In the drive of LED, we often mention linear constant current. What circuit structure is linear constant current?
1. Linear constant current drive IC, that is, constant current chip led lamp, all circuits are nothing more than resistors, capacitors, inductors, and some transistors. Constant current is mainly driven by constant current IC, which means constant current. Generally, when the input voltage changes, the input current remains constant.
2.) less rest product: the volume of linear constant current drive is relatively small, and the application is more flexible, such as the three-way output of dot crystal DD313, the volume of the package is even smaller than our common SOP package.
3. You should be clear about the intention of constant current source and PWM. The constant current source is to make the LED glow stably. PWM is the pulse width modulation. Its purpose is not to stabilize, but to adjust the light. It is a constant way to adjust the luminous intensity of LED. The purposes of the two are different, so they are not contradictory.
4. Because if the battery drives the LED directly, the output voltage and current of the battery will gradually decrease, which will cause the instability of the strong light. With the addition of the drive board, it will be automatically adjusted so that the output voltage is always stable.
5. Most LED use constant current control, which can maintain the stability of LED current, is not easy to be changed by VF, and can prolong the service life of LED lamps. Like ordinary diodes, light-emitting diodes are composed of a PN junction and have unidirectional conductivity.
6. Pulse Width Modulation (PWM) digitize the square wave of the power supply and control the duty cycle of the square wave, so as to achieve the purpose of controlling the current. Constant current power supply regulation can easily adjust the current by using analog linear technology. Grouping regulation: multiple LED are grouped and regulated by a simple grouper.
What kind of curve is the characteristic curve of LED light source
The main results are as follows: 1. The Imurv characteristic curve of LED describes the variation of current with voltage. The curve is the same as that of an ordinary diode. In the initial stage, the voltage is very low, when the forward voltage is less than a certain value, there is no current flow, when the voltage exceeds a certain value, the forward current increases rapidly with the voltage and glows.
2. The led light decay curve will not be a wavy line, but a parabola. LED luminous efficiency: commonly known as the external quantum efficiency of a component, which is the product of the internal quantum efficiency of the component and the extraction efficiency of the component.
3. The definition of light distribution curve: the light distribution curve actually represents the distribution of light emitted by a lamp or light source in space. It can record the luminous flux, the number of light sources, power, power factor, lamp size, lamp efficiency, including lamp manufacturer, model and other information.
4. the so-called light distribution curve refers to the light intensity distribution map, in which the light intensity in a certain direction leads a ray from the central point to that direction, and the length of the line formed by the intersection with the matching light is the light intensity in that direction. Illuminance is the intensity of light divided by the square of the distance.
5. A complete volt-ampere curve includes forward and reverse characteristics. Usually, the change of the reverse characteristic curve is steep, and the current increases exponentially when the voltage exceeds a certain threshold. Usually, reverse breakdown voltage, reverse current and forward voltage can be used to describe the volt-ampere characteristic curve.
6. There are different light distribution curves according to the angle of LED. At present, the main luminous angles of LED are 15 °, 30 °, 60 °, 90 °, 120 °and 170 °. Of course, it is also possible that the light distribution curve is different at the same luminous angle.
Does EMC Linear Scheme have to pass LED?
1. National laws and regulations, such as CCC requirements. Electromagnetic environment requires that if the LED power supply is only EMI and EMC, it is possible that its own electromagnetic interference will affect the normal operation of other electronic devices in your home. It can improve the anti-interference performance and product quality of the product.
2. Strictly speaking, all electronic devices need EMI testing. Electronic devices with excessive EMI not only work unsteadily, but also affect other electronic devices, and radioactive EMI may even affect the human body. Because the power supply is for other devices, EMI is particularly important in the power supply design.
3. There are no compulsory requirements at home for the time being, if there are certain requirements abroad. For example, to go to Europe, you can do CE, because you are 24V low voltage, you only need to do the EMC test. Mainly depends on where your market is, specific analysis of specific problems.
Is the linear lamp LED light?
1. When the linear lamp is broken, it is easy to replace. The first technique is to look at the glue because the glue material is too poor, the line lights will turn yellow seriously after a year. The inferior glue named waterproof PU glue on the market has poor waterproof performance and is easy to yellowing. The price of waterproof PU glue is very different from that of ordinary waterproof PU glue.
2. Line lights are LED line lights. LED line lamp series is a high-end flexible decorative lamp, which is characterized by low power consumption, long life, high brightness, easy to bend, maintenance-free and so on. It is especially suitable for indoor and outdoor entertainment, building outline drawing and billboard production.
3. Yes. According to Jinri Toutiao, linear lights can be installed in grooves 10 centimeters away from the wall. Linear lights are LED line lights. LED line lamp series is a kind of high-end flexible decorative lamp.
4, is the use of LED as a light source lamps and lanterns, as a building location, generally 10 to dozens of hundreds of LED light-emitting tubes combined into a light-emitting unit, called LED linear spotlight. It is characterized by convenient installation, long life and energy saving. But the price is relatively high.
5. No. As long as the lamp is fixed to prevent it from falling off, the line lamp refers to welding the LED lamp on the copper wire or ribbon flexible circuit board with special processing technology, and then connecting the power supply to glow, which is named because it is shaped like a light band when it glows.
6. The two thin slices of the tile lamp can be inserted. The color of the tile lamp is very close to that of the tile, so it will not affect the daytime building effect of the roof. At night, patches of LED tile lights come on, creating a spectacular roofing effect.
What is the special built-in power supply for LED linear lighting for?
1. LED switching power supply has a circuit to control the switch tube for high-speed channel pass and cut-off. Is to convert DC current into high-frequency AC power to convert the converter to generate one or more groups of voltages needed! The reason for converting to high-frequency AC is that high-frequency AC is more efficient in transformer circuits than municipal power 50Hz or 60Hz.
2. The concept should be clarified first. The so-called “led power supply” is not a power supply that can provide electricity, but a power conversion controller. Because the city electricity is 220V AC, and the led works in DC, and the voltage and current should be matched, so it is necessary to convert and control the city power.
3. The meaning of the built-in power supply is that the LEDT8 is directly connected to AC 220V, that is, your lamp foot is directly connected to 220V. External power supply, LEDT8 can not be directly connected to alternating current, need to adapt the power supply, that is, the power supply is installed in the lamp rack, the power supply is connected to 220V LED DT8 installed on the lamp rack.
4. Call switch power supply or LED control device. It is a kind of converter, the LED lamp needs low voltage direct current to work, and the switching power supply converts 220V voltage into low voltage direct current device.
