A constant current LED device with a switch

Abstract

The present invention discloses a constant-current LED device with a switch. The constant-current power supply module is electrically connected to the load module through a wide-load-range switch adaptive module; the positive output terminal of the constant-current power supply module is electrically connected to the positive electrode of the load module to form a first branch; the output terminal of the comparator is electrically connected to the gate of MOS transistor Q2 and the gate of MOS transistor Q3 respectively; the source of MOS transistor Q2 is electrically connected to the negative output terminal of the constant-current power supply module, the drain of MOS transistor Q2 is electrically connected to the first branch through a resistor, the drain of MOS transistor Q2 is also electrically connected to the negative electrode of the electrolytic capacitor, and the positive electrode of the electrolytic capacitor is electrically connected to the first branch; the source of MOS transistor Q3 is electrically connected to the negative electrode of the load module, and the drain of MOS transistor Q3 is electrically connected to the negative electrode of the electrolytic capacitor. The present invention solves the problem that in the existing constant-current LED device, after adding a switch, at the moment of closing the switch, the overshoot current will burn out the LED lamp beads.

Description

Technical Field

[0001] The present invention relates to the technical field of LED lamps, and particularly to a constant-current LED device with a switch. Background Art

[0002] With the rapid development of intelligent LED driver technology, the functions of LED drivers are becoming more and more abundant to meet the different application requirements of different customers. For lamps such as LED table lamps or floor lamps with wall-mounted power supplies, the power supply is directly plugged into the socket on the wall, and the switch is placed at the lamp end, so as to facilitate the user to turn the lamp on and off. In order to be compatible with LED lamp bead strings of different voltages and obtain different powers and different brightnesses, the output voltage range of existing constant-current LED power supplies is large. Thus, if a switch is directly added between the output end of the LED power supply and the LED lamp beads to control the on and off of the LED lamp beads, the overshoot current will burn out the LED lamp beads at the moment when the switch is closed. Summary of the Invention

[0003] Aiming at the above defects, the purpose of the present invention is to provide a constant-current LED device with a switch, which solves the problem that the overshoot current will burn out the LED lamp beads at the moment when the switch is closed in the existing constant-current LED device after adding a switch.

[0004] To achieve this purpose, the present invention adopts the following technical solutions: A constant-current LED device with a switch includes a constant-current power supply module and a load module. The load module includes a switch S1 and an LED lamp bead assembly connected in series. The switch S1 is used to control the on and off of the LED lamp bead assembly;

[0005] It further includes a wide load range switch adaptive module. The constant-current power supply module is electrically connected to the load module through the wide load range switch adaptive module;

[0006] The output end of the constant-current power supply module includes a positive output end and a negative output end. The positive output end of the constant-current power supply module is electrically connected to the positive pole of the load module to form a first branch;

[0007] The wide load range switch adaptive module includes a comparator U2, a resistor R18, a resistor R19, a resistor R20, an electrolytic capacitor EC3, a MOS transistor Q2, and a MOS transistor Q3;

[0008] The negative input pin of the comparator U2 is electrically connected to the output terminal of the constant current power supply module. The positive input pin of the comparator U2 is electrically connected to the negative electrode of the load module. The negative output terminal of the constant current power supply module is electrically connected to the negative electrode of the load module through the resistor R19. The output terminal of the comparator U2 is electrically connected to the gate of the MOS transistor Q2 and the gate of the MOS transistor Q3 respectively. The output terminal of the comparator U2 is also electrically connected to the first branch through the resistor R18;

[0009] The source electrode of the MOS transistor Q2 is electrically connected to the negative output terminal of the constant current power supply module. The drain electrode of the MOS transistor Q2 is electrically connected to the first branch through the resistor R20. The drain electrode of the MOS transistor Q2 is also electrically connected to the negative electrode of the electrolytic capacitor EC3. The positive electrode of the electrolytic capacitor EC3 is electrically connected to the first branch;

[0010] The source electrode of the MOS transistor Q3 is electrically connected to the negative electrode of the load module. The drain electrode of the MOS transistor Q3 is electrically connected to the negative electrode of the electrolytic capacitor EC3.

[0011] It should be noted that the wide load range with switch adaptive module further includes a diode D8. The cathode of the diode D8 is electrically connected to the drain electrode of the MOS transistor Q2. The anode of the diode D8 is electrically connected to the negative electrode of the load module.

[0012] Optionally, the wide load range with switch adaptive module further includes a resistor R15, a resistor R16, a resistor R7, and a diode D7;

[0013] One end of the resistor R15 is electrically connected to the first branch. The other end of the resistor R15 is electrically connected to one end of the resistor R16. The other end of the resistor R16 is electrically connected to the negative input pin of the comparator U2. The other end of the resistor R16 is also electrically connected to one end of the resistor R17. The other end of the resistor R17 is electrically connected to the negative output terminal of the constant current power supply module. The other end of the resistor R15 is also electrically connected to the anode of the diode D7. The cathode of the diode D7 is electrically connected to the negative output terminal of the constant current power supply module.

[0014] Specifically, the positive side power supply pin of the comparator U2 is electrically connected to the positive output terminal of the constant current power supply module. The negative side power supply pin of the comparator U2 is electrically connected to the negative output terminal of the constant current power supply module.

[0015] Preferably, the electrolytic capacitor EC3 is an aluminum electrolytic capacitor.

[0016] It should be noted that the LED lamp bead assembly includes a plurality of LED lamp beads. All the LED lamp beads are connected in series and then connected in series with the switch S1.

[0017] Optionally, the switch S1 is electrically connected to the positive or negative electrode of the LED lamp bead assembly.

[0018] Specifically, the MOS transistor Q2 is an N-channel MOS transistor, and the MOS transistor Q3 is an N-channel MOS transistor.

[0019] One of the above technical solutions has the following beneficial effects: When the switch S1 changes from open to closed to turn on the circuit of the constant-current LED device, because at the moment when the switch S1 is closed, the MOS transistors Q2 and Q3 are still in the off and non-conducting state, the current Iout flows from the positive output terminal of the constant-current power supply module 1 through the switch S1, the LED lamp bead assembly, and the resistor R19. The energy stored in the electrolytic capacitors EC1 and EC2 in the constant-current power supply module 1 is limited by the resistor R19, and the current Iout will not be too large and will not burn out the LED lamp bead assembly. However, at this time, the resistor R19 generates heat because the current Iout flows through it, and the efficiency is low; at the same time, a high voltage greater than 0.3V is generated at the right end of the resistor R19. At this time, the voltage at the positive input terminal of the comparator U2 is higher than the voltage at its negative input terminal, thereby triggering the comparator U2 to output a high voltage at its output terminal, so that the voltage at the gate of the MOS transistor Q2 is greater than the voltage at its source, the drain and source of the MOS transistor Q2 are turned on, and the voltage at the gate of the MOS transistor Q3 is greater than the voltage at its source, the drain and source of the MOS transistor Q3 are turned on. At this time, most of the current flows through the MOS transistors Q2 and Q3, and a very small part of the current passes through the resistor R19, improving the efficiency. The electrolytic capacitor EC3 absorbs the excessive energy stored in the electrolytic capacitors EC1 and EC2 at the moment when the switch S1 is closed, preventing the LED lamp bead assembly from being burned out. Description of the Drawings

[0020] Figure 1 is the circuit diagram of the load module and the wide load range with switch adaptive module of an embodiment of the present invention;

[0021] Figure 2 is the circuit diagram of the power supply module of an embodiment of the present invention;

[0022] Figure 3 is the structural block diagram of an embodiment of the present invention;

[0023] Wherein: 1 power supply module; 2 load module; 3 wide load range with switch adaptive module. Detailed Embodiments

[0024] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0025] The following will describe, in conjunction with Figures 1 to 3 , a constant-current LED device with a switch according to an embodiment of the present invention, which includes a constant-current power supply module 1 and a load module 2. The load module 2 includes a switch S1 and an LED lamp bead assembly connected in series. The switch S1 is used to control the on and off of the LED lamp bead assembly. It further includes a wide-load-range switch adaptive module 3. The constant-current power supply module 1 is electrically connected to the load module 2 through the wide-load-range switch adaptive module 3. The output terminal of the constant-current power supply module 1 includes a positive output terminal and a negative output terminal. The positive output terminal of the constant-current power supply module 1 is electrically connected to the positive electrode of the load module 2 to form a first branch. The wide-load-range switch adaptive module 3 includes a comparator U2, a resistor R18, a resistor R19, a resistor R20, an electrolytic capacitor EC3, a MOS transistor Q2, and a MOS transistor Q3. The negative input pin of the comparator U2 is electrically connected to the output terminal of the constant-current power supply module 1. The positive input pin of the comparator U2 is electrically connected to the negative electrode of the load module 2. The negative output terminal of the constant-current power supply module 1 is electrically connected to the negative electrode of the load module 2 through the resistor R19. The output terminal of the comparator U2 is electrically connected to the gate of the MOS transistor Q2 and the gate of the MOS transistor Q3 respectively. The output terminal of the comparator U2 is also electrically connected to the first branch through the resistor R18. Specifically, the function of the resistor R18 is a pull-up resistor. Since the comparator U2 is an OC output and there is no internal pull-up resistor, when no external pull-up resistor is connected, the output terminal of the comparator U2 cannot output a high level. Therefore, the resistor R18 is used to generate a high level. The source of the MOS transistor Q2 is electrically connected to the negative output terminal of the constant-current power supply module 1. The drain of the MOS transistor Q2 is electrically connected to the first branch through the resistor R20. The drain of the MOS transistor Q2 is also electrically connected to the negative electrode of the electrolytic capacitor EC3. The positive electrode of the electrolytic capacitor EC3 is electrically connected to the first branch. The source of the MOS transistor Q3 is electrically connected to the negative electrode of the load module 2. The drain of the MOS transistor Q3 is electrically connected to the negative electrode of the electrolytic capacitor EC3.

[0026] The constant-current power supply module 1 has an existing structure and outputs a constant current Iout. Assuming the rated output voltage is Uout, then the actual output voltage range is generally (50% - 100%)Uout, which is affected by the LED lamp bead assembly. The no-load voltage is generally 1.2 times Uout. As Figure 2As shown, an electrolytic capacitor EC1 and an electrolytic capacitor EC2 for storing energy are electrically connected inside the constant current power supply module 1, and the electrolytic capacitor EC1 and the electrolytic capacitor EC2 are both connected in parallel between the positive output terminal and the negative output terminal of the constant current power supply module 1. As Figure 1 As shown, when the switch S1 is turned off, because there is a resistor R19, the source voltage of the MOS transistor Q3 and the voltage of the positive input pin of the comparator U2 are 0V, so that the voltage at the output terminal of the comparator U2 is 0V. At this time, the voltage at the output terminal of the comparator U2 is lower than 0.3V, so that the drain and source of the MOS transistor Q2 are turned off and not conducting, and the drain and source of the MOS transistor Q3 are turned off and not conducting. The charge of the electrolytic capacitor EC3 is discharged by the resistor R20, and at this time, the electrolytic capacitor EC3 has no voltage and no charge. When the switch S1 changes from off to on and the circuit of the constant current LED device is turned on, because at the moment when the switch S1 is closed, the MOS transistor Q2 and the MOS transistor Q3 are still in the off and non-conducting state, the current Iout flows from the positive output terminal of the constant current power supply module 1 through the switch S1, the LED lamp bead assembly and the resistor R19. The energy stored in the electrolytic capacitor EC1 and the electrolytic capacitor EC2 inside the constant current power supply module 1 is limited by the resistor R19, and the current Iout will not be too large and will not burn out the LED lamp bead assembly. However, at this time, the resistor R19 generates heat because the current Iout flows through it, and the efficiency is low; at the same time, a high voltage greater than 0.3V is generated at the right end of the resistor R19. At this time, the voltage of the positive input pin of the comparator U2 is higher than the voltage of its negative input pin, thereby triggering the comparator U2 to output a high voltage at its output terminal, so that the voltage of the gate of the MOS transistor Q2 is greater than the voltage of its source, the drain and source of the MOS transistor Q2 are conducting, and the voltage of the gate of the MOS transistor Q3 is greater than the voltage of its source, the drain and source of the MOS transistor Q3 are conducting. At this time, most of the current flows through the MOS transistor Q2 and the MOS transistor Q3, and a very small part of the current passes through the resistor R19, improving the efficiency. The electrolytic capacitor EC3 absorbs the excessive energy stored in the electrolytic capacitor EC1 and the electrolytic capacitor EC2 at the moment when the switch S1 is closed, preventing the LED lamp bead assembly from being burned out. Compared with the existing constant voltage LED lamp beads, the efficiency is improved. In addition, the use of low-voltage switch control can improve safety.

[0027] In some embodiments, the wide load range with switch adaptive module 3 further includes a diode D8. The cathode of the diode D8 is electrically connected to the drain of the MOS transistor Q2, and the anode of the diode D8 is electrically connected to the negative electrode of the load module 2. The function of the diode D8 is to disconnect the electrolytic capacitor EC3 from the circuit loop when the switch S1 is turned off, so that the electric charge of the electrolytic capacitor EC3 is discharged by the resistor R20, so that when the switch S1 is closed again, the electrolytic capacitor EC3 can absorb the excessive energy stored in the electrolytic capacitors EC1 and EC2.

[0028] It should be noted that the wide load range with switch adaptive module 3 further includes a resistor R15, a resistor R16, a resistor R7 and a diode D7. One end of the resistor R15 is electrically connected to the first branch, the other end of the resistor R15 is electrically connected to one end of the resistor R16, the other end of the resistor R16 is electrically connected to the negative input pin of the comparator U2, and the other end of the resistor R16 is also electrically connected to one end of the resistor R17. The other end of the resistor R17 is electrically connected to the negative output terminal of the constant current power supply module 1, and the other end of the resistor R15 is also electrically connected to the anode of the diode D7. The cathode of the diode D7 is electrically connected to the negative output terminal of the constant current power supply module 1. The resistors R15, R16, R7 and the diode D7 provide a reference voltage of about 0.2V to the negative input pin of the comparator U2, and the reference voltage can be adjusted by adjusting the resistance values of the resistors R15 and R16. After determining the resistance values of the resistors R15 and R16, the voltage of the negative input pin of the comparator U2 remains fixed. At this time, as long as the voltage of the positive input pin of the comparator U2 is changed, the on / off of the comparator U2 can be controlled.

[0029] Optionally, the positive power supply pin of the comparator U2 is electrically connected to the positive output terminal of the constant current power supply module 1, and the negative power supply pin of the comparator U2 is electrically connected to the negative output terminal of the constant current power supply module 1. The output of the constant current power supply module 1 is used to supply power to the comparator U2, and there is no need to set up an additional power supply, thus reducing the cost.

[0030] Specifically, the electrolytic capacitor EC3 is an aluminum electrolytic capacitor. The aluminum electrolytic capacitor uses an aluminum cylinder as the negative electrode, which contains a liquid electrolyte, and a bent aluminum strip is inserted as the positive electrode. Its characteristic is large capacitance, and it is suitable for power supply filtering or low-frequency circuits.

[0031] Preferably, the LED lamp bead assembly includes a plurality of LED lamp beads, and all the LED lamp beads are connected in series and then connected in series with the switch S1. The LED lamp bead assembly can not only be provided with only one LED lamp bead, but also be an LED lamp bead string formed by connecting a plurality of LED lamp beads in series, so as to meet the usage requirements of users.

[0032] In some embodiments, the switch S1 is electrically connected to the positive or negative pole of the LED lamp bead assembly. By electrically connecting the switch S1 to the positive or negative pole of the LED lamp bead assembly, the on and off of the LED lamp bead assembly can be controlled by turning the switch S1 on and off.

[0033] It should be noted that the MOS transistor Q2 is an N-channel MOS transistor, and the MOS transistor Q3 is an N-channel MOS transistor. The conduction and cut-off of the N-channel MOS transistor are controlled by the gate-source voltage. When the voltage at the gate is greater than the voltage at the source, the N-channel MOS transistor conducts, that is, the source and the drain conduct.

[0034] Other components and operations of a constant-current LED device with a switch according to an embodiment of the present invention are known to those of ordinary skill in the art and will not be described in detail here.

[0035] In the description of this specification, the descriptions referring to the terms "embodiment", "example", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0036] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A constant-current LED device with a switch, comprising a constant-current power module and a load module. The load module includes a series-connected switch S1 and an LED lamp bead assembly. The switch S1 is used to control the lighting and extinguishing of the LED lamp bead assembly, and is characterized in that: It further includes a wide-load-range switch adaptive module. The constant-current power module is electrically connected to the load module through the wide-load-range switch adaptive module; The output terminal of the constant-current power module includes a positive output terminal and a negative output terminal. The positive output terminal of the constant-current power module is electrically connected to the positive electrode of the load module to form a first branch; The wide-load-range switch adaptive module includes a comparator U2, a resistor R18, a resistor R19, a resistor R20, an electrolytic capacitor EC3, a MOS transistor Q2, and a MOS transistor Q3; The negative input pin of the comparator U2 is electrically connected to the output terminal of the constant-current power module. The positive input pin of the comparator U2 is electrically connected to the negative electrode of the load module. The negative output terminal of the constant-current power module is electrically connected to the negative electrode of the load module through the resistor R19. The output terminal of the comparator U2 is respectively electrically connected to the gate of the MOS transistor Q2 and the gate of the MOS transistor Q3. The output terminal of the comparator U2 is also electrically connected to the first branch through the resistor R18; The source of the MOS transistor Q2 is electrically connected to the negative output terminal of the constant-current power module. The drain of the MOS transistor Q2 is electrically connected to the first branch through the resistor R20. The drain of the MOS transistor Q2 is also electrically connected to the negative electrode of the electrolytic capacitor EC3. The positive electrode of the electrolytic capacitor EC3 is electrically connected to the first branch; The source of the MOS transistor Q3 is electrically connected to the negative electrode of the load module. The drain of the MOS transistor Q3 is electrically connected to the negative electrode of the electrolytic capacitor EC3; When the switch S1 is closed instantaneously, a voltage greater than 0.3V is generated at the connection end of the resistor R19 and the load module. At this time, the voltage of the positive input pin of the comparator U2 is higher than the voltage of its negative input pin, causing the MOS transistor Q2 and the MOS transistor Q3 to conduct.

2. The constant-current LED device with a switch according to claim 1, wherein: The wide-load-range switch adaptive module further includes a diode D8. The cathode of the diode D8 is electrically connected to the drain of the MOS transistor Q2. The anode of the diode D8 is electrically connected to the negative electrode of the load module.

3. The constant current LED device with a switch according to claim 1, characterized in that: The wide-load-range switch adaptive module further includes a resistor R15, a resistor R16, a resistor R17, and a diode D7; One end of the resistor R15 is electrically connected to the first branch. The other end of the resistor R15 is electrically connected to one end of the resistor R16. The other end of the resistor R16 is electrically connected to the negative input pin of the comparator U2. The other end of the resistor R16 is also electrically connected to one end of the resistor R17. The other end of the resistor R17 is electrically connected to the negative output terminal of the constant-current power module. The other end of the resistor R15 is also electrically connected to the anode of the diode D7. The cathode of the diode D7 is electrically connected to the negative output terminal of the constant-current power module.

4. The constant current LED device with a switch according to claim 1, wherein: The positive power supply pin of the comparator U2 is electrically connected to the positive output terminal of the constant current power supply module, and the negative power supply pin of the comparator U2 is electrically connected to the negative output terminal of the constant current power supply module.

5. The constant current LED device with a switch according to claim 1, characterized in that: The electrolytic capacitor EC3 is an aluminum electrolytic capacitor.

6. The constant current LED device with a switch according to claim 1, wherein: The LED lamp bead assembly includes a plurality of LED lamp beads, and all the LED lamp beads are connected in series and then connected in series with the switch S1.

7. The constant current LED device with a switch according to claim 1, characterized in that: The switch S1 is electrically connected to the positive or negative pole of the LED lamp bead assembly.

8. A constant current LED device with a switch according to claim 1, characterized in that: The MOS transistor Q2 is an N-channel MOS transistor, and the MOS transistor Q3 is an N-channel MOS transistor.

Images