4

ICS951412

0883G—12/08/04

General Description

The ICS951412 is a main clock synthesizer chip that provides all clocks required for ATI RS480-based systems.

An SMBus interface allows full control of the device.

Skew Characteristics

Parameter

Description

Test Conditons

Skew

Window

Unit

measured at x-ing of CPU,

250

ps

measured at x-ing of CPU,

1.5V of PCI clock

2000

ps

measured between rising

edge at 1.5V

500

ps

measured between rising

edge at 1.5V

500

ps

measured between rising

edge at 1.5V

2000

ps

measured at x-ing of CPU,

1.5V of PCI clock

500

ps

measured at x-ing of CPU,

200

ps

measured at x-ing of CPU,

1.5V of PCI clock

200

ps

measured between rising

edge at 1.5V

200

ps

measured between rising

edge at 1.5V

200

ps

measured between rising

edge at 1.5V

200

ps

measured at x-ing of CPU,

1.5V of PCI clock

200

ps

time independent

skew

not dependent on

V, T changes

time variant skew

varies over

V, T changes

Block Diagram

MAIN PLL

PCICLK0

CONTROL

LOGIC

XTAL

OSC.

CPUCLK8(1:0)

FIXED PLL

USB_48MHz

DIVIDER

DIVIDERS

REF(2:0)

HTTCLK0

SRCCLK(7:3,0)

CLKREQA#

SDATA

SCLK

FS(2:0)

CLKREQB#

SEL75#/100

X1

X2

IREF

ATIGCLK(1:0)