| LED, as a new energy-saving and environment-protecting technology, performs a role so irreplaceable that government,capital,and enterprises all focus on it. Contrast to the traditional light-emitting sources, LED maintains its advantages as: high efficiency light-emitting,electricity power-saving,long life time,safety,reliability and so on. LED industry development cannot only contribute to the country economy, which potentially meets the current trend of low carbon economy.Every coin has its two sides. LED is not perfect for its non-uniformity for light, which raises designers more challenge of the LED driver. Fortunately, permanent flow driver is mostly ideal choice. Since LED is applied to a wide variety of fields, respectively function-oriented drivers development per the special application requirements has become the new industry marketing orientation. This paper firstly analyzes the kinds of characteristics of LED,industry development trend,and issues facing, then makes a general description of the current status of LED driver, and focuses on the schematic of high-power LED driver—Buck,modulation mode,and controlling resolution. Following is the designing point: the hysteresis current controlling high-power LED constant-current driver with wide input voltage range and high dimming ratio. And then the paper tells the details about the architecture of the whole circuit design,running frequency of system,and dimmer schematics, after highlight of the three sub-block circuit—reference,bias,and dim_buffer. With the above full theories reparation, simulation has been done to test the various parameters of sub-block circuit and whole chip with Hspice, the result of which shows that index of whole system has targeted our goal. At last, after the analyzation of sub-circuit and whole system schematics and simulation of design, finally we finished the layout of sub-block circuit and whole circuit with Cadence and test and verify. |
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