4

ICS9150- 01

VDD(1,2,3)

Thisisthepowersupplytotheinternalcorelogicofthedeviceaswell

as the clock output buffers for REF(0:1), PCICLK, and

SDRAM(0:7).

This pin operates at 3.3V volts. Clocks from the listed buffers that it

supplies will have a voltage swing from Ground to this level. For the

actual guaranteed high and low voltage levels for the Clocks, please

consult the DC parameter table in this data sheet.

VDDL1,2

This is the power supplies for the CPUCLK and IOAPCI output

buffers. The voltage level for these outputs may be 2.5 or 3.3volts.

Clocks from the buffers that each supplies will have a voltage swing

from Ground to this level. For the actual Guaranteed high and low

voltage levels of these Clocks, please consult the DC parameter

table in this Data Sheet.

GND

This is the power supply ground (common or negative) return pin for

the internal core logic and all the output buffers.

X1

This input pin serves one of two functions. When the device is used

with a Crystal, X1 acts as the input pin for the reference signal that

comes from the discrete crystal. When the device is driven by an

external clock signal, X1 is the device input pin for that reference

clock. ThispinalsoimplementsaninternalCrystalloadingcapacitor

that is connected to ground. See the data tables for the value of this

capacitor.

X2

This Output pin is used only when the device uses a Crystal as the

reference frequency source. In this mode of operation, X2 is an

output signal that drives (or excites) the discrete Crystal. The X2 pin

will also implement an internal Crystal loading capacitor that is

connected to ground. See the Data Sheet for the value of this

capacitor.

CPUCLK (0:4)

These Output pins are the Clock Outputs that drive processor and

other CPU related circuitry that requires clocks which are in tight

skew tolerance with the CPU clock. The voltage swing of these

Clocks are controlled by theVoltage level applied to theVDDL2 pin

of the device. See the Functionality Table for a list of the specific

frequencies that are available for these Clocks and the selection

codes to produce them.

SDRAM(0:15)

These Output Clocks are use to drive Dynamic RAM’s and are low

skew copies of the CPU Clocks. The voltage swing of the

SDRAM’s output is controlled by the supply voltage that is applied

to VDD3 of the device, operates at 3.3 volts.

IOAPIC (0:2)

These Outputs are fixed frequency Output Clocks that run at the

Reference Input (typically 14.31818MHz) . Its voltage level swing

is controlled by VDDL1 and may operate at 2.5 or 3.3volts.

Technical Pin Function Descriptions

REF0

The REF Output is a fixed frequency Clock that runs at the same

frequency as the Input Reference Clock X1 or the Crystal (typically

14.31818MHz) attached across X1 and X2.

PCICLK_F

This Output is equal to PCICLK(0:5) and is FREE RUNNING, and

will not be stopped by PCI_STP#.

PCICLK (0:5)

These Output Clocks generate all the PCI timing requirements for a

Pentium/Pro based system. They conform to the current PCI

specification. They run at 1/2 CPU frequency.

FS0

This Input pin controls the frequency of the Clocks at the CPU,

PCICLK and SDRAM output pins. If a logic “1” value is present on

this pin, the 66.6 MHz Clock will be selected. If a logic “0” is used,

the60MHzfrequencywillbeselected.(ThisisthePowerManagement

Mode)

MODE

This Input pin is used to select the Input function of the

I/O pins.

An active Low will place the I/O pins in the Input mode and enable

those stop clock functions. (This is the Power Management Mode)

CPU_STOP#

This is a synchronous active Low Input pin used to stop the CPUCLK

clocks in an active low state. All other Clocks including SDRAM

clocks will continue to run while this function is enabled. The

CPUCLK’s will have a turn ON latency of at least 3 CPU clocks. This

input pin only valid when MODE=0 (Power Management Mode)

PCI_STOP#

This is a synchronous active Low Input pin used to stop the PCICLK

clocks in an active low state. It will not effect PCICLK_F nor any

other outputs. This input pin only valid when MODE=0 (Power

Management Mode)

The SDATAand SCLOCK Inputs are use to program the device. The

allow read-back of the registers. See configuration map for register

Handbook (1996) should be followed.