CN117641655A

CN117641655A - Dimming control circuit and LED lighting device

Info

Publication number: CN117641655A
Application number: CN202210969230.3A
Authority: CN
Inventors: 陈小平
Original assignee: Meixinsheng Technology Beijing Co ltd
Current assignee: Meixinsheng Technology Beijing Co ltd
Priority date: 2022-08-12
Filing date: 2022-08-12
Publication date: 2024-03-01

Abstract

The application relates to a dimming control circuit and an LED lighting device; the dimming control circuit comprises a charging branch, an energy storage unit and a control unit; the first end of the energy storage unit is connected with a power supply, the second end of the energy storage unit is connected with the first end of the charging branch, and the second end of the charging branch is grounded to form a charging circuit; the energy storage unit is connected with the load in parallel to form a discharge circuit; the control unit generates a control signal according to the second voltage signal and the reference signal and outputs the control signal to the charging branch circuit, and the conduction time of the charging branch circuit is controlled to adjust the peak current and the average power on the energy storage unit. The dimming control circuit adjusts the signal gain according to the voltage peak signal of the power supply, can realize stable control of constant current and constant power no matter the voltage of the power supply, and can be used commonly under high voltage and low voltage conditions; the power of the LED load can be indirectly controlled by controlling the stored energy of the energy storage unit, so that the open-loop control of the output power is realized, and a COMP pin and an additional capacitor are not needed.

Description

Dimming control circuit and LED lighting device

Technical Field

The application relates to the technical field of LED intelligent dimming, in particular to a dimming control circuit and an LED lighting device.

Background

The LED light source is a light source based on a light emitting diode and has the advantages of low-voltage power supply, low energy consumption, strong applicability, high stability, short response time, no pollution to the environment, multicolor light emission and the like. With the continuous development of LED technology, LED light sources are widely used, and scenes such as markets, factories, houses, etc. use a large number of LED light sources as illumination or decoration, and adjust the brightness of the LED light sources when necessary. Along with the application of LED illumination global markets, special illumination such as stage lamps, projection backlight, intelligent home illumination and the like has higher and higher requirements on dimming precision and dimming depth.

With the application of the LED illumination global market, the national standard iterates continuously, the latest DLC V5.1 standard provides higher requirements for an LED driving scheme: (1) The input power change in the full voltage range is not more than plus or minus 10%; (2) At least one dimming mode is integrated, and in the actual process, the T tube can only select silicon controlled rectifier for dimming; (3) The silicon controlled rectifier dimming scheme cannot meet the requirement of full-voltage power variation.

In the related art, the dimming scheme on the market at present can only meet the control under one power supply voltage condition, that is, the low voltage (for example, 110/120 Vac) and the high voltage (for example, 220/230 Vac) inputs cannot be commonly used in one circuit, so that the requirement of the latest technical standard is not met.

Disclosure of Invention

To overcome at least to some extent the problem that dimming schemes in the related art cannot be commonly used under high-voltage and low-voltage input conditions, the present application provides a dimming control circuit and an LED lighting device.

According to a first aspect of embodiments of the present application, there is provided a dimming control circuit, including: the charging branch, the energy storage unit and the control unit;

the first end of the energy storage unit is connected with a power supply, the second end of the energy storage unit is connected with the first end of the charging branch, and the second end of the charging branch is grounded to form a charging circuit; when the charging branch is conducted, the power supply charges the energy storage unit through a charging circuit;

the energy storage unit is used for forming a discharge circuit in parallel with the load; when the charging branch is disconnected, the energy storage unit supplies power to a load through the discharging circuit;

the control unit is used for detecting the output voltage of the energy storage unit when the energy storage unit discharges; the control unit is also used for receiving a dimming signal; the control unit comprises a variable gain amplifier, a variable gain control unit and a control unit, wherein the variable gain amplifier is used for adjusting the gain of the control unit according to the output voltage and the dimming signal and outputting a voltage signal with a constant peak value as a reference signal;

the second detection end of the control unit is connected with the charging branch circuit to acquire a second voltage signal when the energy storage unit is charged; the control unit is used for generating a control signal according to the second voltage signal and the reference signal and outputting the control signal to the charging branch, and controlling the conduction time of the charging branch so as to adjust the peak current and the average power on the energy storage unit.

Further, the charging branch comprises a switch unit and a second voltage detection unit;

the input end of the switch unit is a first end of the charging branch and is used for being connected with a second end of the energy storage unit;

the output end of the switch unit is connected with the first end of the second voltage detection unit;

the second end of the second voltage detection unit is a second end of the charging branch and is used for grounding;

the control end of the switch unit is used for receiving a control signal output by the control unit; the switch unit is turned on or off under the action of a control signal.

Further, a second detection end CS of the control unit is connected to the first end of the second voltage detection unit, so as to obtain a second voltage signal when the energy storage unit is charged.

Further, the switching unit is a switching tube Q1; the control end of the switching tube Q1 is connected with the output end of the control unit;

the second voltage detection unit is a resistor RCS; the resistor RCS converts the current of the charging branch during operation into a second voltage signal and transmits the second voltage signal to the control unit.

Further, the control unit is configured to perform the following control actions:

when the second voltage signal rises to reach a threshold voltage, the charging branch is controlled to be disconnected; wherein the threshold voltage is generated from a reference signal.

Further, the control unit further includes: the device comprises a first voltage detection module, a third voltage detection module and a voltage comparison module;

the input end of the first voltage detection module is a first detection end HV of the control unit; the power supply signal enters the first voltage detection module from the first detection end HV, and a first voltage signal is generated and transmitted to the variable gain amplifier;

the input end of the third voltage detection module is a third detection end FB of the control unit; the discharge signal enters the third voltage detection module from the third detection end FB, and a third voltage signal is generated and transmitted to the variable gain amplifier;

the variable gain amplifier comprises a dimming input end DIM, and is used for acquiring a dimming signal; the variable gain amplifier converts the acquired first voltage signal, third voltage signal and dimming signal into threshold voltage and outputs the threshold voltage to a first input end of the voltage comparison module;

the second input end of the voltage comparison module is a second detection end CS of the control unit and is used for acquiring a second voltage signal; when the second voltage signal rises to reach the threshold voltage, the voltage comparison module outputs a low-level control signal to control the charging branch to be disconnected.

Further, the control unit further includes: a gain locking module; the input end of the gain locking module is connected with the first voltage detection module, and the output end of the gain locking module is connected with the variable gain amplifier;

the first voltage detection module is used for detecting the peak voltage of an input power supply and outputting a peak voltage signal to the gain locking module;

the gain locking module is used for detecting the silicon controlled rectifier dimming signal and locking the gain of the variable gain amplifier according to the peak voltage signal when the silicon controlled rectifier dimming signal is detected.

The control unit further includes: a linear compensation module; the input end of the linear compensation module is connected with the third voltage detection module, and the output end of the linear compensation module is connected with the second input end of the voltage comparison module;

the linear compensation module is used for compensating the second voltage signal connected to the voltage comparison module according to the third voltage signal.

In some embodiments, the energy storage unit is an inductance L1; the third detection end FB of the control unit is connected with the second end of the inductor L1, and a third voltage signal when the inductor L1 discharges is obtained.

In other embodiments, the energy storage unit is a transformer T1; the two ends of the primary winding of the transformer T1 are respectively a first end and a second end of the energy storage unit; the two ends of the secondary winding of the transformer T1 are used for connecting a load; the third detection end FB of the control unit is connected to the second end of the primary winding of the transformer T1, and obtains a third voltage signal when the primary winding of the transformer T1 discharges.

According to a second aspect of embodiments of the present application, there is provided an LED lighting device, comprising: the dimming control circuit as recited in any one of the above embodiments; the load comprises at least one LED lamp.

The technical scheme provided by the embodiment of the application has the following beneficial effects:

the dimming control circuit adjusts the signal gain according to the voltage peak signal of the power supply and outputs the voltage signal with a constant peak as a reference signal, so that stable control of constant current and constant power can be realized no matter the voltage of the power supply, and the dimming control circuit can be used under the conditions of high voltage and low voltage; according to the scheme, the conduction time of the charging branch is controlled, namely the charging current peak value of the energy storage unit is controlled, and the stored energy of the energy storage unit is equal to the released energy, so that the power of the LED load can be indirectly controlled by controlling the stored energy of the energy storage unit, the open loop control of the output power is realized, the COMP pin and the external capacitor connected to the LED load are not needed, and the complexity of a hardware circuit is reduced.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

Fig. 1 is a schematic structural diagram of a dimming control circuit according to an embodiment of the present disclosure.

FIG. 2 is a schematic diagram of a BUCK-BOOST circuit according to an embodiment of the present application.

Fig. 3 is a schematic diagram of a FLY-BACK circuit according to an embodiment of the present application.

Fig. 4 is a block diagram of the inside of a chip according to an embodiment of the present application.

Fig. 5 is an input ac voltage waveform shown in an embodiment of the present application.

Fig. 6 is a voltage waveform after bridge rectifier according to an embodiment of the present application.

Fig. 7 is a voltage waveform of different input voltages shown in an embodiment of the present application.

Fig. 8 is a waveform of a voltage signal output to CMP1 after passing through the GC module according to an embodiment of the present application.

Fig. 9 is an inductor current waveform when a buck-boost circuit MOS is turned on, and is also a transformer primary current waveform when a Fly-back circuit MOS is turned on, as shown in the embodiment of the present application.

Fig. 10 is an inductor current waveform when the Fly-boost diode D1 of the buck-boost circuit is turned on, and is also a transformer secondary current waveform when the Fly-back circuit MOS is turned on, as shown in the embodiment of the present application.

Fig. 11 is a waveform of a reference voltage of a front-cut thyristor dimming CMP1 according to an embodiment of the present application.

Fig. 12 is a current waveform of a front-cut thyristor dimming inductor (transformer primary) energy storage according to an embodiment of the present application.

Fig. 13 is a current waveform when a cut-forward thyristor dimming inductor (transformer secondary) is released, as shown in an embodiment of the present application.

Fig. 14 is a waveform of a reference voltage of a back-cut thyristor dimming CMP1 according to an embodiment of the present application.

Fig. 15 is a current waveform of a backward-cut thyristor dimming inductor (transformer primary) energy storage according to an embodiment of the present application.

Fig. 16 is a current waveform when a back-cut thyristor dimming inductor (transformer secondary) is released, as shown in an embodiment of the present application.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present application. Rather, they are merely examples of apparatus consistent with some aspects of the present application as detailed in the accompanying claims.

Fig. 1 is a schematic diagram illustrating a structure of a dimming control circuit according to an exemplary embodiment. The dimming control circuit includes: a charging branch 1, an energy storage unit 2 and a control unit 3;

the first end of the energy storage unit 2 is connected with a power supply, the second end of the energy storage unit is connected with the first end of the charging branch 1, and the second end of the charging branch 1 is grounded to form a charging circuit; when the charging branch 1 is conducted, a power supply charges the energy storage unit 2 through a charging circuit;

the energy storage unit 2 is used for forming a discharge line in parallel with a load; when the charging branch 1 is disconnected, the energy storage unit 2 supplies power to a load through the discharging circuit;

the control unit 3 is used for detecting the output voltage of the energy storage unit 2 when discharging; the control unit 3 is further configured to receive a dimming signal; the control unit 3 includes a variable gain amplifier for adjusting its own gain according to the output voltage and the dimming signal, and outputting a constant peak voltage signal as a reference signal;

the second detection end of the control unit 3 is connected with the charging branch 1 to acquire a second voltage signal when the energy storage unit 2 is charged; the control unit 3 is configured to generate a control signal according to the second voltage signal and the reference signal, output the control signal to the charging branch 1, and control the on time of the charging branch 1, so as to adjust the peak current and the average power on the energy storage unit 2.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1, in some embodiments of the present application, the charging branch 1 includes a switching unit 101 and a second voltage detection unit 102. The second detection terminal CS of the control unit 3 is connected to the first terminal of the second voltage detection unit 102, and obtains a second voltage signal when the energy storage unit 2 is charged.

The input end of the switch unit 101 is a first end of the charging branch 1 and is used for connecting a second end of the energy storage unit 2; an output end of the switch unit 101 is connected with a first end of the second voltage detection unit 102; the second terminal of the second voltage detecting unit 102 is a second terminal of the charging branch 1, and is used for grounding. The control end of the switch unit 101 is used for receiving the control signal output by the control unit 3; the switching unit 101 is turned on or off by a control signal.

In practical application, referring to fig. 2 and 3, the switching unit 101 is a switching tube Q1; the control end of the switching tube Q1 is connected with the output end of the control unit 3. The second voltage detection unit 102 is a resistor RCS; the resistor RCS converts the current of the charging branch 1 during operation into a second voltage signal, which is transmitted to the control unit 3.

In the solution of the present application, the energy storage unit 2 may be implemented by different devices, such as an inductor or a transformer, in different embodiments. The working principle of the dimming control circuit of the present application will be explained in detail below by taking these two cases as examples.

In a first embodiment, the operating principle of a BUCK-BOOST (BUCK-BOOST) circuit.

As shown in fig. 2, in some embodiments of the present application, the energy storage unit 2 is an inductance L1; the third detection end FB of the control unit 3 is connected to the second end of the inductor L1, and obtains a third voltage signal when the inductor L1 discharges.

Referring to fig. 2, the step-up/step-down circuit is operated by first outputting a high level from the GATE pin of the chip U1, turning on Q1, flowing current from the input L or N through Bridge to led+, inductor L1, switching transistor Q1, inductance peak current detection resistor RCS, and returning to the input N or L. When the voltage on the inductance peak current detection RCS rises to reach the threshold voltage set in the chip, the switching tube Q1 is turned off, and the inductance current flows through L1, D1 and C2 and the parallel circuits of the LEDs 1 to LEDn to form a discharge loop. And so on.

In the second embodiment, the flyback (FLY-BACK) circuit works in principle.

As shown in fig. 3, in some embodiments of the present application, the energy storage unit 2 is a transformer T1; the two ends of the primary winding of the transformer T1 are respectively a first end and a second end of the energy storage unit 2; the load is connected between the two ends of the secondary winding of the transformer T1. The third detection terminal FB of the control unit 3 is connected to the second terminal of the primary winding of the transformer T1, and obtains a third voltage signal when the primary winding of the transformer T1 discharges.

Referring to fig. 3, after power-up, the flyback circuit is operated by first outputting a high level from the GATE pin of the chip U1, turning on Q1, and flowing current from the input L or N into Bridge to led+, the primary of the T1 transformer, the switching tube Q1, the inductance peak current detection resistor RCS, and returning to the input N or L. When the voltage on the inductance peak current detection RCS rises to reach the threshold voltage set in the chip, the switching tube Q1 is cut off, and the secondary side of the T1 transformer, the D1 and the C2 and the LEDs 1-LEDn are connected in parallel to form a discharge loop. And so on.

The scheme of the application is expanded and explained below by combining with a specific application scene.

In the technical solution of the present application, the control unit 3 is configured to execute the following control actions: when the second voltage signal rises to reach the threshold voltage, the charging branch 1 is controlled to be disconnected; wherein the threshold voltage is generated from the reference signal.

It is readily understood that there are two different implementations of the control unit 3: the first scheme is that the control unit 3 adopts MCU (Microcontroller Unit, micro control unit) and other processing chips, and calculates the acquired signals through programs burnt in the chips to generate control signals; the second scheme is to build a hardware circuit, directly process the collected signals through the hardware circuit, and generate control signals, for example, the hardware circuit shown in fig. 4 can be adopted, so that the control action of the scheme can be realized.

Referring to fig. 4, the dimming control circuit of the present application, the control unit 3 includes: a variable gain amplifier (GC), a first voltage detection module (Vsine Peak Detect, voltage peak detection module, VPD for short), a third voltage detection module (OVP/FB, over Voltage Protection, overvoltage protection) and a voltage comparison module (CMP 1). In some embodiments, the first voltage detection module, the third voltage detection module, the variable gain amplifier, and the voltage comparison module are integrated in the same chip, as shown in fig. 4. In other embodiments, the first voltage detection module, the second voltage detection module, the variable gain amplifier, and the voltage comparison module may also be built by respective relatively independent circuits.

The input end of the first voltage detection module is a first detection end HV of the control unit 3; the power supply signal enters the first voltage detection module from the first detection end HV, and generates a first voltage signal and transmits the first voltage signal to the variable gain amplifier. The input end of the third voltage detection module is a third detection end FB of the control unit 3; the discharge signal enters the third voltage detection module from the third detection end FB, and a third voltage signal is generated and transmitted to the variable gain amplifier.

In order to more clearly clarify the advantages of the present solution over the prior art, a detailed description of the features of the present solution is provided below in connection with specific embodiments.

1. And the controllable silicon and the intelligent light modulation are combined. The dimming control circuit of the invention can adapt two dimming input modes, namely a silicon controlled rectifier dimming interface and a DIM dimming interface.

(1.1) the thyristor is used for dimming in a chopper mode (it is to be noted that the thyristor is connected to a live wire of an input power supply, not shown in the figure), that is, a part of the input voltage is cut off, which corresponds to total voltage reduction and power reduction, thereby playing a role in dimming. Fig. 11-13 show waveforms associated with cut-forward thyristor dimming (i.e., with a portion of the front end of the input voltage waveform cut-off), fig. 11 is a CMP1 reference voltage waveform, fig. 12 is a current waveform when the energy storage unit is charged, and fig. 13 is a current waveform when the energy storage unit is discharged. Fig. 14-16 show waveforms associated with the cut-back thyristor dimming (i.e., the end of the input voltage waveform is cut away), fig. 14 is a CMP1 reference voltage waveform, fig. 15 is a current waveform when the energy storage unit is charged, and fig. 16 is a current waveform when the energy storage unit is discharged.

When the silicon controlled rectifier is adopted for dimming, the peak voltage can not be identified due to chopping, so a Dimmer sense GC gain locked module (namely a dimming induction GC gain locking module, abbreviated as DSGL module) is arranged, and the gain can be directly locked through the module.

Referring to fig. 4, the control unit 3 further includes: gain lock module (DSGL module); the input end of the gain locking module is connected with the first voltage detection module (VPD module), and the output end of the gain locking module is connected with the variable gain amplifier (GC). The first voltage detection module is used for detecting the peak voltage of an input power supply and outputting a peak voltage signal to the gain locking module. The gain locking module is used for detecting the silicon controlled rectifier dimming signal and locking the gain of the variable gain amplifier according to the peak voltage signal when the silicon controlled rectifier dimming signal is detected.

Silicon controlled rectifier dimming principle: when the DSGL module detects that the thyristor dimmer is connected, a gain is locked according to the output result of the Vsine Peak Detect module, and the gain corresponding to 120Vac or 230Vac is not changed along with the values of the input voltage and the FB voltage. The locking function of the DSGL module is that the gain can be preset in advance, i.e. the locking effect is achieved, since there are only two voltages (120 and 230).

(1.2) DIM dimming adopts a direct input mode, for example, the maximum voltage allowed to be input is 5V, and 4V can be directly input in actual dimming, namely, dimming is performed by adjusting the voltage. 0-10V dimming principle of DIM dimming mode: referring to fig. 4, a dimming signal is introduced into the inside of the chip through DIM introduction, and the amplitude of the output sinusoidal voltage envelope of the GC module is adjusted to adjust the output current.

2. Constant power control technique, automatic gain control. Based on the voltage of HV and the signal of the dimming input terminal DIM, a threshold voltage can be determined; the principle is that when the voltage rises to this value, the charging is considered to reach the required power; transmitting the voltage signal to the CMP1, which can be used for comparing with the voltage of the CS to control the Q1 to be closed; thus, by controlling the on-time of Q1, the charging power is controlled, thereby realizing control of constant power. It should be noted that CMP1 is only used to control the switching tube Q1 to be turned off, and cannot control the switching tube Q1 to be turned on; referring to fig. 4, OSC is an oscillator module, and is preset, so that the oscillator OSC can turn on the switching transistor Q1 at regular time, thereby realizing the cycle control of Q1.

Referring to fig. 2, the variable gain amplifier includes a dimming input DIM for acquiring a dimming signal; the variable gain amplifier converts the acquired first voltage signal, third voltage signal and dimming signal into threshold voltage and outputs the threshold voltage to the first input end of the voltage comparison module. The second input end of the voltage comparison module is a second detection end CS of the control unit 3 and is used for acquiring a second voltage signal; when the second voltage signal rises to reach the threshold voltage, the voltage comparison module outputs a low-level control signal to disconnect the switch tube Q1, so as to control the disconnection of the charging branch 1.

The constant power principle of the scheme is further explained below in connection with voltage waveforms on the various devices in the dimming control circuit. The input ac voltage waveform is shown in fig. 5, the voltage waveform after bridge rectifier is shown in fig. 6, and the half-wave sine voltage waveform of different peaks is shown in fig. 7 when different input voltages are obtained. In the scheme of the present application, the input voltage passes through a GC (variable gain amplifier) inside the IC (i.e., a control unit), and the variable gain amplifier changes the gain of the GC according to the peak voltage detected by a Vsine Peak Detect module (VPD module for short), so as to obtain a sinusoidal voltage waveform with a constant peak value, and as shown in fig. 8, the sinusoidal voltage is used as a comparison voltage reference of the chip CMP1, so as to obtain an inductance (transformer primary) current waveform shown in fig. 9. Since buck-boost and Flyback operate in DCM (Discontinuous Conduction Mode ) mode, the energy stored in the inductor L1 (or the transformer T1) and the energy released are equal, so that the output power can be controlled by controlling the stored energy of the inductor L1 (or the transformer T1), and since the GC module can control the energy stored in the inductor (transformer) to be the same at different input voltages, the output power can be constant in the full voltage range.

3. The circuit topology output voltage detection mode comprises the following steps: differential detection techniques of input voltage (voltage measured on HV pin) and inductor voltage (voltage measured on FB pin). The difference between the two is equal to the output voltage for achieving open circuit protection (i.e. overvoltage protection). The scheme of the application adopts an output voltage detection technology, as shown in fig. 2 and 3, an FB pin in the drawing is used for collecting the voltage at one end when the inductor L1 discharges; the difference between the voltage and the peak value of the input alternating voltage (acquired through the HV pin) calculates the output voltage, and output overvoltage protection and output constant current control can be realized through the value.

(3.1) referring to fig. 2 and 3, according to the constant current principle of the present application, the output voltage is detected by detecting the voltage of the inductor L1 (or the transformer T1) when the FB pin discharges, and when the output voltage changes, the gain of the GC module is linearly adjusted to achieve a constant output current.

(3.2) when Q1 is turned off, the voltage of FB is positive, and the voltage at HV is negative, so the difference between the two is the output voltage; under normal conditions, the power of the inductor L1 is fixed, but along with the change of a load, the voltage can change, in order to realize steady-state, the FB interface can identify a voltage signal at the voltage signal, and the voltage signal is fed back to the VPD module again, a new threshold voltage is calculated again and is transmitted to the CMP1, and the comparison unit can control the inductance charge quantity of the next round through new comparison, so that the steady-state is continuously maintained. The OSC is an oscillator module, and is preset, so that Q1 can be turned on at fixed time to realize cycle control of Q1.

The constant current principle of the scheme is that if a load is empty, the output voltage is overlarge; at the moment, after the VPD detection and the CMP1 comparison, the Q1 is controlled to be disconnected, so that overvoltage protection is realized.

4. And the detection value of the charging current is compensated, so that the measurement accuracy is improved, and the control accuracy is further improved.

Referring to fig. 2, the control unit 3 further includes: a linearity compensation module (CSPeak Detect line compensation, i.e., CS interface peak detection linearity compensation module); the input end of the linear compensation module is connected with the third voltage detection module (OVP/FB), and the output end of the linear compensation module is connected with the second input end of the voltage comparison module (CMP 1). The linear compensation module is used for compensating the second voltage signal connected to the voltage comparison module according to the third voltage signal.

Referring to fig. 2, since the power supply voltage is finally grounded from the initial position through the resistor RCS during charging, a small time interval t is required (although a short time interval is still a certain effect), and since different voltages may cause different currents, that is, the slopes of the current changes may be inconsistent, the voltage detected by the CS interface may deviate, and thus the voltage input to the comparison unit may have an error, a CSPeak Detect line compensation module is provided, which may compensate the voltage conducted from the CS interface to the CMP1+, and correct the error value, so as to improve measurement accuracy and control accuracy.

In summary, the technical scheme of the application has the following advantages:

(1) The working voltage range of the prior art scheme is narrow, and only one of 120Vac or 230Vac can be applied; and simple linear compensation is adopted, and the linear compensation range is smaller. The scheme of the application adopts a unique gain control circuit to realize constant power in a full voltage range; after the dimmer is connected, whether the input voltage is 120Vac or 230Vac can be automatically identified according to the input voltage, and the gain of the gain controller is adjusted to be adaptive to the global power grid voltage working voltage range.

(2) In the prior art, the control of output voltage and current is usually realized by a closed loop, a COMP pin is needed, and an additional capacitor forms a closed loop. The scheme of the application directly and open-loop controls the output voltage and current, and a COMP pin and an external capacitor are not needed.

The embodiment of the application also provides an LED lighting device, which is characterized in that the dimming control circuit according to any one of the embodiments above; the load comprises at least one LED lamp. Referring to fig. 2 and 3, when the load includes a plurality of LED lamps, the plurality of LED lamps are connected in series therebetween. With respect to the LED lighting device in the present embodiment, the specific circuit configuration of the dimming control circuit has been described in detail in the previous embodiment, and will not be explained in detail here.

It is to be understood that the same or similar parts in the above embodiments may be referred to each other, and that in some embodiments, the same or similar parts in other embodiments may be referred to.

It should be noted that in the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present application, unless otherwise indicated, the meaning of "plurality" means at least two.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives, and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.

Claims

1. A dimming control circuit, comprising: a charging branch (1), an energy storage unit (2) and a control unit (3);

the first end of the energy storage unit (2) is connected with a power supply, the second end of the energy storage unit is connected with the first end of the charging branch circuit (1), and the second end of the charging branch circuit (1) is grounded to form a charging circuit; when the charging branch circuit (1) is conducted, a power supply charges the energy storage unit (2) through a charging circuit;

the energy storage unit (2) is used for forming a discharge line in parallel with a load; when the charging branch circuit (1) is disconnected, the energy storage unit (2) supplies power to a load through the discharging circuit;

the control unit (3) is used for detecting the output voltage of the energy storage unit (2) when the energy storage unit discharges; the control unit (3) is also used for receiving a dimming signal; the control unit (3) comprises a variable gain amplifier for adjusting the gain of the control unit according to the output voltage and the dimming signal and outputting a voltage signal with a constant peak value as a reference signal;

a second detection end of the control unit (3) is connected with the charging branch (1) to acquire a second voltage signal when the energy storage unit (2) is charged; the control unit (3) is used for generating a control signal according to the second voltage signal and the reference signal and outputting the control signal to the charging branch (1), and controlling the conduction time of the charging branch (1) so as to adjust the peak current and the average power on the energy storage unit (2).

2. Dimming control circuit according to claim 1, characterized in that the charging branch (1) comprises a switching unit (101) and a second voltage detection unit (102);

the input end of the switch unit (101) is a first end of the charging branch (1) and is used for being connected with a second end of the energy storage unit (2);

the output end of the switch unit (101) is connected with the first end of the second voltage detection unit (102);

the second end of the second voltage detection unit (102) is a second end of the charging branch (1) and is used for grounding;

the control end of the switch unit (101) is used for receiving a control signal output by the control unit (3); the switch unit (101) is turned on or off under the action of a control signal.

3. Dimming control circuit according to claim 2, characterized in that the second detection terminal CS of the control unit (3) is connected to the first terminal of the second voltage detection unit (102) for obtaining a second voltage signal when the energy storage unit (2) is charged.

4. A dimming control circuit according to claim 3, characterized in that the switching unit (101) is a switching tube Q1; the control end of the switching tube Q1 is connected with the output end of the control unit (3);

the second voltage detection unit (102) is a resistor RCS; the resistor RCS converts the current of the charging branch (1) during operation into a second voltage signal and transmits the second voltage signal to the control unit (3).

5. Dimming control circuit according to any of claims 1-4, characterized in that the control unit (3) is adapted to perform the following control actions:

when the second voltage signal rises to reach a threshold voltage, the charging branch (1) is controlled to be disconnected; wherein the threshold voltage is generated from a reference signal.

6. Dimming control circuit according to claim 5, characterized in that the control unit (3) further comprises: the device comprises a first voltage detection module, a third voltage detection module and a voltage comparison module;

the input end of the first voltage detection module is a first detection end HV of the control unit (3); the power supply signal enters the first voltage detection module from the first detection end HV, and a first voltage signal is generated and transmitted to the variable gain amplifier;

the input end of the third voltage detection module is a third detection end FB of the control unit (3); the discharge signal enters the third voltage detection module from the third detection end FB, and a third voltage signal is generated and transmitted to the variable gain amplifier;

the second input end of the voltage comparison module is a second detection end CS of the control unit (3) and is used for acquiring a second voltage signal; when the second voltage signal rises to reach the threshold voltage, the voltage comparison module outputs a low-level control signal to control the charging branch (1) to be disconnected.

7. Dimming control circuit according to claim 6, characterized in that the control unit (3) further comprises: a gain locking module; the input end of the gain locking module is connected with the first voltage detection module, and the output end of the gain locking module is connected with the variable gain amplifier;

8. Dimming control circuit according to claim 6, characterized in that the control unit (3) further comprises: a linear compensation module; the input end of the linear compensation module is connected with the third voltage detection module, and the output end of the linear compensation module is connected with the second input end of the voltage comparison module;

9. Dimming control circuit according to any of claims 1-4, characterized in that the energy storage unit (2) is an inductance L1; the third detection end FB of the control unit (3) is connected with the second end of the inductor L1, and a third voltage signal when the inductor L1 discharges is obtained; or,

the energy storage unit (2) is a transformer T1; the two ends of the primary winding of the transformer T1 are respectively a first end and a second end of the energy storage unit (2); the two ends of the secondary winding of the transformer T1 are used for connecting a load; the third detection end FB of the control unit (3) is connected with the second end of the primary winding of the transformer T1, and a third voltage signal when the primary winding of the transformer T1 discharges is obtained.

10. An LED lighting device comprising a dimming control circuit as claimed in any one of claims 1-9; the load comprises at least one LED lamp.