HB - LED system design
HB - LED system design
Every intelligent lighting system contains the following basic building blocks (figure 1) : HB - LED, some type of power topology (only discuss switch mode voltage) and mixed signal controller. Designers first challenge is to choose LED. The main suppliers LED Lumileds including Cree, Nichia, etc, their Osram and rated power and electric products, scattering pattern, color, shape, size, thermal efficiency, characteristics and each package (bin) LED quantity are different. These parameters on the white light and color are the same, but also consider colour temperature and light colour developing index CRI.
Advanced industrial design and market demand of most often helps narrow range of LED characteristic parameters. In most cases, the design personnel should be in consideration of the characteristics of heat LED, take up the space is limited to the device or miniaturization and cannot use large radiator application should be so. Likewise, optical technology helps relieve scattering design problem, and mixed signal controller can significantly reduce the temperature and devices.
Should make clear above all the chosen separation components or integrated circuit, this is narrowing of intelligent lighting system for the first step of topological type power. Plan: separated tunable to specific system, so it is cheaper, more flexible, but occupy larger circuit design of space and professional technology. Power management IC offers a compact solution, although the cost is higher, but take up less space, and the circuit design more easily.
Secondly, according to the different lighting system efficiency, researchers in linear or switch to choose between topology. The importance of efficiency in two aspects. First, the higher power conversion efficiency and power waste, the less. Second, reduce power waste heat system means less. Linear regulators simpler, the cost is low, but usually poor efficiency.
Due to the need for switching voltage regulators and inductors and more complex, usually more expensive, but its efficiency is higher, regardless of how the input/output voltage regulator, which can obtain higher efficiency. Linear regulators and switching voltage regulators can single-chip IC design, also can use division component design. According to the power supply voltage of lighting system, design personnel should be correspondingly, choose to use pressor or fluctuation pressure switch topology. There is a weakness of linear topological can boost.
Again, the designer must choose one for intelligent lighting system of mixed signal controller. HB - LED the most intelligent system with flexibility is by this device, it can even solve HB - LED light brings some technical problems. Therefore, the choice is as high as many useful flexibility and mixed signal controller peripherals are very important. Normally, a kernel enough for most MCU application to provide enough to handle ability, and enough RAM or flash.
Designers should pay special attention to the device of MCU digital and analog peripherals. For digital devices, special hardware dimmer channel number and its resolution and achieve different communication interface ability is very important. Light stabilizer, used to drive the hypotensive channel software can also be used to realize the counter, although this function, but the software dimmer channels will consume the precious processing ability to execute other devices.
Intelligent lighting system usually use at least eight resolution to obtain high precision colour. If the system is high quality requirement, can use at 16 resolution. But for most applications, eight resolution enough to get the desired accuracy, designers often in low output level cases through higher resolution to achieve better GuangXianXing tone. Some designers are more intelligent switch the interpolation method to solve the low level of output change circumstances.
Common communication interface including SPI, UART and the I2C, but equally important is mixed signal controller, DALI, DMX512 support power communication rf communications and even the lighting is an important port. For analog peripherals, designers should note ADC and PGA and comparator. ADC can read the temperature sensor value through to support feedback, but also the temperature of the surrounding environment lighting system and various physical simulation of intelligence (interactive. The comparator and PGA can simplify power. Topological
In its most MCU manufacturers in the controller to provide part or all of these peripherals, but the design personnel may soon be found, along with the change of system requirements, peripherals varieties also happen corresponding change. Want to let the system design to take care of the prospective future innovation technology can really challenge, especially considering HB - LED lighting system itself is a kind of new things. If the system needs to be very high performance, so the FPGA would be a better value-for-money solutions. Has the configurable peripherals and routing I/O controller can provide maximum flexibility.
