The ICS9161A is a fully programmable graphics clock generator. It can generate user-specified clock frequencies using an externally generated input reference or a single crystal. The output frequency is programmed by entering a 24-bit digital word through the serial port. Two fully userprogrammable phase-locked loops are offered in a single package. One PLL is designed to drive the memory clock, while the second drives the video clock. The outputs may be changed on-the-fly to any desired frequency between 390 kHz and 120 MHz. The ICS9161A is ideally suited for any design where multiple or varying frequencies are required.