ICS9148-20

Features:

Generates system clocks for CPU, IOAPIC, PCI, plus 14.314 MHz REF (0:2), USB, and Super I/O
Supports single or dual processor systems
Supports Spread Spectrum modulation for CPU & PCI clocks, down spread -0.5%
Skew from CPU (earlier) to PCI clock (rising edges for 100/33.3MHz) 1.5 to 4ns
Two fixed outputs at 48MHz.
Separate 2.5V and 3.3V supply pins
2.5V or 3.3V output: CPU, IOAPIC
3.3V outputs: PCI, REF, 48MHz
No power supply sequence requirements
Uses external 14.318MHz crystal, no external load cap required for CL=18pF crystal
48 pin 300 mil SSOP



Pinout




Specifications

Supply Voltage . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .  . . . . . . . 7.0 V
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . .  . . . . . . GND -0.5 V to V_DD +0.5 V
Ambient Operating Temperature . . . . . . .  . . . . . . . . . . . . . . 0°C to +70°C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . .  . . . . -65°C to +150°C

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These ratings are stress specifications only and functional operation of the device at these or any other conditions above those listed in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect product reliability.


Description

The ICS9148-20 is a Clock Synthesizer chip for Pentium and PentiumPro CPU based Desktop/Notebook systems that will provide all necessary clock timing.

Features include four CPU and eight PCI clocks. Three reference outputs are available equal to the crystal frequen-cy. Additionally, the device meets the Pentium power-up stabilization requirement, assuring that CPU and PCI cloc-ks are stable within 2ms after power-up.

PD# pin enables low power mode by stopping crystal OSC and PLL stages. Other power management features include CPU_STOP#, which stops CPU (0:3) clocks, and PCI_STOP#, which stops PCICLK (0:6) clocks.

High drive CPUCLK outputs of the ICS9148-20 typically provide greater than 1V/ns slew rate into 20pF loads. PCICLK outputs typically
provide better than 1V/ns slew rate into 30pF loads while maintaining 50±5% duty cycle. The REF clock outputs
typically provide better than 0.5V/ns slew rates.

The ICS9148-20 accepts a 14.318MHz reference crystal or clock as its input and runs on a 3.3V core supply.