US-20260129731-A1 - LEAKAGE PROTECTION CIRCUIT

US20260129731A1US 20260129731 A1US20260129731 A1US 20260129731A1US-20260129731-A1

Abstract

The present disclosure provides a leakage protection circuit, relating to the field of light-emitting diode (LED) technologies and including a power supply circuit, a step-down circuit, an LED circuit, and a detection circuit. The power supply circuit includes an input terminal connected to output pins of a power supply terminal and an output terminal connected to an input terminal of the step-down circuit and an input terminal of the LED circuit. The step-down circuit includes an output terminal connected to the detection circuit. The detection circuit is connected to the output pins of the power supply terminal and the LED circuit, and is configured to control a working status of the LED circuit based on a real-time voltage difference between the output pins of the power supply terminal and the reference voltage output by the step-down circuit.

Inventors

Zongtai Huang
Shijun Fan
Junjie Zhao
Jiaxiong Qiu
Huifeng Feng

Assignees

FOSHAN ELECTRICAL AND LIGHTING CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20251030
Priority Date: 20241231

Claims (10)

1 . A leakage protection circuit, comprising a power supply circuit, a step-down circuit, a light-emitting diode (LED) circuit, and a detection circuit; wherein the power supply circuit comprises an input terminal connected to output pins of a power supply terminal and an output terminal connected to an input terminal of the step-down circuit and an input terminal of the LED circuit, and is configured to rectify output power from the power supply terminal to output supply power to the step-down circuit and the LED circuit; the step-down circuit comprises an output terminal connected to the detection circuit, and is configured to step down the supply power output by the power supply circuit, to output a reference voltage to the detection circuit; and the detection circuit is connected to the output pins of the power supply terminal and the LED circuit, and is configured to control a working status of the LED circuit based on a real-time voltage difference between the output pins of the power supply terminal and the reference voltage output by the step-down circuit.
2 . The leakage protection circuit according to claim 1 , wherein the detection circuit comprises two voltage difference detection modules, a control module, and a switch module, the control module is provided with two real-time sampling terminals and one reference sampling terminal, and the voltage difference detection modules, the real-time sampling terminals, and two groups of output pins of the power supply terminal are in a one-to-one correspondence; the voltage difference detection module is connected to the corresponding group of output pins to detect a real-time voltage difference between the corresponding group of output pins and control, based on the real-time voltage difference, a detection signal output by the voltage difference detection module; the real-time sampling terminal is connected to the corresponding voltage difference detection module to obtain the detection signal; the reference sampling terminal is connected to the output terminal of the step-down circuit to obtain the reference voltage; and the control module comprises an output terminal connected to the switch module, and is configured to control an on-off state of the switch module based on the detection signal and the reference voltage.
3 . The leakage protection circuit according to claim 2 , wherein the voltage difference detection module comprises a rectifier bridge and an optocoupler; the rectifier bridge is connected to the corresponding group of output pins to rectify output power between the output pins; and the optocoupler comprises an input terminal connected to the rectifier bridge and an output terminal connected to the control module, and is configured to control an on-off state of the optocoupler based on a real-time voltage difference of rectified output power from the rectifier bridge.
4 . The leakage protection circuit according to claim 2 , wherein the switch module comprises a first switch, and the first switch comprises a control electrode connected to the output terminal of the control module, one electrode connected to the LED circuit, and the other electrode connected to the power supply circuit.
5 . The leakage protection circuit according to claim 2 , wherein the control module comprises a second switch and a third switch; the second switch is connected to one of the real-time sampling terminals of the control module and the reference sampling terminal of the control module, and is configured to adjust an on-off state of the second switch based on the detection signal obtained by the one of the real-time sampling terminals and the reference voltage obtained by the reference sampling terminal; the third switch is connected to the other real-time sampling terminal of the control module and an output terminal of the second switch, and is configured to adjust an on-off state of the third switch based on the detection signal obtained by the other real-time sampling terminal and an output signal of the second switch; and an output terminal of the third switch is connected to the switch module, the on-off state of the third switch controls the on-off state of the switch module, and the on-off state of the switch module controls the working status of the LED circuit.
6 . The leakage protection circuit according to claim 5 , wherein when the second switch and the third switch are turned on, the switch module is turned on such that the power supply circuit, the LED circuit, and the detection circuit form an LED loop and the LED circuit works; and when the second switch and/or the third switch are/is turned off, the switch module is turned off to disconnect the LED circuit from the detection circuit.
7 . The leakage protection circuit according to claim 5 , wherein the second switch comprises a control electrode connected to an output terminal of one of the voltage difference detection modules through one of the real-time sampling terminals, a first electrode connected to the output terminal of the step-down circuit through the reference sampling terminal, and a second electrode connected to a first electrode of the third switch; and the third switch comprises a control electrode connected to an output terminal of the other voltage difference detection module through the other real-time sampling terminal and a second electrode connected to the switch module.
8 . The leakage protection circuit according to claim 2 , wherein the detection circuit further comprises an anti-interference module, and the control module is connected to the switch module through the anti-interference module.
9 . The leakage protection circuit according to claim 1 , wherein the LED circuit comprises a drive module and an LED module, and the drive module comprises an input terminal connected to an output terminal of the LED module, and is configured to control a working status of the LED module based on the supply power; when the power supply circuit is connected to a ballast, the LED circuit does not work; and when the power supply circuit is connected to a mains supply, the LED circuit controls, based on the supply power, the drive module to be connected to or disconnected from the LED module, to control the working status of the LED circuit.
10 . The leakage protection circuit according to claim 9 , wherein the drive module comprises a drive chip, the drive chip is provided with a detection pin and an open-drain pin, and a built-in switch is disposed in the open-drain pin; the detection pin is connected to the power supply circuit and configured to detect the supply power output by the power supply circuit; and the open-drain pin is connected to the LED module, and the built-in switch is turned on or off based on the supply power to control the drive module to be connected to or disconnected from the LED module.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application claims the benefit of Chinese Patent Application Nos. 202422674394.0 filed on Nov. 1, 2024, 202411990854.9 filed on Dec. 31, 2024 and 202423319314.6 filed on Dec. 31, 2024. All the above are hereby incorporated by reference in their entirety. TECHNICAL FIELD The present disclosure relates to the field of light-emitting diode (LED) technologies, and in particular, to a leakage protection circuit. BACKGROUND At present, a lamp tube may be powered either by direct mains input or by connecting to a ballast. For the mains input, a voltage is typically 220V/50 Hz or the like. If the ballast is connected, connectors at two ends of the lamp tube have a high voltage. In the lighting field, lamp tubes are classified into two types: single-ended input and double-ended input. Single-ended input has connectors of alternating current (AC) input terminals disposed at a same end, whereas double-ended input features connectors at two ends of the lamp tube. Because many lamp sockets still retain double-ended connection interfaces, double-ended input lamp tubes are usually installed during replacement of existing lamp tubes. When installing a lamp tube, an operator usually inserts one end of the lamp tube into a lamp socket first, followed by the other end. At this time, partial conduction may occur. Because the operator's hand needs to grip the end of the lamp tube, accidental contact with conductive metal at the end can easily result in electric shock, compromising operational safety. Therefore, it is particularly important to implement leakage protection for the lamp tube. In the prior art, leakage protection is primarily implemented by connecting a switch transistor to a power input terminal to detect a current flowing through the switch transistor and determine whether leakage occurs. However, the prior art is not effective at all times. When the input terminal is in poor contact, leakage protection circuit of the lamp tube fails, and the operator remains at risk of electric shock. SUMMARY To resolve the foregoing technical problem, the present disclosure provides a leakage protection circuit, which can implement leakage protection. To resolve the foregoing technical problem, the present disclosure provides a leakage protection circuit, including a power supply circuit, a step-down circuit, a light-emitting diode (LED) circuit, and a detection circuit; where the power supply circuit includes an input terminal connected to output pins of a power supply terminal and an output terminal connected to an input terminal of the step-down circuit and an input terminal of the LED circuit, and is configured to rectify output power from the power supply terminal to output supply power to the step-down circuit and the LED circuit; the step-down circuit includes an output terminal connected to the detection circuit, and is configured to step down the supply power output by the power supply circuit, to output a reference voltage to the detection circuit; and the detection circuit is connected to the output pins of the power supply terminal and the LED circuit, and is configured to control a working status of the LED circuit based on a real-time voltage difference between the output pins of the power supply terminal and the reference voltage output by the step-down circuit. As an improvement of the above solution, the detection circuit includes two voltage difference detection modules, a control module, and a switch module, the control module is provided with two real-time sampling terminals and one reference sampling terminal, and the voltage difference detection modules, the real-time sampling terminals, and two groups of output pins of the power supply terminal are in a one-to-one correspondence; the voltage difference detection module is connected to the corresponding group of output pins to detect a real-time voltage difference between the corresponding group of output pins and control, based on the real-time voltage difference, a detection signal output by the voltage difference detection module; the real-time sampling terminal is connected to the corresponding voltage difference detection module to obtain the detection signal; the reference sampling terminal is connected to the output terminal of the step-down circuit to obtain the reference voltage; and the control module includes an output terminal connected to the switch module, and is configured to control an on-off state of the switch module based on the detection signal and the reference voltage. As an improvement of the above solution, the voltage difference detection module includes a rectifier bridge and an optocoupler; the rectifier bridge is connected to the corresponding group of output pins to rectify output power between the output pins; and the optocoupler includes an input terminal connected to the rectifier bridge and an output terminal connected to the control module, and is configured to control an