CN113242626A

CN113242626A - Dimming control circuit and system

Info

Publication number: CN113242626A
Application number: CN202110581795.XA
Authority: CN
Inventors: 张攀
Original assignee: MAXIC TECHNOLOGY (BEIJING) CO LTD
Current assignee: MAXIC TECHNOLOGY (BEIJING) CO LTD
Priority date: 2021-05-26
Filing date: 2021-05-26
Publication date: 2021-08-10

Abstract

The application provides a dimming control circuit and a system, wherein the dimming control circuit comprises a ripple filtering unit and at least one load unit, the ripple filtering unit is respectively connected with each load unit in series, and the ripple filtering unit is used for removing current ripples of each load unit; and each dimming control unit is correspondingly connected with one load unit, the number of the dimming control units is the same as that of the load units, and the dimming control units are used for adjusting the voltage obtained by the connected load units according to the received PWM signals so as to adjust the brightness.

Description

Dimming control circuit and system

Technical Field

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

Background

Currently, a conventional dimming control circuit is shown in fig. 1, which combines a non-strobe PWM smart dimming circuit with a charging loop and a main power constant current loop. In conventional circuits, the charging loop charges the capacitor C, which causes additional losses since the current does not flow through the LED. Therefore, the ineffective loss of the whole LED dimming control circuit is large, so that the efficiency thereof is low. And the charging loop also needs two diodes to set a current path, thereby causing waste of cost.

Disclosure of Invention

An object of the embodiments of the present application is to provide a dimming control circuit and system, so as to solve the above problem.

In a first aspect, the present invention provides a dimming control circuit, including: the ripple filtering unit is respectively connected with each load unit in series and is used for removing current ripples of each load unit; each dimming control unit is correspondingly connected with one load unit, the number of the dimming control units is the same as that of the load units, and the dimming control units are used for adjusting the voltage obtained by the connected load units according to the received PWM signals so as to adjust the brightness.

The dimming control circuit is designed to filter the current ripple of each load unit based on the ripple filtering unit, so that the stroboscopic of each load unit is eliminated; and adjust the luminance of the load unit that corresponds the connection through every control unit that adjusts luminance according to the PWM signal that receives for the control circuit that adjusts luminance that the application designed only adopts a control unit loop that adjusts luminance can realize not having the stroboscopic and adjust luminance, has abandoned the charge loop in the traditional circuit, thereby has eliminated the loss that the charge loop brought in the traditional circuit, and has left out numerous components and parts in the charge loop, the cost is reduced.

In an optional implementation manner of the first aspect, the number of the load units and the number of the dimming control units are both one, and the dimming control unit is connected in series with the ripple filtering unit and then connected in series with the load unit.

In an optional implementation manner of the first aspect, the ripple filtering unit includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and a capacitor C2, a control end of the controllable switch tube M1 is connected to the capacitor C1 and then connected to the second end of the controllable switch tube M1, a control end of the controllable switch tube M1 is connected to an anode of the zener diode Q1, a cathode of the zener diode Q1 is connected to a cathode of the load unit in series with the resistor R1 and then connected to a cathode of the load unit, a first end of the controllable switch tube M1 is connected to a cathode of the load unit, an anode of the load unit is connected to the second end of the controllable switch tube M1 through the capacitor C2, and the dimming control unit is connected to the second end of the controllable switch tube M1.

In an optional embodiment of the first aspect, the load unit and the dimming control unit are both one in number, and the load unit is connected in series between the dimming control unit and the ripple filtering unit.

In an optional implementation manner of the first aspect, the ripple filtering unit includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and a capacitor C2, a second end of the controllable switch tube M1 is connected to an anode of the load unit, a first end of the controllable switch tube M1 is connected in series with the capacitor C2 and then connected to a cathode of the load unit, a control end of the controllable switch tube M1 is connected in series with the capacitor C1 and then connected to a second end of the controllable switch tube M1, a control end of the controllable switch tube M1 is connected to an anode of the zener diode Q1, a cathode of the zener diode Q1 is connected in series with the resistor R1 and then connected to a first end of the controllable switch tube M1, and the dimming control unit is connected to the cathode of the load unit.

In an optional implementation manner of the first aspect, the number of the load units and the number of the dimming control units are multiple, and each dimming control unit is connected in series with one load unit correspondingly and then connected in series with the ripple filtering unit.

In an alternative embodiment of the first aspect, the ripple filtering unit includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and a plurality of capacitors C2, a second end of the controllable switch tube M1 is connected to an anode of each load unit, a cathode of each load unit is connected in series to a capacitor C2 and then connected to a first end of the controllable switch tube M1, a control end of the controllable switch tube M1 is connected in series to a capacitor C1 and then connected to a second end of the controllable switch tube M1, a control end of the controllable switch tube M1 is connected to an anode of the zener diode Q1, a cathode of the zener diode Q1 is connected in series to a resistor R1 and then connected to a first end of the controllable switch tube M1, and each dimming control unit is connected to a cathode of one load unit.

In the embodiment of the above design, the plurality of load units share one ripple filtering unit, so that the purposes of saving cost and simplifying circuits are achieved while achieving non-strobe dimming of the plurality of loads.

In an optional implementation manner of the first aspect, each of the dimming control units includes a PWM subunit, a reference modulation subunit, an integrating circuit, a power control subunit, a controllable switch tube M2, and a resistor R2, where the PWM subunit, the reference modulation subunit, the integrating circuit, and the power control subunit are connected in series in sequence, the power control subunit is connected to a control end of the controllable switch tube M2, a second end of the controllable switch tube M2 is connected to the integrating circuit and is grounded through the resistor R2, and a first end of the controllable switch tube M2 is connected to a corresponding load unit; the PWM subunit is used for receiving the PWM signal and outputting a level signal corresponding to the PWM signal to the reference modulation subunit according to the PWM signal; the reference modulation subunit is used for determining a voltage value transmitted to the integrating circuit according to the received level signal; the integrating circuit is used for outputting an integrating signal to the power control subunit according to the voltage value received by the positive phase input end and the feedback voltage received by the negative phase input end; and the power control subunit is used for adjusting the voltage obtained by dividing the resistor R2 according to the integrated signal.

In an alternative implementation of the first aspect, the PWM subunit comprises an operational amplifier L1, the reference modulation subunit comprises an inverter a1, an inverter a2, a controllable switch K1, and a controllable switch K2, the integration circuit comprises an integrator G1 and a capacitor C3, and the power control subunit comprises an operational amplifier L2; a non-inverting input terminal of the operational amplifier L1 is configured to receive the PWM signal, an inverting input terminal of the operational amplifier L1 is configured to receive a first reference voltage, and an output terminal of the operational amplifier L1 is connected to an input terminal of the inverter a 1; the output end of the inverter A1 is connected with the input end of the inverter A2, the output end of the inverter A2 is connected with the control end of the controllable switch K1, the input end of the controllable switch K1 is connected with a second reference voltage, the output end of the controllable switch K1 is connected with the positive input end of the integrator G1, the output end of the inverter A1 is further connected with the control end of the controllable switch K2, the input end of the controllable switch K2 is grounded, and the output end of the controllable switch K2 is connected with the output end of the controllable switch K1; the inverting input end of the integrator G1 is connected with the second end of the controllable switch tube M2, the output end of the integrator G1 is connected with the non-inverting input end of the operational amplifier L2, and the output end of the integrator G1 is also grounded through a capacitor C3; the inverting input end of the operational amplifier L2 is connected to the second end of the controllable switch tube M2, and the output end of the operational amplifier L2 is connected to the control end of the controllable switch tube M2.

In the embodiment designed above, based on the combination of the ripple filtering unit and the dimming control unit, the voltage at the first end of the controllable switching tube M2 changes with the change of the bus voltage instead of being continuously maintained at a high value as in the conventional manner, thereby reducing the loss of the dimming control unit and improving the efficiency of the entire dimming control circuit.

In an optional implementation manner of the first aspect, each of the dimming control units further includes a bus sampling subunit and a current compensation subunit, the bus sampling subunit is connected to the current compensation subunit, and the current compensation subunit is connected to the power control subunit; the bus sampling subunit is used for sampling a bus voltage signal and transmitting the bus voltage signal to the current compensation subunit; the current compensation subunit is used for generating a corresponding compensation signal according to the bus voltage signal and transmitting the compensation signal to the power control subunit; the power control subunit is further configured to compensate the current of the resistor R2 according to the compensation signal, so that the current of the resistor R2 is in an inverse relationship with the bus current, and the power consumption of the resistor R2 is further reduced.

In an alternative implementation manner of the first aspect, the bus sampling subunit comprises a resistor R3 and a resistor R4, the current compensation subunit comprises an operational amplifier L3, a MOS transistor M3, a MOS transistor M4, the power supply circuit comprises a MOS tube M5, a resistor R5 and a resistor R6, wherein the resistor R3 and the resistor R4 are connected in series and then are respectively connected with the second end and the grounding end of a controllable switching tube M1, the positive phase input end of an operational amplifier L3 is connected between the resistor R3 and the resistor R4, the negative phase input end of an operational amplifier L3 is grounded through a resistor R5, the output end of the operational amplifier L3 is connected with the gate of the MOS tube M3, the source of the MOS tube M3 is connected with the negative phase input end of the operational amplifier L3, the drain of the MOS tube M3 is connected with the drain of the MOS tube M4, the drain of the MOS tube M4 is further connected with the gate of the MOS tube M4, the source of the MOS tube M4 is connected with the source of the MOS tube M5, the gate of the MOS tube M4 is connected with the gate of the MOS tube M5, and the drain of the MOS tube M5 is connected with a power control subunit and connected with the resistor R2 through a resistor R6.

In the embodiment designed above, the bus sampling subunit and the current compensation subunit make the current of the resistor R2 and the change of the bus voltage have an inverse relationship, thereby improving the efficiency of the whole dimming control circuit.

In a second aspect, the present invention provides a dimming control system, comprising: as in any optional implementation manner of the first aspect, the dimming control circuit, the rectifying unit, and the power supply are connected to the dimming control circuit through the rectifying unit.

In the dimming control system designed above, because the dimming control system is designed based on the dimming control circuit in the first embodiment, it can implement non-strobe dimming only by using one loop of the dimming control unit, and abandons the charging loop in the conventional circuit, thereby eliminating the loss caused by the charging loop in the conventional circuit, and omitting numerous components in the charging loop, and reducing the cost.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used 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 therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

Fig. 1 is a schematic structural diagram of a conventional circuit provided in an embodiment of the present application;

fig. 2 is a schematic diagram of a first structure of a dimming control circuit according to an embodiment of the present disclosure;

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

fig. 4 is a schematic diagram of a third structure of a dimming control circuit according to an embodiment of the present application;

fig. 5 is a fourth schematic structural diagram of a dimming control circuit according to an embodiment of the present application;

fig. 6 is a fifth structural schematic diagram of a dimming control circuit according to an embodiment of the present application;

fig. 7 is a sixth schematic diagram of a dimming control circuit according to an embodiment of the present application;

fig. 8 is a schematic diagram illustrating a seventh structure of a dimming control circuit according to an embodiment of the present application;

fig. 9 is an eighth schematic structural diagram of a dimming control circuit according to an embodiment of the present application;

fig. 10 is a schematic diagram of a ninth structure of a dimming control circuit according to an embodiment of the present application;

fig. 11 is a tenth structural schematic diagram of a dimming control circuit according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of a dimming control system according to an embodiment of the present application.

Icon: 1-a dimming control circuit; 2-a rectifying unit; 3-a power supply; 10-ripple filtering unit; 20-a load cell; 30-a dimming control unit; 301-PWM subunit; 302-a reference modulation subunit; 303-an integrating circuit; 304-a power control subunit; 305-a bus sampling subunit; 306-current compensation subunit.

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.

First embodiment

The embodiment of the present application provides a dimming control circuit, which includes a ripple filtering unit 10, at least one load unit 20, and at least one dimming control unit 30. The ripple filtering unit 10 is connected in series with each load unit 20. Each dimming control unit 30 is connected to one load unit 20. Based on the dimming control circuit, the current ripple generated by each load unit 20 connected in series is filtered based on the ripple filtering unit, so that the stroboscopic of each load unit is eliminated; each dimming control unit 30 can adjust the brightness of the corresponding connected load unit according to the received PWM signal, so that the dimming control circuit designed in the present application has only one loop of the dimming control unit 30 on the basis of implementing non-strobe dimming. Therefore, a charging loop in a traditional circuit is abandoned, the loss caused by the charging loop in the traditional circuit is eliminated, and a plurality of components in the charging loop are omitted, so that the cost is reduced.

In an optional implementation manner of this embodiment, the load unit 20 is correspondingly connected to the dimming control unit 30, which may specifically include the following different connection manners: as a possible embodiment, the dimming control unit 30 is connected in series with the ripple filtering unit 10 and then connected in series with the corresponding load unit 20. As another possible embodiment, the dimming control unit 30 may be directly connected in series with the corresponding load unit 20 and then connected in series with the ripple filtering unit 10.

In the first embodiment, the dimming control unit 30 is connected in series with the ripple filtering unit 10 and then connected in series with the corresponding load unit 20. As shown in fig. 2, the dimming control unit 30 and the load unit 20 designed in the present application may be respectively one in number, where the load unit 20 may specifically be an LED display unit or other display units including a plurality of light emitting diodes connected in series in sequence, and fig. 2 is a diagram taking the LED display unit as an example.

On the basis of the above connection structure, the present application designs a circuit structure as shown in fig. 3 to implement the above structure specifically, in the design of this embodiment, the ripple filtering unit 10 may include a capacitor C1, a controllable switch transistor M1, a zener diode Q1, a resistor R1, and a capacitor C2, where the controllable switch transistor M1 may be a controllable switch transistor such as a MOS transistor or a triode, and fig. 3 is an exemplary diagram in which the controllable switch transistor M1 is a MOS transistor.

The gate of the controllable switch M1 is connected to the capacitor C1 and then to the source of the controllable switch M1. The gate of the controllable switch M1 is connected to the anode of the zener diode Q1. The cathode of the zener diode Q1 is connected in series with the resistor R1 and then connected to the cathode of the load unit 20. The drain of the controllable switching transistor M1 is connected to the negative terminal of the load cell 20. The anode of the load unit is connected to the source of the controllable switch transistor M1 through a capacitor C2. The source of the controllable switch M1 is connected to the dimming control unit 30.

When the circuit designed above is applied, the stroboscopic elimination principle is as follows: the positive electrode of the load unit 20 and the dimming control unit 30 are connected to a power supply, respectively, so that the circuits form a loop. In an application process, the voltage across the capacitor C2 includes an alternating current component, the ripple filtering unit 10 samples the voltage across the capacitor C2, and filters the sampled signal through the capacitor C1, the zener diode Q1, and the resistor R1, so that the gate voltage of the MOS transistor M1 is a direct current voltage, the zener diode Q1 is used to adjust the drain voltage of the MOS transistor M1, and make the MOS transistor M1 work in a saturation region, so that the current flowing through the MOS transistor M1 is constant, and the MOS transistor M1 and the load unit 20 are in a series relationship, so that the current flowing through the LED load unit is also constant, that is, the current flowing through the LED display unit 20 does not include an alternating current component, and further, the stroboscopic phenomenon of the load unit 20 is eliminated.

It should be noted here that when the ripple is relatively small, the zener diode Q1 may be omitted; when the ripple is great, can realize effectively getting rid of great ripple through the zener diode Q1 of a certain amount of series stack, the realization circuit of the above-mentioned ripple filtering unit 10 is only a ripple filtering, except the ripple filtering circuit of above-mentioned structure, this application can also be other circuit structures that have the ripple elimination function.

In the second embodiment, that is, the dimming control unit 30 is directly connected in series with the corresponding load unit 20 and then connected in series with the ripple filtering unit 10, the numbers of the dimming control unit 30 and the load unit 20 designed according to the present application may be one or more, the components of the ripple filtering unit 10 are the same as those of the above components, and when the numbers of the dimming control unit 30 and the load unit 20 are one, the circuit structure thereof is as shown in fig. 4 and 5:

the source of the controllable switch tube M1 is connected to the positive electrode of the load unit 20, the drain of the controllable switch tube M1 is connected in series with the capacitor C2 and then connected to the negative electrode of the load unit 20, the gate of the controllable switch tube M1 is connected in series with the capacitor C1 and then connected to the source of the controllable switch tube M1, the gate of the controllable switch tube M1 is connected to the anode of the zener diode Q1, the cathode of the zener diode Q1 is connected in series with the resistor R1 and then connected to the drain of the controllable switch tube M1, and the dimming control unit 30 is connected to the negative electrode of the load unit 20.

When the dimming control unit 30 and the load unit 20 are multiple in number, the number of capacitors C2 in the components of the ripple filtering unit 10 may be the same as the number of the dimming control unit 30, and the remaining components are the same as those described above, and the circuit structure thereof is as shown in fig. 6 and 7:

the source of the controllable switch tube M1 is connected to the anode of each load unit 20, the cathode of each load unit 20 is connected in series with a capacitor C2 and then connected to the source of the controllable switch tube M1, the gate of the controllable switch tube M1 is connected in series with a capacitor C1 and then connected to the source of the controllable switch tube M1, the gate of the controllable switch tube M1 is connected to the anode of the zener diode Q1, the cathode of the zener diode Q1 is connected in series with a resistor R1 and then connected to the drain of the controllable switch tube M1, and each dimming control unit 30 is correspondingly connected to the cathode of one load unit 20.

In the structure of fig. 7, since the ripple filtering unit 10 filters the current ripple of the bus current and then transmits the filtered current ripple to each load unit 20, in such a case, the plurality of load units 20 may share one ripple filtering unit 10, so as to achieve the purposes of saving cost and simplifying circuits while achieving the strobe-free dimming of the plurality of load units 20. It should be noted that, in the connection manner of fig. 5 and fig. 7 designed above, the principle of the ripple filtering unit 10 for eliminating stroboflash is the same as that of fig. 3, and is not described herein again.

In an alternative embodiment of the present embodiment, the dimming control unit 30 may include a PWM subunit 301, a reference modulation subunit 302, an integrating circuit 303, a power control subunit 304, a controllable switch transistor M2, and a resistor R2, where the controllable switch transistor M2 may also be a controllable switch transistor such as a MOS transistor or a triode, and the following connection modes are all exemplified by MOS transistors.

The PWM subunit 301, the reference modulation subunit 302, the integrating circuit 303, and the power control subunit 304 are sequentially connected in series, the power control subunit 304 is connected to the gate of the controllable switching tube M2, the source of the controllable switching tube M2 is connected to the integrating circuit 303 and grounded through the resistor R2, and when the connection manner between the ripple filtering unit 10 and the load unit 20 is as shown in fig. 3, as shown in fig. 8, the drain of the controllable switching tube M2 is connected to the source of the controllable switching tube M1; when the connection manner of the ripple filtering unit 10 and the load unit 20 is shown in fig. 5, the drain of the controllable switching tube M2 is connected to the negative electrode of the load unit 20 as shown in fig. 9; when the connection manner of the ripple filtering unit 10 and the load unit 20 is shown in fig. 7, as shown in fig. 10, the drain of each controllable switch M2 is connected to the negative electrode of each load unit 20.

When the circuit designed above is applied, the dimming control principle is as follows: the PWM subunit 301 receives an externally input PWM signal, and outputs a level signal corresponding to the PWM signal to the reference modulation subunit according to the PWM signal, the reference modulation subunit 302 determines a voltage value transmitted to the integrating circuit 303 according to the received level signal, the integrating circuit 303 outputs an integrated signal to the power control word unit 304 according to the voltage value received at the positive phase input terminal and the feedback voltage received at the negative phase input terminal, and the power control subunit 304 adjusts the voltage divided by the resistor R2 according to the received integrated signal, thereby implementing brightness adjustment of the load unit 20.

This application designs above-mentioned circuit and has following advantage for traditional circuit when realizing not having the stroboscopic and adjusting luminance: when the conventional circuit shown in fig. 1 is implemented without strobing, the charge loop occupies the major power consumption, and the power loop transistor of the main power loop must operate in the saturation region, i.e., the drain voltage (VDRN2) of the power loop transistor must be greater than the difference between the gate Voltage (VG) and the threshold Value (VTH), i.e., VG-VTH ≦ VDRN2, so that the minimum voltage at the DRN2 end of the main power loop must be maintained at a larger value, i.e., greater than VG-VTH, and the main power loop generates more loss; in addition, the capacitor C1 and the resistor R1 enable the voltage of the drain end of the controllable switch tube M2, namely the DRN end, to change along with the change of the bus voltage, and the voltage changes along with the increase and decrease of the bus voltage instead of being always maintained at a larger value, so that the loss of the dimming control unit is reduced, and the efficiency of the dimming control circuit is further improved; meanwhile, two diodes above the charging loop are eliminated, and therefore circuit cost is saved.

Further, as shown in fig. 8, fig. 9 or fig. 10, the PWM subunit 301 includes an operational amplifier L1, the reference modulation subunit 302 includes an inverter a1, an inverter a2, a controllable switch K1 and a controllable switch K2, the integrating circuit 303 includes an integrator G1 and a capacitor C3, and the power control subunit includes an operational amplifier L2.

The non-inverting input terminal of the operational amplifier L1 is used for receiving an externally input PWM signal, the inverting input terminal of the operational amplifier L1 is provided with a first reference voltage VREF1, and the output terminal of the operational amplifier L1 is connected to the input terminal of the inverter a 1.

The output end of the inverter a1 is connected with the input end of the inverter a2, the output end of the inverter a2 is connected with the control end of the controllable switch K1, the input end of the controllable switch K1 is connected with the second reference voltage VREF, the output end of the controllable switch K1 is connected with the positive input end of the integrator G1, the output end of the inverter a1 is further connected with the control end of the controllable switch K2, the input end of the controllable switch K2 is grounded, the output end of the controllable switch K2 is connected with the output end of the controllable switch K1, the negative input end of the integrator G1 is connected with the source of the controllable switch tube M2, the output end of the integrator G1 is connected with the positive input end of the operational amplifier L2, the output end of the integrator G1 is further grounded through the capacitor C3, the negative input end of the operational amplifier L2 is connected with the source of the controllable switch tube M2, and the output end of the operational amplifier L2 is connected with the gate of the controllable switch tube M2.

When the dimming control unit 30 designed as above is applied, the operational amplifier L1 outputs a high level signal or a low level signal according to the received PWM signal and the first reference voltage VREF1, and if the high level signal is a high level signal, the high level signal is transmitted to the inverter a1 for inversion to obtain a low level signal, the low level signal is transmitted to the controllable switch K2 to control the on/off of the controllable switch K2, and if the controllable switches K1 and K2 are both closed at a high level, the controllable switch K2 is opened at this time; the low level signal outputted from the inverter a1 is inverted again by the inverter a2 to obtain a high level signal, the high signal controls the controllable switch K1 to close, so that the second reference voltage VREF is communicated with the non-inverting input terminal of the integrator G1, the non-inverting input terminal of the integrator G1 inputs the average value (also a voltage value) of the second reference voltage VREF and the integrated duty cycle of the controllable switch K1, the inverting input end of the integrator G1 receives the integrated average value of the voltage fed back from the R2, the integrated average value of the second reference voltage VREF and the duty ratio of the controllable switch K1 and the integrated average value of the voltage fed back are integrated by the integrator G1 to output an integrated signal, the integrated signal is an average value obtained by integrating the second reference voltage VREF and the average value obtained by integrating the duty ratio of the controllable switch K1 and the average value obtained by integrating the feedback voltage.

The integrated signal is transmitted to the operational amplifier L2 through the non-inverting input terminal of the operational amplifier L2, since the operational amplifier L2 needs to maintain the voltage at its non-inverting input terminal and the voltage at its inverting input terminal the same, therefore, the inverting input terminal of the operational amplifier L2 will adjust the voltage value of the resistor R2 to the voltage value of the integrated signal inputted from the non-inverting input terminal thereof, so that the average value of the voltage value of the resistor R2 is equal to the average value of the second reference voltage VREF input at the non-inverting input terminal of the integrator G1 and the integrated duty ratio of the controllable switch K1, thereby changing the voltage across the resistor R2, since the average value of the current flowing through the resistor R2 is the same as the average value of the current flowing through the load cell 20, therefore, the switching of the controllable switches K1 and K2 and the voltage across the duty cycle adjusting resistor R2 can be regulated by the PWM signal, and then the voltage across the load unit 20 is adjusted to realize the brightness adjustment of the load unit 20.

In an alternative embodiment of this embodiment, as shown in fig. 11, the dimming control unit 30 further includes a bus sampling subunit 305 and a current compensation subunit 306, the bus sampling subunit 305 is connected to the current compensation subunit 306, and the current compensation subunit 306 is connected to the power control subunit 304.

When the circuit structure designed above is applied, the bus sampling subunit 305 samples a bus voltage signal and then transmits the bus voltage signal to the current compensation subunit 306, the current compensation subunit 306 generates a corresponding compensation signal according to the bus voltage signal and transmits the compensation signal to the power control subunit 304, and the power control subunit 304 compensates the current of the resistor R2 according to the compensation signal, so that the current of the resistor R2 is inversely proportional to the bus current, and the power consumption of the resistor R2 is further reduced.

It should be noted here that the integrating circuit 303 may be a circuit having digital integration, besides the integrator G1.

As a possible implementation, as shown in fig. 11, the bus sampling subunit 305 includes a resistor R3 and a resistor R4, the current compensation subunit 306 includes an operational amplifier L3, a MOS transistor M3, a MOS transistor M4, a MOS transistor M5, a resistor R5 and a resistor R6, the resistors R3 and R4 are connected in series and then connected to the source and ground of the controllable switch M1, the non-inverting input end of the operational amplifier L3 is connected between the resistors R3 and R4, the inverting input end of the operational amplifier L3 is grounded through the resistor R5, the output end of the operational amplifier L3 is connected with the gate of the MOS transistor M3, the source of the MOS transistor M3 is connected with the inverting input end of the operational amplifier L3, the drain of the MOS transistor M3 is connected with the drain of the MOS transistor M4, the drain of the MOS transistor M4 is also connected with the gate of the MOS transistor M4, the source of the MOS transistor M4 is connected with the source of the MOS transistor M5, the gate of the MOS transistor M4 is connected with the gate of the MOS transistor M5, and the drain of the MOS transistor M5 is connected with the power control subunit 304 and with the resistor R2 through the resistor R6.

In the circuit designed above, when applied, the resistor R3 and the resistor R4 sample the voltage information of the DRN terminal, and the voltage information of the DRN changes with the change of the bus voltage, so the voltage information of the DRN can represent the information of the bus voltage. It should be noted that the bus sampling subunit 305 in fig. 11 is connected to the voltage information of the DRN terminal, but in practice, the present invention is not limited to this, and any signal capable of expressing the bus information may be used, for example, the signal is directly connected to the bus to sample the bus voltage or the bus current, or, for example, is connected to the load unit to sample the voltage of the load unit.

The acquired voltage signal is transmitted to an operational amplifier L3, and a current corresponding to the voltage signal is output to a resistor R6 through the operational amplifier L3 and MOS transistors M3, M4 and M5, so that the current flowing through a resistor R6 and a bus signal change synchronously, and the current of the resistor R2 is reduced when the current of the resistor R6 is increased; when the current of the resistor R6 is reduced, the current of the resistor R2 is increased, so that the current of the resistor R2 is in inverse proportion to the bus signal, namely when the bus signal voltage is maximum, the current of the resistor R2 is minimum, the loss of the whole circuit system is further reduced, and the efficiency of the dimming control circuit is improved.

Second embodiment

The present application provides a dimming control system, as shown in fig. 12, the system includes a dimming control circuit 1 described in any one of the optional embodiments of the first embodiment, a rectifying unit 2, and a power supply 3, and the power supply 3 is connected to the dimming control circuit 1 through the rectifying unit 2.

The power supply 3 is an ac power supply, the rectifying unit 2 is a rectifying bridge, and the power supply 3 is connected to the dimming control circuit 1 through the rectifying bridge.

In the dimming control system designed as described above, since the dimming control system is designed based on the dimming control circuit 1 in the first embodiment, it can implement non-strobe dimming only by using one loop of the dimming control unit 30, and a charging loop in a conventional circuit is omitted, so that loss caused by the charging loop in the conventional circuit is eliminated, and many components in the charging loop are omitted, thereby reducing cost.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions when actually implemented, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.

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

Furthermore, the functional modules in the embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

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 above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dimming control circuit, comprising:

the ripple filtering unit (10) is connected with each load unit (20) in series, and the ripple filtering unit (10) is used for removing current ripples of each load unit (20);

the dimming control unit (30) is connected with one load unit (20) correspondingly, the number of the dimming control units (30) is the same as that of the load units (20), and the dimming control unit (30) is used for adjusting the voltage divided by the connected load units (20) according to the received PWM signal so as to adjust the brightness.

2. The dimming control circuit according to claim 1, wherein the load unit (20) and the dimming control unit (30) are both one, and the dimming control unit (30) is connected in series with the ripple filtering unit (10) and then connected in series with the load unit (20).

3. The dimming control circuit according to claim 2, wherein the ripple filtering unit (10) comprises a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1 and a capacitor C2, a control end of the controllable switch tube M1 is connected to a second end of the controllable switch tube M1 after being connected to a capacitor C1, a control end of the controllable switch tube M1 is connected to an anode of a zener diode Q1, a cathode of the zener diode Q1 is connected to a cathode of the load unit (20) after being connected to a resistor R1 in series, a first end of the controllable switch tube M1 is connected to a cathode of the load unit (20), an anode of the load unit (20) is connected to the second end of the controllable switch tube M1 through a capacitor C2, and the dimming control unit (30) is connected to the second end of the controllable switch tube M1.

4. The dimming control circuit according to claim 1, wherein the load unit (20) and the dimming control unit (30) are each one in number, and the load unit (20) is connected in series between the dimming control unit (30) and the ripple filtering unit (10).

5. The LED dimming control circuit according to claim 1, wherein the number of the load units (20) and the number of the dimming control units (30) are plural, and each dimming control unit (30) is connected in series with a corresponding load unit (20) and then connected in series with the ripple filtering unit (10).

6. The dimming control circuit according to claim 1, wherein each dimming control unit (30) comprises a PWM subunit (301), a reference modulation subunit (302), an integration circuit (303), a power control subunit (304), a controllable switch transistor M2 and a resistor R2, the PWM subunit (301), the reference modulation subunit (302), the integration circuit (303) and the power control subunit (304) are connected in series in sequence, the power control subunit (304) is connected with a control terminal of a controllable switch transistor M2, a second terminal of the controllable switch transistor M2 is connected with the integration circuit (303) and grounded through a resistor R2, and a first terminal of a controllable switch transistor M2 is connected with a corresponding load unit (20);

the PWM subunit (301) is used for receiving the PWM signal and outputting a level signal corresponding to the PWM signal to the reference modulation subunit (302) according to the PWM signal;

the reference modulation subunit (302) is used for determining a voltage value transmitted to the integrating circuit (303) according to the received level signal;

the integration circuit (303) is used for outputting an integration signal to the power control subunit (304) according to the voltage value received by the non-inverting input end and the feedback voltage received by the inverting input end;

the power control subunit (304) is used for adjusting the voltage divided by the resistor R2 according to the integral signal.

7. The dimming control circuit according to claim 6, wherein the PWM subunit (301) comprises an operational amplifier L1, the reference modulation subunit (302) comprises an inverter a1, an inverter a2, a controllable switch K1 and a controllable switch K2, the integration circuit (303) comprises an integrator G1 and a capacitor C3, the power control subunit (304) comprises an operational amplifier L2;

a non-inverting input terminal of the operational amplifier L1 is configured to receive the PWM signal, an inverting input terminal of the operational amplifier L1 is configured to receive a first reference voltage, and an output terminal of the operational amplifier L1 is connected to an input terminal of the inverter a 1;

the output end of the inverter A1 is connected with the input end of the inverter A2, the output end of the inverter A2 is connected with the control end of the controllable switch K1, the input end of the controllable switch K1 is connected with a second reference voltage, the output end of the controllable switch K1 is connected with the positive input end of the integrator G1, the output end of the inverter A1 is further connected with the control end of the controllable switch K2, the input end of the controllable switch K2 is grounded, and the output end of the controllable switch K2 is connected with the output end of the controllable switch K1;

the inverting input end of the integrator G1 is connected with the second end of the controllable switch tube M2, the output end of the integrator G1 is connected with the non-inverting input end of the operational amplifier L2, and the output end of the integrator G1 is also grounded through a capacitor C3;

the inverting input end of the operational amplifier L2 is connected to the second end of the controllable switch tube M2, and the output end of the operational amplifier L2 is connected to the control end of the controllable switch tube M2.

8. The dimming control circuit according to claim 6, wherein each dimming control unit (30) further comprises a bus sampling subunit (305) and a current compensation subunit (306), the bus sampling subunit (305) is connected with the current compensation subunit (306), and the current compensation subunit (306) is connected with the power control subunit (304);

the bus sampling subunit (305) is used for sampling a bus voltage signal and transmitting the bus voltage signal to the current compensation subunit (306);

the current compensation subunit (306) is used for generating a corresponding compensation signal according to the bus voltage signal and transmitting the compensation signal to the power control subunit (304);

the power control subunit (304) is further configured to compensate the current of the resistor R2 according to the compensation signal.

9. The dimming control circuit according to claim 8, wherein the bus sampling subunit (305) comprises a resistor R3 and a resistor R4, and the current compensation subunit (306) comprises an operational amplifier L3, a MOS transistor M3, a MOS transistor M4, a MOS transistor M5, a resistor R5, and a resistor R6;

the resistor R3 and the resistor R4 are connected in series and then are respectively connected with the second end and the ground end of the controllable switching tube M1, the non-inverting input end of the operational amplifier L3 is connected between the resistor R3 and the resistor R4, the inverting input end of the operational amplifier L3 is connected with the ground through the resistor R5, the output end of the operational amplifier L3 is connected with the gate of the MOS tube M3, the source of the MOS tube M3 is connected with the inverting input end of the operational amplifier L3, the drain of the MOS tube M3 is connected with the drain of the MOS tube M4, the drain of the MOS tube M4 is also connected with the gate of the MOS tube M4, the source of the MOS tube M4 is connected with the source of the MOS tube M5, the gate of the MOS tube M4 is connected with the gate of the MOS tube M5, and the drain of the MOS tube M5 is connected with the power control subunit (304) and is connected with the resistor R2 through the resistor R6.

10. A dimming control system, comprising: the dimming control circuit (1) as claimed in any of claims 1-9, the rectifying unit (2) and the power supply (3), the power supply (3) being connected to the dimming control circuit (1) through the rectifying unit (2).