CN113038655A

CN113038655A - LED lamp control circuit with adjustable luminance

Info

Publication number: CN113038655A
Application number: CN202110390667.7A
Authority: CN
Inventors: 汪菊琴; 刘培林; 刘德强; 李萍; 潘健
Original assignee: Wuxi Institute of Technology
Current assignee: Wuxi Institute of Technology
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2021-06-25
Anticipated expiration: 2041-04-12
Also published as: CN113038655B

Abstract

The invention discloses an LED lamp control circuit with adjustable brightness, which comprises a power supply detection module, an ambient light identification module, a signal delay and latch module and an output module. The brightness-adjustable LED lamp control circuit of the present invention controls the brightness of the LED bulb when it is lit by detecting the intensity of ambient light, which can effectively avoid the discomfort caused to the human eye caused by the bright LED bulb being turned on in a dark environment. After the human eye adapts for 1 to 2 minutes, the brightness of the LED bulb reaches normal brightness.

Description

LED lamp control circuit with adjustable luminance

Technical Field

The invention belongs to the field of household LED lighting control modes, and particularly relates to an LED lamp control circuit with adjustable brightness.

Background

When a person goes from a dark place to a bright place, the eyes have adaptation time of about 2 minutes to the strong light; especially, when the user wakes up at night, the light is suddenly turned on, if the light is too bright, the user can feel uncomfortable, such as dizziness, eyes cannot be opened, and the uncomfortable feeling can be greatly reduced if the light is dark. The brightness of the LED lamp bulbs on the current market is brighter, and the brightness reaches the brightest immediately after the LED lamp bulbs are electrified without a gradual brightening process. When the LED bulb is used in a bedroom, particularly when the lamp is turned on at night, strong light can cause eyes to have strong discomfort.

Chinese patent application publication No. CN112512170A discloses an LED lamp control circuit, an LED driving device, and a driving control method, where the LED lamp control circuit includes: analog signal conversion unit, output current computational element, error amplification unit and drive arrangement, wherein: the input end of the analog signal conversion unit is used for inputting the dimming signal and is suitable for calculating the PWM dimming signal to obtain an analog reference control signal representing the dimming brightness; the output current calculation unit is used for calculating a sampling signal obtained by sampling the LED current to obtain an equivalent current signal representing the LED current; the first input end of the error amplifying unit is coupled with the output end of the analog signal conversion unit, and the second input end of the error amplifying unit is coupled with the output end of the output current calculating unit to generate an error voltage; and a driving device, one end of which inputs the error voltage, generates a driving signal according to the error voltage and outputs the driving signal. The situation that the LED lamp flashes can be avoided by the scheme. However, the control circuit does not solve the problem that in a dark environment, the light is too strong at the moment when the LED bulb is powered on, which causes discomfort to human eyes.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present invention aims to: the LED lamp control circuit with adjustable brightness is provided, and the problem that the human eyes are uncomfortable due to the fact that the LED lamp bulb is too bright instantly when the lamp is turned on in a dark environment is solved; meanwhile, when the ambient light is strong, the brightness of the LED bulb can reach the strongest at the moment of turning on the lamp, and the normal application is not influenced.

In order to achieve the purpose, the invention provides the following technical scheme:

a brightness-adjustable LED lamp control circuit comprises a power supply detection module, an ambient light identification module, a signal delay and latch module and an output module;

the power supply detection module comprises a power supply detection unit and a delay unit;

the environment light ray identification module comprises a visible light sensor, an input signal filtering and amplifying processing unit, a first reference voltage, a first comparator and a second comparator; after being processed by the input signal filtering and amplifying processing unit, the signal sent by the visible light sensor is respectively connected with the positive input ends of the first comparator and the second comparator; the two paths of output reference potentials of the first reference voltage are connected with the negative input ends of the first comparator and the second comparator;

the signal delay and latch module comprises a first latch, a second latch, a decoder, a first delay unit, a second delay unit, a third latch, a fourth latch and a first sum gate; the decoder comprises a first inverter, a second inverter, a first AND gate, a second AND gate and a third AND gate; the first latch receives an output signal of the first comparator, and the second latch receives an output signal of the second comparator; the signals in the first latch and the second latch are decoded by the decoder and then are respectively connected with the first delay unit through the first AND gate, the second delay unit through the second AND gate, and the third AND gate is directly connected with the first AND gate;

the output module consists of a second reference voltage, a first switch, a second switch, a third switch, an amplifier, a resistor, a field effect tube and an LED bulb; the first switch is connected with the first delay unit and is controlled by the first delay unit; the second switch is connected with the second delay unit and is controlled by the second delay unit; the third switch is connected with the first sum gate and is controlled by the first sum gate; the input ends of the first switch, the second switch and the third switch are respectively connected with three reference potentials of the second reference voltage, and the output ends of the first switch, the second switch and the third switch are connected together and connected to the positive input end of the amplifier; the output end of the amplifier is connected with the grid electrode of the field effect tube, the source electrode of the field effect tube is connected with the resistor and the negative input end of the amplifier, and the drain electrode of the field effect tube is connected with the LED bulb.

Preferably, the power supply detection module is configured to compare the first comparator with the second comparator when the power supply is powered on; and/or, for clearing the latch; and/or controlling the delay working time of the output module relative to the power-on time.

Preferably, a third reference voltage and a third comparator are added to the first reference voltage, and the third reference voltage is compared with the first reference voltage through the third comparator; the compared signal is stored in the third latch.

Preferably, a fourth reference voltage and a fourth comparator are added to the first reference voltage, and the fourth reference voltage is compared with the first reference voltage through the fourth comparator; the compared signal is stored in a fourth latch.

The working principle is as follows: when the lamp is turned on, the intensity of ambient light is detected through the visible light sensor, the brightness of the LED lamp bulb when the LED lamp bulb is turned on is controlled according to the detection result, and after a period of adaptation, the normal brightness of the LDO lamp bulb is finally achieved.

Dividing the intensity of the ambient light detected by the visible light sensor into 3-5 gears, and defining the 1 st gear as the weakest ambient light; the 3 rd gear to the 5 th gear are the strongest in ambient light.

Supposing that the intensity of ambient light is divided into 3 gears, the ambient light is darker when the lamp is turned on and is in the 1 st gear, and the brightness of the LED bulb when the LED bulb is turned on is controlled to be 20% of the normal brightness; delaying for about 30 seconds to 40 seconds, and improving the brightness of the LED bulb to 50% of the normal brightness; and delaying for about 30 seconds to 40 seconds to reach normal brightness. If the intensity of the ambient light is in the 2 nd gear when the lamp is turned on, the brightness of the LED lamp when the lamp is turned on is set to be 50% of the normal brightness, the delay is about 30 seconds to 40 seconds, and the brightness reaches the normal brightness. If the intensity of the ambient light is stronger when the lamp is turned on and is positioned at the 3 rd gear, the brightness when the LED bulb is lightened is set to be the normal brightness.

Assuming that the intensity of ambient light is divided into 4 gears, the brightness of the LED bulb in the 1 st gear is controlled to be 10% of the normal brightness, the brightness in the 2 nd gear is 30% of the normal brightness, the brightness in the 3 rd gear is 60% of the normal brightness, and the brightness in the 4 th gear is the normal brightness; the switching time between every two gears is about 15 seconds to 25 seconds.

Assuming that the intensity of ambient light is divided into 5 steps, the brightness of the LED bulb in the 1 st step is controlled to be 10% of the normal brightness, the brightness in the 2 nd step is 25% of the normal brightness, the brightness in the 3 rd step is 50% of the normal brightness, the brightness in the 4 th step is 75% of the normal brightness, and the brightness in the 5 th step is the normal brightness; the switching time between every two gears is about 10 seconds to 20 seconds.

Compared with the prior art, the invention has the beneficial effects that:

luminance when the LED bulb is lighted through the intensity control that detects environment light can effectively avoid turning on under the dark surrounds LED bulb too bright uncomfortable that causes the people's eye. After the human eyes are adapted for 1-2 minutes, the brightness of the LED bulb reaches normal brightness, and the LED bulb is more suitable for places which are often turned on at night, such as bedrooms.

Drawings

In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive efforts.

Fig. 1 is a circuit diagram of a control circuit of a 3-step LED lamp in the present embodiment;

FIG. 2 is a timing diagram of the control of the LED bulb in the 1 st gear position and in the 3 rd gear position;

FIG. 3 is a timing diagram of the control of the LED bulb in the 2 nd gear position and in the 3 rd gear position;

FIG. 4 is a timing diagram of the control of the LED bulb in the 3 rd position;

fig. 5 is a circuit diagram of a 4-step LED lamp control circuit in the present embodiment;

FIG. 6 is a timing diagram of the control of the LED bulb in 4-gear position at the 1 st gear position;

FIG. 7 is a circuit diagram of a 5-position LED lamp control circuit;

fig. 8 is a timing chart of the control of the 5-position LED light bulb in the 1 st position.

101, a visible light sensor; 102. an electric signal filtering and amplifying processing unit; 110. a power supply detection and delay unit; 201. a first reference voltage; 202. a first comparator; 203. a second comparator; 204. a third comparator; 205. a fourth comparator; 301. a first latch; 302. a second latch; 303. a fifth latch; 304. a seventh latch; 401. a first delay unit; 402. a second delay unit; 403. a third delay unit; 404. a delay unit 4; 501. a third latch; 502. a fourth latch; 503. a sixth latch; 504. an eighth latch; 601. a second reference voltage; 701. an amplifier.

Detailed Description

The technical solutions in the specific embodiments of the present invention will be clearly and completely described below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the schematic diagram of the 3-step LED control circuit includes four parts: the device comprises a power supply detection module, an ambient light recognition module, a signal delay and latch module and an output module.

The power supply detection module consists of a power supply detection and delay unit, and is connected with the filtering amplification processing unit, all latches and the output end amplifier. The signal of the controller is used for controlling the input signal of the visible light sensor to be compared with the second comparator of the first comparator when the power supply is electrified, clearing all latches and controlling the output module to work after the power supply is electrified.

The environment light ray identification module consists of a visible light sensor, an input signal filtering and amplifying processing unit, a first reference voltage, a first comparator and a second comparator; the signal of the visible light sensor is connected with the positive input ends of the first comparator and the second comparator after being filtered and amplified; two paths of output reference potentials of the first reference voltage are connected with negative input ends of the first comparator and the second comparator.

The signal delay and latch module consists of a first latch, a second latch, a decoder, a first delay unit, a second delay unit, a third latch, a fourth latch and a first AND gate, wherein the decoder comprises a first inverter, a second inverter, a first AND gate, a second AND gate and a third AND gate. The first latch receives an output signal of the first comparator, and the second latch receives an output signal of the second comparator; the signals in the first latch and the second latch are decoded by a decoder, a first AND gate of the first latch and the second latch is connected with a first delay unit, a second AND gate of the second latch and the third AND gate are directly connected with a first AND gate. After the first delay unit finishes delaying, the signal is latched in a third latch, and the third latch transmits the signal to a second delay unit; after the delay of the second delay unit is finished, the signal is latched in the fourth latch, and the fourth latch transmits the signal to the first sum gate.

The output module is composed of a second reference voltage, a first switch, a second switch, a third switch, an amplifier, a resistor R1, a field effect tube M1 and an LED bulb. The first switch is connected with the first delay unit and is controlled by the first delay unit; the second switch is connected with the second delay unit and is controlled by the second delay unit; the third switch is connected with the first sum gate and is controlled by the first sum gate; the input ends of the first switch, the second switch and the third switch are respectively connected with three reference potentials of a second reference voltage 3, and the output ends of the first switch, the second switch and the third switch are connected together and connected to the positive input end of the amplifier; the output end of the amplifier is connected with the grid electrode of the field effect transistor M1, the source electrode of the M1 is connected with the resistor R1 and the negative input end of the amplifier, and the drain electrode of the M1 is connected with the LED bulb.

The specific control process is as follows:

v1 is the voltage of the electric signal generated by the visible light sensor after filtering and amplifying; v2 is voltage detected and delayed by the power supply for a period of time, and has the functions of waiting for the visible light sensor to convert the intensity of ambient light into an electric signal, filtering and amplifying the electric signal and the like after the LED bulb is electrified; secondly, clearing the first latch/12/21/22 and the first delay unit/2 to avoid misoperation caused by power-on; and the amplifier is turned off so as to prevent the judgment of the visible light sensor from being interfered by the transient flicker phenomenon.

VREF11 and VREF12 are two reference voltages generated by the first reference voltage, and are used to determine the voltage range of V1, so as to confirm the intensity range of the ambient light, and the voltage of VREF12 is higher than the voltage of VREF 11.

The first comparator compares the voltages of the V1 and the VREF11, when the voltage of V1 is less than the voltage of VREF11, it indicates that the intensity of the ambient light is weak, and the first comparator is in the 1 st gear, at this time, the output voltage V31 is 0, and the output voltage V32 of the second comparator is also 0; when V1 is greater than VREF11 voltage but less than VREF12 voltage, it indicates that the intensity of the ambient light is in the 2 nd position, and at this time, the output voltage V31 is high and the output voltage V32 is 0; when V1 is greater than VREF12, indicating strong intensity of ambient light, in the 3 rd gear, the output voltages V31 and V32 are both high.

When the power detect delay is over, V2 transitions from 0 to high and latches the V31 and V32 signals into the first latch and the second latch, respectively. The first inverter, I2, and the first and gate, NA2, NA3 decode the signal stored in the first latch 12 into three signals, V41, V42, and V43. When V31 and V32 are 0, V41 is high and V42 and V43 are 0; when V31 is high, V32 is 0, V42 is high, and V41 and V43 are 0; when V31 and V32 are both high, V43 is high and V41 and V42 are 0.

V51 and V52 are delay signals of 30 seconds to 40 seconds and respectively control the first switch and the second switch, when V51 is high, K1 is conducted, and when V53 is high, the second switch is conducted; v55 is the control signal when the LED bulb is normally on, and the third switch is on when the LED bulb is high. Only one of V51, V53 and V55 is high at the same time, so that only one of K1, the second switch and the third switch is turned on at the same time. VREF21, VREF22, VREF23 are output signals of the second reference voltage, wherein VREF23 is a control voltage when the LED bulb is normally on, VREF21 is 20% of VREF23, and VREF22 is 50% of VREF 23.

Assuming that V41 is a high signal and V42 and V43 are 0 signals, V51 will remain high for 30 seconds to 40 seconds, K1 is turned on, and the second switch and the third switch are turned off. After the delay is over, V51 changes from high to 0, the third latch will latch this state, and its output signal V52 changes from 0 to high, and the output signal V53 of the second delay cell also changes from 0 to high, while the second switch is turned on and K1 is turned off. V53 changes from high to 0 after delaying for 30-40 seconds, the fourth latch latches the state, the output signal V54 changes from 0 to high, the output signal V55 of the first and gate changes from 0 to high, the third switch is turned on, and the second switch is turned off; the V55 signal will remain high until power is removed.

The voltage of the resistor R1 is controlled by the output signals VREF3 of the K1, the second switch and the third switch through the amplifier and the field effect transistor M1, so that the current of R1 is controlled, and the current of R1 is the current of the LED bulb. When the LED bulb works normally, the third switch is turned on, VREF3 is equal to VREF23, and the LED current is equal to VREF 23/R1; when K1 is on, VREF3 is equal to VREF21, about 20% of VREF23, and the LED current is about 20% of the normal on current; when the second switch is on, VREF3 is equal to VREF22, which is approximately 50% of VREF23, and the LED current is approximately 50% of the normal on current.

The working process is as follows:

when the ambient light is dark and is in the 1 st gear, the working process is as shown in fig. 2:

when the power supply is powered on, the power supply detection unit detects that the power supply is larger than a set value, the delay time is calculated, meanwhile, the visible light sensor starts to detect the intensity of ambient light and converts the intensity of the ambient light into an electric signal, a signal V1 is obtained through filtering and amplifying processing, the signal V1 is compared with a first reference voltage 1/12 through a first comparator/2, and since V1 is smaller than VREF11, the obtained signal V31 is 0, and V32 is 0. After the power supply detection unit delays, the signals of V31 and V32 are respectively latched into the first latch and the second latch, meanwhile, the filtering amplification processing unit stops working, and then the signals in the first latch and the second latch cannot be influenced no matter how the ambient light changes until power is cut off and power is re-powered on next time. After the first inverter/I2 and the first and gate/NA 2/NA3 decode the first latch/12, V41 is high, V42 is 0, and V43 is 0. V51 changes from 0 to high, and the first switch is turned on, VREF3 is equal to VREF21, the LED lamp starts to work, the current of the LED lamp is about 20% of the current in normal work, the brightness is dark, and people cannot feel dazzling. After the first delay unit delays for 30 seconds to 40 seconds, V51 changes from high to 0, and simultaneously latches a signal into a third latch, V53 changes from 0 to high, a second switch is turned on, VREF3 is equal to VREF22, LED lamp current rises from 20% to 50% of current in normal operation, and the brightness of the lamp cannot be dazzled by the adaptation time of 30 seconds to 40 seconds before. The second delay unit delays for 30 seconds to 40 seconds again, then the V53 changes from high to 0, simultaneously latches the signal into the fourth latch, and outputs a V55 signal through the first AND gate, the V55 changes from 0 to high, the switch 3 is turned on, VREF3 is equal to VREF23, the LED bulb current is switched to the current in normal operation, and due to the adaptation of two kinds of dark light rays of 60 seconds to 80 seconds by human eyes, the strong light rays in the normal operation can be adapted quickly.

When the ambient light is in the 2 nd gear, the working process is as shown in fig. 3:

when the power supply is powered on, the power supply detection unit detects that the power supply is larger than a set value, the delay time is started to be calculated, meanwhile, the visible light sensor starts to detect the intensity of ambient light and converts the intensity of the ambient light into an electric signal, a signal V1 is obtained through filtering and amplifying processing, V1 is compared with a first reference voltage 1/12 through a first comparator/2, and since V1 is larger than VREF11 and smaller than VREF12, the obtained signal V31 is changed from 0 to high, and V32 is equal to 0. After the power supply detection unit delays, the signals of V31 and V32 are respectively latched into the first latch and the second latch, meanwhile, the filtering amplification processing unit stops working, and then the signals in the first latch and the second latch cannot be influenced no matter how the ambient light changes until power is cut off and power is re-powered on next time. After the first inverter/I2 and the first and gate/NA 2/NA3 decode the latch 1/2, V41 becomes 0, V42 becomes high, and V43 becomes 0. V51 remains at 0, V53 goes from 0 to high while the second switch is turned on, VREF3 is equal to VREF22, and the LED bulb starts to operate at a current of about 50% of the current in normal operation, at which time the brightness of the LED is not too glaring. After the second delay unit delays for 30 seconds to 40 seconds, V53 changes from high to 0, simultaneously, a signal is latched into a fourth latch, V55 changes from 0 to high, a third switch is turned on, VREF3 is equal to VREF23, LED bulb current is switched to current in normal work, and human eyes adapt to the light for 30 seconds to 40 seconds, so that the LED bulb can adapt to stronger light quickly.

The ambient light is stronger in the 3 rd gear, and the working process is as shown in fig. 4: after the power supply is powered on, when the power supply detection unit detects that the power supply is larger than a set value, the delay time starts to be calculated, meanwhile, the visible light sensor starts to detect the intensity of ambient light and converts the intensity of the ambient light into an electric signal, filtering and amplifying are carried out to obtain a signal V1, the signal V1 is compared with a first reference voltage 1/12 through a first comparator/2, and since V1 is larger than VREF12, the obtained signals V31 and V32 are both changed from 0 to high. After the power supply detection unit delays, the signals of V31 and V32 are respectively latched into the first latch and the second latch, meanwhile, the filtering amplification processing unit stops working, and then the signals in the first latch and the second latch cannot be influenced no matter how the ambient light changes until power is cut off and power is re-powered on next time. After the first inverter/I2 and the first and gate/NA 2/NA3 decode the latch 1/2, V41 becomes 0, V42 becomes 0, and V43 becomes high. V51 and V53 keep 0, and V55 changes from 0 to high, and the third switch is turned on at the same time, VREF3 is equal to VREF23, and the LED lamp begins to work normally, and normal use of people is not affected.

Fig. 5 and 6 show a 4-position LED lamp control circuit and a control timing sequence of an LED bulb when ambient light is dark (position 1). Compare with 3 gears LED lamp control circuit, can distinguish more meticulous ambient light to and under darker ambient light, the meeting of light change is softer when the LED bulb is lighted.

The 4-gear LED lamp control circuit adding part comprises that the first reference voltage is added by a first reference voltage 3, and the third reference voltage is compared with the V1 through a third comparator; the compared signal is stored in a fifth latch; the decoding circuit is additionally provided with a third inverter and a third AND gate; the third delay unit is used for delaying the decoded signal and storing the signal in the sixth latch; the reference circuit VREF2 increases a second reference voltage 4, and when the LED lamp normally works, K4 is turned on, K1, the second switch and the third switch are turned off.

Fig. 7 and 8 show a control circuit of the 5-position LED lamp and a control timing sequence of the LED bulb when the ambient light is dark (position 1). Compared with the 4-gear LED lamp control circuit, the 5-gear LED lamp control circuit adds a part comprising that the first reference voltage is increased by a fourth reference voltage, and VREF14 is compared with V1 through a fourth comparator; the compared signal is stored in a seventh latch; the decoding circuit is additionally provided with an inverter I4 and an AND gate NA 5; the delay unit 4 is used for delaying the decoded signal and is stored in the eighth latch; the reference circuit VREF2 increases a second reference voltage 5, and when the LED lamp normally works, K5 is turned on, K1, the second switch, the third switch, and K4 are turned off.

The present invention provides a brightness adjustable LED lamp control circuit, which is described in detail above, and the structure and the operation principle of the present invention are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the method and the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. An LED lamp control circuit with adjustable brightness, characterized in that, comprising a power supply detection module, an ambient light identification module, a signal delay and latch module and an output module;

The power detection module includes a power detection unit and a delay unit;

The ambient light recognition module includes a visible light sensor, an input signal filtering and amplifying processing unit, a first reference voltage, a first comparator and a second comparator; wherein the signal sent by the visible light sensor passes through the input signal filtering and amplifying processing unit After processing, they are respectively connected to the positive input terminals of the first comparator and the second comparator; the two output reference potentials of the first reference voltage are connected to the first comparator and the second comparator. connected to the negative input terminal;

The signal delay and latch module includes a first latch, a second latch, a decoder, a first delay unit, a second delay unit, a third latch, a fourth latch, a first and gate; wherein, the decoder includes a first inverter, a second inverter, a first AND gate, a second AND gate, a third AND gate; the first latch receives the first comparator The second latch receives the output signal of the second comparator; the signals in the first latch and the second latch are decoded by the decoder and respectively pass through the The first AND gate is connected to the first delay unit, the second AND gate is connected to the second delay unit, and the third AND gate is directly connected to the first AND gate;

The output module is composed of a second reference voltage, a first switch, a second switch, a third switch, an amplifier, a resistor, a field effect transistor, and an LED bulb; the first switch is connected to the first delay unit and is subjected to the first delay unit is controlled; the second switch is connected to the second delay unit and is controlled by the second delay unit; the third switch is connected to the first sum gate and is controlled by the first sum gate control; the input terminals of the first switch, the second switch and the third switch are respectively connected with the three reference potentials of the second reference voltage, and the output terminals are connected together and connected to the positive input terminal of the amplifier; The output end of the amplifier is connected to the grid of the field effect transistor, the source electrode of the field effect transistor is connected to the resistor and the negative input end of the amplifier, and the drain electrode of the field effect transistor is connected to the LED bulb.

2. The LED lamp control circuit with adjustable brightness according to claim 1, wherein the power detection module is used to compare the first comparator and the second comparator when the power is powered on; and/or , used to clear the latch; and/or control the delay working time of the output module relative to the power-on time.

3. The LED lamp control circuit with adjustable brightness according to claim 1 or 2, wherein a third reference voltage and a third comparator are added to the first reference voltage, and the third reference The voltage is compared with the first reference voltage through a third comparator; the compared signal is stored in the third latch.

4. The LED lamp control circuit with adjustable brightness according to claim 3, wherein a fourth reference voltage and a fourth comparator are added to the first reference voltage, and the fourth reference voltage is the same as the The first reference voltage is compared by the fourth comparator; the compared signal is stored in the fourth latch.