ICS951412 Datasheet, PDF (4/19 Pages) Integrated Circuit Systems – System Clock Chip for ATI RS480 K8-based Systems

ICS951412
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.
Block Diagram
X1
X2
XTAL
OSC.
FIXED PLL
DIVIDER
MAIN PLL
DIVIDERS
REF(2:0)
USB_48MHz
PCICLK0
HTTCLK0
SRCCLK(7:3,0)
ATIGCLK(1:0)
CPUCLK8(1:0)
FS(2:0)
CLKREQA#
CLKREQB#
SEL75#/100
SDATA
SCLK
CONTROL
LOGIC
IREF
Skew Characteristics
Parameter
T_{sk_CPU_CPU}
T_{sk_CPU_PCI}
T_{sk_PCI_PCI}
T_{sk_PCI33-HT66}
T_{sk_CPU_HT66}
T_{sk_CPU_HT66}
T_{sk_CPU_CPU}
T_{sk_CPU_PCI}
T_{sk_PCI_PCI}
T_{sk_PCI33-HT66}
T_{sk_CPU_HT66}
T_{sk_CPU_HT66}
0883G—12/08/04
Description
Test Conditons
time independent
skew
not dependent on
V, T changes
time variant skew
varies over
V, T changes
measured at x-ing of CPU,
measured at x-ing of CPU,
1.5V of PCI clock
measured between rising
edge at 1.5V
measured between rising
edge at 1.5V
measured between rising
edge at 1.5V
measured at x-ing of CPU,
1.5V of PCI clock
measured at x-ing of CPU,
measured at x-ing of CPU,
1.5V of PCI clock
measured between rising
edge at 1.5V
measured between rising
edge at 1.5V
measured between rising
edge at 1.5V
measured at x-ing of CPU,
1.5V of PCI clock
Skew
Window
250
2000
500
500
2000
500
200
200
200
200
200
200
Unit
ps
ps
ps
ps
ps
ps
ps
ps
ps
ps
ps
ps
4