Electric leakage protection circuit compatible with commercial power and ballast

Abstract

The invention discloses an electric leakage protection circuit compatible with a mains supply and a ballast, which relates to the technical field of LEDs and comprises a power supply circuit, a step-down circuit, a driving circuit, an LED circuit and a detection circuit, the input end of the power supply circuit is connected to the output pin of the power supply end, the output end of the power supply circuit is connected with the input end of the step-down circuit, the detection end of the driving circuit and the input end of the LED circuit, and the power supply circuit is used for rectifying the output power supply of the power supply end so as to output the power supply to the step-down circuit, the driving circuit and the LED circuit; the input end of the driving circuit is connected with the output end of the LED circuit, and the driving circuit is used for controlling the working state of the LED circuit according to the power supply; the output end of the step-down circuit is connected with the detection circuit, and the step-down circuit is used for carrying out step-down processing on the power supply output by the power circuit to output reference voltage to the detection circuit; and the detection circuit is connected with the output pins of the power supply end, the driving circuit and the LED circuit respectively, and is used for controlling the working states of the driving circuit and the LED circuit according to the real-time voltage between the output pins of the power supply end and the reference voltage output by the step-down circuit. According to the invention, the working state of the LED circuit can be controlled according to the real-time voltage and the reference voltage, thereby realizing anti-creeping protection.

Description

Technical Field

[0001] The invention relates to the technical field of LEDs, and in particular to a leakage protection circuit compatible with mains power and a ballast. Background Art

[0002] At present, the lamp can be powered by AC power directly or by a ballast. When AC power is selected, the AC power is generally 220V / 50HZ or other voltages; when a ballast is selected, high voltage electricity exists at the connectors at both ends of the lamp.

[0003] In the field of lighting, lamps are divided into two types: single-ended input and double-ended input. Single-ended input actually sets the AC input connectors at the same end, while double-ended input sets them at both ends of the lamp. Since many lamp holders still retain double-ended access interfaces, double-ended input lamps are generally used when replacing and installing the original lamps.

[0004] During the installation of the lamp tube, the operator usually inserts one end of the lamp tube into the lamp holder first, and then inserts the other end. At this time, partial connection may occur. Since the operator's hand needs to hold the end of the lamp tube, if the human body accidentally touches the conductive metal at the end, electric shock may occur easily, affecting the safety of operation. Therefore, it is particularly important to implement leakage protection for the lamp tube.

[0005] In the prior art, a switch tube is connected to the power input end to detect the current flowing through the switch tube, thereby determining whether there is leakage to achieve leakage protection. However, the prior art is not always effective. When the input end has poor contact, the leakage protection circuit will fail, and the operator is still at risk of electric shock. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a leakage protection circuit which is compatible with the mains and the ballast and can realize leakage protection.

[0007] In order to solve the above technical problems, the present invention provides a leakage protection circuit compatible with AC power and ballast, comprising: a power supply circuit, a step-down circuit, a drive circuit, an LED circuit and a detection circuit; the input end of the power supply circuit is connected to the output pin of the power supply end, and the output end of the power supply circuit is respectively connected to the input end of the step-down circuit, the detection end of the drive circuit and the input end of the LED circuit, for rectifying the output power of the power supply end to output power supply to the step-down circuit, the drive circuit and the LED circuit; the input end of the drive circuit is connected to the output end of the LED circuit, for controlling the working state of the LED circuit according to the power supply; the output end of the step-down circuit is connected to the detection circuit, for step-down the power supply output by the power supply circuit to output a reference voltage to the detection circuit; the detection circuit is respectively connected to the output pin of the power supply end, the drive circuit and the LED circuit, for controlling the working state of the drive circuit and the LED circuit according to the real-time voltage between the output pins of the power supply end and the reference voltage output by the step-down circuit.

[0008] As an improvement of the above scheme, the detection circuit includes two bandpass filter modules, a comparison module and a switch module, the comparison module is provided with two real-time sampling terminals and two reference sampling terminals, and the two groups of output pins of the bandpass filter module, the real-time sampling terminal, the reference sampling terminal and the power supply terminal correspond to each other one by one; the bandpass filter module is connected to a corresponding group of output pins to filter the output power supply between the corresponding group of output pins; the real-time sampling terminal is connected to the corresponding bandpass filter module to detect the real-time voltage between the corresponding group of output pins; the reference sampling terminal is connected to the output terminal of the step-down circuit to obtain the reference voltage; the output terminal of the comparison module is connected to the switch module to control the on-off state of the switch module according to the real-time voltage and the reference voltage.

[0009] As an improvement of the above solution, the bandpass filtering module includes two diodes connected in series in an anti-phase manner, and the real-time sampling end of the comparison module is connected between the two diodes.

[0010] As an improvement of the above scheme, the switch module includes a first switch, a control end of the first switch is connected to the output end of the comparison module, an electrode end of the first switch is connected to the drive circuit and the LED circuit, and the other electrode end of the first switch is connected to the power supply circuit.

[0011] As an improvement of the above scheme, the comparison module includes a first comparator, a second comparator, a second switch and a third switch; an input end of the first comparator is connected to a real-time sampling end of the comparison module, and the other input end of the first comparator is connected to a reference sampling end of the comparison module, and the first comparator is used to control the on-off state of the second switch according to a real-time voltage detected by a real-time sampling end and a reference voltage obtained by a reference sampling end; an input end of the second comparator is connected to another real-time sampling end of the comparison module, and the other input end of the second comparator is connected to another reference sampling end of the comparison module, and the second comparator is used to control the on-off state of the third switch according to the real-time voltage detected by another real-time sampling end and the reference voltage obtained by another reference sampling end; the second switch, the third switch and the switch module are connected in sequence, and the on-off state of the second switch and the third switch controls the on-off state of the switch module, and the on-off state of the switch module controls the working state of the drive circuit and the LED circuit.

[0012] As an improvement of the above scheme, when the second switch and the third switch are turned on, the switch module is turned on so that the drive circuit does not work and the power supply circuit, LED circuit and detection circuit form an LED loop, and the LED circuit works; when the second switch and / or the third switch are turned off, the switch module is turned off so that the LED circuit is disconnected from the detection circuit.

[0013] As an improvement of the above scheme, the control electrode of the second switch is connected to the output end of the first comparator, the first electrode of the second switch is connected to the output end of the step-down circuit, and the second electrode of the second switch is connected to the first electrode of the third switch; the control electrode of the third switch is connected to the output end of the second comparator, and the second electrode of the third switch is connected to the switch module.

[0014] As an improvement of the above solution, the detection circuit further includes an anti-interference module, and the comparison module and the switch module are connected via the anti-interference module.

[0015] As an improvement of the above scheme, when the power supply circuit is connected to the ballast, the drive circuit does not work; when the power supply circuit is connected to the mains, the drive circuit controls the on-off state between the drive circuit 5 and the LED circuit according to the power supply to control the working state of the LED circuit.

[0016] As an improvement of the above-mentioned scheme, the driving circuit includes a driving chip, which is provided with a detection pin and an open-drain pin, and the open-drain pin is provided with a built-in switch; the detection pin is connected to the power supply circuit and is used to detect the power supply output by the power supply circuit; the open-drain pin is connected to the LED circuit, and the built-in switch switches the on-off state according to the power supply to control the on-off state between the driving circuit 5 and the LED circuit.

[0017] The beneficial effects of implementing the present invention are:

[0018] The leakage protection circuit of the present invention, which is compatible with the mains and the ballast, takes the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage between the output pins of the power supply end with the reference voltage, and uses the voltage factor as the judgment basis to realize accurate leakage detection from the voltage angle, thereby greatly improving the accuracy of detection, thereby effectively controlling the on-off state of the LED circuit, playing a role in preventing leakage, and ensuring the safety of people;

[0019] Furthermore, the leakage protection circuit of the present invention introduces control elements such as comparators and switch tubes to achieve layer-by-layer comparison of electrical signals and flexible switching of circuits, thereby more accurately controlling the on and off state of the LED circuit with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the leakage protection circuit of the present invention which is compatible with the mains and the ballast;

[0021] Figure 2 It is a circuit diagram of an embodiment of the leakage protection circuit of the present invention which is compatible with the mains and the ballast;

[0022] Figure 3 It is a circuit diagram of an embodiment of a step-down circuit in a leakage protection circuit compatible with mains power and ballast of the present invention;

[0023] Figure 4 It is a circuit diagram of another embodiment of the step-down circuit in the leakage protection circuit compatible with the mains and the ballast of the present invention;

[0024] Figure 5 It is another structural schematic diagram of the leakage protection circuit of the present invention which is compatible with the mains and the ballast. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that the directional terms such as up, down, left, right, front, back, inside, outside, etc. that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and are not specific limitations of the present invention.

[0026] See also Figure 1 , Figure 1 The specific structure of the leakage protection circuit of the present invention which is compatible with the mains and the ballast is shown, which includes a power supply circuit 1, a step-down circuit 2, a drive circuit 5, an LED circuit 3 and a detection circuit 4. Specifically:

[0027] The input end of the power supply circuit 1 is connected to the output pin of the power supply end, and the output end of the power supply circuit 1 is respectively connected to the input end of the step-down circuit 2, the detection end of the drive circuit 5 and the input end of the LED circuit 3, so as to rectify the output power of the power supply end to output the power supply to the step-down circuit 2, the drive circuit 5 and the LED circuit 3;

[0028] The input end of the driving circuit 5 is connected to the output end of the LED circuit 3, and is used to control the working state of the LED circuit 3 according to the power supply;

[0029] The output end of the step-down circuit 2 is connected to the detection circuit 4, and is used to step down the power supply output by the power supply circuit 1 to output a reference voltage to the detection circuit 4;

[0030] The detection circuit 4 is connected to the output pin of the power supply end, the drive circuit 5 and the LED circuit 3 respectively, and is used to control the working state of the drive circuit 5 and the LED circuit 3 according to the real-time voltage between the output pins of the power supply end and the reference voltage output by the step-down circuit 2.

[0031] It should be noted that the leakage protection circuit of the present invention which is compatible with AC power and ballast can be applied to both AC power and ballast at the same time, so the power supply end can be either the AC power supply end or the ballast power supply end; at the same time, the leakage protection circuit of the present invention can realize leakage protection of the ballast and AC power at the same time.

[0032] In the prior art, the leakage protection circuit compatible with the mains and ballast detects the rectified electrical signal to achieve leakage protection. Different from the prior art, the leakage protection circuit compatible with the mains and ballast of the present invention uses the electrical signal before rectification (i.e., the electrical signal between the output pins) as the detection target, and uses the voltage factor as the judgment basis, to achieve accurate leakage detection from the voltage perspective, greatly improving the accuracy of detection.

[0033] The power supply circuit 1, the step-down circuit 2, the LED circuit 3, the drive circuit 5 and the detection circuit 4 are described in detail below in conjunction with specific embodiments:

[0034] 1. Power supply circuit 1

[0035] like Figure 2As shown, in this embodiment, the power supply circuit 1 includes a first rectifier bridge BD1, a second rectifier bridge BD2, a second diode D2, a third diode D3, a seventh diode D7, an eighth diode D8, a second capacitor C2, an eighth capacitor C8 and input ports F1, F2, F3 and F4;

[0036] One AC input end of the first rectifier bridge BD1 is connected to the input port F1, the other AC input end is connected to the input port F2, the negative end of the DC output is connected to the step-down circuit 2 and the LED circuit 3, and the positive end of the DC output is grounded; the anode of the second diode D2 is connected to the input port F1, and the cathode is connected to the drive circuit 5; the anode of the third diode D3 is connected to the input port F2, and the cathode is connected to the drive circuit 5; one end of the second capacitor C2 is connected to the input port F1, and the other end is connected to the input port F2;

[0037] Similarly, one AC input end of the second rectifier bridge BD2 is connected to the input port F3, the other AC input end is connected to the input port F4, the DC output negative end is connected to the step-down circuit 2 and the LED circuit 3, and the DC output positive end is grounded; the anode of the seventh diode D7 is connected to the input port F3, and the cathode is connected to the drive circuit 5; the anode of the eighth diode D8 is connected to the input port F4, and the cathode is connected to the drive circuit 5; one end of the eighth capacitor C8 is connected to the input port F3, and the other end is connected to the input port F4.

[0038] When the present invention is applied to a ballast, the input ports F1 , F2 , F3 and F4 can be connected to four pins of the ballast.

[0039] When the present invention is applied to AC power, any two input ports can be selected to connect two pins of the AC power, for example, input ports F1 and F2, or input ports F3 and F4, or input ports F1 and F3, or input ports F1 and F4, or input ports F2 and F3, or input ports F2 and F4.

[0040] Therefore, the power supply circuit 1 can rectify the output power of the power supply end to output a stable power supply to the step-down circuit 2 and the LED circuit 3 .

[0041] 2. Buck circuit 2

[0042] like Figure 2 As shown, in this embodiment, the step-down circuit 2 includes a voltage-dividing resistor group (a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5), a first capacitor C1 and a first voltage-stabilizing diode D1; wherein, one end of the first resistor R1 is connected to the power supply circuit 1, and the other end is grounded through the second resistor R2, the third resistor R3, the fourth resistor R4 and the fifth resistor R5 in sequence, the fifth resistor R5 is connected in parallel with the first capacitor C1 and the first voltage-stabilizing diode D1, the positive electrode of the first voltage-stabilizing diode D1 is grounded, and the negative electrode is connected to the detection circuit 4.

[0043] Therefore, the power supply output by the power supply circuit 1 can be stepped down by the step-down circuit 2 and converted into a reference voltage of 5V for use by the detection circuit 4 .

[0044] In other embodiments, resistors of different numbers and resistance values ​​may be selected for voltage reduction according to actual needs.

[0045] like Figure 3 As shown, in this embodiment, the voltage-dividing resistor group includes four resistors (a second resistor R2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5) connected in series.

[0046] In other embodiments, the voltage may be reduced by using a voltage-reducing chip.

[0047] like Figure 4 As shown, in this embodiment, the buck circuit 2 includes a buck chip U2, an eleventh diode D11, a twelfth diode D12, a third inductor L3, a fourth inductor L4, a sixteenth capacitor C16, a seventeenth capacitor C17, a second polarity capacitor CE2, a third polarity capacitor CE3, a fourth polarity capacitor CE4, a fortieth resistor R40, a forty-first resistor R41 and a current limiting resistor RS1, wherein:

[0048] The ground pin GND of the buck chip U2 is connected to the cathode of the twelfth diode D12, the clock pin SCL and the power supply pin VCC are respectively connected to the cathode of the eleventh diode D11, the open drain pin DRAIN is connected to the power supply circuit 1 through the third inductor L3, and the chip select pin CS is connected to the cathode of the twelfth diode D12 through the current limiting resistor RS1;

[0049] The anode of the twelfth diode D12 is grounded, the cathode is connected to the detection circuit 4 via the fourth inductor L4 and connected to the cathode of the eleventh diode D11 via the seventeenth capacitor C17, and the anode of the eleventh diode D11 is connected to the detection circuit 4;

[0050] One end of the 40th resistor R40 is connected to the detection circuit 4, and the other end is grounded. The 40th resistor R40, the 16th capacitor C16 and the second polarity capacitor CE2 are connected in parallel with each other.

[0051] The forty-first resistor R41 is connected in parallel with the third inductor L3; the positive electrode of the fourth polarity capacitor CE4 is connected to the open-drain pin DRAIN, and the negative electrode is grounded; the positive electrode of the third polarity capacitor CE3 is connected to the power supply circuit 1, and the negative electrode is grounded.

[0052] It should be noted that when connected to the AC power, no matter it is single-ended access to the input ports F1 and F2, or single-ended access to the input ports F3 and F4, or double-ended input, the voltage after rectification by the first rectifier bridge DB1 and the second rectifier bridge DB2 is 310VDC, which meets the working state of the buck chip U2; therefore, the buck chip U2 can work normally, play the role of step-down constant current, and supply a constant reference voltage to the detection circuit 4.

[0053] Therefore, in applications, different step-down circuits 2 may be used to step down the power output by the power supply circuit 1 according to actual needs, and no limitation is made here.

[0054] 3. LED circuit 3

[0055] like Figure 2 As shown, in this embodiment, the LED circuit 3 includes a plurality of light emitting diodes (LED1 . . . LEDN) connected in series.

[0056] 4. Driving circuit 5

[0057] The leakage protection circuit compatible with AC power and ballast of the present invention can be applied to AC power and ballast at the same time, wherein when the power supply circuit 1 is connected to the ballast, the drive circuit 5 does not work; when the power supply circuit 1 is connected to the AC power, the drive circuit 5 controls the on-off state between the drive circuit 5 and the LED circuit 3 according to the power supply to control the working state of the LED circuit 3.

[0058] For example, when the driving circuit 5 does not detect leakage, the driving circuit 5 is connected to the LED circuit 3, and the driving circuit 5 drives the LED circuit 3, thereby ensuring a constant current supply to the LED circuit 3;

[0059] For another example, when the driving circuit 5 detects a leakage, the driving circuit 5 is disconnected from the LED circuit 3 and the LED circuit 3 is short-circuited.

[0060] In some embodiments, the driving circuit 5 includes a driving chip U1, which is provided with a detection pin REC and an open-drain pin DRAIN, and the open-drain pin DRAIN is provided with a built-in switch; the detection pin REC is connected to the power circuit 1, and is used to detect the power supply output by the power circuit 1. The open-drain pin DRAIN is connected to the LED circuit 3, and the built-in switch switches the on-off state according to the power supply to control the on-off state between the driving circuit 5 and the LED circuit 3.

[0061] like Figure 2As shown, in this embodiment, the driving circuit 5 includes a driving chip U1, a first transformer coil T1, a sixth diode D6, a voltage stabilizing diode TVS1, a first polarity capacitor CE1, a seventh capacitor C7, a ninth capacitor C9, a tenth capacitor C10, an eighth resistor R8, a ninth resistor R9, an eleventh resistor R11, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a seventeenth resistor R17 and an eighteenth resistor R18, wherein: an open-drain pin DRAIN of the driving chip U1 is connected to the cathode of the LED circuit 3 through the first transformer coil T1; the compilation pin ISP is grounded through the seventeenth resistor R17 and the eighteenth resistor R18 respectively; the ground pin GND is grounded and connected to the positive pole of the sixth diode D6 through the ninth capacitor C9. The cathode of the sixth diode D6 is connected to the anode of the LED circuit 3; the detection pin REC is connected to the power supply circuit 1 through the fourteenth resistor R14 and the thirteenth resistor R13 in sequence, and is grounded through the voltage stabilizing diode TVS1 and the fifteenth resistor R15 respectively; the power supply pin VIN is connected to the anode of the LED circuit 3 through the eighth resistor R8; one end of the tenth capacitor C10 is grounded, and the other end is respectively connected to the detection circuit 4 and the cathode of the LED circuit 3; one end of the ninth resistor R9 is connected to the anode of the LED circuit 3, and the other end is connected to the open-drain pin DRAIN through the seventh capacitor C7; one end of the first polarity capacitor CE1 is connected to the anode of the LED circuit 3, and the other end is connected to the cathode of the LED circuit 3, and the eleventh resistor R11 is connected in parallel with the first polarity capacitor CE1;

[0062] It should be noted that the detection pin REC of the driver chip U1 has an input current detection function; when the power supply is greater than 72MA, the driver chip U1 turns on the built-in switch of the open-drain pin DRAIN; when the power supply is less than 72MA, the driver chip U1 turns off the built-in switch of the open-drain pin DRAIN. Preferably, the driver chip U1 can be JW1830, JW1831, JW1832 or other similar solutions, but is not limited thereto.

[0063] 5. Detection circuit 4

[0064] like Figure 2 As shown, the detection circuit 4 includes two bandpass filter modules 41, a comparison module 42 and a switch module 43. The comparison module 42 is provided with two real-time sampling terminals and two reference sampling terminals. The two groups of output pins of the bandpass filter module 41, the real-time sampling terminal, the reference sampling terminal and the power supply terminal correspond to each other.

[0065] The bandpass filter module 41 is connected to a corresponding group of output pins to filter the output power between the corresponding group of output pins;

[0066] The real-time sampling terminal is connected to the corresponding band-pass filter module 41 to detect the real-time voltage between the corresponding set of output pins;

[0067] The reference sampling terminal is connected to the output terminal of the step-down circuit 2 to obtain a reference voltage;

[0068] The output end of the comparison module 42 is connected to the switch module 43 and is used to control the on / off state of the switch module 43 according to the real-time voltage and the reference voltage.

[0069] Therefore, through the cooperation among the bandpass filter module 41, the comparison module 42 and the switch module 43, the switch module 43 can be accurately switched on and off according to the real-time voltage between the output pins and the reference voltage of the step-down circuit 2, with high precision.

[0070] The bandpass filter module 41, the comparison module 42 and the switch module 43 are described in detail below:

[0071] (1) Bandpass filter module

[0072] The bandpass filter module 41 includes two diodes connected in series in an anti-phase manner, and the real-time sampling terminal of the comparison module 42 is connected between the two diodes.

[0073] like Figure 2 As shown, in this embodiment, a bandpass filter module 41 includes a fourth diode D4 and a fifth diode D5; another bandpass filter module 42 includes a ninth diode D9 and a tenth diode D10. Wherein:

[0074] The anode of the fourth diode D4 is connected to the input port F1, the cathode of the fourth diode D4 is connected to the cathode of the fifth diode D5, and the anode of the fifth diode D5 is connected to the input port F2;

[0075] Similarly, the anode of the ninth diode D9 is connected to the input port F3 , the cathode of the ninth diode D9 is connected to the cathode of the tenth diode D10 , and the anode of the tenth diode D10 is connected to the input port F4 .

[0076] During operation, a real-time sampling terminal A may be provided between the fourth diode D4 and the fifth diode D5, and another real-time sampling terminal B may be provided between the ninth diode D9 and the tenth diode D10.

[0077] Therefore, by setting the real-time sampling terminals A and B, the real-time voltage between the output pins can be effectively detected, thereby obtaining the power status between the output pins in real time.

[0078] (2) Comparison module

[0079] like Figure 2As shown, in this embodiment, the comparison module 42 includes a first comparator U1A, a second comparator UIB, a second switch Q2 and a third switch Q3; wherein, one input end of the first comparator U1A is connected to a real-time sampling end of the comparison module 42, and the other input end of the first comparator U1A is connected to a reference sampling end of the comparison module 42, and the first comparator U1A is used to control the on-off state of the second switch Q2 according to a real-time voltage detected by a real-time sampling end and a reference voltage obtained by a reference sampling end; one input end of the second comparator UIB is connected to another real-time sampling end of the comparison module 42, and the other input end of the second comparator UIB is connected to another reference sampling end of the comparison module 42, and the second comparator UIB is used to control the on-off state of the third switch Q3 according to the real-time voltage detected by another real-time sampling end and the reference voltage obtained by another reference sampling end; the second switch Q2, the third switch Q3 and the switch module 43 are connected in sequence, and the on-off states of the second switch Q2 and the third switch Q3 control the on-off state of the switch module 43, and the on-off state of the switch module 43 controls the working state of the driving circuit 5 and the LED circuit 3.

[0080] It should be noted that when the second switch Q2 and the third switch Q3 are turned on, the switch module 43 is turned on, so that the drive circuit 5 does not work and the power supply circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 works; when the second switch Q2 and / or the third switch Q3 are turned off, the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4.

[0081] For further information, see Figure 5 The control electrode of the second switch Q2 is connected to the output end of the first comparator U1A, the first electrode of the second switch Q2 is connected to the output end of the buck circuit 2, and the second electrode of the second switch Q2 is connected to the first electrode of the third switch Q3; the control electrode of the third switch Q3 is connected to the output end of the second comparator UIB, and the second electrode of the third switch Q3 is connected to the switch module 43.

[0082] For example, when the first comparator U1A and the second comparator UIB both output a low level, the second switch Q2, the third switch Q3 and the switch module 43 are turned on, so that the power circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 works;

[0083] When the first comparator U1A outputs a high level and the second comparator UIB outputs a low level, the second switch Q2 is turned off, the third switch Q3 is turned on, and the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4;

[0084] When the first comparator U1A outputs a low level and the second comparator UIB outputs a high level, the second switch Q2 is turned on, the third switch Q3 is turned off, and the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4;

[0085] When the first comparator U1A and the second comparator UIB both output high level, the second switch Q2 , the third switch Q3 and the switch module 43 are turned off, so that the LED circuit 3 is disconnected from the detection circuit 4 .

[0086] It should be noted that the output levels of the first comparator U1A and the second comparator UIB can affect the on / off state of the second switch Q2 and the third switch Q3, but the specific influencing logic can be set according to the actual situation. For example, it can be set as follows: when the first comparator U1A outputs a low level, the second switch Q2 is turned on; for another example, it can be set as follows: when the first comparator U1A outputs a high level, the second switch Q2 is turned on.

[0087] Furthermore, the comparison module 42 also includes a first voltage-dividing resistor group 421, a second voltage-dividing resistor group 422, a third voltage-dividing resistor group 423 and a fourth voltage-dividing resistor group 424; one input end of the first comparator U1A is connected to a real-time sampling end of the comparison module 42 through the first voltage-dividing resistor group 421, and the other input end of the first comparator U1A is connected to a reference sampling end of the comparison module 42 through the second voltage-dividing resistor group 422; one input end of the second comparator UIB is connected to another real-time sampling end of the comparison module 42 through the third voltage-dividing resistor group 423, and the other input end of the second comparator UIB is connected to another reference sampling end of the comparison module 42 through the fourth voltage-dividing resistor group 424.

[0088] It should be noted that in practical applications, voltage-dividing resistors of different numbers and resistance values ​​can be set according to requirements to form the first voltage-dividing resistor group 421 , the second voltage-dividing resistor group 422 , the third voltage-dividing resistor group 423 and the fourth voltage-dividing resistor group 424 .

[0089] like Figure 2 As shown, in this embodiment, the first voltage-dividing resistor group 421 includes the twenty-sixth resistor R26 and the twenty-seventh resistor R27 connected in series, the second voltage-dividing resistor group 422 includes the twenty-fifth resistor R25 and the twenty-ninth resistor R29 connected in series, the third voltage-dividing resistor group 423 includes the thirty-seventh resistor R37 and the thirty-eighth resistor R38 connected in series, and the fourth voltage-dividing resistor group 424 includes the twenty-fourth resistor R24 ​​and the twenty-eighth resistor R28 connected in series.

[0090] (3) Switch module

[0091] like Figure 2As shown, in this embodiment, the switch module 43 includes a first switch Q1, a control end of the first switch Q1 is connected to the output end of the comparison module 42, an electrode end of the first switch Q1 is connected to the drive circuit 5 and the LED circuit 3, and the other electrode end of the first switch Q1 is connected to the power supply circuit 1.

[0092] Therefore, when the first switch Q1 is turned on, the power circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 works; when the first switch Q1 is turned off, the LED circuit 3 and the detection circuit 4 are disconnected.

[0093] It can be seen from the circuit structures of the bandpass filter module 41, the comparison module 42 and the switch module 43 that: Figure 2 In the embodiment shown:

[0094] The non-inverting input terminal of the first comparator U1A is connected to the step-down circuit 2 through the twenty-fifth resistor R25, and is grounded through the twenty-ninth resistor R29. The inverting input terminal of the first comparator U1A is connected to a real-time sampling terminal A through the twenty-sixth resistor R26, and is grounded through the twenty-seventh resistor R27. The output terminal of the first comparator U1A is connected to the gate of the second switch Q2.

[0095] The non-inverting input terminal of the second comparator U1B is connected to the step-down circuit 2 through the twenty-fourth resistor R24 ​​and is grounded through the twenty-eighth resistor R28. The inverting input terminal of the second comparator U1B is connected to another real-time sampling terminal B through the thirty-seventh resistor R37 and is grounded through the thirty-eighth resistor R38. The output terminal of the second comparator U1B is connected to the gate of the third switch Q3.

[0096] The source of the second switch Q2 is connected to the step-down circuit 2 , the drain of the second switch Q2 is connected to the source of the third switch Q3 , the drain of the third switch Q3 is connected to the control electrode of the first switch Q1 , one output end of the first switch Q1 is connected to the LED circuit 3 , and the other end is grounded.

[0097] Furthermore, the detection circuit 4 further includes an anti-interference module 44 , and the comparison module 42 and the switch module 43 are connected via the anti-interference module 44 .

[0098] like Figure 2 As shown, in this embodiment, the anti-interference module 44 includes a 30th resistor R30, a 32nd resistor R32 and an RC circuit (a 33rd resistor R33 and a 13th capacitor C13 connected in parallel with each other); the 30th resistor R30 is connected in series between the comparison module 42 and the switch module 43; one end of the 32nd resistor R32 is connected to the switch module 43, and the other end is connected to the power supply circuit (i.e., grounded); one end of the RC circuit is connected to the comparison module 42, and the other end is connected to the power supply circuit (i.e., grounded).

[0099] Therefore, the anti-interference module 44 can be used to isolate the comparison module 42 from the switch module 43 , thereby avoiding interference to the switch module 43 and improving the accuracy of the switch module 43 .

[0100] Furthermore, the leakage protection circuit compatible with AC power and ballast of the present invention further includes a filter circuit 6, the input end of the filter circuit 6 is connected to the output end of the power circuit 1, and the output end of the filter circuit 6 is connected to the drive circuit 5 and the LED circuit 3 respectively.

[0101] like Figure 2 As described, in this embodiment, the filter circuit 6 includes a first inductor L1, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a fifteenth capacitor C15 and a thermistor RV1; wherein the power supply pin VCC of the driver chip U1 is grounded through the fifth capacitor C5; one end of the thermistor RV1 is connected to the positive electrode of the LED circuit 3, and the other end is grounded; one end of the third capacitor C3 is connected to the power supply circuit 1, and the other end is grounded; one end of the fourth capacitor C4 is connected to the positive electrode of the LED circuit 3, and the other end is grounded; one end of the first inductor L1 is connected to the power supply circuit 1, and the other end is connected to the positive electrode of the LED circuit 3, and the fifteenth capacitor C15 is connected in parallel with the first inductor L1.

[0102] Therefore, the supply voltage output by the power supply circuit 1 can be filtered by the filter circuit 6 to supply power to the drive circuit 5 and the LED circuit 3 .

[0103] The following further describes Figure 2 The leakage detection principle of the embodiment shown:

[0104] 1. Connect the ballast

[0105] When the ballast is input, there is a real-time voltage difference between the input ports F1 and F2. After the real-time voltage is divided by the twenty-sixth resistor R26 and the twenty-seventh resistor R27, it is greater than the 5V divided voltage of the first comparator U1A (where 5V is a vague concept, and the voltage can change according to the change of the output power supply of the power supply end). The first comparator U1A outputs a low level, thereby turning on the second switch Q2. Similarly, there is a real-time voltage difference between the input ports F3 and F4. After the real-time voltage is divided by the thirty-seventh resistor R37 and the thirty-eighth resistor R38, it is greater than the second comparator U1 B's 5V voltage division, the second comparator U1B outputs a low level, so that the third switch Q3 is turned on; the 5V voltage enters the control electrode of the first switch Q1 through the second switch Q2 and the third switch Q3, and the first switch Q1 is turned on, so that the output power of the power supply circuit 1 flows from the negative DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the first inductor L1, the LED circuit 3, the first switch Q1 in sequence, and finally returns to the positive DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 to form an LED loop, so that the LED circuit 3 is lit. At this time, the cathode of the LED circuit 3 is pulled to the ground by the first switch Q1, and the open drain pin DRAIN of the driver chip U1 is equivalent to grounding. At this time, the driver chip U1 does not meet the working conditions and does not participate in the work.

[0106] When one end of the lamp tube falls off, there is no voltage difference between the input ports F1 and F2, or between F3 and F4, and the second switch Q2 or the third switch Q3 is not conducting. Since one of them is not conducting, there is no voltage and current at the control electrode of the first switch Q1, and the first switch Q1 is in the off state, so that the LED loop of the circuit is cut off, making it safe for the installer to touch the other end, thereby preventing leakage.

[0107] 2. Connect to the mains

[0108] When connected to the mains, the single-end or double-end of the power circuit 1 can work normally. When the input ports F1 and F2, or F3 and F4 input the mains, the input voltage is subject to the actual solution, which can be wide voltage, narrow voltage, single voltage, etc. The following uses 220V / 50HZ to explain the working principle:

[0109] When connected to the mains, the voltage input path is input ports F1 and F2, or input ports F3 and F4, or a combination of input ports F1, F2 and F3, F4 (for example, input from F1 and F3, or F1 and F4, or F2 and F3, or F2 and F4); but no matter which method is used, it is input from two pins, and at this time the second switch Q2 or the third switch Q3 is not conducting; because one of them is not conducting, at this time the control electrode of the first switch Q1 has no voltage and current, and the first switch Q1 is in a turned-off state, so that the first switch Q1 does not work and does not affect the operation of the driver chip U1, so that the output power of the power supply circuit 1 flows from the DC output negative end of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the first inductor L1, the LED circuit 3, the open-drain pin DRAIN, the driver chip U1 and the compilation pin ISP in sequence, and finally returns to the DC output positive end of the first rectifier bridge BD1 and the second rectifier bridge BD2 to form an LED loop, so that the LED circuit 3 is normally lit.

[0110] At this time, when one of the input pins is disconnected and contacts a person, since the internal resistance of the person is greater than 500Ω, it is equivalent to connecting a resistor to the detection pin REC of the driver chip U1. At this time, the current of the detection pin REC will decrease, causing the previous state greater than 72MA to change to less than 72MA. At this time, the built-in switch of the open-drain pin DRAIN is closed, so that the LED circuit is cut off, which plays a role in leakage protection.

[0111] To sum up, the leakage protection circuit of the present invention, which is compatible with AC power and ballast, takes the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage and the reference voltage between the output pins of the power supply end, and uses the voltage factor as the judgment basis, thereby realizing accurate detection of leakage from the voltage perspective, greatly improving the accuracy of detection, thereby effectively controlling the on-off state of the LED circuit, playing a role in preventing leakage, and ensuring human safety; further, the leakage protection circuit of the present invention introduces control elements such as comparators and switching tubes, realizes layer-by-layer comparison of electrical signals and flexible switching of circuits, thereby more accurately controlling the on-off state of the LED circuit with high accuracy.

[0112] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A leakage protection circuit compatible with mains and ballast, characterized in that: Including power supply circuit, step-down circuit, drive circuit, LED circuit and detection circuit; The input end of the power supply circuit is connected to the output pin of the power supply end, and the output end of the power supply circuit is respectively connected to the input end of the step-down circuit, the detection end of the drive circuit and the input end of the LED circuit, so as to rectify the output power of the power supply end to output the power supply to the step-down circuit, the drive circuit and the LED circuit; The input end of the driving circuit is connected to the output end of the LED circuit, and is used to control the working state of the LED circuit according to the power supply; The output end of the step-down circuit is connected to the detection circuit, and is used to step down the power supply output by the power supply circuit to output a reference voltage to the detection circuit; The detection circuit is connected to the output pin of the power supply end, the drive circuit and the LED circuit respectively, and is used to control the working state of the drive circuit and the LED circuit according to the real-time voltage between the output pins of the power supply end and the reference voltage output by the step-down circuit.

2. The leakage protection circuit compatible with mains and ballast as claimed in claim 1, characterized in that: The detection circuit includes two bandpass filter modules, a comparison module and a switch module. The comparison module is provided with two real-time sampling terminals and two reference sampling terminals. The bandpass filter module, the real-time sampling terminal, the reference sampling terminal and the two groups of output pins of the power supply terminal correspond to each other. The bandpass filter module is connected to a corresponding group of output pins to filter the output power between the corresponding group of output pins; The real-time sampling terminal is connected to a corresponding band-pass filtering module to detect the real-time voltage between a corresponding set of output pins; The reference sampling terminal is connected to the output terminal of the step-down circuit to obtain a reference voltage; The output end of the comparison module is connected to the switch module, and is used to control the on-off state of the switch module according to the real-time voltage and the reference voltage.

3. The leakage protection circuit compatible with mains and ballast as claimed in claim 2, characterized in that: The bandpass filter module comprises two diodes connected in series in anti-phase, and the real-time sampling end of the comparison module is connected between the two diodes.

4. The leakage protection circuit compatible with mains and ballast as claimed in claim 2, characterized in that: The switch module includes a first switch, a control end of the first switch is connected to the output end of the comparison module, an electrode end of the first switch is connected to the drive circuit and the LED circuit, and another electrode end of the first switch is connected to the power supply circuit.

5. The leakage protection circuit compatible with mains and ballast as claimed in claim 2, characterized in that: The comparison module includes a first comparator, a second comparator, a second switch and a third switch; An input terminal of the first comparator is connected to a real-time sampling terminal of the comparison module, and another input terminal of the first comparator is connected to a reference sampling terminal of the comparison module, and the first comparator is used to control the on-off state of the second switch according to a real-time voltage detected by a real-time sampling terminal and a reference voltage obtained by a reference sampling terminal; One input end of the second comparator is connected to another real-time sampling end of the comparison module, and another input end of the second comparator is connected to another reference sampling end of the comparison module, and the second comparator is used to control the on-off state of the third switch according to the real-time voltage detected by the other real-time sampling end and the reference voltage obtained by the other reference sampling end; The second switch, the third switch and the switch module are connected in sequence, the on-off state of the second switch and the third switch controls the on-off state of the switch module, and the on-off state of the switch module controls the working state of the drive circuit and the LED circuit.

6. The leakage protection circuit compatible with mains and ballast as claimed in claim 5, characterized in that: When the second switch and the third switch are turned on, the switch module is turned on, so that the drive circuit does not work and the power circuit, the LED circuit and the detection circuit form an LED loop, and the LED circuit works; When the second switch and / or the third switch is turned off, the switch module is turned off to disconnect the LED circuit from the detection circuit.

7. The leakage protection circuit compatible with mains and ballast as claimed in claim 5, characterized in that: The control electrode of the second switch is connected to the output end of the first comparator, the first electrode of the second switch is connected to the output end of the step-down circuit, and the second electrode of the second switch is connected to the first electrode of the third switch; The control electrode of the third switch is connected to the output end of the second comparator, and the second electrode of the third switch is connected to the switch module.

8. The leakage protection circuit compatible with mains and ballast as claimed in claim 2, characterized in that: The detection circuit further comprises an anti-interference module, and the comparison module and the switch module are connected via the anti-interference module.

9. The leakage protection circuit compatible with mains and ballast as claimed in claim 1, characterized in that: When the power supply circuit is connected to the ballast, the drive circuit does not work; When the power supply circuit is connected to the mains, the drive circuit controls the on / off state between the drive circuit 5 and the LED circuit according to the power supply to control the working state of the LED circuit.

10. The leakage protection circuit compatible with mains and ballast according to claim 1 or 9, characterized in that: The driving circuit comprises a driving chip, the driving chip is provided with a detection pin and an open-drain pin, and the open-drain pin is provided with a built-in switch; The detection pin is connected to the power circuit and is used to detect the power supply output by the power circuit; The open-drain pin is connected to the LED circuit, and the built-in switch switches the on-off state according to the power supply to control the on-off state between the drive circuit 5 and the LED circuit.

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