CN209930555U

CN209930555U - LED drive circuit

Info

Publication number: CN209930555U
Application number: CN201822207134.7U
Authority: CN
Inventors: 林星宇; 张腾; 蔡拥军; 姚云龙
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2020-01-10
Anticipated expiration: 2028-12-26

Abstract

The embodiment of the utility model discloses a LED drive circuit for driving a first LED lamp and a second LED lamp, which comprises a voltage detection module for providing a first control signal and a second control signal according to the input voltage of a power supply terminal; the first path selection module is used for selecting one of a first current path and a third current path according to a first control signal, the first current path is positioned between the power supply end and the anode of the first LED lamp, and the third current path is positioned between the cathode of the second LED lamp and the anode of the first LED lamp; and the second path selection module is used for selectively switching on or switching off a second current path according to the first control signal and the second control signal, the second current path is positioned between the cathode of the second LED lamp and the ground, and the LED driving circuit can be suitable for different input voltage ranges by utilizing the switching of the connection mode of the LED load.

Description

LED drive circuit

Technical Field

The utility model relates to a LED lighting technology field, concretely relates to LED drive circuit.

Background

Compared with the traditional Light source, the Light Emitting Diode (LED) has the advantages of small volume, energy saving, long service life, high brightness, environmental protection and the like, and is widely used for indoor and outdoor illumination.

The brightness of the LED lamp is related to the driving current, and the corresponding driving schemes are a linear driving scheme and a switching driving scheme. The two respectively adopt the modes of a linear regulating transistor and a switch control transistor to regulate the driving current.

Fig. 1 shows a schematic circuit diagram of an LED driving circuit according to the prior art. As shown in fig. 1, the LED driving circuit 100 includes an ac current source 101, a rectifier bridge 102, an input capacitor Cin, a current sampling resistor Rs, and a linear constant current module 110. An input voltage Vin is provided between two output terminals of the rectifier bridge 102. The LED lamp 103 is connected in series with the linear constant current module 110 and the current sampling resistor Rs between two output terminals of the rectifier bridge 103.

The linear constant current module 110 includes a power tube Q1 and an amplifier 111. The amplifier 111 compares a current sampling signal obtained by the current sampling resistor Rs with a reference voltage Vref, generates a driving signal according to a difference between the current sampling signal and the reference voltage Vref, and controls a driving current flowing through the power transistor Q1. After the circuit is stabilized, the value of the driving current controlled by the linear constant current module 100 is Vref/Rs.

In the LED driving circuit, the input voltage Vin is required to be greater than the load voltage of the LED lamp, otherwise, the rated current cannot be output. Meanwhile, because the voltage drop on the linear constant current chip is the difference value between the input voltage and the output load voltage, the power consumption on the linear constant current system chip is directly related to the input voltage, and the higher the input voltage is, the lower the efficiency is. In order to ensure sufficient luminous efficiency, the input voltage range of the conventional LED driving circuit is generally 220Vac to 240Vac or 110Vac to 130Vac, which results in very limited application of the LED driving circuit.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention is directed to provide an LED driving circuit, which is suitable for different input voltage ranges.

According to the utility model provides a LED drive circuit for drive first LED lamp and second LED lamp, include: the voltage detection module is used for providing a first control signal and a second control signal according to the input voltage of the power supply end; the first path selection module is used for selecting one of a first current path and a third current path according to the first control signal, wherein the first current path is positioned between a power supply end and the anode of the first LED lamp, and the third current path is positioned between the cathode of the second LED lamp and the anode of the first LED lamp; and the second path selection module is used for selectively switching on or switching off a second current path according to the first control signal and the second control signal, and the second current path is positioned between the cathode of the second LED lamp and the ground.

Preferably, the LED driving circuit further includes: and the linear constant current module is used for controlling the current values of the first to third current paths.

Preferably, the LED driving circuit further includes: a diode having an anode connected to the cathode of the second LED lamp and a cathode connected to the anode of the first LED lamp.

Preferably, the first path selection module and the second path selection module are configured to select a current path according to the first control signal and the second control signal, so that the first LED lamp and the second LED lamp are switched to be one of a parallel connection or a series connection.

Preferably, the linear constant current module includes: the first power tube and the sampling resistor are connected between the cathode of the first LED lamp and the ground in series, the control end of the first power tube is used for receiving a linear driving signal, and the middle node of the first power tube and the sampling resistor is used for providing a sampling signal; the first end of the second power tube is connected to the cathode of the second LED lamp, the second end of the second power tube is connected to the middle node of the first power tube and the sampling resistor, and the control end of the second power tube is used for receiving the linear driving signal; and the constant current control unit is used for providing the linear driving signal according to the sampling signal.

Preferably, the first power tube is used for controlling the first current path or the third current path, and the second power tube is used for controlling the second current path.

Preferably, the first path selecting module includes: a third power tube, wherein the first end is connected to the power supply end, and the second end is connected to the anode of the first LED lamp; a first end of the first resistor is connected with the control end of the third power tube, and a second end of the first resistor is connected with the first end of the third power tube; the fourth power tube and the second resistor are connected between the control end of the third power tube and the ground, and the control end of the fourth power tube receives the first control signal; and the anode of the voltage stabilizing tube is connected to the second end of the third power tube, and the cathode of the voltage stabilizing tube is connected to the control end of the third power tube.

Preferably, the second path selecting module includes: a fifth power tube, a control end of which is used for receiving the second control signal, a second end of which is connected to the control end of the second power tube, and a first end of which is used for receiving the linear driving signal; and a control end of the sixth power tube is used for receiving the first control signal, a first end of the sixth power tube is connected to a first node between the fifth power tube and the second power tube, and a second end of the sixth power tube is grounded.

Preferably, when the input voltage of the power supply terminal is greater than a preset value, the voltage detection module outputs the valid first control signal and the invalid second control signal, and when the input voltage of the power supply terminal is less than or equal to the preset value, the voltage detection module outputs the invalid first control signal and the valid second control signal.

Preferably, when the first control signal is valid and the second control signal is invalid, the third power tube disconnects the first current path and turns on the third current path, the fifth power tube is turned off and the sixth power tube is turned on, the sixth power tube pulls down the potential of the first node, the second power tube disconnects the second current path, and when the first control signal is invalid and the second control signal is valid, the third power tube disconnects the third current path and turns on the first current path, the fifth power tube is turned on, the sixth power tube is turned off and the second power tube turns on the second current path.

The utility model discloses LED drive circuit adopts first current path to provide first electric current for first LED lamp, adopts second current path to provide the second electric current for second LED to and adopt the third current path to provide the third electric current for first LED lamp and second LED lamp, thereby realize first LED lamp with the parallelly connected power supply of second LED lamp and first LED lamp with the power supply is established ties to second LED lamp. The method can adopt a simple circuit structure to realize flexible configuration of the connection mode of the first LED lamp and the second LED lamp.

In a preferred embodiment, the voltage detection module switches the connection mode of the first LED lamp and the second LED lamp according to the input voltage of the power supply terminal. And when the input voltage of the power supply end is less than or equal to a preset value, the first LED lamp and the second LED are switched to be in parallel power supply. And when the input voltage of the power supply end is greater than a preset value, the first LED lamp and the second LED are switched to be in series power supply. The first LED lamp and the second LED lamp are used as loads and are automatically switched into one of parallel connection and series connection according to the input voltage, so that the LED driving circuit is suitable for the input voltage in various voltage ranges, and the production cost of manufacturers is saved. Meanwhile, the circuit volume can be reduced, the reliability and the service life can be improved, the utilization rate of the lamp beads can be improved, the cost of the whole machine can be reduced, and the efficiency can be improved.

In a preferred embodiment, the first power tube is used for controlling the current value flowing through the first LED lamp, the second power tube is used for controlling the current value flowing through the second LED lamp, and the first power tube and the second power tube are driven in a synchronous control mode, so that the current equalizing effect of two current paths is better, and the service life of the LED lamp is prolonged.

In a preferred embodiment, the third power tube is driven in a floating mode, and a voltage regulator tube is connected between the grid electrode and the source electrode of the third power tube, so that the overhigh voltage drop between the grid electrode and the source electrode of the third power tube can be prevented, and the service life of the third power tube is prolonged.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing embodiments of the present invention with reference to the following drawings, in which:

fig. 1 shows a schematic circuit diagram of an LED driving circuit according to the prior art.

Fig. 2 shows a schematic block diagram of an LED drive circuit according to an embodiment of the present invention;

fig. 3 shows a schematic circuit diagram of an LED driving circuit according to an embodiment of the present invention.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, and procedures have not been described in detail so as not to obscure the present invention. The figures are not necessarily drawn to scale.

In this application, the term "LED lamp" is, for example, an LED lamp string formed by connecting a plurality of LEDs in series. If multiple LEDs are formed into a string of LEDs, the cathode of the previous LED in the string is connected to the anode of the next LED. The anode of the LED lamp refers to the anode of the first LED lamp in the LED lamp string, and the cathode of the LED lamp refers to the cathode of the last LED lamp in the LED lamp string.

The present invention may be presented in a variety of forms, some of which are described below.

Fig. 2 shows a schematic circuit diagram of an LED driving circuit according to an embodiment of the present invention. As shown in fig. 2, the LED driving circuit 200 includes an ac current source 201, a rectifier bridge 202, an input capacitor Cin, a diode D1, a voltage detection module 210, a linear constant current module 220, a first path selection module 230, and a second path selection module 240. The rectifier bridge 202 is used to rectify the alternating current into direct current. An input voltage Vin is provided between two output terminals of the rectifier bridge 202. The input capacitor Cin smoothly filters the input voltage Vin.

The voltage detection module 210 is connected to a first output terminal of the rectifier bridge 202 to receive the input voltage Vin. The voltage detecting module 210 is used for providing a first control signal SW1 and a second control signal SW2 according to the input voltage Vin, wherein the first control signal SW1 and the second control signal SW2 are inverse signals.

When the input voltage Vin of the power supply terminal is greater than the predetermined value, the voltage detection module 210 outputs an active first control signal SW1 (the first control signal SW1 is at a high level) and an inactive second control signal SW2 (the second control signal SW2 is at a low level); when the input voltage Vin of the power supply terminal is less than or equal to the predetermined value, the voltage detection module 210 outputs an invalid first control signal SW1 (the first control signal SW1 is at a low level) and an valid second control signal SW2 (the second control signal SW2 is at a high level).

The first path selection module 230, the LED lamp 204, and the linear constant current module 220 are connected in series between a high potential end of the input voltage Vin and ground. The LED lamp 203 and the linear constant current module 220 are connected in series between a high potential end of the input voltage Vin and ground.

The first path selection module 230 is configured to select one of a first current path between a high potential end of the input voltage Vin and an anode of the LED lamp 204 and a third current path between a cathode of the LED lamp 203 and the anode of the LED lamp 204. The second path selection module 240 is used to selectively control the on and off of a second current path, which is located between the cathode of the LED lamp 203 and the ground.

The LED driving circuit 200 further includes a diode D1, an anode of the diode D1 is connected to a cathode of the LED lamp 203, and a cathode is connected to an anode of the LED lamp 204, thereby ensuring unidirectional flow of the third current I3. The anode voltage V1 and the cathode voltage V2 of the diode D1 are used for on and off control of the third current path by the first path selection module 230.

The first path selection module 230 is connected to the voltage detection module 210 to receive the first control signal SW 1. The second path selection module 240 is connected to the voltage detection module 210 to receive the first control signal SW1 and the second control signal SW 2.

The linear constant current module 220 is used for controlling the current values on the first to third current paths. In some embodiments, the linear constant current module 220 is connected to the voltage detection module 210, and controls the current flowing through the

LED lamps

203 and 204 according to the reference voltage provided by the voltage detection module 210.

When the alternating voltage is low, the current provided by the rectifier bridge 202 flows through the first current path and the second current path respectively, the third current path is disconnected, and the LED lamp 203 and the LED lamp 204 operate in parallel. The first current I1 flows from the first output terminal of the rectifier bridge 202, through the first path selection module 230, the LED lamp 204, the linear constant current module 220, and then returns to the second output terminal of the rectifier bridge 202. The linear constant current module 220 is used for controlling the current value of the first current I1. The second current I2 flows from the first output terminal of the rectifier bridge 202, through the LED lamp 203 and the linear constant current module 220, and then returns to the second output terminal, i.e. the ground terminal, of the rectifier bridge 202. The linear constant current module 220 controls the current value of the second current I2. At this time, the diode D1 is off and no current flows in the third current path.

When the ac voltage is high, the current provided by the rectifier bridge 202 flows through the third current path, the first current path and the second current path are disconnected, and the LED lamp 203 and the LED lamp 204 operate in series. The third current I3 flows from the first output terminal of the rectifier bridge 202, through the LED lamp 203, the LED lamp 204 and the linear constant current module 220, and then returns to the second output terminal of the rectifier bridge 202. The linear constant current module 220 controls the current value of the third current I3. At this time, the diode D1 is turned on, and a current flows in the third current path.

Fig. 3 shows a schematic circuit diagram of an LED driving circuit according to an embodiment of the present invention. As shown in fig. 3, the linear constant current module 220 includes a sampling resistor Rs, a power transistor Q1, and a power transistor Q2. A first terminal of the power transistor Q1 is connected to the cathode of the LED lamp 204, a second terminal of the power transistor Q1 is connected to a first terminal of the sampling resistor Rs, and a control terminal of the power transistor Q1 is configured to receive the linear driving signal Vbrs. The linear driving signal Vbrs is used for controlling the power transistor Q1. A first terminal of the power transistor Q2 is connected to the cathode of the LED lamp 203, a second terminal of the power transistor Q2 is connected to a first terminal of the sampling resistor Rs, and a control terminal of the power transistor Q2 is connected to the second path selection module 240. The current sampling resistor Rs has a first terminal for providing a sampling signal Vcs and a second terminal connected to ground.

The power transistor Q1 is used to control the current value on the first current path or the third current path, and the power transistor Q2 is used to control the current value on the second current path.

The linear constant current module 220 further includes a constant current control unit 221, and the constant current control unit 221 is configured to compare the sampling signal Vcs with a reference voltage and provide a linear driving signal Vbrs according to a comparison result. In some embodiments, the constant current control unit 221 is connected to the voltage detection module 210, and the voltage detection module 210 is configured to provide a reference voltage to the constant current control unit 221. The first path selection module 230 includes: power tubes Q3 and Q4, a resistor R1 and a resistor R2, and a voltage regulator tube ZD 1. The power tube Q3 is located on the first current path and is connected between the high potential end of the input voltage Vin and the anode of the LED lamp 204. The resistor R1 has a first terminal connected to the node P2 and a control terminal of the power transistor Q3, and a second terminal connected to a first terminal of the power transistor Q3. The anode of the voltage-regulator tube ZD1 is connected with the second end of the power tube Q3, and the cathode is connected with the control end of the power tube Q3, so as to prevent the voltage drop between the control end and the second end of the power tube Q3 from being too high. The power transistor Q4 and the resistor R2 are connected in series between the node P2 and ground, and the control terminal of the power transistor Q4 is configured to receive the first control signal SW 1.

In this embodiment, the first path selection module 230 is used to control the turn-on and turn-off of the power transistor Q3, which in turn is used for selective turn-on of one of the first current path and the third current path.

The second path selection module 240 includes power transistors Q5 and Q6. The control terminal of the power transistor Q5 is configured to receive the second control signal SW2, the second terminal of the power transistor Q5 is connected to the control terminal of the power transistor Q2, and the first terminal of the power transistor Q5 is configured to receive the linear driving signal Vbrs. The control terminal of the power transistor Q6 is used for receiving a first control signal SW1, the first terminal of the power transistor Q6 is connected to a node P1 between the power transistors Q2 and Q5, and the second terminal of the power transistor Q6 is grounded.

In this embodiment, the second path selection module 240 is configured to control the power transistor Q2 to be turned on and off, such that the second current path is turned on and off.

When the ac voltage is low, the first control signal SW1 is at a low level, the second control signal SW2 is at a high level, the power transistor Q4 is turned off, the power transistor Q3 is turned on, the cathode voltage of the diode D1 is greater than the anode voltage, the diode D1 is turned off in the reverse direction, the current flows through the power transistor Q3, the first current path is turned on, and the third current path is turned off. Meanwhile, the power tube Q5 is turned on, the power tube Q6 is turned off, the power tube Q5 provides the driving signal Vbrs to the node P1, the potential of the node P1 rises, the power tube Q2 is turned on, current flows through the power tube Q2, the second current path is turned on, and the LED lamp 203 and the LED lamp 204 are connected in parallel.

When the ac voltage gradually increases to the preset value, the first control signal SW1 is at a high level, the second control signal SW2 is at a low level, the power transistor Q4 is turned on, the power transistor Q4 pulls the potential of the node P2 to ground, the power transistor Q3 is turned off, no current flows through the power transistor Q3, the diode D1 is normally turned on, the first current path is turned off, and the third current path is turned on. Meanwhile, the power tube Q5 is turned off, the power tube Q6 is turned on, the power tube Q6 pulls the potential of the node P1 to the ground, the power tube Q2 is turned off, no current flows in the power tube Q2, the second current path is disconnected, and the LED lamp 203 and the LED lamp 204 are connected in series.

The power transistor Q2 and the power transistor Q1 are used to realize constant current control of the first to third current paths, respectively. The first path selection module 230 and the second path selection module 240 are respectively used for enabling or disabling the power tube Q3 and the power tube Q2, so as to realize the selection of the first current path, the second current path and the third current path, so as to change the connection mode of the LED load.

It should be noted that the embodiments of the present invention do not limit the types of the power transistors Q1-Q6, and the power transistors Q1-Q6 may be enhancement-mode NMOS (N-Metal-Oxide-Semiconductor) or depletion-mode NMOS (N-Metal-Oxide-Semiconductor).

To sum up, the utility model discloses LED drive circuit adopts first current path to provide first electric current for first LED lamp, adopts second current path to provide the second electric current for second LED to and adopt the third current path to provide the third electric current for first LED lamp and second LED lamp, thereby realize first LED lamp with the parallelly connected power supply of second LED lamp and first LED lamp with the power supply is established ties to second LED lamp. The method can adopt a simple circuit structure to realize flexible configuration of the connection mode of the first LED lamp and the second LED lamp.

In a preferred embodiment, the voltage detection module switches the connection mode of the first LED lamp and the second LED lamp according to an input voltage of a power supply terminal. And when the input voltage of the power supply end is less than or equal to a preset value, the first LED lamp and the second LED are switched to be connected in parallel. And when the input voltage of the power supply end is greater than a preset value, the first LED lamp and the second LED are switched to be connected in series. The first LED lamp and the second LED lamp are used as loads and are automatically switched into one of parallel connection and series connection according to the input voltage, so that the LED driving circuit is suitable for the input voltage in various voltage ranges, and the production cost of manufacturers is saved. Meanwhile, the volume of the circuit can be reduced, the reliability is improved, the service life is prolonged, the utilization rate of the lamp beads is improved, the cost of the whole machine is reduced, and the efficiency is improved.

In a preferred embodiment, the linear constant current modules are adopted to control the current values on the first to third current paths, and the first to third current paths share one linear constant current module, so that the number of constant current control units is reduced, and the circuit cost is reduced while the constant current driving is realized.

In accordance with the present invention, as set forth above, these embodiments do not set forth all of the details nor limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The protection scope of the present invention should be subject to the scope defined by the claims of the present invention.

Claims

1. An LED driving circuit for driving a first LED lamp and a second LED lamp, the LED driving circuit comprising:

the voltage detection module is used for providing a first control signal and a second control signal according to the input voltage of the power supply end;

the first path selection module is used for selecting one of a first current path and a third current path according to the first control signal, wherein the first current path is positioned between a power supply end and the anode of the first LED lamp, and the third current path is positioned between the cathode of the second LED lamp and the anode of the first LED lamp;

and the second path selection module is used for selectively switching on or switching off a second current path according to the first control signal and the second control signal, and the second current path is positioned between the cathode of the second LED lamp and the ground.

2. The LED driving circuit according to claim 1, further comprising: and the linear constant current module is used for controlling the current values of the first to third current paths.

3. The LED driving circuit according to claim 2, further comprising: a diode having an anode connected to the cathode of the second LED lamp and a cathode connected to the anode of the first LED lamp.

4. The LED driving circuit according to claim 3, wherein the first and second path selection modules are configured to select a current path according to the first and second control signals such that the first and second LED lamps are switched to one of a parallel connection or a series connection.

5. The LED driving circuit according to claim 2, wherein the linear constant current module comprises:

the first power tube and the sampling resistor are connected between the cathode of the first LED lamp and the ground in series, the control end of the first power tube is used for receiving a linear driving signal, and the middle node of the first power tube and the sampling resistor is used for providing a sampling signal;

the first end of the second power tube is connected to the cathode of the second LED lamp, the second end of the second power tube is connected to the middle node of the first power tube and the sampling resistor, and the control end of the second power tube is used for receiving the linear driving signal; and

and the constant current control unit is used for providing the linear driving signal according to the sampling signal.

6. The LED driving circuit according to claim 5, wherein the first power transistor is configured to control the first current path or the third current path, and the second power transistor is configured to control the second current path.

7. The LED driving circuit according to claim 6, wherein the first path selection module comprises:

a third power tube, wherein the first end is connected to the power supply end, and the second end is connected to the anode of the first LED lamp;

a first end of the first resistor is connected with the control end of the third power tube, and a second end of the first resistor is connected with the first end of the third power tube;

the fourth power tube and the second resistor are connected between the control end of the third power tube and the ground, and the control end of the fourth power tube receives the first control signal; and

and the anode of the voltage stabilizing tube is connected to the second end of the third power tube, and the cathode of the voltage stabilizing tube is connected to the control end of the third power tube.

8. The LED driving circuit according to claim 7, wherein the second path selection module comprises:

a fifth power tube, a control end of which is used for receiving the second control signal, a second end of which is connected to the control end of the second power tube, and a first end of which is used for receiving the linear driving signal; and

and a control end of the sixth power tube is used for receiving the first control signal, a first end of the sixth power tube is connected to a first node between the fifth power tube and the second power tube, and a second end of the sixth power tube is grounded.

9. The LED driver circuit according to claim 8,

when the input voltage of the power supply end is larger than a preset value, the voltage detection module outputs the effective first control signal and the ineffective second control signal,

when the input voltage of the power supply end is smaller than or equal to a preset value, the voltage detection module outputs the invalid first control signal and the valid second control signal.

10. The LED driver circuit according to claim 9,

when the first control signal is valid, and the second control signal is invalid, the third power tube disconnects the first current path, and connects the third current path, the fifth power tube is turned off, the sixth power tube is turned on, the sixth power tube pulls down the potential of the first node, and the second power tube turns off the second current path,

when the first control signal is invalid, and the second control signal is valid, the third power tube disconnects the third current path, and switches on the first current path, the fifth power tube is switched on, the sixth power tube is switched off, and the second power tube switches on the second current path.