A apparatus is provided for buffering data between a memory controller and a DRAM. The apparatus includes a phase locked loop (PLL), a phase interpolator for aligning a phase of an output clock signal in response to a phase aligning control word, and a non-volatile storage location permanently storing the phase aligning control word. The phase aligning control word is determined through an initial training procedure of the device under predetermined training conditions of at least a supply voltage level and a temperature, and the predetermined training conditions are set so as to optimize the phase alignment of an edge of the output clock signal with respect to the buffered data signal.