ics9248-55 Integrated Device Technology, ics9248-55 Datasheet - Page 2

• Manufacturer Part Number: ics9248-55
• Description: Pentium/pro/iitm System Clock Chip
• Manufacturer: Integrated Device Technology

ICS9248-55
Pin Descriptions
8, 10, 11, 13, 14, 16, 17
FS2
Spread Spectrum
0
0
0
0
1
1
1
1
Functionality
PIN NUMBER
35, 36, 39, 40
Testmode
Tristate
25, 26, 27
6, 12, 18
20, 32
44, 45
19, 33
22, 23
37, 41
34, 38
9, 15
1, 2
FS1
42
21
24
28
29
30
31
43
46
47
48
3
4
5
7
0
0
0
0
1
1
1
1
FS0
0
0
0
0
1
1
1
1
Modulated
TCLK/2
HI - Z
CPU
CPUCLK (3:0)
CPU MHz
PCICLK (0:6)
IOAPIC (0:1)
CPU_STOP#
48MHz (0:1)
REF0, REF1
PIN NAME
PCI_STOP#
PCICLK_F
SPREAD#
1
SS_SEL
FS (0:2)
VDDL2
GNDL2
GNDL1
VDDL1
2
83.3
66.6
124
112
100
133
133
GND1
GND2
VDD2
VDD3
GND3
VDD1
75
REF2
VDD
GND
PD#
N/C
X2
X1
Modulated
TCLK/6
PCI_F
HI - Z
PCI,
1
2
PCI MHz
14.318MHz
33.25
41.65
41.33
37.5
33.3
44.3
37.3
33.3
TCLK
HI - Z
TYPE
REF
PWR
PWR
PWR
PWR
PWR
PWR
PWR
PWR
PWR
PWR
PWR
PWR
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
IN
IN
IN
IN
IN
IN
IN
-
1
14.318MHz
IOAPIC
14.318MHz clock output
14.318MHz clock output
Ground for REF outputs
load cap and feed back resistor from X2
Ground for PCI outputs
Power for PCICLK outputs, nominally 3.3V
Isolated power for core, nominally 3.3V
Isolated ground for core
Power for 48MHz outputs, nominally 3.3V
Ground for 48MHz outputs
Powers down chip, active low
Halts CPU clocks at logic "0" level when low
Halts PCI Bus at logic "0" level when low
Power for CPU outputs, nominally 2.5V
Ground for CPU outputs.
CPU and Host clock outputs @ 2.5V
Ground for IOAPIC outputs
IOAPIC outputs (14.318MHz) @ 2.5V
Power for IOAPIC outputs, nominally 2.5V
±.25% Spread Spectrum Selector at power up.
Supply for REF (0:2), X1, X2, nominal 3.3V
TCLK
XTAL_IN 14.318MHz Crystal input, has internal 33pF
XTAL_OUT Crystal output, has internal load cap 33pF
Free Running PCI output
PCI clock outputs. TTL compatible 3.3V
48MHz outputs
Frequency Select pins
Enables Spread Spectrum feature when LOW
Not internally connected
Logic 0 for Downspread
Logic 1 for Centerspread
HI - Z
1
Selection
48.0MHz
TCLK/2
48 MHz
HI - Z
1
DESCRIPTION