CY2254ASC-2T

更新时间： 2024-10-14 13:07:11

品牌	Logo	应用领域
赛普拉斯 - CYPRESS		晶体驱动器时钟发生器微控制器和处理器外围集成电路光电二极管
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CY2254ASC-2T 数据手册

CY2254A

Pentium^®Processor Compatible

Clock Synthesizer/Driver

• Freq. stability = 0.01% (max.)

Features

• Output duty cycle 45% min. to 55% max.

• Test mode support (−1 option only)

• 3.3V or 5.0V operation

• Multiple clock outputs to meet requirements of most

Pentium^®motherboards

— Four pin-selectable CPU clocks @ 66.66 MHz, 60.0

MHz, and50.0MHz forsupport ofIntel Triton^™PCIset

based PC

• Internal pull-up resistors on S0, S1, and OE inputs

Functional Description

— 55.0 MHz pin-selectable CPU clock also available (−2

The CY2254A is a Clock Synthesizer/Driver that provides the

multiple clocks required for a Pentium-based PC. The

CY2254A has low-skew outputs (< 250 ps between the CPU

Clocks, < 250 ps between the PCI Clocks). In addition, the

CY2254A CPU clock outputs have less than 200 ps cy-

cle-to-cycle jitter. Finally, both the PCI and CPU clock outputs

meet the 1 V/ns slew rate requirement of a Pentium proces-

sor-based system.

option only)

— Six PCI clocks at 1/2 CPU Clock frequency

— One I/O clock @ 24 MHz

— OneKeyboardControllerclock@ 12MHz(−1 option)

or one Universal Serial Bus clock @ 48 MHz

(−2 option)

— Two Ref. clocks @ 14.318 MHz

The CY2254A accepts a 14.318 MHz reference signal as its

input. The CY2254A has 2 PLLs, one of which generates the

CPU and PCI clocks, and the other generates the I/O and Key-

board Controller or USB clocks. The CY2254A runs off either

a 3.3V or 5V supply.

— Ref. 14.318 MHz Xtal oscillator input

• CPU clock jitter < 200 ps cycle-to-cycle

• Low skew outputs

— < 250 ps between CPU clocks

The CY2254A is available in two options. The −1 option sup-

ports the Intel Triton PCIset and provides a 12 MHz keyboard

clock on pin 25. The −2 option provides a 48 MHz USB clock

on pin 25 and supports the Cyrix^®M1 processor.

— < 250 ps between PCI clocks

— < 500 ps between CPU and PCI clocks (−2 option)

— CPU clock leads PCI clock by +1 ns min. to +4 ns

max. (−1 option)

Pin Configuration

Logic Block Diagram

REF0 (14.318 MHz)

Top View

REF1 (14.318 MHz)

KBDCLK (12 MHz)

SOIC

SYS

÷2

PLL

REF0

REF1

14.318

MHz

OSC.

XTALIN

IOCLK (24 MHz)

XTALOUT

USBCLK (48 MHz)

SEEBELOW

IOCLK

CPUCLK0

CPUCLK1

CPU

PLL

CPUCLK0

CPUCLK1

CPUCLK2

CPUCLK3

PCICLK2

PCICLK3

ROM

CPUCLK2

CPUCLK3

PCICLK4

PCICLK5

÷2

DELAY

PCICLK1

PCICLK0

−1 option only

PCICLK0

PCICLK1

PCICLK2

PCICLK3

PIN 25

OPTION

KBDCLK

12 MHz

USBCLK

48 MHz

−1

−2

PCICLK4

PCICLK5

Intel and Pentium are registered trademarks of Intel Corporation.

Triton is a trademark of Intel Corporation.

Cyrix is a registered trademark of Cyrix Corporation.

Cypress Semiconductor Corporation

Document #: 38-07203 Rev. *A

•

3901 North First Street

•

San Jose

•

CA 95134

•

408-943-2600

Revised December 14, 2002

12 3 4 5 6 7 8

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与CY2254ASC-2T相关器件

型号	品牌	获取价格	描述	数据表
CY2255	ETC	获取价格	CPU System Clock Generator
CY2256PVC-1	ETC	获取价格	CPU System Clock Generator
CY2256SC-1	ETC	获取价格	CPU System Clock Generator
CY2257	ETC	获取价格	CPU System Clock Generator
CY2260PVC-1	CYPRESS	获取价格	Processor Specific Clock Generator, 66.66MHz, MOS, PDSO28, SSOP-28
CY2260PVC-2	CYPRESS	获取价格	Processor Specific Clock Generator, 66.66MHz, MOS, PDSO28, SSOP-28
CY2260PVC-3	CYPRESS	获取价格	Processor Specific Clock Generator, 66.66MHz, MOS, PDSO28, SSOP-28
CY2260SC-1	CYPRESS	获取价格	Processor Specific Clock Generator, 66.66MHz, MOS, PDSO28, 0.300 INCH, PLASTIC, SOIC-28
CY2260SC-1HT	CYPRESS	获取价格	Clock Generator, CMOS, PDSO28
CY2260SC-1T	CYPRESS	获取价格	Clock Generator, CMOS, PDSO28

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