Intelligent Lighting Solution Based on English Flying Ling XMC1200 MCU. MCU can help achieve LED lighting intelligence. LED lighting system dealers can rely on the MCU of the built-in BCCU feature, significantly shorten the development time to develop intelligent high-power LED bulbs, and help end users reach the purpose of easily and precise dimming while avoiding flickering. The UFC XMC1200 as a single-chip solution for the above features, saving a large number of CPU overhead, significantly reduces software development, and effectively reduce human-oriented software errors. Risk. At the same time, the XMC1200 Series MCU has high performance, large capacity, high reliability, which can be widely used in intelligent lighting to life and industrial aspects.
Decorgenated lamp control modulation, the LED switch switching speed is key. The change refers to the quick switch LED. If the switching speed is fast enough, the human eye cannot identify, and the brightness that will be seen will depend on the average time of the LED. The most common modulation mode is the pulse width modification (PWM) and pulse density modification (PDM) (Figure 2). Among them, the PDM can achieve higher resolution at a peer-to-peer system, and the electromagnetic interference (EMI) characteristics is better, and because it is high, it is not easy to flash.
Figure 1- approximately 25% brightness PWM and PDM modulation
The power supply and drive are included in the control device of the outdoor LED bulb. Among them, important devices of standard power supply include bridging stream, power factor corrector (PFC), and half-bridge resonant (LLC) resonance converters (Fig. 1).
Figure 2 - Quotation of the four channel LED lighting engine example
The LED current is fixed to a proliferated value, and the selected LED current depends on the system device and the highest brightness required, such as 350 mA culture (MA) or 700 mApe. The LEDs of the general street light are driven by the same current, and the multi-color bulbs used frequently in building lighting, they may use a completely different LED channel current. When dimming, it is usually triggered by communication, such as digital addressable lighting interface (DALI) or sensor input (such as ambient light source); the brightness and / or color of the bulb is input through the modulation drive (Enable INPUT) Control.
The microcontroller (MCU) developed by the industry is applicable to LED lighting, including brightness and color control unit (BCCU), which can generate PDM signals on up to nine channels. Special challenges for high-power dimming bulbs is that the LED driver requires the shortest residence time, and the change signal of the LED driver Enable INPUT must remain constant in the shortest time interval. From the experience, it is known that the higher the power, the longer the shortest residence time required, and only this can maintain a stable and accurate LED current. However, in the case of high resolution and high bit rate, especially in the case of low brightness, the change signal may violate this requirement.
At present, the industry is developing the MCU that is suitable for LED lighting, and the pulse within the adjustment signal is rearranged, and the problem is automatically solved. The pulse will be resolved in the packet circuit (Figure 3), generate a new pulse, has the shortest width required and the resolution, while remaining does not flash.
Figure 3 - Comparison of unpocked PDM and packet PDM examples
Another requirement is to minimize the load changes of the power supply (smooth load), especially the LLC resonant converter is extremely sensitive to high load changes. The packet circuit within the BCCU can add a phase shift between different relative channel adjustment, ensuring that the signal is changed at different time points.
Figure 4- System architecture diagram
Program characteristics
● Isolated DALI dimming interface
● Temperature detection
● Brightness detection of the surrounding environment
● 433MHz RF control method
Solution photo
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Source: Wiku Electronic Market Network
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