Memory device for supporting command bus training mode and method of operating the same

A method of operating a memory device, the method comprising:

• receiving a clock signal through a clock terminal;
• receiving a data clock signal through a data clock terminal;
• receiving a frequency set point (FSP) change command through a command/address (CA) bus, an operating frequency of the memory device being switched based on the FSP change command;
• receiving a first data signal through a first data terminal;
• detecting a logic level of the first data signal at one of a rising edge and a falling edge of the data clock signal, and entering into a command bus training (CBT) mode upon detecting a first logic level of the first data signal;
• and
• switching parameters of FSP operation settings based on the FSP change command during the CBT mode,
• wherein the parameters of the FSP operation settings includes a first FSP operation mode signal representing a low frequency setting in a normal mode, a second FSP operation mode signal representing an intermediate frequency setting in the normal mode, and a third FSP operation mode signal representing a high frequency setting in the normal mode.