A display driver IC includes a register map, an oscillator, a timing controller, an oscillator scatter, and an intellectual property (IP) block. The register map is configured to store a trim code of a fixed frequency and scatter option information. The oscillator is configured to generate an oscillator clock based on the trim code. The timing controller is configured to generate an internal synchronization signal based on the oscillator clock. The oscillator scatter is configured to output a modified trim code to the oscillator based on the trim code, the scatter option information, and the internal synchronization signal. The intellectual property (IP) block is configured to receive a modified oscillator clock generated in the oscillator based on the modified trim code.