Patent attributes
The apparatus for driving LED display includes a system control unit having a synchronization signal generator configured to generate a synchronization start signal and a plurality of phase locked loop circuits. Each of the phase locked loop circuits includes a divider coupled to the voltage controlled oscillator and configured to change the sequence of dividing ratios over a modulation period, a sigma delta modulator configured to generate a sequence of random numbers to the divider, and a spread spectrum modulation depth controller coupled to the sigma delta modulator and configured to receive the synchronization start signal from the synchronization signal generator. Upon receipt of the synchronization start signal, the spread spectrum modulation depth controller starts a spread spectrum modulation.
