LED constant current control circuit

Abstract

The invention provides an LED constant-current control circuit. The LED constant-current control circuit comprises a discharge control module, a constant-current control module, a first capacitor and a one-way conduction module, the input current of the external power supply is input into the first capacitor through the one-way conduction module to charge the first capacitor. And the input current or the first capacitor current discharged by the first capacitor is input to the load through the constant current control module, so that the stroboflash-free constant current power supply of the load is realized. The discharge control module allows the first capacitor to discharge and supply power to the load when the input voltage is lower than the set value, and prevents the first capacitor from discharging when the input voltage is higher than the set value, and in the process, the phase angle width of the input current within an input voltage half wave is increased by setting the lower set value, and the PF value is increased.

Description

Technical Field

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

[0002] LED light source is a light source based on light-emitting diodes, which has the advantages of using low-voltage power supply, low energy consumption, strong applicability, high stability, short response time, no pollution to the environment, and multi-color light emission. With the continuous development of LED technology, the performance requirements for LED drivers are getting higher and higher. For example, the new European standard requires different PF values ​​for different powers. For power 5-25W, PF>0.7 is required, and for power greater than 25W, PF>0.9 is required. However, the existing LED drive circuit is difficult to meet the requirements of high PF values. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide an LED constant current control circuit to solve the problem that the existing LED driving circuit is difficult to meet the requirements of high PF value.

[0004] An LED constant current control circuit provided by an embodiment of the present application includes: a discharge control module, a constant current control module, a first capacitor and a unidirectional conduction module;

[0005] The unidirectional conduction module is used to allow the input current to pass through the unidirectional conduction module to reach the positive end of the first capacitor, so as to charge the first capacitor;

[0006] The discharge control module is connected to the first capacitor. The discharge control module is used to allow the first capacitor to discharge when the input voltage is lower than the set value. The first capacitor current discharged by the first capacitor passes through the discharge control module and the constant current control module to reach the load to supply power to the load; when the input voltage is higher than the set value, the first capacitor is prevented from discharging;

[0007] The constant current control module is connected to the load, and is used to convert the input current or the first capacitor current into a constant current to provide constant current power supply to the load.

[0008] In the above technical solution, the input current of the external power supply is input into the first capacitor through the unidirectional conduction module to charge the first capacitor. The input current or the first capacitor current discharged by the first capacitor is input to the load through the constant current control module to realize flicker-free constant current power supply of the load. By using the discharge control module, when the input voltage is lower than the set value, the first capacitor is allowed to discharge and supply power to the load, and when the input voltage is higher than the set value, the first capacitor is prevented from discharging. In this process, by setting a lower set value, the phase angle width of the input current within an input voltage half wave is increased, thereby improving the PF value.

[0009] In some optional implementations, the discharge control module includes: a discharge control logic circuit, a first MOS tube and a first resistor;

[0010] The output end of the discharge control logic circuit is connected to the gate of the first MOS tube. The discharge control logic circuit is used to judge whether the input voltage is higher than the set value according to the voltage of the first resistor. When the input voltage is higher than the set value, the low level signal is output to the first MOS tube to turn off the first MOS tube; when the input voltage is lower than the set value, the high level signal is output to the first MOS tube to turn on the first MOS tube. In addition, due to the existence of the unidirectional conduction module, the first MOS tube can use a low-voltage MOS tube.

[0011] In the above technical solution, the on-off of the first capacitor discharge circuit is realized by using the on-off of the first MOS tube, the first resistor is used to obtain a sampling voltage that is positively correlated with the input voltage, and the discharge control logic circuit outputs a low-level signal or a high-level signal according to the size of the sampling voltage, thereby controlling the on-off of the first MOS tube, and when the first MOS tube is turned on, the first capacitor is discharged with a constant current, and the input current drops to 0.

[0012] In some optional embodiments, the first end of the discharge control logic circuit is connected to the first end of the first resistor, the second end of the first resistor is connected to the source of the first MOS tube, and the drain of the first MOS tube is connected to the positive end of the first capacitor.

[0013] In some optional embodiments, the discharge control logic circuit includes a first comparator; the positive input terminal of the first comparator is used to input a first reference voltage, the negative input terminal of the first comparator is connected to the source of the first MOS tube, the output terminal of the first comparator is connected to the gate of the first MOS tube, the first end of the first resistor is connected to the source of the first MOS tube, and the second end of the first resistor is connected to the positive end of the load.

[0014] In the above technical solution, the discharge control logic circuit adopts a first comparator to output a low-level signal or a high-level signal according to the size of the sampling voltage. In this embodiment, a first reference voltage is input to the positive input end of the first comparator, and a voltage of a first resistor is input to the negative input end of the first comparator. The voltage of the first resistor is positively correlated with the input voltage. When the first reference voltage is greater than the voltage of the first resistor, that is, when the input voltage is lower than a set value, the first comparator outputs a high-level signal to the first MOS tube, so that the first MOS tube is turned on, and the first capacitor can be discharged to the load through the first MOS tube; when the first reference voltage is less than the voltage of the first resistor, that is, when the input voltage is higher than the set value, the first comparator outputs a low-level signal to the first MOS tube, so that the first MOS tube is turned off, and the discharge loop of the first capacitor is disconnected.

[0015] In some optional embodiments, the first end of the discharge control logic circuit is connected to the first end of the first resistor, the second end of the first resistor is connected to the drain of the first MOS tube, the source of the first MOS tube is connected to the negative end of the first capacitor, and the second end of the first resistor is also connected to the negative end of the load.

[0016] In some optional embodiments, the discharge control logic circuit includes a first comparator; the positive input terminal of the first comparator is used to input a first reference voltage, the negative input terminal of the first comparator is connected to the source of the first MOS tube, the output terminal of the first comparator is connected to the gate of the first MOS tube, the first end of the first resistor is connected to the source of the first MOS tube, and the second end of the first resistor is used to connect to the negative end of an external power supply.

[0017] In the above technical solution, the discharge control logic circuit adopts a first comparator to output a low-level signal or a high-level signal according to the size of the sampling voltage. In this embodiment, a first reference voltage is input to the positive input end of the first comparator, and a voltage of a first resistor is input to the negative input end of the first comparator. The voltage of the first resistor is positively correlated with the input voltage. When the first reference voltage is greater than the voltage of the first resistor, that is, when the input voltage is lower than a set value, the first comparator outputs a high-level signal to the first MOS tube, so that the first MOS tube is turned on, and the first capacitor can be discharged to the load through the first MOS tube; when the first reference voltage is less than the voltage of the first resistor, that is, when the input voltage is higher than the set value, the first comparator outputs a low-level signal to the first MOS tube, so that the first MOS tube is turned off, and the discharge loop of the first capacitor is disconnected.

[0018] In some optional implementations, the constant current control module includes: a second comparator, a second MOS tube and a sampling resistor;

[0019] The positive end of the second comparator is used to input the second reference voltage, the negative end of the second comparator is connected to the source of the second MOS tube, the source of the second MOS tube is connected to the sampling resistor, and the output end of the second comparator is connected to the gate of the second MOS tube.

[0020] In the above technical solution, the constant current control module adopts a constant current source circuit composed of a second comparator, a second MOS tube and a sampling resistor.

[0021] In this embodiment, a constant current source including a first MOS tube and a first resistor is used in the discharge control module, and the first capacitor, the first MOS tube, the second MOS tube and the load form a capacitor discharge loop. The resistance value of the first resistor is greater than the resistance value of the sampling resistor, so that when the voltages of the two constant current sources fluctuate within the compliance range, the current harmonic components can be controlled within a smaller range.

[0022] In some optional embodiments, the constant current control module includes a DCDC module;

[0023] The positive terminal of the load is also connected to the negative terminal of the external power supply through a second capacitor.

[0024] In the above technical solution, the constant current control module adopts a switch constant current DCDC module. A second capacitor is set between the positive end of the load and the negative end of the external power supply. The second capacitor is connected in parallel with the first capacitor to increase the capacitance and extend the service life of the overall circuit.

[0025] In some optional embodiments, the unidirectional conduction module includes a body diode of the first MOS tube, an input end of the body diode is connected to the source of the first MOS tube, and an output end of the body diode is connected to the drain of the first MOS tube.

[0026] In the above technical solution, the unidirectional conduction module directly adopts the body diode of the first MOS tube, which reduces the number of diode devices and reduces the cost.

[0027] In some optional embodiments, it also includes: a rectifier module; the rectifier module is used to connect to an external power supply; the unidirectional conduction module also includes a first diode and a second diode; the input end of the first diode is connected to the positive input end of the rectifier module, the input end of the second diode is connected to the negative input end of the rectifier module, and the output ends of the first diode and the second diode are both connected to the first capacitor.

[0028] In the above technical solution, it is taken into consideration that the circuit often generates very high operating overvoltage when struck by lightning and when connecting or disconnecting an inductive load or a large load. This instantaneous overvoltage (or overcurrent) is called a surge voltage (or surge current), which is a transient interference. Therefore, in this embodiment, a first diode and a second diode are provided to cope with the surge voltage.

[0029] In some optional implementations, the discharge control module includes: an adaptive current detection circuit, a first MOS tube and a drive circuit;

[0030] The output end of the adaptive current detection circuit is connected to the input end of the driving circuit, and the output end of the driving circuit is connected to the gate of the first MOS tube. The adaptive current detection circuit is used to detect the input current and control the driving circuit to output a high-level signal to the first MOS tube when the input current starts to decrease, so that the first MOS tube is turned on; when the input current starts to rise, the driving circuit is controlled to output a low-level signal to the first MOS tube, so that the first MOS tube is turned off.

[0031] In the above technical solution, when the input voltage is higher than the set value, the input current starts to increase from 0, and when the input voltage is lower than the set value, the input current starts to decrease to 0. Therefore, this embodiment detects the input current through the adaptive current detection circuit and outputs a high level or low level signal to control the on and off of the first MOS tube, and can also achieve that when the input voltage is lower than the set value, the first capacitor is allowed to discharge and supply power to the load, and when the input voltage is higher than the set value, the first capacitor is prevented from discharging.

[0032] In some optional implementations, the adaptive current detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first comparator, and a peak current sampling and holding module;

[0033] The first end of the first resistor is used to connect to the positive end of the external power supply, and the second end of the first resistor is connected to the source of the first MOS tube; the first end of the second resistor is connected to the first end of the first resistor, the second end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor is connected to the source of the first MOS tube; the first end of the second resistor is also connected to the input end of the peak current sampling and holding module, the output end of the peak current sampling and holding module is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first input end of the first comparator, the second end of the fourth resistor is also connected to the source of the first MOS tube through the fifth resistor, the second input end of the first comparator is connected to the second end of the second resistor, and the output end of the first comparator is connected to the input end of the driving circuit.

[0034] In the above technical solution, the second resistor and the third resistor form a voltage-dividing resistor, and the fourth resistor and the fifth resistor form a voltage-dividing resistor. For example, when it is detected that the input current rises to higher than 90% of the peak value of the input current, the driving circuit outputs a low-level signal to the first MOS tube to turn off the first MOS tube; when it is detected that the input current drops to lower than 90% of the peak value of the input current, the driving circuit outputs a high-level signal to the first MOS tube to turn on the first MOS tube, thereby realizing the control of the discharge time of the first capacitor.

[0035] In some optional implementations, the adaptive current detection circuit includes a first resistor, an edge detection module and a signal holding module;

[0036] The first end of the first resistor is used to connect to the positive end of the external power supply, and the second end of the first resistor is connected to the source of the first MOS tube; the input end of the edge detection module is connected to the first end of the first resistor, the output end of the edge detection module is connected to the input end of the signal holding module, and the output end of the signal holding module is connected to the input end of the drive circuit; the edge detection module is used to detect the rising edge and falling edge of the input current, and when the rising edge of the input current is detected, the first signal is output and passes through the signal holding module to control the drive circuit to output a low-level signal to the first MOS tube, so that the first MOS tube is turned off; when the falling edge of the input current is detected, the second signal is output and passes through the signal holding module to control the drive circuit to output a high-level signal to the first MOS tube, so that the first MOS tube is turned on.

[0037] In the above technical solution, the discharge time of the first capacitor can also be controlled by detecting the edge of the input current.

[0038] An embodiment of the present application provides a control device for an LED module, comprising an LED constant current control circuit as described in any one of the above items, and a shell surrounding the control circuit.

[0039] An LED device provided in an embodiment of the present application includes an LED constant current control circuit as described in any one of the above items, and an LED module; the control circuit is connected to the LED module.

[0040] An integrated circuit for an LED module provided in an embodiment of the present application includes: an LED constant current control circuit as described in any of the above items, a lead frame, and a plastic packaging material; the control circuit is arranged on the lead frame, and the plastic packaging material is used to seal the control circuit. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0042] Figure 1 A schematic diagram of an LED constant current control circuit provided in an embodiment of the present application;

[0043] Figure 2 A structural diagram of an LED constant current control circuit provided in the first embodiment of the present application;

[0044] Figure 3 A structural diagram of an LED constant current control circuit provided in the second embodiment of the present application;

[0045] Figure 4A structural diagram of an LED constant current control circuit provided in the third embodiment of the present application;

[0046] Figure 5 A structural diagram of an LED constant current control circuit provided in the fourth embodiment of the present application;

[0047] Figure 6 A structural diagram of an LED constant current control circuit provided in the fifth embodiment of the present application;

[0048] Figure 7 A structural diagram of an LED constant current control circuit provided in the sixth embodiment of the present application;

[0049] Figure 8 A structural diagram of an LED constant current control circuit provided in the seventh embodiment of the present application;

[0050] Fig. 9 A structural diagram of an LED constant current control circuit provided in the eighth embodiment of the present application;

[0051] Fig.10 A structural diagram of an LED constant current control circuit provided in the ninth embodiment of the present application;

[0052] Fig.11 A structural diagram of an LED constant current control circuit provided in the tenth embodiment of the present application;

[0053] Fig.12 This is a structural diagram of an LED constant current control circuit provided in the eleventh embodiment of the present application. DETAILED DESCRIPTION

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

[0055] Please refer to Figure 1 , Figure 1 This is a schematic diagram of an LED constant current control circuit provided in an embodiment of the present application. The LED constant current control circuit includes: a discharge control module, a constant current control module, a first capacitor C1 and a unidirectional conduction module.

[0056] The unidirectional conduction module is used to allow the input current to pass through the unidirectional conduction module to reach the positive end of the first capacitor C1, so as to charge the first capacitor C1. The discharge control module is connected to the first capacitor C1, and the discharge control module is used to allow the first capacitor C1 to discharge when the input voltage is lower than the set value. The first capacitor C1 current discharged by the first capacitor C1 passes through the discharge control module and the constant current control module to reach the load LED, so as to supply power to the load LED; when the input voltage is higher than the set value, the first capacitor C1 is prevented from discharging. The constant current control module is connected to the load LED, and the constant current control module is used to convert the input current or the current of the first capacitor C1 into a constant current, so as to supply power to the load LED with a constant current.

[0057] In the embodiment of the present application, the input current of the external power supply is input into the first capacitor C1 through the unidirectional conduction module to charge the first capacitor C1. The input current or the first capacitor C1 current discharged by the first capacitor C1 is input to the load LED through the constant current control module to realize flicker-free constant current power supply of the load LED. By using the discharge control module, when the input voltage is lower than the set value, the first capacitor C1 is allowed to discharge and power the load LED. When the input voltage is higher than the set value, the first capacitor C1 is prevented from discharging. In this process, by setting a lower set value, the phase angle width of the input current within an input voltage half wave is increased, thereby improving the PF value.

[0058] Among them, the unidirectional conduction module is a device with a PN junction structure, usually a diode. The discharge control module can be a constant current source circuit, and the constant current control module can be a constant current source current or a switch type DCDC. The discharge control module and the constant current control module can be connected to a floating ground or a grounded ground. The constant current control module can be connected to the positive end of the load LED, or to the negative end of the load LED. The discharge control module can be connected to the positive end of the first capacitor C1, or to the negative end of the first capacitor C1. The above situations are described in detail in the following multiple embodiments:

[0059] Please refer to Figure 2 , Figure 2 This is a structural diagram of the LED constant current control circuit provided in the first embodiment of the present application. In this embodiment, the constant current control module is connected to the positive end of the load LED, the discharge control module is connected to the positive end of the first capacitor C1, and the ground end of the constant current control module is connected to the positive end of the load LED, that is, the constant current control module is floating. The unidirectional conduction module uses a first diode D1, the positive end of the first diode D1 is connected to the positive output end of the rectifier module DB, and the negative end of the first diode D1 is connected to the positive end of the first capacitor C1.

[0060] The discharge control module in this embodiment includes: a discharge control logic circuit, a first MOS tube M1 and a first resistor R1. The output end of the discharge control logic circuit is connected to the gate of the first MOS tube M1. The discharge control logic circuit is used to judge whether the input voltage is higher than the set value according to the voltage of the first resistor R1. When the input voltage is higher than the set value, a low-level signal is output to the first MOS tube M1 to turn off the first MOS tube M1; when the input voltage is lower than the set value, a high-level signal is output to the first MOS tube M1 to turn on the first MOS tube M1. In addition, due to the existence of the unidirectional conduction module (the unidirectional conduction module in this embodiment is actually the first diode D1 connected between the positive output end of the rectifier module DB and the positive end of the first capacitor C1), the first MOS tube M1 can adopt a low-voltage MOS tube. Specifically, the first MOS tube M1 and the discharge control logic circuit are integrated with a discharge control chip, and the ground end of the discharge control chip is connected to the input end of the constant current control module, that is, the discharge control chip is floating.

[0061] In the embodiment of the present application, the on-off of the discharge circuit of the first capacitor C1 is realized by turning on and off the first MOS tube M1. The first resistor R1 is used to obtain a sampling voltage that is positively correlated with the input voltage. The discharge control logic circuit outputs a low-level signal or a high-level signal according to the size of the sampling voltage, thereby controlling the on-off of the first MOS tube M1. When the first MOS tube M1 is turned on, the first capacitor C1 is discharged at a constant current, and the input current drops to 0.

[0062] The first end of the discharge control logic circuit is connected to the first end of the first resistor R1, the second end of the first resistor R1 is connected to the source of the first MOS tube M1, the drain of the first MOS tube M1 is connected to the positive end of the first capacitor C1, and the second end of the discharge control logic circuit is connected to the drain of the first MOS tube M1.

[0063] In this embodiment, the discharge control module and the constant current control module are both constant current source circuits. The discharge control module uses the first MOS tube M1 as a switch device, and the constant current control module uses the second MOS tube M2 as a switch device. The first capacitor C1, the first MOS tube M1, the second MOS tube M2 and the load LED constitute a discharge circuit of the first capacitor C1, and because the first diode D1 is connected in parallel at both ends of the first MOS tube M1, the surge current flows to the first capacitor C1 through the first diode D1. The first MOS tube M1 can use a low-voltage MOS tube, and only the second MOS tube M2 needs to be set as a high-voltage MOS tube to meet the voltage withstand requirements of the entire circuit under surge voltage.

[0064] Please refer to Figure 3 , Figure 3 This is a structural diagram of an LED constant current control circuit provided in the second embodiment of the present application. Different from the first embodiment, the discharge control logic circuit in this embodiment is implemented by a first comparator.

[0065] The positive input terminal of the first comparator is used to input a first reference voltage, the negative input terminal of the first comparator is connected to the source of the first MOS tube M1, the output terminal of the first comparator is connected to the gate of the first MOS tube M1, the first end of the first resistor R1 is connected to the source of the first MOS tube M1, and the second end of the first resistor R1 is connected to the positive end of the load LED.

[0066] In the embodiment of the present application, the discharge control logic circuit adopts a first comparator to output a low-level signal or a high-level signal according to the size of the sampling voltage. In the present embodiment, a first reference voltage is input into the positive input terminal of the first comparator, and a voltage of the first resistor R1 is input into the negative input terminal of the first comparator. The voltage of the first resistor R1 is positively correlated with the input voltage. When the first reference voltage is greater than the voltage of the first resistor R1, that is, when the input voltage is lower than the set value, the first comparator outputs a high-level signal to the first MOS tube M1, so that the first MOS tube M1 is turned on, and the first capacitor C1 can be discharged to the load LED through the first MOS tube M1; when the first reference voltage is less than the voltage of the first resistor R1, that is, when the input voltage is higher than the set value, the first comparator outputs a low-level signal to the first MOS tube M1, so that the first MOS tube M1 is turned off, and the discharge circuit of the first capacitor C1 is disconnected.

[0067] Please refer to Figure 4 , Figure 4 This is a structural diagram of an LED constant current control circuit provided in the third embodiment of the present application. Different from the first embodiment, the constant current control module of this embodiment is connected to the output end of the load LED, the discharge control module is connected to the negative end of the first capacitor C1, the unidirectional conduction module uses a first diode D1, the positive end of the first diode D1 is connected to the negative end of the first capacitor C1, the negative end of the first diode D1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the negative output end of the rectifier module DB.

[0068] The discharge control module in this embodiment includes: a discharge control logic circuit, a first MOS tube M1 and a first resistor R1. The output end of the discharge control logic circuit is connected to the gate of the first MOS tube M1, the first end of the discharge control logic circuit is connected to the first end of the first resistor R1, the second end of the first resistor R1 is connected to the drain of the first MOS tube M1, the source of the first MOS tube M1 is connected to the negative end of the first capacitor C1, and the second end of the first resistor R1 is also connected to the negative end of the load LED. Specifically, the discharge control logic circuit and the first MOS tube M1 are integrated with a discharge control chip, and the ground end of the discharge control chip is connected to the output end of the constant current control module, that is, the discharge control chip is floating.

[0069] The discharge control logic circuit is used to determine whether the input voltage is higher than the set value according to the voltage of the first resistor R1. When the input voltage is higher than the set value, a low-level signal is output to the first MOS tube M1 to turn off the first MOS tube M1; when the input voltage is lower than the set value, a high-level signal is output to the first MOS tube M1 to turn on the first MOS tube M1. In addition, due to the existence of the unidirectional conduction module (the unidirectional conduction module in this embodiment is actually the wire between the positive end of the load LED and the positive end of the first capacitor C1), the first MOS tube M1 can use a low-voltage MOS tube.

[0070] In the embodiment of the present application, the on-off of the discharge circuit of the first capacitor C1 is realized by turning on and off the first MOS tube M1. The first resistor R1 is used to obtain a sampling voltage that is positively correlated with the input voltage. The discharge control logic circuit outputs a low-level signal or a high-level signal according to the size of the sampling voltage, thereby controlling the on-off of the first MOS tube M1. When the first MOS tube M1 is turned on, the first capacitor C1 is discharged at a constant current, and the input current drops to 0.

[0071] Please refer to Figure 5 , Figure 5 This is a structural diagram of an LED constant current control circuit provided in the fourth embodiment of the present application. Different from the third embodiment, the discharge control logic circuit of this embodiment adopts a first comparator; the positive input terminal of the first comparator is used to input a first reference voltage, the negative input terminal of the first comparator is connected to the source of the first MOS tube M1, the output terminal of the first comparator is connected to the gate of the first MOS tube M1, the first end of the first resistor R1 is connected to the source of the first MOS tube M1, and the second end of the first resistor R1 is used to connect to the negative end of an external power supply.

[0072] In the embodiment of the present application, the discharge control logic circuit adopts a first comparator to output a low-level signal or a high-level signal according to the size of the sampling voltage. In the present embodiment, a first reference voltage is input into the positive input terminal of the first comparator, and a voltage of the first resistor R1 is input into the negative input terminal of the first comparator. The voltage of the first resistor R1 is positively correlated with the input voltage. When the first reference voltage is greater than the voltage of the first resistor R1, that is, when the input voltage is lower than the set value, the first comparator outputs a high-level signal to the first MOS tube M1, so that the first MOS tube M1 is turned on, and the first capacitor C1 can be discharged to the load LED through the first MOS tube M1; when the first reference voltage is less than the voltage of the first resistor R1, that is, when the input voltage is higher than the set value, the first comparator outputs a low-level signal to the first MOS tube M1, so that the first MOS tube M1 is turned off, and the discharge circuit of the first capacitor C1 is disconnected.

[0073] Please refer to Figure 6 , Figure 6 This is a structural diagram of a LED constant current control circuit provided in the fifth embodiment of the present application. Different from the first embodiment, the ground terminal of the constant current control module in this embodiment is connected to the negative output terminal of the rectifier module DB, that is, the ground terminal of the constant current control module.

[0074] In the embodiment of the present application, the constant current control module adopts a constant current source circuit composed of a second comparator, a second MOS tube M2 and a sampling resistor Rcs. The positive end of the second comparator is used to input a second reference voltage, the negative end of the second comparator is connected to the source of the second MOS tube M2, the source of the second MOS tube M2 is connected to the sampling resistor Rcs, and the output end of the second comparator is connected to the gate of the second MOS tube M2.

[0075] In this embodiment, a constant current source including a first MOS tube M1 and a first resistor R1 is used in the discharge control module, and a first capacitor C1, a first MOS tube M1, a second MOS tube M2 and a load LED form a capacitor discharge loop. The resistance value of the first resistor R1 is greater than the resistance value of the sampling resistor Rcs, so that when the voltages of the two constant current sources fluctuate within the compliance range, the current harmonic components can be controlled within a smaller range.

[0076] Please refer to Figure 7 , Figure 7 This is a structural diagram of the LED constant current control circuit provided for the sixth embodiment of the present application. Different from the fifth embodiment, the discharge control logic circuit in this embodiment is implemented by a first comparator. The positive input terminal of the first comparator is used to input a first reference voltage, the negative input terminal of the first comparator is connected to the source of the first MOS tube M1, the output terminal of the first comparator is connected to the gate of the first MOS tube M1, the first end of the first resistor R1 is connected to the source of the first MOS tube M1, and the second end of the first resistor R1 is connected to the positive end of the load LED.

[0077] Please refer to Figure 8 , Figure 8 This is a structural diagram of the LED constant current control circuit provided for the seventh embodiment of the present application. Different from the first embodiment, the constant current control module of this embodiment adopts a DCDC module, and the positive end of the load LED is also connected to the negative end of the external power supply through the second capacitor C2. The input end of the DCDC module is connected to the negative end of the load LED, the output end of the DCDC module is connected to the first end of the resistor, the second end of the resistor is connected to the negative output end of the rectifier module DB, and the ground end of the DCDC module is connected to the negative output end of the rectifier module DB.

[0078] In the embodiment of the present application, the constant current control module adopts a switch constant current DCDC module. A second capacitor C2 is set between the positive end of the load LED and the negative end of the external power supply. The second capacitor C2 is connected in parallel with the first capacitor C1 to increase the capacitance and extend the service life of the entire circuit.

[0079] Please refer to Fig. 9 , Fig. 9 This is a structural diagram of the LED constant current control circuit provided in the eighth embodiment of the present application. The unidirectional conduction module of this embodiment includes a body diode of the first MOS tube M1, the input end of the body diode is connected to the source of the first MOS tube M1, and the output end of the body diode is connected to the drain of the first MOS tube M1. In the embodiment of the present application, the unidirectional conduction module directly uses the body diode of the first MOS tube M1, which reduces the diode devices and reduces the cost.

[0080] Please refer to Fig.10 , Fig.10The structure diagram of the LED constant current control circuit provided for the ninth embodiment of the present application. The difference from the eighth embodiment is that the one-way conduction module of the present embodiment also includes a first diode D1 and a second diode D2. The rectifier module DB is used to connect an external power supply; the input end of the first diode D1 is connected to the positive input end of the rectifier module DB, the input end of the second diode D2 is connected to the negative input end of the rectifier module DB, and the output ends of the first diode D1 and the second diode D2 are both connected to the first capacitor C1. In the embodiment of the present application, considering that the circuit often generates a very high operating overvoltage when it is struck by lightning and when the inductive load LED or large load LED is turned on and off, this instantaneous overvoltage (or overcurrent) is called a surge voltage (or surge current), which is a transient interference. Therefore, in the present embodiment, the first diode D1 and the second diode D2 are set to deal with the surge voltage.

[0081] Please refer to Fig.11 and Fig.12 , Fig.11 and Fig.12 The LED constant current control circuit structure diagrams are respectively provided in the tenth embodiment and the eleventh embodiment of the present application. Different from the first embodiment, the discharge control module of the tenth embodiment and the eleventh embodiment includes: an adaptive current detection circuit, a first MOS tube M1 and a drive circuit. Among them, the output end of the adaptive current detection circuit is connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the gate of the first MOS tube M1. The adaptive current detection circuit is used to detect the input current and control the drive circuit to output a high level signal to the first MOS tube M1 when the input current starts to decrease, so that the first MOS tube M1 is turned on; when the input current starts to rise, the drive circuit is controlled to output a low level signal to the first MOS tube M1, so that the first MOS tube M1 is turned off.

[0082] For details, please refer to Fig.11 , Fig.11The LED constant current control circuit structure diagram provided for the tenth embodiment of the present application. Among them, the adaptive current detection circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first comparator and a peak current sampling and holding module; the first end of the first resistor R1 is used to connect to the positive end of the external power supply, and the second end of the first resistor R1 is connected to the source of the first MOS tube M1; the first end of the second resistor R2 is connected to the first end of the first resistor R1, the second end of the second resistor R2 is connected to the first end of the third resistor R3, and the second end of the third resistor R3 is connected to the source of the first MOS tube M1; the first end of the second resistor R2 is also connected to the input end of the peak current sampling and holding module, the output end of the peak current sampling and holding module is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first input end of the first comparator, the second end of the fourth resistor is also connected to the source of the first MOS tube through the fifth resistor, the second input end of the first comparator is connected to the second end of the second resistor R2, and the output end of the first comparator is connected to the input end of the driving circuit.

[0083] In the embodiment of the present application, the second resistor R2 and the third resistor R3 form a voltage-dividing resistor, the fourth resistor and the fifth resistor form a voltage-dividing resistor, the second resistor R2 is 25k, the third resistor R3 is 475k, the fourth resistor R4 is 50k, and the fifth resistor R5 is 450k. 90% of the sampling current peak value is input to the positive input end of the first comparator, and 95% of the current sampling current value is input to the negative input end of the first comparator. The sampling current is positively correlated with the input current, so that when the input current rises to a certain value, the first MOS tube is controlled to be disconnected to prevent the first capacitor C1 from discharging; when the input current decreases below a certain value, the first MOS tube is controlled to be turned on to allow the first capacitor C1 to discharge.

[0084] In addition, the constant current control module of this embodiment includes a peak voltage sampling and holding module, a reference voltage module, a second comparator, a second MOS tube M2 and a sampling resistor Rcs, wherein the peak voltage sampling and holding module, the reference voltage module, the second comparator and the second MOS tube M2 are integrated with a constant current control chip, and the ground end of the constant current control chip is connected to the positive end of the load LED. The second end of the first resistor R1 is connected to the drain of the second MOS tube M2, the drain of the second MOS tube M2 is connected to the input end of the peak voltage sampling and holding module, the output end of the peak voltage sampling and holding module is connected to the input end of the reference voltage module, the output end of the reference voltage module is connected to the positive input end of the second comparator, the negative input end of the second comparator is connected to the source of the second MOS tube M2, the output end of the second comparator is connected to the gate of the second MOS tube M2, the source of the second MOS tube M2 is connected to the first end of the sampling resistor Rcs, and the second end of the sampling resistor Rcs is connected to the positive end of the load LED.

[0085] Please refer to Fig.12 , Fig.12 This is a structural diagram of an LED constant current control circuit provided by the eleventh embodiment of the present application. Different from the tenth embodiment, the adaptive current detection circuit of this embodiment includes a first resistor R1, an edge detection module and a signal holding module.

[0086] Among them, the first end of the first resistor R1 is used to connect to the positive end of the external power supply, and the second end of the first resistor R1 is connected to the source of the first MOS tube M1; the input end of the edge detection module is connected to the first end of the first resistor R1, the output end of the edge detection module is connected to the input end of the signal holding module, and the output end of the signal holding module is connected to the input end of the drive circuit; the edge detection module is used to detect the rising edge and falling edge of the input current, and when the rising edge of the input current is detected, the first signal is output and passes through the signal holding module to control the drive circuit to output a low-level signal to the first MOS tube M1, so that the first MOS tube M1 is turned off; when the falling edge of the input current is detected, the second signal is output and passes through the signal holding module to control the drive circuit to output a high-level signal to the first MOS tube M1, so that the first MOS tube M1 is turned on.

[0087] In the embodiment of the present application, the discharge time of the first capacitor C1 can also be controlled by detecting the edge of the input current.

[0088] An embodiment of the present application provides a control device for an LED module, comprising an LED constant current control circuit as described in any one of the above items, and a shell surrounding the control circuit.

[0089] An LED device provided in an embodiment of the present application includes an LED constant current control circuit as described in any one of the above items, and an LED module; the control circuit is connected to the LED module.

[0090] An integrated circuit for an LED module provided in an embodiment of the present application includes: an LED constant current control circuit as described in any of the above items, a lead frame, and a plastic packaging material; the control circuit is arranged on the lead frame, and the plastic packaging material is used to seal the control circuit.

[0091] 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.

[0092] 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.

[0093] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0094] 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.

[0095] The above description is only an embodiment of the present application and is not intended to limit the scope of protection 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 scope of protection of the present application.

Claims

1. An LED constant current control circuit, characterized in that: include: A discharge control module, a constant current control module, a first capacitor and a unidirectional conduction module; The one-way conducting module is used to allow the input current to pass through the one-way conducting module to reach the positive end of the first capacitor, so as to charge the first capacitor; The discharge control module is connected to the first capacitor, and the discharge control module is used to allow the first capacitor to discharge when the input voltage is lower than the set value, and the first capacitor current discharged by the first capacitor passes through the discharge control module and the constant current control module to reach the load to supply power to the load; and when the input voltage is higher than the set value, the discharge of the first capacitor is prevented; The constant current control module is connected to the load, and is used to convert the input current or the first capacitor current into a constant current to provide constant current power supply to the load.

2. The circuit according to claim 1, characterized in that The discharge control module comprises: a discharge control logic circuit, a first MOS tube and a first resistor; The output end of the discharge control logic circuit is connected to the gate of the first MOS tube. The discharge control logic circuit is used to judge whether the input voltage is higher than a set value according to the voltage of the first resistor. When the input voltage is higher than the set value, the discharge control logic circuit outputs a low-level signal to the first MOS tube to turn off the first MOS tube; when the input voltage is lower than the set value, the discharge control logic circuit outputs a high-level signal to the first MOS tube to turn on the first MOS tube.

3. The circuit according to claim 2, characterized in that The first end of the discharge control logic circuit is connected to the first end of the first resistor, the second end of the first resistor is connected to the source of the first MOS transistor, and the drain of the first MOS transistor is connected to the positive end of the first capacitor.

4. The circuit according to claim 2, characterized in that The discharge control logic circuit includes a first comparator; the positive input end of the first comparator is used to input a first reference voltage, the negative input end of the first comparator is connected to the source of the first MOS tube, the output end of the first comparator is connected to the gate of the first MOS tube, the first end of the first resistor is connected to the source of the first MOS tube, and the second end of the first resistor is connected to the positive end of the load.

5. The circuit according to claim 2, characterized in that The first end of the discharge control logic circuit is connected to the first end of the first resistor, the second end of the first resistor is connected to the drain of the first MOS tube, the source of the first MOS tube is connected to the negative end of the first capacitor, and the second end of the first resistor is also connected to the negative end of the load.

6. The circuit according to claim 2, characterized in that The discharge control logic circuit includes a first comparator; the positive input end of the first comparator is used to input a first reference voltage, the negative input end of the first comparator is connected to the source of the first MOS tube, the output end of the first comparator is connected to the gate of the first MOS tube, the first end of the first resistor is connected to the source of the first MOS tube, and the second end of the first resistor is used to be connected to the negative end of an external power supply.

7. The circuit according to claim 1, characterized in that The constant current control module comprises: a second comparator, a second MOS tube and a sampling resistor; The positive terminal of the second comparator is used to input a second reference voltage, the negative terminal of the second comparator is connected to the source of the second MOS tube, the source of the second MOS tube is connected to the sampling resistor, and the output terminal of the second comparator is connected to the gate of the second MOS tube.

8. The circuit according to claim 1, characterized in that The constant current control module includes a DCDC module; The positive terminal of the load is also connected to the negative terminal of the external power supply through a second capacitor.

9. The circuit according to claim 2, characterized in that The one-way conduction module includes a body diode of the first MOS tube, an input end of the body diode is connected to the source of the first MOS tube, and an output end of the body diode is connected to the drain of the first MOS tube.

10. The circuit according to claim 9, characterized in that Also includes: Rectifier module; the rectifier module is used to connect to an external power supply; the unidirectional conduction module also includes a first diode and a second diode; the input end of the first diode is connected to the positive input end of the rectifier module, the input end of the second diode is connected to the negative input end of the rectifier module, and the output ends of the first diode and the second diode are both connected to the first capacitor.

11. The circuit according to claim 1, characterized in that The discharge control module comprises: an adaptive current detection circuit, a first MOS tube and a driving circuit; The output end of the adaptive current detection circuit is connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the gate of the first MOS tube. The adaptive current detection circuit is used to detect the input current and control the drive circuit to output a high-level signal to the first MOS tube when the input current starts to decrease, so that the first MOS tube is turned on; when the input current starts to rise, the drive circuit is controlled to output a low-level signal to the first MOS tube, so that the first MOS tube is turned off.

12. The circuit according to claim 11, characterized in that The adaptive current detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first comparator and a peak current sampling and holding module; The first end of the first resistor is used to connect to the positive end of the external power supply, and the second end of the first resistor is connected to the source of the first MOS tube; the first end of the second resistor is connected to the first end of the first resistor, the second end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor is connected to the source of the first MOS tube; the first end of the second resistor is also connected to the input end of the peak current sampling and holding module, the output end of the peak current sampling and holding module is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first input end of the first comparator, the second end of the fourth resistor is also connected to the source of the first MOS tube through the fifth resistor, the second input end of the first comparator is connected to the second end of the second resistor, and the output end of the first comparator is connected to the input end of the driving circuit.

13. The circuit according to claim 11, characterized in that The adaptive current detection circuit comprises a first resistor, an edge detection module and a signal holding module; The first end of the first resistor is used to connect to the positive end of the external power supply, and the second end of the first resistor is connected to the source of the first MOS tube; The input end of the edge detection module is connected to the first end of the first resistor, the output end of the edge detection module is connected to the input end of the signal holding module, and the output end of the signal holding module is connected to the input end of the drive circuit; the edge detection module is used to detect the rising edge and falling edge of the input current, and when the rising edge of the input current is detected, the first signal is output and the signal holding module is used to control the drive circuit to output a low-level signal to the first MOS tube, so that the first MOS tube is turned off; when the falling edge of the input current is detected, the second signal is output and the signal holding module is used to control the drive circuit to output a high-level signal to the first MOS tube, so that the first MOS tube is turned on.

14. A control device for an LED module, characterized in that: It comprises an LED constant current control circuit as described in any one of claims 1 to 13, and a shell surrounding the control circuit.

15. An LED device, characterized in that: It comprises an LED constant current control circuit as described in any one of claims 1 to 13, and an LED module; the control circuit is connected to the LED module.

16. An integrated circuit for an LED module, characterized in that: include: An LED constant current control circuit, a lead frame, and a plastic packaging material as described in any one of claims 1 to 13; The control circuit is arranged on the lead frame, and the plastic packaging material is used to seal the control circuit.

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