Product specifications

VT8235 V-Link South Bridge
Revision 1.22 October 24, 2002 -134- Functional Descriptions
Power Management Events
Three types of power management events are supported:
1) ACPI-required Fixed Events defined in the PM1a Status
and PM1a Enable registers. These events can trigger
either SCI or SMI depending on the SCI Enable bit:
• PWRBTN# Triggering
• RTC Alarm
• Sleep Button
• ACPI Power Management Timer Carry (always SCI)
• BIOS Release (always SCI)
2) ACPI-aware General Purpose Function Events defined
in the GP Status and GP SCI Enable, and GP SMI Enable
registers. These events can trigger either SCI or SMI
depending on the setting of individual SMI and SCI
enable bits:
• External SMI triggering
• USB Resume
• Ring Indicator (RI#)
• Battery Low Detect (BATLOW#)
• Notebook Lid Open/Close Detect (LID)
• Thermal Detect (THRM#)
3) Generic Global Events defined in the Global Status and
Global Enable registers. These registers are mainly used
for SMI:
• PCI Bus Clock Run Resume
• Primary Interrupt Occurance
• GP0 and GP1 Timer Time Out
• Secondary Event Timer Time Out
• Occurrence of Primary Events
(defined in the Primary Activity Status and Primary
Activity Enable registers)
• Legacy USB accesses (keyboard and mouse)
- Software SMI
System and Processor Resume Events
Depending on the system suspend state, different features can
be enabled to resume the system. There are two classes of
resume events:
a) VSUS-based events. Event logic resides in the
VSUS plane and thus can resume the system from
any suspend state. Such events include PWRBTN#,
RI#, BATLOW#, LID, SMBus resume event, RTC
alarm, EXTSMI#, and GP1 (EXTSMI1#).
b) VCC-Based Events. Event logic resides in the VCC
plane and thus can only resume the system from the
POS state. Such events include the ACPI PM timer,
USB resume, and EXTSMIn#.
Figure 4. System Block Diagram Using the VT8754 North Bridge
HCLK
GCLK
Host CPU
CPU
Bus
CKE#
Memory Bus
SMBus
LPC
VT8754
North
Bridge
(P4X333
Chipset)

DDR
SDRAM
3D
Graphics
Controller
AGP Bus
PCISTP#
GPIO and ACPI Events
BIOS ROM
GCKRUN#
PCI Bus
IDE
USB 2
Power Plane & Peripheral Control
VT8235
South
Bridge
Ke
y
board / Mouse
CPUSTP#
Clock
Generator
MCL
K
HCLK
GCLK
PCLK
SMI# / STPCLK#
SUSCLK,
SUSST1
#
SMIACT#
Module ID
PHY
MII
10 / 100BaseT Lan
AC97
V-Link
Interface
PCKRUN#
PCLK