ICS8431-01

The ICS8431-01 is a general purpose clock frequency synthesizer for IA64/32 application and a member of the HiPerClockS™ family of High Performance Clock Solutions from ICS. The ICS8431-01 consists of one independent low bandwidth PLL timing channel. A 16.666MHz crystal is used as the input to the on-chip oscillator. The M is configured to produce a fixed output frequency of 200MHz.

Programmable features of the ICS8431-01 support four operational modes. The four modes are spread spectrum clocking (SSC), non-spread spectrum clock and two test modes which are controlled by the SSC_CTL[1:0] pins. Unlike other synthesizers, the ICS8431-01 can immediately change spread-spectrum operation without having to reset the device.

In SSC mode, the output clock of the ICS8431-01 is modulated in order to achieve a reduction in EMI. In one of the PLL bypass test modes, the PLL is disconnected as the source to the differential output allowing an external source to be connnected to the TEST_I/O pin. This is useful for incircuit testing and allows the differential output to be driven at a lower frequency throughout the system clock tree. In the other PLL bypass mode, the oscillator divider is used as the source to both the M and the Fout divide by 2. This is useful for characterizing the oscillator and internal dividers.