ICS9148-36 Datasheet, PDF (1/16 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for PENTIUM/ProTM

Integrated
Circuit
Systems, Inc.
ICS9148 - 36
Frequency Generator & Integrated Buffers for PENTIUM/Pro^TM
General Description
The ICS9148-36 generates all clocks required for high speed
RISC or CISC microprocessor systems such as Intel PentiumPro
or Cyrix. Eight different reference frequency multiplying factors
are externally selectable with smooth frequency transitions.
Spread spectrum may be enabled through I2C programming.
Spread spectrum typically reduces system EMI by 8dB to
10dB. This simplifies EMI qualification without resorting to
board design iterations or costly shielding. The ICS9148-36
employs a proprietary closed loop design, which tightly
controls the percentage of spreading over process and
temperature variations.
Serial programming I²C interface allows changing functions,
stop clock programming and frequency selection. The
SDRAM12 output may be used as a feed back into an off chip
PLL.
Features
• Generates the following system clocks:
- 3 CPU(2.5V/3.3V) upto 100MHz.
- 6 PCI(3.3V) @ 33.3MHz
- 3AGP(3.3V) @ 2 x PCI
- 13 SDRAMs(3.3V) up to 100MHz
- 1 REF (3.3V) @ 14.318MHz
• Skew characteristics:
- CPU – CPU<250ps
- CPU(early) – PCI : 1-4ns, Center 2-6ns
- AGP - PCI: 250ps
• Supports Spread Spectrum modulation & I²C
programming for Power Management, Frequency Select
• Efficient Power management scheme through PCI and
CPU STOP CLOCKS.
• Uses external 14.318MHz crystal
• 48 pin 300mil SSOP.
Block Diagram
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 (0:2)
9148-36 Rev I 11/11/99
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.