Product specifications

VT8237R Data Sheet
Revision 2.06 December 15, 2004 -166- Functional Descriptions
The suspend state is entered by setting the Sleep Enable bit to
1. Three power plane control signals (SUSA#, SUSB# and
SUSC#) are provided to turn off more system power planes as
the system moves to deeper power-down states, i.e., from
normal operation to POS (only SUSA# asserted), to STR (both
SUSA# and SUSB# asserted), and to STD (all three SUS#
signals asserted). In particular, the assertion of SUSC# can be
used to turn off the VCC supply to the VT8237R.
One additional suspend status indicator (SUSST1#) is
provided to inform the north bridge and the rest of the system
of the processor and system suspend states. SUSST1# is
asserted when the system enters the suspend state or the
processor enters the C3 state. SUSST1# is connected to the
north bridge to switch between normal and suspend-DRAM-
refresh modes.
General Purpose I/O Ports
As ACPI compliant hardware, the VT8237R includes
PWRBTN#, SLPBTN#, and RI# pins to implement power
button, sleep button, and ring indicator functionality,
respectively. Furthermore, the VT8237R offers many general-
purpose I/O ports with the following capabilities:
• I
2
C / SMB Support
• Thermal Detect
• Notebook Lid Open / Close Detect
• Battery Low Detect
• Twelve General Purpose Input Ports (multiplexed with
other functions).
• Nineteen General Purpose Output Ports (1 dedicated
and 18 multiplexed with other functions)
• Four General Purpose Input / Output Ports
(multiplexed with other functions)
In addition, the VT8237R provides an external dedicated SMI
pin (EXTSMI#). The external SMI input can be programmed
to trigger an SCI or SMI at both the rising and falling edges of
the corresponding input signal. Software can check the status
of the input pin and take appropriate actions.
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#)