ICS9248-66 Datasheet | Integrated Circuit Systems

Integrated Circuit Systems, Inc. Advance Information Frequency Timing Generator for PENTIUM II Systems Features • Generates the following system clocks: - 3 CPU clocks ( 2.5V, 100/133MHz) - 8 PCI clocks, including 1 free-running (3.3V, 33MHz) - 1 CPU/2 clocks (2.5V, 50/66MHz) - 1 IOAPIC clocks (2.5V, 16.67MHz) - 3 Fixed frequency 66MHz clocks(3.3V, 66MHz) - 2 REF clocks(3.3V, 14.318MHz) - 1 USB clock (3.3V, 48MHz) Efficient power management through PD#, CPU_STOP# and PCI_STOP#. 0 to -0.5% typical down spread modulation on CPU, PCI, IOAPIC, 3V66 and CPU/2 output clocks. Uses external 14.318MHz crystal. Key Specification • • • • • • • • • • • CPU Output Jitter: <250ps CPU/2 Output Jitter. <250ps IOAPIC Output Jitter: <500ps 48MHz, 3V66, PCI Output Jitter: <500ps Ref Output Jitter. <1000ps CPU Output Skew: <175ps PCI Output Skew: <500ps 3V66 Output Skew <250ps CPU to 3V66 Output Offset: 0.0 - 1.5ns (CPU leads) 3V66 to PCI Output Offset: 1.5 - 4.0ns (3V66 leads) CPU to IOAPIC Output Offset 1.5 - 4.0ns (CPU leads) • • • Block Diagram Pin Configuration 48-pin SSOP 9248-66 Rev - 7/28/99 ADVANCE INFORMATION documents contain information on products in the formative or design phase development. Characteristic data and other specifications are design goals. ICS reserves the right to change or discontinue these products without notice. Advance Information General Description The ICS9248-66 is a main clock synthesizer chip for Pentium II based systems using Rambus Interface DRAMs. This chip provides all the clocks required for such a system when used with a Direct Rambus Clock Generator(DRCG) chip such as the ICS9211-01. Spread Spectrum may be enabled by driving the SPREAD# pin active. Spread spectrum typically reduces system EMI by 8d B to 10d B. This simplifies EMI qualification without resorting to board design iterations or costly shielding. The ICS9248-66 employs a proprietary closed loop design, which tightly controls the percentage of...