LED linear driving circuit and LED device

Abstract

The utility model provides an LED linear driving circuit and an LED device, the connection mode of an LED is automatically adjusted according to the magnitude of an input voltage, when the input voltage is higher than a set voltage, a first constant current module and a second constant current module are disconnected, a first LED load and a second LED load are connected in series, and constant current power supply is performed through a third constant current module; when the input voltage is lower than the set voltage, the third constant-current module works in a switch conduction mode, the first constant-current module supplies power to the second LED load in a constant-current mode, and the second constant-current module supplies power to the first LED load in a constant-current mode. The LED linear driving circuit does not need an electrolytic capacitor, can meet the market requirement of 85-264 Vac full voltage input, and is simple in structure, small in size, light in weight, easy to integrate and convenient for full-patch production.

Description

Technical Field

[0001] The present application relates to the field of LED driving technology, and in particular to an LED linear driving circuit and an LED device. Background Art

[0002] With the application of LED lighting in the global market, the current linear LED driving solution has the advantage of low cost. Most light sources and lamps below 10 watts use linear driving. Since the linear driving LED will only be lit when the input voltage is greater than the LED voltage. In response to the market requirements for 85-264Vac full voltage input, the current mainstream linear driving solution in the market requires the use of electrolytic capacitors. When high voltage is input, the electrolytic capacitors are used to divide the voltage to light up the LED. After the input voltage drops, the voltage on the electrolytic capacitor is released to the LED. Since the existing linear driving solution requires the use of electrolytic capacitors, the cost is relatively high and it is not convenient for full chip production. Utility Model Content

[0003] The purpose of the embodiments of the present application is to provide an LED linear drive circuit and an LED device to solve the problem that the existing linear drive solution requires electrolytic capacitors, resulting in high costs and difficulty in achieving full chip production.

[0004] An LED linear drive circuit provided in an embodiment of the present application includes a first constant current module, a second constant current module and a third constant current module;

[0005] The first end of the first constant current module is used to connect to the positive end of the external power supply, and the second end of the first constant current module is used to connect to the first end of the second LED load; the first end of the first constant current module is used to connect to the first end of the first LED load, the first end of the first diode is used to connect to the second end of the first LED load, and the second end of the first diode is used to connect to the first end of the second LED load; the first end of the second constant current module is used to connect to the second end of the first LED load, and the second end of the second constant current module is used to connect to the negative end of the external power supply; the first end of the third constant current module is used to connect to the second end of the second LED load, and the second end of the third constant current module is used to connect to the negative end of the external power supply;

[0006] The first constant current module is used to cut off the circuit when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, provide constant current power supply;

[0007] The second constant current module is used to cut off the circuit when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, it provides constant current power supply;

[0008] The third constant current module is used to provide constant current power supply when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, it works in the switch conduction mode.

[0009] In the above technical solution, the connection mode of the LED is automatically adjusted according to the size of the input voltage. When the input voltage is higher than the set voltage, the first constant current module and the second constant current module are disconnected, the first LED load and the second LED load are connected in series, and the third constant current module is used for constant current power supply; when the input voltage is lower than the set voltage, the third constant current module works in the switch conduction mode, the first constant current module supplies constant current to the second LED load, and the second constant current module supplies constant current to the first LED load. The LED linear drive circuit does not require electrolytic capacitors and can also meet the market demand for full voltage input of 85~264Vac. In addition, the circuit has a simple structure, small size, light weight, easy integration, and convenient full chip production.

[0010] In some optional implementations, the first constant current module and the second constant current module are both linear constant current sources with built-in linear compensation modules; and the third constant current module is a linear constant current source.

[0011] In the above technical solution, the first constant current module and the second constant current module have their own linear compensation. When the input voltage reaches the set voltage, the constant current source current of the first constant current module and the second constant current module drops to 0mA, and the first constant current module and the second constant current module respectively form a circuit break. For example, in this embodiment, the set voltage is 215V. In one half-wave, when the input voltage rises from 0 to 190V, the linear compensation module begins to intervene, and the current slowly decreases. When the input voltage reaches 215V, the linear compensation module reduces the constant current source current to 0mA.

[0012] In some optional implementations, the first constant current module is used to provide a constant current power supply of a first current when the input voltage is lower than a set voltage;

[0013] The second constant current module is used for providing a constant current power supply of a first current when the input voltage is lower than the set voltage;

[0014] The third constant current module is used to provide a constant current power supply of a second current when the input voltage is higher than the set voltage; wherein the second current is greater than the first current.

[0015] In the above technical solution, by setting the current of the third constant current module to be greater than the current of the first constant current module, when the input voltage is lower than the set voltage, the first constant current module and the third constant current module are on the same branch, the current of the branch reaches the current of the first constant current module and does not reach the current of the third constant current module, the third MOS tube in the third constant current module is turned on, and the first constant current module supplies power to the second LED load on the branch. When the input voltage is higher than the set voltage, the first LED load, the second LED load and the third constant current module are connected in series, and the third constant current module provides a constant current power supply of the second current.

[0016] In some optional embodiments, a comparator is further included;

[0017] The output end of the comparator is connected to the third end of the third constant current module;

[0018] The first input terminal of the comparator is connected to the positive terminal of the external power supply; the second input terminal of the comparator is connected to the reference voltage;

[0019] The comparator is used to output a high level signal to the third constant current module when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module when the input voltage is lower than the set voltage.

[0020] In the above technical solution, a comparator is used to compare the input voltage with the reference voltage, so that when the input voltage is higher than the set voltage, a high-level signal is output to the third constant current module to control the third constant current module to perform constant current power supply; when the input voltage is lower than the set voltage, a low-level signal is output to the third constant current module to control the third constant current module to operate in a switch conduction mode.

[0021] In some optional embodiments, a comparator is further included; the output end of the comparator is connected to the third end of the third constant current module; the first input end of the comparator is connected to the first end of the second constant current module; the second input end of the comparator is connected to the reference voltage;

[0022] The comparator is used to output a high level signal to the third constant current module when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module when the input voltage is lower than the set voltage.

[0023] In the above technical solution, a comparator is used to compare the voltage of the second constant current module with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high-level signal is output to the third constant current module to control the third constant current module to perform constant current power supply; when the input voltage is lower than the set voltage, a low-level signal is output to the third constant current module to control the third constant current module to operate in a switch conduction mode.

[0024] In some optional embodiments, a comparator is further included; the output end of the comparator is connected to the third end of the third constant current module; the first input end of the comparator is connected to the linear compensation module of the second constant current module; the second input end of the comparator is connected to the reference voltage;

[0025] The comparator is used to output a high level signal to the third constant current module when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module when the input voltage is lower than the set voltage.

[0026] In the above technical solution, a comparator is used to compare the linear compensation signal with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high-level signal is output to the third constant current module to control the third constant current module to perform constant current power supply; when the input voltage is lower than the set voltage, a low-level signal is output to the third constant current module to control the third constant current module to operate in a switch conduction mode.

[0027] In some optional implementations, the third constant current module includes: a switching module, a third operational amplifier and a third MOS tube;

[0028] The first end of the switching module is connected to the output end of the comparator, the second end of the switching module is connected to the positive input end of the third operational amplifier, the negative input end of the third operational amplifier is connected to the source of the third MOS tube, the output end of the third operational amplifier is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is connected to the negative end of the external power supply through the third resistor;

[0029] The switching module is used to connect the positive input terminal of the third operational amplifier to the first power supply according to a high-level signal received by the first end of the switching module; and to connect the positive input terminal of the third operational amplifier to the second power supply according to a low-level signal received by the first end of the switching module; wherein the voltage VREF2 of the second power supply is greater than the voltage VREF1 of the first power supply.

[0030] In the above technical solution, when the input voltage is lower than the set voltage, the current I2 of the second constant current module is VREF1 / R, the current flowing through the first LED load is VREF1 / R, the current I1 of the first constant current module is VREF1 / R, the current (I3=VREF2 / R) of the third constant current module is greater than the current of the first constant current module, the third constant current module operates in the switch conduction mode, and the current flowing through the first LED load is VREF1 / R; when the input voltage is higher than the set voltage, the first constant current module and the second constant current module are both open-circuited, and the current I3 of the third constant current module is VREF1 / R.

[0031] In some optional implementations, the third constant current module includes: a switching module, a third operational amplifier and a third MOS tube; the second constant current module includes a second operational amplifier and a second MOS tube;

[0032] The positive input terminal of the second operational amplifier is connected to the third power supply, the negative input terminal of the second operational amplifier is connected to the source of the second MOS tube, the output terminal of the second operational amplifier is connected to the gate of the second MOS tube, the drain of the second MOS tube is connected to the second end of the first LED load, and the source of the second MOS tube is also connected to the first end of the second resistor;

[0033] The first end of the switching module is connected to the output end of the comparator, the second end of the switching module is connected to the positive input end of the third operational amplifier, the negative input end of the third operational amplifier is connected to the source of the third MOS tube, the output end of the third operational amplifier is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is also connected to the first end of the second resistor; the second end of the second resistor is connected to the negative end of the external power supply;

[0034] The switching module is used to connect the positive input terminal of the third operational amplifier to the first power supply according to a high-level signal received by the first end of the switching module; and to connect the positive input terminal of the third operational amplifier to the fourth power supply according to a low-level signal received by the first end of the switching module; wherein the voltage of the first power supply is VREF1, the voltage of the third power supply VREF3 is equal to 2×VREF1, and the voltage of the fourth power supply VREF4 is greater than VREF3.

[0035] In the above technical solution, when the input voltage is higher than the set voltage, the current I3 of the third constant current module is VREF1 / R; when the input voltage is lower than the set voltage, the current I1 of the first constant current module is VREF1 / R, the current flowing through the second LED load is VREF1 / R, the second constant current module and the third constant current module share a sampling resistor, the current I flowing through the sampling resistor is 2×VREF1 / R, the current flowing through the first LED load is VREF1 / R, and the third constant current module operates in the switch conduction mode.

[0036] In some optional implementations, the third constant current module includes a third MOS tube and a third operational amplifier;

[0037] The positive input terminal of the third operational amplifier is connected to the first power supply, the negative input terminal of the third operational amplifier is connected to the source of the third MOS tube, the output terminal of the third operational amplifier is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is connected to the negative end of the external power supply through the third resistor;

[0038] The output end of the comparator is connected to the enable end of the third operational amplifier; when the comparator outputs a high-level signal to the enable end of the third operational amplifier, the third constant current module provides constant current power supply; when the comparator outputs a low-level signal to the enable end of the third operational amplifier, the third constant current module operates in a switch conduction mode.

[0039] In the above technical solution, when the input voltage is higher than the set voltage, the third constant current module provides constant current power supply, and the current I3 of the third constant current module is VREF1 / R; when the input voltage is lower than the set voltage, the first constant current module supplies power to the second LED load, and the current I1 of the first constant current module is VREF1 / R. The third constant current module operates in the switch conduction mode, and the second constant current module supplies power to the first LED load, and the current I2 of the second constant current module is VREF1 / R.

[0040] An LED device provided in an embodiment of the present application includes a first LED load, a second LED load, and an LED linear drive circuit as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of an LED linear drive circuit provided in an embodiment of the present application;

[0043] Figure 2 A structural diagram of an LED linear drive circuit provided in a specific embodiment of the present application;

[0044] Figure 3 A structural diagram of an LED linear drive circuit provided in the first embodiment of the present application;

[0045] Figure 4 A structural diagram of an LED linear drive circuit provided in the second embodiment of the present application;

[0046] Figure 5 A structural diagram of an LED linear drive circuit provided in the third embodiment of the present application;

[0047] Figure 6 A structural diagram of an LED linear drive circuit provided in the fourth embodiment of the present application;

[0048] Figure 7 A structural diagram of an LED linear drive circuit provided in the fifth embodiment of the present application;

[0049] Figure 8 A structural diagram of an LED linear drive circuit provided in the sixth embodiment of the present application;

[0050] Fig. 9 A structural diagram of an LED linear drive circuit provided in the seventh embodiment of the present application;

[0051] Fig.10 A structural diagram of an LED linear drive circuit provided in the eighth embodiment of the present application;

[0052] Fig.11 A structural diagram of an LED linear driving circuit provided in the ninth embodiment of the present application;

[0053] Fig.12 This is a structural diagram of an LED linear drive circuit provided in the tenth embodiment of the present application. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0055] Please refer to Figure 1 , Figure 1 A schematic diagram of an LED linear drive circuit provided in an embodiment of the present application includes a first constant current module SOURCE1, a second constant current module SOURCE2 and a third constant current module SOURCE3. Among them, the first end of the first constant current module SOURCE1 is used to connect to the positive end of an external power supply, and the second end of the first constant current module SOURCE1 is used to connect to the first end of a second LED load; the first end of the first constant current module SOURCE1 is used to connect to the first end of a first LED load, the first end of a first diode D1 is used to connect to the second end of the first LED load, and the second end of the first diode D1 is used to connect to the first end of a second LED load; the first end of the second constant current module SOURCE2 is used to connect to the second end of the first LED load, and the second end of the second constant current module SOURCE2 is used to connect to the negative end of an external power supply; the first end of the third constant current module SOURCE3 is used to connect to the second end of the second LED load, and the second end of the third constant current module SOURCE3 is used to connect to the negative end of an external power supply.

[0056] The first constant current module SOURCE1 is used to disconnect the circuit when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, it provides constant current power supply. The second constant current module SOURCE2 is used to disconnect the circuit when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, it provides constant current power supply. The third constant current module SOURCE3 is used to provide constant current power supply when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, it works in the switch conduction mode.

[0057] In the embodiment of the present application, the connection mode of the LED is automatically adjusted according to the size of the input voltage. When the input voltage is higher than the set voltage, the first constant current module SOURCE1 and the second constant current module SOURCE2 are disconnected, the first LED load and the second LED load are connected in series, and the constant current power supply is performed through the third constant current module SOURCE3; when the input voltage is lower than the set voltage, the third constant current module SOURCE3 works in the switch conduction mode, the first constant current module SOURCE1 provides constant current power supply for the second LED load, and the second constant current module SOURCE2 provides constant current power supply for the first LED load. The LED linear drive circuit does not require electrolytic capacitors and can also meet the market demand for full voltage input of 85~264Vac. In addition, the circuit has a simple structure, small size, light weight, easy integration, and convenient full chip production.

[0058] In some optional implementations, the first constant current module SOURCE1 and the second constant current module SOURCE2 are both linear constant current sources with built-in linear compensation modules; and the third constant current module SOURCE3 is a linear constant current source.

[0059] In the embodiment of the present application, the first constant current module SOURCE1 and the second constant current module SOURCE2 have their own linear compensation. When the input voltage reaches the set voltage, the constant current source current of the first constant current module SOURCE1 and the second constant current module SOURCE2 drops to 0mA, and the first constant current module SOURCE1 and the second constant current module SOURCE2 are open circuited. For example, in the present embodiment, the set voltage is 215V. In one half-wave, when the input voltage rises from 0 to 190V, the linear compensation module begins to intervene, and the current slowly decreases. When the input voltage reaches 215V, the linear compensation module reduces the constant current source current to 0mA.

[0060] Please refer to Figure 2 , Figure 2 This is a structural diagram of an LED linear drive circuit provided in a specific embodiment of the present application.

[0061] The first constant current module SOURCE1 includes a first linear compensation module LN1, a first MOS tube and a first operational amplifier OP1. The first constant current module SOURCE1 is used to provide a constant current power supply of current I=VREF1 / RCS1 when the input voltage is lower than the set voltage.

[0062] The second constant current module SOURCE2 includes a second linear compensation module LN2, a second MOS tube and a second operational amplifier OP2. The positive input terminal of the second operational amplifier OP2 of the second constant current module SOURCE2 is connected to the third power supply, and the voltage VREF3 of the third power supply is equal to 2×VREF1. The source of the second MOS tube is connected to the first end of the second resistor, and the second end of the second resistor is connected to the negative end of the external power supply.

[0063] The third constant current module SOURCE3 includes a switching module, a third MOS tube and a third operational amplifier OP3. The first end of the switching module is connected to the output end of the comparator COMP, the second end of the switching module is connected to the positive input end of the third operational amplifier OP3, the negative input end of the third operational amplifier OP3 is connected to the source of the third MOS tube, the output end of the third operational amplifier OP3 is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is also connected to the first end of the second resistor; the switching module is used to connect the positive input end of the third operational amplifier OP3 to the first power supply according to the high level signal received by the first end of the switching module; according to the low level signal received by the first end of the switching module, the positive input end of the third operational amplifier OP3 is connected to the fourth power supply; wherein the voltage VREF4 of the fourth power supply is greater than VREF3.

[0064] When the input voltage is higher than the set voltage, the comparator COMP outputs a high level to the third constant current module SOURCE3, so that the third constant current module SOURCE3 operates in a constant current source mode, and the current I3 of the third constant current module SOURCE3 is equal to VREF1 / R; when the input voltage is lower than the set voltage, the comparator outputs a low level to the third constant current module SOURCE3, so that the third constant current module SOURCE3 operates in a switch conduction mode, the current I1 of the first constant current module SOURCE1 is equal to VREF1 / R, and the current flowing through the second LED load is VREF1 / R. The second constant current module SOURCE2 and the third constant current module SOURCE3 share a sampling resistor RCS2, and the current flowing through the sampling resistor is I=2×VREF1 / R, and the current flowing through the first LED load is VREF1 / R.

[0065] Please refer to Figure 3 , Figure 3 This is a structural diagram of an LED linear drive circuit provided in the first embodiment of the present application. The sinusoidal input voltage of the external power supply reaches the LED linear drive circuit after passing through the rectifier module DB.

[0066] The first constant current module SOURCE1 includes a first linear compensation module LN1, a first MOS tube and a first operational amplifier OP1. The first constant current module SOURCE1 is used to provide a constant current power supply of current I=VREF1 / RCS1 when the input voltage is lower than the set voltage;

[0067] The second constant current module SOURCE2 includes a second linear compensation module LN2, a second MOS tube and a second operational amplifier OP2. The second constant current module SOURCE2 is used to provide a constant current power supply of current I=VREF1 / RCS2 when the input voltage is lower than the set voltage;

[0068] The third constant current module SOURCE3 includes a third linear compensation module, a third MOS tube and a third operational amplifier OP3. The third constant current module SOURCE3 is used to provide a constant current power supply of current I=VREF2 / RCS3 when the input voltage is higher than the set voltage; wherein the second current is greater than the first current, RCS1=RCS2=RCS3=R.

[0069] In the embodiment of the present application, by setting the current of the third constant current module SOURCE3 to be greater than the current of the first constant current module SOURCE1, when the input voltage is lower than the set voltage, the first constant current module SOURCE1 and the third constant current module SOURCE3 are on the same branch, the current of the branch reaches the current of the first constant current module SOURCE1 and does not reach the current of the third constant current module SOURCE3, the third MOS tube in the third constant current module SOURCE3 is turned on, and the first constant current module SOURCE1 supplies power to the second LED load on the branch. When the input voltage is higher than the set voltage, the first LED load, the second LED load and the third constant current module SOURCE3 are connected in series, and the third constant current module SOURCE3 provides a constant current power supply of the second current.

[0070] Please refer to Figure 4 , Figure 4 A structural diagram of an LED linear drive circuit provided for the second embodiment of the present application. The first constant current module SOURCE1 includes a first linear compensation module LN1, a first MOS tube and a first operational amplifier OP1. The first constant current module SOURCE1 is used to provide a constant current power supply of current I=VREF1 / RCS1 when the input voltage is lower than the set voltage; the second constant current module SOURCE2 includes a second linear compensation module LN2, a second MOS tube and a second operational amplifier OP2. The second constant current module SOURCE2 is used to provide a constant current power supply of current I=VREF1 / RCS2 when the input voltage is lower than the set voltage. RCS1=RCS2=RCS3=R.

[0071] The LED linear drive circuit of this embodiment also includes a comparator COMP; the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the linear compensation module of the second constant current module SOURCE2; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage.

[0072] In an embodiment of the present application, a comparator COMP is used to compare the linear compensation signal with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high-level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to perform constant current power supply; when the input voltage is lower than the set voltage, a low-level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to operate in a switch conduction mode.

[0073] The third constant current module SOURCE3 of this embodiment includes: a switch SW, a third operational amplifier OP3 and a third MOS tube; the control end of the switch SW is connected to the output end of the comparator COMP, the fixed end of the switch SW is connected to the positive input end of the third operational amplifier OP3, the negative input end of the third operational amplifier OP3 is connected to the source of the third MOS tube, the output end of the third operational amplifier OP3 is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is connected to the negative end of the external power supply through a third resistor; the first contact end of the switch SW is connected to the first power supply, and the second contact end of the switch SW is connected to the second power supply. The switch SW is used to connect the positive input end of the third operational amplifier OP3 to the first power supply according to the high level signal received by the control end thereof; and connect the positive input end of the third operational amplifier OP3 to the second power supply according to the low level signal received by the control end thereof; wherein the voltage VREF2 of the second power supply is greater than the voltage VREF1 of the first power supply.

[0074] In the embodiment of the present application, when the input voltage is lower than the set voltage, the current I2 of the second constant current module SOURCE2 is VREF1 / R, the current flowing through the first LED load is VREF1 / R, the current I1 of the first constant current module SOURCE1 is VREF1 / R, the current (I3=VREF2 / R) of the third constant current module SOURCE3 is greater than the current of the first constant current module SOURCE1, the third constant current module SOURCE3 operates in the switch conduction mode, and the current flowing through the first LED load is VREF1 / R; when the input voltage is higher than the set voltage, the first constant current module SOURCE1 and the second constant current module SOURCE2 are both open circuited, and the current I3 of the third constant current module SOURCE3 is VREF1 / R.

[0075] Please refer to Figure 5 , Figure 5A LED linear drive circuit structure diagram provided for the third embodiment of the present application is different from the second embodiment in that: in this embodiment, the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the positive end of the external power supply; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the input voltage with the reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0076] Please refer to Figure 6 , Figure 6 A LED linear drive circuit structure diagram provided for the fourth embodiment of the present application is different from the second embodiment in that: the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the first end of the second constant current module SOURCE2; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the voltage of the second constant current module SOURCE2 with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0077] Please refer to Figure 7 , Figure 7 The fifth embodiment of the present application provides a LED linear drive circuit structure diagram, which is different from the second embodiment in that:

[0078] The positive input terminal of the second operational amplifier OP2 of the second constant current module SOURCE2 is connected to the third power supply, and the voltage VREF3 of the third power supply is equal to 2×VREF1.

[0079] The control end of the switch SW is connected to the output end of the comparator COMP, the fixed end of the switch SW is connected to the positive input end of the third operational amplifier OP3, the negative input end of the third operational amplifier OP3 is connected to the source of the third MOS tube, the output end of the third operational amplifier OP3 is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is also connected to the first end of the second resistor; the second end of the second resistor is connected to the negative end of the external power supply; the first contact end of the switch SW is connected to the first power supply, and the second contact end of the switch SW is connected to the fourth power supply. The switch SW is used to connect the positive input end of the third operational amplifier OP3 to the first power supply according to the high level signal received by the control end thereof; and connect the positive input end of the third operational amplifier OP3 to the fourth power supply according to the low level signal received by the control end thereof; wherein the voltage VREF4 of the fourth power supply is greater than VREF3.

[0080] When the input voltage is higher than the set voltage, the current I3 of the third constant current module SOURCE3 is VREF1 / R; when the input voltage is lower than the set voltage, the current I1 of the first constant current module SOURCE1 is VREF1 / R, the current flowing through the second LED load is VREF1 / R, the second constant current module SOURCE2 and the third constant current module SOURCE3 share a sampling resistor RCS2, the current flowing through the sampling resistor is I=2×VREF1 / R, the current flowing through the first LED load is VREF1 / R, and the third constant current module SOURCE3 operates in the switch conduction mode.

[0081] Please refer to Figure 8 , Figure 8 A LED linear drive circuit structure diagram provided for the sixth embodiment of the present application is different from the fifth embodiment in that: in the present embodiment, the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the positive end of the external power supply; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the input voltage with the reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0082] Please refer to Fig. 9 , Fig. 9 A LED linear drive circuit structure diagram provided for the seventh embodiment of the present application is different from the fifth embodiment in that: the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the first end of the second constant current module SOURCE2; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the voltage of the second constant current module SOURCE2 with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0083] Please refer to Fig.10 , Fig.10A LED linear drive circuit structure diagram provided for the eighth embodiment of the present application is different from the second embodiment in that: the positive input terminal of the third operational amplifier OP3 is connected to the first power supply, the negative input terminal of the third operational amplifier OP3 is connected to the source of the third MOS tube, the output terminal of the third operational amplifier OP3 is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is connected to the negative end of the external power supply through the third resistor; the output terminal of the comparator COMP is connected to the enable terminal of the third operational amplifier OP3; when the comparator COMP outputs a high-level signal to the enable terminal of the third operational amplifier OP3, the third constant current module SOURCE3 provides constant current power supply; when the comparator COMP outputs a low-level signal to the enable terminal of the third operational amplifier OP3, the third constant current module SOURCE3 operates in a switch-on mode. The output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the first end of the second constant current module SOURCE2; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the voltage of the second constant current module SOURCE2 with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to perform constant current power supply; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0084] In the embodiment of the present application, when the input voltage is higher than the set voltage, the third constant current module SOURCE3 provides constant current power supply, and the current I3 of the third constant current module SOURCE3 is VREF1 / R; when the input voltage is lower than the set voltage, the first constant current module SOURCE1 supplies power to the second LED load, and the current I1 of the first constant current module SOURCE1 is VREF1 / R, the third constant current module SOURCE3 operates in the switch conduction mode, the second constant current module SOURCE2 supplies power to the first LED load, and the current I2 of the second constant current module SOURCE2 is VREF1 / R.

[0085] Please refer to Fig.11 , Fig.11A LED linear drive circuit structure diagram provided for the ninth embodiment of the present application is different from the eighth embodiment in that: the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the positive end of the external power supply; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the input voltage with the reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0086] Please refer to Fig.12 , Fig.12 A LED linear drive circuit structure diagram provided for the tenth embodiment of the present application is different from the eighth embodiment in that: the output end of the comparator COMP is connected to the third end of the third constant current module SOURCE3; the first input end of the comparator COMP is connected to the linear compensation module of the second constant current module SOURCE2; the second input end of the comparator COMP is connected to the reference voltage; the comparator COMP is used to output a high level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage. In the embodiment of the present application, the comparator COMP is used to compare the linear compensation signal with the corresponding reference voltage, so that when the input voltage is higher than the set voltage, a high level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to perform constant current power supply; when the input voltage is lower than the set voltage, a low level signal is output to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to work in the switch conduction mode.

[0087] The embodiment of the present application further provides an LED device, comprising a first LED load, a second LED load, and an LED linear drive circuit as described in any one of the above items.

[0088] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0089] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0090] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0091] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0092] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A LED linear drive circuit, characterized in that: It includes a first constant current module, a second constant current module and a third constant current module; The positive end of the external power supply, the first LED load, the first diode, the second LED load, the third constant current module and the negative end of the external power supply are connected in sequence; one end of the first constant current module is connected to the positive end of the first LED load, and the other end is connected to the positive end of the second LED load; one end of the second constant current module is connected to the negative end of the first LED load, and the other end is connected to the negative end of the external power supply; The first constant current module and the second constant current module are both used to disconnect when the input voltage is higher than the set voltage; and provide constant current power supply when the input voltage is lower than the set voltage; The third constant current module is used to provide constant current power supply when the input voltage is higher than the set voltage; and operate in a switch conduction mode when the input voltage is lower than the set voltage.

2. The LED linear driving circuit according to claim 1, characterized in that: The first constant current module and the second constant current module are both linear constant current sources with built-in linear compensation modules; the third constant current module is a linear constant current source.

3. The LED linear driving circuit according to claim 2, characterized in that: The first constant current module is used to provide a constant current power supply of a first current when the input voltage is lower than the set voltage; The second constant current module is used to provide a constant current power supply of a first current when the input voltage is lower than the set voltage; The third constant current module is used to provide a constant current power supply of a second current when the input voltage is higher than the set voltage; wherein the second current is greater than the first current.

4. The LED linear driving circuit according to claim 2, characterized in that: Also included is a comparator; The output end of the comparator is connected to the third end of the third constant current module; The first input terminal of the comparator is connected to the positive terminal of the external power supply; the second input terminal of the comparator is connected to the reference voltage; The comparator is used to output a high level signal to the third constant current module when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module when the input voltage is lower than the set voltage.

5. The LED linear driving circuit according to claim 2, characterized in that: Also included is a comparator; The output end of the comparator is connected to the third end of the third constant current module; the first input end of the comparator is connected to the first end of the second constant current module; the second input end of the comparator is connected to the reference voltage; The comparator is used to output a high level signal to the third constant current module when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module when the input voltage is lower than the set voltage.

6. The LED linear driving circuit according to claim 2, characterized in that: Also included is a comparator; The output end of the comparator is connected to the third end of the third constant current module; the first input end of the comparator is connected to the linear compensation module of the second constant current module; the second input end of the comparator is connected to the reference voltage; The comparator is used to output a high level signal to the third constant current module when the input voltage is higher than the set voltage; and output a low level signal to the third constant current module when the input voltage is lower than the set voltage.

7. The LED linear drive circuit according to any one of claims 4 to 6, characterized in that: The third constant current module includes: a switching module, a third operational amplifier and a third MOS tube; The first end of the switching module is connected to the output end of the comparator, the second end of the switching module is connected to the positive input end of the third operational amplifier, the negative input end of the third operational amplifier is connected to the source of the third MOS tube, the output end of the third operational amplifier is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is connected to the negative end of the external power supply through a third resistor; The switching module is used to connect the positive input terminal of the third operational amplifier to the first power supply according to a high-level signal received at the first end of the switching module; and to connect the positive input terminal of the third operational amplifier to the second power supply according to a low-level signal received at the first end of the switching module; wherein the voltage VREF2 of the second power supply is greater than the voltage VREF1 of the first power supply.

8. The LED linear drive circuit according to any one of claims 4 to 6, characterized in that: The third constant current module includes: a switching module, a third operational amplifier and a third MOS tube; the second constant current module includes a second operational amplifier and a second MOS tube; The positive input terminal of the second operational amplifier is connected to the third power supply, the negative input terminal of the second operational amplifier is connected to the source of the second MOS tube, the output terminal of the second operational amplifier is connected to the gate of the second MOS tube, the drain of the second MOS tube is connected to the second end of the first LED load, and the source of the second MOS tube is also connected to the first end of the second resistor; The first end of the switching module is connected to the output end of the comparator, the second end of the switching module is connected to the positive input end of the third operational amplifier, the negative input end of the third operational amplifier is connected to the source of the third MOS tube, the output end of the third operational amplifier is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is also connected to the first end of the second resistor; the second end of the second resistor is connected to the negative end of the external power supply; The switching module is used to connect the positive input terminal of the third operational amplifier to the first power supply according to a high-level signal received by the first end of the switching module; and to connect the positive input terminal of the third operational amplifier to the fourth power supply according to a low-level signal received by the first end of the switching module; wherein the voltage of the first power supply is VREF1, the voltage of the third power supply VREF3 is equal to 2×VREF1, and the voltage of the fourth power supply VREF4 is greater than VREF3.

9. The LED linear drive circuit according to any one of claims 4 to 6, characterized in that: The third constant current module includes a third MOS tube and a third operational amplifier; The positive input terminal of the third operational amplifier is connected to the first power supply, the negative input terminal of the third operational amplifier is connected to the source of the third MOS tube, the output terminal of the third operational amplifier is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second end of the second LED load, and the source of the third MOS tube is connected to the negative end of the external power supply through the third resistor; The output end of the comparator is connected to the enable end of the third operational amplifier; when the comparator outputs a high-level signal to the enable end of the third operational amplifier, the third constant current module provides constant current power supply; when the comparator outputs a low-level signal to the enable end of the third operational amplifier, the third constant current module operates in a switch conduction mode.

10. An LED device, characterized in that: The invention comprises a first LED load, a second LED load and the LED linear driving circuit as claimed in any one of claims 1 to 9.

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