Switching power supply circuit and power supply chip

Abstract

The invention discloses a switching power supply circuit and a power supply chip, and relates to the technical field of switching power supply chips, the switching power supply circuit is provided with a continuous conduction mode and an intermittent conduction mode, the switching power supply circuit comprises a switching circuit, the input end of the switching circuit is used for accessing an external power supply, and the output end of the switching circuit is used for accessing an external load; the switch control driving circuit is electrically connected with the controlled end of the switch circuit, the switch control driving circuit is used for controlling the switch circuit to work, and in the continuous conduction mode, the first feedback loop starts to work, generates a charging signal according to the first voltage signal, and outputs the charging signal to the switch control driving circuit to control the switch circuit to work; and in the interrupted conduction mode, the second feedback loop is started to work, generates a charging signal according to the second voltage signal, and outputs the charging signal to the switch control driving circuit to control the switch circuit to work, so that the problem of excessive working loops of the adaptive switching power supply chip detection loop can be reduced, and the power consumption of the chip is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supply chips, and in particular to a switching power supply circuit and a power supply chip. Background Art

[0002] With the continuous development of the electronics, communications, and medical industries, the requirements for the performance of switching power supplies are also increasing. As an important component of power management chips, switching power supplies have the advantages of high efficiency, high voltage step-down ratio, and low output ripple, and are often used in DC-DC step-down power supply chips. In small-volume, low-voltage battery-powered consumer electronic products such as medical monitoring, smart wearable devices, and high-speed, small-volume storage devices, it is necessary to maintain low power consumption and high endurance for a long time. Therefore, low-power DC-DC power supply chips have advantages in reducing the energy consumption of electronic devices and extending battery life. For low-power Wi-Fi modules, central processing units (CPUs), and digital-to-analog converters that require low-voltage power supply, the voltage power supply also requires DC-DC step-down power supply chips for step-down buffering to supply power. How to design a DC-DC step-down power supply chip with lower power consumption has always been a key challenge in this field. Selecting constant on-time control (COT) and pulse width modulation (PFM) can reduce switching losses and maintain high efficiency under light load conditions. However, under heavy and medium load conditions, the switching power supply operates in continuous conduction mode CCM (Continuous Conduction Mode). The characteristic of this mode is that within a switching cycle, the inductor current is continuous, and the inductor current can drop to 0 but will not remain at 0. Since the on-time is constant, the switching power supply frequency will be affected by changes in the input voltage and output voltage, resulting in changes in the duty cycle and the inability to achieve constant switching frequency. Adaptive on-time control (AOT) can dynamically adjust the on-time according to the input voltage and output voltage, thereby maintaining a constant switching frequency of the power chip under CCM. In the discontinuous conduction mode DCM (Discontinuous Conduction Mode) with light load, this mode is characterized by a period in which the inductor current is always maintained at 0 within a switching cycle. This solution can dynamically reduce the frequency, showing a PFM characteristic, thereby reducing switching losses and maintaining high efficiency.

[0003] Although adaptive on-time control can improve efficiency at light load, there are usually high power consumption feedback loops and comparators. In light load mode, if the loop is kept running uninterrupted, the light load efficiency of the power chip will be reduced. Minimizing the part of the loop working as much as possible in DCM will effectively improve the light load efficiency of the power chip.

[0004] In traditional power management chips, if the chip uses a second feedback loop and operates near zero inductor current in DCM, there is a certain delay in the response of the second feedback loop, and subharmonic oscillation will occur in the output voltage VOUT, resulting in an unstable output voltage and failing to achieve the desired effect. Summary of the invention

[0005] The main purpose of the present invention is to provide a switching power supply circuit and a power supply chip, aiming to solve the problem of excessive power consumption of the switching power supply chip in light load mode due to too many detection loop working loops.

[0006] To achieve the above object, the present invention provides a switching power supply circuit, wherein the switching power supply circuit has a continuous conduction mode and a discontinuous conduction mode, and the circuit comprises:

[0007] A switch circuit, wherein an input end of the switch circuit is used to connect to an external power supply, and an output end of the switch circuit is used to connect to an external load;

[0008] A switch control driving circuit is electrically connected to a controlled end of the switch circuit, and the switch control driving circuit is used to control the operation of the switch circuit;

[0009] A first feedback loop, wherein an input end of the first feedback loop is electrically connected to an output end of the switch circuit, and an output end of the first feedback loop is electrically connected to a signal feedback end of the switch control drive circuit;

[0010] a second feedback loop, wherein an input end of the second feedback loop is electrically connected to an output end of the switch circuit, and an output end of the second feedback loop is electrically connected to a signal feedback end of the switch control drive circuit;

[0011] In the continuous conduction mode, the first feedback loop starts to work, and the first feedback loop processes the first voltage signal output by the switch circuit to generate a charging signal, and outputs the charging signal to the switch control drive circuit, so that the switch control drive circuit controls the switch circuit to work according to the charging signal;

[0012] In the intermittent conduction mode, the second feedback loop starts working, and the second feedback loop processes the second voltage signal output by the switch circuit to generate a charging signal, and outputs it to the switch control drive circuit, so that the switch control drive circuit controls the operation of the switch circuit according to the charging signal.

[0013] In one embodiment, the first feedback loop further includes

[0014] a first voltage amplifier, wherein a positive input terminal of the first voltage amplifier is connected to a reference power supply electrical connection terminal, and a negative input terminal of the first voltage amplifier is electrically connected to an output terminal of the switch circuit, and is used for amplifying and outputting a first voltage signal and a reference voltage signal received as feedback from an external load;

[0015] A first voltage comparator, wherein a negative input terminal of the first voltage comparator is electrically connected to a first output terminal of the first voltage amplifier, and a positive input terminal of the first voltage comparator is electrically connected to a second output terminal of the first voltage amplifier, and is configured to output a first voltage amplification signal when a first voltage signal of an external load after receiving the amplification is less than a reference voltage signal after the amplification;

[0016] A current comparator, wherein the negative input terminal of the current comparator is connected to the inductor current sampling terminal, and the positive input terminal of the current comparator is electrically connected to the output terminal of the first voltage comparator, and is used to calculate according to the sampling current value sent by the inductor current sampling terminal and the first voltage amplification signal received, so as to output the charging signal to the switch control drive circuit when a preset charging threshold is reached.

[0017] In one embodiment, the second feedback loop comprises:

[0018] a second voltage amplifier, wherein the positive input terminal of the second voltage amplifier is connected to the reference power supply connection terminal, and the negative input terminal of the first voltage amplifier is connected to the output terminal of the switch circuit, and is used to receive the second voltage signal of the external load and the reference voltage signal and then amplify and output them;

[0019] a second voltage comparator, wherein a negative input terminal of the second voltage comparator is electrically connected to a first output terminal of the second voltage amplifier, and a positive input terminal of the second voltage comparator is electrically connected to a second output terminal of the second voltage amplifier, and is configured to output a charging operation comparison signal when a second voltage signal of the external load after receiving the amplification is greater than a reference voltage signal;

[0020] A third voltage comparator, wherein the negative input terminal of the third voltage comparator is electrically connected to the output terminal of the second voltage comparator, and the positive input terminal of the third voltage comparator is connected to the slope compensation circuit connection terminal, and is used to compare the received charging operation comparison signal with the slope compensation voltage signal sent by the slope compensation circuit, so as to output the charging signal to the switch control drive circuit when the slope compensation voltage signal is reached.

[0021] In one embodiment, the switching power supply circuit further includes:

[0022] A slope compensation circuit is electrically connected to the positive input terminal of the third voltage comparator and is used to provide a slope compensation voltage signal for preventing secondary harmonic oscillation.

[0023] In one embodiment, the slope compensation circuit comprises:

[0024] A first PMOS tube, a second PMOS tube, a third PMOS tube, a first current mirror, a second current mirror, a first capacitor and a working power supply connection terminal, wherein;

[0025] The input end of the first current mirror and the input end of the second current mirror are electrically connected to the working power supply connection end respectively; the output end of the first current mirror is electrically connected to the source of the first PMOS tube, the first end of the first capacitor, the source of the second PMOS tube, the drain of the third PMOS tube and the positive input end of the third voltage comparator respectively; the output end of the second current mirror is electrically connected to the source of the third PMOS tube, the gate of the third PMOS tube is electrically connected to the output end of the first voltage inverter, the second end of the first capacitor, the gate of the first PMOS tube, the drain of the first PMOS tube and the drain of the second PMOS tube are grounded respectively, and the gate of the second PMOS tube is electrically connected to the output end of the second voltage inverter.

[0026] In one embodiment, the switch control driving circuit includes:

[0027] a multiplexer, wherein a first input end of the multiplexer is connected to an output end of the first feedback loop, and a second input end of the multiplexer is connected to an output end of the second feedback loop, and is used to output the charging signal received from the first feedback loop or the second feedback loop;

[0028] An RS controller, wherein a first input terminal of the RS controller is connected to an output terminal of the multiplexer, and is used for processing and generating a charging control signal and then outputting the charging control signal when receiving the charging signal;

[0029] A logic control and driver, wherein the input end of the logic control and driver is electrically connected to the output end of the RS controller, and the output end of the logic control and driver is electrically connected to the controlled end of the switch circuit, and is used to process the received charging control signal to generate a charging drive signal to drive the switch circuit to operate in a charging state.

[0030] In one embodiment, the switching power supply circuit further includes:

[0031] A discharge state conversion circuit, wherein the input end of the discharge state conversion circuit is electrically connected to the output end of the switch circuit, and the output end of the discharge state conversion circuit is electrically connected to the second input end of the RS controller, and is used to send a discharge signal to the RS controller, and the RS controller generates a discharge control signal and then outputs it, so as to control the logic control and driver to generate a discharge drive signal according to the discharge control signal, and drive the switch circuit to work in a discharge state.

[0032] In one embodiment, the switching power supply circuit further includes:

[0033] A sleep state conversion circuit, wherein the negative input terminal of the sleep state conversion circuit is connected to the inductor current sampling terminal, the positive input terminal of the sleep state conversion circuit is connected to the switch circuit, and the output terminal of the sleep state conversion circuit is electrically connected to the input terminal of the logic control and driver, and is used to generate a sleep control signal when it is detected that the inductor current is zero, so as to control the logic control and driver to generate a sleep drive signal according to the sleep control signal, so as to drive the switch circuit to work in the sleep state.

[0034] In one embodiment, the switch circuit comprises:

[0035] a first switch tube, wherein a source of the first switch tube is connected to an external power supply, a gate of the first switch tube is electrically connected to an output end of the logic control and driver, and a drain of the first switch tube is electrically connected to the external load;

[0036] A second switch tube, wherein the source of the second switch tube is electrically connected to the drain of the first switch tube and the external load respectively, the gate of the second switch tube is electrically connected to the output end of the logic control and driver, and the drain of the second switch tube is electrically connected to the positive input end of the sleep state conversion circuit, wherein;

[0037] When the logic control and driver outputs a charging drive signal, the first switch tube is controlled to be turned on and the second switch tube is controlled to be turned off; when the logic control and driver outputs a discharging drive signal, the first switch tube is controlled to be turned off and the second switch tube is controlled to be turned on; when the logic control and driver outputs a sleep drive signal, the first switch tube and the second switch tube are controlled to be turned off.

[0038] The present invention further provides a power chip, which includes the switching power circuit as described above.

[0039] The technical solution of the present invention adopts a switching power supply circuit, which has a continuous conduction mode and a discontinuous conduction mode. The circuit includes: a switching circuit, the input end of the switching circuit is used to connect to an external power supply, and the output end of the switching circuit is used to connect to an external load; a switch control drive circuit, which is electrically connected to the controlled end of the switching circuit, and the switch control drive circuit is used to control the operation of the switching circuit; a first feedback loop, the input end of the first feedback loop is electrically connected to the output end of the switching circuit, and the output end of the first feedback loop is electrically connected to the signal feedback end of the switch control drive circuit; a second feedback loop, the input end of the second feedback loop is electrically connected to the output end of the switching circuit The output end of the second feedback loop is electrically connected to the signal feedback end of the switch control driving circuit; in the continuous conduction mode, the first feedback loop starts working, the first feedback loop processes the first voltage signal output by the switch circuit to generate a charging signal, and outputs it to the switch control driving circuit, so that the switch control driving circuit controls the switch circuit to work according to the charging signal; in the intermittent conduction mode, the second feedback loop starts working, the second feedback loop processes the second voltage signal output by the switch circuit to generate a charging signal, and outputs it to the switch control driving circuit, so that the switch control driving circuit controls the switch circuit to work according to the charging signal. In this way, the switching power supply circuit can start the first feedback loop in the continuous conduction mode or start the second feedback loop in the intermittent conduction mode, so that the switching power supply circuit can reduce the problem of too many detection loop working loops of the adaptive switching power supply chip in the light load mode, and effectively reduce the chip power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0041] Figure 1 A system block diagram of an embodiment of a switching power supply circuit provided by the present invention;

[0042] Figure 2 A specific structural diagram of an embodiment of a switching power supply circuit provided by the present invention;

[0043] Figure 3 A schematic diagram of the structure of a slope compensation circuit in another embodiment of the switching power supply circuit provided by the present invention;

[0044] Figure 4A schematic diagram of changes in circuit-related signals during operation of the switching power supply circuit provided by the present invention in the intermittent conduction mode and the continuous conduction mode.

[0045] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0048] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0049] In the DC-DC step-down power supply chip with adaptive on-time modulation in the AOT control mode, this type of chip often greatly increases the power consumption of this type of power switch chip in order to keep the detection loop running uninterruptedly so that the chip can switch the working mode in time.

[0050] It is worth mentioning that in the AOT control mode, the circuit between the step-down power supply chip and the external load is often provided with an inductor and a capacitor to filter the voltage output to the external load, and the switching power supply chip of this scheme can operate in the continuous conduction mode when using heavy load and medium load. The characteristic of this mode is that the inductor is repeatedly converted in the charging-discharging state within a switching cycle. The inductor current in the switching power supply chip in the continuous conduction mode is continuous, and the inductor current can be reduced to 0, but it will not be maintained at 0 continuously. It can also switch to the discontinuous conduction mode under the light load state. The characteristic of this mode is that the inductor current in the switching power supply chip in the discontinuous conduction mode is repeatedly converted in the charging-discharging-sleep state within a switching cycle. There is always a section of the inductor current maintained at 0 in the switching power supply chip in the discontinuous conduction mode. It is also possible to stop the operation of certain components (i.e., the sleep state) by utilizing the state where the inductor current is maintained at 0, thereby reducing switching losses and maintaining high efficiency.

[0051] Please refer to Figures 1 to 3 The present invention provides a switching power supply circuit, wherein the switching power supply circuit has a continuous conduction mode and a discontinuous conduction mode, and the circuit comprises:

[0052] A switch circuit 1, wherein the input end of the switch circuit 1 is used to connect to an external power supply, and the output end of the switch circuit 1 is used to connect to an external load;

[0053] A switch control driving circuit 2, electrically connected to a controlled end of the switch circuit 1, and the switch control driving circuit 2 is used to control the operation of the switch circuit 1;

[0054] A first feedback loop 3, wherein an input end of the first feedback loop 3 is electrically connected to an output end of the switch circuit 1, and an output end of the first feedback loop 3 is electrically connected to a signal feedback end of the switch control drive circuit 2;

[0055] A second feedback loop 4, wherein an input end of the second feedback loop 4 is electrically connected to an output end of the switch circuit 1, and an output end of the second feedback loop 4 is electrically connected to a signal feedback end of the switch control drive circuit 2;

[0056] In the continuous conduction mode, the first feedback loop 3 starts to work, and the first feedback loop 3 processes the first voltage signal output by the switch circuit 1 to generate a charging signal, and outputs the charging signal to the switch control drive circuit 2, so that the switch control drive circuit 2 controls the switch circuit 1 to work according to the charging signal;

[0057] In the intermittent conduction mode, the second feedback loop 4 starts working, and the second feedback loop 4 processes the second voltage signal output by the switch circuit 1 to generate a charging signal, and outputs it to the switch control drive circuit 2, so that the switch control drive circuit 2 controls the switch circuit 1 to work according to the charging signal.

[0058] In this embodiment, the switch circuit 1 can be implemented by one or more transistors, the switch control drive circuit 2 can be implemented by PLC (Programmable Logic Controller), MCU (Microcontroller Unit), DSP (Digital Signal Process), FPGA (Field Programmable Gate Array), SOC (System OnChip), etc. The first feedback loop 3 and the second feedback loop 4 can be implemented by using an amplifier and a comparator in combination. The first voltage signal and the second voltage signal are both voltage values ​​within a certain range (for example, the voltage value V1 of the first voltage signal is set to be less than a preset threshold value of 600MV, and the voltage value V2 of the second voltage signal is set to be greater than or equal to the preset threshold value of 600MV). R&D personnel can set the voltage range values ​​of the first voltage signal and the second voltage signal according to product requirements. The first voltage signal only needs to be set to be less than the second voltage signal to ensure that the two are mutually exclusive, so no fixed value limitation is made here;

[0059] Specifically, when the switching power supply circuit operates in the continuous conduction mode, the output voltage of the external load is a first voltage signal, and the first feedback loop 3 processes the first voltage signal output by the switching circuit 1 to generate a charging signal, and outputs the charging signal to the switching control drive circuit 2, so that the switching control drive circuit 2 controls the switching circuit 1 to work according to the charging signal;

[0060] When the switching power supply circuit operates in the intermittent conduction mode, the output voltage of the external load is a second voltage signal, and the second feedback loop 4 processes the second voltage signal output by the switching circuit 1 to generate a charging signal, and outputs the charging signal to the switching control drive circuit 2, so that the switching control drive circuit 2 controls the switching circuit 1 to operate according to the charging signal, thereby enabling the switching power supply circuit to enter the charging state in the continuous conduction mode or the intermittent conduction mode;

[0061] It is worth mentioning that since the step-down power supply switch chip in the AOT control mode is often provided with a filter circuit composed of an inductor and a capacitor, when the external load connected to the switch circuit 1 is lightly loaded, the current in the line between the external load and the switch circuit 1 decreases, and the capacitor in the filter circuit is continuously charged, so that the voltage output by the switch circuit 1 to the external load increases, and the voltage output feedback to the first feedback loop 3 and the second feedback loop 4 also increases accordingly. When the feedback voltage rises from the first voltage signal to the second voltage signal, it switches to the second feedback loop 4 to start working, otherwise it switches to the first feedback loop 3 to start working, and by setting a corresponding logic circuit, when the voltage rises from the first voltage signal to the second voltage signal, the comparison components in the first feedback loop 3 are stopped from working, thereby reducing power consumption.

[0062] Furthermore, the first feedback loop 3 also includes:

[0063] a first voltage amplifier, wherein a positive input terminal of the first voltage amplifier is connected to a reference power supply electrical connection terminal, and a negative input terminal of the first voltage amplifier is electrically connected to an output terminal of the switch circuit 1, and is used for amplifying and outputting a first voltage signal and a reference voltage signal received as feedback from an external load;

[0064] a first voltage comparator COMP1, wherein a negative input terminal of the first voltage comparator COMP1 is electrically connected to a first output terminal of the first voltage amplifier, and a positive input terminal of the first voltage comparator COMP1 is electrically connected to a second output terminal of the first voltage amplifier, and is configured to output a first voltage amplification signal when a first voltage signal of an external load after receiving the amplification is less than a reference voltage signal after the amplification;

[0065] A current comparator ICMP, wherein the negative input terminal of the current comparator ICMP is connected to the inductor current sampling terminal, and the positive input terminal of the current comparator ICMP is electrically connected to the output terminal of the first voltage comparator COMP1, and is used to calculate according to the sampled current value sent by the inductor current sampling terminal and the first voltage amplified signal received, so as to output the charging signal to the switch control drive circuit 2 when a preset charging threshold is reached.

[0066] In this embodiment, the first voltage amplifier can be implemented by an error amplifier, the first voltage comparator COMP1 can be implemented by an error comparator, the reference power supply can be implemented by a reference circuit or an external power supply, and the real-time monitoring of the inductor current in the circuit can be implemented by a current sensor or an RI module, and the current value of the monitored inductor current is output to the inductor current sampling terminal, wherein, in the continuous conduction mode, the current comparator not only performs feedback adjustment according to the monitored inductor current change, but also performs feedback adjustment according to the monitored first voltage signal change, so as to control the output state of the current comparator ICMP;

[0067] Specifically, when the first voltage amplifier receives the first voltage signal and the reference voltage signal fed back by the external load for amplification, the amplified first voltage signal is output to the negative electrode of the first voltage comparator COMP1, and the amplified reference voltage signal is output to the positive electrode of the first voltage comparator COMP1. When the amplified first voltage signal of the external load received by the first voltage comparator COMP1 is less than the amplified reference voltage signal, the first voltage amplified signal is output to the positive input terminal of the current comparator. The first voltage amplified signal is used as a comparison reference parameter of the current comparator ICMP, and is used to perform corresponding weighted calculation processing with the sampled current value and the working voltage value received by the power supply end (not shown in the figure) of the current comparator, and then add them to generate a comparison value (for example, the first voltage amplified signal+current weight*sampled current). The sample current value + working voltage weight * working voltage value is equal to the comparison value OUTM, that is, PIBI1*12k+0.6*SW+0.4*INTVCC=OUTM) is compared with the preset charging threshold. The preset charging threshold (for example, the working voltage weight * working voltage value + constant threshold is equal to the preset charging threshold OUTP, that is, 0.4*INTVCC+PIBI0*12k=OUTP) can be generated by the current comparator through the external resistor voltage division working voltage obtained by weighted calculation and the working voltage value. When it drops to the preset charging threshold, a charging signal is output to the switch control drive circuit 2, so that the switch control drive circuit 2 controls the switch circuit 1 to work according to the charging signal, and controls the switch circuit 1 to realize the conversion from the discharge state of the continuous conduction mode to the charging state.

[0068] It is worth mentioning that in the discharge state of the continuous conduction mode, the inductor current and the load voltage will continue to decrease. The first voltage amplification signal is amplified by the load voltage when it is the first voltage signal, and the comparison value generated thereby will also continue to decrease.

[0069] In one embodiment, the second feedback loop 4 comprises:

[0070] a second voltage amplifier, wherein the positive input terminal of the second voltage amplifier is connected to the reference power supply connection terminal, and the negative input terminal of the first voltage amplifier is connected to the output terminal of the switch circuit 1, and is used to receive the second voltage signal of the external load and the reference voltage signal, and output them after amplification;

[0071] a second voltage comparator COMP2, wherein a negative input terminal of the second voltage comparator COMP2 is electrically connected to a first output terminal of the second voltage amplifier, and a positive input terminal of the second voltage comparator COMP2 is electrically connected to a second output terminal of the second voltage amplifier, and is configured to output a charging operation comparison signal when a second voltage signal of the external load after receiving the amplification is greater than a reference voltage signal;

[0072] A third voltage comparator COMP4, wherein the negative input terminal of the third voltage comparator COMP4 is electrically connected to the output terminal of the second voltage comparator COMP2, and the positive input terminal of the third voltage comparator COMP4 is connected to the connection terminal of the slope compensation circuit 7, and is used to compare the received charging operation comparison signal with the slope compensation voltage signal sent by the slope compensation circuit 7, so as to output the charging signal to the switch control drive circuit 2 when the slope compensation voltage signal is reached.

[0073] In this embodiment, the second voltage amplifier can be implemented by an error amplifier, the second voltage comparator COMP2 and the third voltage comparator COMP4 can be implemented by error comparators, and the reference power supply can be implemented by a reference circuit or an external power supply. When the second voltage amplifier receives the second voltage signal and the reference voltage signal fed back by the external load for amplification, the amplified second voltage signal is output to the negative electrode of the second voltage comparator COMP2, and the amplified reference voltage signal is output to the positive electrode of the second voltage comparator COMP2, and the amplified first voltage signal of the external load is received through the first voltage comparator COMP1. After the signal is compared with the amplified reference voltage signal, a charging operation comparison signal is output to the negative input terminal of the third voltage comparator COMP4. The slope compensation voltage signal received by the positive input terminal of the third voltage comparator COMP4 is used as a non-constant voltage threshold of the third voltage comparator COMP4, so that when the charging operation comparison signal rises and reaches the voltage threshold, the charging signal is output to the switch control driving circuit 2, so that the switch control driving circuit 2 controls the switch circuit 1 to work according to the charging signal, and controls the switch circuit 1 to switch from the sleep working state to the charging working state in the intermittent conduction mode;

[0074] The charging operation comparison signal is specifically an error amplified voltage value, the slope compensation voltage signal is also a voltage value, and the first voltage amplifier and the second voltage amplifier can be set to the same component (for example Figure 2 The charging operation comparison signal is implemented by a voltage amplifier AMP1 with a dual-phase input and a dual-phase output or two voltage amplifiers that are independently set. Since the charging operation comparison signal has a certain time delay in the second feedback loop 4, there will be a certain phase delay. If there is no phase difference, the voltage output to the external load in the sleep stage in the intermittent conduction mode drops rapidly, and the corresponding charging operation comparison signal should rise rapidly. At this time, the third voltage comparator COMP4 only needs to compare the charging operation comparison signal with the slope compensation voltage signal. When the charging operation comparison signal rises to the slope compensation voltage signal, the output of the third voltage comparator COMP4 is flipped, and then it enters the charging stage.

[0075] In one embodiment, the switching power supply circuit further includes:

[0076] The slope compensation circuit 7 is electrically connected to the positive input terminal of the third voltage comparator COMP4 and is used to provide a slope compensation voltage signal for preventing secondary harmonic oscillation.

[0077] In this embodiment, since there is a phase difference between the voltage signal output to the load and the output signal of the second voltage comparator COMP2, during the sleep phase in the intermittent conduction mode, the charging operation comparison signal may have a valley value in this phase, that is, the charging operation comparison signal may first drop and then rise in this phase. Since the sleep time of the switching power supply circuit is short, if a constant comparison threshold provided by a reference circuit is used, the charging operation comparison signal will reach the comparison threshold when it drops, rather than rising to reach the comparison threshold, which will cause the third voltage comparator COMP4 to flip in advance and enter the charging phase of the next cycle, thereby causing subharmonic oscillation, so the slope compensation circuit 7 is introduced instead of using the reference circuit to provide a constant comparison threshold.

[0078] Furthermore, the slope compensation circuit 7 comprises:

[0079] A first PMOS transistor MP1, a second PMOS transistor MP2, a third PMOS transistor MP3, a first current mirror I1, a second current mirror I2, a first capacitor C1 and a working power supply connection terminal, wherein;

[0080] The input end of the first current mirror I1 and the input end of the second current mirror I2 are electrically connected to the working power supply connection end respectively; the output end of the first current mirror I1 is electrically connected to the source of the first PMOS tube MP1, the first end of the first capacitor C1, the source of the second PMOS tube MP2, the drain of the third PMOS tube MP3 and the positive input end of the third voltage comparator respectively; the output end of the second current mirror I2 is electrically connected to the source of the third PMOS tube MP3; the gate of the third PMOS tube MP3 is electrically connected to the output end of the first voltage inverter; the second end of the first capacitor C1, the gate of the first PMOS tube MP1, the drain of the first PMOS tube MP1 and the drain of the second PMOS tube MP2 are grounded respectively; and the gate of the second PMOS tube MP2 is electrically connected to the output end of the second voltage inverter.

[0081] In this embodiment, the working power supply connection terminal can be realized by providing a reference power supply by a reference circuit. The input end of the first voltage inverter is connected to the inductor in the switching power supply circuit, and is used to invert the voltage signal of the inductor, and outputs it to the gate of the third PMOS tube MP3 through the output end of the first voltage inverter (not shown in the figure). This is used as a switch to periodically control the charging and discharging of the first capacitor C1, thereby generating a triangular wave signal to provide a slope compensation voltage. The input end of the second voltage inverter (not shown in the figure) is connected to a certain switch tube in the switching circuit 1 (specifically Figure 2 The second switch tube MN in the circuit can be obtained by inverting the gate signal in the second switch tube MN → performing a logical AND operation with the gate signal in the first switch tube MP → inverting the gate signal. Figure 3 The SW2 signal in the circuit is used to make it low level when in the off state, so that the first capacitor C1 discharges faster, and the slope of the slope compensation voltage is larger in this stage. The first current mirror I1 and the second current mirror I2 are both used as bias current sources. The first current mirror I1 is used to charge the first capacitor C1, so that the first PMOS tube MP1 connected to the gate and the drain is in a critical conduction state.

[0082] Specifically, when the switching power supply circuit is in a charging state, the signal output by the first voltage inverter is low, the third PMOS tube MP3 is turned on, the signal output by the second voltage inverter is high, and the second PMOS tube MP2 is turned off. At this time, the current of the second current mirror I2 flows through the third PMOS tube MP3, the first capacitor C1 and the first PMOS tube MP1 in sequence. Since the first capacitor C1 is now in a stable charging state and will rise at a fixed slope, when the switching power supply circuit is in a discharging state, the signal output by the first voltage inverter (i.e., SW1) is high, the third PMOS tube MP3 is turned off, the signal output by the second voltage inverter is high (i.e., SW2), and the second PMOS tube MP2 is turned off. At this time, the loop for charging the first capacitor C1 by the second current mirror I2 is disconnected, and the first The capacitor C1 will work in a stable discharge state. When the switching power supply circuit is in a dormant state, the signal output by the first voltage inverter is high, the third PMOS tube MP3 is turned off, the signal output by the second voltage inverter is low, and the second PMOS tube MP2 is turned on. At this time, the loop for charging the first capacitor C1 by the second current mirror I2 is disconnected. Although the first capacitor C1 is still in a discharge state, since the discharge current flows through the first PMOS tube MP1 and the second PMOS tube MP2, the discharge current of the first capacitor C1 increases due to the conduction of the second PMOS. Therefore, the output voltage threshold signal will decrease with a larger slope, so that the third voltage comparator can more accurately judge the output charging signal, so that the switching power supply circuit can complete the conversion from the dormant state to the charging state in the intermittent conduction mode.

[0083] In one embodiment, the switch control driving circuit 2 includes:

[0084] A multiplexer 21, wherein a first input end of the multiplexer 21 is connected to an output end of the first feedback loop 3, and a second input end of the multiplexer 21 is connected to an output end of the second feedback loop 4, for outputting the charging signal received from the first feedback loop 3 or the second feedback loop 4;

[0085] An RS controller 22, wherein a first input terminal of the RS controller 22 is connected to an output terminal of the multiplexer 21, and is used for processing and generating a charging control signal and then outputting the charging control signal when receiving the charging signal;

[0086] The logic control and driver 23, the input end of the logic control and driver 23 is electrically connected to the output end of the RS controller 22, and the output end of the logic control and driver 23 is electrically connected to the controlled end of the switch circuit 1, and is used to process the received charging control signal to generate a charging drive signal to drive the switch circuit 1 to work in a charging state.

[0087] In this embodiment, the switch control driving circuit 2 receives the charging signals sent by the first feedback loop 3 and the second feedback loop 4 through the multiplexer 21, and after receiving the charging signals through the RS controller 22, processes and generates charging control signals and outputs them to the logic control and driver 23, so that the logic control and driver 23 processes and generates corresponding charging driving signals to drive the switch circuit 1 to switch to the charging state for operation, so that the switch power supply circuit enters the charging state.

[0088] Furthermore, the switching power supply circuit further includes:

[0089] A discharge state conversion circuit 5, wherein the input end of the discharge state conversion circuit 5 is electrically connected to the output end of the switch circuit 1, and the output end of the discharge state conversion circuit 5 is electrically connected to the second input end of the RS controller 22, and is used to send a discharge signal to the RS controller 22, and the RS controller 22 generates a discharge control signal and then outputs it to control the logic control and driver 23 to generate a discharge drive signal according to the discharge control signal, and drive the switch circuit 1 to work in a discharge state.

[0090] In this embodiment, the discharge state conversion circuit 5 includes a TON on-time generating circuit, a phase-locked loop and an RT circuit, the first end of the RT resistor is electrically connected to the output end of the switch circuit 1, the second end of the RT resistor is electrically connected to the input end of the phase-locked loop, the output end of the phase-locked loop is electrically connected to the CLK input end of the TON on-time generating circuit, the VIN input end of the TON on-time generating circuit is connected to an external power supply, the VOUT end of the TON on-time generating circuit is connected to the output end of the switch circuit 1, and the output end of the TON on-time generating circuit is electrically connected to the second input end of the RS controller 22.

[0091] Among them, when the switching power supply circuit enters the charging state, the TON conduction time generating circuit can be controlled to start working through the logic control and driver 23 or the external controller, and receive the external clock signal CLK obtained by the phase-locked loop debugging (the signal can be programmed by setting the resistance value of the RT resistor) and simultaneously receive the voltage of the external power supply VIN and the voltage VOUT output by the switching power supply circuit to the external load. At this time, the capacitor with an initial voltage of zero inside the TON conduction time generating circuit module begins to charge, and the charging current is proportional to the voltage of the external power supply VIN and inversely proportional to the RT resistor. When the capacitor is in the charging stage, the capacitor voltage rises steadily. At this time, the chip is in the charging stage, and the inductor current rises steadily. When the internal capacitor voltage rises to the set threshold, a discharge signal is output to the RS controller 22. The RS controller 22 generates a discharge control signal and then outputs it to control the logic control and driver 23 to generate a discharge drive signal according to the discharge control signal processing, and drive the switch circuit 1 to work in a discharge state, so as to control the switch circuit 1 from a charging working state to a discharging working state; such a setting enables the switching power supply circuit to work in an AOT control mode, and because when the switching power supply circuit enters a sleep state in the intermittent conduction mode, the TON conduction time generating circuit does not start working, which can effectively reduce the power consumption of the switching power supply circuit in the intermittent conduction mode.

[0092] Furthermore, the switching power supply circuit further includes:

[0093] A sleep state conversion circuit 6, wherein the negative input terminal of the sleep state conversion circuit 6 is connected to the inductor current sampling terminal, the positive input terminal of the sleep state conversion circuit 6 is connected to the switch circuit 1, and the output terminal of the sleep state conversion circuit 6 is electrically connected to the input terminal of the logic control and driver 23, and is used to generate a sleep control signal when it is detected that the inductor current is zero, so as to control the logic control and driver 23 to generate a sleep drive signal according to the sleep control signal, so as to drive the switch circuit 1 to work in the sleep state.

[0094] In this embodiment, the sleep state conversion circuit 6 can be implemented by a zero-crossing comparator. Since the inductor current always maintains 0 for a period of time in a switching cycle in the intermittent conduction mode, the zero-crossing comparator generates a sleep control signal when detecting that the inductor current is 0, so as to control the logic control and driver 23 to generate a sleep drive signal according to the sleep control signal processing, and drive the switch circuit 1 to work in the sleep state, thereby controlling the switch circuit 1 to enter the sleep working state from the discharge working state in the intermittent conduction mode.

[0095] Furthermore, the switch circuit 1 comprises:

[0096] a first switch tube MN, wherein a source of the first switch tube MN is connected to an external power supply, a gate of the first switch tube MN is electrically connected to an output end of the logic control and driver, and a drain of the first switch tube is electrically connected to the external load;

[0097] A second switch tube MP, wherein the source of the second switch tube MP is electrically connected to the drain of the first switch tube MN and the external load respectively, the gate of the second switch tube MP is electrically connected to the output end of the logic control and driver, and the drain of the second switch tube MP is electrically connected to the positive input end of the sleep state conversion circuit 6, wherein;

[0098] When the logic control and driver outputs a charging drive signal, the first switch tube MN is controlled to be turned on and the second switch tube MP is controlled to be turned off; or when the logic control and driver outputs a discharging drive signal, the first switch tube MN is controlled to be turned off and the second switch tube MP is controlled to be turned on; or when the logic control and driver outputs a sleep drive signal, the first switch tube MN and the second switch tube MP are controlled to be turned off.

[0099] In this embodiment, the first switch tube MN and the second switch tube MP can be implemented by transistors. When the switching power supply circuit is in the continuous conduction mode, the logic control and driver only need to output a charging drive signal and a discharging drive signal to complete the state conversion between charging and discharging in a switching cycle in the switching power supply circuit. When the switching power supply circuit is in the continuous conduction mode, the logic control and driver need to output a charging drive signal, a discharging drive signal and a sleeping drive signal to complete the state conversion between charging, discharging and sleeping in a switching cycle in the switching power supply circuit. Specifically, the first switch tube MN is a fourth PMOS tube, and the second switch tube MP is a first NMOS tube.

[0100] To facilitate the explanation of the technical principles of this solution, the following working process is provided for reference:

[0101] The working process of the DC-DC step-down power supply switch power supply circuit of the present invention working in the CCM (continuous conduction mode) state is combined with Figure 2 and Figure 4 The display is as follows:

[0102] When the first NMOS transistor MP is turned on and the fourth PMOS transistor MN is turned off, the switching power supply circuit enters the charging stage, and the inductor current starts to rise. At this time, the TON on-time generating circuit module 7 starts to work. The module receives the external clock signal CLK obtained by the phase-locked loop debugging (the frequency value of the signal can be programmed by setting the resistance value of the RT resistor), and receives the external working voltage VIN and the voltage VOUT of the external load.

[0103] At this time, a capacitor with an initial voltage of zero starts to charge inside the TON on-time generation circuit module. The charging current is proportional to the operating voltage VIN and inversely proportional to the resistance RT. When the capacitor is in the charging stage, the capacitor voltage rises steadily. At this time, the switching power supply circuit is in the charging stage, and the inductor current rises steadily. When the internal capacitor voltage rises to the voltage threshold VOUT of the load feedback, Figure 2 The signal sigoff receiving end (second input end) of the RS controller generates a high pulse (i.e., a charging signal), and the change of the signal is received by the logic control and driving module, generating a driving signal PG of high potential and a driving signal NG of high potential, so that the first NMOS tube MP is turned off and the fourth PMOS tube MN is turned on, and the charging stage of the switching power supply circuit ends and enters the discharging stage.

[0104] After entering the discharge phase, the inductor current begins to decrease. The voltage VOUT output to the load begins to decrease, causing the feedback voltage V FB This change is passed through the second feedback loop. Amplifier AMP1 converts V FB The reference voltage signal V provided by the reference circuit REF Amplify the result and input it into the first voltage comparator COMP1 for error comparison (due to the different working thresholds of comparator COMP2 and COMP1: the second voltage comparator COMP2 is at the feedback voltage V FB Rise to 605mV to work; when comparator COMP1 is working, the feedback voltage V FB Less than 605mV. The working states of COMP1 and COMP2 are mutually exclusive, and COMP2 does not work at this time). COMP1 outputs the error amplification result V ERR1 (i.e., the first voltage amplified signal). The current comparator ICMP compares the inductor sampling current I SW and V ERr1 , at this time I SW The change of V ErR1 The AC V is filtered by comparator COMP1 FB The output is obtained by amplification, so the change is relatively stable, mainly due to I SW Affects the output result of the current comparator ICMP. SW When it drops to the threshold, the output of the current comparator ICMP flips, and the sigon signal terminal (first input terminal) of the RS controller 22 generates a high pulse. The change of the signal is received by the logic control and driving module 23, and the driving signal PG is generated as a low potential, and the driving signal NG is generated as a low potential, so that the first NMOS tube MP is turned on and the fourth PMOS tube MN is turned off. The discharge phase of the switching power supply circuit ends and enters the charging phase.

[0105] The working process of the DC-DC step-down power supply switch power supply circuit of the present invention working in the DCM state is combined with Figure 2 and Figure 4 The display is as follows:

[0106] As the load current decreases, the capacitor C used in conjunction with the inductor OUT The output voltage VOUT is further increased by charging, and then fed back to the feedback voltage V FB Rising, when V FB When it rises to a certain threshold, it begins to enter the working range of the comparator COMP2. At this time, the logic control and drive module generates a logic control signal to turn off the first voltage comparator COMP1 and the current comparator ICMP in the second feedback loop in the CCM state. As the load current gradually decreases to close to 0, the working state of the switching power supply circuit begins to change from CCM to DCM. When the first NMOS tube MP is turned off, the fourth PMOS tube MN is turned on, and the switching power supply circuit works in the discharge stage, the inductor current sampling I SW The current continues to decrease until it reaches 0, and the output of the zero-crossing comparator COMP3 in the sleep state conversion circuit 6 flips, generating a zero current detection signal to be transmitted to the logic control and drive module, which generates a drive signal to turn off the MOS tubes MP and MN, and the switching power supply circuit enters the sleep stage (both the MOS tubes MP and MN are turned off).

[0107] In the dormant stage, the first voltage comparator COMP1, the current comparator ICMP and the fourth voltage comparator (zero-crossing detection comparator) COMP3 are all turned off. At this time, the feedback signal changes and flows through the second feedback loop path of the amplifier AMP1, the comparator COMP2, the comparator COMP4, etc. This strategy avoids the energy loss generated when these closed comparators are working, and only completes the function of the second feedback loop in which the second voltage comparator COMP2 participates by comparing the voltage, thereby reducing the power consumption of the overall operation of the switching power supply circuit.

[0108] Regarding the second feedback loop in which the comparator COMP2 participates, due to a certain delay in the response of the second feedback loop, the output voltage VOUT exhibits subharmonic oscillation. In order to further reduce the subharmonic oscillation phenomenon generated at this stage, a slope compensation voltage signal V is introduced into this loop. sIope , the voltage has a larger slope when it drops in the sleep phase, so that the third voltage comparator COMP4 can more accurately judge the moment of transition from the sleep phase to the charging phase. slope and COMP2 output V ERR2 , when V ERR2When it rises to the threshold, the output of the comparator COMP4 flips and generates a charging signal sigon. The logic control and driving module generates a corresponding driving signal to turn on the first NMOS tube MP and turn off the fourth PMOS tube MN, and the switching power supply circuit enters the charging state.

[0109] When the signal is transmitted in the second feedback loop, there is a certain time delay, which causes the voltage VOUT output to the load to be different from the output V of COMP2. ERR2 (V ERR2 There is a certain phase difference (see Figure 4 Medium V ERR2 If there is no phase difference, then in the sleep phase, the output voltage VOUT drops rapidly, corresponding to V ERR2 should rise rapidly, at which point comparator COMP4 only needs to ERR2 Compared with the preset comparator flip threshold, when V ERR2 When the voltage rises to the flip threshold, the output of comparator COMP4 flips, and then enters the charging phase. Due to the phase difference, during the sleep phase, V ERR2 There may be a valley value at this stage, namely V ERR2 It is possible that V will first drop and then rise during this phase. Since the switching power supply circuit has a short sleep time, if a constant comparison threshold is used, then V ERR2 The comparison threshold will be reached when V drops, rather than when it rises. This will cause the comparator COMP4 to flip early and enter the charging phase of the next cycle, thus causing subharmonic oscillation. Therefore, the slope compensation circuit 7 is introduced instead of using a constant comparison threshold, so that V ERR2 When the comparison threshold V slope (ie, the charging operation comparison signal) also drops, thereby preventing the comparator COMP4 from flipping over prematurely at this time.

[0110] Generates slope compensation voltage V slope The structure of the slope compensation circuit is as follows Figure 3 As shown, for the convenience of explanation, the first PMOS tube MP1 is collectively referred to as MP1, the second PMOS tube MP2 is collectively referred to as MP2, and the third PMOS tube MP3 is collectively referred to as MP3. MP1 and MP2 are PMOS tubes with the same parameters. The first current mirror I1 provides a bias current source I BIAS1 , the second current mirror I2 provides a bias current source I BIAS2 .

[0111] Signal SW1 controls the on and off of MP3. It is low in the charging stage of the switching power supply circuit and high in the discharging stage, that is, MP3 is on in the charging stage and off in the discharging stage. Signal SW2 controls the on and off of MP2. It is low only in the dormant stage of the switching power supply circuit and high in the rest of the time, that is, MP2 is on in the dormant stage and off in the rest of the time. Among them, signal SW1 is generated by the external first inverter connected to the inductor SW node, which can be obtained by inverting the gate signal in the second switch tube MN → performing a logical AND operation with the gate signal in the first switch tube MP → inverting Figure 3 The SW2 signal in the bias current source I BIAS1 The first capacitor C1 is charged, so that the PMOS transistor MP1 connected to the gate and the drain is in a critical conduction state. At this moment, the source voltage of the PMOS transistor MP1 is V slope The initial value of the bias current source I BIAS1 The current is small. Bias current source I BIAS2 Responsible for charging the first capacitor C1 so that V slope The rate of change is large over time. In the charging stage of the switching power supply circuit, the signal SW1 is low and MP3 is turned on; the signal SW2 is high and MP2 is turned off. At this time, the bias current source I BIAS2 The current flows through MP3, the first capacitor C1 and MP1. Since the first capacitor C1 is in a stable charging state, the internal voltage of the first capacitor C1 will rise at a fixed slope. In order to make the comparator COMP4 compare V slope and V ERR2 It can more accurately judge the moment of output reversal, so in the discharge stage of the switching power supply circuit V slope It decreases at a lower slope as a buffer, so that V slope It can decrease with a larger slope. In the discharge stage of the switching power supply circuit, the signal SW1 is high and MP3 is turned off; the signal SW2 is high and MP2 is turned off. At this time, the bias current source I BIAS2 The circuit for charging the first capacitor C1 is disconnected, and the first capacitor C1 is in a stable discharge state. The discharge current flows through MP1, wherein the internal voltage of the first capacitor C1 is C slope .

[0112] Assuming that the proportion of the discharge phase of the switching power supply circuit in a switching cycle T is D1, and the proportion of the dormancy phase in the cycle T is D2, then the proportion of the charging phase in the cycle T is D = 1-D1-D2. The descending slope Slope1 of the discharge phase is:

[0113] Slope1=D*I BIAS2 / C slope ;

[0114] In the dormant stage of the switching power supply circuit, the signal SW1 is high and MP3 is turned off; the signal SW2 is low and MP2 is turned on. BIAS2 The circuit for charging the first capacitor C1 is disconnected, and the first capacitor C1 will still be in a discharging state, and the discharging current flows through the MOS transistors MP1 and MP2. Due to the conduction of MP2, the discharging current of the first capacitor C1 increases, so V slope Decrease with a larger slope. The slope of the dormant phase is:

[0115] Slope2=2D*I BIAS2 / (1+D2)C slope ;

[0116] It can be seen that since D2<1, 2 / (1+D2)>1, Slope1 <Slope2。

[0117] The purpose of disclosing the embodiments is to help further understanding of the present invention, and those skilled in the art should understand it.

[0118] The present invention also proposes a power supply chip, which includes the switching power supply circuit described above. The specific structure of the switching power supply circuit refers to the above-mentioned embodiment. Since the power supply chip adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0119] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A switching power supply circuit, characterized in that: The switching power supply circuit has a continuous conduction mode and a discontinuous conduction mode, and the circuit comprises: A switch circuit, wherein an input end of the switch circuit is used to connect to an external power supply, and an output end of the switch circuit is used to connect to an external load; A switch control driving circuit is electrically connected to a controlled end of the switch circuit, and the switch control driving circuit is used to control the operation of the switch circuit; A first feedback loop, wherein an input end of the first feedback loop is electrically connected to an output end of the switch circuit, and an output end of the first feedback loop is electrically connected to a signal feedback end of the switch control drive circuit; a second feedback loop, wherein an input end of the second feedback loop is electrically connected to an output end of the switch circuit, and an output end of the second feedback loop is electrically connected to a signal feedback end of the switch control drive circuit; In the continuous conduction mode, the first feedback loop starts to work, and the first feedback loop processes the first voltage signal output by the switch circuit to generate a charging signal, and outputs the charging signal to the switch control drive circuit, so that the switch control drive circuit controls the switch circuit to work according to the charging signal; In the intermittent conduction mode, the second feedback loop starts working, and the second feedback loop processes the second voltage signal output by the switch circuit to generate a charging signal, and outputs it to the switch control drive circuit, so that the switch control drive circuit controls the operation of the switch circuit according to the charging signal.

2. The switching power supply circuit according to claim 1, characterized in that: The first feedback loop also includes a first voltage amplifier, wherein a positive input terminal of the first voltage amplifier is connected to a reference power supply electrical connection terminal, and a negative input terminal of the first voltage amplifier is electrically connected to an output terminal of the switch circuit, and is used for amplifying and outputting a first voltage signal and a reference voltage signal received as feedback from an external load; A first voltage comparator, wherein a negative input terminal of the first voltage comparator is electrically connected to a first output terminal of the first voltage amplifier, and a positive input terminal of the first voltage comparator is electrically connected to a second output terminal of the first voltage amplifier, and is configured to output a first voltage amplification signal when a first voltage signal of an external load after receiving the amplification is less than a reference voltage signal after the amplification; A current comparator, wherein the negative input terminal of the current comparator is connected to the inductor current sampling terminal, and the positive input terminal of the current comparator is electrically connected to the output terminal of the first voltage comparator, and is used to calculate according to the sampling current value sent by the inductor current sampling terminal and the first voltage amplification signal received, so as to output the charging signal to the switch control drive circuit when a preset charging threshold is reached.

3. The switching power supply circuit according to claim 1, characterized in that: The second feedback loop comprises: a second voltage amplifier, wherein the positive input terminal of the second voltage amplifier is connected to the reference power supply connection terminal, and the negative input terminal of the first voltage amplifier is connected to the output terminal of the switch circuit, and is used to receive the second voltage signal of the external load and the reference voltage signal, and output them after amplification; a second voltage comparator, wherein a negative input terminal of the second voltage comparator is electrically connected to a first output terminal of the second voltage amplifier, and a positive input terminal of the second voltage comparator is electrically connected to a second output terminal of the second voltage amplifier, and is configured to output a charging operation comparison signal when a second voltage signal of the external load after receiving the amplification is greater than a reference voltage signal; A third voltage comparator, wherein the negative input terminal of the third voltage comparator is electrically connected to the output terminal of the second voltage comparator, and the positive input terminal of the third voltage comparator is connected to the slope compensation circuit connection terminal, and is used to compare the received charging operation comparison signal with the slope compensation voltage signal sent by the slope compensation circuit, so as to output the charging signal to the switch control drive circuit when the slope compensation voltage signal is reached.

4. The switching power supply circuit according to claim 3, characterized in that: The switching power supply circuit also includes: A slope compensation circuit is electrically connected to the positive input terminal of the third voltage comparator and is used to provide a slope compensation voltage signal for preventing secondary harmonic oscillation.

5. The switching power supply circuit according to claim 4, characterized in that: The slope compensation circuit comprises: A first PMOS tube, a second PMOS tube, a third PMOS tube, a first current mirror, a second current mirror, a first capacitor and a working power supply connection terminal, wherein; The input end of the first current mirror and the input end of the second current mirror are electrically connected to the working power supply connection end respectively; the output end of the first current mirror is electrically connected to the source of the first PMOS tube, the first end of the first capacitor, the source of the second PMOS tube, the drain of the third PMOS tube and the positive input end of the third voltage comparator respectively; the output end of the second current mirror is electrically connected to the source of the third PMOS tube, the gate of the third PMOS tube is electrically connected to the output end of the first voltage inverter, the second end of the first capacitor, the gate of the first PMOS tube, the drain of the first PMOS tube and the drain of the second PMOS tube are grounded respectively, and the gate of the second PMOS tube is electrically connected to the output end of the second voltage inverter.

6. The switching power supply circuit according to claim 1, characterized in that: The switch control driving circuit comprises: a multiplexer, wherein a first input end of the multiplexer is connected to an output end of the first feedback loop, and a second input end of the multiplexer is connected to an output end of the second feedback loop, and is used to output the charging signal received from the first feedback loop or the second feedback loop; An RS controller, wherein a first input terminal of the RS controller is connected to an output terminal of the multiplexer, and is used for processing and generating a charging control signal and then outputting the charging control signal when receiving the charging signal; A logic control and driver, wherein the input end of the logic control and driver is electrically connected to the output end of the RS controller, and the output end of the logic control and driver is electrically connected to the controlled end of the switch circuit, and is used to process the received charging control signal to generate a charging drive signal to drive the switch circuit to operate in a charging state.

7. The switching power supply circuit according to claim 6, characterized in that: The switching power supply circuit also includes: A discharge state conversion circuit, wherein the input end of the discharge state conversion circuit is electrically connected to the output end of the switch circuit, and the output end of the discharge state conversion circuit is electrically connected to the second input end of the RS controller, and is used to send a discharge signal to the RS controller, and the RS controller generates a discharge control signal and then outputs it, so as to control the logic control and driver to generate a discharge drive signal according to the discharge control signal, and drive the switch circuit to work in a discharge state.

8. The switching power supply circuit according to claim 7, characterized in that: The switching power supply circuit also includes: A sleep state conversion circuit, wherein the negative input terminal of the sleep state conversion circuit is connected to the inductor current sampling terminal, the positive input terminal of the sleep state conversion circuit is connected to the switch circuit, and the output terminal of the sleep state conversion circuit is electrically connected to the input terminal of the logic control and driver, and is used to generate a sleep control signal when it is detected that the inductor current is zero, so as to control the logic control and driver to generate a sleep drive signal according to the sleep control signal, so as to drive the switch circuit to work in the sleep state.

9. The switching power supply circuit according to claim 8, characterized in that: The switch circuit comprises: a first switch tube, wherein a source of the first switch tube is connected to an external power supply, a gate of the first switch tube is electrically connected to an output end of the logic control and driver, and a drain of the first switch tube is electrically connected to the external load; A second switch tube, wherein the source of the second switch tube is electrically connected to the drain of the first switch tube and the external load respectively, the gate of the second switch tube is electrically connected to the output end of the logic control and driver, and the drain of the second switch tube is electrically connected to the positive input end of the sleep state conversion circuit, wherein; When the logic control and driver outputs a charging drive signal, the first switch tube is controlled to be turned on and the second switch tube is controlled to be turned off; when the logic control and driver outputs a discharging drive signal, the first switch tube is controlled to be turned off and the second switch tube is controlled to be turned on; when the logic control and driver outputs a sleep drive signal, the first switch tube and the second switch tube are controlled to be turned off.

10. A power chip, characterized in that: Comprising a switching power supply circuit as described in any one of claims 1 to 9.

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