CN110582143A - LED dimming circuit, dimming method and LED control circuit - Google Patents
LED dimming circuit, dimming method and LED control circuit Download PDFInfo
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- CN110582143A CN110582143A CN201910952283.2A CN201910952283A CN110582143A CN 110582143 A CN110582143 A CN 110582143A CN 201910952283 A CN201910952283 A CN 201910952283A CN 110582143 A CN110582143 A CN 110582143A
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Abstract
the invention provides an LED dimming circuit, a dimming method and an LED control circuit, wherein the LED dimming circuit controls load current according to a dimming signal, and the dimming signal is an analog signal or a PWM signal; in a half power frequency period, the load current waveform is concave, the dimming signal adjusts the concave coefficient of the load current waveform, and the concave coefficient represents the concave degree of the load current waveform. The invention can improve the stability of the load current when the load current is smaller.
Description
Technical Field
The invention relates to the field of power electronics, in particular to an LED dimming circuit, a dimming method and an LED control circuit.
Background
In the prior art, in order to improve the working efficiency of an LED load, current compensation is often performed on the LED load current, so that the waveform of the LED load current is concave (in a half power frequency cycle, the current is large at two sides and small at the middle), and the output power of the LED load is kept as constant as possible. In the dimming application, as shown in fig. 1, when the dimming signal is small, that is, the LED load current is small, due to the existence of current compensation, the two ends of the LED load current are very high due to the internal constant current mechanism, so that the LED load current is unstable, and the LED is easily damaged.
Disclosure of Invention
the invention aims to provide an LED dimming circuit, a dimming method and an LED control circuit, which are used for solving the problem of unstable LED load current in the prior art.
In order to achieve the above object, the present invention provides an LED dimming circuit, wherein an ac input power source is rectified by a rectifier circuit to obtain an input voltage, the input voltage supplies power to an LED load, the LED dimming circuit controls a load current according to a dimming signal, and the dimming signal is an analog signal or a PWM signal; in a half power frequency period, the load current waveform is concave, the dimming signal adjusts the concave coefficient of the load current waveform, and the concave coefficient represents the concave degree of the load current waveform.
Optionally, when the dimming signal is greater than or equal to the first threshold, the dip coefficient is a first fixed value;
When the dimming signal is greater than a second threshold and smaller than a first threshold, the dip coefficient is smaller than a first fixed value and larger than a second fixed value, and the smaller the dimming signal is, the smaller the dip coefficient is;
When the dimming signal is less than or equal to the second threshold, the dip coefficient is a second fixed value.
Optionally, the LED dimming circuit includes a compensation circuit, and obtains a reference signal or a feedback signal representing a load current according to the dimming signal, the compensation circuit receives the reference signal and the feedback signal, the compensation circuit compensates an error between the reference signal and the feedback signal, outputs a compensation voltage, and the compensation voltage controls a load average current.
Optionally, the LED dimming circuit further includes a dip coefficient adjusting circuit, a dip compensation circuit, and a first control circuit, where the dip coefficient adjusting circuit receives the dimming signal and outputs the dip coefficient; the sinking compensation circuit receives the sinking coefficient and a sampling signal representing input voltage and outputs a sinking control signal; the first control circuit receives the compensation voltage and the sinking control signal and outputs a first control signal, and the first control signal controls the load current.
The invention also provides an LED dimming method, wherein an alternating current input power supply is rectified by a rectifying circuit to obtain an input voltage, the input voltage supplies power to an LED load, the LED dimming circuit controls a load current according to the dimming signal, and the dimming signal is an analog signal or a PWM signal; in a half power frequency period, the load current waveform is concave, the concave coefficient of the load current waveform is adjusted according to the dimming signal, and the concave coefficient represents the concave degree of the load current waveform.
Optionally, when the dimming signal is greater than or equal to the first threshold, the dip coefficient is a first fixed value;
When the dimming signal is greater than a second threshold and smaller than a first threshold, the dip coefficient is smaller than a first fixed value and larger than a second fixed value, and the smaller the dimming signal is, the smaller the dip coefficient is;
When the dimming signal is less than or equal to the second threshold, the dip coefficient is a second fixed value.
Optionally, a reference signal or a feedback signal representing the load current is obtained according to the dimming signal, an error between the reference signal and the feedback signal is compensated to obtain a compensation voltage, and the compensation voltage controls the load average current.
the invention also provides an LED control circuit which comprises any one of the LED dimming circuits
Compared with the prior art, the invention has the following advantages: controlling load current according to the dimming signal, wherein the dimming signal is an analog signal or a PWM signal; in a half power frequency period, the load current waveform is concave, the concave coefficient of the load current waveform is adjusted according to the dimming signal, and the concave coefficient represents the concave degree of the load current waveform. The invention can improve the stability of the load current when the load current is smaller.
Drawings
FIG. 1 is a schematic diagram of a prior art load current waveform;
FIG. 2 is a schematic view of a load current waveform according to the present invention;
FIG. 3 is a schematic diagram of a dimming circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a second embodiment of the dimming circuit of the present invention;
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.
In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale for the purpose of facilitating and clearly explaining the embodiments of the present invention.
As shown in fig. 2, which illustrates a load current waveform diagram of the present invention, the ac input power is rectified to obtain the input voltage VIN, and when the input voltage VIN is greater than the LED turn-on threshold VF, the LED is turned on. When the dimming signal is greater than a first threshold value DM1, sinking the load current iLED (in a half power frequency period, the load current is large at two sides and small at the middle), wherein the sinking coefficient is a first fixed value; when the dimming signal is greater than the second threshold DM2 and less than or equal to the first threshold DM1, the load current iLED sinks downward, the sinking coefficient is less than the first fixed value and greater than the second fixed value, and the smaller the dimming signal is, the smaller the sinking coefficient is; when the dimming signal is less than or equal to the second threshold DM2, the load current iLED sinks, and the sinking coefficient is a second fixed value. The sinking coefficient represents the sinking degree of the waveform of the load current iLED, the sinking degree refers to the difference value between the sinking valley value of the load current and the average current of the load current, and the larger the sinking degree is, the larger the difference value is.
As shown in fig. 3, a schematic diagram of an embodiment of the dimming circuit of the present invention is illustrated, which includes a reference generating circuit U101, a compensating circuit U102, a feedback circuit U103, a sag factor adjusting circuit U104, a sag compensating circuit U105, a first control circuit U106, and a driving circuit U107. The reference signal generating circuit U101 receives the dimming signal and outputs a reference signal VREF; one end of the feedback circuit U103 is connected with a driving circuit U107 to output a sampling signal VCS representing output current; the compensation circuit U102 receives the reference signal VREF and the sampling signal VCS, compensates an error between the reference signal VREF and the sampling signal VCS, and outputs a compensation signal COMP. The sinking coefficient adjusting circuit U104 receives the dimming signal and outputs a sinking coefficient K; the sinking compensation circuit U105 receives the adjustment coefficient K and the input voltage VIN and outputs a sinking control signal VC 1; the first control circuit U106 receives the compensation signal COMP and the deboss control signal VC1, and outputs a first control signal VC2, typically VC2 ═ COMP-K × VIN, and the first control signal VC2 controls the load current. In addition, when the dimming signal is greater than or equal to the first threshold, the dip coefficient K is a first fixed value; when the dimming signal is greater than a second threshold and smaller than a first threshold, the dip coefficient K is smaller than a first fixed value and larger than a second fixed value, and the smaller the dimming signal is, the smaller the dip coefficient K is; when the dimming signal is less than or equal to the second threshold, the dip coefficient K is a second fixed value. The dimming signal is a PWM signal or an analog signal.
As shown in fig. 4, a schematic diagram of a second embodiment of the dimming circuit of the present invention is illustrated, which is different from the first embodiment in that: the reference signal VREF is a given signal, and the feedback signal VCS is obtained by adjusting the feedback circuit U201 through a dimming signal.
although the embodiments have been described and illustrated separately, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and reference may be made to one of the embodiments not explicitly described, or to another embodiment described.
the above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.
Claims (8)
1. The utility model provides a LED dimming circuit, alternating current input power obtains input voltage after rectifier circuit rectification, input voltage to LED load power supply which characterized in that: the LED dimming circuit controls load current according to the dimming signal, and the dimming signal is an analog signal or a PWM signal; in a half power frequency period, the load current waveform is concave, the dimming signal adjusts the concave coefficient of the load current waveform, and the concave coefficient represents the concave degree of the load current waveform.
2. The LED dimming circuit of claim 1, wherein:
when the dimming signal is greater than or equal to a first threshold value, the sinking coefficient is a first fixed value;
When the dimming signal is greater than a second threshold and smaller than a first threshold, the dip coefficient is smaller than a first fixed value and larger than a second fixed value, and the smaller the dimming signal is, the smaller the dip coefficient is;
when the dimming signal is less than or equal to the second threshold, the dip coefficient is a second fixed value.
3. the LED dimming circuit according to claim 1 or 2, wherein: the LED dimming circuit comprises a compensation circuit, a reference signal or a feedback signal representing load current is obtained according to the dimming signal, the compensation circuit receives the reference signal and the feedback signal, the compensation circuit compensates errors of the reference signal and the feedback signal and outputs compensation voltage, and the compensation voltage controls load average current.
4. The LED dimming circuit of claim 3, wherein: the LED dimming circuit further comprises a sinking coefficient adjusting circuit, a sinking compensation circuit and a first control circuit, wherein the sinking coefficient adjusting circuit receives the dimming signal and outputs the sinking coefficient; the sinking compensation circuit receives the sinking coefficient and a sampling signal representing input voltage and outputs a sinking control signal; the first control circuit receives the compensation voltage and the sinking control signal and outputs a first control signal, and the first control signal controls the load current.
5. an LED dimming method, an AC input power supply obtains an input voltage after being rectified by a rectifying circuit, the input voltage supplies power to an LED load, and the LED dimming method is characterized in that: the LED dimming circuit controls load current according to the dimming signal, and the dimming signal is an analog signal or a PWM signal; in a half power frequency period, the load current waveform is concave, the concave coefficient of the load current waveform is adjusted according to the dimming signal, and the concave coefficient represents the concave degree of the load current waveform.
6. the LED dimming method according to claim 5, wherein:
when the dimming signal is greater than or equal to a first threshold value, the sinking coefficient is a first fixed value;
When the dimming signal is greater than a second threshold and smaller than a first threshold, the dip coefficient is smaller than a first fixed value and larger than a second fixed value, and the smaller the dimming signal is, the smaller the dip coefficient is;
When the dimming signal is less than or equal to the second threshold, the dip coefficient is a second fixed value.
7. the LED dimming method according to claim 5 or 6, wherein: and obtaining a reference signal or a feedback signal representing the load current according to the dimming signal, compensating the error of the reference signal and the feedback signal to obtain a compensation voltage, and controlling the load average current by the compensation voltage.
8. An LED control circuit, characterized by: comprising the LED dimming circuit of any of claims 1-4.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910952283.2A CN110582143B (en) | 2019-10-09 | 2019-10-09 | LED dimming circuit, dimming method and LED control circuit |
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| CN201910952283.2A CN110582143B (en) | 2019-10-09 | 2019-10-09 | LED dimming circuit, dimming method and LED control circuit |
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| CN110582143A true CN110582143A (en) | 2019-12-17 |
| CN110582143B CN110582143B (en) | 2024-06-28 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112533326A (en) * | 2019-12-30 | 2021-03-19 | 杰华特微电子（杭州）有限公司 | Linear LED drive circuit |
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2019
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| CN102573208A (en) * | 2010-10-25 | 2012-07-11 | 松下电器产业株式会社 | Dimming device and lighting apparatus using same |
| CN102740571A (en) * | 2012-07-18 | 2012-10-17 | 矽力杰半导体技术(杭州)有限公司 | Dimmable LED (Light-Emitting Diode) driving circuit and driving method |
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| CN112533326B (en) * | 2019-12-30 | 2023-06-23 | 杰华特微电子股份有限公司 | Linear LED driving circuit |
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| CN110582143B (en) | 2024-06-28 |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Applicant before: JOULWATT TECHNOLOGY Inc.,Ltd. |
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