Over-current and over-load protection circuit of LED lamp string
By designing an LED string protection circuit including multiple switch transistors, the voltage problems and frequent faults of LED strings are solved when using multiple devices, and timely protection of overcurrent and overload and extension of service life are achieved.
Patent Information
- Application Number
- CN202411911720.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-03-11
AI Technical Summary
When using multiple devices, existing LED light strings are prone to voltage reduction or voltage increase, resulting in shortening or damage to the device's service life, and the existing control methods or structures are complex or single functions, and frequent failures occur.
A protection circuit including the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, and the fourth switching transistor Q4 is designed. When the LED light string is overloaded or short-circuited, the circuit is promptly disconnected through the combination of these switching transistors to avoid fire and extend service life.
It effectively solves the problem of safe use of LED strings, realizes timely protection of overcurrent and overload, extends the service life of the product, and avoids fire.
Smart Images
Figure CN119603823A_ABST
Abstract
Description
[Technical field]
[0001] The invention relates to an LED light string for lighting decoration, and in particular to an overcurrent and overload protection circuit of the LED light string. [Background technology]
[0002] In addition to being used as lighting devices, LED lights can also be used as light sources for advertising light boxes, product working status indicators, electronic signs, and Christmas trees, handicrafts and other lighting decorations. When multiple devices are connected to the existing LED lights, for example, when multiple LED lamp beads are connected to form a Christmas decorative light string, the traditional connection method is mostly parallel or series, and the defects of this single connection method are obvious. In the traditional parallel structure, each device is connected in parallel to the power supply wire, which inevitably leads to the problem of voltage reduction. When multiple devices are used in series, if one of the multiple devices in series fails, it will cause the voltage of other devices to rise, thereby increasing the load of other devices, and greatly shortening the service life of the devices that are still working, and even damaging other devices and causing the entire light string to fail to operate normally. Therefore, the overcurrent and overload control of the LED light string becomes a key factor in the normal and continuous use of the LED light string. However, the existing control methods and devices are either complex in structure or single in function, resulting in frequent failures in actual use. [Summary of the invention]
[0003] The present invention aims to solve the above-mentioned problem and provides an overcurrent and overload protection circuit for an LED light string, which can cut off the circuit by promptly disconnecting the switch transistor of the control circuit when the LED light string is overloaded or short-circuited, so as to avoid fire caused by line faults and extend the service life of the product.
[0004] To achieve the above-mentioned purpose, the present invention provides an overcurrent and overload protection circuit for an LED light string, the overcurrent and overload protection circuit comprising a protection circuit connected to a power supply circuit, the protection circuit comprising a first switch transistor Q1, a second switch transistor Q2, a third switch transistor Q3, and a fourth switch transistor Q4 for preventing the LED light string from overcurrent and overload, the first switch transistor Q1, the second switch transistor Q2, and the fourth switch transistor Q4 are connected in parallel to the input end of the power supply, the third switch transistor Q3 is connected in parallel to the first switch transistor Q1 and the fourth switch transistor Q4, respectively, the protection circuit is connected to an LED light string control circuit, the LED light string control circuit comprises an LED light string positive and negative output circuit, a buck voltage stabilizing circuit and a main control chip U2 connected to the LED light string positive and negative output circuits, and the LED light string control circuit is connected to a wireless receiving circuit for remotely controlling the LED light string.
[0005] The first switch transistor Q1, the second switch transistor Q2 and the fourth switch transistor Q4 of the protection circuit are connected to the external power supply through the resistors R1, R4, R2 and R3 connected in parallel therewith. The third switch transistor Q3 is connected to the first switch transistor Q1 and the fourth switch transistor Q4 respectively, and is connected to the buck stabilizing circuit of the LED light string control circuit through the current limiting resistor RL, the sampling resistor R6 and the resistor R7 connected in parallel therewith.
[0006] The LED light string positive and negative output circuits of the LED light string control circuit include field effect tubes T1, T2, T3, and T4 connected in forward and reverse directions, wherein the collectors of the field effect tubes T1 and T4 are connected, and the collectors of the field effect tubes T2 and T3 are connected, and the LED light strings LED1, LED2, and a resistor R17 are connected in parallel on the connecting wires between the field effect tubes T1 and T4 and between the field effect tubes T2 and T3, and resistors R10, R12, R13, R14, R15, and R16 are connected to the field effect tubes T1, T2, T3, and T4, respectively.
[0007] The buck voltage stabilizing circuit of the LED light string control circuit includes a buck voltage stabilizing chip U1, capacitors C1, C2, C3, C4, a crystal oscillator Y1 and a resistor R8. The capacitors C1, C2, C3, C4 are connected between the buck voltage stabilizing chip U1 and the main control chip U2.
[0008] The main control chip U2 of the LED light string control circuit is connected to the step-down voltage stabilizing circuit via resistor R8, and is connected to the field effect transistor T1 of the LED light string control circuit via resistors R9 and R10. The main control chip U2 is also connected to the RF input interface of the wireless receiving circuit, and an on-off switch SW is connected to the main control chip U2.
[0009] The wireless receiving circuit includes an RF chip U3, a crystal oscillator Y2 connected in parallel to the RF chip U3, inductors L1 and L2 connected in parallel to capacitors C5 and C6 connected to the RF chip U3, and capacitors C7 and C8 connected in parallel to a resistor R18 connected to the RF chip U3. The wireless receiving circuit is connected to the main control chip U2 and is used for wireless remote control of the LED light string.
[0010] The LED light string control circuit is connected to an external LED light string via light string output nodes O1 and O2.
[0011] When the LED light string output nodes O1 and O2 leak or short-circuit, the voltage across the current-limiting resistor RL rises due to the sharp increase in current. When the voltage at node C is lower than the voltage at node B by a certain value, the third switch transistor Q3 is turned on, and the current is limited by resistor R5 and the fourth switch transistor Q4 is turned on. At this time, the voltage at node E is close to zero volts, causing the second switch transistor Q2 to be turned off; at the same time, the high voltage passes through resistors R2 and R3 to the base of the first switch transistor Q1, turning off the first switch transistor Q1 and outputting the voltage at node B. In the suspended state, its extremely small current cannot start the buck regulator chip U1 and causes the buck regulator chip U1 to stop working. Since the resistors R9 and R11 have no current output, the LED light string control circuit is disconnected, thereby realizing overcurrent and overload protection of the LED light string. When the light string returns to normal, the voltage at node C rises, the third switch transistor Q3 is cut off, the node D is suspended, the fourth switch transistor Q4 is cut off, the voltage at node E rises, the second switch transistor Q2 is turned on, and the first switch transistor Q1 is turned on to restore to normal working state.
[0012] The contribution of the present invention is that it effectively solves the problem of safe use of LED light strings. When leakage or short circuit occurs in the output nodes O1 and O2 of the LED light string, the protection circuit of the present invention can turn off the first switch transistor Q1 and stop the buck regulator chip U1 from working by turning on the third switch transistor Q3 and the fourth switch transistor Q4 and turning off the second switch transistor Q2, and disconnect the LED light string control circuit. The LED light string control circuit of the present invention ensures the output current capacity and protection efficiency of the LED light string through the field effect transistors T1, T2, T3, and T4 connected in forward and reverse directions. The wireless receiving circuit of the present invention can wirelessly remotely control the lighting effect and on and off of the LED light string.
Brief Description of the Drawings
[0013] Figure 1 It is a circuit block diagram of the present invention.
[0014] Figure 2 It is a circuit schematic diagram of the present invention. [Specific implementation method]
[0015] The following examples are provided to further explain and illustrate the present invention and do not constitute any limitation to the present invention.
[0016] See also Figure 1 , Figure 2The overcurrent and overload protection circuit of the LED light string of the present invention includes a protection circuit 10, an LED light string control circuit 20 and a wireless receiving circuit 30. The protection circuit 10 is used to prevent the LED light string from overcurrent and overload. It uses a combination of several switching transistors so that when the output nodes O1 and O2 of the LED light string leak or short circuit, the switching transistor can cut off the circuit in time to ensure the safe use of the LED light string. The LED light string control circuit 20 maintains the output current capacity and protection efficiency through forward and reverse circuits. The wireless receiving circuit 30 provides an optional remote control method for the LED light string. The LED light string described in this embodiment refers to a light string in which multiple LED lamp beads are connected to form a lighting decoration, which can be installed on lighting decoration products such as Christmas trees. The present invention will be described in more detail below in conjunction with the accompanying drawings and embodiments.
[0017] like Figure 1 , Figure 2 As shown, the protection circuit 10 includes a first switch transistor Q1, a second switch transistor Q2, a third switch transistor Q3, a fourth switch transistor Q4, resistors R1, R4, R2, R3, R7, a current limiting resistor RL and a sampling resistor R6. The first switch transistor Q1 is a high-output power switch transistor with a power of 100W, and can also be a field effect transistor. The size of the current it carries determines the carrying capacity of the entire circuit. Figure 2 As shown, resistors R2 and R3 are connected in parallel between the first switch transistor Q1 and the second switch transistor Q2. A current limiting resistor RL is also connected in series to the first switch transistor Q1. The resistance value of the current limiting resistor RL determines the magnitude of the protection load leakage and short-circuit current. The higher the resistance value, the smaller the current, and the smaller the resistance value, the larger the current. It also plays a role in limiting the current of the LED light string. In this embodiment, the resistance value of the current limiting resistor RL is 0.1 to 3 ohms. The third switch transistor Q3 is connected in parallel with the first switch transistor Q1 and the fourth switch transistor Q4 via resistor R5, current limiting resistor RL, and sampling resistor R6, respectively. Resistors R1 and R4 are connected in parallel between the first switch transistor Q1, the second switch transistor Q2, and the fourth switch transistor Q4 and the external power supply. The first switch transistor Q1, the second switch transistor Q2, and the fourth switch transistor Q4 are connected to the external power supply via resistors R1, R4, R2, and R3. The first switch transistor Q1 and the third switch transistor Q3 are connected to the buck stabilizing circuit 22 of the LED light string control circuit via a current limiting resistor RL, a sampling resistor R6, and a resistor R7.
[0018] like Figure 2As shown, when the protection circuit 10 is working, when the output nodes O1 and O2 of the LED light string leak or short circuit, the current in the circuit will rise sharply, causing the voltage across the current limiting resistor RL to rise synchronously. When the voltage of node C is about 0.7V lower than the voltage of node B, the third switch transistor Q3 is turned on, and the fourth switch transistor Q4 is turned on after the resistor R5 limits the current. At this time, the voltage of node E is close to 0V, so that the second switch transistor Q2 is immediately cut off. At the same time, the high voltage passes through the resistors R2 and R3 to the base of the first switch transistor Q1, so that the first switch transistor Q1 is disconnected, and the output node B is in a suspended state. Since the extremely low current of node B flows through the resistor R7 to the voltage stabilizing circuit and is lower than the starting voltage of the buck voltage stabilizing chip U1, the buck voltage stabilizing chip U1 stops running, and the resistors R9 and R11 have no output, and finally the light string control circuit 20 stops running, thereby achieving the purpose of protecting the LED light string control circuit and the input power supply. When the LED light string returns to normal, the voltage at node C rises, the voltage difference between node B and node C becomes smaller, the third switch transistor Q3 is disconnected, node D is suspended, the fourth switch transistor Q4 is disconnected, and the voltage at node E rises to turn on the second switch transistor Q2 and reach the bias current of the first switch transistor Q1, thereby turning on the first switch transistor Q1 and restoring the circuit to normal operation.
[0019] like Figure 1 , Figure 2As shown, the protection circuit 10 is connected to the LED light string control circuit 20. The LED light string control circuit 20 includes an LED light string positive and negative output circuit 21, a step-down voltage stabilizing circuit 22 and a main control chip U2, which is connected to an external LED light string through the light string output nodes O1 and O2. The LED light string positive and negative output circuit 21 includes field effect transistors T1, T2, T3, T4 and resistors R9, R10, R11, R12, R13, R14, R15, R16, R17, which can output current in both positive and negative directions. The electrodes of the field effect transistors T1, T2 and the field effect transistors T3 and T4 are reversely connected, and the collectors of the field effect transistors T1 and T4 and the field effect transistors T2 and T3 are connected by wires. The field effect transistors T1, T2, T3, and T4 can also be switch transistors. The LED light string LED1, LED2 and resistor R17 are connected in parallel to the connecting wires of the field effect tubes T1 and T4 and the field effect tubes T2 and T3. The field effect tubes T1, T2, T3 and T4 are respectively connected to resistors R10, R12, R13, R14, R15 and R16. The power of each of the field effect tubes T1, T2, T3 and T4 determines the strength of the output current of the LED light string and the efficiency of protection. In this embodiment, the power of the field effect tubes T1, T2, T3 and T4 is above 1W. The main control chip U2 of the LED light string control circuit is connected to the buck voltage regulator circuit 22 through resistors R8, and is connected to the field effect transistor T1 of the LED light string control circuit through resistors R9 and R10. The main control chip U2 is also connected to the radio frequency input interface of the wireless receiving circuit 30, and an on-off switch SW is connected to the main control chip U2, which is used to disconnect the main control chip U2 from the LED light string control circuit 20 when the protection circuit 10 is closed due to leakage or short circuit, and the buck voltage regulator chip U1 stops running. The main control chip U2 is used to collect data and control the on-off of the circuit for the protection circuit 10, the LED light string control circuit 20 and the wireless receiving circuit 30.
[0020] like Figure 1 , Figure 2As shown, when the LED light string positive and negative output circuit 21 is working, when the 9th pin of the main control chip U2 outputs a high level and the 8th pin outputs a low level, the high level passes through the resistor R9 to limit the current and the resistor R10 triggers the field effect transistor T1. At this time, the collector of the switching transistor Q1 is at a low level, and the resistors R13 and R14 are the lower bias resistor and the upper bias resistor of the field effect transistor T3. When the switching transistor Q1 is at a low level, the resistor R13 triggers the field effect transistor T3, so that the collector of the switching transistor Q2 is at a high level, and the output LED light string LED2 is lit due to the unidirectional conductive characteristics, while the LED light string LED1 is in a reverse cut-off state. When the 9th pin of the main control chip U2 outputs a low level and the 8th pin outputs a high level, the high level is limited by the resistor R11 and triggers the field effect tube T2 through the lower bias resistor R12, so that the collector of the switching transistor Q2 is at a low level. At the same time, the resistors R15 and R16 are the lower bias resistor and the upper bias resistor of the field effect tube T4. When the switching transistor Q2 is at a low level, the resistor R15 triggers the field effect tube T4, so that the switching transistor Q1 is at a high level. The output LED light string LED1 is lit because the LED has a unidirectional conductive characteristic, and the LED light string LED2 is in a reverse cut-off state, thereby realizing the positive and negative non-polar working process of the entire circuit. The resistors R10, R12, R14, and R16 in the positive and negative output circuit of the LED light string are bias resistors, which are used to quickly cut off the field effect tubes T1, T2, T3, and T4. In order to prevent the LED light string output from having residual light, the resistor R17 is used as a discharge resistor.
[0021] like Figure 1 , Figure 2 As shown, the buck voltage stabilizing circuit 22 includes a buck voltage stabilizing chip U1, capacitors C1, C2, C3, C4, a crystal oscillator Y1 and a resistor R8. The capacitors C1, C2, C3, C4 and the crystal oscillator Y1 are connected between the buck voltage stabilizing chip U1 and the main control chip U2. The buck voltage stabilizing chip U1 has a built-in buck voltage stabilizing circuit, which is connected to the protection circuit 10 via a resistor R7, and is connected to the main control chip U2 via a resistor R8 and a capacitor C2, for providing a stable voltage for the protection circuit 10 and the LED light string control circuit 20.
[0022] like Figure 1 , Figure 2As shown, the present invention provides a wireless receiving circuit 30 that can be used selectively. The wireless receiving circuit 30 includes an RF chip U3, a crystal oscillator Y2 connected in parallel to the RF chip U3, inductors L1 and L2 connected in parallel to capacitors C5 and C6 on the RF chip U3, and capacitors C7 and C8 connected in parallel to resistor R18 on the RF chip U3. The wireless receiving circuit 30 is connected to the radio frequency interface of the main control chip U2, and is connected to the antenna ANT through capacitors C5 and C6 and parallel inductors L1 and L2. Users can wirelessly remotely control the functions and opening and closing of the LED light string through the wireless receiving circuit 30.
[0023] Although the present invention is disclosed through the above embodiments, the protection scope of the present invention is not limited thereto. Without departing from the concept of the present invention, any deformation, replacement, etc. made to the above components shall fall within the scope of the claims of the present invention.
Claims
1. An overcurrent and overload protection circuit for an LED light string, characterized in that: The overcurrent and overload protection circuit comprises a protection circuit (10) connected to a power supply circuit, the protection circuit (10) comprising a first switch transistor Q1, a second switch transistor Q2, a third switch transistor Q3, and a fourth switch transistor Q4 for preventing an LED light string from overcurrent and overload, the first switch transistor Q1, the second switch transistor Q2, and the fourth switch transistor Q4 being connected in parallel to an input end of a power supply, the third switch transistor Q3 being connected in parallel to the first switch transistor Q1 and the fourth switch transistor Q4, respectively, the protection circuit being connected to an LED light string control circuit (20), the LED light string control circuit (20) comprising an LED light string positive and negative output circuit (21), a step-down voltage stabilizing circuit (22) connected to the LED light string positive and negative output circuit (21), and a main control chip U2, the LED light string control circuit (20) being connected to a wireless receiving circuit (30) for remotely controlling the LED light string.
2. The overcurrent and overload protection circuit of the LED light string as claimed in claim 1, characterized in that: The first switch transistor Q1, the second switch transistor Q2 and the fourth switch transistor Q4 of the protection circuit (10) are connected to an external power supply via resistors R1, R4, R2 and R3 connected in parallel therewith; the third switch transistor Q3 is connected to the first switch transistor Q1 and the fourth switch transistor Q4 respectively, and is connected to the step-down voltage stabilization circuit (22) of the LED light string control circuit via a current limiting resistor RL, a sampling resistor R6 and a resistor R7 connected in parallel therewith.
3. The overcurrent and overload protection circuit of the LED light string as claimed in claim 1, characterized in that: The LED light string positive and negative output circuit (21) of the LED light string control circuit comprises field effect tubes T1, T2, T3 and T4 connected in positive and negative directions, wherein the collectors of the field effect tubes T1 and T4 are connected, and the collectors of the field effect tubes T2 and T3 are connected, and the LED light string LED1, LED2 and a resistor R17 are connected in parallel on the connecting wires between the field effect tubes T1 and T4 and between the field effect tubes T2 and T3, and the field effect tubes T1, T2, T3 and T4 are respectively connected with resistors R10, R12, R13, R14, R15 and R16.
4. The overcurrent and overload protection circuit of the LED light string as claimed in claim 1, characterized in that: The buck voltage stabilizing circuit (22) of the LED light string control circuit comprises a buck voltage stabilizing chip U1, capacitors C1, C2, C3, C4, a crystal oscillator Y1 and a resistor R8, wherein the capacitors C1, C2, C3, C4 are connected between the buck voltage stabilizing chip U1 and the main control chip U2.
5. The overcurrent and overload protection circuit of the LED light string as claimed in claim 1, characterized in that: The main control chip U2 of the LED light string control circuit is connected to the step-down voltage stabilization circuit (22) via resistors R8, and is connected to the field effect transistor T1 of the LED light string control circuit via resistors R9 and R10. The main control chip U2 is also connected to the radio frequency input interface of the wireless receiving circuit (30), and an on-off switch SW is connected to the main control chip U2.
6. The overcurrent and overload protection circuit of the LED light string as claimed in claim 1, characterized in that: The wireless receiving circuit (30) comprises an RF chip U3, a crystal oscillator Y2 connected in parallel to the RF chip U3, inductors L1 and L2 connected in parallel to capacitors C5 and C6 connected to the RF chip U3, and capacitors C7 and C8 connected in parallel to a resistor R18 connected to the RF chip U3. The wireless receiving circuit (30) is connected to a main control chip U2 and is used for wireless remote control of an LED light string.
7. The overcurrent and overload protection circuit of the LED light string as claimed in claim 1, characterized in that: The LED light string control circuit (20) is connected to an external LED light string via light string output nodes O1 and O2.
8. The overcurrent and overload protection circuit of the LED light string according to any one of claims 1 to 7, characterized in that: When the LED light string output nodes O1 and O2 leak or short-circuit, the voltage across the current-limiting resistor RL rises due to the sharp increase in current. When the voltage at node C is lower than the voltage at node B by a certain value, the third switch transistor Q3 is turned on, and the current is limited by resistor R5 and the fourth switch transistor Q4 is turned on. At this time, the voltage at node E is close to zero volts, causing the second switch transistor Q2 to be turned off; at the same time, the high voltage passes through resistors R2 and R3 to the base of the first switch transistor Q1, turning off the first switch transistor Q1 and outputting the voltage at node B. In the suspended state, its extremely small current cannot start the buck regulator chip U1 and causes the buck regulator chip U1 to stop working. Since the resistors R9 and R11 have no current output, the LED light string control circuit is disconnected, thereby realizing overcurrent and overload protection of the LED light string. When the light string returns to normal, the voltage at node C rises, the third switch transistor Q3 is cut off, the node D is suspended, the fourth switch transistor Q4 is cut off, the voltage at node E rises, the second switch transistor Q2 is turned on, and the first switch transistor Q1 is turned on to restore to normal working state.