CN210579344U - LED control circuit - Google Patents
LED control circuit Download PDFInfo
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- CN210579344U CN210579344U CN201921055324.XU CN201921055324U CN210579344U CN 210579344 U CN210579344 U CN 210579344U CN 201921055324 U CN201921055324 U CN 201921055324U CN 210579344 U CN210579344 U CN 210579344U
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Abstract
The utility model provides a LED control circuit, AC input supplies power for the load after the rectification, detects the temperature of LED control circuit in order to control load current, when the temperature that detects is less than first threshold value, load current is the constant current, load current is first electric current; when the detected temperature is higher than the first threshold and lower than the second threshold, the load current waveform is concave, the average values of the load currents at different temperatures are equal, and the load current is the second current; when the detected temperature is larger than the second threshold and smaller than the third threshold, the load current waveform is concave, the higher the temperature is, the smaller the average value of the load current is, and the load current is the third current. The utility model discloses can optimize circuit system's efficiency, and the flexibility is higher.
Description
Technical Field
The utility model relates to a power electronics field, in particular to LED control circuit.
Background
In the prior art, referring to fig. 1, a schematic diagram of a prior art LED control circuit is illustrated, where an ac input is rectified to obtain an input voltage for supplying power to an LED load. The LED control circuit comprises a regulating tube M0 and a first operational amplifier U01. The first end of the adjusting tube M0 is connected with the low potential end of the LED load, the second end of the adjusting tube M0 is grounded through a sampling resistor Rs, the first input end of the first operational amplifier U01 receives a reference voltage VREF, the second input end of the first operational amplifier U01 is connected with the second end of the adjusting tube M0, and the output end of the first operational amplifier U01 is connected with the control end of the adjusting tube M0. In the prior art, the LED load current is controlled to be constant current through a given reference voltage VREF, extra power loss is caused on a regulating tube M0 and a sampling resistor Rs, and the efficiency of a circuit system is low.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a LED control circuit for solve the problem that the system efficiency is low that prior art exists.
In order to realize the above object, the utility model provides a LED control circuit, alternating current input gives the load power supply after the rectification, detects LED control circuit's temperature in order to control load current, LED control circuit includes that adjusting tube and first fortune are put, load low potential end is connected to adjusting tube first end, adjusting tube second end is through sampling resistance ground connection, first fortune is put first end and is received reference voltage, first fortune is put the second and is held and connect adjusting tube second end, adjusting tube control end is connected to first fortune output, obtains according to the LED control circuit's that detects temperature reference voltage.
Optionally, the LED control circuit further comprises a reference generating circuit, the reference generating circuit receives the detected temperature of the LED control circuit and outputs the reference voltage,
when the detected temperature is less than a first threshold value, the reference voltage is a constant voltage;
when the detected temperature is higher than the first threshold and lower than the second threshold, the reference voltage waveform is concave, and the average values of the reference voltage control load current at different temperatures are equal;
when the detected temperature is higher than the second threshold and lower than the third threshold, the reference voltage waveform is concave, and the higher the temperature is, the smaller the reference voltage is;
when the detected temperature is greater than the third threshold, the reference voltage is zero.
Optionally, when the reference voltage waveform is concave, the concave shape or/and concave time of the reference voltage is adjusted according to the detected temperature of the LED control circuit.
Optionally, the reference generating circuit includes a second operational amplifier, a first input end of the second operational amplifier receives a first voltage signal representing an average value of the load current, a second input end of the second operational amplifier receives a load current sampling signal, and the second operational amplifier outputs a first control voltage;
when the detected temperature is less than a second threshold value, the first voltage is a constant voltage;
when the detected temperature is greater than the second threshold and less than the third threshold, the higher the temperature is, the smaller the first voltage is;
when the detected temperature is greater than a third threshold, the first voltage is zero.
Optionally, the reference generating circuit further includes a multiplier, where the multiplier multiplies the voltage at the first end of the regulating tube by the first regulating coefficient, and outputs a second control voltage; the difference value of the first control voltage and the second control voltage is the reference voltage;
when the detected temperature is less than a first threshold value, the first adjusting coefficient is zero;
when the detected temperature is greater than a first threshold and less than a second threshold, the higher the temperature is, the larger the first adjusting coefficient is;
when the detected temperature is greater than the second threshold and less than the third threshold, the higher the temperature is, the first adjusting coefficient is unchanged or is larger;
when the detected temperature is greater than a third threshold, the first adjustment factor is zero.
Optionally, the reference generating circuit further comprises a first capacitor, and the first capacitor is charged with a first regulating current before the load supply voltage rises to its maximum value; discharging the first capacitor with a second regulated current before the load supply voltage drops to its minimum value; the voltage on the first capacitor is a second control voltage, and the difference value between the first control voltage and the second control voltage is the reference voltage;
when the detected temperature is less than a first threshold, the first regulating current and the second regulating current are zero;
when the detected temperature is greater than a first threshold and less than a second threshold, the higher the temperature is, the larger the first regulating current and the second regulating current are;
when the detected temperature is greater than a second threshold and less than a third threshold, the first regulating current and the second regulating current are unchanged or are larger as the temperature is higher;
when the detected temperature is greater than a third threshold, the first and second regulated currents are zero.
Compared with the prior art, the utility model has the advantages of it is following: the method comprises the steps that alternating current input is rectified and then supplies power to a load, the temperature of an LED control circuit is detected to control load current, when the detected temperature is smaller than a first threshold value, the load current is constant current, and the load current is first current; when the detected temperature is higher than the first threshold and lower than the second threshold, the load current waveform is concave, the average values of the load currents at different temperatures are equal, and the load current is the second current; when the detected temperature is higher than the second threshold and lower than the third threshold, the load current waveform is concave, the higher the temperature is, the smaller the average value of the load current is, and the load current is the third current; when the detected temperature is greater than a third threshold, the load current is zero. The utility model discloses can improve system efficiency, and the flexibility is higher.
Drawings
FIG. 1 is a schematic diagram of a prior art LED control circuit;
FIG. 2 is a schematic diagram of a first LED control circuit of the present invention;
FIG. 3 is a schematic diagram of a second LED control circuit of the present invention;
FIG. 4 is a waveform diagram illustrating the operation of the LED control circuit of the present invention;
Detailed Description
The 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 present invention covers any alternatives, modifications, equivalents, and alternatives falling within the spirit and scope of the present 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 simplified and in non-precise proportion, so as to facilitate and clearly assist in explaining the embodiments of the present invention.
As shown in fig. 2, the utility model discloses a LED control circuit schematic diagram, the AC input obtains input voltage Vin after rectifier circuit and gives the LED load power supply, LED control circuit includes temperature sampling circuit U01, benchmark generating circuit U02, first fortune is put U03 and adjusting tube M0, and temperature sampling circuit U01 detects LED control circuit's temperature, and the benchmark generating circuit U02 input is connected to temperature sampling circuit U01 output, obtains reference voltage VREF according to the LED control circuit's that the detection obtained temperature. The first end of the adjusting tube M0 is connected with a low-potential end of an LED load, the second end of the adjusting tube M0 is grounded through a sampling resistor R01, the first end of the first operational amplifier U03 receives a reference voltage VREF, the second end of the first operational amplifier U03 is connected with the second end of the adjusting tube M0, and the output end of the first operational amplifier U03 is connected with the control end of the adjusting tube M0. When the detected temperature Ts is less than a first threshold T1, controlling the reference voltage VREF to be a constant voltage and the load current iLED to be a constant current; when the detected temperature Ts is greater than a first threshold T1 and less than a second threshold T2, controlling the waveform of the reference voltage VREF to be concave, controlling the waveform of the load current iLED to be concave, and enabling the average values of the load current iLED to be equal at different temperatures; when the detected temperature Ts is greater than the second threshold T2 and less than the third threshold T3, controlling the waveform of the reference voltage VREF to be concave, wherein the higher the temperature Ts, the smaller the reference voltage VREF, and the smaller the average value of the load current iLED; when the detected temperature Ts is greater than the third threshold T3, the tuning tube M0 is turned off, and the reference voltage VREF and the load current iLED are zero. When load current iLED wave form is concave type, according to the temperature that detects LED control circuit, adjust load current iLED's recessed shape or/and recessed time, recessed shape is including recessed degree, and linear recessed or curve are recessed etc..
The reference voltage regulating circuit U02 comprises a coefficient regulating circuit U201, an average value regulating circuit U202, a second operational amplifier U203, a multiplier U204 and a difference device U205. The average value adjusting circuit U202 receives the detected temperature Ts and outputs a first voltage V1 representing the average value of the load current; when the detected temperature Ts is less than a second threshold T2, the first voltage V1 is a constant voltage; when the detected temperature Ts is greater than the second threshold T2 and less than the third threshold T3, the higher the temperature Ts, the smaller the first voltage V1; when the detected temperature is greater than a third threshold T3, the first voltage V1 is zero. The inverting input terminal of the first operational amplifier U203 receives the load current sampling signal VCS, the non-inverting input terminal thereof receives the first voltage signal V1, and the output terminal thereof outputs the first control voltage VC 1. The coefficient adjusting circuit U201 receives the detected temperature Ts and outputs a first adjustment coefficient k 1; when the detected temperature Ts is less than a first threshold T1, the first adjustment coefficient k1 is zero; when the detected temperature Ts is greater than the first threshold T1 and less than the second threshold T2, the higher the temperature Ts, the larger the first adjustment coefficient k 1; when the detected temperature Ts is greater than the second threshold T2 and less than the third threshold T3, the higher the temperature Ts, the higher the first adjusting coefficient k1 is constant or larger; when the detected temperature Ts is greater than the third threshold T3, the first adjustment coefficient k1 is zero. The multiplier U204 multiplies the first adjustment coefficient k1 by the voltage VD at the first end of the tuning tube to obtain a second control voltage VC 2. The differentiator U205 takes the difference obtained by subtracting the first control voltage VC1 and the second control voltage VC2 as the reference voltage VREF.
As shown in fig. 3, the schematic diagram of the second LED control circuit of the present invention is illustrated, which is different from the first LED control circuit only in the difference of the reference generating circuit U02, and the shape of the load current iLED obtained by the control circuit is different from the shape of the load current iLED obtained by the first LED control circuit. The reference voltage generating circuit U02 of this embodiment includes a supply voltage sampling circuit U201, an average current adjusting circuit U202, a second operational amplifier U203, a first current source I1, a second current source I2, a first capacitor C01, and a differentiator U204, wherein the first current source I1 outputs a first adjusting current, and the second current source I2 outputs a second adjusting current. The average value adjusting circuit U202 receives the detected temperature Ts and outputs a first voltage V1 representing the average value of the load current; when the detected temperature Ts is less than a second threshold T2, the first voltage V1 is a constant voltage; when the detected temperature Ts is greater than the second threshold T2 and less than the third threshold T3, the higher the temperature Ts, the smaller the first voltage V1; when the detected temperature is greater than a third threshold T3, the first voltage V1 is zero. The inverting input terminal of the first operational amplifier U203 receives the load current sampling signal VCS, the non-inverting input terminal thereof receives the first voltage signal V1, and the output terminal thereof outputs the first control voltage VC 1. The input end of the supply voltage sampling circuit U201 is connected with the load input end, and the output sampling voltage controls the on-off of the first current source I1 and the second current source I2. When the load supply voltage VIN rises to its maximum value, the first current source I1 is turned on, and outputs a first regulated current to charge the first capacitor C01; before the load supply voltage VIN drops to its minimum value, the second current source I2 is turned on, and outputs a second regulated current to discharge the first capacitor C02, and the voltage across the first capacitor C01 is the second control voltage VC 2. When the detected temperature Ts is less than a first threshold T1, the first and second regulation currents are zero; when the detected temperature Ts is greater than a first threshold T1 and less than a second threshold T2, the higher the temperature Ts, the larger the first adjustment current and the second adjustment current; when the detected temperature Ts is greater than the second threshold T2 and less than the third threshold T3, the higher the temperature Ts, the same or larger the first adjustment current and the second adjustment current; when the detected temperature Ts is greater than a third threshold T3, the first and second regulation currents are zero. The differentiator U204 takes the difference obtained by subtracting the first control voltage VC1 and the second control voltage VC2 as the reference voltage VREF.
As shown in fig. 4, illustrating the working waveform diagram of the LED control circuit of the present invention, when the detected temperature Ts is less than the first threshold T1, the load current iLED is a constant current, and the load current is a first current of iLED; when the detected temperature Ts is greater than a first threshold T1 and less than a second threshold T2, the waveform of the load current iLED is concave, the average values of the load current iLED at different temperatures are equal, and the load current iLED is a second current; when the detected temperature Ts is greater than the second threshold T2 and less than the third threshold T3, the waveform of the load current iLED is concave, the higher the temperature is, the smaller the average value of the load current iLED is, and the load current iLED is the third current; when the detected temperature is greater than the third threshold T3, the load current iLED is zero. When the waveform of the load current iLED is concave, the concave shape or/and concave time of the load current iLED can be adjusted according to the detected temperature of the LED control circuit. The first current and the second current are equal in average value and larger than the third current average value.
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 (6)
1. The utility model provides a LED control circuit, alternating current input supplies power for the load after the rectification which characterized in that: the temperature of the LED control circuit is detected to control load current, the LED control circuit comprises an adjusting tube and a first operational amplifier, the first end of the adjusting tube is connected with a low-potential end of a load, the second end of the adjusting tube is grounded through a sampling resistor, the first end of the first operational amplifier receives reference voltage, the second end of the first operational amplifier is connected with the second end of the adjusting tube, the output end of the first operational amplifier is connected with the control end of the adjusting tube, and the reference voltage is obtained according to the detected temperature of the LED control circuit.
2. The LED control circuit of claim 1, wherein: the LED control circuit further comprises a reference generating circuit, the reference generating circuit receives the detected temperature of the LED control circuit and outputs the reference voltage,
when the detected temperature is less than a first threshold value, the reference voltage is a constant voltage;
when the detected temperature is higher than the first threshold and lower than the second threshold, the reference voltage waveform is concave, and the average values of the reference voltage control load current at different temperatures are equal;
when the detected temperature is higher than the second threshold and lower than the third threshold, the reference voltage waveform is concave, and the higher the temperature is, the smaller the reference voltage is;
when the detected temperature is greater than the third threshold, the reference voltage is zero.
3. The LED control circuit of claim 2, wherein: and when the reference voltage waveform is concave, adjusting the concave shape or/and concave time of the reference voltage according to the detected temperature of the LED control circuit.
4. The LED control circuit of claim 3, wherein: the reference generating circuit comprises a second operational amplifier, wherein a first input end of the second operational amplifier receives a first voltage signal representing the average value of the load current, a second input end of the second operational amplifier receives a load current sampling signal, and the second operational amplifier outputs a first control voltage;
when the detected temperature is less than a second threshold value, the first voltage is a constant voltage;
when the detected temperature is greater than the second threshold and less than the third threshold, the higher the temperature is, the smaller the first voltage is;
when the detected temperature is greater than a third threshold, the first voltage is zero.
5. The LED control circuit of claim 4, wherein: the reference generating circuit also comprises a multiplier, and the multiplier multiplies the voltage at the first end of the adjusting tube by a first adjusting coefficient and outputs a second control voltage; the difference value of the first control voltage and the second control voltage is the reference voltage;
when the detected temperature is less than a first threshold value, the first adjusting coefficient is zero;
when the detected temperature is greater than a first threshold and less than a second threshold, the higher the temperature is, the larger the first adjusting coefficient is;
when the detected temperature is greater than the second threshold and less than the third threshold, the higher the temperature is, the first adjusting coefficient is unchanged or is larger;
when the detected temperature is greater than a third threshold, the first adjustment factor is zero.
6. The LED control circuit of claim 4, wherein: the reference generation circuit further comprises a first capacitor which is charged with a first regulated current before the load supply voltage rises to its maximum value; discharging the first capacitor with a second regulated current before the load supply voltage drops to its minimum value; the voltage on the first capacitor is a second control voltage, and the difference value between the first control voltage and the second control voltage is the reference voltage;
when the detected temperature is less than a first threshold, the first regulating current and the second regulating current are zero;
when the detected temperature is greater than a first threshold and less than a second threshold, the higher the temperature is, the larger the first regulating current and the second regulating current are;
when the detected temperature is greater than a second threshold and less than a third threshold, the first regulating current and the second regulating current are unchanged or are larger as the temperature is higher;
when the detected temperature is greater than a third threshold, the first and second regulated currents are zero.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921055324.XU CN210579344U (en) | 2019-07-08 | 2019-07-08 | LED control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921055324.XU CN210579344U (en) | 2019-07-08 | 2019-07-08 | LED control circuit |
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| Publication Number | Publication Date |
|---|---|
| CN210579344U true CN210579344U (en) | 2020-05-19 |
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| CN201921055324.XU Active CN210579344U (en) | 2019-07-08 | 2019-07-08 | LED control circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110392467A (en) * | 2019-07-08 | 2019-10-29 | 杰华特微电子（杭州）有限公司 | LED control circuit and control method |
| CN113805636A (en) * | 2020-06-16 | 2021-12-17 | 华润微集成电路(无锡)有限公司 | Current regulating circuit based on external resistor |
-
2019
- 2019-07-08 CN CN201921055324.XU patent/CN210579344U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110392467A (en) * | 2019-07-08 | 2019-10-29 | 杰华特微电子（杭州）有限公司 | LED control circuit and control method |
| CN110392467B (en) * | 2019-07-08 | 2024-03-22 | 杰华特微电子股份有限公司 | LED control circuit and control method |
| CN113805636A (en) * | 2020-06-16 | 2021-12-17 | 华润微集成电路(无锡)有限公司 | Current regulating circuit based on external resistor |
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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 Patentee after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Patentee before: JOULWATT TECHNOLOGY (HANGZHOU) Co.,Ltd. |