign signal output by the transient enhancement module indicates that the Buck converter jumps from light load to heavy load, the second two-choose-one selector selects the preset second voltage V H Replace V C1 , to extend the on-time T ON .

[0140] As can be understood, the adaptive on-time module AOT uses a DC steady-state voltage V SW and contains the input voltage V IN The current charges the capacitor to generate the corresponding on-time T ON , which reduces the degree of switching frequency fluctuation caused by non-ideal factors and stabilizes the operating frequency of the Buck converter.

[0141] Specifically, V SW is the voltage between the switch tube and the inductor in the Buck converter. When the switch tube is turned on, V SW =V IN -I L ·R ON1 , when the rectifier is turned on, V SW =I L ·R ON2 Among them, R ON1 Represents the on-resistance of the switch tube, R ON2 Represents the on-resistance of the rectifier tube, I L Indicates the load current. Figure 3 It can be seen that V SW After being divided by resistors R2 and R3, the voltage V is obtained at the output end of the filter circuit through the filter circuit. C1 Voltage V C1 The expression is as follows:

[0142]

[0143] Wherein, R2 represents the resistance value of resistor R2, R3 represents the resistance value of resistor R3, and D actual Indicates the actual duty cycle of the Buck converter.

[0144] NG1 is the trigger signal corresponding to the switch tube. When NG1 is high, the MOS tube M1 is turned off, and the capacitor C1 starts to charge. The charging current I C1 for:

[0145]

[0146] Among them, I1 changes with V C2 The increase of V C2 The current source I SS MOS tube M2, MOS tube M3, transistor Q1, transistor Q2 and resistor R6 form a VI converter. When the width-to-length ratio of MOS tube M2 and MOS tube M3 is equal and the resistance value of resistor R1 is equal to that of resistor R6, that is, (W / L) M2 =(W / L) M3 When R1=R6, the charging current I C1 It can be expressed as:

[0147]

[0148] The first comparator COMP1 compares V C1 and V C2 The size of V C1 Greater than V C2 When the first comparator COMP1 outputs a high level, T ON Start timing. As C1 gradually increases, when V C1 Less than V C2 When the comparator outputs a low level, the switch is turned off, and T ON When the timing ends, NG1 becomes low level, and the on-time T generated by the adaptive on-time module AOT ON The expression is as follows:

[0149]

[0150] Wherein, R2 represents the resistance value of resistor R2, R3 represents the resistance value of resistor R3, C1 represents the capacitance value of capacitor C1, R1 represents the resistance value of resistor R1, D actual Indicates the actual duty cycle of the Buck converter.

[0151] It can be seen from the above formula that the constant on-time generated by this circuit is independent of the load current, input and output voltage, and the on-resistance of the switch tube and the rectifier tube, thereby reducing the change of the switching frequency.

[0152] Transient Enhancement Module

[0153] Transient enhancement modules such as Figure 4 As shown, it may include:

[0154] Resistor R7, capacitor C4, second comparator COMP2 and third comparator COMP3; wherein,

[0155] The first end of resistor R7 is connected to the output voltage V of the Buck converter. OUT, the second end is connected to the first end of the capacitor C4;

[0156] The second end of the capacitor C4 is grounded;

[0157] The non-inverting input terminal of the second comparator COMP2 is connected to the first end of the capacitor C4, the inverting input terminal is connected to the non-inverting input terminal of the third comparator COMP3, and the output terminal outputs the signal Sign1;

[0158] The inverting input terminal of the third comparator COMP3 is connected to the non-inverting input terminal of the second comparator COMP2, and the output terminal outputs a signal Sign2;

[0159] The signal Sign1 and the signal Sign2 constitute the Sign signal.

[0160] The transient enhancement module is used to output a Sign signal to the comparison signal selection module when the output voltage of the Buck converter surges or undershoots to a preset threshold value when the load of the Buck converter jumps.

[0161] Specifically, the circuit structure of the transient enhancement module is as follows: Figure 4 As shown, resistor R7 and capacitor C4 form a voltage regulator to stabilize the output voltage. When the load current suddenly changes, the output voltage V OUT Overshoot or undershoot, V OUT_S The signal is still in the steady-state value, so when the output voltage drops to the preset threshold, the comparator outputs the Sign signal, and the positive input terminal of the error amplifier EA is connected by V REF Switch to V REF_HL signal, speeding up the output speed of the error amplifier EA and improving the transient overshoot voltage of the Buck converter. Figure 4 It can be seen that the second-stage selector in the selector module may include a first sub-selector and a second sub-selector, wherein the control end of the first sub-selector is connected to the signal Sign1, and when the load current of the Buck converter suddenly changes from light load to heavy load, the preset second reference voltage V REF_H As the signal to be compared; the control end of the second sub-selector is connected to the signal Sign2, when the Buck converter changes from light load to heavy load, the preset first reference voltage V REF_L as the signal to be compared; during the rest of the time, the signal output by the first-level selector is selected as the signal to be compared.

[0162] Sleep detection module Sleep

[0163] Sleep detection module Sleep, such as Figure 5 As shown, it may include:

[0164] The first inverter, the MOS tube MP1, the MOS tube MP2, the MOS tube MP3, the MOS tube MP4, the MOS tube MN1, the MOS tube MN2, the MOS tube MN3, the MOS tube MN4, the current source I SS and capacitor C SS ;in,

[0165] The input end of the first inverter is connected to the switch tube drive signal V COMP , the output end is connected to the gate of the MOS tube MP1;

[0166] The source of MOS tube MP1 and the current source I SS The output end is connected to the drain of the MOS tube MN1;

[0167] The source of MOS tube MP2 is connected to the power supply voltage V DD , the gate is connected to the gate of the MOS tube MP3, and the drain is connected to the source of the MOS tube MP3;

[0168] The source of the MOS transistor MP3 is connected to the source of the MOS transistor MP4, the gate is connected to the drain of the MOS transistor MN1, and the drain is connected to the drain of the MOS transistor MN2;

[0169] The gate of the MOS tube MP4 is used as the output end of the sleep detection module Sleep, and the drain is connected to the source of the MOS tube MN3;

[0170] The source of MOS tube MN1 and capacitor C SS The second end is connected to the gate of the MOS tube MP1, the drain is connected to the capacitor C SS A first end is connected;

[0171] The source of MOS tube MN2 is connected to the drain of MOS tube MN3, and the gate is connected to the capacitor C SS The first end of the transistor is connected to the drain electrode of the MOS tube MP4;

[0172] The source of MOS tube MN3 is grounded, and the gate is connected to capacitor C SS The first end of the MOS tube MN4 is connected to the drain of the MOS tube MN4;

[0173] The gate of the MOS tube MN4 is connected to the gate of the MOS tube MP4, and the drain is connected to the source of the MOS tube MP2;

[0174] Current Source I SS The input end is connected to the source of MOS tube MP2;

[0175] Capacitor C SS The second end is connected to the source of the MOS tube MN3.

[0176] The sleep detection module Sleep is used to drive the switch tube signal V COMP A detection is performed to determine whether the switch tube driving signal meets the preset conditions. If so, a sleep signal is output to control the Buck converter to enter the sleep state.

[0177] Specifically, the sleep detection module is as follows: Figure 5 As shown, V COMP The signal is the switch tube drive signal output by the PWM comparator. When the Buck converter is under extremely light load, the switch tube has a constant on-time, the inductor is charged, and the rectifier tube is turned off after the current passes zero. The load discharges slowly, and V COMP The longer the time at high level is, the COMP When high, MP1 is turned on, I SS Give C SS Charging, when V COMP When the high level lasts longer than the set time, C SS The voltage continues to increase and exceeds MN 2～4 and MP 2～4 When the positive voltage of the hysteresis comparator is reached, a sleep signal is output to shut down unnecessary modules to reduce power consumption in extremely light load states.

[0178] Output Module

[0179] Output module, used to drive the switch tube signal V COMP Control the conduction of its own switch tube, according to the conduction time T ON A rectifier tube driving signal is generated to control the conduction of its own rectifier tube to generate a periodic output voltage; an adaptive dead time circuit in the output module prevents the rectifier tube and the switch tube from being turned on at the same time.

[0180] The output module is composed of a bootstrap circuit Bootstrap, a logic circuit LOGIC, an adaptive dead time circuit DEAD TIME and a driving circuit DRIVER. Among them, the bootstrap circuit Bootstrap can be used to output a high voltage to the switch tube in the initial stage. The logic circuit LOGIC can be used to output a corresponding logic control signal according to the signal received by itself to control the working state of the switch tube or the rectifier tube. The adaptive dead time circuit DEAD TIME can add a dead time in which both tubes are not turned on according to different load currents to prevent losses caused by simultaneous conduction. The driving circuit DRIVER can be used to control the corresponding switch tube or rectifier tube according to the output results of the logic control signal and the adaptive dead time circuit DEAD TIME.

[0181] It can be understood that the fast transient response Buck converter proposed in the embodiment of the present invention, such as Figure 2 As shown, it may also include:

[0182] Zero current shutdown circuit ZCD, overcurrent protection circuit OCP, overtemperature protection circuit OTP, overvoltage protection circuit OVP, minimum opening time circuit Mininum Opening time, minimum shutdown time circuit Mininum Shutdowntime and mode selector Mode Select; wherein,

[0183] The zero current shutdown circuit ZCD can be used to shut down the rectifier tube located below when the inductor current passes through zero, to prevent reverse current from increasing system power consumption. When the Buck converter needs to transition from CCM mode to DCM mode, the fixed mode remains unchanged. Among them, the working state of CCM (Continuous Conduction Mode) is: within a switching cycle, the inductor current will never reach 0, and the inductor will never be "reset", which means that the inductor flux will never return to 0 during the switching cycle, and when the power tube is closed, there is still current flowing in the coil. The working state of DCM (Discontinuous Conduction Mode) is: within the switching cycle, the inductor current will always reach 0, which means that the inductor is properly "reset", that is, when the power switch is closed, the inductor current is zero.

[0184] The overcurrent protection circuit OCP can be used to prevent excessive current in the Buck converter and damage the circuit.

[0185] The over-temperature protection circuit OTP can be used to prevent the temperature in the Buck converter from being too high and damaging the circuit.

[0186] The overvoltage protection circuit OVP can be used to prevent the voltage in the Buck converter from being too high and damaging the circuit.

[0187] The minimum opening time circuit Mininum Opening time and the minimum shut-down time circuit MininumShutdown time can be used to ensure the shortest time that the switch tube is fixedly turned on in each switching cycle and the shortest time that the switch tube is fixedly turned off in each switching cycle, respectively, to ensure the stable operation of the Buck converter.

[0188] The mode selector Mode Select can be used to select the operating mode of the Buck converter.

[0189] The working principle of the fast transient response Buck converter proposed in the embodiment of the present invention is as follows: at the beginning, the voltage V output by the soft start circuit is selected. SS As the input voltage of the non-inverting input terminal of the error amplifier EA, when the EN enable terminal is valid, V REF The output voltage is established, and a feedback signal V is output through the resistor divider network.FB . V FB With V REF It is sent to the error amplifier EA for comparison and outputs the error amplified signal V EA . V EA and V F The PWM comparator performs comparison. F Drop to V EA When the PWM comparator flips, the upper switch tube turns on, the lower rectifier tube turns off, the inductor current and output voltage rise, and the adaptive on-time module AOT starts timing. The on-time is controlled and adjusted according to the input and output voltages, so that the switching frequency of the Buck converter is almost stable when working in CCM mode. After the timing ends, the switch tube turns off, the rectifier tube turns on, the inductor current and output voltage decrease, and a new cycle begins.

[0190] A simulation experiment is performed on the fast transient response Buck converter proposed in the embodiment of the present invention to verify the beneficial effects of the fast transient response Buck converter.

[0191] The embodiment of the present invention can be selected to perform overall simulation of the Buck converter based on TSMC 180nm BCD process after completing the circuit design. The overall simulation diagram of the fast transient response Buck converter is as follows: Figure 6 As shown, it can be seen that the input voltage of the Buck converter is 3.3V and the output voltage is 0.9V. When the load current is 1.5A, the Buck converter works in CCM mode, the output voltage ripple is 1.15mV, and the switching frequency is 4MHz; when the load current is 10mA, the Buck converter automatically changes frequency and works in DCM mode, the output voltage ripple is 4.3mV, the switching frequency is 104.4KHz, the output voltage ripple and the inductor current ripple increase, and the switching period becomes longer.

[0192] The waveform diagram of the key signals when the Buck converter is in steady state, such as Figure 7 As shown, it can be seen that V C1 The signal is V SW When the trigger signal (NG1) corresponding to the switch tube is high, V C2 The voltage gradually increases. When V C2 Greater than V C1 When T ON The output is high level, and the timing ends. Under the control of the adaptive on-time module AOT, the switch tube is turned off after the adaptive on-time. After the switch tube is turned off, the rectifier tube is turned on again after the dead time, and the Buck converter enters a new switching cycle.

[0193] In order to verify the frequency stability of the adaptive on-time circuit of the embodiment of the present invention, the switching period is compared under different load currents. Figure 8 As shown, it can be seen that when the load current is 1A, the Buck converter switching period is 500.6ns; when the load current is 3A, the Buck converter switching period is 496.6ns, and the period change rate is only 0.8%. It can be seen that the adaptive on-time circuit has obvious effect and the switching frequency is stable.

[0194] The comparison diagram of the output voltage and inductor current waveforms of the Buck converter with and without transient enhancement module when the load current jumps from heavy load to light load is shown in the figure below. Fig. 9 As shown in the figure, it can be seen that when the load current changes from 3A to 10mA, the change speed is 1.5A / μs. Without the transient enhancement circuit, the output voltage overshoots 43.6mV. After adding the transient enhancement circuit, the output voltage overshoot becomes 18.5mV, which is an increase of 58%. The effect is significant. L It can be seen from the waveform that when the output voltage surges, the adaptive on-time becomes longer and the load current rises faster.

[0195] The comparison diagram of the output voltage and inductor current waveforms of the Buck converter with and without the transient enhancement module when the load current jumps from light load to heavy load is shown in the figure below. Fig.10 As shown in the figure, it can be seen that when the load current changes from 10m A to 3A, the change speed is 1.5A / μs. Without the transient enhancement circuit, the output voltage undershoots 43.6mV. After adding the transient enhancement circuit, the output voltage undershoot becomes 20.3mV, which is an increase of 53%. The effect is significant. L It can be seen from the waveform that when the output voltage surges, the adaptive on-time becomes shorter and the load current drops faster.

[0196] Buck converter sleep module detection waveform, such as Fig.11 As shown, it can be seen that when the load is small, V COMP At high level for a long time, by detecting V COMP The time when the signal is at a high level determines whether the Buck converter enters the sleep state. When the Sleep signal is at a low level, the Buck converter enters the sleep mode.

[0197] In summary, it can be seen that the embodiment of the present invention provides a Buck converter with fast transient response, stable switching frequency, and extremely light load sleep, wherein the transient enhancement module improves the load overshoot by 58%, and the adaptive on-time module AOT changes the switching frequency by only 0.8% under different load currents. The sleep detection module detects whether the Buck converter is in an extremely light load state, thereby improving system efficiency.

[0198] The fast transient response Buck converter proposed in the present invention combines the advantages of current mode control and AOT control. By using the output voltage of the Buck converter as the negative feedback voltage and adding an error amplifier in the negative feedback control loop, the accuracy of the output voltage is improved, the current loop is stabilized, and the series resistance R of the output capacitor is reduced. ESR No specific restrictions; the transient enhancement module is used to judge the output voltage to ensure that when the load current changes suddenly, the output voltage can be quickly stabilized to reduce overshoot and undershoot, thereby improving the overall stability and reliability; the sleep detection module Sleep is used to detect the switch tube drive signal V COMP Detection is performed to control the Buck converter to enter a sleep state, thereby reducing power consumption and improving efficiency.

[0199] It should be noted that in the description of the present invention, it should be understood that 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 the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0200] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A fast transient response Buck converter based on AOT control, characterized in that: include: Comparison signal selection module, error amplifier EA, PWM comparator, adaptive on-time module AOT, output module, transient enhancement module and sleep detection module Sleep; Among them, The comparison signal selection module is used to select a signal according to the reference voltage V under the control of the Sign signal output by the transient enhancement module. REF and soft-start voltage V SS Output the signal to be compared; The error amplifier EA is used to convert the feedback signal V corresponding to the output voltage of the Buck converter FB Compare with the signal to be compared, and output the error amplified signal V EA ; The PWM comparator is used to amplify the error signal V EA The ripple voltage V corresponding to the inductor in the Buck converter F Compare and output the switch tube drive signal V COMP ; The adaptive on-time module AOT is used to adjust the steady-state voltage V corresponding to the switch tube in the output module. SW The conduction time T corresponding to the conduction signal ON ; The output module is used to drive the switch tube according to the signal V COMP Control the conduction of its own switch tube, according to the conduction time T ON Generate a rectifier tube drive signal to control the conduction of its own rectifier tube to generate a periodic output voltage; the output module uses an internal adaptive dead time circuit to prevent the rectifier tube and the switch tube from being turned on at the same time; The transient enhancement module is used to output a Sign signal to the comparison signal selection module when the output voltage of the Buck converter overshoots or undershoots to a preset threshold value when the load of the Buck converter jumps; The sleep detection module Sleep is used to drive the switch tube signal V COMP Detection is performed to determine the switch tube drive signal V COMP Whether the preset conditions are met, if so, a sleep signal is output to control the Buck converter to enter a sleep state.

2. A fast transient response Buck converter based on AOT control according to claim 1, characterized in that: The comparison signal selection module comprises: Reference circuit BG, soft start circuit Soft Start and selector module.

3. A fast transient response Buck converter based on AOT control according to claim 2, characterized in that: The comparison signal selection module, under the control of the Sign signal output by the transient enhancement module, generates a comparison signal according to the reference voltage V REF and soft-start voltage V SS Output the signal to be compared, including: The reference circuit BG generates a reference voltage V REF ; The soft start circuit Soft Start generates a soft start voltage V SS ; The selector module is controlled by the Sign signal output by the transient enhancement module according to the reference voltage V REF and the soft-start voltage V SS Output the signal to be compared.

4. The fast transient response Buck converter based on AOT control according to claim 1, characterized in that: The adaptive on-time module AOT comprises: VI converter, inverter, MOS tube M1, capacitor C1, resistor R1, resistor R2, resistor R3, filter circuit, first two-choice selector, second two-choice selector and first comparator COMP1; wherein, The input terminal of the VI converter is connected to the power supply voltage V DD , a first output terminal is connected to the inverting input terminal of the first comparator COMP1, and a second output terminal is connected to the first terminal of the capacitor C1; The input end of the inverter is connected to the trigger signal NG1 corresponding to the switch tube, and the output end is connected to the gate of the MOS tube M1; The source of the MOS tube M1 is grounded, and the drain is connected to the first end of the capacitor C1; The first end of the capacitor C1 is connected to the inverting input end of the first comparator COMP1, and the second end is connected to the source of the MOS transistor M1; The first end of the resistor R1 is connected to the steady-state voltage V corresponding to the switch tube SW , the second end is connected to the first end of the capacitor C1; The first end of the resistor R2 is connected to the first end of the resistor R1, and the second end is connected to the first end of the resistor R3; The first end of the resistor R3 is connected to the input end of the filter circuit, and the second end is grounded; The output end of the filter circuit is connected to the first input end of the second two-to-one selector, and the ground end is grounded; The first input terminal of the first two-to-one selector is connected to a preset first voltage V L , the second input end is connected to the first input end of the second two-selector, the control end is connected to the Sign signal output by the transient enhancement module, and the output end is connected to the output end of the second two-selector; The second input terminal of the second two-to-one selector is connected to a preset second voltage V H , the output end is connected to the non-inverting input end of the first comparator COMP1; The output terminal of the first comparator COMP1 outputs the conduction time T ON .

5. A fast transient response Buck converter based on AOT control according to claim 4, characterized in that: The VI converter comprises: Current Source I SS , MOS tube M2, MOS tube M3, transistor Q1, transistor Q2 and resistor R6; wherein, Current Source I SS The first end is connected to the source of the MOS tube M3, and the second end is connected to the base of the transistor Q1; The source of the MOS tube M2 is connected to the source of the MOS tube M3, the gate is connected to the gate of the MOS tube M3, and the drain serves as the first output end of the VI converter; The source of the MOS tube M3 is connected to the power supply voltage V DD , the gate is connected to its own drain, and the drain is connected to the collector of the transistor Q1; The emitter of the transistor Q1 is connected to the first end of the resistor R6; The collector of the transistor Q2 is connected to the second end of the resistor R6, the base serves as the second output end of the VI converter, and the emitter is connected to the base of the transistor Q1; A second end of the resistor R6 is grounded.

6. The fast transient response Buck converter based on AOT control according to claim 4, characterized in that: The filtering circuit comprises: Resistor R4, resistor R5, capacitor C2 and capacitor C3; wherein, The first end of the resistor R4 serves as the input end of the filter circuit, and the second end is connected to the first end of the resistor R5; The first end of the resistor R5 is connected to the first end of the capacitor C2, and the second end is connected to the first end of the capacitor C3; The second end of the capacitor C2 serves as the grounding end of the filter circuit; The first end of the capacitor C3 serves as the output end of the filter circuit, and the second end is connected to the second end of the capacitor C2.

7. The fast transient response Buck converter based on AOT control according to claim 4, characterized in that: The on-time T generated by the adaptive on-time module AOT ON The expression is as follows: Wherein, R2 represents the resistance value of resistor R2, R3 represents the resistance value of resistor R3, C1 represents the capacitance value of capacitor C1, R1 represents the resistance value of resistor R1, D actual Indicates the actual duty cycle of the Buck converter.

8. The fast transient response Buck converter based on AOT control according to claim 1, characterized in that: The transient enhancement module comprises: Resistor R7, capacitor C4, second comparator COMP2 and third comparator COMP3; wherein, The first end of the resistor R7 is connected to the output voltage V of the Buck converter. OUT , the second end is connected to the first end of the capacitor C4; The second end of the capacitor C4 is grounded; The non-inverting input terminal of the second comparator COMP2 is connected to the first end of the capacitor C4, the inverting input terminal is connected to the non-inverting input terminal of the third comparator COMP3, and the output terminal outputs the signal Sign1; The inverting input terminal of the third comparator COMP3 is connected to the non-inverting input terminal of the second comparator COMP2, and the output terminal outputs a signal Sign2; The signal Sign1 and the signal Sign2 constitute a Sign signal.

9. The fast transient response Buck converter based on AOT control according to claim 1, characterized in that: The sleep detection module Sleep comprises: The first inverter, the MOS tube MP1, the MOS tube MP2, the MOS tube MP3, the MOS tube MP4, the MOS tube MN1, the MOS tube MN2, the MOS tube MN3, the MOS tube MN4, the current source I SS1 and capacitor C SS ;in, The input end of the first inverter is connected to the switch tube drive signal V COMP , the output end is connected to the gate of the MOS tube MP1; The source of the MOS tube MP1 is connected to the current source I SS1 The output end of the transistor is connected to the drain of the MOS transistor MN1; The source of the MOS tube MP2 is connected to the power supply voltage V DD , a gate electrode is connected to the gate electrode of the MOS tube MP3, and a drain electrode is connected to the source electrode of the MOS tube MP3; The source of the MOS transistor MP3 is connected to the source of the MOS transistor MP4, the gate is connected to the drain of the MOS transistor MN1, and the drain is connected to the drain of the MOS transistor MN2; The gate of the MOS transistor MP4 serves as the output end of the sleep detection module Sleep, and the drain is connected to the source of the MOS transistor MN3; The source of the MOS tube MN1 and the capacitor C SS The second end is connected to the gate of the MOS tube MP1, the drain is connected to the capacitor C SS A first end is connected; The source of the MOS transistor MN2 is connected to the drain of the MOS transistor MN3, and the gate is connected to the capacitor C SS The first end of the MOS tube MP4 is connected to the drain electrode thereof, and the drain electrode is connected to the gate electrode of the MOS tube MP4; The source of the MOS tube MN3 is grounded, and the gate is connected to the capacitor C SS The first end of the MOS tube MN4 is connected to the drain of the MOS tube MN4; The gate of the MOS transistor MN4 is connected to the gate of the MOS transistor MP4, and the drain is connected to the source of the MOS transistor MP2; The current source I SS1 The input end is connected to the source of the MOS tube MP2; The capacitor C SS The second end is connected to the source of the MOS tube MN3.

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