ICS9148-13 Datasheet, PDF (1/7 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for PENTIUMTM

Integrated
Circuit
Systems, Inc.
ICS9148 - 13
Frequency Generator & Integrated Buffers for PENTIUM^TM
General Description
The ICS9148-13 generates all clocks required for high speed
RISC or CISC microprocessor systems such as Intel Pentium
and PentiumPro. An output enable is provided for testability.
Spread Spectrum is available to modulate the CPU and BUS
PLL (leaving the REF, 24, 48 MHz operating normally). The
SS_EN# pin enables the spreading when low. The SS_TYPE
pin choses ±0.5% (nominally) center spread or +0, -2%
(nominally) downspread modulation.
High drive BUS outputs typically provide greater than 1V/ns
slew rate into 30 pF loads. CPU outputs typically provide
better than 1V/ns slew rate into 20 pF loads while maintaining
50 ±5% duty cycle. The REF clock outputs typically provide
better than 0.8/ns slew rates.
Block Diagram
Features
• Generates twelve processor, six bus, two
14.31818MHz, 24MHz and one 48MHz clock for
USB support.
• Synchronous clocks skew matched to 250 ps window
on CPUs and 500 ps window on BUSs
• CPU to BUS skew, 3.0 to 5.0ns (CPU Early)
• 3.0V - 3.7V supply range
• 48-pin SSOP package
Pin Configuration
48-Pin SSOP
Output Enable
OE
REF
24 48
(MHz) (MHz)
CPU
BUS
VCO
OSC
1 Runs Runs Runs Runs Runs Runs Runs
0
Tri-
state
Tri-
state
Tri-
state
Tri-
state
Tri-
state
Runs
Runs
30K pullup resistor to VDD on OE, FS(0:2), SS_EN#, SS_TYPE
Functionality
FS2 FS1 FS0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
CPU (1:12) in
MHz
75
100
75
83.3
50
60
66.67
55
BUS (1:6) in
MHz
37.5
33.3
30.0
41.65
25
30
33.33
27.5
Pentium is a trademark of Intel Corporation
9148-13 Rev A 020398
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.