ICS9250-08 Datasheet, PDF (9/15 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for Celeron & PII/III™

ICS9250-08
CPU_STOP# Timing Diagram
CPUSTOP# is an asychronous input to the clock synthesizer. It is used to turn off the CPUCLKs for low power operation.
CPU_STOP# is synchronized by the ICS9250-08. All other clocks will continue to run while the CPUCLKs are disabled. The
CPUCLKs will always be stopped in a low state and start in such a manner that guarantees the high pulse width is a full pulse.
CPUCLK on latency is less than 4 CPUCLKs and CPUCLK off latency is less than 4 CPUCLKs.
Notes:
1. All timing is referenced to the internal CPUCLK.
2. CPU_STOP# is an asynchronous input and metastable conditions may exist. This signal is synchronized to the
CPUCLKs inside the ICS9250-08.
3. IOAPIC output is stopped Glitch Free by CPUSTOP# going low.
4. PCI_STOP# is shown in a high (true) state.
5. All other clocks continue to run undisturbed.
PCI_STOP# Timing Diagram
PCI_STOP# is an asynchronous input to the ICS9250-08. It is used to turn off the PCICLK (0:5) clocks for low power operation.
PCI_STOP# is synchronized by the ICS9250-08 internally. PCICLK (0:5) clocks are stopped in a low state and started with a full
high pulse width guaranteed. PCICLK (0:5) clock on latency cycles are only one rising PCICLK clock off latency is one PCICLK
clock.
Notes:
1. All timing is referenced to the Internal CPUCLK (defined as inside the device.)
2. PCI_STOP# is an asynchronous input, and metastable conditions may exist. This signal is required to be synchronized
inside the device.
3. All other clocks continue to run undisturbed.
4. CPU_STOP# is shown in a high (true) state.
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