CN114845438A - LED drive circuit - Google Patents

LED drive circuit Download PDF

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Publication number
CN114845438A
CN114845438A CN202210333420.6A CN202210333420A CN114845438A CN 114845438 A CN114845438 A CN 114845438A CN 202210333420 A CN202210333420 A CN 202210333420A CN 114845438 A CN114845438 A CN 114845438A
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China
Prior art keywords
resistor
sampling
triode
circuit
led
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CN202210333420.6A
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Chinese (zh)
Inventor
赵松林
李真龙
顾勇
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Shanghai Kostal Huayang Automotive Electric Co Ltd
Kostal Shanghai Mechatronic Co Ltd
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Shanghai Kostal Huayang Automotive Electric Co Ltd
Kostal Shanghai Mechatronic Co Ltd
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Application filed by Shanghai Kostal Huayang Automotive Electric Co Ltd, Kostal Shanghai Mechatronic Co Ltd filed Critical Shanghai Kostal Huayang Automotive Electric Co Ltd
Priority to CN202210333420.6A priority Critical patent/CN114845438A/en
Publication of CN114845438A publication Critical patent/CN114845438A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

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Abstract

The application relates to the technical field of LED driving, and discloses an LED driving circuit which comprises a sampling amplifying circuit, a sampling resistor and a feedback control circuit; the first end of the sampling resistor is connected with the power supply, the second end of the sampling resistor is connected with the first end of the LED, and the second end of the LED is connected with the feedback control circuit; the sampling amplifying circuit is connected with the sampling resistor in parallel and is used for sampling and amplifying the voltage of the sampling resistor; the sampling amplifying circuit is also connected with the feedback control circuit so as to control the on-off of the feedback control circuit according to the sampling voltage output by the sampling amplifying circuit and further control the on-off of the LED drive circuit. By adopting the technical scheme, the sampling amplifying circuit is utilized to sample and amplify the voltages at two ends of the sampling resistor, then the sampling voltage is input to the feedback control circuit, and when the sampling voltage reaches the voltage for conducting the feedback control circuit, the feedback control circuit cuts off a loop of the LED driving circuit, so that the timely discovery and the stop of the driving when the LED is in overcurrent are realized.

Description

LED drive circuit
Technical Field
The application relates to the technical field of LED driving, in particular to an LED driving circuit.
Background
A Light Emitting Diode (LED) is a commonly used light emitting device, emits light by energy released by recombination of electrons and holes, and is widely used in the field of illumination. Because of the improvement of the brightness and the reduction of the price of the light emitting diode, in addition to the long service life and the electricity saving, the driving and controlling are simpler and easier than neon lamps, the neon lamp can not only twinkle, but also change color, and is widely applied to automotive interior, and the driving circuit is an important component of LED products.
However, in a specific implementation, an overcurrent condition occurs in the LED, and the current flowing through the LED is often small and difficult to detect, and if the overcurrent condition cannot be found in time and the driving of the LED is stopped, the LED may be damaged.
Therefore, how to timely find and stop driving when the LED is in an overcurrent state is a problem to be solved by those skilled in the art.
Disclosure of Invention
The application aims to provide an LED driving circuit which is used for timely finding and stopping driving when an LED is in an overcurrent state.
In order to solve the above technical problem, the present application provides an LED driving circuit, including:
the sampling amplifying circuit, the sampling resistor and the feedback control circuit;
the first end of the sampling resistor is connected with a power supply, the second end of the sampling resistor is connected with the first end of the LED, and the second end of the LED is connected with the feedback control circuit;
the sampling amplifying circuit is connected with the sampling resistor in parallel and is used for sampling and amplifying the voltage of the sampling resistor;
the sampling amplifying circuit is also connected with the feedback control circuit so as to control the on-off of the feedback control circuit according to the sampling voltage output by the sampling amplifying circuit, and further control the on-off of the LED drive circuit.
Preferably, the feedback control circuit includes: the circuit comprises a first triode, a second triode, a first resistor, a second resistor and a third resistor;
the base of first triode is connected the output of sampling amplifier circuit with the first end of first resistance, the projecting pole of first triode with the second end ground connection of first resistance, the collecting electrode of first triode is connected the first end of second resistance with the first end of third resistance and the base of second triode, the second end of second resistance is connected the power, the second end of third resistance with the projecting pole ground connection of second triode, the collecting electrode of second triode is connected the second end of LED.
Preferably, the method further comprises the following steps: MCU;
the input end of the MCU is connected with the output end of the sampling amplifying circuit, the output end of the MCU is connected with the base electrode of the first triode so as to compare the received sampling voltage with the threshold value, and when the sampling voltage exceeds the threshold value, a control signal is output to the base electrode of the first triode so as to cut off the LED driving circuit.
Preferably, the method further comprises the following steps: a fourth resistor and a fifth resistor;
the first end of the fourth resistor is connected with the output end of the MCU, the second end of the fourth resistor is connected with the base of the first triode and the first end of the first resistor, the first end of the fifth resistor is connected with the collector of the first triode and the first end of the second resistor, and the second end of the fifth resistor is connected with the base of the second triode and the first end of the third resistor.
Preferably, the feedback control circuit includes: the third triode, the comparator, a sixth resistor and a seventh resistor;
the non inverting input end of the comparator is connected with the comparison voltage, the inverting input end of the comparator is connected with the output end of the sampling amplifying circuit, the output end of the comparator is connected with the first end of the sixth resistor, the first end of the seventh resistor and the base electrode of the third triode, the emitting electrode of the third triode is grounded with the second end of the sixth resistor, the second end of the seventh resistor is connected with the power supply, and the collecting electrode of the third triode is connected with the second end of the LED.
Preferably, the method further comprises the following steps: an eighth resistor, a ninth resistor, and a tenth resistor;
the first end of the eighth resistor is connected with the inverting input end of the comparator and the output end of the sampling amplifying circuit, the second end of the eighth resistor is grounded, the first end of the ninth resistor and the first end of the tenth resistor are connected with the non-inverting input end of the comparator in common, the second end of the ninth resistor is connected with the power supply, and the second end of the tenth resistor is grounded.
Preferably, the sampling amplification circuit includes: the first operational amplifier, the eleventh resistor, the twelfth resistor, the thirteenth resistor and the fourteenth resistor;
the first end of the eleventh resistor is connected to the first end of the sampling resistor, the second end of the eleventh resistor is connected to the first end of the twelfth resistor and the non-inverting input terminal of the first operational amplifier, the first end of the thirteenth resistor is connected to the second end of the sampling resistor, the second end of the thirteenth resistor is connected to the inverting input terminal of the first operational amplifier and the first end of the fourteenth resistor, and the second end of the fourteenth resistor is connected to the output terminal of the first operational amplifier, and the first end of the eleventh resistor and the first end of the fourteenth resistor are collectively used as the output terminal of the sampling amplifier circuit.
Preferably, the sampling amplifying circuit further includes: the second operational amplifier, a fifteenth resistor, a sixteenth resistor and a seventeenth resistor;
a first end of the fifteenth resistor is connected to a second end of the fourteenth resistor and an output end of the first operational amplifier, a second end of the fifteenth resistor is connected to a non-inverting input end of the second operational amplifier, a first end of the sixteenth resistor and a first end of the seventeenth resistor are connected to an inverting input end of the second operational amplifier, a second end of the sixteenth resistor is grounded, and a second end of the seventeenth resistor and an output end of the second operational amplifier are connected to serve as an output end of the sampling amplifying circuit.
Preferably, the method further comprises the following steps: an eighteenth resistor;
and the first end of the eighteenth resistor is connected with the second end of the sampling resistor and the first end of the thirteenth resistor, and the second end of the eighteenth resistor is connected with the first end of the LED.
Preferably, the method further comprises the following steps: a nineteenth resistor;
and the first end of the nineteenth resistor is connected with the output end of the sampling amplification circuit, and the second end of the nineteenth resistor is connected with the input end of the MCU.
The LED drive circuit comprises a sampling amplifying circuit, a sampling resistor and a feedback control circuit; the first end of the sampling resistor is connected with the power supply, the second end of the sampling resistor is connected with the first end of the LED, and the second end of the LED is connected with the feedback control circuit; the sampling amplifying circuit is connected with the sampling resistor in parallel and is used for sampling and amplifying the voltage of the sampling resistor; the sampling amplifying circuit is also connected with the feedback control circuit so as to control the on-off of the feedback control circuit according to the sampling voltage output by the sampling amplifying circuit and further control the on-off of the LED drive circuit. By adopting the technical scheme, the sampling amplifying circuit is utilized to sample and amplify the voltages at two ends of the sampling resistor, then the sampling voltage is input to the feedback control circuit, and when the sampling voltage reaches the voltage for conducting the feedback control circuit, the feedback control circuit cuts off a loop of the LED driving circuit, so that the timely discovery and the stop of the driving when the LED is in overcurrent are realized.
Drawings
In order to more clearly illustrate the embodiments of the present application, the drawings needed for the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained by those skilled in the art without inventive effort.
Fig. 1 is a circuit diagram of an LED driving circuit according to an embodiment of the present disclosure;
fig. 2 is a circuit diagram of another feedback control circuit provided in an embodiment of the present application;
the reference numbers are as follows: 1 is a sampling amplifying circuit, 2 is a feedback control circuit, and 3 is an MCU.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the present application.
The core of the application is to provide an LED driving circuit which is used for timely finding and stopping driving when an LED is in overcurrent.
In order that those skilled in the art will better understand the disclosure, the following detailed description will be given with reference to the accompanying drawings.
Fig. 1 is a circuit diagram of an LED driving circuit according to an embodiment of the present application, and as shown in fig. 1, the circuit includes:
the device comprises a sampling amplifying circuit 1, a sampling resistor R and a feedback control circuit 2;
the first end of the sampling resistor R is connected with a power supply 12V, the second end of the sampling resistor R is connected with the first end of the LED, and the second end of the LED is connected with the feedback control circuit 2;
the sampling amplifying circuit 1 is connected with the sampling resistor R in parallel and is used for sampling and amplifying the voltage of the sampling resistor R;
the sampling amplifying circuit 1 is also connected with the feedback control circuit 2 so as to control the on-off of the feedback control circuit 2 according to the sampling voltage output by the sampling amplifying circuit 1, and further control the on-off of the LED drive circuit.
The sampling amplifying circuit 1 in this embodiment is configured to obtain voltages at two ends of the sampling resistor R and amplify the voltages, and it can be understood that the larger the current flowing through the sampling resistor R is, the larger the sampling voltage output by the sampling amplifying circuit 1 is, and when the LED driving circuit is overcurrent, the sampling voltage at this time can turn on the feedback control circuit 2, and then turn off the LED driving circuit to stop driving of the LED. Similarly, when the LED driving circuit is not over-current, the sampling voltage can not cut off the LED driving circuit, and the LED can still be normally driven. In a specific implementation, the sampling amplification circuit 1 generally uses an operational amplifier, and the amplification factor is set by a resistor connected thereto. When amplification is carried out, multi-stage amplification can be carried out so as to improve the amplification factor, but the defects are that static working points of all stages can influence each other, and the zero drift phenomenon is easy to occur.
The feedback control circuit 2 can be controlled by using a switch, such as a MOS transistor, a triode, etc., and the feedback control circuit 2 can control the on/off of the LED driving circuit according to the sampling voltage. The triode is a current control device, and the purpose of controlling the output current is achieved by controlling the base current, so that the base always has certain current, and the input resistance of the triode is low. The MOS transistor is a voltage control device, the output current of the MOS transistor depends on the voltage between the gate and the source, and the gate does not substantially draw current, so the input resistance of the MOS transistor is high.
The LED driving circuit provided by the embodiment comprises a sampling amplifying circuit, a sampling resistor and a feedback control circuit; the first end of the sampling resistor is connected with the power supply, the second end of the sampling resistor is connected with the first end of the LED, and the second end of the LED is connected with the feedback control circuit; the sampling amplifying circuit is connected with the sampling resistor in parallel and is used for sampling and amplifying the voltage of the sampling resistor; the sampling amplifying circuit is also connected with the feedback control circuit so as to control the on-off of the feedback control circuit according to the sampling voltage output by the sampling amplifying circuit and further control the on-off of the LED drive circuit. By adopting the technical scheme, the sampling amplifying circuit is utilized to sample and amplify the voltages at two ends of the sampling resistor, then the sampling voltage is input to the feedback control circuit, and when the sampling voltage reaches the voltage for conducting the feedback control circuit, the feedback control circuit cuts off a loop of the LED driving circuit, so that the timely discovery and the stop of the driving when the LED is in overcurrent are realized.
On the basis of the above embodiments, the present embodiment provides a specific feedback control circuit 2, as shown in fig. 1, the feedback control circuit 2 includes: the circuit comprises a first triode Q1, a second triode Q2, a first resistor R1, a second resistor R2 and a third resistor R3;
the base electrode of the first triode Q1 is connected with the output end of the sampling amplifying circuit 1 and the first end of the first resistor R1, the emitter electrode of the first triode Q1 and the second end of the first resistor R1 are grounded, the collector electrode of the first triode Q1 is connected with the first end of the second resistor R2, the first end of the third resistor R3 and the base electrode of the second triode Q2, the second end of the second resistor R2 is connected with the power supply, the second end of the third resistor R3 and the emitter electrode of the second triode Q2 are grounded, and the collector electrode of the second triode Q2 is connected with the second end of the LED.
In this embodiment, the sampling voltage output from the output terminal of the sampling amplifying circuit 1 controls the conducting state of the first transistor Q1, and when the sampling voltage reaches the conducting voltage of the first transistor Q1, the base of the second transistor Q2 is grounded, so as to cut off the LED driving circuit. When the first triode Q1 can not be conducted by the sampling voltage, the power supply +5V enables the second triode Q2 to be conducted, the LED driving circuit works normally, and the LED drives normally. The corresponding amplification factor of the sampling amplification circuit 1 needs to be designed according to the conduction voltage of the first triode Q1, so that the first triode Q1 is conducted when overcurrent occurs, and the LED is normally driven when overcurrent does not occur. In this embodiment, the first transistor Q1 and the second transistor Q2 are both NPN transistors, the first resistor R1 and the third resistor R3 are both bias resistors, and the second resistor R2 is a pull-up resistor.
The present embodiment provides a specific feedback control circuit capable of stopping the driving of the LED when the LED driving circuit is over-current.
In the above embodiment, the method for controlling the on/off of the feedback control circuit 2 through the sampling voltage output by the output terminal of the sampling amplifying circuit 1 is described, the method needs to design the amplification factor of the sampling amplifying circuit 1 according to the conducting voltage of the first triode Q1, and the amplification factor is limited by the conducting voltage, which is not favorable for accurate sampling of the voltage.
Therefore, on the basis of the above embodiment, in this embodiment, the method further includes: an MCU 3;
the input end of the MCU3 is connected with the output end of the sampling amplifying circuit 1, the output end of the MCU3 is connected with the base electrode of the first triode Q1 so as to compare the received sampling voltage with the threshold value, and when the sampling voltage exceeds the threshold value, a control signal is output to the base electrode of the first triode Q1 so as to cut off the LED driving circuit.
The MCU3 in this embodiment is configured to receive a sampling voltage, where the larger the current flowing through the sampling resistor R is, the larger the sampling voltage is, and when the sampling voltage exceeds a threshold value stored in the MCU3, it is considered that the LED driving circuit is in an overcurrent state, and at this time, the MCU3 outputs a high level to the base of the first transistor Q1 to turn on the first transistor Q1, so as to cut off the LED driving circuit.
The LED drive circuit that this embodiment provided judges sampling voltage through increasing MCU3, and MCU3 output high level cuts off LED drive circuit when drive circuit overflows for sampling amplification circuit 1 is no longer limited by the turn-on voltage to the magnification of sampling resistance R both ends voltage, can improve sampling voltage through increasing the magnification, with realize more accurate voltage under the condition of overflowing and judge.
In this embodiment, the high level output by the MCU3 may damage the first transistor Q1, and therefore, the present embodiment further includes: a fourth resistor R4 and a fifth resistor R5;
the first end of the fourth resistor R4 is connected with the output end of the MCU3, the second end of the fourth resistor R4 is connected with the base of the first triode Q1 and the first end of the first resistor R1, the first end of the fifth resistor R5 is connected with the collector of the first triode Q1 and the first end of the second resistor R2, and the second end of the fifth resistor R5 is connected with the base of the second triode Q2 and the first end of the third resistor R3.
In the embodiment, the current is limited by adding the fourth resistor and the fifth resistor, so that the first triode and the second triode are protected.
While a specific feedback control circuit 2 is described in the above embodiment, another specific feedback control circuit 2 is also provided in the present embodiment. Fig. 2 is a circuit diagram of another feedback control circuit according to an embodiment of the present application, and as shown in fig. 2, the feedback control circuit 2 includes: the circuit comprises a third triode Q3, a comparator X3, a sixth resistor R6 and a seventh resistor R7;
the non-inverting input end of the comparator X3 is connected with the comparison voltage, the inverting input end of the comparator X3 is connected with the output end of the sampling amplifying circuit 1, the output end of the comparator X3 is connected with the first end of the sixth resistor R6, the first end of the seventh resistor R7 and the base of the third triode Q3, the emitter of the third triode Q3 and the second end of the sixth resistor R6 are grounded, the second end of the seventh resistor R7 is connected with the power supply, and the collector of the third triode Q3 is connected with the second end of the LED.
In this embodiment, the sampling voltage and the comparison voltage output by the sampling amplifying circuit 1 are connected to the comparator X3, the comparison voltage is the voltage of the sampling resistor R when the LED driving circuit is in an overcurrent state, and when the sampling voltage is greater than the comparison voltage, the comparator X3 can output a high level to stop the conduction of the third triode Q3, thereby achieving the cut-off of the LED driving circuit.
It can be understood that, in this embodiment, an MCU may also be added to process the sampled voltage, an input end of the MCU is connected to an output end of the sampling amplifying circuit, and an output end of the MCU is connected to an inverting input end of the comparator. Since the above embodiment describes the case of adding the MCU in detail, it is not described herein again.
On the basis of the above embodiment, in this embodiment, the method further includes: an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10;
the first end of the eighth resistor R8 is connected to the inverting input terminal of the comparator X3 and the output terminal of the sampling amplifying circuit 1, the second end of the eighth resistor R8 is grounded, the first end of the ninth resistor R9 and the first end of the tenth resistor R10 are commonly connected to the non-inverting input terminal of the comparator X3, the second end of the ninth resistor R9 is connected to the power supply, and the second end of the tenth resistor R10 is grounded.
In the embodiment, the eighth resistor, the ninth resistor and the tenth resistor are added to divide the voltage of the access comparator, so that the comparator is protected from being damaged.
The sampling amplifier circuit 1 in the above embodiment is briefly described, and the present embodiment provides a specific sampling amplifier circuit 1, as shown in fig. 1, where the sampling amplifier circuit 1 includes: a first operational amplifier X1, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth resistor R14;
a first end of the eleventh resistor R11 is connected to a first end of the sampling resistor R, a second end of the eleventh resistor R11 is connected to a first end of the twelfth resistor R12 and a non-inverting input end of the first operational amplifier X1, a first end of the thirteenth resistor R13 is connected to a second end of the sampling resistor R, a second end of the thirteenth resistor R13 is connected to an inverting input end of the first operational amplifier X1 and a first end of the fourteenth resistor R14, and a second end of the fourteenth resistor R14 is connected to an output end of the first operational amplifier X1, and the output ends are used as an output end of the sampling amplifier circuit 1.
In the present embodiment, the thirteenth resistor R13 and the fourteenth resistor R14 determine the amplification factor of the first operational amplifier X1, and the eleventh resistor R11 and the twelfth resistor R12 are symmetrical resistors of the thirteenth resistor R13 and the fourteenth resistor R14. The amplification factor of the first operational amplifier X1 is the fourteenth resistor R14 value/the thirteenth resistor R13 value.
In the embodiment, the voltage at two ends of the sampling resistor is sampled and amplified through the first operational amplifier, so that the current of the LED driving circuit is detected.
In specific implementation, in order to ensure accurate judgment of the overcurrent condition, the voltage across the sampling resistor R needs to be amplified in multiple stages. Therefore, as shown in fig. 1, in the present embodiment, the sampling amplification circuit 1 further includes: a second operational amplifier X2, a fifteenth resistor R15, a sixteenth resistor R16 and a seventeenth resistor R17;
a first end of the fifteenth resistor R15 is connected to the second end of the fourteenth resistor R14 and the output end of the first operational amplifier X1, a second end of the fifteenth resistor R15 is connected to the non-inverting input end of the second operational amplifier X2, a first end of the sixteenth resistor R16 and a first end of the seventeenth resistor R17 are commonly connected to the inverting input end of the second operational amplifier X2, a second end of the sixteenth resistor R16 is grounded, and a second end of the seventeenth resistor R17 is connected to the output end of the second operational amplifier X2, and are commonly used as the output end of the sampling amplifier circuit 1.
In the present embodiment, the sixteenth resistor R16 and the seventeenth resistor R17 determine the amplification factor of the second operational amplifier X2, which is (the value of the sixteenth resistor R16 + the value of the seventeenth resistor R17) </or is greater than or equal to >
A sixteenth resistance R16 value.
The LED driving circuit provided by this embodiment performs secondary amplification on the voltage at the two ends of the sampling resistor by adding the operational amplifier, so as to obtain a larger amplification factor.
In a specific implementation, in order to avoid damage to the LED due to an excessive power supply current connected to the LED driving circuit, in this embodiment, the method further includes: an eighteenth resistor R18;
the first end of the eighteenth resistor R18 is connected with the second end of the sampling resistor R and the first end of the thirteenth resistor R13, and the second end of the eighteenth resistor R18 is connected with the first end of the LED.
The eighteenth resistor in this embodiment is a current-limiting resistor to limit the current of the power supply connected to the LED driving circuit, thereby avoiding damaging the LED.
In the above embodiment, the sampled voltage output by the sampling amplifying circuit 1 will be accessed to the MCU3, but if the amplification factor of the sampled voltage is too large, the MCU3 will be damaged. Therefore, as shown in fig. 1, in the present embodiment, the method further includes: a nineteenth resistor R19;
a first end of the nineteenth resistor R19 is connected to the output end of the sampling amplifying circuit 1, and a second end of the nineteenth resistor R19 is connected to the input end of the MCU 3.
The nineteenth resistor in this embodiment is connected to the output terminal of the sampling amplification circuit and the input terminal of the MCU to prevent the sampling voltage from damaging the pin of the input terminal of the MCU.
The LED driving circuit provided in the present application is described in detail above. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.
It is further noted that, in the present specification, relational terms such as first and second, and the like are 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. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims (10)

1. An LED driving circuit, comprising:
the sampling amplifying circuit, the sampling resistor and the feedback control circuit;
the first end of the sampling resistor is connected with a power supply, the second end of the sampling resistor is connected with the first end of the LED, and the second end of the LED is connected with the feedback control circuit;
the sampling amplifying circuit is connected with the sampling resistor in parallel and is used for sampling and amplifying the voltage of the sampling resistor;
the sampling amplifying circuit is also connected with the feedback control circuit so as to control the on-off of the feedback control circuit according to the sampling voltage output by the sampling amplifying circuit and further control the on-off of the LED drive circuit.
2. The LED driving circuit of claim 1, wherein the feedback control circuit comprises: the circuit comprises a first triode, a second triode, a first resistor, a second resistor and a third resistor;
the base of first triode is connected the output of sampling amplifier circuit with the first end of first resistance, the projecting pole of first triode with the second end ground connection of first resistance, the collecting electrode of first triode is connected the first end of second resistance with the first end of third resistance and the base of second triode, the second end of second resistance is connected the power, the second end of third resistance with the projecting pole ground connection of second triode, the collecting electrode of second triode is connected the second end of LED.
3. The LED driving circuit according to claim 2, further comprising: MCU;
the input end of the MCU is connected with the output end of the sampling amplifying circuit, the output end of the MCU is connected with the base electrode of the first triode so as to compare the received sampling voltage with the threshold value, and when the sampling voltage exceeds the threshold value, a control signal is output to the base electrode of the first triode so as to cut off the LED driving circuit.
4. The LED driving circuit according to claim 3, further comprising: a fourth resistor and a fifth resistor;
the first end of the fourth resistor is connected with the output end of the MCU, the second end of the fourth resistor is connected with the base of the first triode and the first end of the first resistor, the first end of the fifth resistor is connected with the collector of the first triode and the first end of the second resistor, and the second end of the fifth resistor is connected with the base of the second triode and the first end of the third resistor.
5. The LED driving circuit of claim 1, wherein the feedback control circuit comprises: the third triode, the comparator, a sixth resistor and a seventh resistor;
the in-phase input end of the comparator is connected with the comparison voltage, the reverse input end of the comparator is connected with the output end of the sampling amplification circuit, the output end of the comparator is connected with the first end of the sixth resistor, the first end of the seventh resistor and the base of the third triode, the emitting electrode of the third triode is grounded with the second end of the sixth resistor, the second end of the seventh resistor is connected with the power supply, and the collector electrode of the third triode is connected with the second end of the LED.
6. The LED driving circuit according to claim 5, further comprising: an eighth resistor, a ninth resistor, and a tenth resistor;
the first end of the eighth resistor is connected with the inverting input end of the comparator and the output end of the sampling amplifying circuit, the second end of the eighth resistor is grounded, the first end of the ninth resistor and the first end of the tenth resistor are connected with the non-inverting input end of the comparator in common, the second end of the ninth resistor is connected with the power supply, and the second end of the tenth resistor is grounded.
7. The LED driving circuit according to any one of claims 1 to 6, wherein the sampling amplification circuit comprises: the first operational amplifier, the eleventh resistor, the twelfth resistor, the thirteenth resistor and the fourteenth resistor;
the first end of the eleventh resistor is connected with the first end of the sampling resistor, the second end of the eleventh resistor is connected with the first end of the twelfth resistor and the non-inverting input end of the first operational amplifier, the first end of the thirteenth resistor is connected with the second end of the sampling resistor, the second end of the thirteenth resistor is connected with the inverting input end of the first operational amplifier and the first end of the fourteenth resistor, and the second end of the fourteenth resistor is connected with the output end of the first operational amplifier to be used as the output end of the sampling amplifying circuit.
8. The LED driving circuit according to claim 7, wherein the sampling amplification circuit further comprises: the second operational amplifier, a fifteenth resistor, a sixteenth resistor and a seventeenth resistor;
a first end of the fifteenth resistor is connected to a second end of the fourteenth resistor and an output end of the first operational amplifier, a second end of the fifteenth resistor is connected to a non-inverting input end of the second operational amplifier, a first end of the sixteenth resistor and a first end of the seventeenth resistor are connected to an inverting input end of the second operational amplifier, a second end of the sixteenth resistor is grounded, and a second end of the seventeenth resistor and an output end of the second operational amplifier are connected to serve as an output end of the sampling amplifying circuit.
9. The LED driving circuit according to claim 8, further comprising: an eighteenth resistor;
and the first end of the eighteenth resistor is connected with the second end of the sampling resistor and the first end of the thirteenth resistor, and the second end of the eighteenth resistor is connected with the first end of the LED.
10. The LED driving circuit according to claim 3, further comprising: a nineteenth resistor;
and the first end of the nineteenth resistor is connected with the output end of the sampling amplification circuit, and the second end of the nineteenth resistor is connected with the input end of the MCU.
CN202210333420.6A 2022-03-31 2022-03-31 LED drive circuit Pending CN114845438A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210333420.6A CN114845438A (en) 2022-03-31 2022-03-31 LED drive circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210333420.6A CN114845438A (en) 2022-03-31 2022-03-31 LED drive circuit

Publications (1)

Publication Number Publication Date
CN114845438A true CN114845438A (en) 2022-08-02

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ID=82563940

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210333420.6A Pending CN114845438A (en) 2022-03-31 2022-03-31 LED drive circuit

Country Status (1)

Country Link
CN (1) CN114845438A (en)

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