Integrated
Circuit
Systems, Inc.
General Description
Features
Strong output drive.
Eight selectable CPU clocks operate up to 83.3 MHz
Frequency selections include Turbo-mode speed of 68.5
MHz
Maximum CPU jitter of ±200ps
Six BUS clocks support sync or async bus operation
250ps skew window for CPU outputs, 500ps skew window for
BUS outputs
CPU clocks to BUS clocks skew 1-4 ns (CPU early)
48 MHz clock for USB support & 24 MHz clock for FD.
Logic inputs latched at Power-On for frequency selection
saving pins as Input/Output
Integrated buffer outputs drive up to 30pF loads
3.0V - 3.7V supply range, CPU (1:6) outputs 2.5V
(2.375 - 2.6V) VDD option
28-pin SOIC or SSOP package
ICS9169C-232
Block Diagram
Frequency Generator for Pentium Based Systems
9169C-232RevB031897
Pin Configuration
28-Pin SOIC or SSOP
Functionality
3.3V±10%, 0-70
°
C
Crystal (X1, X2) = 14.31818 MHz
Pentium is a trademark of Intel Corporation.
The
ICS9169C-232
is a low-cost frequency generator
designed specifically for Pentium and Pentium-Pro based
chip set systems. The integrated buffer minimizes skew
and provides all the clocks required. A 14.318 MHz XTAL
oscillator provides the reference clock to generate standard
Pentium frequencies. The CPU clock makes gradual
frequency transitions without violating the PLL timing of
internal microprocessor clock multipliers. A raised
frequency setting of 68.5 MHz is available for Turbo-mode
of the 66.8 MHz CPU. The
ICS9169C-232
contains 8 CPU
clocks, 6 PCI clocks, 1 REF at 48MHz and 1 at 24MHz.
Either synchronous (CPU/2) or asynchronous (32 MHz)
PCI bus operation can be selected by latching data on
BSEL input.
ADDRESS
SELECT
FS2 FS1
0
0
0
0
1
1
1
1
CPU(1:8)
(MHz)
BUS (1:6)MHz
48MHz 24MHz
REF
FS0
0
1
0
1
0
1
0
1
BSEL=1 BSEL=0
25
30
33.4
32
27.5
37.5
41.7
34.25
0
0
1
1
0
0
1
1
50
60
66.8
75.9
55
75.9
83.3
68.5
32
32
32
32
32
32
32
32
48
48
48
48
48
48
48
48
24
24
24
24
24
24
24
24
REF
REF
REF
REF
REF
REF
REF
REF
VDD Groups:
VDD1 = X1, X2, REF/BSEL
VDD2 = CPU1-6
VDD3 = CPU7-8 & PLL Core
VDD4 = BUS1-6
VDD5 = 48/24 MHz
Latched Inputs:
L1 = BSEL
L2 = FS0
L3 = FS1
L4 = FS2
ICS reserves the right to make changes in the device data identified in this
publication without further notice. ICS advises its customers to obtain the latest
version of all device data to verify that any information being relied upon by the
customer is current and accurate.