The ICS615 is a low cost, low jitter, high performance PLL clock synthesizer designed to replace 13.5, 27, and 54MHz crystals and oscillators. Using analog/digital Phase-Locked Loop (PLL) techniques, the device uses an inexpensive external 13.5 MHz crystal or clock input to produce output clocks of 13.5 MHz, 27 MHz, and 54 MHz .