Disclosed herein is an LED driver chip capable of being used for master chip and slave chip. In case that the LED driver chip of the disclosure is used for the master, the strobe clock signal may be used as a reference clock signal. The 1-st to the n-th frequency clock signals, which are relatively simple to generate, may be provided as the 1-st to the n-th gray clock signals. In case that the LED driver chip of the disclosure is used for the slave, the external clock signal may be used as a reference clock signal. The 1-st to the n-th delay clock signals, which have a phase according to the reference clock signal, may be provided as the 1-st to the n-th gray clock signal. As a result, the LED driver chip of the disclosure can be used for both a master chip and a slave chip.