参数资料
型号: 9248DF-39LFT
厂商: INTEGRATED DEVICE TECHNOLOGY INC
元件分类: 时钟产生/分配
英文描述: 150 MHz, PROC SPECIFIC CLOCK GENERATOR, PDSO48
封装: 0.300 INCH, GREEN, SSOP-48
文件页数: 1/18页
文件大小: 321K
代理商: 9248DF-39LFT
Integrated
Circuit
Systems, Inc.
General Description
Features
ICS9248-39
Block Diagram
Pentium is a trademark of Intel Corporation
I
2C is a trademark of Philips Corporation
Frequency Generator & Integrated Buffers for PENTIUM/ProTM
9248-39 Rev F 12/16/99
Pin Configuration
3.3V outputs: SDRAM, PCI, REF, 48/24MHz
2.5V outputs: CPU, IOAPIC
20 ohm CPU clock output impedance
20 ohm PCI clock output impedance
Skew from CPU (earlier) to PCI clock - 1.5 to 4 ns,
center 2.6 ns.
No external load cap for CL=18pF crystals
±175 ps CPU clock skew
250ps (cycle to cycle) CPU jitter
Smooth frequency switch, with selections from 66.8
to 150 MHz CPU.
I
2C interface for programming
3ms power up clock stable time
Clock duty cycle 45-55%.
48 pin 300 mil SSOP package
3.3V operation, 5V tolerant inputs (with series R)
<5ns propagation delay SDRAM from Buffer Input
48-Pin SSOP
Power Groups
VDD1 = REF (0:1), X1, X2
VDD2 = PCICLK_F, PCICLK(0:4)
VDD3 = SDRAM (0:12), supply for PLL core
VDD4 = 24MHz, 48MHz
VDDL1 = IOAPIC
VDDL2 = CPUCLK 1, CPUCLK_F
* Internal Pull-up Resistor of 240K to VDD
** Internal Pull-down resistor of 240K to GND
The ICS9248-39 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.
Features include two CPU, six PCI and thirteen SDRAM
clocks. Two reference outputs are available equal to the crystal
frequency. Plus the IOAPIC output powered by VDDL1. One
48 MHz for USB, and one 24 MHz clock for Super IO. Spread
Spectrum built in at ±0.5% or ±0.25% modulation to reduce
the EMI. Serial programming I
2C interface allows changing
functions, stop clock programing and Frequency selection.
Additionally, the device meets the Pentium power-up
stabilization, which requires that CPU and PCI clocks be
stable within 2ms after power-up. It is not recommended to
use I/O dual function pin for the slots (ISA, PIC, CPU,
DIMM). The add on card might have a pull up or pull down.
High drive PCICLK and SDRAM outputs typically provide
greater than 1 V/ns slew rate into 30pF loads. CPUCLK
outputs typically provide better than 1V/ns slew rate into 20pF
loads while maintaining 50±5% duty cycle. The REF and 24
and 48 MHz clock outputs typically provide better than 0.5V/
ns slew rates into 20pF.
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.
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