LED linear driving circuit and LED device

Abstract

The invention 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] This application relates to the technical field of LED driving, and more particularly, to an LED linear driving circuit and an LED device. Background Art

[0002] With the application of the global LED lighting market, the current linear LED driving scheme has the advantage of low cost. For light sources and lamps below 10 watts, most of them adopt linear driving. Since the LED will only be lit when the input voltage is greater than the LED voltage in linear driving. For the market requirement of 85 - 264Vac full voltage input, the current mainstream linear driving scheme in the market needs to use electrolytic capacitors. When the high voltage is input, the electrolytic capacitor is used for voltage division to light the LED. After the input voltage drops, the voltage on the electrolytic capacitor is released to the LED. Since the existing linear driving scheme needs to use electrolytic capacitors, the cost is relatively high and it is not convenient for full-chip production. Summary of the Invention

[0003] The purpose of the embodiments of this application is to provide an LED linear driving circuit and an LED device to solve the problem that the existing linear driving scheme needs electrolytic capacitors, resulting in relatively high costs and difficulty in realizing full-chip production.

[0004] An LED linear driving circuit provided by the embodiments of this 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 the positive terminal of the external power supply, and the second end of the first constant current module is used to connect the first end of the second LED load; the first end of the first constant current module is used to connect the first end of the first LED load, the first end of the first diode is used to connect the second end of the first LED load, and the second end of the first diode is used to connect the first end of the second LED load; the first end of the second constant current module is used to connect the second end of the first LED load, and the second end of the second constant current module is used to connect the negative terminal of the external power supply; the first end of the third constant current module is used to connect the second end of the second LED load, and the second end of the third constant current module is used to connect the negative terminal of the external power supply;

[0006] The first constant current module is used to open the circuit 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;

[0007] The second constant current module is used to open the circuit 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;

[0008] 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 the switch conduction mode when the input voltage is lower than the set voltage.

[0009] In the above technical solution, the connection mode of the LED is automatically adjusted according to the magnitude 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 open-circuited, and the first LED load and the second LED load are connected in series, and constant current power supply is performed through the third constant current module. When the input voltage is lower than the set voltage, the third constant current module operates in the switch conduction mode, the first constant current module performs constant current power supply for the second LED load, and the second constant current module performs 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 85-264 Vac. Moreover, the circuit structure is simple, the volume is small, the weight is light, it is easy to integrate, and it is convenient for full patch production.

[0010] In some optional embodiments, both the first constant current module and the second constant current module are linear constant current sources with built-in linear compensation modules; 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 built-in linear compensation. When the input voltage reaches the set voltage, the constant current source currents of the first constant current module and the second constant current module drop to 0 mA, and the first constant current module and the second constant current module respectively form open circuits. For example, in this embodiment, the set voltage is 215V. In a half-wave, when the input voltage rises from 0 to 190V, the linear compensation module starts to intervene and the current slowly decreases. When the input voltage reaches 215V, the linear compensation module suppresses the constant current source current to 0 mA.

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

[0013] The second constant current module is used to provide 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 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 this 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 conducts, and the first constant current module supplies power to the second LED load on this 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 constant current power supply of the second current.

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

[0017] The output terminal of the comparator is connected to the third terminal 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, the comparator is used to compare the input voltage with the reference voltage, so as to output a high-level signal to the third constant current module when the input voltage is higher than the set voltage, controlling the third constant current module to perform constant current power supply; and output a low-level signal to the third constant current module when the input voltage is lower than the set voltage, controlling the third constant current module to operate in the switch conduction mode.

[0021] In some alternative embodiments, a comparator is further included; the output terminal of the comparator is connected to the third terminal of the third constant current module; the first input terminal of the comparator is connected to the first terminal of the second constant current module; the second input terminal 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, the comparator is used to compare the voltage of the second constant current module with the corresponding reference voltage, so as to output a high-level signal to the third constant current module when the input voltage is higher than the set voltage, controlling the third constant current module to perform constant current power supply; and output a low-level signal to the third constant current module when the input voltage is lower than the set voltage, controlling the third constant current module to operate in the switch conduction mode.

[0024] In some alternative embodiments, a comparator is further included; the output terminal of the comparator is connected to the third terminal of the third constant current module; the first input terminal of the comparator is connected to the linear compensation module of the second constant current module; the second input terminal 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. Thus, 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 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 to control the third constant current module to operate in the switch-on mode.

[0027] In some alternative embodiments, the third constant current module includes: a switching module, a third operational amplifier, and a third MOS transistor;

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

[0029] The switching module is configured to connect the positive input terminal of the third operational amplifier to the first power supply according to the high-level signal received at the first terminal of the switching module; and connect the positive input terminal of the third operational amplifier to the second power supply according to the low-level signal received at the first terminal 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 I2 = VREF1 / R, the current flowing through the first LED load is VREF1 / R, the current I1 of the first constant current module is I1 = VREF1 / R, the current of the third constant current module (I3 = VREF2 / R) is greater than the current of the first constant current module, the third constant current module operates in the switch-on mode, and the current flowing through the first LED load is VREF1 / R; when the input voltage is higher than the set voltage, both the first constant current module and the second constant current module are open circuits, and the current I3 of the third constant current module is I3 = VREF1 / R.

[0031] In some alternative embodiments, the third constant current module includes: a switching module, a third operational amplifier, and a third MOS transistor; the second constant current module includes a second operational amplifier and a second MOS transistor;

[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 electrode of the second MOS transistor, the output terminal of the second operational amplifier is connected to the gate electrode of the second MOS transistor, the drain electrode of the second MOS transistor is connected to the second terminal of the first LED load, and the source electrode of the second MOS transistor is further connected to the first terminal of a 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 electrode of the third MOS transistor. The output end of the third operational amplifier is connected to the gate electrode of the third MOS transistor. The drain electrode of the third MOS transistor is connected to the second end of the second LED load. The source electrode of the third MOS transistor is also connected to the first end of the second resistor. The second end of the second resistor is connected to the negative terminal of the external power supply.

[0034] The switching module is configured to connect the positive input end of the third operational amplifier to the first power supply according to the high-level signal received at the first end of the switching module, and connect the positive input end of the third operational amplifier to the fourth power supply according to the low-level signal received at the first end of the switching module. Wherein, the voltage of the first power supply is VREF1, the voltage VREF3 of the third power supply is equal to 2×VREF1, and the voltage VREF4 of the fourth power supply 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 I3 = VREF1 / R; when the input voltage is lower than the set voltage, the current I1 of the first constant-current module is I1 = 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 I = 2×VREF1 / R, the current flowing through the first LED load is VREF1 / R, and the third constant-current module operates in the switch-on mode.

[0036] In some alternative embodiments, the third constant-current module includes a third MOS transistor and a third operational amplifier.

[0037] The positive input end of the third operational amplifier is connected to the first power supply. The negative input end of the third operational amplifier is connected to the source electrode of the third MOS transistor. The output end of the third operational amplifier is connected to the gate electrode of the third MOS transistor. The drain electrode of the third MOS transistor is connected to the second end of the second LED load. The source electrode of the third MOS transistor is connected to the negative terminal of the external power supply after passing 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 the switch-on 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 = VREF1 / R; when the input voltage is lower than the set voltage, the first constant current module supplies power to the second LED load, the current I1 of the first constant current module = VREF1 / R, the third constant current module operates in the switch-on mode, the second constant current module supplies power to the first LED load, and the current I2 of the second constant current module = VREF1 / R.

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

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0042] Figure 1 Schematic diagram of an LED linear drive circuit provided by an embodiment of the present application;

[0043] Figure 2 Structural diagram of the LED linear drive circuit provided by a specific embodiment of the present application;

[0044] Figure 3 Structural diagram of an LED linear drive circuit provided by the first embodiment of the present application;

[0045] Figure 4 Structural diagram of an LED linear drive circuit provided by the second embodiment of the present application;

[0046] Figure 5 Structural diagram of an LED linear drive circuit provided by the third embodiment of the present application;

[0047] Figure 6 Structural diagram of an LED linear drive circuit provided by the fourth embodiment of the present application;

[0048] Figure 7 Structural diagram of an LED linear drive circuit provided by the fifth embodiment of the present application;

[0049] Figure 8 Structural diagram of an LED linear drive circuit provided by the sixth embodiment of the present application;

[0050] Figure 9 Structural diagram of an LED linear drive circuit provided by the seventh embodiment of the present application;

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

[0052] Figure 11 A structural diagram of an LED linear drive circuit provided for the ninth embodiment of the present application;

[0053] Figure 12 A structural diagram of an LED linear drive circuit provided for the tenth embodiment of the present application. Detailed implementation manners

[0054] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application.

[0055] Please refer to Figure 1 , Figure 1 , which is a schematic diagram of an LED linear drive circuit provided for an embodiment of the present application, including 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 terminal of the external power supply, and the second end of the first constant current module SOURCE1 is used to connect to the first end of the second LED load; the first end of the first constant current module SOURCE1 is used to connect to the first end of the first LED load, the first end of the 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 the 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 terminal of the 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 terminal of the external power supply.

[0056] The first constant current module SOURCE1 is used to open 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 open 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 operates in the switch conduction mode.

[0057] In the embodiments of the present application, the connection mode of the LED is automatically adjusted according to the magnitude 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 open-circuited, and the first LED load and the second LED load are connected in series, and 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 operates in the switch-on mode, the first constant current module SOURCE1 performs constant current power supply for the second LED load, and the second constant current module SOURCE2 performs 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 85-264 Vac. Moreover, the circuit structure is simple, the volume is small, the weight is light, it is easy to integrate, and it is convenient for full chip production.

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

[0059] In the embodiments of the present application, the first constant current module SOURCE1 and the second constant current module SOURCE2 have built-in linear compensation. When the input voltage reaches the set voltage, the constant current of the constant current sources of the first constant current module SOURCE1 and the second constant current module SOURCE2 drops to 0 mA, and the first constant current module SOURCE1 and the second constant current module SOURCE2 respectively form open circuits. For example, in this embodiment, the set voltage is 215V. In a half-wave, when the input voltage rises from 0 to 190V, the linear compensation module starts to intervene and the current slowly decreases. When the input voltage reaches 215V, the linear compensation module reduces the constant current source current to 0 mA.

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

[0061] Among them, the first constant current module SOURCE1 includes a first linear compensation module LN1, a first MOS transistor, and a first operational amplifier OP1. The first constant current module SOURCE1 is used to provide constant current power supply with a 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 transistor, 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 electrode of the second MOS transistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the negative terminal of the external power supply.

[0063] The third constant current module SOURCE3 includes a switching module, a third MOS transistor, 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 electrode of the third MOS transistor, the output end of the third operational amplifier OP3 is connected to the gate electrode of the third MOS transistor, the drain electrode of the third MOS transistor is connected to the second end of the second LED load, and the source electrode of the third MOS transistor is also connected to the first end of the second resistor; the switching module is configured to connect the positive input end of the third operational amplifier OP3 to the first power supply according to the high-level signal received at the first end of the switching module; and connect the positive input end of the third operational amplifier OP3 to the fourth power supply according to the low-level signal received at the first end of the switching module; 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, causing the third constant current module SOURCE3 to operate in the constant current source mode, and the current I3 of the third constant current module SOURCE3 = 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, causing the third constant current module SOURCE3 to operate in the switch conduction mode, the current I1 of the first constant current module SOURCE1 = 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 I flowing through the sampling resistor = 2×VREF1 / R, and the current flowing through the first LED load is VREF1 / R.

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

[0066] The first constant current module SOURCE1 includes a first linear compensation module LN1, a first MOS transistor, and a first operational amplifier OP1. The first constant current module SOURCE1 is configured to provide a constant current power supply with a current I = VREF1 / RCS1 in the case where 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 transistor, and a second operational amplifier OP2. The second constant current module SOURCE2 is configured to provide a constant current power supply with a current I = VREF1 / RCS2 in the case where 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 transistor, and a third operational amplifier OP3. The third constant current module SOURCE3 is used to provide a constant current supply with a current I = VREF2 / RCS3 when the input voltage is higher than the set voltage; among them, the second current is greater than the first current, and 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 this 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 transistor in the third constant current module SOURCE3 conducts, and the first constant current module SOURCE1 supplies power to the second LED load on this 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 supply with the second current.

[0070] Please refer to Figure 4 , Figure 4 which is a structural diagram of an LED linear drive circuit provided by the second embodiment of the present application. The first constant current module SOURCE1 includes a first linear compensation module LN1, a first MOS transistor, and a first operational amplifier OP1. The first constant current module SOURCE1 is used to provide a constant current supply with a 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 transistor, and a second operational amplifier OP2. The second constant current module SOURCE2 is used to provide a constant current supply with a 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 further 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 the embodiment of the present application, a comparator COMP is used to compare the linear compensation signal with the corresponding reference voltage. Thus, 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 the 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 transistor; 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 electrode of the third MOS transistor, the output end of the third operational amplifier OP3 is connected to the gate electrode of the third MOS transistor, the drain electrode of the third MOS transistor is connected to the second end of the second LED load, and the source electrode of the third MOS transistor is connected to the negative terminal of the external power supply after passing through the third resistor; the first contact end of the switch SW is connected to the first power supply, the second contact end of the switch SW is connected to the second power supply, and 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 its control end; 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 its control end; 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 = VREF1 / R, the current flowing through the first LED load is VREF1 / R, the current I1 of the first constant current module SOURCE1 = VREF1 / R, the current of the third constant current module SOURCE3 (I3 = VREF2 / R) 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, both the first constant current module SOURCE1 and the second constant current module SOURCE2 are open circuits, and the current I3 of the third constant current module SOURCE3 = VREF1 / R.

[0075] Please refer to Figure 5 , Figure 5A structural diagram of an LED linear drive circuit provided by the third embodiment of the present application is different from that of the second embodiment in that: in this embodiment, the output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the positive terminal of the external power supply; the second input terminal 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 as to output a high-level signal to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current when the input voltage is higher than the set voltage; and output a low-level signal to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to operate in the switch conduction mode when the input voltage is lower than the set voltage.

[0076] Please refer to Figure 6 , Figure 6 A structural diagram of an LED linear drive circuit provided by the fourth embodiment of the present application is different from that of the second embodiment in that: the output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the first terminal of the second constant current module SOURCE2; the second input terminal 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 as to output a high-level signal to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to supply constant current when the input voltage is higher than the set voltage; and output a low-level signal to the third constant current module SOURCE3 to control the third constant current module SOURCE3 to operate in the switch conduction mode when the input voltage is lower than the set voltage.

[0077] Please refer to Figure 7 , Figure 7 A structural diagram of an LED linear drive circuit provided by the fifth embodiment of the present application is different from that of 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 terminal of the switch SW is connected to the output terminal of the comparator COMP. The fixed terminal of the switch SW is connected to the positive input terminal of the third operational amplifier OP3. The negative input terminal of the third operational amplifier OP3 is connected to the source electrode of the third MOS transistor. The output terminal of the third operational amplifier OP3 is connected to the gate electrode of the third MOS transistor. The drain electrode of the third MOS transistor is connected to the second terminal of the second LED load. The source electrode of the third MOS transistor is also connected to the first terminal of the second resistor. The second terminal of the second resistor is connected to the negative terminal of the external power supply. The first contact terminal of the switch SW is connected to the first power supply. The second contact terminal of the switch SW is connected to the fourth power supply. The switch SW is configured to connect the positive input terminal of the third operational amplifier OP3 to the first power supply according to the high-level signal received by its control terminal, and to connect the positive input terminal of the third operational amplifier OP3 to the fourth power supply according to the low-level signal received by its control terminal, where 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 I3 = VREF1 / R. When the input voltage is lower than the set voltage, the current I1 of the first constant current module SOURCE1 is I1 = 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 I flowing through this 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 FIG. is a structural diagram of an LED linear drive circuit provided in the sixth embodiment of the present application. The difference from the fifth embodiment is that: in this embodiment, the output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the positive terminal of the external power supply; the second input terminal of the comparator COMP is connected to the reference voltage. The comparator COMP is configured to output a high-level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage, and to 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 as to output a high-level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage to control the third constant current module SOURCE3 to perform constant current power supply; and to output a low-level signal to the third constant current module SOURCE3 when the input voltage is lower than the set voltage to control the third constant current module SOURCE3 to operate in the switch conduction mode.

[0082] Please refer toFigure 9 , Figure 9 This is a structural diagram of an LED linear drive circuit provided by the seventh embodiment of the present application. The difference from the fifth embodiment is that the output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the first terminal of the second constant current module SOURCE2; the second input terminal of the comparator COMP is connected to a 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 as to output a high-level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage, and control the third constant current module SOURCE3 to perform constant current power supply; when the input voltage is lower than the set voltage, output a low-level signal to the third constant current module SOURCE3, and control the third constant current module SOURCE3 to work in the switch conduction mode.

[0083] Please refer to Figure 10 , Figure 10A structural diagram of an LED linear drive circuit provided by the eighth embodiment of the present application, which 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 electrode of the third MOS transistor, the output terminal of the third operational amplifier OP3 is connected to the gate electrode of the third MOS transistor, the drain electrode of the third MOS transistor is connected to the second end of the second LED load, and the source electrode of the third MOS transistor is connected to the negative terminal of the external power supply after passing 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 the switch conduction mode. The output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the first terminal of the second constant current module SOURCE2; the second input terminal 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 as to output a high-level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage, and control the third constant current module SOURCE3 to provide constant current power supply; when the input voltage is lower than the set voltage, output a low-level signal to the third constant current module SOURCE3, and control the third constant current module SOURCE3 to operate 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 = 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, the current I1 of the first constant current module SOURCE1 = VREF1 / R, the third constant current module SOURCE3 operates in the switch conduction mode, and the second constant current module SOURCE2 supplies power to the first LED load, and the current I2 of the second constant current module SOURCE2 = VREF1 / R.

[0085] Please refer to Figure 11 , Figure 11A structural diagram of an LED linear drive circuit provided for the ninth embodiment of the present application. The difference from the eighth embodiment is that the output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the positive terminal of the external power supply; the second input terminal 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 as to output a high-level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage, and control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, output a low-level signal to the third constant current module SOURCE3, and control the third constant current module SOURCE3 to operate in the switch-on mode.

[0086] Please refer to Figure 12 , Figure 12 A structural diagram of an LED linear drive circuit provided for the tenth embodiment of the present application. The difference from the eighth embodiment is that the output terminal of the comparator COMP is connected to the third terminal of the third constant current module SOURCE3; the first input terminal of the comparator COMP is connected to the linear compensation module of the second constant current module SOURCE2; the second input terminal 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 as to output a high-level signal to the third constant current module SOURCE3 when the input voltage is higher than the set voltage, and control the third constant current module SOURCE3 to supply constant current; when the input voltage is lower than the set voltage, output a low-level signal to the third constant current module SOURCE3, and control the third constant current module SOURCE3 to operate in the switch-on mode.

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

[0088] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For another 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 displayed or discussed couplings or direct couplings or communication connections between each other can be through some communication interfaces. The indirect couplings or communication connections 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. The components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0090] Furthermore, in each embodiment of this application, the various functional modules can be integrated together to form an independent part, or each module can exist alone, or two or more modules can be integrated to form an independent part.

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

[0092] The above are only the embodiments of this application and are not used to limit the protection scope of this application. For those skilled in the art, this application can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

1. An 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 terminal of the external power supply, the first LED load, the first diode, the second LED load, the third constant current source module and the negative terminal of the external power supply are connected in sequence; one end of the first constant current module is connected to the positive terminal of the first LED load, and the other end is connected to the positive terminal of the second LED load; one end of the second constant current module is connected to the negative terminal of the first LED load, and the other end is connected to the negative terminal of the external power supply; Both the first constant current module and the second constant current module are used to open the circuit when the input voltage is higher than the set voltage; when the input voltage is lower than the set voltage, they provide constant current power supply; 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 operates in the switch conduction mode.

2. The LED linear drive circuit according to claim 1, characterized in that Both the first constant current module and the second constant current module are 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, wherein The first constant current module is used to provide constant current power supply with a first current when the input voltage is lower than the set voltage; The second constant current module is used to provide constant current power supply with a first current when the input voltage is lower than the set voltage; The third constant current module is used to provide constant current power supply with a second current when the input voltage is higher than the set voltage; where the second current is greater than the first current.

4. The LED linear driving circuit according to claim 2, wherein It also includes a comparator; The output terminal of the comparator is connected to the third terminal 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; when the input voltage is lower than the set voltage, it outputs a low-level signal to the third constant current module.

5. The LED linear driving circuit according to claim 2, wherein It also includes a comparator; The output terminal of the comparator is connected to the third terminal of the third constant current module; the first input terminal of the comparator is connected to the first terminal of the second constant current module; 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; when the input voltage is lower than the set voltage, it outputs a low-level signal to the third constant current module.

6. The LED linear driving circuit according to claim 2, wherein, It also includes a comparator; The output terminal of the comparator is connected to the third terminal of the third constant current module; the first input terminal of the comparator is connected to the linear compensation module of the second constant current module; 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; when the input voltage is lower than the set voltage, it outputs a low-level signal to the third constant current module.

7. The LED linear drive circuit according to any one of claims 4-6, characterized in that, The third constant current module includes: a switching module, a third operational amplifier and a third MOS transistor; 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 electrode of the third MOS transistor. The output end of the third operational amplifier is connected to the gate electrode of the third MOS transistor. The drain electrode of the third MOS transistor is connected to the second end of the second LED load. The source electrode of the third MOS transistor is connected to the negative terminal of the external power supply after passing through a third resistor. The switching module is configured to connect the positive input end of the third operational amplifier to a first power supply according to a high-level signal received at the first end of the switching module, and connect the positive input end of the third operational amplifier to a 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 4-6, characterized in that The third constant current module includes a switching module, a third operational amplifier, and a third MOS transistor. The second constant current module includes a second operational amplifier and a second MOS transistor. The positive input end of the second operational amplifier is connected to a third power supply. The negative input end of the second operational amplifier is connected to the source electrode of the second MOS transistor. The output end of the second operational amplifier is connected to the gate electrode of the second MOS transistor. The drain electrode of the second MOS transistor is connected to the second end of the first LED load. The source electrode of the second MOS transistor is further connected to the first end of a 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 electrode of the third MOS transistor. The output end of the third operational amplifier is connected to the gate electrode of the third MOS transistor. The drain electrode of the third MOS transistor is connected to the second end of the second LED load. The source electrode of the third MOS transistor is further connected to the first end of the second resistor. The second end of the second resistor is connected to the negative terminal of the external power supply. The switching module is configured to connect the positive input end of the third operational amplifier to a first power supply according to a high-level signal received at the first end of the switching module, and connect the positive input end of the third operational amplifier to a fourth power supply according to a low-level signal received at the first end of the switching module. Wherein, the voltage of the first power supply is VREF1, the voltage VREF3 of the third power supply is equal to 2×VREF1, and the voltage VREF4 of the fourth power supply is greater than VREF3.

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

10. An LED device, characterized in that, It includes a first LED load, a second LED load, and the LED linear drive circuit according to any one of claims 1-9.

Images