Driving control circuit and switching power supply

Abstract

The invention relates to a driving control circuit and a switching power supply, the driving control circuit comprises a current sampling circuit and a light-load wave sealing circuit, the current sampling circuit is electrically connected with the light-load wave sealing circuit, the current sampling circuit samples current flowing through a load to obtain sampling current, and when the sampling current is greater than a current threshold value, the light-load wave sealing circuit is electrically connected with the light-load wave sealing circuit; the light-load wave sealing circuit outputs a first control signal to enable the second group of switching tubes to work based on a received second driving signal, so that the switching power supply rapidly quits the light-load wave sealing state, the current-carrying capacity of the switching power supply is rapidly improved, and when the sampling current is smaller than or equal to a current threshold value, the switching power supply is switched off. And the light-load wave sealing circuit outputs a second control signal to drive the second group of switching tubes to stop working, so that the second group of switching tubes are ensured to be closed in a light-load state, the switching loss during light load is effectively reduced, and the light-load energy efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of switching power supplies, and in particular to a drive control circuit and a switching power supply. Background Art

[0002] When the equipment is running under light load, the switching power supply turns off some power switch tubes and operates in a light load blocking state, which greatly reduces switching losses and significantly improves the light load performance of the equipment.

[0003] However, if a sudden load or a more serious short-circuit fault occurs during the light-load blocking period, if the closed switch tube cannot be quickly restored, the current carrying capacity of the switching power supply will not be able to meet the load requirements, the equipment operation will be unreliable, and the safety will be low. Summary of the invention

[0004] The embodiments of the present application aim to provide a drive control circuit and a switching power supply, which can ensure the current carrying capacity of the switching power supply and achieve light load and low power consumption.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a drive control circuit, which is applied to a switching power supply, wherein the switching power supply includes a first group of switch tubes and a second group of switch tubes, wherein the first group of switch tubes works based on a received first drive signal, and the drive control circuit includes: a current sampling circuit and a light-load wave-enclosing circuit, wherein the current sampling circuit is electrically connected to the light-load wave-enclosing circuit;

[0007] The current sampling circuit is used to sample the current flowing through the load to obtain the sampled current;

[0008] The light-load wave-capping circuit is used to output a first control signal in response to the result that the sampled current is greater than the current threshold, so as to make the second group of switch tubes work based on the received second drive signal;

[0009] And in response to the result that the sampling current is less than or equal to the current threshold, a second control signal is output to drive the second group of switch tubes to stop working.

[0010] In some embodiments, the sampled current includes an instantaneous current and a steady-state current, and the current threshold includes a first current threshold and a second current threshold;

[0011] The light-load wave-capping circuit is used to respond to the result that the instantaneous current is less than or equal to the first current threshold and the steady-state current is less than or equal to the second current threshold, output the second control signal to drive the second group of switch tubes to stop working, otherwise, output the first control signal to make the second group of switch tubes work based on the received second drive signal.

[0012] In some embodiments, the light load wave sealing circuit includes: a first comparison unit, a second comparison unit and a NAND gate;

[0013] The first comparison unit is electrically connected to the current sampling circuit and the first input terminal of the NAND gate respectively, the second comparison unit is electrically connected to the current sampling circuit and the second input terminal of the NAND gate respectively, and the output terminal of the NAND gate is used to output the first control signal or the second control signal;

[0014] The first comparison unit is used to output a low-level first comparison signal in response to a result that the instantaneous current is greater than the first current threshold, and to output a high-level first comparison signal in response to a result that the instantaneous current is less than or equal to the first current threshold;

[0015] The second comparison unit is used to output a low-level second comparison signal in response to a result that the steady-state current is greater than the second current threshold, and to output a high-level second comparison signal in response to a result that the steady-state current is less than or equal to the second current threshold;

[0016] The NAND gate is used for responding to the input of the first comparison signal and the second comparison signal, and outputting the first control signal or the second control signal.

[0017] In some embodiments, the light-load wave-sealing circuit further includes: a steady-state current generating unit;

[0018] The steady-state current generating unit is electrically connected to the current sampling circuit and the second comparing unit respectively, and is used for generating and outputting the steady-state current in response to the input of the sampling current.

[0019] In some embodiments, the drive control circuit further includes: a chopper circuit;

[0020] The chopper circuit is electrically connected to the current sampling circuit, the first group of switch tubes and the second group of switch tubes respectively. The chopper circuit is used to respond to the result that the sampling current is greater than the overcurrent threshold, output a first stop signal to drive the first group of switch tubes to stop working, and output a second stop signal to drive the second group of switch tubes to stop working.

[0021] In some embodiments, the chopping circuit includes a third comparison unit and an AND gate;

[0022] The third comparison unit is electrically connected to the current sampling circuit and the first input terminal of the AND gate respectively, and the second input terminal of the AND gate is used to receive the first control signal or the second control signal;

[0023] The third comparison unit is used to respond to the result that the sampling current is greater than the overcurrent threshold value, and output the first stop signal to drive the first group of switch tubes to stop working. The AND gate is used to respond to the input of the first stop signal, and output the second stop signal to drive the second group of switch tubes to stop working.

[0024] In some embodiments, the drive control circuit further includes: a first controller and a second controller;

[0025] The first controller is used to output the first drive signal. When the enable end of the second controller is connected to the first control signal, the output end of the second controller outputs the second drive signal. When the enable end of the second controller is connected to the second control signal, the second controller drives the second group of switch tubes to stop working.

[0026] In some embodiments, the current sampling circuit includes: a sampling unit and a conversion unit;

[0027] The sampling unit is electrically connected to the conversion unit, which is electrically connected to the light-load wave-enclosing circuit. The sampling unit is used to sample the current flowing through the load, and the conversion unit is used to convert the current flowing through the load into a positive current to obtain and output the sampled current.

[0028] In some embodiments, the first current threshold is greater than the second current threshold.

[0029] In a second aspect, an embodiment of the present application provides a switching power supply, comprising a first group of switching tubes, a second group of switching tubes, and a drive control circuit as described above, wherein the first group of switching tubes operates based on the first drive signal received, and the drive control circuit is used to output the first control signal to enable the second group of switching tubes to operate based on the second drive signal received, and to output the second control signal to drive the second group of switching tubes to stop working.

[0030] In various embodiments of the present application, the drive control circuit includes a current sampling circuit and a light-load wave-sealing circuit. The current sampling circuit is electrically connected to the light-load wave-sealing circuit. The current sampling circuit samples the current flowing through the load to obtain a sampling current. When the sampling current is greater than the current threshold, the light-load wave-sealing circuit outputs a first control signal to enable the second group of switch tubes to operate based on the received second drive signal, so that the switching power supply quickly exits the light-load wave-sealing state and quickly improves the current-carrying capacity of the switching power supply. Moreover, when the sampling current is less than or equal to the current threshold, the light-load wave-sealing circuit outputs a second control signal to drive the second group of switch tubes to stop working, ensuring that the second group of switch tubes are turned off under the light-load state, effectively reducing the switching loss under light-load and improving the light-load energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0032] Figure 1 It is a structural schematic diagram of one of the switching power supplies provided in the embodiment of the present application;

[0033] Figure 2 is a structural schematic diagram of one of the drive control circuits provided in an embodiment of the present application;

[0034] Figure 3 is a structural schematic diagram of one of the drive control circuits provided in an embodiment of the present application;

[0035] Figure 4 is a structural schematic diagram of one of the drive control circuits provided in an embodiment of the present application;

[0036] Figure 5 is a schematic diagram of a circuit structure of a first comparison unit provided in an embodiment of the present application;

[0037] Figure 6 It is a schematic diagram of the circuit structure of one of the isolation units, the steady-state current generating unit and the second comparing unit provided in an embodiment of the present application;

[0038] Figure 7 It is a circuit structure diagram of a NAND gate and an AND gate provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] See also Figure 1 , Figure 1 is a schematic diagram of the structure of a switching power supply provided in an embodiment of the present application, such as Figure 1 As shown, the switching power supply includes an inductor L1, a first group of switch tubes 1 and a second group of switch tubes 2, wherein the first group of switch tubes 1 includes at least one upper tube and at least one lower tube, and the second group of switch tubes 2 includes at least one upper tube and at least one lower tube. Figure 1In the example, the second group of switch tubes 2 includes two upper tubes (MOS tube Q1 and MOS tube Q2) and two lower tubes (MOS tube Q4 and MOS tube Q6), and the first group of switch tubes 1 includes one upper tube (MOS tube Q3) and one lower tube (MOS tube Q6). The upper tubes in each group of switch tubes are power tubes, and the lower tubes in each group of switch tubes are synchronous tubes. In another embodiment, the first group of switch tubes may include two upper tubes and two lower tubes, and the second switch tube may include one upper tube and one lower tube. The specific number of upper tubes and lower tubes of the first group of switch tubes and the second group of switch tubes can be set according to actual needs.

[0041] The control end of the first group of switch tubes 1 receives a first drive signal, which is a PWM signal, and is used to control the conduction or cutoff of the upper tube and the lower tube, so that the first group of switch tubes 1 works. The control end of the second group of switch tubes 2 receives a second drive signal, which is a PWM signal, and is used to control the conduction or cutoff of the upper tube and the lower tube, so that the second group of switch tubes 2 works. The first drive signal and the second drive signal can be output by the controller or by the drive circuit.

[0042] When the first group of switch tubes 1 and / or the second group of switch tubes 2 are working, the power supply voltage is converted, and the converted voltage is output through the inductor L1 to provide a stable DC voltage for the load.

[0043] It should be noted that Figure 1 In the embodiment, two groups of switch tubes are used as an example. In other embodiments, the switch power supply can also have more than two groups of switch tubes, and the number of groups of switch tubes is set according to needs. The following embodiments all take the switch power supply including the first group of switch tubes 1 and the second group of switch tubes 2 as an example to describe the working process of the drive control circuit.

[0044] When the switching power supply is lightly loaded, the first group of switch tubes 1 is generally controlled to work based on the received first drive signal, and the second group of switch tubes 2 are controlled to stop working. The first group of switch tubes 1 converts the power supply voltage to provide a stable DC voltage for the load. The switching power supply is in a light-load blocking state, which greatly reduces the switching loss and significantly improves the light-load performance of the equipment.

[0045] However, if a sudden load or a more serious short-circuit fault occurs during the light-load blocking period, if the closed switch tube cannot be quickly restored, the current carrying capacity of the switching power supply will not be able to meet the load requirements.

[0046] Based on the above reasons, an embodiment of the present application provides a drive control circuit that can reduce switching losses in a light-load state and ensure the current carrying capacity of the switching power supply when a sudden load is added.

[0047] like Figure 2As shown, the driving control circuit 100 includes a current sampling circuit 10 and a light-load wave-enclosing circuit 20 , wherein the current sampling circuit 10 is electrically connected to the light-load wave-enclosing circuit 20 .

[0048] The current sampling circuit 10 samples the current flowing through the load to obtain a sampled current. The sampled current represents the current required by the load. A larger sampled current represents an increase in the current required by the load, and a smaller sampled current represents a smaller current required by the load, and a light load state.

[0049] The current sampling circuit 10 can be implemented by a sampling resistor, a differential amplifier, etc., and can also be implemented by a current sensor, such as a Hall sensor.

[0050] The sampled current is transmitted to the light load wave envelope circuit 20, and is received and analyzed by the light load wave envelope circuit 20. When the sampled current is greater than the current threshold, the light load wave envelope circuit 20 outputs a first control signal to enable the second group of switch tubes 2 to operate based on the received second drive signal.

[0051] Specifically, when the sampling current is greater than the current threshold, it indicates that the current required by the load has increased, or that a transient large current appears at the load end. The light-load wave-capping circuit 20 outputs a first control signal, and the first control signal is a low-level signal, or a high-level signal, so that the second drive signal acts on the control end of the second group of switch tubes 2. The second drive signal drives each switch tube in the second group of switch tubes 2 to be turned on or off, and then the second group of switch tubes 2 and the first group of switch tubes 1 jointly convert the power supply voltage, and the switching power supply outputs a larger and more stable DC voltage.

[0052] The second drive signal is a PWM signal, which is output by a controller that controls the second group of switch tubes 2 or output by a drive circuit that drives the second group of switch tubes 2, and the embodiment of the present application does not limit this. For example: the light-load wave-capping circuit 20 outputs a first control signal, and the controller that controls the second group of switch tubes 2 receives the first control signal, or detects the first control signal, and then outputs a second drive signal, and the second drive signal acts on the control end of the second group of switch tubes 2 to control the conduction or cutoff of the upper tube and the lower tube in the second group of switch tubes 2, thereby completing the conversion of the power supply voltage.

[0053] Therefore, when the load is in a high current condition, the light load wave blocking circuit 20 can respond quickly and quickly restore the drive enable of the second group of switch tubes that are blocked, so that the switching power supply quickly exits the light load wave blocking state, quickly improves the current carrying capacity of the switching power supply, ensures the overload capacity of the switching power supply, and thereby ensures the reliable and safe operation of the switching power supply.

[0054] When the sampling current is less than or equal to the current threshold, it indicates that the current required by the load is small and the load is currently in a light-load state. The light-load wave-sealing circuit 20 outputs a second control signal to drive the second group of switch tubes 2 to stop working. Only the first group of switch tubes 1 works based on the received first drive signal to achieve power supply voltage conversion and provide a stable DC voltage for the load. On the basis of ensuring the current carrying capacity required by the load, the switching power supply enters a light-load wave-sealing state, reduces switching losses, and improves light-load energy efficiency.

[0055] Similarly, the second control signal is a low-level signal or a high-level signal. The second control signal can directly act on the second group of switch tubes 2 to control the second group of switch tubes 2 to stop working. It can also be received by a controller that controls the second group of switch tubes 2 or by a drive circuit that drives the second group of switch tubes 2, and then the corresponding controller or the corresponding drive circuit drives the second group of switch tubes 2 to stop working. For example: the light-load wave-capping circuit 20 outputs the second control signal, and the controller that controls the second group of switch tubes 2 receives the second control signal or detects the second control signal, and then drives the second group of switch tubes 2 to stop working.

[0056] In summary, the drive control circuit can not only effectively reduce the switching loss under light load and improve the light load energy efficiency, but also enable the switching power supply to quickly exit the light load blocking state when a sudden load or short circuit fault occurs and other high current conditions, thereby quickly improving the current carrying capacity of the switching power supply and ensuring the overload capacity of the switching power supply.

[0057] In some embodiments, the first group of switch tubes 1 and the second group of switch tubes 2 are driven by different controllers. Specifically, Figure 3 As shown, the drive control circuit 100 also includes a first controller 30 and a second controller 40, wherein the first controller 30 outputs a first drive signal, the first group of switch tubes 1 operates based on the received first drive signal, the enable end of the second controller 40 is electrically connected to the output end of the light-load wave-capping circuit 20, and the output end of the second controller 40 is electrically connected to the control end of the second group of switch tubes 2.

[0058] When the enable terminal of the second controller 40 is connected to the first control signal, the output terminal of the second controller 40 outputs the second drive signal, so that the second group of switch tubes 2 work based on the second drive signal. When the enable terminal of the second controller 40 is connected to the second control signal, the output terminal of the second controller 40 outputs a stop signal, which drives the second group of switch tubes 2 to stop working.

[0059] In some embodiments, the first drive signal can be output by the first drive circuit, and the second drive signal and the stop signal can be output by the second drive circuit. The working process is similar to the working process of the first controller 30 and the second controller 40, and will not be repeated here.

[0060] In some embodiments, Figure 4 As shown, the current sampling circuit 10 includes a sampling unit 101 and a conversion unit 102, wherein the sampling unit 101 is electrically connected to the conversion unit 102, and the conversion unit 102 is electrically connected to the light load wave envelope circuit 20. The sampling unit 101 samples the current flowing through the load, and the conversion unit 102 converts the current flowing through the load into a positive current to obtain and output the sampled current.

[0061] The conversion unit 102 may be implemented by an absolute value circuit, such as a rectifier circuit, or a combination of a rectifier circuit and an amplifier circuit.

[0062] In the embodiment of the present application, the sampling current is a positive current, which makes the setting of the current threshold more convenient, and only a positive current threshold needs to be set.

[0063] In some embodiments, the sampling current includes an instantaneous current and a steady-state current, and the current threshold includes a first current threshold and a second current threshold. If the instantaneous current is less than or equal to the first current threshold, and the steady-state current is less than or equal to the second current threshold, it is determined that the sampling current is less than or equal to the current threshold, and the light-load wave-encapsulation circuit 20 outputs a second control signal to drive the second group of switch tubes 2 to stop working. If the instantaneous current is greater than the first current threshold and / or the steady-state current is greater than the second current threshold, it is determined that the sampling current is greater than the current threshold, and the light-load wave-encapsulation circuit 20 outputs a first control signal to make the second group of switch tubes 2 work based on the received second drive signal.

[0064] In the embodiment of the present application, the size of the sampling current is jointly determined by the instantaneous current and the steady-state current. When either the instantaneous current or the steady-state current is greater than the corresponding current threshold, it is considered that a large current condition has occurred or the current required by the load has increased, so that the light-load wave-capping circuit 20 can respond quickly and promptly improve the current-carrying capacity of the switching power supply.

[0065] The instantaneous current and the steady-state current are judged by the comparison unit, and the comparison result output by the comparison unit represents the magnitude of the instantaneous current and the steady-state current. Figure 4 As shown, the light-load wave-capping circuit 20 includes a first comparison unit 201, a second comparison unit 202 and a NAND gate 205, wherein the first comparison unit 201 is electrically connected to the current sampling circuit 10 and the first input terminal of the NAND gate 205, respectively, the second comparison unit 202 is electrically connected to the current sampling circuit 10 and the second input terminal of the NAND gate 205, respectively, and the output terminal of the NAND gate 205 is used to output the first control signal or the second control signal.

[0066] If the instantaneous current is greater than the first current threshold, the first comparison unit 201 outputs a low-level first comparison signal; if the instantaneous current is less than or equal to the first current threshold, the first comparison unit 201 outputs a high-level first comparison signal.

[0067] If the steady-state current is greater than the second current threshold, the second comparison unit 202 outputs a second comparison signal of a low level. If the steady-state current is less than or equal to the second current threshold, the second comparison unit 202 outputs a second comparison signal of a high level.

[0068] The NAND gate 205 responds to the input of the first comparison signal and the second comparison signal and outputs the first control signal or the second control signal. Specifically, if the first comparison signal is low level and / or the second comparison signal is low level, the NAND gate 205 outputs the first control signal, otherwise, the NAND gate 205 outputs the second control signal.

[0069] The first comparison unit 201 and the second comparison unit 202 can be comparators that respond immediately or hysteresis comparators. The use of hysteresis comparators can avoid the light-load wave-capping circuit 20 from frequently switching between the first control signal and the second control signal, thereby avoiding the second group of switch tubes 2 from frequently switching between working and stopping.

[0070] In some embodiments, please refer to Figure 4 The light-load wave-encapsulating circuit 20 further includes a steady-state current generating unit 204 , wherein the steady-state current generating unit 204 is electrically connected to the current sampling circuit 10 and the second comparing unit 202 , respectively.

[0071] The sampling current is input to the input terminal of the steady-state current generating unit 204 . The steady-state current generating unit 204 generates a steady-state current from the sampling current and transmits the steady-state current to the second comparing unit 202 .

[0072] The sampled current is the real-time current flowing through the load, which is composed of the current at each moment, and therefore, the steady-state current can only be obtained by passing through the steady-state current generating unit 204. In the embodiment of the present application, the steady-state current generating unit 204 is implemented by a filter circuit.

[0073] In some embodiments, please refer to Figure 4 The drive control circuit 100 further includes a chopper circuit 50, which is electrically connected to the current sampling circuit 10, the first group of switch tubes, and the second group of switch tubes. In some embodiments, the chopper circuit 50 is electrically connected to the current sampling circuit 10, the first controller 30, and the second controller 40, respectively. The first controller 30 is electrically connected to the first group of switch tubes, and the second controller 40 is electrically connected to the second group of switch tubes. Figure 4 The above connection method is shown in FIG.

[0074] If the sampled current is greater than the overcurrent threshold, the chopper circuit 50 outputs a first stop signal to drive the first group of switch tubes 1 to stop working, and the chopper circuit 50 outputs a second stop signal to drive the second group of switch tubes 2 to stop working.

[0075] Among them, when the sampling current is greater than the overcurrent threshold, it indicates that the load has an overcurrent phenomenon. The chopper circuit 50 drives the first group of switch tubes 1 to stop working through a first stop signal, and drives the second group of switch tubes 2 to stop working through a second stop signal. All power switch tubes are turned off to achieve chopper protection.

[0076] like Figure 4 As shown, the chopping circuit 50 includes a third comparing unit 501 and an AND gate 502, wherein the third comparing unit 501 is electrically connected to the current sampling circuit 10, the first input end of the AND gate 502 and the first controller 30 respectively, and the second input end of the AND gate 502 is used to receive the first control signal or the second control signal.

[0077] If the sampled current is greater than the overcurrent threshold, the third comparison unit 501 outputs a first stop signal, which acts on the control end of the first group of switch tubes 1 to drive the first group of switch tubes 1 to stop working. The AND gate 502 responds to the input of the first stop signal and outputs a second stop signal, which acts on the control end of the second group of switch tubes 2 to drive the second group of switch tubes 2 to stop working.

[0078] If the sampling current is less than or equal to the overcurrent threshold, the third comparison unit 501 outputs a first start signal, the first start signal causes the first controller 30 to output a first drive signal, and the first group of switch tubes 1 works based on the received first drive signal. In addition, the AND gate 502 responds to the input of the first start signal and the first control signal, outputs a second start signal, the second start signal causes the second controller 40 to output a second drive signal, and the second group of switch tubes 2 works based on the received second drive signal. The AND gate 502 responds to the input of the first start signal and the second control signal, outputs a second stop signal, and the second stop signal causes the second controller 40 to drive the second group of switch tubes 2 to stop working.

[0079] It should be noted that the embodiment of the present application takes the example that the first controller 30 outputs the first drive signal and the second controller 40 outputs the second drive signal. In other embodiments, both the first drive signal and the second drive signal can be output by the drive circuit, and the second stop signal can directly act on the control end of the second group of switch tubes to stop them from working.

[0080] In an embodiment of the present application, if the sampling current exceeds the overcurrent threshold, both the first group of switch tubes 1 and the second group of switch tubes 2 stop working to achieve chopping protection. If the sampling current does not exceed the overcurrent threshold, the AND gate 502 controls the second group of switch tubes 2 to work normally based on the first control signal, and controls the second group of switch tubes 2 to stop working based on the second control signal.

[0081] See also Figure 5 , Figure 5 is a schematic diagram of a circuit structure of a first comparison unit provided in an embodiment of the present application, such as Figure 5 As shown, the first comparison unit 201 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first capacitor C1, a second capacitor C2, a first hysteresis comparator U1.1 and a first diode D1.

[0082] One end of the second resistor R2 is connected to the output signal I_I N of the absolute value circuit (not shown in the figure), the other end of the second resistor R2 is respectively connected to one end of the first capacitor C1 and the inverting input end of the first hysteresis comparator U1.1, and the other end of the first capacitor C1 is grounded.

[0083] One end of the third resistor R3 is connected to the reference voltage signal, and the other end of the third resistor R3 is respectively connected to one end of the fifth resistor R5, one end of the sixth resistor R6, one end of the second capacitor C2, one end of the seventh resistor R7 and the in-phase input end of the first hysteresis comparator U1.1, and the other end of the fifth resistor R5, the other end of the sixth resistor R6 and the other end of the second capacitor C2 are grounded. The output end of the first hysteresis comparator U1.1 is connected to one end of the fourth resistor R4, the other end of the fourth resistor R4, the cathode of the first diode D1 and one end of the first resistor R1 are connected to the first node A, the anode of the first diode D1 is connected to the other end of the seventh resistor R7, and the other end of the first resistor R1 is connected to the +12V power supply. The first hysteresis comparator U1.1 is powered by dual power supplies, namely +12V power supply and -12V power supply.

[0084] The voltage of the reference voltage signal is 3V, which provides a reference voltage for the first hysteresis comparator U1.1. The third resistor R3, the fifth resistor R5, the sixth resistor R6 and the second capacitor C2 are used to set the first current threshold I_P1. The seventh resistor R7 is used to set the instantaneous current trigger recovery threshold I_P2. The dual threshold setting can prevent critical point jitter.

[0085] Among them, the first current threshold I_P1 and the instantaneous current trigger recovery threshold I_P2 can be set as needed, for example: the first current threshold I_P1 is 50A, and the instantaneous current trigger recovery threshold I_P2 is less than the first current threshold I_P1, or, the instantaneous current trigger recovery threshold I_P2 is 70A, and the instantaneous current trigger recovery threshold I_P2 is less than the first current threshold I_P1.

[0086] See also Figure 6 , Figure 6 is a schematic diagram of a circuit structure of an isolation unit, a steady-state current generating unit and a second comparing unit provided in an embodiment of the present application, such as Figure 6As shown, the isolation unit 206 includes a voltage follower U2.1 and an eighth resistor R8, wherein the output signal I_I N of the absolute value circuit (not shown in the figure) acts on the in-phase input terminal of the voltage follower U2.1, the inverting input terminal of the voltage follower U2.1 is respectively connected to one end of the eighth resistor R8 and the second comparison unit 202, and the output terminal of the voltage follower U2.1 is connected to the other end of the eighth resistor R8. The voltage follower U2.1 is powered by dual power supplies, namely a +12V power supply and a -12V power supply.

[0087] The voltage follower U2.1 isolates the output signal I_I N from the second comparison unit 202, thereby eliminating the mutual influence between the output signal I_I N and the second comparison unit 202, and can protect the internal circuit of the second comparison unit 202 from being affected by the high voltage.

[0088] The steady-state current generating unit 204 includes a tenth resistor R10 and a third capacitor C3, and the second comparing unit 202 includes a ninth resistor R9, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a fourth capacitor C4, a second hysteresis comparator U1.2 and a second diode D2.

[0089] One end of the tenth resistor R10 is connected to the output signal I_IN of the absolute value circuit, the other end of the tenth resistor R10 is respectively connected to one end of the third capacitor C3 and the inverting input end of the second hysteresis comparator U1.2, and the other end of the third capacitor C3 is grounded.

[0090] One end of the eleventh resistor R11 is connected to the reference voltage signal, and the other end of the eleventh resistor R11 is respectively connected to one end of the thirteenth resistor R13, one end of the fourteenth resistor R14, one end of the fourth capacitor C4, one end of the fifteenth resistor R15 and the in-phase input end of the second hysteresis comparator U1.2, and the other end of the thirteenth resistor R13, the other end of the fourteenth resistor R14 and the other end of the fourth capacitor C4 are grounded in common. The output end of the second hysteresis comparator U1.2 is connected to one end of the twelfth resistor R12, the other end of the twelfth resistor R12, the cathode of the second diode D2 and one end of the ninth resistor R9 are commonly connected to the second node B, the anode of the second diode D2 is connected to the other end of the fifteenth resistor R15, and the other end of the ninth resistor R9 is connected to the +12V power supply. The second hysteresis comparator U1.2 is powered by dual power supplies, namely +12V power supply and -12V power supply.

[0091] The tenth resistor R10 and the third capacitor C3 filter the output signal of the voltage follower U2.1 to obtain a steady-state current signal, and the steady-state current signal acts on the inverting input terminal of the second hysteresis comparator U1.2.

[0092] The voltage of the reference voltage signal is 3V, which provides a reference voltage for the second hysteresis comparator U1.2. The eleventh resistor R11, the thirteenth resistor R13, the fourteenth resistor R14 and the fourth capacitor C4 are used to set the second current threshold I_AVG1. The fifteenth resistor R15 is used to set the steady-state current trigger recovery threshold I_AVG2. The dual threshold setting can prevent critical point jitter.

[0093] The second current threshold I_AVG1 and the steady-state current trigger recovery threshold I_AVG2 can be set as needed. For example, the second current threshold I_AVG1 is 7A, and the steady-state current trigger recovery threshold I_AVG2 is less than the second current threshold I_AVG1.

[0094] At the same time, the first current threshold I_P1 is greater than the second current threshold I_AVG1. Since the steady-state current is the effective value of the sampling current and has a slow response speed, setting the second current threshold I_AVG1 smaller can enable a quick response when the steady-state current is small, thereby ensuring the current carrying capacity.

[0095] The first node A is the output terminal of the first hysteresis comparator U1.1, and the second node B is the output terminal of the second hysteresis comparator U1.2. The output signal I_I N is input to the inverting input terminal of the first hysteresis comparator U1.1, and compared with the first current threshold I_P1, the voltage value of the output signal I_I N represents the instantaneous current value. When the instantaneous current value is greater than the first current threshold I_P1, the output signal EN1 of the first hysteresis comparator U1.1 is low level, and when the instantaneous current value is less than or equal to the instantaneous current trigger recovery threshold I_P2, the output signal EN1 of the first hysteresis comparator U1.1 is high level.

[0096] Similarly, the output signal I_I N obtains a steady-state current through a filtering circuit composed of the tenth resistor R10 and the third capacitor C3. The steady-state current is input into the inverting input terminal of the second hysteresis comparator U1.2. When the steady-state current is greater than the second current threshold I_AVG1, the output signal EN2 of the second hysteresis comparator U1.2 is a low level. When the steady-state current is less than or equal to the steady-state current trigger recovery threshold I_AVG2, the output signal EN2 of the second hysteresis comparator U1.2 is a high level.

[0097] See also Figure 7 , Figure 7 is a schematic diagram of a circuit structure of a NAND gate and an AND gate provided in an embodiment of the present application, such as Figure 7As shown, the NAND gate 205 includes a third diode D3, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18 and a transistor Q1, the first cathode of the third diode D3 is connected to the signal EN1, the second cathode of the third diode D3 is connected to the signal EN2, the common anode of the third diode D3 is connected to one end of the seventeenth resistor R17, the other end of the seventeenth resistor R17 is respectively connected to one end of the sixteenth resistor R16 and the base of the transistor Q1, the other end of the sixteenth resistor R16 and the emitter of the transistor Q1 are commonly connected to a +5V power supply, the collector of the transistor Q1 is respectively connected to one end of the eighteenth resistor R18 and the second input end of the AND gate 502, the other end of the eighteenth resistor R18 is connected to the -12V power supply, and the first input end of the AND gate 502 is connected to the output end of the third comparison unit 501.

[0098] When either signal EN1 or signal EN2 is at a low level, NAND gate 205 outputs a first control signal through the collector of transistor Q1, which is a high level signal. When both signal EN1 and signal EN2 are at a high level, NAND gate 205 outputs a second control signal through the collector of transistor Q1, which is a low level signal.

[0099] The third comparison unit 501 is a comparator OCP (not shown in the figure), which is used to compare the sampled current with the overcurrent threshold. If the sampled current is greater than the overcurrent threshold, the comparator outputs a signal OCP_OFF, which is a low-level signal. The low-level signal OCP_OFF ​​drives the first group of switch tubes 1 to stop working. And the AND gate 502 outputs a signal DRI VE_ON, which is a low-level signal. The low-level signal DR IVE_ON drives the second group of switch tubes 2 to stop working.

[0100] If the sampling current is less than or equal to the overcurrent threshold, the comparator OCP outputs a high-level signal OCP_OFF. If the AND gate 502 receives the first control signal, the AND gate 502 outputs a high-level signal DRI VE_ON, so that the second group of switch tubes 2 work based on the received drive signal. If the AND gate 502 receives the second control signal, the AND gate 502 outputs a low-level signal DRIVE_ON, driving the second group of switch tubes 2 to stop working.

[0101] The overcurrent threshold can be set as needed, for example: the overcurrent threshold is 200A, and the overcurrent threshold is greater than the first current threshold, and the first current threshold is greater than the second current threshold.

[0102] Therefore, if overcurrent does not occur, and the instantaneous current is greater than the first current threshold, the first hysteresis comparator U1.1 outputs a low-level signal EN1, and the NAND gate 205 outputs a first control signal, which is a high-level signal, and the AND gate 502 outputs a high-level signal DRI VE_ON, so that the second group of switch tubes 2 work based on the received drive signal to ensure the current carrying capacity of the switching power supply. If overcurrent does not occur, and the steady-state current is greater than the second current threshold, the second hysteresis comparator U1.2 outputs a low-level signal EN2, and the NAND gate 205 outputs a first control signal, which is a high-level signal, and the AND gate 502 outputs a high-level signal DRIVE_ON, so that the second group of switch tubes 2 work based on the received drive signal to ensure the current carrying capacity of the switching power supply.

[0103] If no overcurrent occurs, when the instantaneous current is less than the instantaneous current trigger recovery threshold, and when the steady-state current is less than the steady-state current trigger recovery threshold, the output signal EN1 of the first hysteresis comparator U1.1 is high, and the output signal EN2 of the second hysteresis comparator U1.2 is high.

[0104] When the signals EN1 and EN2 are both high, the NAND gate 205 outputs the second control signal, which is a low signal, and the AND gate 502 outputs a low signal DRIVE_ON, so that the second set of switch tubes 2 stops working, achieving light load blocking and reducing switching losses.

[0105] In summary, the drive control circuit can not only effectively reduce the switching loss under light load and improve the light load energy efficiency, but also enable the switching power supply to quickly exit the light load blocking state when a sudden load or short circuit fault occurs and other high current conditions, thereby quickly improving the current carrying capacity of the switching power supply and ensuring the overload capacity of the switching power supply.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A drive control circuit, characterized in that: Applied to a switching power supply, the switching power supply comprises a first group of switching tubes and a second group of switching tubes, wherein the first group of switching tubes operates based on a received first driving signal, and the driving control circuit comprises: a current sampling circuit and a light-load wave-enclosing circuit, wherein the current sampling circuit is electrically connected to the light-load wave-enclosing circuit; The current sampling circuit is used to sample the current flowing through the load to obtain the sampled current; The light-load wave-capping circuit is used to output a first control signal in response to the result that the sampled current is greater than the current threshold, so as to make the second group of switch tubes work based on the received second drive signal; And in response to the result that the sampling current is less than or equal to the current threshold, a second control signal is output to drive the second group of switch tubes to stop working.

2. The drive control circuit according to claim 1, characterized in that: The sampled current includes an instantaneous current and a steady-state current, and the current threshold includes a first current threshold and a second current threshold; The light-load wave-capping circuit is used to respond to the result that the instantaneous current is less than or equal to the first current threshold and the steady-state current is less than or equal to the second current threshold, output the second control signal to drive the second group of switch tubes to stop working, otherwise, output the first control signal to make the second group of switch tubes work based on the received second drive signal.

3. The drive control circuit according to claim 2, characterized in that: The light load wave blocking circuit comprises: a first comparison unit, a second comparison unit and a NAND gate; The first comparison unit is electrically connected to the current sampling circuit and the first input terminal of the NAND gate respectively, the second comparison unit is electrically connected to the current sampling circuit and the second input terminal of the NAND gate respectively, and the output terminal of the NAND gate is used to output the first control signal or the second control signal; The first comparison unit is used to output a low-level first comparison signal in response to a result that the instantaneous current is greater than the first current threshold, and to output a high-level first comparison signal in response to a result that the instantaneous current is less than or equal to the first current threshold; The second comparison unit is used to output a low-level second comparison signal in response to a result that the steady-state current is greater than the second current threshold, and to output a high-level second comparison signal in response to a result that the steady-state current is less than or equal to the second current threshold; The NAND gate is used for responding to the input of the first comparison signal and the second comparison signal, and outputting the first control signal or the second control signal.

4. The drive control circuit according to claim 3, characterized in that: The light-load wave-sealing circuit further includes: a steady-state current generating unit; The steady-state current generating unit is electrically connected to the current sampling circuit and the second comparing unit respectively, and is used for generating and outputting the steady-state current in response to the input of the sampling current.

5. The drive control circuit according to any one of claims 1 to 4, characterized in that: The drive control circuit further includes: a chopper circuit; The chopper circuit is electrically connected to the current sampling circuit, the first group of switch tubes and the second group of switch tubes respectively. The chopper circuit is used to respond to the result that the sampling current is greater than the overcurrent threshold, output a first stop signal to drive the first group of switch tubes to stop working, and output a second stop signal to drive the second group of switch tubes to stop working.

6. The drive control circuit according to claim 5, characterized in that: The chopping circuit includes a third comparison unit and an AND gate; The third comparison unit is electrically connected to the current sampling circuit and the first input terminal of the AND gate respectively, and the second input terminal of the AND gate is used to receive the first control signal or the second control signal; The third comparison unit is used to respond to the result that the sampling current is greater than the overcurrent threshold value, and output the first stop signal to drive the first group of switch tubes to stop working. The AND gate is used to respond to the input of the first stop signal, and output the second stop signal to drive the second group of switch tubes to stop working.

7. The drive control circuit according to any one of claims 1 to 4, characterized in that: The drive control circuit further includes: a first controller and a second controller; The first controller is used to output the first drive signal. When the enable end of the second controller is connected to the first control signal, the output end of the second controller outputs the second drive signal. When the enable end of the second controller is connected to the second control signal, the second controller drives the second group of switch tubes to stop working.

8. The drive control circuit according to any one of claims 1 to 4, characterized in that: The current sampling circuit comprises: a sampling unit and a conversion unit; The sampling unit is electrically connected to the conversion unit, which is electrically connected to the light-load wave-enclosing circuit. The sampling unit is used to sample the current flowing through the load, and the conversion unit is used to convert the current flowing through the load into a positive current to obtain and output the sampled current.

9. The drive control circuit according to claim 3, characterized in that: The first current threshold is greater than the second current threshold.

10. A switching power supply, characterized in that: It includes a first group of switch tubes, a second group of switch tubes and a drive control circuit as described in any one of claims 1 to 9, wherein the first group of switch tubes operates based on the first drive signal received, and the drive control circuit is used to output the first control signal to make the second group of switch tubes operate based on the second drive signal received, and is used to output the second control signal to drive the second group of switch tubes to stop working.

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