IDTTM

Progammable Timing Control HubTM for Next Gen P4TM Processor

701J—01/25/10

ICS952601

Programmable Timing Control HubTM for Next Gen P4TM Processor

20

CPU_Stop = Driven, CPU_Pwrdwn = Tristate

CPU_Stop#

1.8mS

PWRDWN#

CPU (Free Running)

CPU# (Free Running)

CPU (Stoppable)

CPU# (Stoppable)

Notes:

1. When CPU_Pwrdwn is set to tristate and CPU_Stop is set to driven, the clock chip will tristate outputs only during the

assertion of PWRDWN#. Differential clock behavior during the assertion/de-assertion of CPU_Stop# will be unaffected.

2. In the case that CPU_Stop# is de-asserted during the 1.8mS PWRDWN# de-assertion resume delay, the clock chip can

sample the CPU_Stop# high with the internal rising edges of clock#. This will result in CPU clocks resuming immediately

after the 1.8mS windows expires. This applies to all control register bit changes as well.

3. Tristate outputs are pulled low by output termination resistors as shown here.

CPU_Stop = Tristate, CPU_Pwrdwn = Tristate

CPU_Stop#

1.8mS

PWRDWN#

CPU (Free Running)

CPU# (Free Running)

CPU (Stoppable)

CPU# (Stoppable)

Notes:

1. When CPU_Stop and CPU_Pwrdwn bits are set to tristate, the clock chip will tristate the outputs during the assertion of

CPU_Stop# and PWRDWN#.

2. Tristate outputs are pulled low by output termination resistors as shown here.