An introduction to DALI

摘要

The Digital Addressable Lighting Interface (DALI) is a standard that provides a single standard interface methodology for the digital control of lighting systems. This standard allows for the seamless integration of dimmable ballasts, LED drivers, relays and control panels from various manufacturers into one extremely versatile control system. DALI was established as a successor to current analogue dimmable systems and as an open standard alternative to the Digital System Interface. The dimmable electronic ballasts of existing analogue dimming systems typically consist of an Application Specific Integrated Circuit (ASIC) to take control of the dimming functionality along with a number of other essential blocks. Firstly, an EMI filtering block is required to prevent the noise generated by the ballast from being returned to the mains. The mains voltage is then rectified and power factor corrected on its way to the ballast output driving stage. The required dimming level of the lamp is set by the application of an external analogue control voltage which is typically in the range of 1 to 10 volts DC. This voltage must be galvanically isolated from the potentially dangerous voltages within the ballast and serves as a reference to the ASIC to set the required current level in the lamp.