CN112261757A - LED control circuit and LED control method of passive dimming signal - Google Patents

LED control circuit and LED control method of passive dimming signal Download PDF

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CN112261757A
CN112261757A CN202011050087.5A CN202011050087A CN112261757A CN 112261757 A CN112261757 A CN 112261757A CN 202011050087 A CN202011050087 A CN 202011050087A CN 112261757 A CN112261757 A CN 112261757A
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voltage
resistor
comparator
input end
circuit
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CN112261757B (en
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区志杨
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Foshan Huaquan Technology Co Ltd
Guangdong Cnl Optoelectronics Technology Co ltd
FOSHAN HUAQUAN ELECTRICAL LIGHTING CO LTD
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Foshan Huaquan Technology Co Ltd
Guangdong Cnl Optoelectronics Technology Co ltd
FOSHAN HUAQUAN ELECTRICAL LIGHTING CO LTD
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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]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • 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]
    • H05B45/10—Controlling the intensity of the light
    • 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
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • H05B47/165—Controlling the light source following a pre-assigned programmed sequence; Logic control [LC]
    • 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
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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Abstract

The invention discloses an LED control circuit of a passive dimming signal, which comprises a power supply circuit, a dimming circuit, an LED circuit, a master control triode, a dimming setting circuit and/or a voltage regulating setting circuit, wherein the power supply circuit is connected with the dimming circuit; the dimming circuit comprises a coupler, a comparator and an integrator, wherein the coupler is used for detecting a PWM signal, the comparator is used for outputting a level signal to the integrator according to voltages of a reverse input end and a forward input end, and the integrator is used for controlling the state of the master control triode according to the level signal so as to adjust the LED circuit; the dimming setting circuit is used for driving the base electrode of the main control triode so that the base electrode of the main control triode has a preset saturated open state; the voltage regulating setting circuit is used for regulating the voltage of the reverse input end and the forward input end of the comparator according to the PWM signal. The invention also discloses an LED control method based on the LED control circuit. By adopting the invention, the LED light source can be dimmed through the passive dimming signal, and the phenomenon of black touch is avoided.

Description

LED control circuit and LED control method of passive dimming signal
Technical Field
The present disclosure relates to LED control circuits, and particularly to an LED control circuit for passive dimming signals and an LED control method based on the LED control circuit.
Background
Pulse Width Modulation (PWM) is a very efficient technique for controlling analog circuits using the digital output of a microprocessor, and is widely used in many fields such as measurement, communication to power control and conversion, and LED lighting.
In the field of lighting, most of the PWM dimming in the market is stroboscopic dimming.
As shown in fig. 1, the principle of the existing PWM dimming-based LED control circuit is: and the PWM signal is converted into 0-10V analog dimming after passing through an integrating circuit. However, the circuit needs to set default brightness for starting, and when the dimming controller is in darkness and is damaged, the circuit is in a light-off state, so that a user cannot perform maintenance or other emergency treatment in a dark state.
Therefore, the existing LED control circuit cannot meet the requirements of users.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide an LED control circuit and an LED control method for passive dimming signals, which can dim an LED light source by the passive dimming signals, thereby avoiding the occurrence of a black-touch phenomenon.
In order to solve the technical problem, the invention provides an LED control circuit of a passive dimming signal, which comprises a power supply circuit, a dimming circuit, an LED circuit and a master control triode, and is characterized by further comprising a dimming setting circuit and/or a voltage regulating setting circuit; the dimming circuit comprises a coupler, a comparator and an integrator, wherein the input end of the coupler is connected with a PWM signal, the collector of the output end of the coupler is connected with the inverting input end of the comparator, the emitter of the output end of the coupler is grounded, the positive input end of the comparator is connected with a power supply, the output end of the comparator is connected with the positive input end of the integrator, the reverse input end and the output end of the integrator are connected with the base electrode of the master control triode, the collector electrode of the master control triode is connected with a power supply, the emitter of the master control triode is connected with the LED circuit, the coupler is used for detecting PWM signals, the comparator is used for outputting a level signal to the integrator according to the voltages of the reverse input end and the forward input end, the integrator is used for controlling the state of the master control triode according to the level signal so as to adjust the LED circuit; the power supply circuit is connected with the base electrode of the master control triode through the dimming setting circuit, and the dimming setting circuit is used for driving the base electrode of the master control triode so that the base electrode of the master control triode has a preset saturated open state; the emitting electrode of the output end of the coupler is grounded through the voltage-regulating setting circuit, the forward input end of the comparator is connected with the power supply through the voltage-regulating setting circuit, and the voltage-regulating setting circuit is used for regulating the voltages of the reverse input end and the forward input end of the comparator according to the PWM signal.
As an improvement of the above solution, the dimming setting circuit includes a first voltage dividing resistor group and a second voltage dividing resistor group connected in series; one end of the first voltage division resistor group is connected with a power supply, and the other end of the first voltage division resistor group is connected with the base electrode of the master control triode through a diode; one end of the second voltage-dividing resistor group is grounded, and the other end of the second voltage-dividing resistor group is connected with the base electrode of the master control triode through the diode.
As an improvement of the above scheme, the voltage regulation setting circuit comprises a rectifier diode, a charging capacitor bank, a regulation triode, a charging resistor, a discharging resistor, a leveling resistor, a voltage regulation resistor and a grounding resistor; the emitter of the regulation triode is grounded, the base of the regulation triode is connected with the emitter of the output end of the coupler through the voltage regulating resistor, the collector of the regulation triode is connected with one end of the discharging resistor, and the other end of the discharging resistor is connected with the power supply through the charging resistor, is grounded through the charging capacitor bank and is connected with the positive input end of the comparator through the rectifier diode; one end of the leveling resistor is connected with an emitting electrode at the output end of the coupler, and the other end of the leveling resistor is grounded; one end of the grounding resistor is connected with the reverse input end of the comparator, and the other end of the grounding resistor is grounded.
As an improvement of the above scheme, the charging capacitor bank includes a first charging capacitor and a second charging capacitor connected in parallel.
Correspondingly, the invention also provides an LED control method based on the LED control circuit, which comprises the following steps: the coupler detects the PWM signal in real time; when the coupler does not detect the PWM signal, the coupler is cut off, the voltage regulation setting circuit enables the voltage of the positive input end of the comparator to be higher than the voltage of the reverse input end in a charging mode, and the output end of the comparator outputs a high-level signal; when the coupler detects the PWM signal, the coupler is switched on and switched off according to the proportion of the PWM signal, wherein when the coupler is switched on, the voltage regulation setting circuit enables the voltage of the reverse input end of the comparator to be higher than the voltage of the forward input end in a discharging mode, the output end of the comparator outputs a low level signal, when the coupler is switched off, the voltage regulation setting circuit enables the voltage of the forward input end of the comparator to be higher than the voltage of the reverse input end in a charging mode, and the output end of the comparator outputs a high level signal; and the level signal output by the comparator is converted into an analog dimming voltage through the integrator, so that the master control triode performs dimming control on the LED circuit according to the PWM signal.
As an improvement of the above scheme, the voltage regulation setting circuit comprises a rectifier diode, a charging capacitor bank, a regulation triode, a charging resistor, a discharging resistor, a leveling resistor, a voltage regulation resistor and a grounding resistor; the emitter of the regulation triode is grounded, the base of the regulation triode is connected with the emitter of the output end of the coupler through the voltage regulating resistor, the collector of the regulation triode is connected with one end of the discharging resistor, and the other end of the discharging resistor is connected with the power supply through the charging resistor, is grounded through the charging capacitor bank and is connected with the positive input end of the comparator through the rectifier diode; one end of the leveling resistor is connected with an emitting electrode at the output end of the coupler, and the other end of the leveling resistor is grounded; one end of the grounding resistor is connected with the reverse input end of the comparator, and the other end of the grounding resistor is grounded.
As an improvement of the above solution, the method for making the voltage of the reverse input end of the comparator higher than the voltage of the forward input end by the voltage regulating setting circuit through a discharging manner includes: when the coupler is conducted, the regulating triode is conducted to drive the charging capacitor bank to discharge through the discharging resistor, so that the voltage of the reverse input end of the comparator is higher than that of the forward input end.
As an improvement of the above solution, the method for making the voltage of the forward input end of the comparator higher than the voltage of the reverse input end by the voltage regulation setting circuit through a charging mode includes: when the coupler is cut off, the regulating triode is cut off to drive the charging capacitor bank to be charged through the charging resistor, so that the voltage of the forward input end of the comparator is higher than the voltage of the reverse input end.
As an improvement of the above scheme, when the output end of the comparator outputs a high level signal, the master control triode performs dimming control on the LED circuit according to the maximum set power.
As an improvement of the above scheme, the LED control method further includes: the dimming setting circuit carries out real-time voltage division processing on the power supply voltage; and the power supply voltage is output to the base electrode of the master control triode after voltage division treatment, so that the base electrode of the master control triode has a preset saturated switching-on state.
The implementation of the invention has the following beneficial effects:
the invention can be provided with a dimming setting circuit independently. The minimum saturation of the master control triode can be effectively adjusted by adjusting the voltage division effect of the dimming setting circuit, so that the LED circuit outputs different values as the minimum dimming value, the condition that the dimming is turned off due to the damage of a controller and artificial factors is avoided, the power supply can be turned on no matter the problem point after being electrified, and a series of reflection caused by the turning off of the lamp is avoided;
the invention can be provided with a voltage regulating setting circuit independently. The power supply carries out charging and discharging treatment on the voltage regulating setting circuit, so that the LED circuit can output 100% of power under the condition of no PWM signal, and the lamp-out state caused by the damage or signal interruption of the dimming controller is improved;
the invention can simultaneously set the dimming setting circuit and the voltage regulating setting circuit. The power can be output by 100% when no PWM signal exists, and the phenomenon of black touch under a certain specific environment is avoided; or the setting of minimum dimming is met, and the condition that the dimming is in a light-out state due to controller damage and artificial factors is avoided.
Drawings
FIG. 1 is a prior art LED control circuit diagram;
fig. 2 is a circuit diagram of a first embodiment of the LED control circuit of the passive dimming signal of the present invention;
FIG. 3 is a circuit diagram of a second embodiment of the LED control circuit for passive dimming signals of the present invention;
fig. 4 is a circuit diagram of a third embodiment of the LED control circuit of the passive dimming signal of the present invention;
FIG. 5 is a flow chart of a first embodiment of the LED control method based on the LED control circuit of the present invention;
fig. 6 is a flowchart of a second embodiment of the LED control method based on the LED control circuit according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
Referring to fig. 2, fig. 2 shows a first embodiment of the LED control circuit of the passive dimming signal according to the present invention, which includes a control power supply circuit E, a dimming circuit, an LED circuit G, a main control transistor Q1, and a dimming setting circuit H.
The dimming circuit includes a coupler U3, a comparator U2B, and an integrator U2A. Specifically, the method comprises the following steps:
the input end of the coupler U3 is connected with a PWM signal, and the coupler U3 is used for detecting the PWM signal and outputting voltage outwards according to the PWM signal;
the collector of the output end of the coupler U3 is connected with the inverting input end of the comparator U2B, the emitter of the output end of the coupler U3 is grounded, the forward input end of the comparator U2B is connected with a power supply VCC, the output end of the comparator U2B is connected with the forward input end of the integrator U2A, and the comparator U2B is used for outputting a level signal to the integrator U2A according to the voltages of the inverting input end and the forward input end;
the reverse input end and the output end of the integrator U2A are connected with the base electrode of the master control triode Q1, the collector electrode of the master control triode Q1 is connected with a power supply VCC, the emitter electrode of the master control triode Q1 is connected with the LED circuit G, and the integrator U2A is used for controlling the state of the master control triode Q1 according to the level signal so as to adjust the LED circuit G;
the power supply circuit E is connected with the base of the master control triode Q1 through the dimming setting circuit H, and the dimming setting circuit H is used for driving the base of the master control triode Q1 to enable the base of the master control triode Q1 to have a preset saturated turn-on state.
As shown in fig. 1, the dimming setting circuit H is not provided in the related art. In operation, the coupler U3 detects a PWM signal in real time, when the coupler U3 does not detect the PWM signal, the coupler U3 is turned off, the voltage at the reverse input end (i.e., voltage at point D) of the comparator U2B is higher than the voltage at the forward input end (i.e., voltage at point B), the output end of the comparator U2B outputs a low-level signal, and the low-level signal output by the comparator U2B is converted into a low-level output by the integrator U2A; at this time, the main control transistor Q1 is turned off, the LED circuit G does not output, and the brightness of the LED circuit G is 0. Therefore, in the prior art, the dimming ratio of the LED control circuit is (0 to 100%).
Unlike the prior art, in the present invention, a dimming setting circuit H is provided. In operation, the coupler U3 detects a PWM signal in real time, when the coupler U3 does not detect the PWM signal, the coupler U3 is turned off, the voltage at the reverse input end (i.e., voltage at point D) of the comparator U2B is higher than the voltage at the forward input end (i.e., voltage at point B), the output end of the comparator U2B outputs a low-level signal, and the low-level signal output by the comparator U2B is converted into a low-level output by the integrator U2A; meanwhile, the dimming setting circuit H divides voltage to drive the main control triode Q1, so that the main control triode Q1 has certain saturation and turn-on, the LED circuit G is lightened, and the brightness of the LED circuit G is preset saturation. Therefore, in the present invention, the dimming ratio of the LED control circuit is (preset saturation to 100%).
It should be noted that the minimum saturation of the main control transistor Q1 can be adjusted by adjusting the voltage dividing effect of the dimming setting circuit H, so that the LED circuit G outputs different values as the minimum dimming value.
Specifically, the dimming setting circuit H includes a first voltage dividing resistor group R13 and a second voltage dividing resistor group R14 connected in series with each other; one end of the first voltage-dividing resistor group R13 is connected with a power supply VCC, and the other end of the first voltage-dividing resistor group R13 is connected with the base electrode of the main control triode Q1 through a diode D1; one end of the second voltage-dividing resistor group R14 is grounded, and the other end is connected with the base of the master transistor Q1 through the diode D1. The first voltage-dividing resistor group R13 and the second voltage-dividing resistor group R14 can be formed by one or more resistors in series or parallel connection, and have unique structure and strong flexibility.
Therefore, when the integrator U2A outputs a low level, the main control transistor Q1 is driven by the additionally added first voltage-dividing resistor group R13 and second voltage-dividing resistor group R14 to divide the voltage, so that the main control transistor Q1 is turned on in a certain saturation state, and the LED circuit G is turned on; meanwhile, the resistance values of the first voltage-dividing resistor group R13 and the second voltage-dividing resistor group R14 can be adjusted to make the LED circuit G output different values, so that the LED circuit G can be used as the minimum dimming value, and the dimming ratio is (set value-100%).
Therefore, the dimming setting circuit H is arranged, any minimum dimming value can be flexibly set according to the requirement of a customer when no PWM signal exists, and the condition that the dimming is switched off due to the damage of a controller and artificial factors is avoided, so that the power supply can be switched on no matter the problem point is powered on, and a series of reflection caused by the switching off of the lamp is avoided.
Referring to fig. 3, fig. 3 shows a second embodiment of the LED control circuit of the passive dimming signal of the present invention, which is different from the first embodiment shown in fig. 2 in that only the voltage regulation setting circuit I is provided and the dimming setting circuit H is not provided. Coupler U3's output projecting pole passes through the voltage regulation sets up circuit I ground connection, and comparator U2B's forward input passes through voltage regulation sets up circuit I and connects the power VCC, voltage regulation sets up circuit I and is used for the basis the PWM signal adjusts the voltage of comparator U2B's reverse input and forward input.
As shown in fig. 1, the voltage regulation setting circuit I is not provided in the related art. In operation, the coupler U3 detects a PWM signal in real time, when the coupler U3 does not detect the PWM signal, the coupler U3 is turned off, the voltage at the reverse input end (i.e., voltage at point D) of the comparator U2B is higher than the voltage at the forward input end (i.e., voltage at point B), the output end of the comparator U2B outputs a low-level signal, and the low-level signal output by the comparator U2B is converted into a low-level output by the integrator U2A; at this time, the main control transistor Q1 is turned off, the LED circuit G does not output, the brightness of the LED circuit G is 0, and the LED circuit G is in the light-off mode. Therefore, in the prior art, the dimming ratio of the LED control circuit is (0 to 100%).
Different from the prior art, the invention is provided with a voltage regulation setting circuit I. At the moment the circuit is powered on, coupler U3 detects the PWM signal in real time.
(1) When the coupler U3 does not detect the PWM signal, the coupler U3 is turned off, the initial voltage of the inverting input terminal (i.e. the voltage at point D) of the comparator U2B is higher than the initial voltage of the forward input terminal (i.e. the voltage at point B), and the output terminal of the comparator U2B outputs a low level signal; meanwhile, the voltage regulation setting circuit I makes the voltage at the forward input end (i.e., the voltage at the point B) of the comparator U2B higher than the voltage at the reverse input end (i.e., the voltage at the point D) by charging, the level signal output by the output end of the comparator U2B is converted from low level to high level, and the high level signal output by the comparator U2B is converted into high level by the integrator U2A and is output; at this time, the main control triode Q1 is turned on, the LED circuit G outputs the maximum set power, and the brightness of the LED circuit G is 100%, thereby realizing 100% power output without the PWM dimming signal.
(2) When the coupler U3 detects the PWM signal, the coupler U3 turns on and off proportionally among the PWM signal. Specifically, when the coupler U3 is turned on, the voltage regulation setting circuit I makes the voltage at the reverse input end (i.e., voltage at point D) of the comparator U2B higher than the voltage at the forward input end (i.e., voltage at point B) by discharging, and the output end of the comparator U2B outputs a low level signal. When the coupler U3 is turned off, the voltage regulation setting circuit I charges the comparator U2B such that the voltage at the forward input end (i.e., the voltage at point B) is higher than the voltage at the reverse input end (i.e., the voltage at point D), so that the output end of the comparator U2B outputs a high level signal. Therefore, the circuit periodically makes the output end of the comparator U2B output high level and low level proportionally according to the PWM signal proportion, and in the dimming process, after the comparator U2B outputs a level signal according to the PWM signal proportion, the level signal is converted into an analog dimming voltage of 0-10V through the integrator U2A, so that the main control triode Q1 carries out dimming control on the LED circuit G according to the PWM signal.
In practical applications, when coupler U3 finds no PWM signal (within 0.3-0.6 seconds), the voltage regulator setting circuit I is charged by the power supply (within 0.6-0.8 seconds), so that the LED outputs 100% power, thereby improving the light-out condition caused by the dimmer controller being damaged or the signal being interrupted.
Specifically, the voltage regulation setting circuit I comprises a rectifier diode D3, a charging capacitor bank (C12, C13), a regulation and control triode Q6, a charging resistor R28, a discharging resistor R29, a leveling resistor R26, a voltage regulation resistor R27 and a grounding resistor R25; the emitter of the regulating triode Q6 is grounded, the base of the regulating triode Q6 is connected with the emitter of the output end of the coupler U3 through the voltage-regulating resistor R27, the collector of the regulating triode Q6 is connected with one end of the discharging resistor R29, the other end of the discharging resistor R29 is connected with a power supply VCC through a charging resistor R28, is grounded through a charging capacitor bank (C12, C13) and is connected with the positive input end of the comparator U2B through a rectifying diode D3; one end of the leveling resistor R26 is connected with an emitter of the output end of the coupler U3, and the other end of the leveling resistor R26 is grounded; one end of the grounding resistor R25 is connected with the reverse input end of the comparator U2B, and the other end is grounded.
Thus, at the instant the circuit is powered up, coupler U3 detects the PWM signal in real time.
(1) When the coupler U3 does not detect the PWM signal, the coupler U3 is turned off, the initial voltage of the inverting input terminal (i.e. the voltage at point D) of the comparator U2B is higher than the initial voltage of the forward input terminal (i.e. the voltage at point B), and the output terminal of the comparator U2B outputs a low level signal; meanwhile, the power supply charges the charging capacitor bank (C12, C13) through the charging resistor R28, the charging time is determined by the resistance value of the charging resistor R28, at this time, the voltage of the emitter at the output end of the coupler U3 (i.e., the voltage at the point a) is at a low level, the control triode Q6 is turned off, so that the voltage at the positive electrode of the rectifier diode D3 (i.e., the voltage at the point C) is equal to the power supply voltage after the charging capacitor bank (C12, C13) is fully charged, the voltage at the positive electrode of the rectifier diode D3 (i.e., the voltage at the point B) is higher than the voltage at the reverse input end (i.e., the voltage at the point D) after the positive electrode of the rectifier diode D3, the level signal output by the output end of the comparator U2B is converted from a low level to a high level, and the high level signal output by the comparator U2B is converted into; at this time, the main control triode Q1 is turned on, and the LED circuit G outputs the maximum set power, thereby realizing 100% power output without the PWM dimming signal.
(2) When the coupler U3 detects the PWM signal, the coupler U3 turns on and off proportionally among the PWM signal. Specifically, when the coupler U3 is turned on, the output end emitter voltage (i.e., voltage at point a) of the coupler U3 is converted into a high level, the level is determined by the resistance value of the leveling resistor R26, the output end emitter voltage (i.e., voltage at point a) of the coupler U3 turns on the regulating triode Q6 through the regulating resistor R27 according to the ratio of the PWM signal, the conduction of the regulating triode Q6 causes the charging capacitor bank (C12, C13) to discharge through the discharging resistor R29, the positive electrode voltage (i.e., voltage at point C) of the rectifying diode D3 is converted from the high level into the low level, the forward input end voltage (i.e., voltage at point B) of the comparator U2U 637 returns to the original state, meanwhile, the reverse input end voltage (i.e., voltage at point D) of the comparator U2B is higher than the forward input end voltage (i.e., voltage at point B), and the output end voltage 5392 of. When the coupler U3 is turned off, the control transistor Q6 is turned off, and the turn-off of the control transistor Q6 also enables the charging capacitor group (C12, C13) to be recharged by the charging resistor R28, after the charging capacitor group (C12, C13) is fully charged, the positive voltage (i.e., the voltage at point C) of the rectifier diode D3 flows through the voltage at the forward input end (i.e., the voltage at point B) of the comparator U2B through the rectifier diode D3, and after the voltage at the forward input end (i.e., the voltage at point B) of the comparator U2B is increased from the original initial state to the flat value, the voltage at the forward input end (i.e., the voltage at point B) of the comparator U2B is higher than the voltage at the reverse input end (i.e., the voltage at point D), so that the output end 2B.
In practical applications, when the coupler U3 finds no PWM signal (within 0.3-0.6 seconds), the power supply-to-charging capacitor bank (C12, C13) is fully charged (within 0.6-0.8 seconds), so that the LED outputs 100% power, thereby improving the light-out condition caused by the breakdown of the dimmer controller or signal interruption. Therefore, the invention can output 100% power without PWM signal, and the dimming ratio is (0-100%).
Further, the charging capacitor bank (C12, C13) includes a first charging capacitor C12 and a second charging capacitor C13 connected in parallel, but not limited thereto.
Referring to fig. 4, fig. 4 shows a third embodiment of the LED control circuit of the passive dimming signal of the present invention, which is different from the first embodiment shown in fig. 2 in that a dimming setting circuit H and a voltage regulating setting circuit I are provided in the present embodiment.
In the working process, the principle of the dimming setting circuit H is consistent with that of the embodiment, and the principle of the voltage regulating setting circuit I is consistent with that of the second embodiment. Through the combined action of the dimming setting circuit H and the voltage regulating setting circuit I, the power supply can output 100% of power when no PWM signal exists, and the dimming proportion is (set value-100%), so that the light-out state caused by the damage of a dimming controller or the interruption of a signal is improved, the condition that the light is dimmed to the light-out state caused by artificial factors can be avoided, and the power supply can light no matter which problem is caused after the power supply is electrified.
Referring to fig. 5, fig. 5 is a flowchart illustrating a first embodiment of the LED control method based on the LED control circuit according to the present invention.
The LED control circuit according to the present LED control method has a configuration as shown in fig. 3 and 4. Specifically, the LED control method comprises the following steps:
and S101, detecting the PWM signal in real time by the coupler.
S102, when the coupler does not detect the PWM signal, the coupler is cut off, the voltage regulating setting circuit enables the voltage of the positive input end of the comparator to be higher than the voltage of the negative input end in a charging mode, and the output end of the comparator outputs a high-level signal.
That is, when the coupler U3 does not detect the PWM signal, the coupler U3 is turned off, the initial voltage of the inverting input terminal of the comparator U2B (i.e., the voltage at point D) is higher than the initial voltage of the forward input terminal (i.e., the voltage at point B), and the output terminal of the comparator U2B outputs a low level signal; meanwhile, the voltage regulation setting circuit I charges the comparator U2B such that the voltage at the forward input end (i.e., the voltage at point B) is higher than the voltage at the reverse input end (i.e., the voltage at point D), the level signal output by the output end of the comparator U2B is converted from low level to high level, and the high level signal output by the comparator U2B is converted to high level by the integrator U2A and is output.
And S103, when the coupler detects the PWM signal, the coupler is switched on and off according to the proportion of the PWM signal, wherein when the coupler is switched on, the voltage regulation setting circuit enables the voltage of the reverse input end of the comparator to be higher than the voltage of the forward input end in a discharging mode, the output end of the comparator outputs a low level signal, when the coupler is switched off, the voltage regulation setting circuit enables the voltage of the forward input end of the comparator to be higher than the voltage of the reverse input end in a charging mode, and the output end of the comparator outputs a high level signal.
And S104, converting the level signal output by the comparator into an analog dimming voltage through an integrator so that the main control triode can carry out dimming control on the LED circuit according to the PWM signal.
Therefore, the circuit periodically makes the output end of the comparator U2B output high level and low level proportionally according to the PWM signal proportion, and in the dimming process, after the comparator U2B outputs a level signal according to the PWM signal proportion, the level signal is converted into an analog dimming voltage of 0-10V through the integrator U2A, so that the main control triode Q1 carries out dimming control on the LED circuit G according to the PWM signal.
Further, when the output end of the comparator outputs a high level signal, the master control triode performs dimming control on the LED circuit according to the maximum set power. Therefore, in practical applications, when coupler U3 finds no PWM signal (within 0.3-0.6 seconds), the voltage regulator circuit I is charged by the power supply (within 0.6-0.8 seconds), so that the LED outputs 100% power, thereby improving the light-out condition caused by the dimmer controller being damaged or the signal being interrupted.
As shown in fig. 3 and 4, the voltage regulation setting circuit I includes a rectifying diode D3, a charging capacitor bank (C12, C13), a control transistor Q6, a charging resistor R28, a discharging resistor R29, a leveling resistor R26, a voltage regulation resistor R27, and a grounding resistor R25; the emitter of the regulating triode Q6 is grounded, the base of the regulating triode Q6 is connected with the emitter of the output end of the coupler U3 through the voltage-regulating resistor R27, the collector of the regulating triode Q6 is connected with one end of the discharging resistor R29, the other end of the discharging resistor R29 is connected with a power supply through the charging resistor R28, is grounded through the charging capacitor bank (C12, C13) and is connected with the positive input end of the comparator U2B through the rectifying diode D3; one end of the leveling resistor R26 is connected with an emitter of the output end of the coupler U3, and the other end of the leveling resistor R26 is grounded; one end of the grounding resistor R25 is connected with the reverse input end of the comparator U2B, and the other end is grounded.
Specifically, the method for enabling the voltage at the reverse input end of the comparator to be higher than the voltage at the forward input end of the comparator in a discharging mode by the voltage regulating setting circuit comprises the following steps: when the coupler is conducted, the regulating triode is conducted to drive the charging capacitor bank to discharge through the discharging resistor, so that the voltage of the reverse input end of the comparator is higher than that of the forward input end.
That is to say, when the coupler U3 is turned on, the output end emitter voltage (i.e., voltage at point a) of the coupler U3 is converted to high level, the level is determined by the resistance value of the leveling resistor R26, the output end emitter voltage (i.e., voltage at point a) of the coupler U3 turns on the regulating triode Q6 through the regulating resistor R27 according to the ratio of the PWM signal, the conduction of the regulating triode Q6 causes the charging capacitor bank (C12, C13) to discharge through the discharging resistor R29, the positive electrode voltage (i.e., voltage at point C) of the rectifying diode D3 is converted from high level to low level, the forward input end voltage (i.e., voltage at point B) of the comparator U2U 637 returns to the original state, meanwhile, the reverse input end voltage (i.e., voltage at point D) of the comparator U2B is higher than the forward input end voltage (i.e., voltage at point B), and the output end voltage 5392 of.
Meanwhile, the method for enabling the voltage of the forward input end of the comparator to be higher than the voltage of the reverse input end of the comparator by the voltage regulating setting circuit in a charging mode comprises the following steps: when the coupler is cut off, the regulating triode is cut off to drive the charging capacitor bank to be charged through the charging resistor, so that the voltage of the forward input end of the comparator is higher than the voltage of the reverse input end.
That is, when the coupler U3 is turned off, the initial voltage (i.e., the voltage at point D) at the inverting input terminal of the comparator U2B is higher than the initial voltage (i.e., the voltage at point B) at the forward input terminal, and the output terminal of the comparator U2B outputs a low level signal; meanwhile, the power supply charges the charging capacitor bank (C12, C13) through the charging resistor R28, the charging time is determined by the resistance of the charging resistor R28, at this time, the voltage of the emitter at the output end of the coupler U3 (i.e., the voltage at the point a) is at a low level, the control transistor Q6 is turned off, so that the voltage at the positive electrode of the rectifier diode D3 (i.e., the voltage at the point C) is equal to the power supply voltage after the charging capacitor bank (C12, C13) is fully charged, the voltage at the positive electrode of the rectifier diode D3 (i.e., the voltage at the point B) is higher than the voltage at the reverse input end (i.e., the voltage at the point D) after the positive electrode of the rectifier diode D3 passes through the rectifier diode D3, the level signal output by the output end of the comparator U2B is converted from a low level to a high level, and the high level signal output by the comparator.
Therefore, the invention can output 100% power without PWM signal, and the dimming proportion is (0-100%), thereby improving the light-out state caused by the damage of the dimming controller or the interruption of the signal.
Referring to fig. 6, fig. 6 shows a flowchart of a second embodiment of the LED control method based on the LED control circuit according to the present invention.
Fig. 4 shows a configuration of an LED control circuit according to the present LED control method.
Specifically, the LED control method comprises the following steps:
and S201, detecting the PWM signal in real time by the coupler.
S202, when the coupler does not detect the PWM signal, the coupler is cut off, the voltage regulating setting circuit enables the voltage of the positive input end of the comparator to be higher than the voltage of the negative input end in a charging mode, and the output end of the comparator outputs a high-level signal.
S203, when the coupler detects the PWM signal, the coupler is switched on and switched off according to the proportion of the PWM signal, when the coupler is switched on, the voltage regulation setting circuit enables the voltage of the reverse input end of the comparator to be higher than the voltage of the forward input end in a discharging mode, the output end of the comparator outputs a low level signal, when the coupler is switched off, the voltage regulation setting circuit enables the voltage of the forward input end of the comparator to be higher than the voltage of the reverse input end in a charging mode, and the output end of the comparator outputs a high level signal.
And S204, converting the level signal output by the comparator into an analog dimming voltage through the integrator so that the main control triode performs dimming control on the LED circuit according to the PWM signal.
S205, the dimming setting circuit performs real-time voltage division processing on the power supply voltage;
and S206, outputting the power supply voltage to the base electrode of the main control triode after voltage division so that the base electrode of the main control triode has a preset saturated open state.
When the LED dimming circuit works, the dimming setting circuit H divides voltage to drive the main control triode Q1, so that the main control triode Q1 has certain saturation and is switched on, the LED circuit G is lightened, and the brightness of the LED circuit G is preset saturation. Therefore, in the present invention, the dimming ratio of the LED control circuit is (preset saturation to 100%). In addition, the minimum saturation of the main control transistor Q1 can be adjusted by adjusting the voltage dividing effect of the dimming setting circuit H, so that the LED circuit G outputs different values as the minimum dimming value.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. An LED control circuit of a passive dimming signal comprises a power supply circuit, a dimming circuit, an LED circuit and a master control triode, and is characterized by further comprising a dimming setting circuit and/or a voltage regulating setting circuit;
the dimming circuit comprises a coupler, a comparator and an integrator, wherein the input end of the coupler is connected with a PWM signal, the collector of the output end of the coupler is connected with the inverting input end of the comparator, the emitter of the output end of the coupler is grounded, the positive input end of the comparator is connected with a power supply, the output end of the comparator is connected with the positive input end of the integrator, the reverse input end and the output end of the integrator are connected with the base electrode of the master control triode, the collector electrode of the master control triode is connected with a power supply, the emitter of the master control triode is connected with the LED circuit, the coupler is used for detecting PWM signals, the comparator is used for outputting a level signal to the integrator according to the voltages of the reverse input end and the forward input end, the integrator is used for controlling the state of the master control triode according to the level signal so as to adjust the LED circuit;
the power supply circuit is connected with the base electrode of the master control triode through the dimming setting circuit, and the dimming setting circuit is used for driving the base electrode of the master control triode so that the base electrode of the master control triode has a preset saturated open state;
the emitting electrode of the output end of the coupler is grounded through the voltage-regulating setting circuit, the forward input end of the comparator is connected with the power supply through the voltage-regulating setting circuit, and the voltage-regulating setting circuit is used for regulating the voltages of the reverse input end and the forward input end of the comparator according to the PWM signal.
2. The LED control circuit of claim 1, wherein the dimming setting circuit comprises a first voltage dividing resistor group and a second voltage dividing resistor group connected in series with each other;
one end of the first voltage division resistor group is connected with a power supply, and the other end of the first voltage division resistor group is connected with the base electrode of the master control triode through a diode;
one end of the second voltage-dividing resistor group is grounded, and the other end of the second voltage-dividing resistor group is connected with the base electrode of the master control triode through the diode.
3. The LED control circuit of claim 1, wherein the voltage regulation setting circuit comprises a rectifier diode, a charge capacitor bank, a regulation triode, a charge resistor, a discharge resistor, a leveling resistor, a voltage regulation resistor, and a ground resistor;
the emitter of the regulation triode is grounded, the base of the regulation triode is connected with the emitter of the output end of the coupler through the voltage regulating resistor, the collector of the regulation triode is connected with one end of the discharging resistor, and the other end of the discharging resistor is connected with the power supply through the charging resistor, is grounded through the charging capacitor bank and is connected with the positive input end of the comparator through the rectifier diode;
one end of the leveling resistor is connected with an emitting electrode at the output end of the coupler, and the other end of the leveling resistor is grounded;
one end of the grounding resistor is connected with the reverse input end of the comparator, and the other end of the grounding resistor is grounded.
4. The LED control circuit of claim 3, wherein the set of charging capacitors comprises a first charging capacitor and a second charging capacitor connected in parallel with each other.
5. An LED control method based on the LED control circuit of any one of claims 1 to 4, comprising:
the coupler detects the PWM signal in real time;
when the coupler does not detect the PWM signal, the coupler is cut off, the voltage regulation setting circuit enables the voltage of the positive input end of the comparator to be higher than the voltage of the reverse input end in a charging mode, and the output end of the comparator outputs a high-level signal;
when the coupler detects the PWM signal, the coupler is switched on and switched off according to the proportion of the PWM signal, wherein when the coupler is switched on, the voltage regulation setting circuit enables the voltage of the reverse input end of the comparator to be higher than the voltage of the forward input end in a discharging mode, the output end of the comparator outputs a low level signal, when the coupler is switched off, the voltage regulation setting circuit enables the voltage of the forward input end of the comparator to be higher than the voltage of the reverse input end in a charging mode, and the output end of the comparator outputs a high level signal;
and the level signal output by the comparator is converted into an analog dimming voltage through the integrator, so that the master control triode performs dimming control on the LED circuit according to the PWM signal.
6. The LED control method according to claim 5, wherein the voltage regulation setting circuit comprises a rectifier diode, a charging capacitor bank, a regulation triode, a charging resistor, a discharging resistor, a leveling resistor, a voltage regulation resistor and a ground resistor;
the emitter of the regulation triode is grounded, the base of the regulation triode is connected with the emitter of the output end of the coupler through the voltage regulating resistor, the collector of the regulation triode is connected with one end of the discharging resistor, and the other end of the discharging resistor is connected with the power supply through the charging resistor, is grounded through the charging capacitor bank and is connected with the positive input end of the comparator through the rectifier diode;
one end of the leveling resistor is connected with an emitting electrode at the output end of the coupler, and the other end of the leveling resistor is grounded;
one end of the grounding resistor is connected with the reverse input end of the comparator, and the other end of the grounding resistor is grounded.
7. The LED control method of claim 6, wherein the method of the voltage regulation setting circuit discharging the comparator with the voltage at the reverse input terminal higher than the voltage at the forward input terminal comprises: when the coupler is conducted, the regulating triode is conducted to drive the charging capacitor bank to discharge through the discharging resistor, so that the voltage of the reverse input end of the comparator is higher than that of the forward input end.
8. The LED control method of claim 6, wherein the step of charging the voltage regulation setting circuit to make the voltage at the forward input terminal of the comparator higher than the voltage at the reverse input terminal comprises: when the coupler is cut off, the regulating triode is cut off to drive the charging capacitor bank to be charged through the charging resistor, so that the voltage of the forward input end of the comparator is higher than the voltage of the reverse input end.
9. The LED control method of claim 5, wherein the main control transistor performs dimming control on the LED circuit at a maximum set power when the output terminal of the comparator outputs a high level signal.
10. The LED control method of claim 5, further comprising:
the dimming setting circuit carries out real-time voltage division processing on the power supply voltage;
and the power supply voltage is output to the base electrode of the master control triode after voltage division treatment, so that the base electrode of the master control triode has a preset saturated switching-on state.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130328505A1 (en) * 2012-06-08 2013-12-12 Laurence P. Sadwick Dimmer for Dimmable Drivers
CN109309989A (en) * 2018-10-15 2019-02-05 深圳市崧盛电子股份有限公司 A kind of All-in-One dim signal processing circuit
CN109413803A (en) * 2018-12-06 2019-03-01 矽力杰半导体技术(杭州)有限公司 LED adjusting control circuit
CN111212497A (en) * 2018-11-13 2020-05-29 卡任特照明解决方案有限公司 Driving circuit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130328505A1 (en) * 2012-06-08 2013-12-12 Laurence P. Sadwick Dimmer for Dimmable Drivers
CN109309989A (en) * 2018-10-15 2019-02-05 深圳市崧盛电子股份有限公司 A kind of All-in-One dim signal processing circuit
CN111212497A (en) * 2018-11-13 2020-05-29 卡任特照明解决方案有限公司 Driving circuit
CN109413803A (en) * 2018-12-06 2019-03-01 矽力杰半导体技术(杭州)有限公司 LED adjusting control circuit

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