AV9248F-131 参数 Datasheet PDF下载

ICS9248-131

General Description

The

ICS9248-131

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 I

2

C 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

ICS9248-131

employs a

proprietary closed loop design, which tightly controls the percentage of spreading over process and temperature variations.

Serial programming I

2

C 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.

Mode Pin - Power Management Input Control

MODE, Pin 25

(Latched Input)

0

1

Pin 17

CPU_STOP#

(INPUT)

SDRAM 11

(OUTPUT)

Pin 18

PCI_STOP#

(INPUT)

SDRAM 10

(OUTPUT)

Pin 20

AGP_STOP#

(INPUT)

SDRAM 9

(OUTPUT)

Pin 21

PD#

(INPUT)

SDRAM 8

(OUTPUT)

Power Management Functionality

AGP_STOP# CPU_STOP# PCI_STOP#

1

1

1

0

0

1

1

1

1

1

0

1

AGP,

CPUCLK

Outputs

Stopped Low

Running

Running

Running

PCICLK

(4:0)

Running

Running

Stopped Low

Running

PCICLK_F,

REF, 48MHz

and SDRAM

Running

Running

Running

Running

Crystal

OSC

Running

Running

Running

Running

VCO

Running

Running

Running

Running

AGP

(1:0)

Running

Running

Running

Stopped Low

CPU 3.3#_2.5V Buffer selector for CPUCLK drivers.

CPU3.3#_2.5

Input level

(Latched Data)

1

0

Buffer Selected for

operation at:

2.5V VDD

3.3V VDD

3