A control method of a switching power supply device and a switching power supply device

Abstract

The application provides a control method of a switching power supply device and the switching power supply device. The control method comprises the following steps: monitoring the power supply state of the switching power supply device; and when it is monitored that the power supply state of the switching power supply device is converted from power-off to power-on, adjusting the on time of the switching power supply device from the maximum on time to the minimum on time. The switching power supply device reduces the output current by shortening the on time, so as to avoid the overshoot of the output current due to the large on time which exceeds the on time required for maintaining the set constant current output value, and affect the service life of the LED lamp.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and specifically to a control method for a switching power supply device and a switching power supply device. Background Technology

[0002] LED lights have seen rapid development in the lighting industry due to their advantages such as low energy consumption, long lifespan, and low pollution. However, with the widespread adoption of LED light sources, LED switching power supplies frequently experience power outages. For buck-type LED switching power supplies, after a drop in bus voltage, the large output electrolytic capacitor causes a slow decrease in output voltage, and the input voltage is also clamped near the output voltage. At this time, the controller continues to operate, and the system increases the conduction time to maintain a constant output current. If power is restored at this point, the long conduction time will cause the output current to exceed the set value. The system will then adjust to restore the set value. This results in an overshoot in the output current, meaning it exceeds the set value for a period of time. However, this current overshoot can negatively impact the lifespan of LED lights. Summary of the Invention

[0003] Based on this, the technical problem to be solved by the present invention is to overcome the defect of current overshoot after power failure and restart in the prior art, thereby providing a switching power supply control method and a switching power supply device.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] In a first aspect, embodiments of the present invention provide a control method for a switching power supply device, comprising: monitoring the power supply status of the switching power supply device; when the power supply status of the switching power supply device is detected to change from power-off to power-on, controlling the switching power supply device to start, and adjusting the conduction time of the switching power supply device from a first time to a second time, wherein the first time is the conduction time of the switching power supply device when the power supply status is power-off, and the first time is greater than the second time.

[0006] Optionally, monitoring the power supply status of the switching power supply device includes: monitoring a first voltage of a sampling resistor in the switching power supply device; and determining the power supply status of the switching power supply device based on the relationship between the first voltage and a first preset voltage threshold.

[0007] Optionally, before monitoring the first voltage of the sampling resistor in the switching power supply device, the control method of the switching power supply device further includes: monitoring the supply voltage of the switching power supply device; determining whether the time during which the supply voltage of the switching power supply device is greater than or equal to a second preset voltage threshold exceeds a first preset time period; and when the time during which the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold exceeds the first preset time period, performing the step of monitoring the first voltage of the sampling resistor in the switching power supply device.

[0008] Optionally, determining the power supply status of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold includes: determining whether the time during which the first voltage is less than the first preset voltage threshold exceeds a second preset time period; when the time during which the first voltage is less than the first preset voltage threshold exceeds the second preset time period, determining that the power supply status of the switching power supply device is power-off; when the time during which the first voltage is less than the first preset voltage threshold does not exceed the second preset time period, or when the first voltage is greater than or equal to the first preset voltage, determining that the power supply status of the switching power supply device is power-on.

[0009] Optionally, determining the power supply state of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold includes: when the first voltage is detected to change from being greater than or equal to the first preset voltage threshold to being less than the third preset voltage threshold, determining that the power supply state of the switching power supply device is power off, wherein the first preset voltage threshold is greater than the third preset voltage threshold.

[0010] Optionally, the step of determining the power supply status of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold further includes: after determining that the power supply status of the switching power supply device is power-off, when the duration of the first voltage being greater than the first preset voltage threshold is greater than a third preset time period, determining that the power supply status of the switching power supply device changes from power-off to power-on.

[0011] Optionally, the control method for the switching power supply device further includes: when the power supply state of the switching power supply device is detected to change from power-on to power-off, controlling the switching power supply device to shut down, and adjusting the conduction time of the switching power supply device from the second time to the first time.

[0012] Secondly, embodiments of the present invention provide a control device for a switching power supply device, comprising: a monitoring module for monitoring the power supply status of the switching power supply device; and a processing module for controlling the switching power supply device to start when the power supply status of the switching power supply device is detected to change from power-off to power-on, and adjusting the conduction time of the switching power supply device from a first time to a second time, wherein the first time is the conduction time of the switching power supply device when the power supply status is power-off, and the first time is greater than the second time.

[0013] Thirdly, embodiments of the present invention provide a switching power supply device, comprising: a controller, a sampling circuit, and a voltage regulating circuit, wherein a first terminal of the controller is connected to an external power supply, a second terminal of the controller is connected to an external load through the voltage regulating circuit, a third terminal of the controller is connected to the first terminal of the sampling circuit, and the third terminal of the controller is grounded; the second terminal of the sampling circuit is grounded; the controller is used to control the switching power supply device to start when it detects that the power supply state of the switching power supply device changes from power-off to power-on, and to adjust the conduction time of the voltage regulating circuit from a first time to a second time, wherein the first time is the conduction time of the voltage regulating circuit when the power supply state of the switching power supply device is power-off, and the first time is greater than the second time.

[0014] Optionally, the voltage regulating circuit includes: a first diode, a first capacitor, and a first inductor, wherein the anode of the first diode is connected to one end of the first inductor and the second end of the controller, the cathode of the first diode is connected to one end of the first capacitor and one end of the external load, and the other end of the first inductor is connected to the other end of the first capacitor and the other end of the external load.

[0015] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer instructions for causing the computer to execute the control method of the switching power supply device described in the first aspect of the present invention.

[0016] The technical solution of this invention has the following advantages:

[0017] The control method for a switching power supply device provided by this invention monitors the power supply status of the switching power supply device. When the power supply status changes from power-down to power-on, the on-time of the switching power supply device is adjusted from the maximum on-time to the minimum on-time. By shortening the on-time, the switching power supply device reduces the output current. This avoids overshooting of the output current due to a large on-time exceeding the on-time required to maintain the set constant current output value, which could affect the lifespan of the LED lamp.

[0018] The present invention provides a switching power supply device, comprising: a controller, a sampling circuit, and a voltage regulation circuit. The controller determines whether the switching power supply device has undergone a hot start by monitoring the sampling voltage of the sampling circuit. When the power supply state of the switching power supply device changes from power-off to hot start, a step-down circuit is formed using the voltage regulation circuit and the controller. By adjusting the duty cycle of the step-down circuit from maximum to minimum, the output current is reduced. This avoids overshoot in the output current due to a large conduction time exceeding the conduction time required to maintain the set constant current output value, which could affect the lifespan of the LED lamp. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A flowchart illustrating a specific example of a control method for a switching power supply device in an embodiment of the present invention;

[0021] Figure 2 This is a circuit diagram of a switching power supply device in an embodiment of the present invention;

[0022] Figure 3 This is a timing diagram of the control method of the switching power supply device in an embodiment of the present invention;

[0023] Figure 4 This is a schematic block diagram of a specific example of the control device of the switching power supply device in an embodiment of the present invention;

[0024] Figure 5 This is another circuit diagram of the switching power supply device in an embodiment of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] This invention provides a control method for a switching power supply device, such as... Figure 1 As shown, it includes the following steps:

[0030] Step S1: Monitor the power supply status of the switching power supply device.

[0031] In one specific embodiment, for such Figure 2 The buck-structured LED switching power supply shown exhibits a slow output voltage drop after the bus voltage decreases due to the large output electrolytic capacitor. Furthermore, the input voltage is clamped near the output voltage. At this time, the controller remains operational. To maintain a constant output current, the power supply increases its on-time. If the power supply is powered on again during this period, the extended on-time can cause the output current to exceed the set value. The system then adjusts to restore the output current to the set value. This current overshoot can negatively impact the LED's lifespan. Therefore, during a hot start, it is crucial to monitor the power supply status and implement appropriate measures to prevent output current overshoot that could affect the LED's lifespan.

[0032] Step S2: When the power supply status of the switching power supply device changes from power-off to power-on, control the switching power supply device to start, and adjust the conduction time of the switching power supply device from the first time to the second time. The first time is the conduction time when the power supply status of the switching power supply device is power-off, and the first time is greater than the second time.

[0033] In one specific embodiment, after a power outage, the switching power supply increases its on-time to the maximum on-time MaxON (i.e., the first time) to ensure a constant output current. Therefore, when the controller determines that the power supply status of the switching power supply has changed from power-down to power-on based on the power supply status, the controller reduces the on-time of the switching power supply to avoid output current overshoot. In this embodiment, after the switching power supply is powered on again, the on-time is adjusted from the first time to a second time. In this embodiment, the first time is the maximum on-time MaxON, and the second time is the minimum on-time MinON. By adjusting the on-time from the maximum on-time MaxON to the minimum on-time MinON, the switching power supply shortens the on-time and reduces the output current. This avoids output current overshoot caused by a large on-time exceeding the on-time required to maintain the set constant current output value.

[0034] In this embodiment of the invention, the maximum on-time MaxON is greater than the minimum on-time MinON. The maximum on-time MaxON and the minimum on-time MinON are determined based on actual operating conditions and are not limited here. In this embodiment of the invention, using... Figure 2 The following explanation uses an LED switching power supply device with a buck structure as an example. The controller integrates a first controllable switch. The first controllable switch S1, the first diode D1, the first capacitor C2, and the first inductor L1 constitute a buck circuit. The switching power supply device adjusts the duty cycle (on-time) of the first controllable switch S1 in the buck circuit to achieve voltage reduction control of the output current, thus avoiding output current overshoot.

[0035] The control method for a switching power supply device provided by this invention monitors the power supply status of the switching power supply device. When the power supply status changes from power-down to power-on, the on-time of the switching power supply device is adjusted from the maximum on-time to the minimum on-time. By shortening the on-time, the switching power supply device reduces the output current. This avoids overshooting of the output current due to a large on-time exceeding the on-time required to maintain the set constant current output value, which could affect the lifespan of the LED lamp.

[0036] In one embodiment, step S1 specifically includes the following steps:

[0037] Step S11: Monitor the power supply voltage of the switching power supply device.

[0038] Step S12: Determine whether the time during which the power supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold exceeds the first preset time period.

[0039] Step S13: When the time when the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold exceeds the first preset time period, monitor the first voltage of the sampling resistor in the switching power supply device.

[0040] Step S14: Determine the power supply status of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold.

[0041] In one specific embodiment, when monitoring the power supply status of the switching power supply device, it is first necessary to determine whether the switching power supply device has successfully cold-started based on its power supply voltage. In this embodiment of the invention, as... Figure 3 As shown, at time t1, when the supply voltage Vm of the switching power supply exceeds the second preset voltage threshold Vth, the controller in the switching power supply starts to power on. After the controller successfully powers on, the controller power indicator light displays VDD_OK. The switching power supply then adjusts the conduction time from the maximum conduction time MaxON to the minimum conduction time MinON.

[0042] The controller determines whether the time for which the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold exceeds the first preset time period Ltime1. At time t2, if the time for which the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold exceeds the first preset time period Ltime1, the switching power supply device performs a power-down detection. Specifically, the switching power supply device performs power-down detection based on the first voltage across the sampling resistor. When the time for which the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold does not exceed the first preset time period, step S1 is re-executed, and the controller is not detected as being in a power-down state. In this embodiment of the invention, a first preset time period is preset in the controller. By setting an appropriate hysteresis during power-down detection, i.e., delaying the first preset time period Ltime1, false judgments of power-down detection due to unstable supply voltage can be avoided, thereby improving the accuracy of power-down detection. In this embodiment of the invention, the second preset voltage threshold and the first preset time period can be adjusted according to actual needs, and are not limited here.

[0043] In one embodiment, step S14 specifically includes the following steps:

[0044] Step S1410: Determine whether the time during which the first voltage is less than the first preset voltage threshold exceeds the second preset time period.

[0045] Step S1411: When the time when the first voltage is less than the first preset voltage threshold exceeds the second preset time period, determine that the power supply state of the switching power supply device is power off.

[0046] Step S1412: When the time when the first voltage is less than the first preset voltage threshold does not exceed the second preset time period, or when the first voltage is greater than or equal to the first preset voltage, determine that the power supply state of the switching power supply device is powered on.

[0047] Step S1413: After determining that the power supply state of the switching power supply device is power off, when the duration of the first voltage being greater than the first preset voltage threshold is greater than the third preset time period, it is determined that the power supply state of the switching power supply device changes from power off to power on.

[0048] In one specific embodiment, power-down state detection begins when the supply voltage of the switching power supply device is greater than or equal to a second preset voltage threshold for a period exceeding a first preset time period, i.e., the time interval from time t2 to time t1 is greater than Ltime1. The specific detection scheme involves detecting the first voltage Vcs. Because during power-down, the supply voltage Vm gradually decreases, and the peak current also gradually decreases. When the supply voltage Vm approaches the output voltage Vo, the peak current is very small, even essentially zero. At this time, the first voltage Vcs across the corresponding sampling resistor Rcs is also essentially zero. Therefore, by detecting Vcs... CS Voltage is used to determine whether the switching power supply is in a power-off state. If the first voltage is less than a first preset voltage threshold for a period exceeding a second preset time period, the power supply state of the switching power supply is determined to be power-off. If the first voltage is less than the first preset voltage threshold for a period not exceeding the second preset time period, or if the first voltage is greater than or equal to the first preset voltage, the power supply state of the switching power supply is determined to always be power-on.

[0049] Furthermore, when the power supply state of the switching power supply device is power-off, the input voltage is increased, and the supply voltage Vm of the switching power supply device also gradually increases. At the same time, the first voltage Vcs across the sampling resistor Rcs also gradually increases. When the first voltage Vcs across the sampling resistor Rcs exceeds the first preset voltage threshold V1, the input voltage is considered to be high enough, and the switching power supply device enters normal operation and leaves the power-off state.

[0050] Furthermore, to prevent the switching power supply from malfunctioning due to input voltage fluctuations, additional limiting conditions can be added. For example, if the first voltage Vcs across the sampling resistor Rcs exceeds the first preset voltage threshold V1 for three consecutive preset time periods, the supply voltage is considered sufficiently high. The controller generates a start signal, triggering the switching power supply to start. After the switching power supply starts, the clock restarts. The conduction time changes from MaxON to the minimum conduction time MinON, and is adjusted according to the power-down state of the switching power supply. This avoids overshooting of the output current during hot starts, where the conduction time is too long, exceeding the time required to maintain the set constant current output value. In this embodiment of the invention, the third preset time period is generally 3 to 5 half-power frequency cycles.

[0051] In an optional embodiment, step S14 may further include the following steps:

[0052] Step S1420: When the first voltage is detected to change from being greater than or equal to the first preset voltage threshold to being less than the third preset voltage threshold, the power supply state of the switching power supply device is determined to be power off, and the first preset voltage threshold is greater than the third preset voltage threshold.

[0053] Step S1421: After determining that the power supply state of the switching power supply device is power off, when the duration of the first voltage being greater than or equal to the first preset voltage threshold is greater than the third preset time period, it is determined that the power supply state of the switching power supply device changes from power off to power on.

[0054] In one specific embodiment, power-down state detection is enabled when the supply voltage of the switching power supply device is greater than or equal to a second preset voltage threshold for a period exceeding a first preset time period Ltime1. The specific detection scheme involves detecting a first voltage Vcs. Because during power-down, the supply voltage Vm gradually decreases, and the peak current also gradually decreases. When the supply voltage Vm approaches the output voltage Vo, the peak current is very small, even essentially zero. At this time, the first voltage Vcs across the corresponding sampling resistor Rcs is also essentially zero. Therefore, by detecting Vcs... CS Voltage is used to determine whether the switching power supply is in a power-down state. In this embodiment of the invention, the area between a first preset voltage threshold and a third preset voltage threshold is set as an adjustment dead zone to appropriately reduce the judgment accuracy and avoid frequent switching of power-down states, which could affect the normal operation of the switching power supply. The first preset voltage threshold and the third preset voltage threshold can be adjusted according to actual needs, and are not limited here.

[0055] Furthermore, when the power supply state of the switching power supply device is power-off, the input voltage is increased, and the supply voltage Vm of the switching power supply device also gradually increases. At the same time, the first voltage Vcs across the sampling resistor Rcs also gradually increases. When the first voltage Vcs across the sampling resistor Rcs exceeds the first preset voltage threshold, the input voltage is considered to be high enough, and the switching power supply device enters normal operation and leaves the power-off state.

[0056] Furthermore, to prevent the switching power supply from erroneously starting due to input voltage fluctuations, additional limiting conditions can be added. For example, if the first voltage Vcs across the sampling resistor Rcs exceeds a first preset voltage threshold for three consecutive preset time periods, the supply voltage is considered sufficiently high. The controller generates a start signal, triggering the switching power supply to start. After the switching power supply starts, the clock restarts. The conduction time changes from MaxON to the minimum conduction time MinON, and is adjusted by the switching power supply according to its power-down state. This avoids overshooting of the output current during hot starts, where the conduction time is too long, exceeding the time required to maintain the set constant current output value. In this embodiment, the third preset time period is typically 3 to 5 half-power frequency cycles.

[0057] In one embodiment, the control method for the switching power supply device further includes:

[0058] Step S3: When the power supply status of the switching power supply device changes from power-on to power-off, control the switching power supply device to shut down, and adjust the conduction time of the switching power supply device from the second time to the first time.

[0059] In one specific embodiment, when the power supply state of the switching power supply device is detected to change from power-on to power-off, the supply voltage Vm gradually decreases, and the first voltage Vcs across the sampling resistor Rcs gradually decreases. For example... Figure 3As shown, at time t3, when the first voltage Vcs across the sampling resistor Rcs is lower than the third preset voltage threshold V1, the switching power supply starts timing. At time t4, after the timing exceeds the third preset time period (half a power frequency cycle), the switching power supply generates a power-down signal, and the system enters a power-down state. Simultaneously, the power-down flag Flag-PD changes from 0 to 1, indicating that the controller is powered down. During the power-down state, the controller adjusts the switching power supply's on-time to the maximum on-time MaxON. By adjusting the switching power supply's on-time to the maximum on-time MaxON during the power-down state, the controller can temporarily maintain a constant output current, delaying the power-down shutdown time of the switching power supply. Starting at time t5, the supply voltage Vm of the switching power supply gradually increases. Simultaneously, the first voltage Vcs across the sampling resistor Rcs also gradually increases. When at time t6, the first voltage Vcs across the sampling resistor Rcs exceeds the first preset voltage threshold, the input voltage is considered sufficiently high, and the switching power supply enters normal operation, exiting the power-down state. That is, at time t6, the on-time of the switching power supply device is adjusted from the maximum on-time MaxON to the minimum on-time MinON.

[0060] This invention provides a control device for a switching power supply, such as... Figure 4 As shown, it includes:

[0061] Monitoring module 1 is used to monitor the power supply status of the switching power supply device. For details, please refer to the relevant description of step S1 in the above embodiments, which will not be repeated here.

[0062] Processing module 2 is used to control the switching power supply device to start when the power supply state of the switching power supply device changes from power-off to power-on, and to adjust the conduction time of the switching power supply device from a first time to a second time. The first time is the conduction time of the switching power supply device when the power supply state is power-off, and the first time is greater than the second time. For details, please refer to the relevant description of step S2 in the above embodiment, which will not be repeated here.

[0063] This invention also provides a switching power supply device, such as... Figure 2 As shown, the system includes: a controller 1, a sampling circuit 2, and a voltage regulating circuit 3. The first terminal (HV) of the controller 1 is connected to an external power supply. The second terminal (DRAIN) of the controller 1 is connected to an external load via the voltage regulating circuit 3. The third terminal (CS) of the controller 1 is connected to the first terminal of the sampling circuit 2. The third terminal (GND) of the controller 1 is grounded. The second terminal of the sampling circuit 2 is grounded. The controller 1 is used to control the switching power supply to start when it detects that the power supply status of the switching power supply device has changed from power-off to power-on, and to adjust the conduction time of the voltage regulating circuit 3 from a first time to a second time. The first time is the conduction time of the voltage regulating circuit 3 when the power supply status of the switching power supply device is power-off, and the first time is greater than the second time.

[0064] In one specific embodiment, the voltage regulating circuit 3 includes: a first diode D1, a first capacitor C2, and a first inductor L1. The anode of the first diode D1 is connected to one end of the first inductor L1 and the second terminal DRAIN of the controller 1. The cathode of the first diode D1 is connected to one end of the first capacitor C2 and one end of an external load. The other end of the first inductor L1 is connected to the other end of the first capacitor C2 and the other end of the external load. The sampling circuit 2 includes a sampling resistor Rcs. The first end of the sampling resistor Rcs is connected to the third terminal CS of the controller 1. The second end of the sampling resistor Rcs is grounded.

[0065] In this embodiment of the invention, a first controllable switch S1 is provided within the controller 1. The connection relationship between the first controllable switch S1 and the voltage regulating circuit 3 is as follows: Figure 5 As shown. The first terminal of the first controllable switch S1 is connected to the anode of the first diode D1 and one end of the first inductor L1. The control terminal of the first controllable switch S1 is connected to the second terminal of the controller. The second terminal of the first controllable switch S1 is grounded. When the controller 1 detects that the power supply state of the switching power supply device has changed from power-off to power-on, it controls the switching power supply device to start and adjusts the conduction time of the first controllable switch S1 from a first time to a second time. The first time is the conduction time of the voltage regulation circuit 3 when the power supply state of the switching power supply device is power-off, and the first time is greater than the second time.

[0066] Specifically, when the supply voltage Vm of the switching power supply exceeds a certain value (e.g., 30V or 40V), the controller in the switching power supply begins to activate. Further, after the controller power indication signal VDD_OK is established, a protection time Ltime is set. During this time, the controller is not checked for power failure to prevent false triggering during startup.

[0067] When the supply voltage of the switching power supply device exceeds the second preset voltage threshold for a period exceeding the first preset time period Ltime, power-down state detection is enabled. The specific detection method involves detecting the first voltage Vcs. Because during power-down, the supply voltage Vm gradually decreases, and the peak current also gradually decreases. When the supply voltage Vm approaches the output voltage Vo, the peak current is very small, even essentially zero. At this time, the first voltage Vcs across the sampling resistor Rcs is also essentially zero. Therefore, detecting the VCS voltage can determine whether the switching power supply device is in a power-down state.

[0068] When the power supply status of the switching power supply device changes from power-on to power-off, the supply voltage Vm gradually decreases, and the first voltage Vcs across the sampling resistor Rcs gradually decreases. When the first voltage Vcs across the sampling resistor Rcs falls below a third preset voltage threshold, the switching power supply device starts timing. After the timing exceeds the third preset time period, the switching power supply device generates a power-off signal, and the system enters a power-off state. In the power-off state, the controller adjusts the switching power supply device's on-time to the maximum on-time MaxON. When the power supply status of the switching power supply device is power-off, the input voltage is increased, and the supply voltage Vm of the switching power supply device gradually increases. Simultaneously, the first voltage Vcs across the sampling resistor Rcs also gradually increases. When the first voltage Vcs across the sampling resistor Rcs exceeds the first preset voltage threshold, the input voltage is considered sufficiently high, and the switching power supply device enters normal operation, exiting the power-off state.

[0069] Furthermore, to prevent the switching power supply from erroneously starting due to input voltage fluctuations, additional limiting conditions can be added. For example, if the first voltage Vcs across the sampling resistor Rcs exceeds a first preset voltage threshold for three consecutive preset time periods, the supply voltage is considered sufficiently high. The controller generates a start signal, triggering the switching power supply to start. After the switching power supply starts, the clock restarts. The on-time changes from MaxON to the minimum on-time MinON, and is adjusted by the switching power supply based on its power-down state. This prevents overshoot in the output current during a warm start, where the on-time is too long, exceeding the time required to maintain the set constant current output value.

[0070] The present invention provides a switching power supply device, comprising: a controller, a sampling circuit, and a voltage regulation circuit. The controller determines whether the switching power supply device has undergone a hot start by monitoring the sampling voltage of the sampling circuit. When the power supply state of the switching power supply device changes from power-off to hot start, a step-down circuit is formed using the voltage regulation circuit and the controller. By adjusting the duty cycle of the step-down circuit from maximum to minimum, the output current is reduced. This avoids overshoot in the output current due to a large conduction time exceeding the conduction time required to maintain the set constant current output value, which could affect the lifespan of the LED lamp.

[0071] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A control method for a switching power supply device, characterized in that, include: Monitor the power supply status of the switching power supply device; When the power supply status of the switching power supply device is detected to change from power-off to power-on, the switching power supply device is controlled to start, and the conduction time of the switching power supply device is adjusted from a first time to a second time. The first time is the conduction time when the power supply status of the switching power supply device is power-off, and the first time is greater than the second time. When the power supply status of the switching power supply device is detected to change from power-on to power-off, the switching power supply device is controlled to shut down, and the conduction time of the switching power supply device is adjusted from the second time to the first time.

2. The control method for the switching power supply device according to claim 1, characterized in that, Monitoring the power supply status of the switching power supply device includes: Monitor the first voltage of the sampling resistor in the switching power supply device; The power supply status of the switching power supply device is determined based on the relationship between the first voltage and the first preset voltage threshold.

3. The method according to claim 2, characterized in that, Before monitoring the first voltage of the sampling resistor in the switching power supply device, the control method of the switching power supply device further includes: Monitor the power supply voltage of the switching power supply device; Determine whether the time during which the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold exceeds the first preset time period; When the supply voltage of the switching power supply device is greater than or equal to the second preset voltage threshold for a period of time exceeding the first preset time period, the step of monitoring the first voltage of the sampling resistor in the switching power supply device is executed.

4. The control method for the switching power supply device according to claim 2, characterized in that, The step of determining the power supply status of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold includes: Determine whether the time during which the first voltage is less than the first preset voltage threshold exceeds a second preset time period; When the time during which the first voltage is less than the first preset voltage threshold exceeds the second preset time period, the power supply state of the switching power supply device is determined to be power off. The power supply state of the switching power supply device is determined to be powered on when the time during which the first voltage is less than the first preset voltage threshold does not exceed the second preset time period, or when the first voltage is greater than or equal to the first preset voltage.

5. The control method for the switching power supply device according to claim 2, characterized in that, The step of determining the power supply status of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold includes: When the first voltage is detected to change from being greater than or equal to a first preset voltage threshold to being less than a third preset voltage threshold, the power supply state of the switching power supply device is determined to be power off, and the first preset voltage threshold is greater than the third preset voltage threshold.

6. The control method for the switching power supply device according to claim 4 or 5, characterized in that, The step of determining the power supply status of the switching power supply device based on the relationship between the first voltage and the first preset voltage threshold further includes: After determining that the power supply state of the switching power supply device is power-off, when the duration of the first voltage being greater than the first preset voltage threshold is greater than the third preset time period, it is determined that the power supply state of the switching power supply device changes from power-off to power-on.

7. A control device for a switching power supply, characterized in that, include: The monitoring module is used to monitor the power supply status of the switching power supply device; The processing module is used to control the switching power supply device to start when the power supply state of the switching power supply device is detected to change from power-off to power-on, and to adjust the conduction time of the switching power supply device from a first time to a second time. The first time is the conduction time when the power supply state of the switching power supply device is power-off, and the first time is greater than the second time. When the power supply status of the switching power supply device is detected to change from power-on to power-off, the switching power supply device is controlled to shut down, and the conduction time of the switching power supply device is adjusted from the second time to the first time.

8. A switching power supply device, characterized in that, include: The system comprises a controller (1), a sampling circuit (2), and a voltage regulation circuit (3), wherein, The first end of the controller (1) is connected to an external power supply, the second end of the controller (1) is connected to an external load through the voltage regulating circuit (3), the third end of the controller (1) is connected to the first end of the sampling circuit (2), and the third end of the controller (1) is grounded. The second terminal of the sampling circuit (2) is grounded; The controller (1) is used to control the switching power supply device to start when the power supply state of the switching power supply device changes from power-off to power-on, and to adjust the conduction time of the voltage regulating circuit (3) from a first time to a second time. The first time is the conduction time of the voltage regulating circuit (3) when the power supply state of the switching power supply device is power-off, and the first time is greater than the second time. When the power supply status of the switching power supply device is detected to change from power-on to power-off, the switching power supply device is controlled to shut down, and the conduction time of the switching power supply device is adjusted from the second time to the first time.

9. The switching power supply device according to claim 8, characterized in that, The voltage regulating circuit (3) includes: a first diode (D1), a first capacitor (C2), and a first inductor (L1), wherein, The anode of the first diode (D1) is connected to one end of the first inductor (L1) and the second end of the controller (1), and the cathode of the first diode (D1) is connected to one end of the first capacitor (C2) and one end of the external load, respectively. The other end of the first inductor (L1) is connected to the other end of the first capacitor (C2) and the other end of the external load, respectively.

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