A constant current driving circuit, a constant current driving device and a lamp

Abstract

The present application is applicable to the field of electronic technology, and provides a constant current driving circuit, a constant current driving device and a lamp. First, the voltage at the input end is collected by a peak voltage sampling and holding module to generate an input voltage sampling signal, and the holding voltage at the current moment is averaged according to the peak voltage of the input voltage sampling signal and the holding voltage at the previous moment, and the holding voltage at the current moment is output to a voltage-controlled current source module as an output voltage signal. Then, the voltage-controlled current source module generates a corresponding current signal according to the output voltage signal and a preset second threshold voltage. The constant current threshold control module mirrors the current signal to generate a mirror current signal, and adjusts the constant current threshold according to the mirror current signal to keep the working current flowing out of the load constant, thereby adaptively controlling the constant current threshold when the input voltage fluctuates, and effectively reducing the current ripple caused by the input voltage fluctuation.

Description

Technical Field

[0001] The present application belongs to the field of electronic technology, and in particular relates to a constant current driving circuit, a constant current driving device and a lamp. Background Art

[0002] In a constant current system powered by AC power, the input voltage of the constant current drive circuit is the rectified and filtered AC voltage minus the conduction voltage of the LED light string. When the AC voltage fluctuates, the input voltage of the constant current drive circuit will be lower than the constant current threshold of the constant current drive circuit, causing ripples in the current flowing through the LED light string, causing the entire LED system to flicker and have excessive stroboscopic index. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a constant current drive circuit, a constant current drive device and a lamp, which can adaptively control the constant current threshold when the input voltage fluctuates, effectively reduce the current ripple caused by the input voltage fluctuation, and solve the problems of flickering, excessive stroboscopic index, etc. caused by the input voltage of the constant current drive circuit being lower than the constant current threshold of the constant current drive circuit.

[0004] The present invention provides a constant current driving circuit, which comprises:

[0005] A peak voltage sampling and holding module, used to collect the voltage at the input end to generate an input voltage sampling signal, and obtain the holding voltage at the current moment according to the peak voltage of the input voltage sampling signal and the average value of the holding voltage at the previous moment, and use the holding voltage at the current moment as the voltage value of the output voltage signal;

[0006] a voltage-controlled current source module, connected to the peak voltage sampling and holding module, configured to receive the output voltage signal, and generate a corresponding current signal according to the output voltage signal and a preset second threshold voltage;

[0007] The constant current threshold control module is connected to the voltage-controlled current source module, and is used to mirror the current signal according to a proportional coefficient to generate a mirror current signal, and adjust the constant current threshold according to the mirror current signal to keep the working current flowing through the load constant.

[0008] In one embodiment, the peak voltage sampling and holding module includes:

[0009] An input voltage sampling unit, used for sampling the voltage signal at the input end to generate the input voltage sampling signal;

[0010] a single excitation signal generating unit, connected to the input voltage sampling unit, and configured to generate a first serial single excitation signal and a second serial single excitation signal when the voltage value of the input voltage sampling signal is greater than a first threshold voltage, wherein the second serial single excitation signal is generated after the first serial single excitation signal;

[0011] The sampling voltage averaging unit is connected to the input voltage sampling unit and the single excitation signal generating unit, and is used to collect the peak voltage of the input voltage sampling signal. During the duration of the first serial single excitation signal, the holding voltage at the previous moment is averaged with the peak voltage, and updated to the holding voltage at the current moment as the voltage value of the output voltage signal.

[0012] In one embodiment, the input voltage sampling unit includes: a first resistor and a second resistor;

[0013] The first end of the first resistor is connected to the input end, the second end of the first resistor and the first end of the second resistor are commonly connected to the peak voltage sampling unit, and the second resistor is grounded.

[0014] In one embodiment, the single excitation signal generating unit comprises: a single excitation signal generator and a first operational amplifier;

[0015] The non-inverting input terminal of the first operational amplifier is connected to the voltage sampling unit, the inverting input terminal of the first operational amplifier is connected to the first threshold voltage source, the output terminal of the first operational amplifier is connected to the single excitation signal amplifier, and the first output terminal and the second output terminal of the single excitation signal are both connected to the sampling voltage averaging unit.

[0016] In one embodiment, the sampling voltage averaging unit is also used to collect the average voltage of the input voltage sampling signal, update the average voltage of the current input voltage sampling signal to the hold voltage at the current moment, or update the peak voltage of the current input voltage sampling signal to the hold voltage at the current moment.

[0017] In one embodiment, the sampling voltage averaging unit includes: a second operational amplifier, a first switch tube, a first capacitor, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a second capacitor and a resetter;

[0018] The non-inverting input terminal of the second operational amplifier and the first terminal of the first switch tube are commonly connected to the input voltage sampling unit, the inverting input terminal of the second operational amplifier, the second terminal of the first switch tube, the first terminal of the first capacitor, the first terminal of the second switch tube, and the first terminal of the third switch tube are commonly connected, the second terminal of the first capacitor is grounded, and the output terminal of the second operational amplifier, the control terminal of the first switch tube, and the first terminal of the fourth switch tube are commonly connected;

[0019] The control end of the second switch tube is connected to the first output end of the single excitation signal generating unit, the second end of the third switch tube is grounded, the control end of the third switch tube and the control end of the fourth switch tube are commonly connected to the second output end of the single excitation signal generating unit, the second end of the third switch tube is grounded, the second end of the fourth switch tube is grounded, the second end of the second switch tube, the first end of the fifth switch tube, and the first end of the second capacitor are commonly connected to the voltage-controlled current source module, the second end of the second capacitor is grounded, the second end of the fifth switch tube is grounded, and the control end of the fifth switch tube is connected to the resetter.

[0020] In one embodiment, the voltage-controlled current source module includes: a third operational amplifier, a fourth operational amplifier, a sixth switch tube and a third resistor;

[0021] The first end of the sixth switch tube is connected to the constant current threshold control module, the non-inverting input end of the third operational amplifier is connected to the second threshold voltage source, the inverting input end of the third operational amplifier, the second end of the sixth switch tube and the first end of the third resistor are connected, the control end of the sixth switch tube is connected to the output end of the third operational amplifier, the non-inverting input end of the fourth operational amplifier is connected to the peak voltage sampling and holding module, and the inverting input end of the fourth operational amplifier and the output end of the fourth operational amplifier are commonly connected to the second end of the third resistor.

[0022] In one embodiment, the constant current threshold control module includes:

[0023] A current mirror unit, connected to the voltage-controlled current source module, and configured to perform mirror amplification on the current signal to generate a mirror current signal;

[0024] The working current regulating unit is connected to the current mirror unit and adjusts the constant current threshold according to the mirror current signal so that the working current flowing out of the load maintains a constant current.

[0025] An embodiment of the present application also provides a constant current driving device, comprising a constant current driving circuit as described in any of the above embodiments.

[0026] An embodiment of the present application further provides a lamp, comprising: a light source load; and a constant current driving circuit as described in any one of the above embodiments, wherein the constant current driving circuit is connected to the light source load.

[0027] The embodiments of the present application provide a constant current drive circuit, a constant current drive device and a lamp. The constant current drive circuit includes: a peak voltage sampling and holding module, a voltage-controlled current source module and a constant current threshold control module. First, the peak voltage sampling and holding module collects the voltage at the input end to generate an input voltage sampling signal, and the peak voltage of the input voltage sampling signal and the holding voltage at the previous moment are averaged to obtain the holding voltage at the current moment, and the holding voltage at the current moment is output to the voltage-controlled current source module as an output voltage signal. The initial value of the holding voltage is 0, and then the voltage-controlled current source module generates a corresponding current signal according to the output voltage signal and a preset second threshold voltage. The constant current threshold control module mirrors the current signal to generate a mirror current signal, and adjusts the constant current threshold according to the mirror current signal to keep the working current flowing out of the load constant current, thereby adaptively controlling the constant current threshold when the input voltage fluctuates, effectively reducing the current ripple caused by the input voltage fluctuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 It is a structural diagram of a traditional LED constant current system;

[0030] Figure 2 A schematic diagram of the structure of a constant current drive circuit provided in an embodiment of the present application;

[0031] Figure 3 A circuit schematic diagram of a constant current drive circuit provided in an embodiment of the present application;

[0032] Figure 4 An application schematic diagram of a constant current drive circuit provided in an embodiment of the present application;

[0033] Figure 5 A schematic diagram of voltage changes provided in an embodiment of the present application;

[0034] Figure 6 This is an application schematic diagram of another constant current drive circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0036] The term "comprising" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method or system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. In addition, the terms "first", "second" and "third" etc. are used to distinguish different objects, rather than to describe a specific order.

[0037] In order to solve the above technical problems, the present application embodiment provides a constant current driving circuit. Figure 2 As shown, the constant current driving circuit is connected to the load, and the constant current driving circuit includes: a peak voltage sampling and holding module 10, a voltage-controlled current source module 20 and a constant current threshold control module 30.

[0038] Specifically, the peak voltage sampling and holding module 10 is used to collect the voltage at the input end to generate an input voltage sampling signal, and to average the peak voltage of the input voltage sampling signal and the holding voltage at the previous moment to obtain the holding voltage at the current moment, and output the holding voltage at the current moment as the output voltage signal to the voltage-controlled current source module. In specific applications, the initial value of the holding voltage can be a preset reference voltage, and the preset reference voltage can be 0, that is, at the startup moment, the holding voltage is 0, and when calculating the average voltage value, the holding voltage at the previous moment is 0V.

[0039] The voltage-controlled current source module 20 is connected to the peak voltage sampling and holding module 10, and the voltage-controlled current source module 20 is used to generate a corresponding current signal according to the output voltage signal and a preset second threshold voltage; the constant current threshold control module 30 is connected to the voltage-controlled current source module 20 and the load, and is used to mirror the current signal, generate a mirror current signal, and adjust the constant current threshold according to the mirror current signal, so that the working current flowing out of the load remains constant, thereby adaptively controlling the constant current threshold when the input voltage fluctuates, and effectively reducing the current ripple caused by the input voltage fluctuation.

[0040] In this embodiment, in order to achieve adaptive adjustment of the constant current threshold of the constant current driving circuit, the peak voltage sampling and holding module 10 first averages the peak voltage of the input voltage sampling signal and the holding voltage at the previous moment to obtain the holding voltage at the current moment, and outputs the holding voltage at the current moment as the output voltage signal to the voltage-controlled current source module, and then the voltage-controlled current source module 20 generates a corresponding current signal according to the output voltage signal and a preset second threshold voltage, the constant current threshold control module 30 mirrors the current signal to generate a mirror current signal, and adjusts the constant current threshold according to the mirror current signal to keep the working current flowing out of the load constant current, thereby adaptively controlling the constant current threshold when the input voltage fluctuates, and effectively reducing the current ripple caused by the input voltage fluctuation.

[0041] In a specific application embodiment, the input end of the peak voltage sampling and holding module 10 receives an external input voltage signal, and the output end thereof is connected to the voltage-controlled current source module 20, and is used to sample the peak voltage of the current external input voltage signal in real time, and cache the voltage at the previous moment, and thereby obtain the average value of the peak voltage and the voltage at the previous moment, and update the average value to the voltage value at the current moment, and output it to the voltage-controlled current source module 20 as an output voltage signal.

[0042] One end of the voltage-controlled current source module 20 is connected to the peak voltage sampling and holding module 10 , and the other end is connected to the constant current threshold control module 30 , and can convert the output voltage signal provided by the peak voltage sampling and holding module 10 to obtain a corresponding current signal.

[0043] The constant current threshold control module 30 performs mirror amplification on the current signal according to a certain proportionality coefficient K, and adjusts the constant current threshold according to the mirror current signal obtained by the mirror amplification, so as to keep the working current flowing out of the load constant.

[0044] In one embodiment, see Figure 3 As shown, the peak voltage sampling and holding module 10 includes: an input voltage sampling unit 11, a single-excitation signal generating unit 12, and a sampling voltage averaging unit 13, wherein the input voltage sampling unit 11 is used to sample the voltage signal at the input end to generate an input voltage sampling signal; the single-excitation signal generating unit 12 is connected to the input voltage sampling unit 11, and is used to generate a first serial single-excitation signal and a second serial single-excitation signal when the voltage value of the input voltage sampling signal is greater than a first threshold voltage, wherein the second serial single-excitation signal is generated after the first serial single-excitation signal.

[0045] The sampling voltage averaging unit 13 is connected to the input voltage sampling unit 11 and the single excitation signal generating unit 12. The sampling voltage averaging unit 13 is used to receive the input voltage sampling signal and collect the peak voltage of the input voltage sampling signal; store the voltage value of the input voltage sampling signal at the previous moment according to the first serial single excitation signal and the second serial single excitation signal, and determine the voltage average value of the input voltage sampling signal and the input voltage sampling signal at the previous moment to generate an output voltage signal.

[0046] In this embodiment, two serial single excitation signals are generated by a single excitation signal generating unit 12 after power-on delay, and the sampling voltage averaging unit 13 performs charge and discharge adjustment on the collected voltage signal according to the two serial single excitation signals to determine the voltage peak value of the input voltage sampling signal. During the duration of the first serial single excitation signal, the holding voltage at the previous moment is averaged with the peak voltage, and the averaged voltage is updated to the holding voltage at the current moment as the voltage value of the output voltage signal.

[0047] In one embodiment, see Figure 3 As shown, the input voltage sampling unit 11 includes: a first resistor R1 and a second resistor R2; the first end of the first resistor R1 is connected to the input end, the second end of the first resistor R1 and the first end of the second resistor R2 are commonly connected to the sampling voltage averaging unit 13, and the second resistor R2 is grounded.

[0048] In this embodiment, the first resistor R1 and the second resistor R2 form a voltage divider circuit to perform voltage division processing on the voltage at the input end to generate an input voltage sampling signal.

[0049] In one embodiment, see Figure 3 As shown, the single excitation signal generating unit 12 includes: a single excitation signal generator 121 and a first operational amplifier Y1; the non-inverting input terminal of the first operational amplifier Y1 is connected to the voltage sampling unit, the inverting input terminal of the first operational amplifier Y1 is connected to the first threshold voltage source, the output terminal of the first operational amplifier Y1 is connected to the single excitation signal amplifier, and the first output terminal and the second output terminal of the single excitation signal generator are both connected to the sampling voltage averaging unit 13.

[0050] In a single AC half-wave cycle, when the voltage of V1 is greater than the voltage Vref1 of the inverting input terminal of the first operational amplifier Y1, the single-excitation signal generator 121 will delay generating two serial single-excitation signals, namely, the first serial single-excitation signal CKA and the second serial single-excitation signal CKB, wherein the second serial single-excitation signal CKB is generated some time after the first serial single-excitation signal CKA ends.

[0051] In one embodiment, the sampling voltage averaging unit 13 includes: a second operational amplifier Y2 , a first switch tube M1 , a first capacitor C1 , a second switch tube M2 , a third switch tube M3 , a fourth switch tube M4 , a fifth switch tube M5 , a second capacitor C2 and a resetter 141 .

[0052] The non-inverting input terminal of the second operational amplifier Y2 and the first terminal of the first switch tube M1 are connected to the input voltage sampling unit 11; the inverting input terminal of the second operational amplifier Y2, the second terminal of the first switch tube M1, and the first terminal of the first capacitor C1 are connected to the first terminal of the second switch tube M2; the second terminal of the first capacitor C1 is grounded; the output terminal of the second operational amplifier Y2 and the control terminal of the first switch tube M1 are connected to the first terminal of the fourth switch tube.

[0053] The control end of the second switch tube M2 is connected to the single excitation signal generating unit 12, the first end of the second switch tube M2 and the first end of the third switch tube M3 are connected in common, the second end of the third switch tube M3 is grounded, the control end of the third switch tube M3 and the control end of the fourth switch tube M4 are connected in common to the single excitation signal generating unit 12, the second end of the third switch tube M3 is grounded, the second end of the fourth switch tube M4 is grounded, the second end of the second switch tube M2, the first end of the fifth switch tube M5, and the first end of the second capacitor C2 are connected in common to the voltage-controlled current source module 20, the second end of the second capacitor C2 is grounded, the second end of the fifth switch tube M5 is grounded, and the control end of the fifth switch tube M5 is connected to the reset device 141.

[0054] In this embodiment, the second operational amplifier Y2, the first switch tube M1, and the first capacitor C1 form a peak voltage sampling circuit. The voltage value of the input voltage sampling signal can be set to V1. The voltage value of the common terminal of the first switch tube M1 and the first capacitor C1 is V2. When V2<V1, the first switch tube M1 is turned on, and V2 is continuously charged until the voltage V2≥V1 on the first capacitor C1, the first switch tube M1 is turned off, and the V2 charging circuit is closed. At this time, the V2 voltage is the peak voltage of V1.

[0055] In one embodiment, the first switch tube M1 , the second switch tube M2 , the third switch tube M3 , the fourth switch tube M4 , and the fifth switch tube M5 are N-type MOS tubes.

[0056] The first serial single excitation signal CKA is output to the control end of the second switch tube M2, and the second serial single excitation signal CKB is output to the control ends of the third switch tube M3 and the fourth switch tube M4. The first serial single excitation signal CKA turns on the second switch tube M2. At this time, the voltage V2 is averaged with the voltage V4 at the first end of the second capacitor C2. The second serial single excitation signal CKB turns on the third switch tube M3 and the fourth switch tube M4, so that the voltage V2 is reduced to zero, and the first switch tube M1 is turned off.

[0057] In a specific application, the average voltage value after averaging processing is updated to the voltage value at the current moment as the voltage value of the output voltage signal, and the voltage value at the current moment is transmitted to the voltage-controlled current source module 20 at the same time. For example, the average value is accumulated and calculated in the form of (((1+0) / 2+2) / 2)+3) / 2…, and the output voltage signal is output to the voltage-controlled current source module 20. When the input voltage fluctuates, the constant current threshold is adaptively controlled, thereby effectively reducing the current ripple caused by the input voltage fluctuation.

[0058] In one embodiment, the sampling voltage averaging unit 13 is further used to collect the average voltage of the input voltage sampling signal, and update the average voltage of the current input voltage sampling signal to the holding voltage at the current moment.

[0059] In this embodiment, the sampling voltage averaging unit 13 performs charge and discharge regulation on the collected voltage signal according to two serial single excitation signals to determine the average voltage of the input voltage sampling signal. For example, the conduction and shutdown of the second switch tube M2 are controlled by the first serial single excitation signal CKA, and the conduction and shutdown of the third switch tube M3 and the fourth switch tube M4 are controlled by the second serial single excitation signal CKB, so as to realize the voltage collection of the input voltage sampling signal and control the average processing process of the voltage V2 and the voltage V4.

[0060] Specifically, the second operational amplifier Y2, the first switch tube M1, and the first capacitor C1 form a voltage sampling circuit. The voltage value of the input voltage sampling signal can be set to V1. The voltage value of the common terminal of the first switch tube M1 and the first capacitor C1 is V2. When V2<V1, the first switch tube M1 is turned on, and V2 is continuously charged until the voltage V2≥V1 on the first capacitor C1, the first switch tube M1 is turned off, and the V2 charging circuit is closed. At this time, the V2 voltage is the average voltage of V1.

[0061] In one embodiment, the sampling voltage averaging unit 13 is further used to update the peak voltage of the current input voltage sampling signal to the holding voltage at the current moment.

[0062] In this embodiment, the sampling voltage averaging unit 13 performs charge and discharge regulation on the collected voltage signal according to two serial single excitation signals, controls the on and off of the second switch tube M2 through the first serial single excitation signal CKA, and controls the on and off of the third switch tube M3 and the fourth switch tube M4 through the second serial single excitation signal CKB, and directly updates the peak voltage of the input voltage sampling signal to the holding voltage at the current moment.

[0063] In one embodiment, the voltage-controlled current source module 20 includes: a third operational amplifier Y3, a fourth operational amplifier Y4, a sixth switch tube M6 and a third resistor R3; the first end of the sixth switch tube M6 is connected to the constant current threshold control module 30, the non-inverting input end of the third operational amplifier Y3 is connected to the second threshold voltage source, the inverting input end of the third operational amplifier Y3, the second end of the sixth switch tube M6 and the first end of the third resistor R3 are connected, the control end of the sixth switch tube M6 is connected to the output end of the third operational amplifier Y3, the non-inverting input end of the fourth operational amplifier Y4 is connected to the peak voltage sampling and holding module 10, and the inverting input end of the fourth operational amplifier Y4 and the output end of the fourth operational amplifier Y4 are commonly connected to the second end of the third resistor R3.

[0064] In this embodiment, the third operational amplifier Y3, the fourth operational amplifier Y4, the sixth switch tube M6 and the third resistor R3 form a voltage-controlled current source, thereby providing a current signal for the constant current threshold control module 30, wherein the non-inverting input terminal of the third operational amplifier Y3 is connected to the second threshold voltage source, and the voltage value of the non-inverting input terminal thereof is Vref2, and the non-inverting input terminal of the fourth operational amplifier Y4 is connected to the peak voltage sampling and holding module 10, and its voltage value is V4. Since the resistance value of the third resistor R3 is much larger than the on-resistance of the sixth switch tube M6, the current flowing through the sixth switch tube M6 is I1=(Vref2-V4) / R3; wherein Vref2 is the voltage value of the second threshold voltage provided by the second threshold voltage source, and V4 is the voltage value of the output voltage signal generated by the peak voltage sampling and holding module 10.

[0065] In one embodiment, see Figure 3 As shown, the constant current threshold control module 30 includes: a current mirror unit 31 and a working current adjustment unit 32; the current mirror unit 31 is connected to the voltage-controlled current source module 20, and is used to mirror the current signal to generate a mirror current signal; the working current adjustment unit 32 is connected to the current mirror unit 31 and the load, and adjusts the constant current threshold according to the mirror current signal to keep the working current flowing out of the load constant.

[0066] In this embodiment, see Figure 3 As shown, the seventh switch tube M7 and the eighth switch tube M8 form a current mirror circuit, and the current flowing through the eighth switch tube M8 is I2=K*I1, wherein the size of the proportionality coefficient K is determined by the size ratio of the seventh switch tube M7 and the eighth switch tube M8.

[0067] In one embodiment, see Figure 3 As shown, the working current regulating unit 32 includes: a fifth operational amplifier Y5, a ninth switch tube M9, a fourth resistor R4 and a fifth resistor R5.

[0068] Specifically, the non-inverting input terminal of the fifth operational amplifier Y5 is connected to the second threshold voltage source, the inverting input terminal of the fifth operational amplifier Y5 and the first end of the fourth resistor R4 are commonly connected to the current mirror unit 31, the output terminal of the fifth operational amplifier Y5 is connected to the control terminal of the ninth switch tube M9, the first end DRAIN of the ninth switch tube M9 is connected to the load, the second end of the ninth switch tube M9, the second end of the fourth resistor R4 and the first end of the fifth resistor R5 are commonly connected, and the second end of the fifth resistor R5 is grounded.

[0069] In one embodiment, the ninth switch tube M9 is an N-type MOS tube.

[0070] In this embodiment, the fourth resistor R4 is connected in series with the eighth switch tube M8, and the current flowing through the fourth resistor R4 is also I2. Therefore, the voltage at the common point of the second end of the ninth switch tube M9, the second end of the fourth resistor R4, and the first end of the fifth resistor R5 is V5=Vref2-I2*R4. Therefore, the current flowing through the load and the ninth switch tube M9 is:

[0071]

[0072] Figure 4 For the application schematic diagram of the constant current drive circuit applied to the LED constant current system, see Figure 4 As shown, the load is an LED light string, the first end of the ninth switch tube M9 is connected to the current output end of the LED light string, the input end of the peak voltage sampling and holding module 10 is connected to the output end of the rectifier bridge DB, and the direct current output by the rectifier bridge DB is processed by the first diode D1 and the third capacitor C3, and then output to the LED light string.

[0073] Figure 5 The schematic diagram of the voltage changes of V1, V2, V4, and V5 in several cycles is shown. Figure 4 and Figure 5 As shown, in the initial state of power-on, the voltage of V4 is zero. After several cycles, V4 reaches the voltage of V2, that is, reaches the peak voltage of V1. When the mains voltage decreases, the peak value of V1 decreases, resulting in a decrease in the voltage of V4, so that the current flowing through the LED and the ninth switch tube M9 decreases. Since the current flowing through the ninth switch tube M9 decreases, the constant current threshold of the ninth switch tube M9 will also decrease accordingly, so the current flowing through the load can still maintain a constant current.

[0074] See also Figure 6 As shown, by adding a thyristor dimmer 40 between the rectifier bridge and the AC power supply AC, the constant current threshold is controlled according to the input voltage after the thyristor dimmer 40 is phase-cut, so as to ensure that the current ripple of the LED lamp string is very small when the thyristor is phase-cut to a small angle, thereby optimizing the LED flickering caused by the thyristor's own phase-cutting wave.

[0075] An embodiment of the present application also provides a constant current driving device, comprising a constant current driving circuit as described in any of the above embodiments.

[0076] An embodiment of the present application further provides a lamp, comprising: a light source load; and a constant current driving circuit as described in any one of the above embodiments, wherein the constant current driving circuit is connected to the light source load.

[0077] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0078] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0079] 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.

[0080] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0081] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A constant current drive circuit, It is characterized in that The constant current driving circuit is connected to a load, and the constant current driving circuit comprises: A peak voltage sampling and holding module, used to collect the voltage at the input end to generate an input voltage sampling signal, and obtain the holding voltage at the current moment according to the peak voltage of the input voltage sampling signal and the average value of the holding voltage at the previous moment, and use the holding voltage at the current moment as the voltage value of the output voltage signal; a voltage-controlled current source module, connected to the peak voltage sampling and holding module, configured to receive the output voltage signal, and generate a corresponding current signal according to the output voltage signal and a preset second threshold voltage; a constant current threshold control module, connected to the voltage-controlled current source module, for mirroring the current signal according to a proportional coefficient to generate a mirror current signal, and adjusting the constant current threshold according to the mirror current signal to keep the working current flowing through the load constant; The peak voltage sampling and holding module comprises: An input voltage sampling unit, used to sample the voltage signal at the input end to generate the input voltage sampling signal; a single excitation signal generating unit, connected to the input voltage sampling unit, and configured to generate a first serial single excitation signal and a second serial single excitation signal when the voltage value of the input voltage sampling signal is greater than a first threshold voltage, wherein the second serial single excitation signal is generated after the first serial single excitation signal; A sampling voltage averaging unit is connected to the input voltage sampling unit and the single excitation signal generating unit, and is used to collect the peak voltage of the input voltage sampling signal, and during the duration of the first serial single excitation signal, average the holding voltage at the previous moment and the peak voltage, and update the averaged voltage to the holding voltage at the current moment as the voltage value of the output voltage signal; The sampling voltage averaging unit includes: a second operational amplifier, a first switch tube, a first capacitor, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a second capacitor and a resetter; The non-inverting input terminal of the second operational amplifier and the first terminal of the first switch tube are commonly connected to the input voltage sampling unit, the inverting input terminal of the second operational amplifier, the second terminal of the first switch tube, the first terminal of the first capacitor, the first terminal of the second switch tube, and the first terminal of the third switch tube are commonly connected, the second terminal of the first capacitor is grounded, and the output terminal of the second operational amplifier, the control terminal of the first switch tube, and the first terminal of the fourth switch tube are commonly connected; The control end of the second switch tube is connected to the first output end of the single excitation signal generating unit, the second end of the third switch tube is grounded, the control end of the third switch tube and the control end of the fourth switch tube are commonly connected to the second output end of the single excitation signal generating unit, the second end of the third switch tube is grounded, the second end of the fourth switch tube is grounded, the second end of the second switch tube, the first end of the fifth switch tube, and the first end of the second capacitor are commonly connected to the voltage-controlled current source module, the second end of the second capacitor is grounded, the second end of the fifth switch tube is grounded, and the control end of the fifth switch tube is connected to the resetter.

2. The constant current driving circuit according to claim 1, It is characterized in that The input voltage sampling unit comprises: a first resistor and a second resistor; The first end of the first resistor is connected to the input end, the second end of the first resistor and the first end of the second resistor are commonly connected to the peak voltage sampling unit, and the second resistor is grounded.

3. The constant current driving circuit according to claim 1, It is characterized in that The single excitation signal generating unit comprises: a single excitation signal generator and a first operational amplifier; The non-inverting input terminal of the first operational amplifier is connected to the voltage sampling unit, the inverting input terminal of the first operational amplifier is connected to the first threshold voltage source, the output terminal of the first operational amplifier is connected to the single-excitation signal amplifier, and the first output terminal and the second output terminal of the single-excitation signal are connected to the sampling voltage averaging unit.

4. The constant current driving circuit according to claim 1, It is characterized in that The sampling voltage averaging unit is also used to collect the average voltage of the input voltage sampling signal, update the average voltage of the current input voltage sampling signal to the current holding voltage, or update the peak voltage of the current input voltage sampling signal to the current holding voltage.

5. The constant current driving circuit according to claim 1, It is characterized in that The voltage-controlled current source module includes: a third operational amplifier, a fourth operational amplifier, a sixth switch tube and a third resistor; The first end of the sixth switch tube is connected to the constant current threshold control module, the non-inverting input end of the third operational amplifier is connected to the second threshold voltage source, the inverting input end of the third operational amplifier, the second end of the sixth switch tube and the first end of the third resistor are connected, the control end of the sixth switch tube is connected to the output end of the third operational amplifier, the non-inverting input end of the fourth operational amplifier is connected to the peak voltage sampling and holding module, and the inverting input end of the fourth operational amplifier and the output end of the fourth operational amplifier are commonly connected to the second end of the third resistor.

6. The constant current driving circuit according to claim 1, It is characterized in that The constant current threshold control module comprises: A current mirror unit, connected to the voltage-controlled current source module, and configured to perform mirror amplification on the current signal to generate a mirror current signal; The working current regulating unit is connected to the current mirror unit and adjusts the constant current threshold according to the mirror current signal so that the working current flowing through the load remains constant.

7. A constant current driving device, It is characterized in that Comprising a constant current drive circuit as described in any one of claims 1-6.

8. A lamp, It is characterized in that include: Light source load; And the constant current driving circuit as described in any one of claims 1 to 6, wherein the constant current driving circuit is connected to the light source load.

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