PRELIMINARY
C9641
133 MHz Clock Generator for ALI 1641 Chipset Systems
Power Management Functions (Cont.)
When AGP_STP# is forced low, both AGP clocks are synchronously disabled in a low state. These signals will
complete one full cycle before stopping one the following falling edge When AGP_STP# is released to high, AGP clocks
are synchronously re-enabled after one full PCI_F cycle latency.
When PWR_DN# is forced low, CPU(0:1), PCI(F,1:5), IOAPIC, SDRAM(0:12), 48_24#MHz, and REF(0:1) signals are
synchronously disabled, all internal circuitry (including the crystal buffer) is shutdown and the device is then placed in
Low Power (or in power down) Mode. After PWR_DN# is forced low, all power supplies (3.3V and 2.5V) may be
removed. All power supplies must be re-applied 200mS before releasing PWR_DN# (to high), consequently, the device
must be allowed 1mS before the clock outputs settle to their preset frequencies. (see Fig.4, and table 2 below)
Power Management Timing
Tss
Tss
PCI_F
PCI_STP
PCI(0:5)
CPU_STP
CPU(0:1)
AGP_STP
AGP(1:0)
Fig. 4
Tss is the stop clock setup time. All functionality is referenced to the rising edge of PCI_F. If the tss timing is met, with
respect to the next occurring PCI_F low to high transition, then the CPU or PCI clocks that are controlled are guaranteed
to stay low (stopped) or to rise (run) at the next rising edge of PCI_F. See the AC parameters for tss time.
Power Management Function Table
AGP_
STP#
CPU_
STP#
PWR_
DN#
PCI_
SDRAM
(0:12)
CPU
(0:1)
REF
(0:1)
PCI
(1:5)
PCI_F
48_24M
IOAPIC
PLL1
PLL2
AGP
(0:1)
STP#
X
1
1
1
1
0
0
0
0
X
0
0
1
1
1
0
1
0
0
1
1
1
1
1
1
1
1
X
0
1
0
1
1
1
0
0
LOW
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
LOW
LOW
LOW
RUN
RUN
RUN
LOW
RUN
LOW
LOW
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
LOW
LOW
RUN
LOW
RUN
RUN
RUN
LOW
LOW
LOW
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
LOW
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
LOW
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
OFF
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
OFF
RUN
RUN
RUN
RUN
RUN
RUN
RUN
RUN
LOW
RUN
RUN
RUN
RUN
OFF
OFF
OFF
OFF
Table 2
Cypress Semiconductor Corporation
525 Los Coches St.
Document#: 38-07037 Rev. **
5/02/2001
Milpitas, CA 95035. Tel: 408-263-6300, Fax: 408-263-6571
http://www.cypress.com
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