DC conversion circuit, switching power supply and electronic equipment

Abstract

The present application is applicable to the field of electronic circuit technology, and provides a DC conversion circuit, a switching power supply and an electronic device. The circuit includes a current detection module, a driving module, a conversion module and a control module, the driving module is respectively connected to the current detection module, the conversion module and the control module, and the conversion module is respectively connected to the current detection module, the control module and the load. When the DC conversion circuit is in a light load state and works in a discontinuous conduction mode, the control module outputs a control signal according to the output voltage; the current detection module detects the first current flowing through the inductor, and when the first current is less than the second threshold, the first level signal is output, so that the driving module outputs the first drive signal according to the control signal, the first level signal and the clock signal, and controls the power tube to be turned on; when the first current is greater than or equal to the second threshold, the second level signal is output, so that the driving module outputs the second drive signal according to the control signal, the second level signal and the clock signal, and controls the power tube to be turned off.

Description

Technical Field

[0001] The present application belongs to the technical field of electronic circuits, and in particular relates to a direct current conversion circuit, a switching power supply and an electronic device. Background Art

[0002] The current switching power supply is required to achieve relatively high efficiency and energy saving and emission reduction in the full load range. In the light load state, a control method called "energy saving mode" is usually used to improve the efficiency of this state. The existing technology improves the efficiency in the light load state by controlling the power tube to be turned on multiple times in a cycle (the cycle is: the time interval between two consecutive times the power tube starts to be turned on in the non-energy saving mode). However, this method causes a large output voltage ripple because the number of times the power tube is controlled to be turned on in each cycle is large and the number of times is uncertain, and the power consumption of the circuit is high because the power tube is controlled to be turned on multiple times. Summary of the invention

[0003] The embodiments of the present application provide a DC conversion circuit, a switching power supply and an electronic device, which can solve the problems of large output ripple and high power consumption in the prior art.

[0004] In a first aspect, an embodiment of the present application provides a DC conversion circuit, including a current detection module, a drive module, a conversion module and a control module, wherein the drive module is respectively connected to the current detection module, the conversion module and the control module, and the conversion module is respectively connected to the current detection module, the control module and a load;

[0005] When the current of the load is less than a first threshold and the DC conversion circuit operates in a discontinuous conduction mode, the control module collects the output voltage of the conversion module, and outputs a control signal to the driving module according to the output voltage; the current detection module detects a first current flowing through the inductor in the conversion module, and when the first current is less than a second threshold, outputs a first level signal to the driving module, so that the driving module outputs a first drive signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to be turned on; when the first current is greater than or equal to the second threshold, outputs a second level signal to the driving module, so that the driving module outputs a second drive signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to be turned off.

[0006] In a possible implementation of the first aspect, the DC conversion circuit further includes a mode detection module, and the mode detection module is connected to the conversion module and the current detection module respectively;

[0007] When the current of the load is greater than or equal to the first threshold and the DC conversion circuit operates in the continuous conduction mode, the mode detection module outputs a third level signal to the current detection module according to the voltage at the switch node in the conversion module and the clock signal; the current detection module adjusts the second threshold to the third threshold according to the third level signal, and when the first current is less than the third threshold, outputs a first level signal to the drive module, so that the drive module outputs a first drive signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to be turned on; when the first current is greater than or equal to the third threshold, outputs a second level signal to the drive module, so that the drive module outputs a third drive signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to be turned on or off; wherein the third threshold is less than the second threshold.

[0008] In a possible implementation manner of the first aspect, when the current of the load is less than the first threshold and the DC conversion circuit operates in a discontinuous conduction mode, the mode detection module outputs a fourth level signal to the current detection module according to the voltage at the switch node in the conversion module and the clock signal; the current detection module adjusts the third threshold to the second threshold according to the fourth level signal, and when the first current is less than the second threshold, outputs a first level signal to the drive module, so that the drive module outputs a first drive signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to be turned on; when the first current is greater than or equal to the second threshold, outputs a second level signal to the drive module, so that the drive module outputs a second drive signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to be turned off.

[0009] In a possible implementation manner of the first aspect, the driving module includes a logic unit and a driving unit, the logic unit is connected to the current detection module, the control module and the driving unit respectively, and the driving unit is connected to the conversion module;

[0010] When the first current is less than a second threshold, the logic unit outputs a first logic signal to the driving unit according to the control signal, the first level signal and the clock signal; the driving unit outputs a first driving signal to the conversion module according to the first logic signal;

[0011] When the first current is greater than or equal to the second threshold, the logic unit outputs a second logic signal to the driving unit according to the control signal, the second level signal and the clock signal; and the driving unit outputs a second driving signal to the conversion module according to the second logic signal.

[0012] In a possible implementation manner of the first aspect, the logic unit includes a first inverter, a D flip-flop, a first AND gate, a second AND gate, a first NOR gate, a second NOR gate, and a second inverter, wherein an input end of the first inverter is respectively connected to the control module and a first input end of the second AND gate, a second input end of the second AND gate is connected to the current detection module, an output end of the first inverter is connected to an input end of the D flip-flop, a clock end of the D flip-flop and a first input end of the first AND gate are both used to receive the clock signal, an output end of the D flip-flop is connected to the second input end of the first AND gate, an output end of the first AND gate is connected to a first input end of the first NOR gate, an output end of the second AND gate is connected to a first input end of the second NOR gate, a second input end of the first NOR gate is connected to an output end of the second NOR gate, an output end of the first NOR gate is respectively connected to a second input end of the second NOR gate and an input end of the second inverter, and an output end of the second inverter is connected to the driving unit.

[0013] In a possible implementation manner of the first aspect, the control module includes a PWM controller, and the PWM controller is connected to the driving module, the conversion module, and the load respectively.

[0014] In a possible implementation manner of the first aspect, the mode detection module includes a mode detector, and the mode detector is connected to the transformation module and the current detection module respectively.

[0015] In a possible implementation of the first aspect, the conversion module includes an inductor, a power tube, a diode and a capacitor, the first end of the inductor receives an input voltage, the second end of the inductor is respectively connected to the drain of the power tube, the positive electrode of the diode, the current detection module and the mode detection module, the gate of the power tube is connected to the driving module, the source of the power tube is grounded, the cathode of the diode is respectively connected to the first end of the capacitor, the control module and the load, and the second end of the capacitor is grounded; wherein the switch node is a common end of the second end of the inductor and the drain of the power tube.

[0016] In a second aspect, an embodiment of the present application provides a switching power supply, comprising the DC conversion circuit described in any one of the first aspects.

[0017] In a third aspect, an embodiment of the present application provides an electronic device, comprising the DC conversion circuit described in any one of the first aspects.

[0018] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0019] An embodiment of the present application provides a DC conversion circuit, including a current detection module, a drive module, a conversion module and a control module, wherein the drive module is respectively connected to the current detection module, the conversion module and the control module, and the conversion module is respectively connected to the current detection module, the control module and the load.

[0020] When the current of the load is less than the first threshold value (indicating that the DC conversion circuit is in a light-load state) and the DC conversion circuit operates in the intermittent conduction mode, the control module collects the output voltage of the conversion module and outputs a control signal to the drive module according to the output voltage. The current detection module detects the first current flowing through the inductor in the conversion module. When the first current is less than the second threshold value, the first level signal is output to the drive module, so that the drive module outputs the first drive signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to turn on. When the first current is greater than or equal to the second threshold value, the second level signal is output to the drive module, so that the drive module outputs the second drive signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to turn off.

[0021] The current detection module in the present application outputs a corresponding level signal according to the magnitude of the first current, and determines the pulse width of the corresponding drive signal together with the control signal output by the control module. If the control signal requires turning off the power tube in the conversion module and causing the first current to decrease, if the first current is less than the second threshold, the first level signal output by the current detection module will prevent the control signal from turning off the power tube until the first current rises to be greater than or equal to the second threshold (that is, the current detection module outputs the second level signal), and then the control signal is allowed to turn off the power tube. As can be seen from the above, after the control signal turns on the power tube each time, the first current must be greater than or equal to the second threshold before the control signal is allowed to turn off the power tube, so that each switching action of the power tube has the minimum energy stored and transmitted to the output voltage. According to the principle of energy conservation, when the DC conversion circuit is in a light-load state, the control loop will reduce the switching frequency of the power tube so that the input energy is equal to the output energy, thereby reducing switching loss, driving loss, reverse recovery loss, etc., to improve the efficiency of the DC conversion circuit when it is in a light-load state.

[0022] In summary, in order to improve its efficiency under light load conditions, the DC conversion circuit provided in the embodiment of the present application reduces the switching loss, driving loss, reverse recovery loss, etc. of the power tube by reducing the number of switching times of the power tube. Compared with the prior art, the present application controls the power tube to be turned on only once within one cycle (the cycle is: the time interval between two consecutive times the power tube starts to be turned on in non-energy-saving mode) and the number of times the power tube is controlled to be turned on in each cycle is once, which not only reduces the ripple of the output voltage, but also reduces the power consumption of the circuit.

[0023] It can be understood that the beneficial effects of the second to third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 It is a principle block diagram of a DC conversion circuit provided in an embodiment of the present application;

[0026] Figure 2 The working waveform of the DC conversion circuit provided by an embodiment of the present application is shown in FIG. Figure 1 ;

[0027] Figure 3 is a principle block diagram of a DC conversion circuit provided in another embodiment of the present application;

[0028] Figure 4 The working waveform of the DC conversion circuit provided by an embodiment of the present application is shown in FIG. Figure 2 ;

[0029] Figure 5 is a principle block diagram of a DC conversion circuit provided in another embodiment of the present application;

[0030] Figure 6 1 is a circuit connection diagram of a DC conversion circuit provided in an embodiment of the present application;

[0031] Figure 7 The working waveform of the DC conversion circuit provided by an embodiment of the present application is shown in FIG. Figure 3 .

[0032] In the figure: 10, current detection module; 20, driving module; 21, logic unit; 22, driving unit; 30, conversion module; 40, control module; 41, PWM controller; 50, mode detection module; 51, mode detector; 60, load. DETAILED DESCRIPTION

[0033] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0034] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0035] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0036] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0037] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0038] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0039] The current switching power supply is required to achieve relatively high efficiency and energy saving and emission reduction in the full load range. In the light load state, a control method called "energy saving mode" is usually used to improve the efficiency of this state. There are different ways to implement the energy saving mode. The existing technology improves the efficiency in the light load state by controlling the power tube to be turned on multiple times in a cycle (the cycle is: the time interval between two consecutive times the power tube starts to be turned on in the non-energy saving mode). However, this method controls the power tube to be turned on a large number of times in each cycle and the number of times is uncertain, resulting in a large output voltage ripple, and the power consumption of the circuit is high because the power tube is controlled to be turned on multiple times, which

[0040] In view of the above problems, the embodiment of the present application provides a DC conversion circuit, and proposes a new energy-saving control method based on the circuit, such as Figure 1 As shown, the DC conversion circuit includes a current detection module 10, a drive module 20, a conversion module 30 and a control module 40, the drive module 20 is respectively connected to the current detection module 10, the conversion module 30 and the control module 40, and the conversion module 30 is respectively connected to the current detection module 10, the control module 40 and the load 60.

[0041] Specifically, when the current of the load 60 is less than the first threshold value (indicating that the DC conversion circuit is in a light-load state) and the DC conversion circuit operates in the intermittent conduction mode, the control module 40 collects the output voltage VOUT of the conversion module 30, and outputs a control signal (the control signal is a PWM control signal) to the driving module 20 according to the output voltage VOUT. The current detection module 10 detects the first current IL flowing through the inductor in the conversion module 30, and when the first current IL is less than the second threshold value Imin, outputs a first level signal (the first level signal is a low level) to the driving module 20, so that the driving module 20 outputs a first drive signal to the conversion module 30 according to the control signal, the first level signal and the clock signal CLK, and controls the power tube in the conversion module 30 to be turned on. When the first current IL is greater than or equal to the second threshold value Imin, outputs a second level signal (the second level signal is a high level) to the driving module 20, so that the driving module 20 outputs a second drive signal to the conversion module 30 according to the control signal, the second level signal and the clock signal CLK, and controls the power tube in the conversion module 30 to be turned off. It should be noted that the first threshold is a reference value for determining whether the DC conversion circuit is in a light load state. The specific value of the first threshold is not fixed and can be flexibly set according to factors such as actual application scenarios and circuit design requirements.

[0042] The current detection module 10 in the present application outputs a corresponding level signal according to the magnitude of the first current IL, and determines the pulse width of the corresponding driving signal together with the control signal output by the control module 40. If the control signal requires turning off the power tube in the conversion module 30 and causing the first current IL to decrease, if the first current IL is less than the second threshold value Imin, the first level signal output by the current detection module 10 will prevent the control signal from turning off the power tube until the first current IL increases to be greater than or equal to the second threshold value Imin (that is, the current detection module 10 outputs the second level signal), and then the control signal is allowed to turn off the power tube. As can be seen from the above, after the control signal turns on the power tube each time, the first current IL must be greater than or equal to the second threshold value Imin before the control signal is allowed to turn off the power tube, so that each switching action of the power tube has the minimum energy stored and transmitted to the output voltage. According to the principle of energy conservation, when the DC conversion circuit is in a light-load state, the control loop will reduce the switching frequency of the power tube so that the input energy is equal to the output energy, thereby reducing switching loss, driving loss, reverse recovery loss, etc., to improve the efficiency of the DC conversion circuit when it is in a light-load state.

[0043] In summary, in order to improve its efficiency under light load conditions, the DC conversion circuit provided in the embodiment of the present application reduces the switching loss, driving loss, reverse recovery loss, etc. of the power tube by reducing the number of switching times of the power tube. Compared with the prior art, the present application controls the power tube to be turned on only once within one cycle (the cycle is: the time interval between two consecutive times the power tube starts to be turned on in non-energy-saving mode) and the number of times the power tube is controlled to be turned on in each cycle is once, which not only reduces the ripple of the output voltage, but also reduces the power consumption of the circuit.

[0044] It should be noted that the current detection module 10 may adopt an inductor current detection circuit in an existing switching power supply, and the present application does not limit the specific structure of the current detection module 10 .

[0045] In some embodiments, in the energy-saving control method of the present application, when the current of the load 60 gradually increases to be greater than or equal to the first threshold value (indicating that the DC conversion circuit exits the light-load state) and the DC conversion circuit operates in the continuous conduction mode, it is easy to cause the circuit to fall into a stable state of 1 / 2 switching frequency, such as Figure 2 As shown in the right half of the figure, this changes the switching frequency in the continuous conduction mode. For the circuit, this will increase the ripple of the output voltage VOUT, which is unacceptable. In order to solve the above problem, the present application introduces a mode detection module 50 in the DC conversion circuit, as shown in the right half of the figure. Figure 3 As shown, the mode detection module 50 is connected to the transformation module 30 and the current detection module 10 respectively.

[0046] Specifically, when the current of the load 60 is greater than or equal to the first threshold value (indicating that the DC conversion circuit exits the light load state) and the DC conversion circuit operates in the continuous conduction mode, the mode detection module 50 outputs a third level signal (the third level signal is a low level) to the current detection module 10 according to the voltage at the switch node LX in the conversion module 30 and the clock signal CLK. The current detection module 10 adjusts the second threshold value Imin (which can also be represented by Imin_H) to the third threshold value Imin_L according to the third level signal, and outputs a first level signal (the first level signal is a low level) to the driving module 20 when the first current IL is less than the third threshold value Imin_L, so that the driving module 20 outputs a first driving signal to the conversion module 30 according to the control signal, the first level signal and the clock signal CLK, and controls the power tube in the conversion module 30 to be turned on. When the first current IL is greater than or equal to the third threshold value Imin_L, a second level signal (the second level signal is a high level) is output to the driving module 20, so that the driving module 20 outputs a third driving signal to the conversion module 30 according to the control signal, the second level signal and the clock signal CLK, and controls the power tube in the conversion module 30 to be turned on or off. The third threshold value Imin_L is less than the second threshold value Imin.

[0047] The mode detection module 50 introduced in the present application can determine the working mode of the DC conversion circuit according to the relationship between the switch node LX and the clock signal CLK. When the DC conversion circuit exits the light load state and works in the continuous conduction mode, the mode detection module 50 outputs a third level signal (the third level signal is a low level), so that the current detection module 10 adjusts the second threshold value Imin to the third threshold value Imin_L according to the third level signal. By lowering the threshold, it can be ensured that the circuit will not fall into the 1 / 2 switching frequency state when transitioning from the intermittent conduction mode to the continuous conduction mode.

[0048] When the first current IL is less than the third threshold value Imin_L, the first level signal output by the current detection module 10 will prevent the control signal from shutting down the power tube until the first current IL rises to a value greater than or equal to the third threshold value Imin_L (that is, the current detection module 10 outputs a second level signal), and then the control signal is allowed to control the switch state of the power tube. At this time, the control signal can control the switch state of the power tube according to the specific situation of the control loop. It should be noted that in the continuous conduction mode, when the first current IL rises to a value greater than or equal to the third threshold value Imin_L, the control signal does not directly control the power tube to shut down, but controls the switch state of the power tube according to the actual control loop, for example: Figure 4 As shown in the rightmost part of FIG. 1 , when the first current IL is greater than the third threshold value Imin_L, the power tube is still turned on.

[0049] After the mode detection module 50 is introduced in the present application, the process of the circuit jumping out of 1 / 2 switching frequency is as follows Figure 4 As shown. At time t1, the mode detection module 50 detects that the DC conversion circuit exits the intermittent conduction mode. After the tdly delay time (the tdly delay time is the time for the threshold conversion, which is set manually), at time t2, the current detection module 10 adjusts the second threshold Imin to the third threshold Imin_L. The third threshold Imin_L is less than the second threshold Imin. Therefore, in the next cycle, before the control signal becomes high, the level signal output by the current detection module 10 is flipped to a high level. At this time, the switching state of the power tube is only determined by the control signal, so that the circuit is forced to return to the normal switching frequency from 1 / 2 switching frequency.

[0050] It should be noted that the mode detection module 50 may adopt a mode detection circuit in an existing switching power supply, and the present application does not limit the specific structure of the mode detection module 50 .

[0051] In some embodiments, when the current of the load 60 is less than the first threshold value (indicating that the DC conversion circuit is in a light load state) and the DC conversion circuit operates in a discontinuous conduction mode, the mode detection module 50 outputs a fourth level signal (the fourth level signal is a high level) to the current detection module 10 according to the voltage at the switch node LX in the conversion module 30 and the clock signal CLK. The current detection module 10 adjusts the third threshold value Imin_L to the second threshold value Imin according to the fourth level signal, and when the first current IL is less than the second threshold value Imin, outputs a first level signal (the first level signal is a low level) to the driving module 20, so that the driving module 20 outputs a first driving signal to the conversion module 30 according to the control signal, the first level signal and the clock signal CLK, and controls the power tube in the conversion module 30 to turn on. When the first current IL is greater than or equal to the second threshold value Imin, outputs a second level signal (the second level signal is a high level) to the driving module 20, so that the driving module 20 outputs a second driving signal to the conversion module 30 according to the control signal, the second level signal and the clock signal CLK, and controls the power tube in the conversion module 30 to turn off.

[0052] When the DC conversion circuit is in a light load state and operates in a discontinuous conduction mode, the mode detection module 50 outputs a fourth level signal (fourth level signal), so that the current detection module 10 adjusts the third threshold value Imin_L to the second threshold value Imin according to the fourth level signal. When the first current IL is less than the second threshold value Imin, the first level signal output by the current detection module 10 will prevent the control signal from shutting down the power tube until the first current IL rises to a value greater than or equal to the second threshold value Imin (that is, the current detection module 10 outputs the second level signal), and then the control signal is allowed to shut down the power tube.

[0053] In some embodiments, Figure 3 As shown, the mode detection module 50 is also connected to the control module 40. When the DC conversion circuit is in a light load state and works in a discontinuous conduction mode, the mode detection module 50 outputs a fourth level signal (the fourth level signal is a high level) to the control module 40 according to the voltage at the switch node LX in the conversion module 30 and the clock signal CLK. The control module 40 turns off its internal non-essential components according to the fourth level signal to reduce the static current of the control module 40, reduce the static loss of the control module 40, and further improve the efficiency of the DC conversion circuit when it is in a light load state.

[0054] In some embodiments, Figure 5 As shown, the driving module 20 includes a logic unit 21 and a driving unit 22 . The logic unit 21 is respectively connected to the current detection module 10 , the control module 40 and the driving unit 22 , and the driving unit 22 is connected to the conversion module 30 .

[0055] Specifically, when the DC conversion circuit is in a light load state and operates in a discontinuous conduction mode, when the first current IL is less than the second threshold value Imin, the logic unit 21 outputs a first logic signal (the first logic signal is a high level) to the driving unit 22 according to the control signal, the first level signal (the first level signal is a low level) and the clock signal CLK. The driving unit 22 outputs a first driving signal to the conversion module 30 according to the first logic signal to control the power tube in the conversion module 30 to be turned on.

[0056] When the first current IL is greater than or equal to the second threshold value Imin, the logic unit 21 outputs a second logic signal (the second logic signal is a low level) to the driving unit 22 according to the control signal, the second level signal (the second level signal is a high level) and the clock signal CLK. The driving unit 22 outputs a second driving signal to the conversion module 30 according to the second logic signal to control the power tube in the conversion module 30 to turn off.

[0057] When the DC conversion circuit exits the light load state and operates in the continuous conduction mode, when the first current IL is less than the third threshold value Imin_L, the logic unit 21 outputs the first logic signal (the first logic signal is a high level) to the driving unit 22 according to the control signal, the first level signal (the first level signal is a low level) and the clock signal CLK. The driving unit 22 outputs the first driving signal to the conversion module 30 according to the first logic signal to control the power tube in the conversion module 30 to conduct.

[0058] When the first current IL is greater than or equal to the third threshold value Imin_L, the logic unit 21 outputs a third logic signal to the driving unit 22 according to the control signal, the first level signal (the first level signal is a low level) and the clock signal CLK. The driving unit 22 outputs a third driving signal to the conversion module 30 according to the third logic signal to control the power tube in the conversion module 30 to be turned on or off.

[0059] In some embodiments, Figure 6As shown, the logic unit 21 includes a first inverter INV1, a D flip-flop, a first AND gate AND1, a second AND gate AND2, a first NOR gate XOR1, a second NOR gate XOR2 and a second inverter INV2. The input end of the first inverter INV1 is respectively connected to the control module 40 and the first input end of the second AND gate AND2, the second input end of the second AND gate AND2 is connected to the current detection module 10, the output end of the first inverter INV1 is connected to the input end of the D flip-flop, and the clock end of the D flip-flop and the first input end of the first AND gate AND1 are both used to receive the clock signal CLK. The output end of the D flip-flop is connected to the second input end of the first AND gate AND1, the output end of the first AND gate AND1 is connected to the first input end of the first NOR gate XOR1, the output end of the second AND gate AND2 is connected to the first input end of the second NOR gate XOR2, the second input end of the first NOR gate XOR1 is connected to the output end of the second NOR gate XOR2, the output end of the first NOR gate XOR1 is respectively connected to the second input end of the second NOR gate XOR2 and the input end of the second inverter INV2, and the output end of the second inverter INV2 is connected to the driving unit 22.

[0060] Specifically, taking the DC conversion circuit in a light load state and working in a discontinuous conduction mode as an example, and combining Figure 7 , explaining the working principle of the logic unit 21. Figure 7As shown, when the PWM control signal is at a low level, the rising edge of the clock signal CLK triggers the signal net1 output by the D flip-flop to be at a high level, and the signal net1 and the clock signal CLK are ANDed by the first AND gate AND1 to generate a signal net2 that is the same as the clock signal CLK. Since the PWM control signal is at a low level at this time, the signal net3 after the PWM control signal and the signal MIN_IL (MIN_IL includes the first level signal and the second level signal) are ANDed is also at a low level, and the signal net4 output by the RS flip-flop composed of the first NOR gate NOR1 and the second NOR gate NOR2 is at a low level, and the signal net5 output by the second inverter INV2 is at a high level, and the signal net5 generates a high level drive signal (i.e., the first drive signal) through the drive unit 22 to drive the power tube in the conversion module 30 to turn on. After the power tube is turned on, the inductor current IL (i.e., the first current) in the conversion module 30 begins to rise. If the inductor current IL is less than the second threshold value I_min, the signal MIN_IL is always at a low level. Regardless of whether the PWM control signal at this time becomes a high level, the signal net3 is always at a low level, and the output of the RS trigger remains unchanged. The power tube remains in the on state until the inductor current IL increases to be greater than or equal to the second threshold value I_min, and the PWM control signal becomes a high level. Only then can the signal net3 turn high and turn off the power tube, so that each time the power tube is controlled to be turned on, the inductor current IL must reach the set second threshold value I_min before the power tube is allowed to be turned off. In this way, each time the power tube is turned on, the inductor can store more energy, reduce the number of switching times of the power tube, and improve the efficiency of the DC conversion circuit when it is in a light load state.

[0061] For example, Figure 6 As shown, the control module 40 includes a PWM controller 41 , and the PWM controller 41 is connected to the driving module 20 , the conversion module 30 , the mode detection module 50 and the load 60 respectively.

[0062] For example, Figure 6 As shown, the mode detection module 50 includes a mode detector 51, and the mode detector 51 is connected to the transformation module 30, the current detection module 10 and the control module 40 respectively.

[0063] For example, Figure 6As shown, the conversion module 30 includes an inductor L, a power tube NEFT, a diode D and a capacitor C. The first end of the inductor L receives the input voltage VIN, the second end of the inductor L is respectively connected to the drain of the power tube NEFT, the positive electrode of the diode D, the current detection module 10 and the mode detection module 50, the gate of the power tube NEFT is connected to the driving module 20, the source of the power tube NEFT is grounded, the cathode of the diode D is respectively connected to the first end of the capacitor C, the control module 40 and the load 60, and the second end of the capacitor C is grounded. Among them, the switch node LX is the common end of the second end of the inductor L and the drain of the power tube NEFT.

[0064] Combine the following Figure 6 The working principle of the present application is further explained by taking the conversion module 30 as a non-synchronous rectification boost converter as an example.

[0065] The inductor L, the power tube NEFT, the diode D and the capacitor C constitute a non-synchronous rectifier boost converter. The PWM controller 41 collects the output voltage VOUT and outputs a PWM control signal to the logic unit 21 in the driving module 20 according to the output voltage VOUT. The current detection module 10 detects the inductor current IL, compares it with the set threshold value, and outputs a signal MIN_IL to the logic unit 21 in the driving module 20. The signal MIN_IL and the PWM control signal jointly determine the conduction duty cycle of the power tube NFET. The mode detection module 50 determines the working mode of the DC conversion circuit according to the relationship between the clock signal CLK and the voltage at the switch node LX. When it is detected that the DC conversion circuit switches from the intermittent conduction mode to the continuous conduction mode, the mode detection module 50 outputs a third level signal (the third level signal is a low level) to the current detection module 10, so that the current detection module 10 adjusts the set threshold to the third threshold Imin_L; when it is detected that the DC conversion circuit switches from the continuous conduction mode to the discontinuous conduction mode, the mode detection module 50 outputs a fourth level signal (the fourth level signal is a high level) to the current detection module 10, so that the current detection module 10 adjusts the set threshold to the second threshold Imin; at the same time, the mode detection module 50 also outputs a fourth level signal to the PWM controller 41, so that the PWM controller 41 turns off its internal non-essential components according to the fourth level signal, so as to reduce the static current of the PWM controller 41, and further improve the efficiency of the DC conversion circuit when it is in a light load state.

[0066] It should be noted that the conversion module 30 may also be a synchronous rectification boost converter or a buck converter.

[0067] The embodiment of the present application also provides a switching power supply, including the DC conversion circuit described above. Since the switching power supply provided in the embodiment of the present application adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0068] The embodiment of the present application also provides an electronic device, including the DC conversion circuit described above. Since the electronic device provided by the embodiment of the present application adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0069] Exemplarily, the electronic device may be a household appliance or a digital product.

[0070] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0071] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A DC conversion circuit, characterized in that: It includes a current detection module, a driving module, a conversion module and a control module, wherein the driving module is connected to the current detection module, the conversion module and the control module respectively, and the conversion module is connected to the current detection module, the control module and the load respectively; When the current of the load is less than a first threshold and the DC conversion circuit operates in a discontinuous conduction mode, the control module collects the output voltage of the conversion module and outputs a control signal to the driving module according to the output voltage; The current detection module detects a first current flowing through the inductor in the conversion module, and when the first current is less than a second threshold, outputs a first level signal to the driving module, so that the driving module outputs a first driving signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to be turned on; when the first current is greater than or equal to the second threshold, outputs a second level signal to the driving module, so that the driving module outputs a second driving signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to be turned off; The DC conversion circuit further includes a mode detection module, which is connected to the conversion module and the current detection module respectively; When the current of the load is greater than or equal to the first threshold and the DC conversion circuit operates in the continuous conduction mode, the mode detection module outputs a third level signal to the current detection module according to the voltage at the switch node in the conversion module and the clock signal; the current detection module adjusts the second threshold to the third threshold according to the third level signal, and when the first current is less than the third threshold, outputs a first level signal to the drive module, so that the drive module outputs a first drive signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to be turned on; when the first current is greater than or equal to the third threshold, outputs a second level signal to the drive module, so that the drive module outputs a third drive signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to be turned on or off; wherein the third threshold is less than the second threshold.

2. The DC conversion circuit according to claim 1, characterized in that: When the current of the load is less than the first threshold and the DC conversion circuit operates in a discontinuous conduction mode, the mode detection module outputs a fourth level signal to the current detection module according to the voltage at the switch node in the conversion module and the clock signal; The current detection module adjusts the third threshold to the second threshold according to the fourth level signal, and when the first current is less than the second threshold, outputs a first level signal to the driving module, so that the driving module outputs a first driving signal to the conversion module according to the control signal, the first level signal and the clock signal, and controls the power tube in the conversion module to be turned on; when the first current is greater than or equal to the second threshold, outputs a second level signal to the driving module, so that the driving module outputs a second driving signal to the conversion module according to the control signal, the second level signal and the clock signal, and controls the power tube in the conversion module to be turned off.

3. The DC conversion circuit according to any one of claims 1 or 2, characterized in that: The driving module comprises a logic unit and a driving unit, the logic unit is respectively connected to the current detection module, the control module and the driving unit, and the driving unit is connected to the conversion module; When the first current is less than a second threshold, the logic unit outputs a first logic signal to the driving unit according to the control signal, the first level signal and the clock signal; The driving unit outputs a first driving signal to the conversion module according to the first logic signal; When the first current is greater than or equal to the second threshold, the logic unit outputs a second logic signal to the driving unit according to the control signal, the second level signal and the clock signal; and the driving unit outputs a second driving signal to the conversion module according to the second logic signal.

4. The DC conversion circuit according to claim 3, characterized in that: The logic unit includes a first inverter, a D flip-flop, a first AND gate, a second AND gate, a first NOR gate, a second NOR gate and a second inverter, wherein the input end of the first inverter is respectively connected to the control module and the first input end of the second AND gate, the second input end of the second AND gate is connected to the current detection module, the output end of the first inverter is connected to the input end of the D flip-flop, the clock end of the D flip-flop and the first input end of the first AND gate are both used to receive the clock signal, the output end of the D flip-flop is connected to the second input end of the first AND gate, the output end of the first AND gate is connected to the first input end of the first NOR gate, the output end of the second AND gate is connected to the first input end of the second NOR gate, the second input end of the first NOR gate is connected to the output end of the second NOR gate, the output end of the first NOR gate is respectively connected to the second input end of the second NOR gate and the input end of the second inverter, and the output end of the second inverter is connected to the driving unit.

5. The DC conversion circuit according to any one of claims 1 or 2, characterized in that: The control module includes a PWM controller, and the PWM controller is connected to the driving module, the conversion module and the load respectively.

6. The DC conversion circuit according to claim 1 or 2, characterized in that: The mode detection module includes a mode detector, and the mode detector is connected to the conversion module and the current detection module respectively.

7. The DC conversion circuit according to any one of claims 1 or 2, characterized in that: The conversion module includes an inductor, a power tube, a diode and a capacitor, the first end of the inductor receives an input voltage, the second end of the inductor is respectively connected to the drain of the power tube, the positive electrode of the diode, the current detection module and the mode detection module, the gate of the power tube is connected to the driving module, the source of the power tube is grounded, the cathode of the diode is respectively connected to the first end of the capacitor, the control module and the load, and the second end of the capacitor is grounded; wherein the switch node is the common end of the second end of the inductor and the drain of the power tube.

8. A switching power supply, characterized in that: It comprises the DC conversion circuit as described in any one of claims 1 to 7.

9. An electronic device, characterized in that: It comprises the DC conversion circuit as described in any one of claims 1 to 7.

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