CN219107721U

CN219107721U - Dimming control circuit

Info

Publication number: CN219107721U
Application number: CN202223601119.3U
Authority: CN
Inventors: 王彬
Original assignee: Meixinsheng Technology Beijing Co ltd
Current assignee: Meixinsheng Technology Beijing Co ltd
Priority date: 2022-12-30
Filing date: 2022-12-30
Publication date: 2023-05-30
Anticipated expiration: 2032-12-30

Abstract

The application provides a dimming control circuit, which quantizes a dimming signal through a dimming signal quantizing module, generates a control signal which linearly changes along with the dimming signal, performs peak control on an inductance current by using a peak control module, and outputs a signal indicating the turn-off starting time of a MOS tube to an R end of an RS trigger; the demagnetization detection module is used for carrying out demagnetization detection on the inductor and outputting a ZCD signal to the turn-off time control module, and the turn-off time control module is used for outputting a signal indicating the closing start time of the MOS tube to the S end of the RS trigger according to the ZCD signal and the control signal. The circuit realizes the switching control of the CRM mode and the DCM mode by controlling the peak value of the inductive current and the turn-off time of the MOS tube, thereby being capable of dimming in different modes according to the sensitivity of human eyes to brightness change and meeting the requirement of human eyes on comfortable dimming.

Description

Dimming control circuit

Technical Field

The application relates to the technical field of LED control, in particular to a dimming control circuit.

Background

The current dimming technology simply realizes the linear control of the brightness of the LED or has a simple brightness gradual change effect, but does not accord with the nonlinear feeling of human eye vision on brightness change, and poor user experience is caused. Medical research has shown that the perception of changes in luminance by the human eye is non-linear. Generally, a small change in brightness at a low brightness gives a great feeling to people; when the brightness is high, the larger brightness variation gives a smaller feeling. Therefore, the linear control of the brightness of the existing dimming technology is difficult to meet the requirement of human eye vision on comfortable dimming.

Disclosure of Invention

An objective of the embodiments of the present application is to provide a dimming control circuit, which is used for solving the problem that the linear control of the brightness of the existing dimming technology is difficult to meet the requirement of human eye vision on comfortable dimming.

The dimming control circuit comprises a dimming signal quantization module, a turn-off time control module, a demagnetization detection module, a peak value control module, an RS trigger and a driving module;

the input end of the dimming signal quantization module is used for inputting a dimming signal, and the two output ends of the dimming signal quantization module are respectively connected to the first input end of the turn-off time control module and the first input end of the peak value control module; the second input end of the turn-off time control module is connected with the output end of the demagnetization detection module; the output end of the turn-off time control module is connected with the S end of the RS trigger; the second input end of the peak value control module is connected to the source electrode of the MOS tube, and the output end of the peak value control module is connected with the R end of the RS trigger; the output end of the RS trigger is connected with the input end of the driving module, and the output end of the driving module outputs a driving signal to the grid electrode of the MOS tube.

In the technical scheme, the dimming signal is quantized through the dimming signal quantization module, a control signal which linearly changes along with the dimming signal is generated, peak control is carried out ON the inductance current through the peak control module, and an ON_END signal which indicates the turn-off starting time of the MOS tube is output to the R END of the RS trigger; the demagnetization detection module is used for carrying out demagnetization detection on the inductor and outputting a ZCD signal to the turn-OFF time control module, and the turn-OFF time control module is used for outputting an OFF_END signal indicating the closing start time of the MOS tube to the S END of the RS trigger according to the ZCD signal and the control signal. The circuit realizes the switching control of the CRM mode and the DCM mode by controlling the peak value of the inductive current and the turn-off time of the MOS tube, thereby being capable of dimming in different modes according to the sensitivity of human eyes to brightness change and meeting the requirement of human eyes on comfortable dimming. Wherein, CRM mode: the MOS tube is turned off, the inductance current is reduced, the demagnetizing detection module detects that the inductance current is reduced to zero, the MOS tube is immediately controlled to be closed, and the inductance current is increased. DCM mode: the MOS tube is turned off, the inductance current is reduced, the detected inductance current is reduced to zero, the MOS tube is not immediately controlled to be closed, the turn-off time (TOFF_FREE) of the MOS tube is increased through the turn-off time control module, and the TOFF_FREE time is ended, so that the MOS tube is controlled to be closed.

In some alternative embodiments, the peak control module is configured to peak control the inductor current, and output an on_end signal indicating a turn-off start time of the MOS transistor to an R terminal of the RS flip-flop.

In some alternative embodiments, the dimming signal quantization module is configured to quantize the dimming signal to generate the control signal that varies linearly with the dimming signal.

In some optional embodiments, the demagnetization detection module is configured to perform demagnetization detection on the inductor, and output a ZCD signal to the turn-off time control module;

and the turn-OFF time control module is used for outputting an OFF_END signal indicating the closing start time of the MOS tube to the S END of the RS trigger according to the ZCD signal and the control signal.

In some alternative embodiments, the D pole of the MOS transistor is connected to the negative terminal of the LED load through an inductor, and the S pole of the MOS transistor is grounded through a resistor Rs.

The control method of the dimming control circuit provided by the embodiment of the application comprises the following steps:

quantizing the dimming signal to generate a control signal which linearly changes along with the dimming signal;

detecting the inductance current, carrying out peak control on the inductance current, and controlling the turn-off starting time of the MOS tube;

detecting the demagnetizing state of the inductor, and controlling the closing start time of the MOS tube according to the demagnetizing state and the control signal.

In the technical scheme, through controlling the peak value of the inductance current and the turn-off time of the MOS tube, the switching control of the CRM mode and the DCM mode is realized, so that dimming of different modes can be carried out according to the sensitivity of human eyes to brightness change, and the requirement of human eyes on comfortable dimming is met. Wherein, CRM mode: the MOS tube is turned off, the inductance current is reduced, demagnetization detection is carried out, the detected inductance current is reduced to zero, the MOS tube is immediately controlled to be closed, and the inductance current is increased. DCM mode: the MOS tube is turned off, the inductance current is reduced, the MOS tube is not immediately controlled to be closed when the inductance current is detected to be reduced to zero, and the turn-off time (TOFF_FREE) of the MOS tube is increased until the TOFF_FREE time is ended, and the MOS tube is controlled to be closed.

In some alternative embodiments, the method further comprises:

the output current I0 is enabled to meet the following conditions by controlling the turn-off and turn-on of the MOS tube:

where k is a mode switching coefficient, D is a dimming signal duty cycle, and Ipk is a peak current.

In some alternative embodiments, the dimming control circuit includes a dimming signal quantization module, a turn-off time control module, a demagnetization detection module, a peak control module, an RS trigger, and a drive module;

In the technical scheme, the dimming signal is quantized through the dimming signal quantization module, a control signal which linearly changes along with the dimming signal is generated, peak control is carried out ON the inductance current through the peak control module, and an ON_END signal which indicates the turn-off starting time of the MOS tube is output to the R END of the RS trigger; the demagnetization detection module is used for carrying out demagnetization detection on the inductor and outputting a ZCD signal to the turn-OFF time control module, and the turn-OFF time control module is used for outputting an OFF_END signal indicating the closing start time of the MOS tube to the S END of the RS trigger according to the ZCD signal and the control signal. The circuit realizes the switching control of the CRM mode and the DCM mode by controlling the peak value of the inductive current and the turn-off time of the MOS tube, thereby being capable of dimming in different modes according to the sensitivity of human eyes to brightness change and meeting the requirement of human eyes on comfortable dimming.

In some alternative embodiments, quantizing the dimming signal to produce a control signal that varies linearly with the dimming signal includes:

and the dimming signal quantization module quantizes the dimming signal to generate a control signal which linearly changes along with the dimming signal, and sends the control signal to the peak value control module and the turn-off time control module.

In some optional embodiments, detecting the inductor current, and performing peak control on the inductor current, and controlling the turn-off start time of the MOS transistor, including:

and when receiving the control signal, the peak control module carries out peak control ON the inductance current and outputs an ON_END signal indicating the turn-off start time of the MOS tube to the R END of the RS trigger.

In some optional embodiments, detecting a demagnetizing state of the inductor, and controlling a closing start time of the MOS transistor according to the demagnetizing state and the control signal includes:

the demagnetizing detection module is used for carrying out demagnetizing detection on the inductor and outputting a ZCD signal to the turn-off time control module;

and outputting an OFF_END signal indicating the closing start time of the MOS tube to the S END of the RS trigger by the turn-OFF time control module according to the ZCD signal and the control signal.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a functional block diagram of a dimming control circuit according to an embodiment of the present disclosure;

fig. 2 is a flowchart of a control method of a dimming control circuit according to an embodiment of the present application;

fig. 3 is a circuit block diagram of a dimming control circuit according to an embodiment of the present disclosure;

fig. 4 is a signal waveform diagram provided in an embodiment of the present application.

Icon: the device comprises a 1-dimming signal quantization module, a 2-turn-off time control module, a 3-demagnetization detection module, a 4-peak value control module, a 5-RS trigger and a 6-driving module.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

The human eye vision senses light, is insensitive to the highlight, and is easily perceived by slight changes in the highlight. In the LED lighting intelligent dimming application, there is also a need to adapt to the light sensing of human eyes, and when the brightness is low, the dimming brightness variation amplitude is reduced, that is, when the LED lighting intelligent dimming application is configured to adjust one gear, the actual brightness variation amplitude is lower than the brightness variation when the LED lighting intelligent dimming application is high, and although the brightness variation amplitude is reduced when the LED lighting intelligent dimming application is low, the dimming use feeling is still good on the naked eyes based on the characteristic that the human eyes are more sensitive to the low brightness variation. In order to achieve such dimming effect, the embodiment of the application provides a dimming control circuit.

Referring to fig. 1, fig. 1 is a functional block diagram of a dimming control circuit according to an embodiment of the present application, which includes a dimming signal quantization module 1, an off-time control module 2, a demagnetization detection module 3, a peak control module 4, an RS trigger 5, and a driving module 6.

The input end of the dimming signal quantization module 1 is used for inputting a dimming signal, and two output ends of the dimming signal quantization module 1 are respectively connected to the first input end of the turn-off time control module 2 and the first input end of the peak value control module 4; the second input end of the turn-off time control module 2 is connected with the output end of the demagnetization detection module 3; the output end of the turn-off time control module 2 is connected with the S end of the RS trigger 5; the second input end of the peak value control module 4 is connected to the source electrode of the MOS tube, and the output end of the peak value control module 4 is connected to the R end of the RS trigger 5; the output end of the RS trigger 5 is connected with the input end of the driving module 6, and the output end of the driving module 6 outputs a driving signal to the grid electrode of the MOS tube.

In the embodiment of the application, a dimming signal is quantized by a dimming signal quantization module 1 to generate a control signal which linearly changes along with the dimming signal, a peak control module 4 is utilized to perform peak control ON the inductance current, and an ON_END signal indicating the turn-off start time of the MOS tube is output to the R END of an RS trigger 5; the demagnetizing detection module 3 is used for carrying out demagnetizing detection on the inductor and outputting a ZCD signal to the turn-OFF time control module 2, and the turn-OFF time control module 2 is used for outputting an OFF_END signal indicating the closing start time of the MOS tube to the S END of the RS trigger 5 according to the ZCD signal and the control signal. The circuit realizes the switching control of the CRM mode and the DCM mode by controlling the peak value of the inductive current and the turn-off time of the MOS tube, thereby being capable of dimming in different modes according to the sensitivity of human eyes to brightness change and meeting the requirement of human eyes on comfortable dimming. Wherein, CRM mode: the MOS tube is turned off, the inductance current is reduced, the demagnetizing detection module 3 detects that the inductance current is reduced to zero, the MOS tube is immediately controlled to be closed, and the inductance current is increased. DCM mode: the MOS tube is turned off, the inductance current is reduced, the detected inductance current is reduced to zero, the MOS tube is not immediately controlled to be closed, the turn-off time (TOFF_FREE) of the MOS tube is increased through the turn-off time control module 2, and the TOFF_FREE time is ended, so that the MOS tube is controlled to be closed.

The peak control module 4 is configured to perform peak control ON the inductor current, and output an on_end signal indicating the turn-off start time of the MOS transistor to the R END of the RS flip-flop 5. The dimming signal quantization module 1 is used for quantizing a dimming signal and generating a control signal which linearly changes along with the dimming signal. The demagnetization detection module 3 is used for carrying out demagnetization detection on the inductor and outputting a ZCD signal to the turn-off time control module 2; the turn-OFF time control module 2 is configured to output an off_end signal indicating a closing start time of the MOS transistor to an S terminal of the RS trigger 5 according to the ZCD signal and the control signal.

The D pole of the MOS tube is connected to the negative end of the LED load through the inductor, and the S pole of the MOS tube is grounded through the resistor Rs.

Referring to fig. 2, fig. 2 is a flowchart of a control method of a dimming control circuit according to an embodiment of the present application, which specifically includes:

step 100, quantifying the dimming signal to generate a control signal that varies linearly with the dimming signal;

step 200, detecting the inductive current, carrying out peak control on the inductive current, and controlling the turn-off starting time of the MOS tube;

and 300, detecting the demagnetizing state of the inductor, and controlling the closing start time of the MOS tube according to the demagnetizing state and the control signal.

In the embodiment of the application, through controlling the peak value of the inductance current and the turn-off time of the MOS tube, the switching control of the CRM mode and the DCM mode is realized, so that the dimming of different modes can be carried out according to the sensitivity of human eyes to brightness change, and the requirement of human eyes on comfortable dimming is met. Wherein, CRM mode: the MOS tube is turned off, the inductance current is reduced, demagnetization detection is carried out, the detected inductance current is reduced to zero, the MOS tube is immediately controlled to be closed, and the inductance current is increased. DCM mode: the MOS tube is turned off, the inductance current is reduced, the MOS tube is not immediately controlled to be closed when the inductance current is detected to be reduced to zero, and the turn-off time (TOFF_FREE) of the MOS tube is increased until the TOFF_FREE time is ended, and the MOS tube is controlled to be closed.

The dimming control circuit comprises a dimming signal quantization module 1, a turn-off time control module 2, a demagnetization detection module 3, a peak value control module 4, an RS trigger 5 and a driving module 6;

the input end of the dimming signal quantization module 1 is used for inputting a dimming signal, and the two output ends of the dimming signal quantization module 1 are respectively connected to the first input end of the turn-off time control module 2 and the first input end of the peak value control module 4; the second input end of the turn-off time control module 2 is connected with the output end of the demagnetization detection module 3; the output end of the turn-off time control module 2 is connected with the S end of the RS trigger 5; the second input end of the peak value control module 4 is connected to the source electrode of the MOS tube, and the output end of the peak value control module 4 is connected to the R end of the RS trigger 5; the output end of the RS trigger 5 is connected with the input end of the driving module 6, and the output end of the driving module 6 outputs a driving signal to the grid electrode of the MOS tube.

In the embodiment of the application, a dimming signal is quantized by a dimming signal quantization module 1 to generate a control signal which linearly changes along with the dimming signal, a peak control module 4 is utilized to perform peak control ON the inductance current, and an ON_END signal indicating the turn-off start time of the MOS tube is output to the R END of an RS trigger 5; the demagnetizing detection module 3 is used for carrying out demagnetizing detection on the inductor and outputting a ZCD signal to the turn-OFF time control module 2, and the turn-OFF time control module 2 is used for outputting an OFF_END signal indicating the closing start time of the MOS tube to the S END of the RS trigger 5 according to the ZCD signal and the control signal. The circuit realizes the switching control of the CRM mode and the DCM mode by controlling the peak value of the inductive current and the turn-off time of the MOS tube, thereby being capable of dimming in different modes according to the sensitivity of human eyes to brightness change and meeting the requirement of human eyes on comfortable dimming.

In some alternative embodiments, step 100, quantizing the dimming signal to generate a control signal that varies linearly with the dimming signal, includes: the dimming signal quantization module 1 quantizes the dimming signal, generates a control signal which linearly changes with the dimming signal, and sends the control signal to the peak value control module 4 and the off-time control module 2.

In some optional embodiments, step 200, detecting the inductor current, and performing peak control on the inductor current, and controlling the turn-off start time of the MOS transistor, includes: when receiving the control signal, the peak control module 4 performs peak control ON the inductor current and outputs an on_end signal indicating the turn-off start time of the MOS transistor to the R END of the RS flip-flop 5.

In some optional embodiments, step 300, detecting a demagnetizing state of the inductor, and controlling a closing start time of the MOS transistor according to the demagnetizing state and the control signal includes: the demagnetizing detection module 3 performs demagnetizing detection on the inductor and outputs a ZCD signal to the turn-off time control module 2; and the OFF-time control module 2 outputs an off_end signal indicating the closing start time of the MOS tube to the S END of the RS trigger 5 according to the ZCD signal and the control signal.

Specifically, referring to fig. 3, fig. 3 is a circuit block diagram of a dimming control circuit according to an embodiment of the present application. The dimming signal quantization module 1 receives the dimming signal for quantization and controls the turn-OFF time control module 2 and the peak value control module 4, the demagnetization detection module 3 outputs a ZCD signal to the turn-OFF time control module 2, and the turn-OFF time control module 2 outputs an OFF_END signal to the S pole of the RS trigger 5. The peak control module 4 also detects the inductance current of the inductance L1 and carries out peak control, the peak control module 4 outputs an ON_END signal to the R pole of the RS trigger 5, the output END of the RS trigger 5 is connected with the driving module 6, the output DRV driving signal of the driving module 6 is connected to the grid electrode of the MOS tube, the S pole of the MOS tube is grounded after passing through the resistor Rs, the D pole of the MOS tube is connected to the negative pole of the LED load through the inductance L1, the D pole of the MOS tube is also connected to the positive END of the LED load through the diode D1, and the positive END and the negative END of the LED load are also connected with the capacitor C0 in parallel. The DRV signal output by the driving module 6, the inductance current Il1 of the inductance L1, the off_end signal output by the OFF-time control module 2, the ZCD signal output by the demagnetization detecting module 3, and the on_end signal output by the peak control module 4 are shown in fig. 4.

The off-time control module 2 in this embodiment includes an integrating capacitor C1, an integrating capacitor C2, and a comparator. In one PWM switching period, the voltage of the negative input end of the comparator is equal to IR×T1/C2, IR is the reference current, if the voltage of the positive input end of the comparator is smaller than IR×T1/C2 in the time T1, demagnetization is finished, the output of the comparator cannot be overturned, the turn-off time of the MOS tube in the switching period still continues until IDIM×T2/C1 is larger than IR×T1/C2, IDIM is a current proportional to the duty ratio, and the next switching period is started, so that the current on the inductor is in an intermittent mode, namely a DCM mode. In contrast, before demagnetization is finished, the voltage of the positive input end of the comparator is always greater than or equal to the voltage of the negative input end, namely the input of the comparator is always logic high, the inductor current is reduced to zero, namely the demagnetization is finished, the next switching cycle is immediately controlled to enter, and the current on the inductor is in critical continuity, namely a CRM mode.

That is, when kxD is greater than or equal to 1, the output current I0 changes linearly with the duty ratio D, and is in CRM mode at this time, in the CRM mode, the MOS tube is turned off, the inductance current is reduced, the detected inductance current is reduced to zero, the MOS tube is immediately controlled to be closed, and the inductance current is increased.

When k×d <1, the output current I0 changes with the quadratic function of the duty ratio D, and the approximate index changes, and is in DCM mode at this time, in DCM mode, the MOS transistor is turned off, the inductor current decreases, the inductor current is detected to decrease to zero, the MOS transistor is not immediately controlled to be closed, but the MOS transistor turn-off time (toff_free) is increased, and the toff_free time is ended, and the MOS transistor is controlled to be closed.

Therefore, according to the mode switching coefficient k, the duty ratio corresponding to the brightness control line is determined, when the brightness is lower than the brightness control line, namely, when the brightness is low, the output current I0 linearly changes along with the duty ratio D, the dimming brightness change range is lower, and the dimming brightness change range is consistent with the characteristic that the human eyes easily feel slight brightness change when the brightness is low. When the brightness is higher than the brightness control line, namely, when the brightness is high, the output current I0 changes along with the quadratic function of the duty ratio D, the approximate index changes, and when the brightness is high, the dimming brightness change amplitude is higher, and the dimming brightness is consistent with the characteristic that human eyes are insensitive to the brightness change when the brightness is high. In the embodiment, when the brightness is low, the change amplitude of the actual brightness is lower than the brightness change when the brightness is high when one gear is regulated, and the brightness change amplitude is reduced when the brightness is low, but the dimming sense of use is improved on naked eyes based on the characteristic that people are more sensitive to the low brightness change, so that the user experience is improved.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.

Further, the units described as separate units may or may not be physically separate, and units displayed as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

Furthermore, functional modules in various embodiments of the present application may be integrated together to form a single portion, or each module may exist alone, or two or more modules may be integrated to form a single portion.

In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. The dimming control circuit is characterized by comprising a dimming signal quantization module, a turn-off time control module, a demagnetization detection module, a peak value control module, an RS trigger and a driving module;

the input end of the dimming signal quantization module is used for inputting a dimming signal, and the two output ends of the dimming signal quantization module are respectively connected to the first input end of the turn-off time control module and the first input end of the peak value control module; the second input end of the turn-off time control module is connected with the output end of the demagnetization detection module; the output end of the turn-off time control module is connected with the S end of the RS trigger; the second input end of the peak value control module is connected to the source electrode of the MOS tube, and the output end of the peak value control module is connected to the R end of the RS trigger; the output end of the RS trigger is connected with the input end of the driving module, and the output end of the driving module outputs a driving signal to the grid electrode of the MOS tube.

2. The circuit of claim 1, wherein the peak control module is configured to peak control the inductor current and output an on_end signal to the R terminal of the RS flip-flop indicating a turn-off start time of the MOS transistor.

3. The circuit of claim 1, wherein the dimming signal quantization module is configured to quantize the dimming signal to generate the control signal that varies linearly with the dimming signal.

4. The circuit as recited in claim 3 wherein said demagnetization detection module is configured to perform demagnetization detection on an inductor and output a ZCD signal to said off-time control module;

the OFF time control module is used for outputting an off_end signal indicating the closing start time of the MOS tube to the S END of the RS trigger according to the ZCD signal and the control signal.

5. The circuit of claim 1, wherein the D pole of the MOS transistor is connected to the negative terminal of the LED load through an inductor, and the S pole of the MOS transistor is grounded through a resistor Rs.