Depth dimming circuit of light-emitting element

Abstract

The invention provides a depth dimming circuit of a light-emitting element. The depth dimming circuit comprises a dimming voltage signal end, a main control switch, a first dimming circuit, a second dimming circuit and a switch control circuit. The first dimming circuit is used for outputting a first control signal based on a dimming voltage signal. The second dimming circuit comprises a comparison circuit which is used for comparing the dimming voltage signal with a voltage signal threshold value and outputting a second control signal. And the switch control circuit is used for outputting a master control signal according to the first control signal and the second control signal and controlling the master control switch so as to carry out deep dimming on the light-emitting element. When the dimming voltage signal is not smaller than the voltage signal threshold value, the total control signal changes along with the change of the first control signal, and when the dimming voltage signal is smaller than the voltage signal threshold value, the total control signal at least changes along with the change of the second control signal. A mixed dimming mode is adopted, the problem that the dimming depth of the light-emitting element is not enough is solved, and the circuit is simple in structure, low in cost, stable and reliable.

Description

Technical Field

[0001] This application relates to the field of depth dimming technology, and more particularly to a depth dimming circuit for a light-emitting element. Background Technology

[0002] A light-emitting diode (LED) is a device that converts electrical energy into light energy. LEDs are characterized by energy saving, environmental friendliness, fast response speed, and long lifespan. To meet the application requirements of different occasions, dimming control of the light-emitting diode is necessary. However, existing deep dimming circuits suffer from drawbacks such as insufficient dimming depth, complex circuit structure, and high cost. Summary of the Invention

[0003] This application provides a depth dimming circuit for a light-emitting element that has a simple circuit structure and low cost.

[0004] This application provides a depth dimming circuit for a light-emitting element, including:

[0005] The dimming voltage signal terminal is used to receive externally input dimming voltage signals;

[0006] The main control switch is electrically connected to the light-emitting element;

[0007] A first dimming circuit is electrically connected to the dimming voltage signal terminal and the light-emitting element; the first dimming circuit is used to output a first control signal based on the dimming voltage signal.

[0008] The second dimming circuit includes a comparator circuit electrically connected to the dimming voltage signal terminal, used to compare the dimming voltage signal with a voltage signal threshold, and output a second control signal; and

[0009] A switch control circuit, electrically connected to the first dimming circuit, the second dimming circuit, and the main control switch, is used to output a total control signal according to the first control signal and the second control signal to control the main control switch to perform deep dimming on the light-emitting element; wherein, when the dimming voltage signal is not less than the voltage signal threshold, the total control signal changes with the change of the first control signal, and when the dimming voltage signal is less than the voltage signal threshold, the total control signal changes at least with the change of the second control signal.

[0010] Preferably, the first control signal is a PWM signal; when the dimming voltage signal is less than the voltage signal threshold, the second control signal is a square wave signal, and the duty cycle of the square wave signal is different for different dimming voltage signals; the switch control circuit is used to combine the PWM signal and the square wave signal to output the total control signal; wherein, when the dimming voltage signal is not less than the voltage signal threshold, the total control signal with the same duty cycle as the PWM signal is output; when the dimming voltage signal is less than the voltage signal threshold, the total control signal is output by combining the PWM signal and the square wave signal; wherein when the dimming voltage signal is not less than the voltage signal threshold, the square wave signal is high or low, and the period of the square wave signal is greater than the period of the PWM signal.

[0011] Preferably, the first control signal is a PWM signal; when the dimming voltage signal is less than the voltage signal threshold, the second control signal is a square wave signal, and the duty cycle of the square wave signal is different for different dimming voltage signals; the switch control circuit is used to output the total control signal with the same duty cycle as the PWM signal when the dimming voltage signal is not less than the voltage signal threshold, and to output the total control signal with the same duty cycle as the square wave signal when the dimming voltage signal is less than the voltage signal threshold.

[0012] Preferably, the second dimming circuit further includes a sawtooth wave generation circuit, which generates a sawtooth wave voltage signal, wherein the voltage signal threshold is the maximum value of the sawtooth wave voltage signal.

[0013] Preferably, the sawtooth wave generating circuit includes:

[0014] A sawtooth wave voltage signal terminal is electrically connected to the comparator and is used to output the sawtooth wave voltage signal.

[0015] An adjustment switch is electrically connected between the sawtooth wave voltage signal terminal and the ground terminal;

[0016] A hysteresis comparator circuit is electrically connected between the sawtooth wave voltage signal terminal and the adjustment switch. The hysteresis comparator circuit includes an upper threshold and a lower threshold. The hysteresis comparator circuit is used to compare the sawtooth wave voltage signal with the upper threshold and the lower threshold respectively, and output an adjustment signal to control the adjustment switch.

[0017] Preferably, the depth dimming circuit includes a power supply terminal; the sawtooth wave generation circuit includes an adjustment branch, the adjustment branch includes a resistor and a capacitor, the resistor and the capacitor are connected in series between the power supply terminal and the ground terminal; the sawtooth wave voltage signal terminal is electrically connected between the resistor and the capacitor.

[0018] Preferably, the hysteresis comparison circuit includes a hysteresis comparator.

[0019] Preferably, the regulating switch includes an N-type MOS transistor.

[0020] Preferably, the first dimming circuit includes a sampling circuit, a signal control circuit, and an analog dimming circuit. The sampling circuit is electrically connected to the light-emitting element and is used to collect the current flowing through the light-emitting element and generate a sampling voltage signal. The analog dimming circuit is electrically connected to the dimming voltage signal terminal. The signal control circuit is used to output the first control signal according to the sampling voltage signal and the dimming voltage signal.

[0021] Preferably, the sampling circuit includes a sampling resistor connected in series with the light-emitting element.

[0022] Preferably, the depth dimming circuit includes an inductor connected in series with the light-emitting element.

[0023] Preferably, the depth dimming circuit includes a freewheeling diode connected in series with the light-emitting element.

[0024] Preferably, the switch control circuit includes an AND logic circuit, which includes a first access terminal, a second access terminal, and an operation output terminal. The first access terminal is electrically connected to the first dimming circuit, the second access terminal is electrically connected to the second dimming circuit, and the operation output terminal is electrically connected to the main control switch. The AND logic circuit is used to perform a logical AND operation on the first control signal and the second control signal.

[0025] Preferably, the depth of the light-emitting element corresponding to the voltage signal threshold is at most 10%.

[0026] The light-emitting element depth dimming circuit provided in this application embodiment includes a dimming voltage signal terminal, a main control switch, a first dimming circuit, a second dimming circuit, and a switch control circuit. The dimming voltage signal terminal is used to receive an externally input dimming voltage signal. The main control switch is electrically connected to the light-emitting element. The first dimming circuit is electrically connected to the dimming voltage signal terminal. The first dimming circuit is used to output a first control signal based on the dimming voltage signal. The second dimming circuit is electrically connected to the dimming voltage signal terminal. The second dimming circuit includes a comparison circuit, which is electrically connected to the dimming voltage signal terminal, and is used to compare the dimming voltage signal with a voltage signal threshold, and output a second control signal. The switch control circuit is electrically connected to the first dimming circuit, the second dimming circuit, and the main control switch. With this configuration, the depth dimming circuit, through the switch control circuit, outputs a total control signal based on the first and second control signals to control the main control switch, thereby performing depth dimming on the light-emitting element. Specifically, when the dimming voltage signal is not less than the voltage signal threshold, the total control signal changes with the change of the first control signal; when the dimming voltage signal is less than the voltage signal threshold, the total control signal changes with at least the change of the second control signal. This embodiment's depth dimming circuit employs a hybrid dimming method, combining the first and second control signals for depth dimming to address the problem of insufficient dimming depth of the light-emitting element. This results in a simple circuit structure, low cost, and stable and reliable operation.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0028] Figure 1 The diagram shown is a schematic block diagram of one embodiment of the depth dimming circuit of this application.

[0029] Figure 2 As shown Figure 1 The schematic block diagram shows another embodiment of the depth dimming circuit.

[0030] Figure 3 As shown Figure 2 The diagram shows a signal waveform of the depth dimming circuit.

[0031] Figure 4 As shown Figure 2 Another signal waveform diagram of the depth dimming circuit shown.

[0032] Figure 5 As shown Figure 2 The circuit diagram of the second adjustment circuit of the depth dimming circuit is shown.

[0033] Figure 6 As shown Figure 2 The circuit diagram shows another embodiment of the depth dimming circuit.

[0034] Figure 7 As shown Figure 2 The circuit diagram shows another embodiment of the depth dimming circuit. Detailed Implementation

[0035] The depth dimming circuit of the light-emitting element provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the various embodiments and implementations described below can be combined arbitrarily with each other.

[0036] The light-emitting element can be an LED, which converts electrical energy into light energy and features energy saving, environmental friendliness, fast response speed, and long lifespan. A depth dimming circuit is used to deeply dim the LED, adjusting its brightness or depth.

[0037] Figure 1 The diagram shown is a schematic block diagram of one embodiment of the depth dimming circuit 1 of this application. Figure 1 As shown, the depth dimming circuit 1 includes a dimming voltage signal terminal Vdim, a main control switch 10, a first dimming circuit 20, a second dimming circuit 30, and a switch control circuit 40. The dimming voltage signal terminal Vdim receives an externally input dimming voltage signal. The externally input dimming voltage signal is set to correspond to the brightness of the light-emitting element 2, and can be input via the operation switch of the light-emitting element 2, a touch switch, or a voice assistant. The main control switch 10 is electrically connected to the light-emitting element 2. The main control switch 10 controls the on / off state of the branch where the light-emitting element 2 is located. The first dimming circuit 20 is electrically connected to the dimming voltage signal terminal Vdim and the light-emitting element 2. The first dimming circuit 20 outputs a first control signal based on the dimming voltage signal. The second dimming circuit 30 includes a comparison circuit 31, electrically connected to the dimming voltage signal terminal Vdim, used to compare the dimming voltage signal and a voltage signal threshold, and output a second control signal. The voltage signal threshold can be a set voltage value and can be used as a reference signal for comparing the dimming voltage signal. The switch control circuit 40 is electrically connected to the first dimming circuit 20, the second dimming circuit 30, and the main control switch 10. The switch control circuit 40 is used to output a total control signal according to the first control signal and the second control signal to control the main control switch 10 to perform deep dimming on the light-emitting element 2.

[0038] In some embodiments, when the dimming voltage signal is not less than the voltage signal threshold, the total control signal changes with the change of the first control signal. At this time, the switch control circuit 40 controls the on / off state of the main control switch 10 through the first control signal to perform depth adjustment of the light-emitting element 2. In some embodiments, when the dimming voltage signal is less than the voltage signal threshold, the total control signal changes with at least the change of the second control signal. At this time, the switch control circuit 40 controls the on / off state of the main control switch 10 through at least the second control signal to perform depth adjustment of the light-emitting element 2. The depth dimming circuit 1 of this embodiment adopts a hybrid dimming method, combining the first control signal and the second control signal for depth dimming, which can solve the problem of insufficient dimming depth of the light-emitting element 2, achieving a simple circuit structure, low cost, and stable and reliable operation.

[0039] In some embodiments, the maximum depth of the light-emitting element 2 corresponding to the voltage signal threshold is 10%. For example, when the dimming voltage signal is not less than the voltage signal threshold, i.e., the dimming voltage signal is greater than 10% (e.g., 100% - 10%) of the LED depth, the depth dimming circuit 1 can use the first control signal of the first dimming circuit 20 as the total control signal to adjust the depth of the LED. When the dimming voltage signal is less than the voltage signal threshold, i.e., the dimming voltage signal is less than 10% of the LED depth, in some embodiments, the depth dimming circuit 1 can use the second control signal of the second dimming circuit 30 as the total control signal to adjust the depth of the LED. In other embodiments, the depth dimming circuit 1 can also use the control signal resulting from the combination of the first and second control signals as the total control signal to adjust the depth of the LED. With this setup, using the same depth dimming circuit 1 and a hybrid dimming method, the first control signal and the second control signal are combined for depth dimming. This not only allows for the adjustment of the depth of the light-emitting element 2 from 100% to 10%, but also allows for the adjustment of the depth of the light-emitting element 2 below 10%, thereby solving the problem of insufficient dimming depth of the light-emitting element 2. This results in a simple circuit structure, low cost, and stable and reliable operation.

[0040] In some embodiments, the first control signal is a PWM signal PWM1. When the dimming voltage signal is less than the voltage signal threshold, the second control signal is a square wave signal PWM2, and the duty cycle of the square wave signal PWM2 is different for different dimming voltage signals. The switch control circuit 40 is used to combine the PWM signal PWM1 and the square wave signal PWM2 to output a total control signal. In some embodiments, when the dimming voltage signal is not less than the voltage signal threshold, a total control signal with the same duty cycle as the PWM signal PWM1 is output. At this time, the switch control circuit 40 controls the on / off state of the main control switch 10 through the PWM signal PWM1 to perform depth adjustment of the light-emitting element 2. In some embodiments, when the dimming voltage signal is less than the voltage signal threshold, a total control signal is output by combining the PWM signal PWM1 and the square wave signal PWM2. At this time, the switch control circuit 40 controls the on / off state of the main control switch 10 by combining the PWM signal PWM1 and the square wave signal PWM2 to perform depth adjustment of the light-emitting element 2. In the above process, when the dimming voltage signal is not less than the voltage signal threshold, the square wave signal PWM2 is at a high level or a low level. The period of the square wave signal PWM2 is greater than the period of the PWM signal PWM1.

[0041] In this embodiment, when the dimming voltage signal is not less than 10% of the LED depth (i.e., greater than or equal to 10% of the LED depth), a total control signal with the same duty cycle as the PWM signal PWM1 is output to control the on / off state of the main control switch 10, thereby adjusting the depth of the LED. When the dimming voltage signal is less than 10% of the LED depth, a total control signal is output in combination with the PWM signal PWM1 and the square wave signal PWM2 to control the main control switch 10, thereby adjusting the depth of the LED. With this configuration, using the same depth dimming circuit 1 and employing a hybrid dimming method, the PWM signal PWM1 is combined with the square wave signal PWM2 containing duty cycle information for depth dimming. This not only adjusts the depth of the light-emitting element 2 from 100% to 10%, but also adjusts the depth of the light-emitting element 2 below 10%, thus solving the problem of insufficient dimming depth of the light-emitting element 2. This results in a simple circuit structure, low cost, and stable and reliable operation.

[0042] In some other embodiments, the first control signal is a PWM signal PWM1. When the dimming voltage signal is less than the voltage signal threshold, the second control signal is a square wave signal PWM2, and the duty cycle of the square wave signal PWM2 is different for different dimming voltage signals. The switch control circuit 40 is used to output a total control signal with the same duty cycle as the PWM signal PWM1 when the dimming voltage signal is not less than the voltage signal threshold. In this embodiment, when the dimming voltage signal is not less than 10% of the depth of the LED, the switch control circuit 40 outputs a total control signal with the same duty cycle as the PWM signal PWM1 to control the on / off state of the main control switch 10, so as to adjust the depth of the light-emitting element 2 from 10% to 100%. In some embodiments, when the dimming voltage signal is less than the voltage signal threshold, a total control signal with the same duty cycle as the square wave signal PWM2 is output. In this embodiment, when the dimming voltage signal is less than 10% of the LED depth, the switch control circuit 40 outputs a total control signal with the same duty cycle as the square wave signal PWM2 to control the on / off state of the main control switch 10, thereby adjusting the depth of the light-emitting element 2 below 10%. This configuration utilizes the same depth dimming circuit 1 to perform depth dimming on the PWM signal and the square wave signal containing duty cycle information, respectively. This not only adjusts the depth of the light-emitting element 2 from 100% to 10%, but also adjusts the depth below 10%, thus solving the problem of insufficient dimming depth of the light-emitting element 2. The circuit structure is simple, easy to implement, low in cost, and stable and reliable.

[0043] Figure 2 As shown Figure 1 A schematic block diagram of another embodiment of the depth dimming circuit 1 shown. Figure 2 As shown, the first dimming circuit 20 includes a sampling circuit 21, a signal control circuit 22, and an analog dimming circuit 23. The sampling circuit 21 is electrically connected to the light-emitting element 2 and is used to collect the current flowing through the light-emitting element 2 to generate a sampling voltage signal. The analog dimming circuit 23 is electrically connected to the dimming voltage signal terminal Vdim. The signal control circuit 22 is used to output a first control signal based on the sampling voltage signal and the dimming voltage signal. In this embodiment, the first control signal is a PWM signal PWM1. By setting the sampling circuit 21, the signal control circuit 22, and the analog dimming circuit 23, the first dimming circuit 20 outputs the PWM signal PWM1 when the dimming voltage signal is not less than 10% of the depth of the LED, thereby controlling the on / off state of the main control switch 10 to achieve depth adjustment of the light-emitting element 2 from 10% to 100%. This adjustment method is fast and efficient, with a simple circuit structure and low cost.

[0044] exist Figure 2In the illustrated embodiment, the second dimming circuit 30 further includes a sawtooth wave generation circuit 32. The sawtooth wave generation circuit 32 generates a sawtooth wave voltage signal. The voltage signal threshold is the maximum value of the sawtooth wave voltage signal. The comparison circuit 31 includes a first input terminal 311, a second input terminal 312, and an output terminal 313. The dimming voltage signal terminal Vdim is electrically connected to the first input terminal 311, the sawtooth wave generation circuit 32 is electrically connected to the second input terminal 312, and the output terminal 313 is electrically connected to the switch control circuit 40. The comparison circuit 31 compares the dimming voltage signal with the maximum value of the sawtooth wave voltage signal to output a second control signal. In this embodiment, when the dimming voltage signal is less than the voltage signal threshold, the second control signal is a square wave signal PWM2. The duty cycle of the square wave signal PWM2 varies depending on the dimming voltage signal. The sawtooth wave voltage signal generated by the sawtooth wave generation circuit 32 is used as a reference voltage for the dimming voltage signal. The sawtooth wave voltage signal is easy to generate and has continuous and linear variation characteristics, making it easy to analyze and process. When the dimming voltage signal is less than 10% of the LED depth, the comparator circuit 31 compares the maximum value of the sawtooth wave voltage signal as the reference voltage of the dimming voltage signal to output a square wave signal PWM2. That is, by generating a fixed sawtooth wave signal and comparing it with the dimming voltage signal, a square wave signal PWM2 containing duty cycle information is generated to control the main control switch 10, thereby controlling the depth adjustment of the light-emitting element 2 below 10%, thus solving the problem of difficulty in adjusting the depth of the light-emitting element 2 below 10%. Moreover, by generating the square wave signal PWM2 from the sawtooth wave signal, the circuit structure is simple, low-cost, stable and reliable.

[0045] exist Figure 2 In the illustrated embodiment, the sampling circuit 21 includes a sampling resistor Rcs connected in series with the light-emitting element 2. Using the sampling resistor Rcs as the sampling element allows for the acquisition of an accurate current signal, resulting in a more precise, stable, and reliable sampling signal at a low cost. In some embodiments, the depth dimming circuit 1 includes an inductor L connected in series with the light-emitting element 2. When the inductor L is connected in series with the light-emitting element 2, the inductor L can absorb and regulate energy in the circuit to smooth the current, preventing sudden current changes from damaging the light-emitting element 2, thus ensuring stable operation and extending its lifespan. In some embodiments, the depth dimming circuit 1 includes a freewheeling diode D connected in series with the light-emitting element 2. The freewheeling diode D primarily prevents high-voltage pulses caused by sudden current changes in the light-emitting element 2, ensuring stable circuit operation.

[0046] Specifically, in Figure 2 In the illustrated embodiment, the light-emitting element 2, the sampling resistor Rcs, the inductor L, and the freewheeling diode D are connected in series, and the sampling resistor Rcs is located at the negative terminal of the light-emitting element 2. Figure 2In the illustrated embodiment, the comparison circuit 31 includes a comparator. The comparator includes a non-inverting input, an inverting input, and an output. The first input 311 of the comparison circuit 31 can be the non-inverting input of the comparator, the second input 312 can be the inverting input of the comparator, and the output 313 of the comparison circuit 31 can be the output of the comparator. Figure 2 In the illustrated embodiment, the main control switch 10 includes an N-type MOSFET. The first terminal of the N-type MOSFET can be the gate, which is electrically connected to the output terminal of the comparator. The second terminal of the N-type MOSFET can be the drain, which is electrically connected to the inductor L. The third terminal of the N-type MOSFET can be the source, which is electrically connected to the ground terminal GND.

[0047] exist Figure 2 In the illustrated embodiment, the switch control circuit 40 includes an AND logic circuit 41. The AND logic circuit 41 includes a first access terminal 411, a second access terminal 412, and an operational output terminal 413. The first access terminal 411 is electrically connected to the first dimming circuit 20, the second access terminal 412 is electrically connected to the second dimming circuit 30, and the operational output terminal 413 is electrically connected to the main control switch 10. The AND logic circuit 41 is used to perform a logical AND operation on the first control signal and the second control signal. In this embodiment, the first control signal is a PWM signal PWM1. When the dimming voltage signal is less than the voltage signal threshold, the second control signal is a square wave signal PWM2. The duty cycle of the square wave signal PWM2 varies depending on the dimming voltage signal. The first access terminal 411 is electrically connected to the signal control circuit 22, and the second access terminal 412 is electrically connected to the output terminal of the comparator. By performing a logical AND operation on the PWM signal PWM1 and the square wave signal PWM2 with the logic circuit 41, for example, when performing a logical AND operation on a PWM signal PWM1 and a square wave signal PWM2, the output will only be high when both signals are high. This can be used to eliminate certain noise or unwanted signals, thus precisely controlling the on / off state of the main control switch 10 and accurately controlling the depth of the light-emitting element 2.

[0048] Figure 3 As shown Figure 2 The diagram shows a signal waveform of the depth dimming circuit 1. Figure 4 As shown Figure 2 Another signal waveform diagram of the depth dimming circuit is shown. Combined with... Figures 2 to 4As shown, the first control signal is the PWM signal PWM1. When the dimming voltage signal is less than the voltage signal threshold, the second control signal is the square wave signal PWM2. The duty cycle of the square wave signal PWM2 is different depending on the dimming voltage signal. The sampling circuit 21 samples the current flowing through the inductor L on the sampling resistor Rcs. The analog dimming circuit 23 uses analog dimming to achieve dimming depth of 10%-100% for the light-emitting element 2. Vdim is the externally input dimming voltage signal. The signal control circuit 22 generates the PWM signal PWM1 to control the main control switch 10 by acquiring the current sampling signal and the analog dimming signal. Meanwhile, when the dimming voltage signal Vdim is small, that is, when the dimming depth is set to be less than 10%, the dimming voltage signal Vdim is compared with the sawtooth wave signal generated by the sawtooth wave generation circuit 32 to obtain a square wave signal PWM2 containing duty cycle information. The period of the square wave signal PWM2 is greater than the period of the PWM signal PWM1. After performing an AND logic operation on the PWM signal PWM1 and the square wave signal PWM2, the control signal of the main control switch 10 is obtained to realize the depth adjustment of the light-emitting element 2.

[0049] Specifically, in Figures 2 to 4 In the illustrated embodiment, when the dimming voltage signal is not less than 10% of the depth of the LED (i.e., greater than or equal to 10% of the depth of the LED), the dimming voltage signal Vdim is always greater than the peak value of the sawtooth wave signal. Therefore, the output of the comparator is always a high-level square wave signal PWM2, and the switching control circuit 40 depends on the PWM signal PWM1. At this time, dimming is performed through the first dimming circuit 20, that is, the light-emitting element 2 is dimmed to a certain depth through analog dimming. The dimming accuracy and linearity at this time depend on the accuracy and linearity of the analog dimming circuit 23.

[0050] When the dimming voltage signal drops to 10% of the LED depth, the depth dimming circuit 1 is in a critical state between two dimming modes. The PWM signal PWM1 generated by the first dimming circuit 20 is required to ensure that the depth dimming circuit 1 operates in CCM (Continuous Conduction Mode). The main control switch 10 of the depth dimming circuit 1 is still controlled by the PWM signal PWM1, and the average current of the inductor L at this time is IL0.

[0051] When the dimming voltage signal is less than 10% of the depth of the LED, the analog dimming circuit 23 outputs a fixed dimming signal, that is, generates a fixed PWM signal PWM1. Therefore, the change of the logic circuit 41 at this time mainly depends on the change of the square wave signal PWM2.

[0052] exist Figure 3In the illustrated embodiment, the maximum voltage of the sawtooth wave signal is Vp, the minimum voltage is 0, Vdim is the dimming voltage signal, T is the period of the sawtooth wave signal, and D is the duty cycle of the sawtooth wave signal. The expression for the duty cycle D can be calculated as follows:

[0053]

[0054] From the above equation, it can be seen that D and Vdim have a linear relationship. At the same time, D determines the average current of inductor L, resulting in the final expression for the current of inductor L:

[0055]

[0056] Since both IL0 and Vp are constant values, the average current of inductor L is linearly related to the dimming voltage Vdim in deep dimming mode, ensuring the linearity of dimming under deep dimming conditions and realizing deep dimming. Compared with the single dimming technology of related technologies, this embodiment generates sawtooth wave signals by adding a sawtooth wave generation circuit 32. The circuit structure is simple, stable, reliable, and low in cost.

[0057] Figure 5 As shown Figure 2 The circuit diagram of the second adjustment circuit 30 of the depth dimming circuit 1 is shown. Figure 4As shown, in some embodiments, the sawtooth wave generating circuit 32 includes a sawtooth wave voltage signal terminal ST, a hysteresis comparator circuit 321, and an adjustment switch 322. The sawtooth wave voltage signal terminal ST is electrically connected to the comparator circuit 31. Specifically, the sawtooth wave voltage signal terminal ST is electrically connected to the second input terminal 312 for outputting a sawtooth wave voltage signal. The adjustment switch 322 is electrically connected between the sawtooth wave voltage signal terminal ST and the ground terminal GND. The hysteresis comparator circuit 321 is electrically connected between the sawtooth wave voltage signal terminal ST and the adjustment switch 322. The hysteresis comparator circuit 321 includes an upper threshold and a lower threshold. The hysteresis comparator circuit 321 is used to compare the sawtooth wave voltage signal with the upper threshold VH and the lower threshold VL respectively, and output an adjustment signal to control the adjustment switch 322. In this embodiment, the hysteresis comparator circuit 321 includes a signal input terminal and a signal output terminal. The signal input terminal is connected to the sawtooth wave voltage signal terminal ST, and the signal output terminal is connected to the adjustment switch 322. In this embodiment, the hysteresis comparator circuit 321 includes a hysteresis comparator. The hysteresis comparator includes an upper threshold VH and a lower threshold VL. In this embodiment, the regulating switch 322 includes an N-type MOSFET. The first terminal of the N-type MOSFET can be the gate, electrically connected to the signal output terminal of the hysteresis comparator; the second terminal of the N-type MOSFET can be the drain, electrically connected to the sawtooth wave voltage signal terminal ST; and the third terminal of the N-type MOSFET can be the source, electrically connected to the ground terminal GND. By setting the hysteresis comparator circuit 321 and the regulating switch 322 in conjunction with the sawtooth wave voltage signal terminal ST, a sawtooth wave signal is output. This circuit structure and implementation are simple, stable, reliable, and low in cost.

[0058] exist Figure 5 In the illustrated embodiment, the depth dimming circuit 1 includes a power supply terminal VDD. The sawtooth wave generation circuit 32 includes an adjustment branch 323, which includes a resistor R and a capacitor C, connected in series between the power supply terminal VDD and the ground terminal GND. The sawtooth wave voltage signal terminal ST is electrically connected between the resistor R and the capacitor C. In this embodiment, the capacitor C helps stabilize the voltage, making the output signal smoother and more stable. The resistor R limits the current flow in the circuit, acting as a current limiter. Through the combined use of the capacitor C and the resistor R, the stability of the sawtooth wave signal generated by the sawtooth wave generation circuit 32 is improved.

[0059] In this embodiment, the power supply terminal VDD provides the power voltage to charge capacitor C, causing the voltage at the sawtooth wave voltage signal terminal ST to rise. When the voltage increases above the upper threshold VH, the hysteresis comparator outputs a high level, controlling the regulating switch 322 to turn on and pull the voltage at the sawtooth wave voltage signal terminal ST down. When the voltage at the sawtooth wave voltage signal terminal ST decreases below the lower threshold VL, the hysteresis comparator outputs a low level, controlling the regulating switch 322 to turn off, and the power supply voltage continues to charge capacitor C, causing the voltage at the sawtooth wave voltage signal terminal ST to rise, repeating the working cycle. Using the capacitor charging and discharging formula, the period of the sawtooth wave signal can be obtained as:

[0060]

[0061] With this configuration, the sawtooth wave generation circuit 32 can generate a sawtooth wave signal with a certain period. The circuit structure is simple, requires no additional external circuits, can be integrated into the chip, saves circuit costs, and has high stability.

[0062] Figure 6 As shown Figure 2 The circuit diagram shows another embodiment of the depth dimming circuit 1. Figure 6 The illustrated embodiments and Figure 2 The embodiments shown are similar. Figure 2 and Figure 6 The depth dimming circuits 1 shown are all step-down circuits. The main difference lies in the connection relationships of the light-emitting element 2, sampling resistor Rcs, inductor L, freewheeling diode D, and main control switch 10. Figure 6 In the illustrated embodiment, the sampling resistor Rcs is electrically connected between the light-emitting element 2 and the ground terminal GND, and the sampling resistor Rcs is located at the negative terminal of the light-emitting element 2. The first terminal of the N-type MOSFET is electrically connected to the output terminal of the switch control circuit 40, the third terminal of the N-type MOSFET is electrically connected to the inductor L, and the second terminal of the N-type MOSFET is electrically connected to the branch where the light-emitting element 2 is located. The inductor L is electrically connected between the source of the N-type MOSFET and the light-emitting element 2, the anode of the freewheeling diode D is electrically connected to the ground terminal GND, and the cathode of the freewheeling diode D is electrically connected to the inductor L. With this configuration, the depth dimming circuit 1 can be applied to... Figure 6 The circuit structure diagram of the depth dimming circuit 1 shown is used to achieve depth control of the light-emitting element 2, which is highly adaptable.

[0063] Figure 7 As shown Figure 2 A circuit diagram of another embodiment of the depth dimming circuit 1 shown. Figure 7 The illustrated embodiments and Figure 2 The embodiments shown are similar, the main difference being that, Figure 7The depth dimming circuit shown is a boost circuit, and the connection relationships of its light-emitting element 2, sampling resistor Rcs, inductor L, and freewheeling diode D are different. Figure 7 In the illustrated embodiment, the inductor L, freewheeling diode D, light-emitting element 2, and sampling resistor Rcs are connected in series. The sampling resistor Rcs is located at the negative terminal of the light-emitting element 2, and one end of the sampling resistor Rcs is connected to the ground terminal GND. With this configuration, the depth dimming circuit 1 can be applied to... Figure 7 The circuit structure diagram of the depth dimming circuit 1 shown is used to achieve depth adjustment of the light-emitting element 2, which is highly adaptable.

[0064] In other embodiments, the depth dimming circuit 1 can also be adapted to other circuit structures, and is not limited to those specified in the original text. Figure 2 , Figure 6 and Figure 7 The circuit structure shown is shown.

[0065] In the above scheme, the depth dimming circuit 1 provided in this embodiment does not require complex circuits or an additional PWM signal PWM1 generated by an MCU. This depth dimming circuit 1 adopts a hybrid dimming method. When dimming from 100% to 10% brightness, it uses an analog dimming mode. When dimming below 10%, it compares the dimming signal voltage with a fixed sawtooth wave signal to obtain a square wave signal PWM2 with dimming duty cycle information. This square wave signal PWM2 is then combined with the overall circuit switching signal to control the circuit, achieving depth dimming below 10%. With this configuration, this application utilizes the same depth dimming circuit 1 to adjust not only the depth adjustment of the light-emitting element 2 from 100% to 10%, but also the depth adjustment below 10%, thus solving the problem of insufficient dimming depth of the light-emitting element 2. This results in a simple circuit structure that is easy to implement, low in cost, and stable and reliable.

[0066] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A deep dimming circuit for a light emitting element, characterized by, The application relates to a light-emitting device, which comprises the following parts: a dimming voltage signal terminal for receiving an externally input dimming voltage signal; a main control switch electrically connected with the light-emitting element; a first dimming circuit electrically connected with the dimming voltage signal terminal and the light-emitting element; the first dimming circuit is used for outputting a first control signal based on the dimming voltage signal; a second dimming circuit comprising a comparison circuit, which is electrically connected with the dimming voltage signal terminal and is used for comparing the dimming voltage signal with a voltage signal threshold value and outputting a second control signal; a switch control circuit electrically connected with the first dimming circuit, the second dimming circuit and the main control switch, which is used for outputting a total control signal according to the first control signal and the second control signal and controlling the main control switch to deeply dim the light-emitting element; wherein when the dimming voltage signal is not less than the voltage signal threshold value, the total control signal changes with the change of the first control signal, and when the dimming voltage signal is less than the voltage signal threshold value, the total control signal at least changes with the change of the second control signal. The first control signal is a PWM signal; when the dimming voltage signal is less than the voltage signal threshold value, the second control signal is a square wave signal, the dimming voltage signal is different from the duty ratio of the square wave signal; the switch control circuit is used for combining the PWM signal and the square wave signal to output the total control signal; wherein when the dimming voltage signal is not less than the voltage signal threshold value, the total control signal outputted is consistent with the duty ratio of the PWM signal, and when the dimming voltage signal is less than the voltage signal threshold value, the total control signal is outputted by combining the PWM signal and the square wave signal; wherein when the dimming voltage signal is not less than the voltage signal threshold value, the square wave signal is a high level or a low level, and the period of the square wave signal is greater than the period of the PWM signal.

2. The deep dimming circuit of claim 1, wherein, The first control signal is a PWM signal; when the dimming voltage signal is less than the voltage signal threshold value, the second control signal is a square wave signal, the dimming voltage signal is different from the duty ratio of the square wave signal; the switch control circuit is used for outputting the total control signal consistent with the duty ratio of the PWM signal when the dimming voltage signal is not less than the voltage signal threshold value, and outputting the total control signal consistent with the duty ratio of the square wave signal when the dimming voltage signal is less than the voltage signal threshold value.

3. The deep dimming circuit of claim 1, wherein, The second dimming circuit further comprises a sawtooth wave generating circuit, which is used for generating a sawtooth wave voltage signal, and the voltage signal threshold value is the maximum value of the sawtooth wave voltage signal.

4. The deep dimming circuit of claim 1, wherein, The sawtooth wave generating circuit comprises:

5. The deep dimming circuit of claim 4, wherein, a sawtooth wave voltage signal terminal electrically connected with the comparison circuit and used for outputting the sawtooth wave voltage signal; an adjusting switch electrically connected between the sawtooth wave voltage signal terminal and a ground terminal; ​ A hysteresis comparison circuit is electrically connected between the sawtooth voltage signal terminal and the regulating switch, and includes an upper threshold and a lower threshold. The hysteresis comparison circuit is configured to compare the sawtooth voltage signal with the upper threshold and the lower threshold respectively, and output a regulating signal to control the regulating switch.

6. The deep dimming circuit of claim 5, wherein, The deep dimming circuit includes a power supply terminal. The sawtooth wave generating circuit includes a regulating branch, which includes a resistor and a capacitor connected in series between the power supply terminal and the ground terminal. The sawtooth voltage signal terminal is electrically connected between the resistor and the capacitor. And / or The hysteresis comparison circuit includes a hysteresis comparator. And / or The regulating switch includes an N-type MOS transistor.

7. The deep dimming circuit of claim 1, wherein, The first dimming circuit includes a sampling circuit, a signal control circuit and an analog dimming circuit. The sampling circuit is electrically connected to the light emitting element, configured to collect the current flowing through the light emitting element to generate a sampling voltage signal. The analog dimming circuit is electrically connected to the dimming voltage signal terminal. The signal control circuit is configured to output the first control signal according to the sampling voltage signal and the dimming voltage signal.

8. The deep dimming circuit of claim 7, wherein, The sampling circuit includes a sampling resistor connected in series with the light emitting element. And / or The deep dimming circuit includes an inductor connected in series with the light emitting element. And / or The deep dimming circuit includes a freewheeling diode connected in series with the light emitting element.

9. The deep dimming circuit of claim 1, wherein, The switch control circuit includes an AND logic circuit having a first input terminal, a second input terminal and an operation output terminal. The first input terminal is electrically connected to the first dimming circuit. The second input terminal is electrically connected to the second dimming circuit. The operation output terminal is electrically connected to the main control switch. The AND logic circuit is configured to perform logical AND operation on the first control signal and the second control signal.

10. The deep dimming circuit of claim 1, wherein, The maximum depth of the light emitting element corresponding to the voltage signal threshold is 10%.

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