CN218959159U - Dimmable constant current circuit - Google Patents
Dimmable constant current circuit Download PDFInfo
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- CN218959159U CN218959159U CN202223075949.7U CN202223075949U CN218959159U CN 218959159 U CN218959159 U CN 218959159U CN 202223075949 U CN202223075949 U CN 202223075949U CN 218959159 U CN218959159 U CN 218959159U
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Abstract
The application provides a dimming constant current circuit, wherein a channel voltage and a reference voltage of an output end of an LED module are respectively input into two input ends of an error amplifier, and the error amplifier outputs amplified error voltage; multiplying the amplified error voltage with an input voltage sampling signal through a multiplier to obtain a peak current given signal; comparing the peak current given signal with the peak current of the MOS tube of the booster circuit to obtain a comparison result; and controlling the on-off of the MOS tube according to the comparison result, correcting the power factor and stabilizing the channel voltage to be the reference voltage, wherein the output voltage is equal to the sum of the voltages at the two ends of the LED module and the channel voltage, so that the output voltage is represented as the voltage at the two ends of the LED module under the condition that the channel voltage is unchanged, and the voltages at the two ends of the constant current source are not increased when the channel voltage is stabilized to be the reference voltage, thereby avoiding serious heating of the chip and influencing the carrying capacity.
Description
Technical Field
The application relates to the technical field of electronics, in particular to a dimmable constant current circuit.
Background
The LED light source is a light source based on a light emitting diode and has the advantages of low-voltage power supply, low energy consumption, strong applicability, high stability, short response time, no pollution to the environment, multicolor light emission and the like. With the continuous development of LED technology, LED light sources are widely used, and scenes such as markets, factories, houses, etc. use a large number of LED light sources as illumination or decoration, and adjust the brightness of the LED light sources when necessary. Along with the application of LED illumination global markets, special illumination such as stage lamps, projection backlight, intelligent home illumination and the like has higher and higher requirements on dimming precision and dimming depth.
The existing LED dimming circuit cannot realize the function of following output voltage, so that the efficiency is low during dimming, and the chip heats seriously. In addition, the existing LED dimming circuit is required to realize full-range dimming, the output voltage is required to be larger than the voltage of the minimum current of the LED, so that the output voltage is required to be set very high when dimming is not performed, the voltage withstand requirement of an output capacitor is high, the cost is increased, meanwhile, the requirement of safety compliance is met by further insulation distance, and in addition, the higher the output voltage is, the lower the system efficiency is.
Disclosure of Invention
An aim of the embodiment of the application is to provide a dimming constant current circuit for solve the problem that the existing LED dimming circuit can not realize the function of output voltage following, so that the dimming efficiency is low and the chip is serious in heating.
The embodiment of the application provides a but constant current circuit adjusts luminance, includes: the LED power supply comprises an input sampling circuit, a booster circuit, an LED module and a control module;
the input end of the booster circuit is used for being connected with an external power supply, and the input end of the booster circuit is also connected with an input sampling circuit; the output end of the booster circuit is connected with the input end of the LED module, and the output end of the LED module is connected to the editable current constant current source;
the control module comprises an editable current constant current source, an error amplifier, a multiplier, an operational amplifier, a logic circuit and a driving module;
the output end of the LED module is connected with the second input end of the error amplifier, the first input end of the error amplifier is used for inputting the reference voltage, the output end of the error amplifier is connected with the first input end of the multiplier, the second input end of the multiplier is connected with the sampling voltage output end of the input sampling circuit, the output end of the multiplier is connected with the second input end of the operational amplifier, the first input end of the operational amplifier is connected with the source electrode of the MOS tube of the boost circuit, and the output end of the operational amplifier is connected to the grid electrode of the MOS tube of the boost circuit after sequentially passing through the logic circuit and the driving circuit.
In the technical scheme, the channel voltage and the reference voltage at the output end of the LED module are respectively input into two input ends of the error amplifier, and the error amplifier compares the channel voltage with the reference voltage and amplifies the channel voltage to obtain amplified error voltage; the input sampling circuit samples the voltage of the input end and obtains an input voltage sampling signal, and the amplified error voltage is multiplied with the input voltage sampling signal through the multiplier to obtain a peak current given signal; comparing the peak current given signal with the peak current of the MOS tube of the booster circuit through an operational amplifier to obtain a comparison result; the logic circuit and the driving module control the on-off of the MOS tube according to the comparison result, power factor correction is carried out, the channel voltage is stabilized to be the reference voltage, and the output voltage is equal to the sum of the voltages at the two ends of the LED module and the channel voltage, so that the output voltage is represented as to follow the voltages at the two ends of the LED module under the condition that the channel voltage is unchanged, the voltages at the two ends of the constant current source are not increased when the channel voltage is stabilized to be the reference voltage, and serious heating of a chip and influence on the carrying capacity are avoided. Therefore, when the voltage at two ends of the LED module is reduced by dimming through the PWM signal, the dimmable constant current circuit of the embodiment reduces the output voltage in a following way, so that the system efficiency during dimming is improved, and the problem of serious chip heating is avoided.
In some alternative embodiments, the control module further comprises a voltage selection circuit; the editable current constant current source comprises at least one constant current source;
the LED module comprises a plurality of LED lamp strings connected in parallel, each LED lamp string is grounded after passing through a constant current source and a grounding resistor, the output end of each LED lamp string is connected to a voltage selection circuit, the voltage selection circuit is used for selecting the voltage with the lowest voltage value from the voltages of the output ends of the LED lamp strings to output, and the output end of the voltage selection circuit is connected to the second input end of the error amplifier.
In some optional embodiments, the device further comprises an output sampling circuit, and an output end of the boost circuit is connected with the output sampling circuit;
the control module also comprises a voltage comparison circuit;
the sampling voltage output end of the input sampling circuit is connected with the first input end of the voltage comparison circuit, the sampling voltage output end of the output sampling circuit is connected with the second input end of the voltage comparison circuit, and the output end of the voltage comparison circuit is connected with the second input end of the logic circuit.
In the above technical solution, when the external PWM signal is used to dim the LED module, the voltage at both ends of the LED module may be smaller than the peak value of the input voltage along with the decrease of the current, at this time, since the output voltage is smaller than or equal to the input voltage, the boost circuit is not needed to boost, so that the input sampling voltage of the input sampling circuit is compared with the output sampling voltage of the output sampling circuit, and when the output voltage is determined to be smaller than or equal to the input voltage, the logic circuit and the driving circuit control the MOS transistor to be disconnected.
In some alternative embodiments, the input sampling circuit comprises a second resistor and a third resistor which are connected in series, and one end of the second resistor connected with the third resistor is a sampling voltage output end of the input sampling circuit;
the output sampling circuit comprises a fourth resistor and a fifth resistor which are connected in series, and one end of the fourth resistor and the fifth resistor which are connected is a sampling voltage output end of the output sampling circuit.
In some optional embodiments, the boost circuit includes an inductor, a MOS tube and a diode, the input end of the inductor is connected to an external power supply, the output end of the inductor is connected to the drain electrode of the MOS tube, the source electrode of the MOS tube is grounded after passing through a grounding resistor, the output end of the inductor is further connected to the input end of the diode, and the output end of the diode is connected to the input end of the LED module.
In the technical scheme, when the MOS tube is conducted, an external power supply charges the inductor; when the MOS tube is disconnected, the inductor discharges. The output voltage is equal to the sum of the input voltage and the voltages at two ends of the inductor, and the output voltage is larger than the input voltage, so that the boosting is realized.
In some alternative embodiments, the output of the inductor is connected to the logic circuit through a first resistor.
In the technical scheme, the inductor is connected to the logic circuit through the first resistor, so that the logic circuit can acquire the inductor current, and zero-crossing detection of the inductor current is realized.
In some optional embodiments, the device further comprises a rectifying module, wherein an input end of the rectifying module is connected with an external power supply, and an output end of the rectifying module is connected with an input sampling circuit.
In the above technical scheme, the external power supply is usually an AC power supply, and the AC voltage is converted into a sinusoidal half-wave dc voltage by the rectifying module.
In some alternative embodiments, the editable current constant current source further comprises a DAC module connected to the controlled end of the constant current source.
In the technical scheme, an external PWM signal is input into the DAC module, and is converted into the direct current voltage which changes along with the PWM dimming duty ratio through the DAC module, the direct current voltage is used as the set voltage of the corresponding constant current source, the voltage changes, and the current of the corresponding constant current source channel changes along with the change, so that the brightness adjustment of the LED lamp is realized.
The embodiment of the application provides a control method of a dimmable constant current circuit, which comprises the following steps: the LED power supply comprises an input sampling circuit, a booster circuit, an LED module and a control module; the input end of the booster circuit is used for being connected with an external power supply, and the input end of the booster circuit is also connected with an input sampling circuit; the output end of the booster circuit is connected with the input end of the LED module, and the output end of the LED module is connected to the editable current constant current source; the sampling voltage output end of the input sampling circuit is connected with the control module;
the control method is applied to the control module, and comprises the following steps: obtaining the channel voltage of the output end of the LED module; comparing the channel voltage with the reference voltage, and amplifying to obtain an amplified error voltage; acquiring an input voltage sampling signal output by an input sampling circuit, and multiplying the amplified error voltage by the input voltage sampling signal to obtain a peak current given signal; comparing the peak current given signal with the peak current of the MOS tube of the booster circuit to obtain a comparison result; and according to a comparison result, controlling the on-off of the MOS tube to realize power factor correction and stabilizing the channel voltage to be a reference voltage, so that the output voltage follows the voltages at two ends of the LED module.
In some optional embodiments, the dimmable constant current circuit further comprises an output sampling circuit, and a sampling voltage output end of the output sampling circuit is connected with the control module; the control method further comprises the following steps: and acquiring an output voltage sampling signal output by the output sampling circuit, comparing the input voltage sampling signal with the output voltage sampling signal, and controlling the MOS tube to be disconnected if the output voltage is smaller than or equal to the input voltage.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a dimmable constant current circuit according to an embodiment of the present disclosure;
fig. 2 is a block diagram of a dimmable constant current circuit according to an embodiment of the present disclosure;
fig. 3 is a flowchart of a control method of a dimmable constant current circuit according to an embodiment of the present application;
fig. 4 is a functional block diagram of a dimmable constant current circuit in one embodiment.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
Referring to fig. 1, fig. 1 is a schematic diagram of a dimmable constant current circuit provided in an embodiment of the present application, where the dimmable constant current circuit includes: the LED power supply comprises an input sampling circuit, a booster circuit, an LED module and a control module; the input end of the booster circuit is used for being connected with an external power supply, and the input end of the booster circuit is also connected with an input sampling circuit; the output end of the booster circuit is connected with the input end of the LED module, and the output end of the LED module is connected to the editable current constant current source; the control module comprises an editable current constant current source, an error amplifier, a multiplier, an operational amplifier, a logic circuit and a driving module; the output end of the LED module is connected with the second input end of the error amplifier, the first input end of the error amplifier is used for inputting the reference voltage, the output end of the error amplifier is connected with the first input end of the multiplier, the second input end of the multiplier is connected with the sampling voltage output end of the input sampling circuit, the output end of the multiplier is connected with the second input end of the operational amplifier, the first input end of the operational amplifier is connected with the source electrode of the MOS tube of the boost circuit, and the output end of the operational amplifier is connected to the grid electrode of the MOS tube of the boost circuit after sequentially passing through the logic circuit and the driving circuit.
In the technical scheme, the channel voltage and the reference voltage at the output end of the LED module are respectively input into two input ends of the error amplifier, and the error amplifier compares the channel voltage with the reference voltage and amplifies the channel voltage to obtain amplified error voltage; the input sampling circuit samples the voltage of the input end and obtains an input voltage sampling signal, and the amplified error voltage is multiplied with the input voltage sampling signal through the multiplier to obtain a peak current given signal; comparing the peak current given signal with the peak current of the MOS tube of the booster circuit through an operational amplifier to obtain a comparison result; the logic circuit and the driving module control the on-off of the MOS tube according to the comparison result, power factor correction is carried out, the channel voltage is stabilized to be the reference voltage, and the output voltage is equal to the sum of the voltages at the two ends of the LED module and the channel voltage, so that the output voltage is represented as to follow the voltages at the two ends of the LED module under the condition that the channel voltage is unchanged, the voltages at the two ends of the constant current source are not increased when the channel voltage is stabilized to be the reference voltage, and serious heating of a chip and influence on the carrying capacity are avoided. Therefore, when the voltage at two ends of the LED module is reduced by dimming through the PWM signal, the dimmable constant current circuit of the embodiment reduces the output voltage in a following way, so that the system efficiency during dimming is improved, and the problem of serious chip heating is avoided.
Referring to fig. 4, fig. 4 is a functional block diagram of a dimmable constant current circuit in an embodiment, and in this embodiment, the dimmable constant current circuit further includes a rectifying module and an overvoltage protection module, where the rectifying module is configured to rectify an external power supply and output the rectified external power supply to an input end of an input sampling circuit, and the overvoltage protection module is configured to monitor an output end of a boost circuit to perform overvoltage protection.
Specifically, referring to fig. 2, fig. 2 is a block diagram of a dimmable constant current circuit according to an embodiment of the present application.
In this embodiment, the control module is a control chip, and the control chip includes a plurality of pin ports, which are respectively: HV terminal, vcc terminal, comp terminal, ground terminal, VS terminal, OVP terminal, CS terminal, ZCD terminal, GATE terminal, and LED 1-to LEDn-terminals (only LED3 is shown in the drawing by way of example), set1-setn terminals (only set3 is shown in the drawing by way of example), PWM 1-PWMn terminals (only PWM3 is shown in the drawing by way of example). The HV end is used for supplying power to the chip at high voltage; the vcc terminal is used for a constant voltage source inside the chip; comp is used for loop compensation; the grounding end is used for grounding the chip; the VS end is used for collecting input voltage; the OVP end is used for collecting output voltage and outputting overvoltage protection when open-circuit protection is realized; the CS end is used for collecting the current of the MOS tube; the ZCD end is used for detecting zero crossing of the inductance current; the GATE end is used for external power MOS driving; the LED 1-to LEDn-ends are the input ends of the constant current source in the chip; set1 to setn ends are pins for setting the current of the constant current source in the chip; PWM1 to PWMN are dimming signal input pins. The following details are set forth:
the VS end of the control chip is connected with the sampling voltage output end of the input sampling circuit, and the VS end receives the input sampling voltage signal. The input sampling circuit comprises a second resistor R2 and a third resistor R3 which are connected in series, and one end of the second resistor R2 and one end of the third resistor R3 which are connected are sampling voltage output ends of the input sampling circuit.
The boost circuit comprises an inductor L1, a MOS tube Q1 and a diode D1, wherein the input end of the inductor L1 is connected with the positive electrode output end of the rectifying module BD, the output end of the inductor L1 is connected with the drain electrode of the MOS tube Q1, the source electrode of the MOS tube Q1 is grounded after passing through a grounding resistor, the output end of the inductor L1 is also connected with the input end of the diode D1, and the output end of the diode D1 is connected with the input end of the LED module. The input end of the rectifying module is connected with an external power supply, the positive output end of the rectifying module is connected with a second resistor R2, a capacitor Cin is connected between the positive output end and the negative output end of the rectifying module, the external power supply is an Alternating Current (AC) power supply, and the alternating current voltage is converted into sine half-wave direct current voltage through the rectifying module. The diode D1 is further grounded through the polar capacitor Co, and the voltage at two ends of the polar capacitor Co is the output voltage boosted by the booster circuit.
When the MOS tube Q1 is conducted, the current output by the positive end of the rectifying module BD returns to the negative end of the rectifying module BD through the inductor L1, the MOS tube Q1 and the resistor R9, and at the moment, the rectified external power supply charges the inductor; when the MOS tube Q1 is disconnected, the current output by the positive end of the rectifying module BD returns to the negative end of the rectifying module BD after passing through the inductor L1, the diode D1, the LED module, the constant current source in the control chip and the grounding resistor, at the moment, the inductor L1 discharges, the output voltage (namely, the voltage at two ends of the capacitor Co) is equal to the sum of the input voltage (namely, the voltage at two ends of the capacitor Cin) and the voltage at two ends of the inductor L1, and the output voltage is larger than the input voltage, so that the boosting is realized.
In this embodiment, the LED module includes three parallel LED strings, it should be clear that the LED module may include n LED strings, where n is an integer greater than or equal to 1, and correspondingly, the control chip has n constant current source setting ends of set1-setn, for example, when n is equal to 3 in this embodiment: the first LED lamp string LED1s is grounded after passing through the constant current source I1 and the grounding resistor R6, the second LED lamp string LED2s is grounded after passing through the constant current source I2 and the grounding resistor R7, and the third LED lamp string LED3s is grounded after passing through the constant current source I3 and the grounding resistor R8.
The negative terminal of the LED1s is also connected to the first input end of the voltage selection circuit, the negative terminal of the LED2s is also connected to the second input end of the voltage selection circuit, the negative terminal of the LED3s is also connected to the third input end of the voltage selection circuit, the voltage selection circuit is used for selecting the voltage with the lowest voltage value from the voltages of the output ends of the 3 LED lamp strings to output, and the output end of the voltage selection circuit is connected to the second input end of the error amplifier.
In the control chip, the multiplier multiplies the output of the error amplifier EA by the input voltage sampling signal collected at the VS end to obtain a peak current given signal, and inputs the peak current given signal to the second input end of the operational amplifier COMP. The first input end of the operational amplifier COMP is connected with the CS end of the control chip, the CS end of the control chip is connected with the source electrode of the MOS tube Q1, and the CS end is used for inputting the peak current of the MOS tube Q1. The operational amplifier compares the peak current given signal with the peak current, and inputs the comparison result into the logic circuit, the logic circuit generates a corresponding control signal, and then the corresponding drive signal is generated through the drive circuit, the output end of the drive circuit is connected with the GATE end of the control chip, the GATE end is connected to the grid electrode of the MOS tube Q1, and the on and off of the MOS tube Q1 are controlled through the GATE end.
In some optional embodiments, the dimmable constant current circuit further comprises an output sampling circuit, and an output end of the boost circuit is connected with the output sampling circuit; the output sampling circuit comprises a fourth resistor R4 and a fifth resistor R5 which are connected in series, the output end of the diode D1 is grounded through the fourth resistor R4 and the fifth resistor R5 in sequence, one end, connected with the fourth resistor R4 and the fifth resistor R5, of the output sampling circuit is a sampling voltage output end of the output sampling circuit, and the sampling voltage output end of the output sampling circuit is connected to an OVP end of the control chip. The control module of this embodiment further includes a voltage comparison circuit, a first input terminal of the voltage comparison circuit is connected to a VS terminal of the control chip, a second input terminal of the voltage comparison circuit is connected to an OVP terminal of the control chip, and an output terminal of the voltage comparison circuit is connected to a second input terminal of the logic circuit.
In the above technical solution, when the external PWM signal is used to dim the LED module, the voltage at both ends of the LED module may be smaller than the peak value of the input voltage along with the decrease of the current, at this time, since the output voltage is smaller than or equal to the input voltage, the boost circuit is not needed to boost, so that the input sampling voltage of the input sampling circuit is compared with the output sampling voltage of the output sampling circuit, and when the output voltage is determined to be smaller than or equal to the input voltage, the logic circuit and the driving circuit control the MOS transistor to be disconnected.
In this embodiment, the output terminal of the inductor is further connected to the third input terminal of the logic circuit through the first resistor R1. The inductor is connected to the logic circuit through the first resistor, so that the logic circuit can acquire the inductor current, and zero-crossing detection of the inductor current is realized.
In some alternative embodiments, the editable current constant current source includes a DAC module and at least one constant current source, the DAC module being connected to the controlled end of the constant current source. In this embodiment, the external PWM1 signal is input to the first input terminal of the DAC module through the PWM1 terminal of the control chip, the external PWM2 signal is input to the second input terminal of the DAC module through the PWM2 terminal of the control chip, the external PWM3 signal is input to the third input terminal of the DAC module through the PWM3 terminal of the control chip, and so on. Converting the direct current voltage which changes along with the PWM dimming duty ratio into a direct current voltage by a DAC module, wherein the direct current voltage is used as a set voltage of a corresponding constant current source, the voltage changes, and the current of a corresponding constant current source channel changes along with the change, so that the brightness adjustment of the LED lamp is realized, for example, in the embodiment, a PWM1 signal is converted into a first set voltage, and the first set voltage corresponds to a constant current source I1, so that the brightness adjustment of an LED1s lamp string is realized; converting the PWM2 signal into a second set voltage, wherein the second set voltage corresponds to the constant current source I2, so that the brightness adjustment of the LED2s light string is realized; the PWM3 signal is converted into a third set voltage, and the third set voltage corresponds to the constant current source I3, so that brightness adjustment of the LED3s light string is realized. In some embodiments, the high-precision fast DAC built in the control chip can convert the high-precision PWM signal into a precisely varying dc voltage, can achieve a dimming depth of 0.1%, a dimming precision of 0.1%, and overall dimming without flicker.
The control chip further comprises a band gap reference module and a voltage stabilizer, one end of the voltage stabilizer is connected to the HV end of the control chip, the other end of the voltage stabilizer is connected to the band gap reference module, and one end, connected with the band gap reference module, of the voltage stabilizer is further connected to the vcc end of the control chip.
In some embodiments, the logic and drive circuits may also be used for overvoltage protection, overcurrent protection, over-temperature protection, and the like.
Referring to fig. 3, fig. 3 is a flowchart illustrating steps of a control method of a dimmable constant current circuit according to an embodiment of the present disclosure. Wherein, adjustable light constant current circuit includes: the LED power supply comprises an input sampling circuit, a booster circuit, an LED module and a control module; the input end of the booster circuit is used for being connected with an external power supply, and the input end of the booster circuit is also connected with an input sampling circuit; the output end of the booster circuit is connected with the input end of the LED module, and the output end of the LED module is connected to the editable current constant current source; the sampling voltage output end of the input sampling circuit is connected with the control module;
the control method is applied to the control module, and comprises the following steps:
s1, obtaining channel voltage of an output end of an LED module;
s2, comparing the channel voltage with a reference voltage, and amplifying to obtain an amplified error voltage;
s3, acquiring an input voltage sampling signal output by an input sampling circuit, and multiplying the amplified error voltage by the input voltage sampling signal to obtain a peak current given signal;
s4, comparing the peak current given signal with the peak current of the MOS tube of the booster circuit to obtain a comparison result;
and S5, controlling the on-off of the MOS tube according to the comparison result to realize power factor correction and stabilizing the channel voltage to be the reference voltage, so that the output voltage follows the voltages at two ends of the LED module.
In some optional embodiments, the dimmable constant current circuit further comprises an output sampling circuit, and a sampling voltage output end of the output sampling circuit is connected with the control module;
the control method further comprises the following steps: and acquiring an output voltage sampling signal output by the output sampling circuit, comparing the input voltage sampling signal with the output voltage sampling signal, and controlling the MOS tube to be disconnected if the output voltage is smaller than or equal to the input voltage.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.
Further, the units described as separate units may or may not be physically separate, and units displayed as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of 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.
Furthermore, functional modules in various embodiments of the present application may be integrated together to form a single portion, or each module may exist alone, or two or more modules may be integrated to form a single portion.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (8)
1. A dimmable constant current circuit, comprising: the LED power supply comprises an input sampling circuit, a booster circuit, an LED module and a control module;
the input end of the booster circuit is used for being connected with an external power supply, and the input end of the booster circuit is also connected with the input sampling circuit; the output end of the booster circuit is connected with the input end of the LED module, and the output end of the LED module is connected to an editable current constant current source;
the control module comprises the editable current constant current source, an error amplifier, a multiplier, an operational amplifier, a logic circuit and a driving module;
the output end of the LED module is connected with the second input end of the error amplifier, the first input end of the error amplifier is used for inputting reference voltage, the output end of the error amplifier is connected with the first input end of the multiplier, the second input end of the multiplier is connected with the sampling voltage output end of the input sampling circuit, the output end of the multiplier is connected with the second input end of the operational amplifier, the first input end of the operational amplifier is connected with the source electrode of the MOS tube of the boost circuit, and the output end of the operational amplifier is connected to the grid electrode of the MOS tube of the boost circuit after sequentially passing through the logic circuit and the driving circuit.
2. The dimmable constant current circuit according to claim 1, wherein said control module further comprises a voltage selection circuit, said editable current constant current source comprising at least one constant current source;
the LED module comprises a plurality of LED lamp strings connected in parallel, each LED lamp string is grounded after passing through a constant current source and a grounding resistor, the output end of each LED lamp string is connected to the voltage selection circuit, the voltage selection circuit is used for selecting the voltage with the lowest voltage value from the voltages of the output ends of the LED lamp strings to output, and the output end of the voltage selection circuit is connected to the second input end of the error amplifier.
3. The dimmable constant current circuit of claim 1, further comprising an output sampling circuit, an output of said boost circuit being connected to said output sampling circuit;
the control module further comprises a voltage comparison circuit;
the sampling voltage output end of the input sampling circuit is connected with the first input end of the voltage comparison circuit, the sampling voltage output end of the output sampling circuit is connected with the second input end of the voltage comparison circuit, and the output end of the voltage comparison circuit is connected with the second input end of the logic circuit.
4. The dimmable constant current circuit of claim 3, wherein said input sampling circuit comprises a second resistor and a third resistor connected in series, one end of said second resistor and said third resistor being connected as a sampling voltage output end of said input sampling circuit;
the output sampling circuit comprises a fourth resistor and a fifth resistor which are connected in series, and one end of the fourth resistor and the fifth resistor which are connected is a sampling voltage output end of the output sampling circuit.
5. The dimmable constant current circuit of claim 1, wherein the boost circuit comprises an inductor, a MOS tube and a diode, wherein an input end of the inductor is connected to an external power supply, an output end of the inductor is connected to a drain electrode of the MOS tube, a source electrode of the MOS tube is grounded after passing through a grounding resistor, an output end of the inductor is further connected to an input end of the diode, and an output end of the diode is connected to an input end of the LED module.
6. The dimmable constant current circuit of claim 5, wherein an output of said inductor is connected to said logic circuit through a first resistor.
7. The dimmable constant current circuit of claim 1, further comprising a rectifying module, wherein an input terminal of the rectifying module is connected to an external power source, and an output terminal of the rectifying module is connected to the input sampling circuit.
8. The dimmable constant current circuit according to claim 2, wherein said editable current constant current source further comprises a DAC module, said DAC module being connected to a controlled terminal of the constant current source.
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