Abstract：Peak I2C control for lighting emitting diode (LED) driver to output constant current is investigated. In order to analyze the stability of peak I2C control, taking buck-based LED driver as an example, its control equation was established by Fourier series. The stable boundary equation was derived as well, which was simplified by the first-order Taylor series. With the increasing of the weight factor of output current in inner loop, the proportional term of compensator in outer loop increases, and the equivalent series resistance of LED varies. Their effects on the stability of LED driver were analyzed with the simplified boundary equation. It is found out that, when the equivalent series resistance of LED decreases, or the weight factor of output current and the proportional term of compensator increase, the stable region of the LED driver will be narrowed; slope compensation can extend the stable region by lessening the unstable phenomenon. Finally, the stability analysis is verified by computer simulation and hardware experiment.
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2018, Vol. 33 
