LED driver scheme selection discussion
1. LED driver IC features and choices
User question: LED driver must use a dedicated LED driver IC? What are the advantages and disadvantages compared with ordinary IC?
Expert reply: The advantages of LED driver IC are wide Vin, large output current, high constant current accuracy, and frequency hopping can effectively reduce EMI.
The constant current source for LED driving is mainly to ensure that the brightness of the LED during the working period of the LED is uniform and does not flicker. Low-cost mobile phones use LDO to drive backlight LEDs are also commonly used, but the power utilization rate is not high, but in most mobile phone design lithium battery voltage drop to 3.3V shutdown. It is not a good idea to drive LED lighting with LDO. LDO can't keep constant current.
User question: So how do you choose domestic and foreign LED driver ICs?
Expert reply: LED driver ICs are many, the cost performance is different, the key is to see the target price of the design products, such as seeking competitiveness and more profits, local IC products are also good.
2. LED drive power selection and design issues
User question: What issues to consider when selecting and designing LED driver
Expert reply: LED drive power is a voltage converter that converts the power supply into a specific voltage and current to drive the LED to emit light. Normally, the input of the LED drive power includes mains, low voltage DC, high voltage DC, low voltage high frequency AC, and the like. The output of the LED driver is mostly a constant current source that changes the voltage as the LED's forward voltage drop changes.
According to the power consumption rules of the power grid and the characteristics of the LED drive power supply, the following issues should be considered when selecting and designing the LED drive power supply.
a. High reliability is especially like the driving power of LED street lamps. It is installed at high altitude, it is inconvenient to maintain, and the maintenance cost is also large.
b. The high efficiency power supply has high efficiency, its power consumption is small, and the heat generated in the lamp is small, which reduces the temperature rise of the lamp. It is beneficial to delay the light decay of LEDs.
c. There are two types of driving methods: one is a constant voltage source for multiple constant current sources, and each constant current source supplies power to each LED separately. The other is direct constant current supply, with LEDs running in series or in parallel. How to choose the startup method should be based on actual needs. Multi-channel constant current output power supply mode will be better in terms of cost and performance. Perhaps it is the mainstream direction in the future.
d. The ability of surge protection LEDs to resist surges is relatively poor, especially against reverse voltage capability. Due to the start of the grid load and the induction of lightning strikes, various surges will be invaded from the grid system, and some surges will cause LED damage. Therefore, the LED driver power supply must have the ability to suppress the intrusion of surges and protect the LEDs from damage.
e. Other factors, such as improving the power factor of the power supply; increasing the negative feedback function of the LED temperature; for external protection, it is waterproof and moisture-proof, and the outer casing is resistant to light; the life of the driving power supply should be compatible with the life of the LED; And electromagnetic compatibility requirements.
Currently, the outdoor media are mainly composed of text spraying and LED outdoor advertising screen. The outdoor advertising screen is also the most popular way of media, but it is regulated by the government, so the area and location must be approved. After the approval, the steel structure and screen body shall be customized according to the site conditions. So the main cost ways of Outdoor Led Display are: Led Display, steel structure, surrounding products and product electricity. Outdoor LED display as a commercial, investment and advertising is the main source of income. Of course, with the popularity of LED outdoor screens, more and more are used for lighting, store layout, and become a bright landscape in a modern metropolis.
LED outdoor advertising screen features:
1. Strong visual impact, dynamic picture and sound, all-round let the audience feel, effectively transmit advertising information to guide consumption. In the face of overwhelming advertising, memory limitations and unlimited information dissemination, the use of LED display has become a scarce resource.
2. According to the shape of the wall, it can be straight or curved. Shape diversity creates more personalization and strong visual impact.
3. The credibility of the audience is high. Compared with the rejection and distrust of the advertising flyers artificially distributed on the street, the application of LED display makes the audience more active and passive. It can avoid the help barriers caused by the conscious active avoidance of the advertising audience, and greatly improve the credibility and promotion of the Led Screen advertising content.
4. Accurate advertising, the original extensive advertising effect is not good, resulting in waste, so it is more product content to meet the needs of the masses, hot news, hot TV and movies can be used for reference, to control the market heat and laws freely.
Product structure: outdoor LED display mainly consists of screen body, control system, heat dissipation system and structure. The control mode includes remote control and field control, timing switch, etc.
Outdoor Led Screen,Outdoor Fixed Led Display,Outdoor Fixed Led Display Screen,Outdoor Fixed Led Wall
Shenzhen Vision Display Technology Co,.LTD , https://www.ledvdi.com