LED linear driving circuit

Abstract

The invention provides an LED linear driving circuit. The LED linear driving circuit comprises a switching module, a first constant current source module and a second constant current source module. The connection mode of the LED modules is automatically adjusted according to the magnitude of input voltage, when the input voltage is higher than set voltage, the first LED module and the second LED module are connected in series for voltage division, and constant-current power supply is carried out through the second constant-current source module; when the input voltage is lower than the set voltage, the first LED module and the second LED module are connected in parallel, the first constant-current source module supplies power to the first LED module in a constant-current mode, and the second constant-current source module supplies power to the second LED module 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. 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. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide an LED linear drive circuit 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 by an embodiment of the present application includes: a switching module, a first constant current source module and a second constant current source module;

[0005] The switching module is used to control the first LED module, the second LED module and the second constant current source module to form a series circuit when the input voltage is higher than the set voltage; and to control the first branch and the second branch to form a parallel circuit when the input voltage is lower than the set voltage; wherein the first branch includes the first LED module and the first constant current source module connected in series; and the second branch includes the second LED module and the second constant current source module connected in series;

[0006] The first constant current source module is used to supply constant current to the first LED module when the input voltage is lower than the set voltage; when the input voltage is higher than the set voltage, disconnect the connection between the negative end of the first LED module and the negative end of the external power supply;

[0007] The second constant current source module is used to supply constant current to the second LED module when the input voltage is lower than the set voltage; and to supply constant current to the first LED module and the second LED module connected in series when the input voltage is higher than the set voltage.

[0008] In the above technical solution, the connection mode of the LED module is automatically adjusted according to the size of the input voltage. When the input voltage is higher than the set voltage, the first LED module and the second LED module are connected in series to divide the voltage, and the constant current power supply is performed through the second constant current source module; when the input voltage is lower than the set voltage, the first LED module and the second LED module are connected in parallel, the first constant current source module supplies constant current to the first LED module, and the second constant current source module supplies constant current to the second LED module. 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.

[0009] In some optional embodiments, the first end of the switching module is connected to the positive end of the external power supply, the positive end of the external power supply is also connected to the positive end of the first LED module, the negative end of the first LED module is connected to the positive end of the first diode, the negative end of the first diode is connected to the positive end of the second LED module, the negative end of the second LED module is connected to the negative end of the external power supply through the second constant current source module, the second end of the switching module is connected to the positive end of the second LED module, and the negative end of the first LED module is connected to the negative end of the external power supply through the first constant current source module.

[0010] In the above technical solution, when the switching module is disconnected and the first constant current source module is disconnected, the positive end of the external power supply, the first LED module, the first diode, the second LED module, the second constant current source module and the negative end of the external power supply form a working circuit, and the first LED module and the second LED module are connected in series for voltage division. When the switching module is turned on and the first constant current source module is turned on, the positive end of the external power supply, the first LED module, the first constant current source module and the negative end of the external power supply form a working circuit, and the positive end of the external power supply, the switching module, the second LED module, the second constant current module and the negative end of the external power supply also form a working circuit, and at this time, the first LED module and the second LED module are connected in parallel.

[0011] In some optional implementations, the switching module includes: a control logic circuit and a first MOS tube;

[0012] The drain of the first MOS tube is connected to the positive end of the external power supply, the source of the first MOS tube is connected to the positive end of the second LED module, the gate of the first MOS tube is connected to the first end of the control logic circuit, and the second end of the control logic circuit is connected to the positive end of the first diode.

[0013] In the above technical solution, the switching module includes a control logic circuit and a first MOS tube. The first MOS tube serves as a switching device. The control logic circuit controls the first MOS tube to be turned on when the input voltage is less than the set voltage, and to be turned off when the input voltage is greater than the set voltage.

[0014] In some optional implementations, the control logic circuit includes: a second MOS tube, a second diode, a seventh resistor, an eighth resistor and a ninth resistor;

[0015] The first end of the seventh resistor is connected to the drain of the first MOS tube, the second end of the seventh resistor is connected to the gate of the first MOS tube, the second end of the seventh resistor is connected to the drain of the second MOS tube, the source of the second MOS tube is connected to the positive end of the second LED module, the source of the second MOS tube is connected to the positive end of the second diode, the negative end of the second diode is connected to the gate of the second MOS tube, the gate of the second MOS tube is connected to the first power supply, and the gate of the second MOS tube is connected to the positive end of the first diode.

[0016] In the above technical solution, the gate of the second MOS tube is connected to the input end of the first constant current source module. When the input voltage is less than the set voltage, the first constant current source module is turned on, the input end of the first constant current source module is at a low level, the gate of the second MOS tube is pulled down to a low level by the eighth resistor, the second MOS tube is disconnected, the gate of the first MOS tube is pulled up to a high level by the seventh resistor, and the first MOS tube is turned on. When the input voltage is greater than the set voltage, the first constant current source module is disconnected, the gate of the second MOS tube is pulled up to a high level by the ninth resistor, the second MOS tube is turned on, the gate of the first MOS tube is pulled down to a low level by the second MOS tube, and the first MOS tube is disconnected.

[0017] In some optional implementations, the control logic circuit includes: a second comparator, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourteenth resistor;

[0018] The positive end of the first diode is connected to the first end of the eleventh resistor, the second end of the eleventh resistor is connected to the first end of the twelfth resistor, the second end of the twelfth resistor is connected to the second power supply, the second power supply is connected to the first end of the thirteenth resistor, the second end of the thirteenth resistor is connected to the first end of the fourteenth resistor, the second end of the fourteenth resistor is grounded, the second end of the eleventh resistor is connected to the negative input end of the second comparator, the second end of the thirteenth resistor is connected to the positive input end of the second comparator, and the output end of the second comparator is connected to the gate of the first MOS tube.

[0019] In the above technical solution, the thirteenth resistor and the fourteenth resistor form a second voltage-dividing resistor, and the second voltage after the second power supply voltage is divided by the second voltage-dividing resistor is input to the positive input terminal of the second comparator. When the input voltage is less than the set voltage, the first constant current source module is turned on, the eleventh resistor and the twelfth resistor form a first voltage-dividing resistor, the first voltage after the first voltage-dividing resistor is input to the negative input terminal of the second comparator, the first voltage is less than the second voltage, and the second comparator outputs a high level to the first MOS tube, so that the first MOS tube is turned on. When the input voltage is higher than the set voltage, the first constant current source module is disconnected, the second power supply voltage is input to the negative input terminal of the second comparator, the second power supply voltage is greater than the second voltage, and the output terminal of the second comparator outputs a low level to the gate of the first MOS tube, so that the first MOS tube is disconnected.

[0020] In some optional implementations, the first constant current source module includes: an enabling control circuit, a first constant current source chip and a first sampling resistor;

[0021] The input end of the enable control circuit is connected to the positive end of the external power supply, the output end of the enable control circuit is connected to the enable end of the first constant current source chip, the input end of the first constant current source chip is connected to the positive end of the first diode, the output end of the first constant current source chip is connected to the first end of the first sampling resistor, and the second end of the first sampling resistor is connected to the negative end of the external power supply.

[0022] In the above technical solution, the first constant current source module includes an enable control circuit, a first constant current source chip and a first sampling resistor. The enable control circuit controls the first constant current source chip to provide constant current power when the input voltage is less than the set voltage. The enable control circuit also controls the first constant current source chip to disconnect when the input voltage is greater than the set voltage.

[0023] In some optional embodiments, the enabling control circuit includes a first comparator;

[0024] The negative input terminal of the first comparator is connected to the positive terminal of the external power supply, the positive input terminal of the first comparator is used to input a set voltage, and the output terminal of the first comparator is connected to the enable terminal of the first constant current source chip.

[0025] In some optional implementations, the first constant current source chip includes: a first operational amplifier and a third MOS tube;

[0026] The positive input terminal of the first operational amplifier is used to input a set voltage, the negative input terminal of the first operational amplifier is connected to the source of the third MOS tube, the source of the third MOS tube is connected to the first end of the first sampling resistor, the drain of the third MOS tube is connected to the input terminal of the first diode, and the output terminal of the first operational amplifier is connected to the gate of the third MOS tube.

[0027] In the above technical solution, the control logic circuit is used to output a low-level signal or a high-level signal to the first MOS tube for control. The signal transmission line of the control logic circuit is grounded after passing through the third MOS tube, and there is no need to set a high-voltage MOS tube separately for the signal transmission line.

[0028] In some optional implementations, the second constant current source module includes: a second constant current source chip and a second sampling resistor;

[0029] The input end of the second constant current source chip is connected to the output end of the second LED module, the output end of the second constant current source chip is connected to the first end of the second sampling resistor, and the second end of the second sampling resistor is connected to the negative end of the external power supply.

[0030] In some optional implementations, the second constant current source chip includes: a second operational amplifier and a fourth MOS tube;

[0031] The positive input terminal of the second operational amplifier is used to input a set voltage, the negative input terminal of the second operational amplifier is connected to the source of the fourth MOS tube, the source of the fourth MOS tube is connected to the first end of the second sampling resistor, the drain of the fourth MOS tube is connected to the input terminal of the second LED module, and the output terminal of the second operational amplifier is connected to the gate of the fourth MOS tube.

[0032] In the above technical solution, the first constant current source chip and the second constant current driver chip are both linear constant current driver chips including an operational amplifier and a MOS tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] 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.

[0034] Figure 1 A functional module diagram of an LED linear drive circuit provided in an embodiment of the present application;

[0035] Figure 2 A structural diagram of an LED linear drive circuit provided in an embodiment of the present application;

[0036] Figure 3 A structural diagram of an LED linear driving circuit provided in the first embodiment of the present application;

[0037] Figure 4 A structural diagram of an LED linear drive circuit provided in the second embodiment of the present application;

[0038] Figure 5This is a structural diagram of an LED linear drive circuit provided in the third embodiment of the present application. DETAILED DESCRIPTION

[0039] 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.

[0040] Please refer to Figure 1 , Figure 1 This is a functional module diagram of an LED linear drive circuit provided in an embodiment of the present application. The LED linear drive circuit specifically includes: a switching module, a first constant current source module and a second constant current source module.

[0041] The switching module is used to control the first LED module, the second LED module and the second constant current source module to form a series circuit when the input voltage is higher than the set voltage; and to control the first branch and the second branch to form a parallel circuit when the input voltage is lower than the set voltage; wherein the first branch includes the first LED module and the first constant current source module connected in series; and the second branch includes the second LED module and the second constant current source module connected in series. The first constant current source module is used to supply constant current to the first LED module when the input voltage is lower than the set voltage; and disconnect the connection between the negative end of the first LED module and the negative end of the external power supply when the input voltage is higher than the set voltage. The second constant current source module is used to supply constant current to the second LED module when the input voltage is lower than the set voltage; and supply constant current to the first LED module and the second LED module connected in series when the input voltage is higher than the set voltage.

[0042] Specifically, the switching module can be connected to an external power supply to detect changes in the input voltage, and the first constant current source module is also connected to the external power supply to detect changes in the input voltage. Alternatively, the switching module is connected to an external power supply to detect changes in the input voltage, and the first constant current source module is connected to the switching module. When the switching module detects changes in the input voltage and switches, the first constant current source module also switches. Alternatively, the first constant current source module is connected to an external power supply to detect changes in the input voltage, and the switching module is connected to the first constant current source module. When the first constant current source module detects changes in the input voltage and switches, the switching module also switches.

[0043] In the embodiment of the present application, the connection mode of the LED module is automatically adjusted according to the size of the input voltage. When the input voltage is higher than the set voltage, the first LED module and the second LED module are connected in series to divide the voltage, and the constant current power supply is performed through the second constant current source module; when the input voltage is lower than the set voltage, the first LED module and the second LED module are connected in parallel, the first constant current source module supplies constant current to the first LED module, and the second constant current source module supplies constant current to the second LED module. 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.

[0044] In some optional implementations, please refer to Figure 2 , Figure 2 A structural diagram of an LED linear drive circuit is provided in an embodiment of the present application, wherein the first end of the switching module is connected to the positive end of an external power supply, the positive end of the external power supply is also connected to the positive end of a first LED module, the negative end of the first LED module is connected to the positive end of a first diode, the negative end of the first diode is connected to the positive end of a second LED module, the negative end of the second LED module is connected to the negative end of the external power supply through a second constant current source module, the second end of the switching module is connected to the positive end of the second LED module, and the negative end of the first LED module is connected to the negative end of the external power supply through the first constant current source module.

[0045] In the embodiment of the present application, when the switching module is disconnected and the first constant current source module is disconnected, the positive end of the external power supply, the first LED module, the first diode, the second LED module, the second constant current source module and the negative end of the external power supply form a working loop, and the first LED module and the second LED module are connected in series for voltage division. When the switching module is turned on and the first constant current source module is turned on, the positive end of the external power supply, the first LED module, the first constant current source module and the negative end of the external power supply form a working loop, and the positive end of the external power supply, the switching module, the second LED module, the second constant current module and the negative end of the external power supply also form a working loop, and at this time, the first LED module and the second LED module are connected in parallel.

[0046] 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 switching module includes: a control logic circuit and a first MOS tube; the drain of the first MOS tube is connected to the positive end of the external power supply, the source of the first MOS tube is connected to the positive end of the second LED module, the gate of the first MOS tube is connected to the first end of the control logic circuit, and the second end of the control logic circuit is connected to the positive end of the first diode.

[0047] In an embodiment of the present application, the switching module includes a control logic circuit and a first MOS tube. The first MOS tube serves as a switching device. The control logic circuit controls the first MOS tube to be turned on when the input voltage is less than a set voltage, and to be turned off when the input voltage is greater than the set voltage.

[0048] In some optional embodiments, the first constant current source module includes: an enable control circuit, a first constant current source chip and a first sampling resistor; the input end of the enable control circuit is connected to the positive end of the external power supply, the output end of the enable control circuit is connected to the enable end of the first constant current source chip, the input end of the first constant current source chip is connected to the positive end of the first diode, the output end of the first constant current source chip is connected to the first end of the first sampling resistor, and the second end of the first sampling resistor is connected to the negative end of the external power supply.

[0049] In an embodiment of the present application, the first constant current source module includes an enable control circuit, a first constant current source chip and a first sampling resistor. The enable control circuit controls the first constant current source chip to provide constant current supply when the input voltage is less than a set voltage. The enable control circuit also controls the first constant current source chip to disconnect when the input voltage is greater than the set voltage.

[0050] In some optional embodiments, the enable control circuit includes a first comparator; the negative input terminal of the first comparator is connected to the positive terminal of the external power supply, the positive input terminal of the first comparator is used to input a set voltage, and the output terminal of the first comparator is connected to the enable terminal of the first constant current source chip.

[0051] In some optional embodiments, the first constant current source chip includes: a first operational amplifier and a third MOS tube; the positive input terminal of the first operational amplifier is used to input a set voltage, the negative input terminal of the first operational amplifier is connected to the source of the third MOS tube, the source of the third MOS tube is connected to the first end of the first sampling resistor, the drain of the third MOS tube is connected to the input terminal of the first diode, and the output terminal of the first operational amplifier is connected to the gate of the third MOS tube.

[0052] In this embodiment, the control logic circuit is used to output a low level signal or a high level signal to the first MOS tube for control. The signal transmission line of the control logic circuit is grounded after passing through the third MOS tube, and there is no need to set a high-voltage MOS tube separately for the signal transmission line.

[0053] In some optional embodiments, the second constant current source module includes: a second constant current source chip and a second sampling resistor; the input end of the second constant current source chip is connected to the output end of the second LED module, the output end of the second constant current source chip is connected to the first end of the second sampling resistor, and the second end of the second sampling resistor is connected to the negative end of the external power supply.

[0054] In some optional embodiments, the second constant current source chip includes: a second operational amplifier and a fourth MOS tube; the positive input terminal of the second operational amplifier is used to input a set voltage, the negative input terminal of the second operational amplifier is connected to the source of the fourth MOS tube, the source of the fourth MOS tube is connected to the first end of the second sampling resistor, the drain of the fourth MOS tube is connected to the input terminal of the second LED module, and the output terminal of the second operational amplifier is connected to the gate of the fourth MOS tube.

[0055] In the embodiment of the present application, the first constant current source chip and the second constant current driver chip are both linear constant current driver chips including an operational amplifier and a MOS tube.

[0056] Please refer to Figure 4 , Figure 4 This is a diagram of the LED linear drive circuit structure provided for the second embodiment of the present application. In the figure, LED1-LED8 is the first LED module, LED9-LED16 is the second LED module, and the external power supply is input to the positive end of the first LED module after being rectified by the rectifier bridge DB1, and the negative end of the first LED module returns to the negative output end of the rectifier bridge DB1 after passing through the constant current source chip U2 and the resistor R10. The first LED module is connected to the positive end of the diode D1, and the negative end of the diode D1 is connected to the positive end of the second LED module. The negative end of the second LED module returns to the negative output end of the rectifier bridge DB1 after passing through the constant current source chip U3 and the resistor R11, and the negative output end of the rectifier bridge DB1 is grounded. The drain of the MOS tube Q1 is connected to the positive output end of the rectifier bridge DB1, the source of the MOS tube Q1 is connected to the positive end of the second LED module, and the gate of the MOS tube Q1 is connected to the control logic circuit.

[0057] The control logic circuit of this embodiment includes: a MOS tube Q2, a diode D2, a resistor R7, a resistor R8 and a resistor R9; a first end of the resistor R7 is connected to the drain of the MOS tube Q1, a second end of the resistor R7 is connected to the gate of the MOS tube Q1, a second end of the resistor R7 is connected to the drain of the MOS tube Q2, a source of the MOS tube Q2 is connected to the positive end of the second LED module, a source of the MOS tube Q2 is connected to the positive end of the diode D2, a negative end of the diode D2 is connected to the gate of the MOS tube Q2, a gate of the MOS tube Q2 is connected to a power supply VCC, and a gate of the MOS tube Q2 is connected to the positive end of the diode D1.

[0058] In the embodiment of the present application, the gate of the MOS transistor Q2 is connected to the OUT terminal of the constant current source chip U2. When the input voltage is less than the set voltage, the constant current source chip U2 is turned on, the OUT terminal of the constant current source chip U2 is at a low level, the gate of the MOS transistor Q2 is pulled down to a low level by the resistor R8, the MOS transistor Q2 is disconnected, the gate of the MOS transistor Q1 is pulled up to a high level by the resistor R7, and the MOS transistor Q1 is turned on. When the input voltage is greater than the set voltage, the constant current source chip U2 is disconnected, the gate of the MOS transistor Q2 is pulled up to a high level by the resistor R9, the MOS transistor Q2 is turned on, the gate of the MOS transistor Q1 is pulled down to a low level by the MOS transistor Q2, and the MOS transistor Q1 is disconnected.

[0059] The positive output end of the rectifier bridge DB1 is also connected to the ground after being connected to the resistor R1, the resistor R2 and the resistor R3 in sequence. The resistor R1, the resistor R2 and the resistor R3 form a voltage-dividing resistor, and the input voltage is sampled and input to the negative input end of the comparator U1. The power supply VDD is connected to the ground after passing through the resistor R4 and the resistor R5 in sequence. The resistor R4 and the resistor R5 form a voltage-dividing resistor, and the output end of the resistor R4 is connected to the positive input end of the comparator U1. By setting the resistance values ​​of the resistors R1, R2, R3, R4 and R5, the input voltage is compared with the set voltage, and the high level or low level output by the comparator U1 is used to enable the constant current source chip U2.

[0060] The negative input terminal of the comparator U1 is also connected to the ground through the capacitor C2, and the capacitor C2 is used for filtering and voltage stabilization. The comparator U1 is also enabled by the power supply VDD, and the power supply VDD is also connected to the ground through the capacitor C1, and the capacitor C1 is used for filtering and voltage stabilization. The power supply VDD is also connected to the output terminal of the comparator U1 through the resistor R6.

[0061] Please refer to Figure 5 , Figure 5This is a diagram of the LED linear drive circuit structure provided in the third embodiment of the present application. In the figure, LED1-LED8 is the first LED module, LED9-LED16 is the second LED module, and the external power supply is input to the positive end of the first LED module after being rectified by the rectifier bridge DB1, and the negative end of the first LED module returns to the negative output end of the rectifier bridge DB1 after passing through the constant current source chip U2 and the resistor R17. The first LED module is connected to the positive end of the diode D1, and the negative end of the diode D1 is connected to the positive end of the second LED module. The negative end of the second LED module returns to the negative output end of the rectifier bridge DB1 after passing through the constant current source chip U4 and the resistor R19, and the negative output end of the rectifier bridge DB1 is grounded. The drain of the MOS tube Q1 is connected to the positive output end of the rectifier bridge DB1, the source of the MOS tube Q1 is connected to the positive end of the second LED module, and the gate of the MOS tube Q1 is connected to the control logic circuit. The positive output end of the rectifier bridge DB1 is also connected to the ground after connecting to the resistor R1, the resistor R2 and the resistor R3 in sequence. The resistor R1, the resistor R2 and the resistor R3 form a voltage-dividing resistor, and the input voltage is sampled and input to the negative input end of the comparator U1. The power supply VDD is connected to the ground after passing through the resistor R4 and the resistor R5 in sequence. The resistor R4 and the resistor R5 form a voltage-dividing resistor, and the output end of the resistor R4 is connected to the positive input end of the comparator U1. By setting the resistance values ​​of the resistors R1, R2, R3, R4 and R5, the input voltage is compared with the set voltage, and the high level or low level output by the comparator U1 is used to enable the constant current source chip U2. The negative input end of the comparator U1 is also connected to the ground after passing through the capacitor C2, and the capacitor C2 is used for filtering and voltage stabilization. The comparator U1 is also enabled by a 5V power supply, and the 5V power supply is also grounded after passing through the capacitor C1, and the capacitor C1 is used for filtering and voltage stabilization. The 5V power supply is also connected to the output end of the comparator U1 after passing through the resistor R6.

[0062] The control logic circuit of this embodiment includes: a comparator U3, a resistor R11, a resistor R12, a resistor R13 and a resistor R14; the positive end of the diode D1 is connected to the first end of the resistor R11, the second end of the resistor R11 is connected to the first end of the resistor R12, the second end of the resistor R12 is connected to a 5V power supply, the 5V power supply is connected to the first end of the resistor R13, the second end of the resistor R13 is connected to the first end of the resistor R14, the second end of the resistor R14 is connected to the signal ground, the second end of the resistor R11 is connected to the negative input end of the comparator U3, the second end of the resistor R13 is connected to the positive input end of the comparator U3, and the output end of the comparator U3 is connected to the gate of the first MOS tube.

[0063] In the embodiment of the present application, the resistor R13 and the resistor R14 form a second voltage-dividing resistor, and the positive input terminal of the comparator U3 inputs the second voltage after the 5V power supply voltage is divided by the second voltage-dividing resistor. When the input voltage is less than the set voltage, the first constant current source module is turned on, the resistor R11 and the resistor R12 form a first voltage-dividing resistor, the negative input terminal of the comparator U3 inputs the first voltage after the first voltage-dividing resistor is divided, the first voltage is less than the second voltage, and the comparator U3 outputs a high level to the first MOS tube, so that the first MOS tube is turned on. When the input voltage is higher than the set voltage, the first constant current source module is disconnected, the negative input terminal of the comparator U3 inputs the 5V power supply voltage, the 5V power supply voltage is greater than the second voltage, and the output terminal of the comparator U3 outputs a low level to the gate of the first MOS tube, so that the first MOS tube is disconnected.

[0064] The 5V power supply is also connected to the ground through the capacitor CS, and the capacitor CS is used for filtering and voltage stabilization. The negative input terminal of the comparator U3 is also connected to the signal ground through the capacitor C4, and the capacitor C4 is used for filtering and voltage stabilization. The negative input terminal of the comparator U3 is also connected to the negative terminal of the diode D2, and the positive terminal of the diode D2 is connected to the signal ground. The negative terminal of the diode D1 is connected to the signal ground. The 5V power supply is connected to the output terminal of the comparator U3 through the resistor R15, and the output terminal of the comparator U3 is connected to the negative terminal of the diode Dz through the resistor RJ, and the positive terminal of the diode Dz is connected to the signal ground. The negative terminal of the diode Dz is also connected to the gate of the MOS tube Q1, and the gate of the MOS tube Q1 is connected to the drain of the MOS tube Q1 through the resistor R16.

[0065] 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.

[0066] 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.

[0067] 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 independently, or two or more modules may be integrated to form an independent part.

[0068] 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.

[0069] 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: include: A switching module, a first constant current source module and a second constant current source module; The switching module is used to control the first LED module, the second LED module and the second constant current source module to form a series circuit when the input voltage is higher than the set voltage; and to control the first branch and the second branch to form a parallel circuit when the input voltage is lower than the set voltage; wherein the first branch includes the first LED module and the first constant current source module connected in series; and the second branch includes the second LED module and the second constant current source module connected in series; The first constant current source module is used to supply constant current to the first LED module when the input voltage is lower than the set voltage; when the input voltage is higher than the set voltage, disconnect the connection between the negative end of the first LED module and the negative end of the external power supply; The second constant current source module is used to supply constant current to the second LED module when the input voltage is lower than the set voltage; and to supply constant current to the first LED module and the second LED module connected in series when the input voltage is higher than the set voltage.

2. The circuit according to claim 1, characterized in that The first end of the switching module is connected to the positive end of the external power supply, the positive end of the external power supply is also connected to the positive end of the first LED module, the negative end of the first LED module is connected to the positive end of the first diode, the negative end of the first diode is connected to the positive end of the second LED module, the negative end of the second LED module is connected to the negative end of the external power supply through the second constant current source module, the second end of the switching module is connected to the positive end of the second LED module, and the negative end of the first LED module is connected to the negative end of the external power supply through the first constant current source module.

3. The circuit according to claim 2, characterized in that The switching module comprises: a control logic circuit and a first MOS tube; The drain of the first MOS tube is connected to the positive end of the external power supply, the source of the first MOS tube is connected to the positive end of the second LED module, the gate of the first MOS tube is connected to the first end of the control logic circuit, and the second end of the control logic circuit is connected to the positive end of the first diode.

4. The circuit according to claim 3, characterized in that The control logic circuit includes: a second MOS tube, a second diode, a seventh resistor, an eighth resistor and a ninth resistor; The first end of the seventh resistor is connected to the drain of the first MOS tube, the second end of the seventh resistor is connected to the gate of the first MOS tube, the second end of the seventh resistor is connected to the drain of the second MOS tube, the source of the second MOS tube is connected to the positive end of the second LED module, the source of the second MOS tube is connected to the positive end of the second diode, the negative end of the second diode is connected to the gate of the second MOS tube, the gate of the second MOS tube is connected to the first power supply, and the gate of the second MOS tube is connected to the positive end of the first diode.

5. The circuit according to claim 3, characterized in that The control logic circuit comprises: a second comparator, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor; The positive end of the first diode is connected to the first end of the eleventh resistor, the second end of the eleventh resistor is connected to the first end of the twelfth resistor, the second end of the twelfth resistor is connected to the second power supply, the second power supply is connected to the first end of the thirteenth resistor, the second end of the thirteenth resistor is connected to the first end of the fourteenth resistor, the second end of the fourteenth resistor is grounded, the second end of the eleventh resistor is connected to the negative input end of the second comparator, the second end of the thirteenth resistor is connected to the positive input end of the second comparator, and the output end of the second comparator is connected to the gate of the first MOS tube.

6. The circuit according to claim 2, characterized in that The first constant current source module comprises: an enabling control circuit, a first constant current source chip and a first sampling resistor; The input end of the enable control circuit is connected to the positive end of the external power supply, the output end of the enable control circuit is connected to the enable end of the first constant current source chip, the input end of the first constant current source chip is connected to the positive end of the first diode, the output end of the first constant current source chip is connected to the first end of the first sampling resistor, and the second end of the first sampling resistor is connected to the negative end of the external power supply.

7. The circuit according to claim 6, characterized in that The enabling control circuit comprises a first comparator; The negative input terminal of the first comparator is connected to the positive terminal of the external power supply, the positive input terminal of the first comparator is used to input a set voltage, and the output terminal of the first comparator is connected to the enable terminal of the first constant current source chip.

8. The circuit according to claim 6, characterized in that The first constant current source chip comprises: a first operational amplifier and a third MOS tube; The positive input terminal of the first operational amplifier is used to input a set voltage, the negative input terminal of the first operational amplifier is connected to the source of the third MOS tube, the source of the third MOS tube is connected to the first end of the first sampling resistor, the drain of the third MOS tube is connected to the input terminal of the first diode, and the output terminal of the first operational amplifier is connected to the gate of the third MOS tube.

9. The circuit according to claim 1, characterized in that The second constant current source module comprises: a second constant current source chip and a second sampling resistor; The input end of the second constant current source chip is connected to the output end of the second LED module, the output end of the second constant current source chip is connected to the first end of the second sampling resistor, and the second end of the second sampling resistor is connected to the negative end of the external power supply.

10. The circuit according to claim 9, characterized in that The second constant current source chip comprises: a second operational amplifier and a fourth MOS tube; The positive input terminal of the second operational amplifier is used to input a set voltage, the negative input terminal of the second operational amplifier is connected to the source of the fourth MOS tube, the source of the fourth MOS tube is connected to the first end of the second sampling resistor, the drain of the fourth MOS tube is connected to the input terminal of the second LED module, and the output terminal of the second operational amplifier is connected to the gate of the fourth MOS tube.

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