A method for controlling operations of a delay locked loop (DLL) of a dynamic random access memory (DRAM) is provided herein. A phase detector of the DLL compares an external clock signal with a feedback clock signal to generate a first control signal. A delay line circuit of the DLL delays the external clock signal according to the first control signal. A detector of the DRAM detects variations of the first control signal to determine a length of an enable period of an enable signal. The delay line circuit and the output buffer are active only during the enable period when the DRAM is in a standby mode.