82801BA Datasheet, PDF (61/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

System Clock Domains
System Clock Domains
4
Table 4-1 shows the system clock domains. Figure 4-2 shows the assumed connection of the
various system components, including the clock generator. For complete details of the system
clocking solution, refer to the system’s clock generator component specification.
Figure 4-1. ICH2 and System Clock Domains
Clock
Domain
ICH2
CLK66
Frequency
66 MHz
ICH2
PCICLK
33 MHz
System PCI
33 MHz
ICH2
CLK48
48 MHz
ICH2
CLK14
14.31818 MHz
ICH2
AC_BIT_CLK
12.288 MHz
RTC
32.768 kHz
ICH2
APICCLK
33.33 MHz
LAN_CLK 0.8 to 50 MHz
Source
Main Clock
Generator
Main Clock
Generator
Main Clock
Generator
Main Clock
Generator
Main Clock
Generator
AC’97 Codec
ICH2
Main Clock
Generator
LAN Connect
Component
Usage
Hub interface, processor interface. AGP.
82801BA ICH2: It is shut off during S3 or below.
82801BAM ICH2-M: It is shut off during S1 or below.
Free-running PCI Clock to ICH2/ICH2-M.
82801BA ICH2: This clock remains on during S0 and S1
state, and is expected to be shut off during S3 or below.
82801BAM ICH2-M: This clock remains on during S0
state, and is expected to be shut off during S1 or below.
PCI Bus, LPC I/F. These only go to external PCI and
LPC devices.
82801BAM ICH2-M: These will stop based on CLKRUN#
(and STP_PCI#)
Super I/O, USB Controller.
82801BA ICH2: Expected to be shut off during S3 or
below.
82801BAM ICH2-M: Expected to be shut off during S1
or below.
Used for ACPI timer.
82801BA ICH2: Expected to be shut off during S3 or
below.
82801BAM ICH2-M: Expected to be shut off during S1 or
below.
AC’97 Link. Generated by AC’97 CODEC. Can be shut
off by codec in D3.
82801BA ICH2: Expected to be shut off during S3 or
below.
82801BAM ICH2-M: Expected to be shut off during S1 or
below.
RTC, Power Management. ICH2 has its own oscillator.
Always running, even in G3 state.
Used for ICH2/ICH2-M processor interrupt messages.
Runs at 33.33 MHz.
82801BA ICH2: Expected to be shut off during S3 or
below.
82801BAM ICH2-M: Expected to be shut off during S1 or
below.
Generated by the LAN Connect component.
82801BA ICH2: Expected to be shut off during S3 or
below.
82801BAM ICH2-M: Expected to be shut off during S1 or
below.
82801BA ICH2 and 82801BAM ICH2-M Datasheet
4-1