Lighting circuit compatible with electronic ballast
By introducing a clamping circuit and a leakage protection module into the lighting circuit, the problem of unstable power supply caused by bus voltage oscillation is solved, stable power supply compatible with electronic ballasts and mains power is achieved, and the stability and safety of the system are improved.
Patent Information
- Application Number
- CN202422510601.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-10-16
AI Technical Summary
In existing lighting systems compatible with electronic ballasts and mains electricity, bus voltage oscillations lead to unstable power supply and the system is prone to multiple restarts.
A clamping circuit and a leakage protection module are introduced into the lighting circuit. The clamping circuit limits the bus voltage to a preset range to avoid oscillation. Combined with the leakage protection module, leakage detection is performed under mains power conditions to ensure stable power supply to the system.
It achieves stable power supply for the lighting system under the conditions of mains power and electronic ballast, avoids system restart, and improves system stability and safety.
Smart Images
Figure CN223334822U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power electronics, and in particular to a lighting circuit compatible with an electronic ballast. Background Art
[0002] With the widespread use of LED lights, the control requirements for LED lamps are becoming increasingly stringent. They need to be able to replace traditional fluorescent lamps to adapt to electronic ballast circuits and also need to be able to adapt to AC mains requirements. Therefore, the driving circuit of LED lamps needs to be compatible with both electronic ballasts (denoted as TYPEA) and AC mains (denoted as TYPEB), and can also ensure safety issues when using AC power, such as leakage protection.
[0003] Existing solutions that are compatible with electronic ballasts and AC power generally require two circuits to implement. One part of the circuit, such as the leakage detection circuit, is used to detect whether there is leakage. If there is no leakage, it transmits a valid enable signal to the subsequent LED driver circuit; the other part of the circuit is used to detect whether there is an electronic ballast at the input end. This part of the circuit is generally a separate TYPEA detection circuit and control switch. The separate detection circuit is usually composed of a capacitor and a bridge stack, which is used to detect whether there is an electronic ballast.
[0004] Figure 1 The schematic diagram of an existing lighting circuit compatible with electronic ballasts is shown, including a switching power circuit for driving a load. When the detection module detects that no electronic ballast is connected, the leakage protection module transmits the leakage detection result to the constant current controller to control the power tube Q1 of the switching power circuit, thereby controlling the brightness of the LED. When the detection module detects the presence of an electronic ballast, the detection result is transmitted to the constant current controller to control the power tube Q1 to be constantly turned on. The load brightness of the LED depends on the electronic ballast. Because the switching power circuit includes an inductor L1, the inductor L1 and the input capacitor Cin form a resonant circuit, causing the bus voltage Vbus to oscillate. When the bus voltage Vbus oscillates to a lower value, the system's power supply voltage will also oscillate to a lower value, resulting in the power supply voltage being insufficient to support system operation, which in turn causes the system to restart multiple times. Therefore, the existing lighting system is unstable and prone to multiple system restarts. Utility Model Content
[0005] The purpose of this application is to provide a lighting circuit compatible with electronic ballasts, which is used to solve the problems in the prior art such as bus voltage oscillation, system instability, unstable power supply, and multiple system restarts.
[0006] The present application proposes a lighting circuit compatible with an electronic ballast, comprising a rectifier circuit for rectifying an input signal to obtain a bus voltage, and further comprising:
[0007] A switching power circuit, connected to the output end of the rectifier circuit, for driving a load, comprising a main power tube and an inductor connected thereto;
[0008] A driving device detects an input signal and determines whether the input end of the lighting circuit is connected to the mains or the electronic ballast to control the working mode of the main power tube;
[0009] A clamping circuit is connected to the cathode of the load, and when the load is turned on, the sum of the voltage on the clamping circuit and the load voltage represents the bus voltage;
[0010] When it is determined that the input end of the lighting circuit is connected to the electronic ballast, the main power tube operates in a pass-through mode, and the voltage on the clamping circuit is clamped within a first preset range to clamp the bus voltage within a second preset range.
[0011] Optionally, when the input end of the lighting circuit is connected to the electronic ballast, if the bus voltage is less than or equal to a second preset voltage, the clamping circuit is turned on and the bus voltage is clamped at the first preset voltage.
[0012] Optionally, when the input end of the lighting circuit is connected to the electronic ballast, the clamping circuit is turned on and the bus voltage is clamped at a second preset voltage.
[0013] Optionally, a power supply device is further included, the input end of which is connected to a busbar and is used to draw power from the busbar to generate a power supply voltage, and the power supply voltage is used to power the lighting circuit;
[0014] When the input end of the lighting circuit is connected to the electronic ballast, the supply voltage is within a preset power supply range.
[0015] Optionally, the clamping circuit includes a diode, a cathode of the diode is connected to the cathode of the load, and an anode of the diode is grounded.
[0016] Optionally, the clamping circuit includes a switching tube, and when the discrimination signal indicates that the input end of the rectifier circuit is connected to the electronic ballast, the switching tube is constantly turned on.
[0017] Optionally, the driving device includes a detection module, a leakage protection module and a constant current controller, wherein the input end of the detection module is connected to one of the input ends of the rectifier circuit and outputs a discrimination signal, wherein the discrimination signal indicates whether the input end of the rectifier circuit is connected to the electronic ballast or the mains;
[0018] The input end of the leakage protection module is connected to one of the input ends or the output end of the rectifier circuit. When the discrimination signal indicates that the input end of the rectifier circuit is connected to the mains, the leakage protection module performs leakage detection and outputs an enable signal representing the leakage detection result.
[0019] The constant current controller receives the discrimination signal, the enable signal and a current feedback signal representing the load current, and generates a switch control signal to control the main power switch tube to operate in different modes.
[0020] Optionally, when the judgment signal indicates that the input end of the rectifier circuit is connected to the mains, the leakage protection module is enabled to work. When the leakage protection module detects that there is no leakage, it outputs an enable signal in a high-level valid state to the constant current controller, and when it detects that there is leakage, it outputs an enable signal in a low-level invalid state to the constant current controller.
[0021] Optionally, when the discrimination signal indicates that the input end of the rectifier circuit is connected to the mains,
[0022] When the enable signal output by the leakage protection module is in a low-level invalid state, the switch control signal controls the main power tube to operate in a shutdown mode;
[0023] When the enable signal of the leakage protection module is in a high-level active state, the switch control signal controls the main power tube to operate in a switch mode.
[0024] The detection module determines whether the input end of the rectifier circuit is connected to the mains or the electronic ballast according to the frequency of the input signal.
[0025] Compared with the existing technology, the present application has the following advantages: the lighting circuit of the present application is compatible with electronic ballasts, and when the input end of the lighting circuit is connected to the mains, a leakage protection module is set to perform leakage protection; when the input end of the lighting circuit is connected to the electronic ballast, a clamping circuit is added to the lighting circuit to limit the bus voltage oscillation, thereby avoiding the problem of too low power supply voltage causing system restart. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 A schematic diagram of a lighting circuit compatible with existing electronic ballasts;
[0027] Figure 2 A schematic diagram of an embodiment of a lighting circuit compatible with an electronic ballast for this application;
[0028] Figure 3 This is a schematic diagram of an embodiment of the leakage protection module of the present application;
[0029] Figure 4 This is a schematic diagram of an embodiment of the detection module of this application;
[0030] Figure 5 This is a schematic diagram of an embodiment of a constant current controller of this application. DETAILED DESCRIPTION
[0031] The preferred embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application is not limited to these embodiments. The present application covers any substitution, modification, equivalent method and solution made within the spirit and scope of the present application.
[0032] In order to enable the public to have a thorough understanding of the present application, specific details are described in detail in the following preferred embodiments of the present application, but those skilled in the art can fully understand the present application without the description of these details.
[0033] The present application is described in more detail in the following paragraphs with reference to the accompanying drawings. It should be noted that the drawings are simplified and not to exact proportions, in order to facilitate and clearly illustrate the purpose of the embodiments of the present application.
[0034] Reference Figure 2 , illustrates a schematic diagram of Example 1 of a lighting circuit compatible with an electronic ballast of the present application. The lighting circuit takes LED load lighting as an example. The lighting circuit includes a rectifier circuit, a diode D0, and a filter capacitor Cin. The rectifier circuit includes a rectifier bridge. The rectifier circuit receives an input signal and obtains a bus voltage Vbus after rectification. The lighting circuit of the present invention is compatible with an electronic ballast. Therefore, the input signal of the rectifier circuit is an AC input signal provided by the mains (denoted as TYPEB), that is, the two ends of the rectifier circuit are respectively connected to the live wire L and the neutral wire N of the mains. Alternatively, the input signal of the rectifier circuit is provided by an electronic ballast (denoted as TYPEA), that is, the electronic ballast is connected to the input end of the rectifier circuit. The diode D0 is connected in series to the bus at the output end of the rectifier circuit to prevent the reverse current generated by the back-end circuit from flowing into the rectifier circuit. The filter capacitor Cin is used to filter the bus voltage Vbus.
[0035] The lighting circuit also includes a switching power circuit, connected between the filter capacitor Cin and the load LED, for driving the load. The switching power circuit receives the filtered bus voltage Vbus and converts it to provide a driving voltage for the load. The switching power circuit includes a main power transistor Q1 and an inductor L1. Figure 2 In the illustrated example, the switching power circuit is a step-down circuit, with the rectifier tube being the upper tube and the main power tube Q1 being the lower tube. Specifically, the rectifier tube is a diode D1, the cathode of diode D1 being connected to the busbar, the anode of diode D1 being connected to the first end of the main power tube Q1, the second end of the main power tube Q1 being grounded via a sampling resistor, the first end of inductor L1 being connected to the common connection terminal of the main power tube Q1 and diode D1, the second end of inductor L1 being connected to output capacitor Co, and the LED load being connected in parallel with the output capacitor. Other types of switching power circuits can also be used for LED driving, but a step-down circuit with the main power tube on the low side is more convenient for controlling the LED constant current and is easier to implement.
[0036] Reference Figure 2 The lighting circuit also includes a driver for controlling the switching state of the main power transistor Q1 in the switching power circuit, including controlling the operating mode of the main power transistor Q1. Specifically, the driver includes a detection module, a leakage protection module, and a constant current controller. The detection module is used to detect whether the input of the lighting circuit is connected to the mains or an electronic ballast. Furthermore, since the AC signal of the mains is generally a low-frequency signal of 50Hz or 60Hz, and the output signal of the electronic ballast is generally a high-frequency signal of 25kHz to 125kHz, the detection module can determine whether the input of the lighting circuit is connected to the mains or the electronic ballast by detecting the frequency of the input signal. Furthermore, the input of the detection module is connected to any input of the rectifier circuit and outputs a discrimination signal EN2. For example, when the discrimination signal EN2 is active high, it indicates that the input of the lighting circuit is connected to the electronic ballast, controlling the main power transistor to be constantly on, and the brightness of the LED load is determined by the electronic ballast. When the discrimination signal EN2 is inactive low, it indicates that the input of the lighting circuit is connected to the mains. When the input end of the lighting circuit is connected to the mains, in order to prevent leakage from causing harm to the human body, the leakage protection module detects whether there is leakage in the lighting circuit loop to obtain an enable signal indicating whether there is leakage. For example, when the enable signal is valid at a high level, it indicates that there is no leakage in the lighting circuit loop, and the main power tube Q1 is controlled to perform normal switching action to drive the LED load. When the enable signal is invalid at a low level, it indicates that there is leakage in the lighting circuit loop, and the main power tube Q1 is turned off to prevent the human body from being electrocuted. Furthermore, the input end of the leakage protection module can be connected to any input end of the rectifier circuit or the output end of the rectifier circuit, that is, the leakage protection module can determine whether there is leakage in the lighting circuit by detecting the AC input signal of the mains or the bus voltage signal obtained after rectification. The constant current controller receives the judgment signal EN2, the enable signal EN1 and the current feedback signal VS, and outputs a switch control signal to control the switching state of the main power tube Q1; specifically, when the judgment signal EN2 is valid, indicating that the electronic ballast is connected to the lighting circuit, the enable signal EN1 has no effect / is invalid on the constant current controller, and the switch control signal controls the main power tube Q1 to be constantly turned on, and the LED brightness is determined by the electronic ballast; when the judgment signal EN2 is invalid, indicating that the AC power is connected to the lighting circuit, if the enable signal EN1 is valid, the constant current controller generates a switch control signal according to the current feedback signal VS to control the main power tube to operate in the switching mode, that is, the main power tube performs normal switching action. If the enable signal EN1 is invalid, the switch control signal controls the main power tube Q1 to be turned off.
[0037] Since the switching power circuit includes the inductor L1, when the lighting circuit is connected to the electronic ballast, the main power tube Q1 is constantly turned on, which will cause the inductor L1 and the input capacitor Cin to form a resonant path. Therefore, the lighting circuit of the present invention is also provided with a clamping circuit, such as Figure 2In the buck circuit shown, the clamp circuit is connected between the cathode of the LED load and the ground terminal, and the load voltage, that is, the sum of the voltage of the output capacitor C0 and the voltage across the clamp circuit, is equal to the bus voltage Vbus. Figure 2 In the embodiment, the clamping circuit is preferably a diode D2, the cathode of which is connected to the cathode of the LED, and the anode of which is grounded. When the main power transistor Q1 is turned on, if the bus voltage Vbus oscillates to a low value, the cathode voltage of diode D2 also oscillates to a low negative voltage value, causing diode D2 to turn on. The diode clamps the voltage between the LED cathode and ground to a negative voltage value of -VD (VD is the voltage drop of diode D2). The bus voltage Vbus is also clamped to VC0 + (-VD), preventing the bus voltage Vbus from oscillating too low and causing multiple system restarts. In another embodiment, the clamping circuit can also be a switch. When the main power transistor Q1 is constantly turned on, the switch of the clamping circuit is controlled to be constantly turned on to clamp the cathode voltage of the LED to the drain voltage of the switch. When the switch is fully turned on, the drain voltage is zero voltage. The utility model provides a clamping circuit. When the main power tube operates in the pass-through mode (constant conduction), the LED cathode voltage / the voltage of the clamping circuit is clamped within a certain preset range, so that the bus voltage Vbus is also clamped within the corresponding preset range, thereby preventing the bus voltage Vbus from oscillating to a lower value and stabilizing the response system.
[0038] Reference Figure 2 The lighting circuit also includes a power supply module, including a JFET (junction field-effect transistor) and a power supply unit. One end of the JFET receives the bus voltage Vbus, and the other end is connected to the power supply unit. The JFET gate is grounded. When the JFET is turned on, it generates a certain current to charge the capacitor in the power supply unit to generate the power supply voltage VDD. The power supply voltage VDD powers the entire lighting system. Because the JFET draws power from the bus voltage Vbus, if the bus voltage Vbus oscillates to a low value, the power supply voltage VDD will also oscillate to a low value, causing the entire lighting system to lose power and become inoperable. When the bus voltage Vbus oscillates to a higher value, the power supply voltage VDD will also oscillate to a higher value, causing the lighting system to restart. This cycle repeats, making it difficult for the power supply device to provide a stable power supply voltage VDD, which in turn makes it difficult for the entire system to operate stably. The present invention provides a clamping circuit to clamp the bus voltage Vbus within a certain range when the main power tube Q1 is turned on, thereby clamping the power supply voltage VDD within a corresponding certain voltage range, so as to provide a stable power supply voltage for the lighting system, avoid the lighting system from being powered off due to the power supply voltage VDD being too low, and thus improve the stability of the lighting system.
[0039] like Figure 3As shown, a schematic diagram of an embodiment of a leakage protection module is shown, which includes a leakage detection path and a comparison circuit. The leakage detection path includes a detection circuit (such as resistors R1 and R2) and a detection switch tube (such as M1) connected in series. The detection switch tube is controlled to be on and off according to an intermittent pulse signal. The intermittent pulse signal can be obtained by comparing the detection voltage signal representing the bus voltage Vbus (such as obtained by voltage division sampling by voltage divider resistors R3 and R4) and the reference signal Vref1 by the comparator comp1, or it can be provided by a set pulse signal generator; the comparison circuit compares the node voltage on the detection path with the reference voltage to determine whether there is leakage at the input end, and generates the enable signal according to the comparison result. Here, when switch M1 is turned on, a detection current or voltage signal representing the input voltage or current is obtained on the detection path. For example, comparator comp2 compares the voltage at the node between switch M1 and resistor R2 with a reference voltage Vref2. If the node voltage is less than the reference voltage Vref2, it indicates leakage at the input (i.e., a human body is connected). In this case, the enable signal EN1 output by the logic circuit is in an inactive low state. If the node voltage is greater than the reference voltage Vref2, it indicates no leakage at the input (i.e., no human body is connected). In this case, the enable signal EN1 output by the logic circuit is in an active high state. This leakage detection circuit can effectively detect leakage at the input, ensuring user safety when using mains power.
[0040] like Figure 4 As shown, a schematic diagram of an embodiment of a detection module is illustrated. The detection module includes a first capacitor C1, a second capacitor C2 and a comparison circuit comp3. One end of the first capacitor is connected to an input end, such as one of the input ends of a rectifier circuit, and the other end charges the second capacitor through a rectifier diode D3. The comparison circuit compares the voltage amplitude of the second capacitor with the reference zero voltage. When the AC power is input, since the frequency of the AC power is 50 or 60 Hz, the voltage across the second capacitor C2 will not be established due to the low-frequency blocking effect of the first capacitor C1. The voltage amplitude of the second capacitor C2 is zero, and the comparison voltage outputs a comparison signal of a low-level invalid state (such as EN2); when the electronic ballast is input, since its frequency is 25KHz to 125KHz, the first capacitor C1 is in a high-frequency and low-impedance state, and the current flowing through the first capacitor C1 begins to charge the second capacitor C2. The voltage amplitude of the second capacitor is greater than zero, and the comparison voltage outputs a comparison signal of a high-level valid state. As shown Figure 4The detection module includes a discharge circuit (such as resistor R5) and a clamping circuit (such as clamping tube Z1). The discharge circuit and the clamping circuit are connected in parallel at both ends of the second capacitor C2. The clamping circuit is used to clamp the voltage across the second capacitor C2. When the second capacitor C2 is charged to the clamping voltage, it is clamped at the clamping voltage. After that, the voltage of the second capacitor is the regulated value of Z1, and the constant current controller controls the main power switch tube Q2 to enter the pass-through mode. In this way, the input signal is identified according to the different frequencies of the input signal. Figure 4 The embodiment in the figure is only one way of frequency identification. There are other identification methods. In view of the large difference between the frequencies of the two input signals, a frequency comparison can be directly set to see whether the frequency threshold is reached to distinguish the difference between the input signals. Figure 4 The diode D2 in the circuit serves as a discharge circuit for the first capacitor C1 to better protect the components of the circuit and prevent the circuit from being damaged.
[0041] like Figure 5 The figure shows a schematic diagram of an embodiment of a constant current controller, including a constant current control unit and a logic control circuit. The constant current control unit receives a current feedback signal VS representing the load current and an enable signal EN1 output by the leakage protection module to generate a switch control signal to control the main power switch tube to operate in different modes. When the lighting circuit is connected to the mains power input, the state of the main power switch tube Q1 needs to be further determined based on the leakage detection result. When the leakage protection module detection result indicates that leakage exists, its enable signal EN1 is in a low-level inactive state, and the switch control signal controls the main power switch tube Q2 to operate in the off mode. When the leakage protection module detection result indicates that no leakage exists, the enable signal EN1 is in a high-level active state, and the constant current control unit generates a switch control signal based on the current feedback signal to control the main power switch tube Q2 to operate in the switching mode (i.e., constant current mode). Here, the judgment signal EN2 output by the frequency detection circuit and the output signal VC1 of the constant current control unit are subjected to logical operations by the logic control circuit 2, so that under different circumstances, the main power tube Q1 can operate according to the working mode of this application, thereby using a switching tube to realize a circuit compatible with AC power and electronic ballast, and to achieve leakage protection requirements under AC power conditions.
[0042] Furthermore, during the leakage protection module's leakage detection and the detection module's input signal identification and judgment, after receiving an external signal at the input, the leakage protection module begins detecting input leakage after its supply voltage reaches the cut-in voltage; and the detection module begins identifying input signals after its supply voltage reaches the cut-in voltage. These two modules can operate simultaneously or alternately, without waiting for the detection results of the other module. This significantly shortens detection time, and the operating state of the main power transistor Q1 can be controlled based on the detection results.
[0043] Furthermore, the leakage detection module needs to wait for the detection result of the detection module. For example, when the judgment signal EN2 is valid, indicating that the lighting circuit is connected to the electronic ballast, the leakage detection module can be controlled to be disabled to avoid the leakage detection module from performing invalid work and wasting resources; when the judgment signal EN2 is invalid, indicating that the lighting circuit is connected to the mains, the leakage detection module can be controlled to be enabled to perform leakage detection. When the lighting circuit leaks, leakage protection is performed in time. In this way, the leakage protection module can be avoided from performing unnecessary leakage detection and saving resources.
[0044] The utility model reuses the function of the main power tube Q1. Regardless of the mains input or the electronic ballast input, the LED load state can be controlled by controlling the switching state of the main power tube, thereby optimizing the use of power devices to the greatest extent without the need for additional switching devices.
[0045] Although the embodiments are described and explained separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that they can be replaced and integrated between the embodiments. If there is anything not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.
[0046] The above-described embodiments do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the above-described embodiments shall be included in the scope of protection of this technical solution.
Claims
1. A lighting circuit compatible with an electronic ballast, comprising a rectifier circuit for rectifying an input signal to obtain a bus voltage, characterized in that: Also includes, A switching power circuit, connected to the output end of the rectifier circuit, for driving a load, comprising a main power tube and an inductor connected thereto; A driving device detects an input signal and determines whether the input end of the lighting circuit is connected to the mains or the electronic ballast to control the working mode of the main power tube; A clamping circuit is connected to the cathode of the load, and when the load is turned on, the sum of the voltage on the clamping circuit and the load voltage represents the bus voltage; When it is determined that the input end of the lighting circuit is connected to the electronic ballast, the main power tube operates in a pass-through mode, and the voltage on the clamping circuit is clamped within a first preset range to clamp the bus voltage within a second preset range.
2. The lighting circuit according to claim 1, wherein: When the input end of the lighting circuit is connected to the electronic ballast, if the bus voltage is less than or equal to the second preset voltage, the clamping circuit is turned on and the bus voltage is clamped at the first preset voltage.
3. The lighting circuit according to claim 1, wherein: When the input end of the lighting circuit is connected to the electronic ballast, the clamping circuit is turned on and the bus voltage is clamped at a second preset voltage.
4. The lighting circuit according to claim 1, wherein: It also includes a power supply device, the input end of which is connected to the busbar and is used to draw power from the busbar to generate a power supply voltage, and the power supply voltage is used to power the lighting circuit; When the input end of the lighting circuit is connected to the electronic ballast, the supply voltage is within a preset power supply range.
5. The lighting circuit according to claim 2, wherein: The clamping circuit includes a diode, a cathode of the diode is connected to a cathode of the load, and an anode of the diode is grounded.
6. The lighting circuit according to claim 3, wherein: The clamping circuit includes a switching tube. When the discrimination signal indicates that the input end of the rectifier circuit is connected to the electronic ballast, the switching tube is constantly turned on.
7. The lighting circuit according to claim 1, wherein: The driving device includes a detection module, a leakage protection module and a constant current controller. The input end of the detection module is connected to one of the input ends of the rectifier circuit and outputs a discrimination signal. The discrimination signal indicates whether the input end of the rectifier circuit is connected to the electronic ballast or the mains; The input end of the leakage protection module is connected to one of the input ends or the output end of the rectifier circuit. When the discrimination signal indicates that the input end of the rectifier circuit is connected to the mains, the leakage protection module performs leakage detection and outputs an enable signal representing the leakage detection result. The constant current controller receives the discrimination signal, the enable signal and a current feedback signal representing the load current, and generates a switch control signal to control the main power tube to operate in different modes.
8. The lighting circuit according to claim 7, characterized in that: When the discrimination signal indicates that the input end of the rectifier circuit is connected to the mains, the leakage protection module is enabled to work. When the leakage protection module detects that there is no leakage, it outputs an enable signal in a high-level valid state to the constant current controller, and when it detects that there is leakage, it outputs an enable signal in a low-level invalid state to the constant current controller.
9. The lighting circuit according to claim 7, characterized in that: When the discrimination signal indicates that the input end of the rectifier circuit is connected to the mains, When the enable signal output by the leakage protection module is in a low-level invalid state, the switch control signal controls the main power tube to operate in a shutdown mode; When the enable signal of the leakage protection module is in a high-level active state, the switch control signal controls the main power tube to operate in a switch mode.
10. The lighting circuit according to claim 7, characterized in that: The detection module determines whether the input end of the rectifier circuit is connected to the mains or the electronic ballast according to the frequency of the input signal.