Product specifications
VT8235 V-Link South Bridge
Revision 1.22 October 24, 2002 -20- Pin Descriptions
Resets, Clocks, and Power Status
Signal Name Pin # I/O Signal Description
PWRGD
AF4 I Power Good. Connected to the Power Good signal on the Power Supply. Internal logic
powered by VBAT.
PWROK#
AE2 O Power OK. Internal logic powered by VSUS33.
PCIRST#
R2 O PCI Reset. Active low reset signal for the PCI bus. The VT8235 will assert this pin
during power-up or from the control register.
OSC
AC12 I Oscillator. 14.31818 MHz clock signal used by the internal Timer.
RTCX1
AD4 I RTC Crystal Input: 32.768 KHz crystal or oscillator input. This input is used for the
internal RTC and power-well power management logic and is powered by VBAT.
RTCX2
AF3 O RTC Crystal Output: 32.768 KHz crystal output. Internal logic powered by VBAT.
TEST
AF9 I
Test.
TPO
U24 O Test Pin Output. Output pin for test mode.
Power and Ground
Signal Name Pin # I/O Signal Description
VCC33
(see pin list) P
I/O Power. 3.3V
±5%
VCC
(see pin list) P
Core Power. 2.5V
±5%. This supply is turned on only when the mechanical switch on
the power supply is turned on and the PWRON signal is conditioned high. Note: The
VT8235L core voltage is 2.5V so board designs that are intended to allow use of either
VT8235 or VT8235L should take this difference into account and allow the core
voltage to be selected as either 2.5V (for the VT8235) or 3.3V (for the VT8235L).
GND
(see pin list) P Ground. Connect to primary motherboard ground plane.
VSUS33
AA4, AB4,
AC4, AC5
P Suspend Power. 3.3V ±5%. Always available unless the mechanical switch of the
power supply is turned off. If the “soft-off” state is not implemented, then this pin can be
connected to VCC33. Signals powered by or referenced to this plane are: PWRGD,
RSMRST#, PWRBTN#, SMBCK1/2, SMBDT1/2, GPO0, SUSA# / GPO1, SUSB# /
GPO2, SUSC#, SUSST1# / GPO3, SUSCLK / GPO4, GPI1, GPI2 / EXTSMI#, GPI3 /
RING#, GPI4 / LID, GPI5 / BATLOW#, GPI6 / PME#, SMBALRT#
VSUS25
T4, U4 P Suspend Power. 2.5V ±5%.
VSUSUSB
D15 P USB Suspend Power. 2.5V ±5%.
VBAT
AE4 P RTC Battery. Battery input for internal RTC (RTCX1, RTCX2)
VLVREF
J23 P V-Link Voltage Reference. 0.9V ±5% for 4x transfers and 0.625V ±5% for 8x transfers.
VCCVK
(see pin list) P
V-Link Compensation Circuit Voltage. 2.5V
±5%
MIIVCC
D11, D12,
E11, E12
P LAN MII Power. 3.3V ±5%.Power for LAN Media Independent Interface (interface to
external PHY). Connect to VCC33 through a ferrite bead.
MIIVCC25
D13, E13 P LAN MII Suspend Power. 2.5V ±5%.
RAMVCC
E7 P LAN RAM Power. 2.5V ±5%. Power for LAN internal RAM. Connect to VCC
through a ferrite bead.
RAMGND
E8 P LAN RAM Ground. Connect to GND through a ferrite bead.
USBVCC
(see pin list) P USB 2.0 Differential Output Power. 3.3V ±5%. Power for USB differential outputs
(USBP0+, P0–, P1+, P1–, P2+, P2–, P3+, P3–, P4+, P4–, P5+, P5–). Connect to VSUS33
through a ferrite bead.
USBGND
(see pin list) P USB 2.0 Differential Output Ground. Connect to GND through a ferrite bead.
VCCUPLL
A23, D22 P USB 2.0 PLL Analog Voltage. 2.5V ±5%. Connect to VCC through a ferrite bead.
GNDUPLL
B23, E22 P USB 2.0 PLL Analog Ground. Connect to GND through a ferrite bead.
PLLVCC
P22 P PLL Analog Power. 2.5V ±5%. Connect to VCC through a ferrite bead.
PLLGND
P23 P PLL Analog Ground. Connect to GND through a ferrite bead.
PDVREF
W22 P IDE Primary Data Channel Voltage Reference. 0.9V†
SDVREF
AD17 P IDE Secondary Data Channel Voltage Reference. 0.9V†
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