ICS9148-53 Datasheet, PDF (1/18 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for Mother Boards

Integrated
Circuit
Systems, Inc.
ICS9148 - 53
Frequency Generator & Integrated Buffers for Mother Boards
General Description
Features
The ICS9148-53 generates all clocks required for high speed
RISC or CISC microprocessor systems such as Intel
•
Generates the following system clocks:
- 3 CPU(2.5V/3.3V) up to 150MHz.
PentiumPro, AMD or Cyrix. Sixteen different reference
- 7 PCI(3.3V) (including one free
frequency multiplying factors are externally selectable with
running PCICLK)
smooth frequency transitions.
- 2AGP(3.3V) @ 2 x PCI
- 13 SDRAMs(3.3V) up to 150MHz
Spread spectrum may be enabled through I2C programming.
- 1 REF (3.3V) @ 14.318MHz
- 1 Fixed clock 3.3V @ 48MHz
Spread spectrum typically reduces system EMI by 8dB to
10dB. This simplifies EMI qualification without resorting to • Skew characteristics:
board design iterations or costly shielding. The ICS9148-53
employs a proprietary closed loop design, which tightly
- CPU – CPU<250ps
- CPU(early) – PCI : 1-4ns
controls the percentage of spreading over process and _{• Supports Spread Spectrum modulation & I}²_C
temperature variations.
programming for Power Management, Frequency Select
Serial programming I²C interface allows changing functions,
•
Efficient Power management scheme through power
down CPU, PCI, AGP and CPU_STOP clocks.
stop clock programming and frequency selection. The
SDRAM12 output may be used as a feed back into an off chip • Uses external 14.318MHz crystal
PLL.
Block Diagram
• 48 pin 300mil SSOP.
• Read back of FS pin values from I²C
Pin Configuration
Power Groups
VDD1 = REF (0:1), X1, X2
VDD2 = PCICLK_F, PCICLK(0:5)
VDD3 = SDRAM (0:12), supply for PLL core
VDD4 = AGP (1:2)
VDD5 = Fixed PLL, 48MHz , AGP0
VDDL = CPUCLK (0:3)
9148-53 Rev C 08/14/98
48-Pin SSOP
* Internal Pull-up Resistor of
240K to 3.3V on indicated inputs
Pentium is a trademark of Intel Corporation
I²C is a trademark of Philips Corporation
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.