CN219740663U

CN219740663U - LED drive circuit and drive chip with low load voltage

Info

Publication number: CN219740663U
Application number: CN202321022070.8U
Authority: CN
Inventors: 陈小平
Original assignee: Meixinsheng Technology Beijing Co ltd
Current assignee: Meixinsheng Technology Beijing Co ltd
Priority date: 2023-04-28
Filing date: 2023-04-28
Publication date: 2023-09-22
Anticipated expiration: 2033-04-28

Abstract

The application provides an LED driving circuit and a driving chip with low load voltage, which are characterized in that an input voltage detection module is used for detecting the input voltage, and when the input voltage is larger than the load voltage and smaller than a voltage set value, the input voltage detection module outputs a control signal to enable a second current source to work; when the input voltage is larger than the voltage set value, the input voltage detection module outputs a control signal to enable the first current source to work. The second current source is operated to enable an input current to flow through the LED load in the face of a low voltage input of 110/120 Vac. In the face of a high voltage input of 220/230Vac, the first stage is the operation of the second current source, the second stage is the operation of the first current source, and the third stage is the operation of the second current source, in one half-wave, the input current can flow through the LED load in each of the three stages. Therefore, the LED driving circuit of the present embodiment can be compatible with external input voltages of low voltage input and high voltage input.

Description

LED drive circuit and drive chip with low load voltage

Technical Field

The application relates to the technical field of LED driving, in particular to an LED driving circuit with low load voltage and a driving chip.

Background

The LED light source is a light source based on a light emitting diode and has the advantages of low-voltage power supply, low energy consumption, strong applicability, high stability, short response time, no pollution to the environment, multicolor light emission and the like. The existing LED driving technology adopts different schemes for the low voltage input facing 110/120Vac and the high voltage input facing 220/230Vac, that is, the existing LED driving technology cannot be compatible with the external input voltage of the low voltage input and the high voltage input.

Disclosure of Invention

The embodiment of the utility model aims to provide an LED driving circuit and a driving chip with low load voltage, which are used for solving the problem that the existing LED driving technology cannot be compatible with external input voltage of low-voltage input and high-voltage input.

The embodiment of the utility model provides an LED driving circuit with low load voltage, which comprises a first capacitor, a second capacitor, a first current source, a second current source and an input voltage detection module;

the positive end and the negative end of the first capacitor are respectively connected to the positive end and the negative end of the LED load in parallel, the negative end of the first capacitor is connected with the input end of the second current source, and the output end of the second current source is connected with the negative end of the power supply;

the positive end of the second capacitor is used for being connected with the output end of the LED load, the negative end of the second capacitor is connected with the input end of the first current source, and the output end of the first current source is used for being connected with the negative end of the power supply;

The input end of the input voltage detection module is used for being connected with the positive end of the power supply, the first output end of the input voltage detection module is connected with the controlled end of the first current source, and the second output end of the input voltage detection module is connected with the controlled end of the second current source;

the input voltage detection module is used for controlling the second current source to work and controlling the first current source to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than the voltage set value, controlling the first current source to work and controlling the second current source to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

The embodiment of the application provides an LED driving circuit with low load voltage, which comprises the following components: the device comprises a first diode, a second diode, a third diode, a first capacitor, a second capacitor, a first current source, a second current source and an input voltage detection module;

the input end of the first diode is used for being connected with the positive end of the power supply, the output end of the first diode is used for being connected with the positive end of the LED load, the input end of the third diode is used for being connected with the negative end of the LED load, the output end of the third diode is connected with the positive end of the second capacitor, the negative end of the second capacitor is connected with the input end of the first current source, and the output end of the first current source is used for being connected with the negative end of the power supply;

The output end of the third diode is also connected with the input end of the second diode, and the output end of the second diode is also used for being connected with the positive end of the LED load;

the input end of the first diode is also connected with the input end of the input voltage detection module, the first output end of the input voltage detection module is connected with the controlled end of the first current source, and the second output end of the input voltage detection module is connected with the controlled end of the second current source; the input voltage detection module is used for controlling the second current source to work and controlling the first current source to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than the voltage set value, the first current source is controlled to work, and the second current source is controlled to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

In the technical scheme, the input voltage detection module is used for detecting the input voltage, and when the input voltage is larger than the load voltage and smaller than the voltage set value, the input voltage detection module outputs a control signal to enable the second current source to work; when the input voltage is larger than the voltage set value, the input voltage detection module outputs a control signal to enable the first current source to work. The LED driving circuit operates at a low voltage input of 110/120Vac, and allows an input current to flow through the LED load. The LED driving circuit operates in a half wave with a second current source in the first stage and operates in the first current source in the third stage, and in the third stage, the LED driving circuit operates in the second current source in the third stage, and the LED driving circuit can flow an input current through the LED load in each of the three stages. Therefore, the LED driving circuit of the embodiment can be compatible with the external input voltage of the low voltage input of 110/120Vac and the high voltage input of 220/230 Vac.

In some alternative embodiments, further comprising: a first resistor, a second resistor, and a third resistor;

the output end of the first current source is connected with the first end of the first resistor, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is used for being connected with the negative end of the power supply;

the output end of the second current source is connected with the first end of the second resistor;

the input end of the first diode is also connected with the first end of the third resistor, and the second end of the third resistor is connected with the input end of the input voltage detection module.

In some alternative embodiments, further comprising: a third current source;

the input end of the third current source is connected with the second end of the third resistor, the output end of the third current source is connected with the second end of the second resistor, the reference voltage input end of the third current source is connected with the first end of the second resistor, and the controlled end of the third current source is connected with the third output end of the input voltage detection module.

In the above technical solution, since the LED driving circuit may be connected to the scr dimmer, a minimum holding current is required in order to enable the scr dimmer to work normally. Therefore, the third current source is provided in this embodiment, and the third current source is used to provide a smaller holding current for the scr dimmer.

In some alternative embodiments, further comprising: a rectifier bridge;

the positive input end of the rectifier bridge is used for connecting with the positive end of the alternating current power supply, and the negative input end of the rectifier bridge is used for connecting with the negative end of the alternating current voltage; the positive output end of the rectifier bridge is connected with the input end of the first diode, and the negative output end of the rectifier bridge is connected with the second end of the second resistor.

In the above technical solution, the input end of the rectifier bridge may be connected to the ac power source 110/120Vac with low voltage input, or may be connected to the ac power source 220/230Vac with high voltage input.

In some optional embodiments, the input voltage detection module is further configured to detect whether a positive input end of the rectifier bridge is connected to a triac dimmer, and control the third current source to operate when the rectifier bridge is connected to the triac dimmer; and when the rectifier bridge is not connected with the silicon controlled rectifier dimmer, the third current source is controlled to be closed.

According to the technical scheme, the input voltage detection module can judge whether the positive input end of the rectifier bridge is connected with the silicon controlled rectifier dimmer or not by detecting the waveform of the input voltage, and when the silicon controlled rectifier dimmer is connected between the rectifier bridge and the live wire, the third current source is controlled to work, and the maintenance current is provided for the silicon controlled rectifier dimmer, so that the silicon controlled rectifier dimmer can work normally. In addition, when the LED driving circuit is applied to the ac power supply 220/230Vac with high voltage input, the first stage is the operation of the second current source, the second stage is the operation of the first current source, and the third stage is the operation of the second current source, so that the input current can flow through the LED load in all three stages, that is, the time that the input current flows is longer, the adjusting angle of the scr dimmer is also larger, and the adjusting hand feeling of the user is improved.

When the thyristor dimmer is not connected between the rectifier bridge and the live wire, the third current source is controlled to be turned off without providing a maintaining current.

In some alternative embodiments, further comprising: a bandgap reference circuit and a voltage stabilizing circuit;

the output end of the first diode is also connected to a band gap reference circuit through a voltage stabilizing circuit.

The embodiment of the application provides an LED driving chip with low load voltage, which comprises the following components: the input voltage detection module, the first current source and the second current source; the LED driving chip is also provided with a first pin, a fourth pin, a fifth pin, a sixth pin and a seventh pin.

The first pin is connected with the input end of the input voltage detection module, the first output end of the input voltage detection module is connected with the controlled end of the first current source, the input end of the first current source is connected with the sixth pin, and the output end of the first current source is connected with the fifth pin;

the second output end of the input voltage detection module is connected with the controlled end of the second current source, the input end of the second current source is connected with the seventh pin, and the output end of the second current source is connected with the fourth pin;

the input voltage detection module is used for controlling the second current source to work and controlling the first current source to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than the voltage set value, the first current source is controlled to work, and the second current source is controlled to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

In the above technical scheme, the LED driving chip comprises an input voltage detection module, a first current source, a second current source and a plurality of pins. The first pin is used for being connected with the positive end of the power supply, the first pin is connected with the input end of the input voltage detection module, the input voltage detection module is used for detecting the input voltage, and when the input voltage is larger than the load voltage and smaller than a voltage set value, the input voltage detection module outputs a control signal to enable the second current source to work; when the input voltage is larger than the voltage set value, the input voltage detection module outputs a control signal to enable the first current source to work. The LED driver chip operates with the second current source facing a low voltage input of 110/120Vac, allowing an input current to flow through the LED load. The LED driving chip is operated by the second current source in a half-wave when facing the high-voltage input of 220/230Vac, the first stage is operated by the first current source, the third stage is operated by the second current source, and the input current can flow through the LED load in all three stages. Therefore, the LED driving chip of the embodiment can be compatible with the external input voltage of the low voltage input of 110/120Vac and the high voltage input of 220/230 Vac.

In some alternative embodiments, further comprising: a third current source, and a second pin and a third pin; the first pin is also connected with the input end of a third current source, the output end of the third current source is connected with the second pin, the reference voltage input end of the third current source is connected with the third pin, and the controlled end of the third current source is connected with the third output end of the input voltage detection module;

the input voltage detection module is also used for controlling the third current source to work when the rectifier bridge is connected with the silicon controlled rectifier dimmer; and when the rectifier bridge is not connected with the silicon controlled rectifier dimmer, the third current source is controlled to be closed.

In the technical scheme, a third current source is additionally arranged. The input voltage detection module can judge whether the positive input end of the rectifier bridge is connected with the silicon controlled rectifier dimmer or not by detecting the waveform of the input voltage, and when the silicon controlled rectifier dimmer is connected between the rectifier bridge and the live wire, the third current source is controlled to work, and the maintenance current is provided for the silicon controlled rectifier dimmer, so that the silicon controlled rectifier dimmer can work normally. When the thyristor dimmer is not connected between the rectifier bridge and the live wire, the third current source is controlled to be turned off without providing a maintaining current.

In some alternative embodiments, the method comprises: eighth pin, band gap reference circuit and voltage stabilizing circuit;

The bandgap reference circuit is connected to the eighth pin through the voltage stabilizing circuit.

In some alternative embodiments, the method comprises: a ninth pin, a second diode and a third diode;

the seventh pin is also connected with the input end of the third diode, the output end of the third diode is connected with the input end of the second diode, and the output end of the second diode is connected with the eighth pin;

the output end of the third diode is also connected with a ninth pin.

In the technical scheme, the diode in the LED circuit is integrated into the LED driving chip, and the integration level of the LED driving chip is higher, so that the volume of the whole circuit is reduced.

Drawings

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

Fig. 1 is a block diagram of an LED driving circuit according to an embodiment of the present application;

fig. 2 is a waveform diagram of an input current of the LED driving circuit of the first embodiment, which is not connected to the triac dimmer;

Fig. 3 is a waveform diagram of an input current of the LED driving circuit of the first embodiment connected with a triac dimmer;

FIG. 4 is a schematic diagram of an LED driving circuit according to another embodiment of the present application;

fig. 5 is a waveform diagram of an input current of the LED driving circuit of the second embodiment, which is not connected to the triac dimmer;

fig. 6 is a waveform diagram of an input current of the LED driving circuit of the second embodiment connected with a triac dimmer;

fig. 7 is a schematic diagram of a possible structure of an electronic device according to an embodiment of the present application;

fig. 8 is a block diagram of an LED driving circuit with low load voltage according to an embodiment of the present application;

fig. 9 is a waveform diagram of an input current when the LED driving circuit according to the embodiment of the present application is connected to a scr dimmer;

fig. 10 is a block diagram of another LED driving chip according to an embodiment of the present application;

fig. 11 is a waveform diagram of an input current when the LED driving circuit according to the embodiment of the present application is not connected to the scr dimmer and is input at low voltage.

Icon: 1-processor, 2-memory, 3-communication interface, 4-communication bus.

Detailed Description

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

Referring to fig. 1, fig. 1 is a block diagram of an LED driving circuit according to an embodiment of the present application, including: the device comprises a first diode D1, a first capacitor C1, a second current source IL, a third current source IBL, a second resistor R2, a third resistor R3 and an input voltage detection module.

The input end of the first diode D1 is used for being connected with the positive end of a power supply, the output end of the first diode D1 is connected with the first end of the first capacitor C1, the second end of the first capacitor C1 is connected with the input end of the second current source IL, the output end of the second current source IL is connected with the first end of the second resistor R2, and the second end of the second resistor R2 is used for being connected with the negative end of the power supply; the first and second ends of the first capacitor C1 are respectively connected in parallel to the positive and negative ends of the LED load. The input end of the first diode D1 is also connected with the input end of a third current source IBL through a third resistor R3, the output end of the third current source IBL is connected with the second end of a second resistor R2, and the reference voltage input end of the third current source IBL is connected with the first end of the second resistor R2.

The input end of the input voltage detection module is connected with the input end of the first diode D1 through a third resistor R3, the second output end of the input voltage detection module is connected with the controlled end of the second current source IL, and the third output end of the input voltage detection module is connected with the controlled end of the third current source IBL; the input voltage detection module is used for detecting input voltage and controlling the second current source IL to work when the input voltage is smaller than a voltage set value; judging whether the LED driving circuit is connected with a silicon controlled rectifier dimmer according to the input voltage, and controlling the third current source IBL to work in the period that the input voltage rises from 0 to the load voltage in each half wave when the LED driving circuit is connected with the silicon controlled rectifier dimmer; when the LED driving circuit is not connected with the silicon controlled rectifier dimmer, the third current source IBL is controlled to be closed.

In the embodiment of the application, when the LED driving circuit is connected with the silicon controlled rectifier dimmer, the input voltage waveform is presented as the front cut voltage waveform or the back cut voltage waveform, so that whether the LED driving circuit is connected with the silicon controlled rectifier dimmer can be judged by detecting the input voltage. The third current source IBL is set to provide a holding current for the triac dimmer, when the LED driving circuit is connected with the triac dimmer, the third current source IBL is controlled to operate during a period when an input voltage rises from 0 and then falls to a load voltage in each half-wave, in a stage when the input voltage falls to 0 from the load voltage, both the third current source IBL and the second current source IL do not operate, the input current falls to 0, heat generated by the holding current is reduced, and the input current in the stage is the same as the input current in the same stage when the triac dimmer is not connected, thereby improving power consistency of the LED driving circuit when the triac dimmer is connected with the triac dimmer. In the LED driving circuit of the present embodiment, the maintenance current flows through the LED load, and the heat generated by the maintenance current is transferred.

In some alternative embodiments, the input voltage detection module is further configured to:

When the LED driving circuit is connected with the silicon controlled rectifier dimmer, the third current source IBL is controlled to work before the input voltage drops to 0;

and/or when the LED driving circuit is not connected with the silicon controlled rectifier dimmer, controlling the second current source IL to output a constant current value IL; when the LED driving circuit is connected with a silicon controlled rectifier dimmer, the second current source IL is controlled to output a constant current value IL'; wherein, IL' is smaller than IL.

In the embodiment of the application, the input voltage detection module is controlled from the following two aspects to further improve the performance of the LED driving circuit:

in the first aspect, when the LED driving circuit is connected to the thyristor dimmer, the third current source IBL is operated during a period when the input voltage rises from 0 and then drops to the load voltage in each half-wave, further, the third current source IBL is controlled to operate for a short period of time before the input voltage drops to 0, and the third current source IBL is controlled to operate, so that the bias current is set for the thyristor dimmer in advance, so that the thyristor dimmer can be normally turned on in the next half-wave period, and the input current waveform is smoother and more complete.

In the second aspect, when the LED driving circuit is not connected to the triac dimmer, the second current source IL is controlled to output a constant current value as IL, and when the LED driving circuit is connected to the triac dimmer, the second current source IL is controlled to output an IL' with a smaller constant current value, so that the power consistency of the LED driving circuit when the triac dimmer is connected to the LED driving circuit and when the triac dimmer is not connected to the LED driving circuit is further improved.

The following describes the LED driving circuit of the present embodiment in detail with reference to an input current waveform diagram to which the triac dimmer is connected and an input current waveform diagram to which the triac dimmer is not connected:

referring to fig. 2, fig. 2 is a waveform diagram of an input current of the LED driving circuit of the first embodiment, which is not connected to the scr dimmer. Since the thyristor dimmer is not connected, the third current source IBL is always in an off state within a half-wave.

In the following embodiment, a load voltage of 135V, ac 230Vac, which is a load voltage having a voltage set value of 2 times, is taken as an example and explained in one half wave.

Before time t1, the input voltage is smaller than the load voltage, the input current is 0, and the second current source IL outputs 0.

At times t1 to t2, the input voltage is greater than the load voltage and less than the voltage set point. At the beginning of time t1, the second current source IL is operated for a period of time and, before time t2, the second current source IL is turned off, causing the input current to drop from a fixed value IL to 0.

At times t2 to t3, the input current is 0 and remains unchanged.

At times t3 to t4, the second current source IL is operated for a period of time. The second current source IL starts to operate at time t3, the input current starts to rise from 0 to a fixed value IL until time t4, the second current source IL is turned off and the input current drops to 0 because the input voltage is smaller than the load voltage.

After time t4, the input voltage is less than the load voltage and the input current is 0.

Referring to fig. 3, fig. 3 is a waveform diagram of an input current of the LED driving circuit of the first embodiment connected with a scr dimmer.

At times t1 to t2, the input voltage is greater than the load voltage and less than the voltage set point. At the beginning of time t1, the second current source IL is operated for a period of time and, before time t2, the second current source IL is turned off, causing the input current to drop from a fixed value IL to IBL.

At times t2 to t3, the input current is IBL and remains unchanged.

At times t3 to t4, the second current source IL is operated for a period of time. The second current source IL starts to operate at time t3, the input current starts to rise from IBL to a fixed value IL until time t4, the second current source IL is turned off because the input voltage is smaller than the load voltage, at this time, the third current source IBL is controlled to be turned off, and the input current drops to 0.

After the time t4, before the input voltage drops to 0, the third current source IBL is controlled to operate, and the third current source IBL outputs current to ensure that the scr dimmer can be normally turned on in the next half-wave period.

Referring to fig. 4, fig. 4 is a block diagram of an LED driving circuit according to another embodiment of the present application. The LED driving circuit in this embodiment further includes: a first current source IH, a first resistor R1 and a second capacitor C2.

The first end of the second capacitor C2 is used for being connected with the negative end of the LED load, the second end of the second capacitor C2 is connected with the input end of the first current source IH, and the output end of the first current source IH is connected with the first end of the second resistor R2 through the first resistor R1.

The input voltage detection module is also used for: when the input voltage is smaller than the voltage set value, controlling the second current source IL to work and controlling the first current source IH to be closed; when the input voltage is larger than the voltage set value, the first current source IH is controlled to work, and the second current source IL is controlled to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

In the embodiment of the application, an input voltage detection module is utilized to detect the input voltage, and when the input voltage is larger than the load voltage and smaller than a voltage set value, the input voltage detection module outputs a control signal to enable the second current source IL to work; when the input voltage is larger than the voltage set value, the input voltage detection module outputs a control signal to enable the first current source IH to work. The LED driving circuit operates the second current source IL at a low voltage input of 110/120Vac, and allows an input current to flow through the LED load. The LED driving circuit is operated by the second current source IL during one half-wave, the first current source IH during the second phase, and the second current source IL during the third phase, in response to the high voltage input of 220/230Vac, to enable the input current to flow through the LED load during each of the three phases. Therefore, the LED driving circuit of the embodiment can be compatible with the external input voltage of the low voltage input of 110/120Vac and the high voltage input of 220/230 Vac.

The third current source IBL outputs a constant current ibl=vbl/R2, where VBL is the voltage of the second resistor R2.

In some alternative embodiments, further comprising: a rectifier bridge BRIG;

the positive input end of the rectifier bridge BRIG is used for being connected with the positive end of the alternating current power supply, and the negative input end of the rectifier bridge BRIG is used for being connected with the negative end of the alternating current voltage; the positive output end of the rectifier bridge BRIG is connected with the input end of the first diode D1, and the negative output end of the rectifier bridge BRIG is connected with the second end of the second resistor R2.

In the embodiment of the application, the input end of the rectifier bridge BRIG can be connected with the alternating current power supply 110/120Vac of low voltage input or the alternating current power supply 220/230Vac of high voltage input, and the silicon controlled rectifier dimmer is arranged between the rectifier bridge BRIG and the alternating current power supply.

the output end of the first diode D1 is also connected to the bandgap reference circuit through the voltage stabilizing circuit.

In some alternative embodiments, the LED driving circuit further includes a second diode D2 and a third diode D3, the output terminal of the second diode D2 is connected to the positive terminal of the LED load, the input terminal of the second diode D2 is connected to the output terminal of the third diode D3, and the input terminal of the third diode D3 is connected to the negative terminal of the LED load.

referring to fig. 5, fig. 5 is a waveform diagram of an input current of the LED driving circuit of the second embodiment, which is not connected to the scr dimmer. Since the thyristor dimmer is not connected, the third current source IBL is always in an off state within a half-wave.

Before time t1, the input voltage is lower than the load voltage and the input current is 0.

At times t1 to t2, the input voltage is greater than the load voltage and less than the voltage set point. At the beginning of time t1, the first current source IH is turned off, the second current source IL is operated for a period of time, and the second current source IL is turned off before time t2, so that the input current is reduced to 0 from a fixed value IL for a period of time; the input current falling phase and the input current maintaining phase are set for the purpose of reducing power and improving the efficiency of the circuit. During the falling process of the input current, the falling slope is related to the efficiency, the faster the falling process, the higher the efficiency, the value of the slope is usually set according to the use situation, and if the input current falls too fast, the current mutation problem is caused.

At times t2 to t3, the input voltage is greater than the voltage set point, the first current source IH is operated, and the second current source IL is turned off. Starting at time t2, the input current rises to a fixed value IH, after which the input current remains unchanged.

At time t3 to t4, the input voltage is smaller than the voltage set point and larger than the load voltage, the first current source IH is turned off, and the second current source IL operates for a period of time. The first current source IH is turned off beginning at time t3, the input current drops to 0 and is maintained for a period of time, after which the second current source IL is operated, the input current rises from 0 to a fixed value IL, and the second current source IL is turned off until time t 4.

Referring to fig. 6, fig. 6 is a waveform diagram of an input current of the LED driving circuit of the second embodiment connected with a scr dimmer.

Before time t1, the third current source IBLIBL starts to operate, the input current rises from 0 to the sustain current IBL, and then the input current remains unchanged.

At times t1 to t2, the input voltage is greater than the load voltage and less than the voltage set point. At the beginning of time t1, the first current source IH is turned off, the second current source IL is operated for a period of time, and the second current source IL is turned off before time t2, so that the input current is reduced from a fixed value IL to IBL for a period of time; the input current falling stage and the stage in which the input current maintains IBL are set in order to reduce power and improve the efficiency of the circuit. During the falling process of the input current, the falling slope is related to the efficiency, the faster the falling process, the higher the efficiency, the value of the slope is usually set according to the use situation, and if the input current falls too fast, the current mutation problem is caused.

At time t3 to t4, the input voltage is smaller than the voltage set point and larger than the load voltage, the first current source IH is turned off, and the second current source IL operates for a period of time. The first current source IH is turned off beginning at time t3, the input current drops to IBL and is maintained for a period of time, after which the second current source IL is operated, the input current rises from IBL to a fixed value IL, until time t4, the second current source IL is turned off.

After time t4, the input voltage is smaller than the load voltage, the second current source IL outputs 0, and at this time, the third current source IBL is turned off, and the input current is 0. And before the input voltage is reduced to 0, the third current source IBL is controlled to work, and the third current source IBL outputs current to ensure that the thyristor dimmer can be normally conducted in the next half-wave period.

Referring to fig. 8, fig. 8 is a block diagram of an LED driving circuit with low load voltage according to an embodiment of the present application, which specifically includes: the first diode D1, the second diode D2, the third diode D3, the first capacitor, the second capacitor, the first current source IH, the second current source IL and the input voltage detection module.

The input end of the first diode D1 is used for being connected with the positive end of a power supply, the output end of the first diode D1 is used for being connected with the positive end of an LED load, the input end of the third diode D3 is used for being connected with the negative end of the LED load, the output end of the third diode D3 is connected with the positive end of the second capacitor, the negative end of the second capacitor is connected with the input end of the first current source IH, and the output end of the first current source IH is used for being connected with the negative end of the power supply; the output end of the third diode D3 is also connected with the input end of the second diode D2, and the output end of the second diode D2 is also used for being connected with the positive end of the LED load; the positive end and the negative end of the first capacitor are respectively connected to the positive end and the negative end of the LED load in parallel, the negative end of the first capacitor is connected with the input end of the second current source IL, and the output end of the second current source IL is connected with the negative end of the power supply; the input end of the first diode D1 is also connected with the input end of the input voltage detection module, the first output end of the input voltage detection module is connected with the controlled end of the first current source IH, and the second output end of the input voltage detection module is connected with the controlled end of the second current source IL; the input voltage detection module is used for controlling the second current source IL to work and controlling the first current source IH to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than the voltage set value, the first current source IH is controlled to work, and the second current source IL is controlled to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

In some alternative embodiments, further comprising: a first resistor R1, a second resistor R2 and a third resistor R3. The output end of the first current source IH is connected with the first end of the first resistor R1, the second end of the first resistor R1 is connected with the first end of the second resistor R2, and the second end of the second resistor R2 is used for being connected with the negative end of the power supply; the output end of the second current source IL is connected with the first end of the second resistor R2; the input end of the first diode D1 is also connected with the first end of the third resistor R3, and the second end of the third resistor R3 is connected with the input end of the input voltage detection module.

In some alternative embodiments, further comprising: and a third current source IBL. The input end of the third current source IBL is connected to the second end of the third resistor R3, the output end of the third current source IBL is connected to the second end of the second resistor R2, the reference voltage input end of the third current source IBL is connected to the first end of the second resistor R2, and the controlled end of the third current source IBL is connected to the third output end of the input voltage detection module.

In the embodiment of the application, since the LED driving circuit may be connected to the scr dimmer, a minimum holding current is required in order to enable the scr dimmer to work normally. Therefore, the third current source IBL is provided in this embodiment, and the third current source IBL is used to provide a smaller holding current for the triac dimmer.

In some alternative embodiments, further comprising: and a rectifier bridge BRIG. The positive input end of the rectifier bridge BRIG is used for being connected with the positive end of the alternating current power supply, and the negative input end of the rectifier bridge BRIG is used for being connected with the negative end of the alternating current voltage; the positive output end of the rectifier bridge BRIG is connected with the input end of the first diode D1, and the negative output end of the rectifier bridge BRIG is connected with the second end of the second resistor R2.

In the embodiment of the application, the input end of the rectifier bridge BRIG can be connected with the alternating current power supply 110/120Vac of low-voltage input or the alternating current power supply 220/230Vac of high-voltage input.

In some alternative embodiments, further comprising: the output end of the first diode D1 is also connected to the band gap reference circuit through the voltage stabilizing circuit.

In some optional embodiments, the input voltage detection module is further configured to detect whether a triac dimmer is connected to the positive input terminal of the rectifier bridge BRIG, and control the third current source IBL to operate when the triac dimmer is connected to the rectifier bridge BRIG; when the rectifier bridge BRIG is not connected to the triac dimmer, the third current source IBL is controlled to be turned off.

In the embodiment of the application, the input voltage detection module can judge whether the positive input end of the rectifier bridge BRIG is connected with the silicon controlled rectifier dimmer or not by detecting the waveform of the input voltage:

in the first case, when the scr dimmer is not connected between the bridge BRIG and the hot line, the third current source IBL is controlled to be turned off without providing the sustain current, and the waveform is shown in fig. 5.

In the second situation, when the thyristor dimmer is connected between the rectifier bridge BRIG and the live wire, the third current source IBL is controlled to work, and a maintaining current is provided for the thyristor dimmer, so that the thyristor dimmer can work normally. In addition, when the LED driving circuit is applied to the ac power supply 220/230Vac with high voltage input, the first stage is the operation of the second current source IL, the second stage is the operation of the first current source IH, and the third stage is the operation of the second current source IL, and in all three stages, the input current can flow through the LED load, that is, the time that the input current flows is longer, the adjusting angle of the scr dimmer is also larger, and the adjusting hand feel of the user is improved.

Referring to fig. 11, fig. 11 is a waveform diagram of an input current when the LED driving circuit provided by the embodiment of the application is not connected to the scr dimmer and is input at low voltage. In this embodiment, the ac 110Vac is input at a load voltage of 135V, and is illustrated as an example in one half wave.

Before time t1, the input voltage is smaller than the load voltage, the input current is 0, until time t1, the input voltage rises to the load voltage, and the input current starts to rise to a fixed value IL;

at time t1 to time t2, the input voltage is greater than the load voltage, the input current remains constant at a fixed value IL until time t2, the input voltage drops to the load voltage, and the input current drops to 0.

Referring to fig. 9, fig. 9 is a waveform diagram of an input current when the LED driving circuit according to the embodiment of the application is connected to a scr dimmer.

In this embodiment, the load voltage 135V, the input ac 230Vac, is a load voltage with a voltage set value of 2 times, and is illustrated in one half wave.

Before time t1, the third current source IBL starts to operate, the input current rises from 0 to the sustain current IBL, and then the input current remains unchanged.

After time t4, the input voltage is less than the load voltage and the input current drops from IBL to 0.

The LED driving chip shown in fig. 8, a low-load voltage LED driving chip, specifically includes: an input voltage detection module, a first current source IH and a second current source IL. The LED driving chip is provided with a plurality of pins.

The first pin A1 is connected with the input end of the input voltage detection module, the first output end of the input voltage detection module is connected with the controlled end of the first current source IH, the input end of the first current source IH is connected with the sixth pin A6, and the output end of the first current source IH is connected with the fifth pin A5; the second output end of the input voltage detection module is connected with the controlled end of the second current source IL, the input end of the second current source IL is connected with the seventh pin A7, and the output end of the second current source IL is connected with the fourth pin A4; the input voltage detection module is used for controlling the second current source IL to work and controlling the first current source IH to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than the voltage set value, the first current source IH is controlled to work, and the second current source IL is controlled to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

In the embodiment of the application, the LED driving chip comprises an input voltage detection module, a first current source IH, a second current source IL and a plurality of pins. The first pin A1 is used for being connected with the positive end of the power supply, the first pin A1 is connected with the input end of the input voltage detection module, the input voltage detection module is used for detecting the input voltage, and when the input voltage is larger than the load voltage and smaller than a voltage set value, the input voltage detection module outputs a control signal to enable the second current source IL to work; when the input voltage is larger than the voltage set value, the input voltage detection module outputs a control signal to enable the first current source IH to work. The LED driving chip operates at a low voltage input of 110/120Vac, and the second current source IL may cause an input current to flow through the LED load. The LED driving chip is operated by the second current source IL in a half-wave when facing the high-voltage input of 220/230Vac, the first stage is operated by the first current source IH, and the third stage is operated by the second current source IL, and the input current can flow through the LED load in all three stages. Therefore, the LED driving chip of the embodiment can be compatible with the external input voltage of the low voltage input of 110/120Vac and the high voltage input of 220/230 Vac.

In some alternative embodiments, further comprising: and a third current source IBL.

The first pin A1 is also connected with the input end of a third current source IBL, the output end of the third current source IBL is connected with the second pin A2, the reference voltage input end of the third current source IBL is connected with the third pin A3, and the controlled end of the third current source IBL is connected with the third output end of the input voltage detection module; the input voltage detection module is further used for controlling the third current source IBL to work when the rectifier bridge BRIG is connected with the silicon controlled rectifier dimmer; when the rectifier bridge BRIG is not connected to the triac dimmer, the third current source IBL is controlled to be turned off.

In the embodiment of the application, a third current source IBL is additionally arranged. The input voltage detection module can judge whether the positive input end of the rectifier bridge BRIG is connected with the silicon controlled rectifier dimmer or not by detecting the waveform of the input voltage, and when the silicon controlled rectifier dimmer is connected between the rectifier bridge BRIG and the live wire, the third current source IBL is controlled to work so as to provide maintenance current for the silicon controlled rectifier dimmer, so that the silicon controlled rectifier dimmer can work normally. When the thyristor dimmer is not connected between the rectifier bridge BRIG and the live wire, the third current source IBL is controlled to be turned off without providing a sustain current.

In some alternative embodiments, the method comprises: a bandgap reference circuit and a voltage stabilizing circuit; the bandgap reference circuit is connected to the eighth pin A8 through a voltage stabilizing circuit.

Referring to fig. 10, fig. 10 is a block diagram of another LED driving chip according to an embodiment of the present application. Specifically, the difference from the LED driving chip is that: the LED driving chip of the present embodiment further integrates a second diode D2 and a third diode D3. The seventh pin A7 is also connected with the input end of a third diode D3, the output end of the third diode D3 is connected with the input end of a second diode D2, and the output end of the second diode D2 is connected with an eighth pin A8; the output end of the third diode D3 is further connected to the ninth pin A9. In the embodiment of the application, the diode in the LED circuit is integrated into the LED driving chip, and the integration level of the LED driving chip is higher, so that the volume of the whole circuit is reduced.

The embodiment of the application provides a control method of an LED driving circuit, which comprises the following steps: and detecting the input voltage, and controlling the second current source IL to work when the input voltage is smaller than the voltage set value.

Judging whether the LED driving circuit is connected with a silicon controlled rectifier dimmer according to the input voltage, and controlling the third current source IBL to work in the period that the input voltage rises from 0 to the load voltage in each half wave when the LED driving circuit is connected with the silicon controlled rectifier dimmer; when the LED driving circuit is not connected with the silicon controlled rectifier dimmer, the third current source IBL is controlled to be closed.

In the embodiment of the application, a third current source IBL is provided in the LED driving circuit to provide the holding current for the scr dimmer. When the LED driving circuit is detected to be connected with the controllable silicon light modulator, the third current source IBL is controlled to work in the period that the input voltage is increased from 0 and then reduced to the load voltage in each half wave, and in the period that the input voltage is reduced to 0 from the load voltage, the third current source IBL and the second current source IL are not operated, the input current is reduced to 0, the heat generated by the maintaining current is reduced, the input current in the period is the same as the input current in the same period when the controllable silicon light modulator is not connected, and therefore the power consistency of the LED driving circuit when the controllable silicon light modulator is connected and the controllable silicon light modulator is not connected is improved.

In some alternative embodiments, the method further comprises: when the LED driving circuit is connected with the silicon controlled rectifier dimmer, the third current source IBL is controlled to work before the input voltage drops to 0.

In some alternative embodiments, the method further comprises: when the input voltage is smaller than the voltage set value, controlling the second current source IL to work and controlling the first current source IH to be closed; when the input voltage is larger than the voltage set value, the first current source IH is controlled to work, and the second current source IL is controlled to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

Fig. 7 shows a possible structure of the electronic device provided by the embodiment of the application. Referring to fig. 7, the electronic device includes: processor 1, memory 2, and communication interface 3, which are interconnected and communicate with each other by a communication bus 4 and/or other forms of connection mechanisms (not shown).

The Memory 2 includes one or more (Only one is shown in the figure), which may be, but is not limited to, a random access Memory (Random Access Memory, RAM for short), a Read Only Memory (ROM for short), a programmable Read Only Memory (Programmable Read-Only Memory, PROM for short), an erasable programmable Read Only Memory (Erasable Programmable Read-Only Memory, EPROM for short), an electrically erasable programmable Read Only Memory (Electric Erasable Programmable Read-Only Memory, EEPROM for short), and the like. The processor 1 and possibly other components may access the memory 2, read and/or write data therein.

The processor 1 comprises one or more (only one shown in the figure), which may be an integrated circuit chip with signal processing capabilities. The processor 1 may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a micro control unit (Micro Controller Unit, MCU), a network processor (Network Processor, NP), or other conventional processor; but may also be a special purpose processor including a Neural Network Processor (NPU), a graphics processor (Graphics Processing Unit GPU), a digital signal processor (Digital Signal Processor DSP), an application specific integrated circuit (Application Specific Integrated Circuits ASIC), a field programmable gate array (Field Programmable Gate Array FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components. Also, when the processor 1 is plural, some of them may be general-purpose processors, and the other may be special-purpose processors.

The communication interface 3 comprises one or more (only one is shown) and may be used for direct or indirect communication with other devices for data interaction. The communication interface 3 may comprise an interface for wired and/or wireless communication.

One or more computer program instructions may be stored in the memory 2, which may be read and executed by the processor 1 to implement the methods provided by embodiments of the present application.

It will be appreciated that the configuration shown in fig. 7 is merely illustrative, and that the electronic device may also include more or fewer components than shown in fig. 7, or have a different configuration than shown in fig. 7. The components shown in fig. 7 may be implemented in hardware, software, or a combination thereof. The electronic device may be a physical device such as a PC, a notebook, a tablet, a cell phone, a server, an embedded device, etc., or may be a virtual device such as a virtual machine, a virtualized container, etc. The electronic device is not limited to a single device, and may be a combination of a plurality of devices or a cluster of a large number of devices.

The embodiment of the application also provides a computer readable storage medium, and the computer readable storage medium stores computer program instructions, which when read and run by a processor of a computer, execute the method provided by the embodiment of the application. For example, the computer readable storage medium may be implemented as the memory 2 in the electronic device of fig. 7.

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

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

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

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

The 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 variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. The LED driving circuit with low load voltage is characterized by comprising a first capacitor, a second capacitor, a first current source, a second current source and an input voltage detection module;

the positive end and the negative end of the first capacitor are respectively connected in parallel to the positive end and the negative end of the LED load, the negative end of the first capacitor is connected with the input end of the second current source, and the output end of the second current source is connected with the negative end of the power supply; the positive end of the second capacitor is used for being connected with the output end of the LED load, the negative end of the second capacitor is connected with the input end of the first current source, and the output end of the first current source is used for being connected with the negative end of the power supply;

The input end of the input voltage detection module is used for being connected with the positive end of a power supply, the first output end of the input voltage detection module is connected with the controlled end of the first current source, and the second output end of the input voltage detection module is connected with the controlled end of the second current source; the input voltage detection module is used for controlling the second current source to work and controlling the first current source to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than a voltage set value, controlling the first current source to work and controlling the second current source to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

2. The circuit of claim 1, further comprising: a first diode, a second diode, a third diode, a first resistor, a second resistor, and a third resistor;

the input end of the first diode is used for being connected with the positive end of the power supply, the output end of the first diode is used for being connected with the positive end of the LED load, the input end of the third diode is used for being connected with the negative end of the LED load, and the output end of the third diode is connected with the positive end of the second capacitor;

3. The circuit of claim 2, further comprising: a third current source;

4. The circuit of claim 3, further comprising: a rectifier bridge;

The positive input end of the rectifier bridge is used for being connected with the positive end of an alternating current power supply, and the negative input end of the rectifier bridge is used for being connected with the negative end of alternating current voltage; the positive output end of the rectifier bridge is connected with the input end of the first diode, and the negative output end of the rectifier bridge is connected with the second end of the second resistor.

5. The circuit of claim 4, wherein the input voltage detection module is further configured to detect whether a triac dimmer is connected to a positive input of the rectifier bridge, and to control the third current source to operate if it is detected that the rectifier bridge is connected to a triac dimmer; and controlling the third current source to be closed under the condition that the rectifier bridge is not connected with the silicon controlled rectifier dimmer.

6. The circuit of claim 2, further comprising: a bandgap reference circuit and a voltage stabilizing circuit;

the output end of the first diode is also connected to the band gap reference circuit through the voltage stabilizing circuit.

7. A low load voltage LED driver chip, comprising: the input voltage detection module comprises a first current source, a second current source, a first pin, a fourth pin, a fifth pin, a sixth pin and a seventh pin;

the input voltage detection module is used for controlling the second current source to work and controlling the first current source to be closed when the input voltage is smaller than a voltage set value; when the input voltage is larger than a voltage set value, controlling the first current source to work and controlling the second current source to be closed; wherein the voltage set point is greater than the load voltage, which is less than the maximum voltage of the low voltage input of 110/120 Vac.

8. The chip of claim 7, further comprising: a second pin, a third pin, and a third current source;

the first pin is also connected with the input end of the third current source, the output end of the third current source is connected with the second pin, the reference voltage input end of the third current source is connected with the third pin, and the controlled end of the third current source is connected with the third output end of the input voltage detection module;

The input voltage detection module is also used for controlling the third current source to work when the rectifier bridge is connected with the silicon controlled rectifier dimmer; and when the rectifier bridge is not connected with the silicon controlled rectifier dimmer, controlling the third current source to be closed.

9. The chip of claim 7, comprising: eighth pin, band gap reference circuit and voltage stabilizing circuit;

10. The chip of claim 7, comprising: the second diode, the third diode and the ninth pin;

and the output end of the third diode is also connected with a ninth pin.