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ICS9250BF-12T

P1-P3P4-P6P7-P9P10-P12
4
ICS9250-12
Power Management Requirements:
Note:
1. Clock on/off latency is defined in the number of rising edges of free running PCICLKs between the clock disable goes low/
high to the first valid clock comes out of the device.
2. Power up latency is when PWR_DWN# goes inactive (high to when the first valid clocks are dirven from the device.
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CPU_STOP# Timing Diagram
CPU_STOP# is an asynchronous input to the clock synthesizer. It is used to turn off the CPU and 3V66 clocks for low power
operation. CPU_STOP# is asserted asynchronously by the external clock control logic with the rising edge of free running PCI
clock (and hence CPU clock) and must be internally synchronized to the external output. All other clocks will continue to run
while the CPU clocks are disabled. The CPU clocks must always be stopped in a low state and started in such a manner as to
guarantee that the high pulse width is a full pulse. ONLY one rising edge of PCICLK_F is allowed after the clock control logic
switched for both the CPU and 3V66 outputs to become enabled/disabled.
Notes:
1. All timing is referenced to the internal CPUCLK.
2. The internal label means inside the chip and is a reference only. This
in fact may not be the way that the control is designed.
3. CPU_STOP# signal is an input singal that must be made synchronous
to free running PCICLK_F
4. 3V66 clocks also stop/start before
5. PD# and PCI_STOP# are shown in a high state.
6. Diagrams shown with respect to 133MHz. Similar operation when CPU
is 100MHz
5
ICS9250-12
PCI_STOP# Timing Diagram
PCI_STOP# is an input to the clock synthesizer and must be made synchronous to the clock driver PCICLK_F output. It is used
to turn off the PCI clocks for low power operation. PCI clocks are required to be stopped in a low state and started such that a
full high pulse width is guaranteed. ONLY one rising edge of PCICLK_F is allowed after the clock control logic switched for the
PCI outputs to become enabled/disabled.
Notes:
1. All timing is referenced to CPUCLK.
2. PCI_STOP# signal is an input signal which must be made synchronous to PCICLK_F output.
3. Internal means inside the chip.
4. All other clocks continue to run undisturbed.
5. PD# and CPU_STOP# are shown in a high state.
6. Diagrams shown with respect to 133MHz. Similar operation when CPU is 100MHz.
6
ICS9250-12
PD# Timing Diagram
The power down selection is used to put the part into a very low power state without turning off the power to the part. PD# is
an asynchronous active low input. This signal needs to be synchronized internal to the device prior to powering down the clock
synthesizer.
Internal clocks are not running after the device is put in power down. When PD# is active low all clocks need to be driven to a
low value and held prior to turning off the VCOs and crystal. The power up latency needs to be less than 3 mS. The power down
latency should be as short as possible but conforming to the sequence requirements shown below. PCI_STOP# and CPU_STOP#
are considered to be don't cares during the power down operations. The REF and 48MHz clocks are expected to be stopped in
the LOW state as soon as possible. Due to the state of the internal logic, stopping and holding the REF clock outputs in the
LOW state may require more than one clock cycle to complete.
Notes:
1. All timing is referenced to the Internal CPUCLK (defined as inside the ICS9250 device).
2. As shown, the outputs Stop Low on the next falling edge after PD# goes low.
3. PD# is an asynchronous input and metastable conditions may exist. This signal is synchronized inside this part.
4. The shaded sections on the VCO and the Crystal signals indicate an active clock.
5. Diagrams shown with respect to 133MHz. Similar operation when CPU is 100MHz.
P1-P3P4-P6P7-P9P10-P12

ICS9250BF-12T

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Buy ICS9250BF-12T
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Description:
IC FREQ TIMING GENERATOR 56-SSOP
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