Datasheet > CY2278A

CY2278A

更新时间： 2024-11-20 23:44:55

品牌	Logo	应用领域
其他 - ETC		时钟
页数	文件大小	规格书
12页	165K
描述
Clocks and Buffers

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数据手册

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CY2278A 数据手册

CY2278A

Pentium /II Clock Synthesizer/Driver for Mobile PCs

with Intel 82430TX and No SDRAM

voltage applied on pin 42. There are ten PCI clocks, running

at one half the CPU clock frequency. Free-running PCI and

Features

• Mixed 2.5V and 3.3V operation

CPU clocks are available as options shown in the selector

guide. Additionally, the part outputs two 3.3V USB/IR clocks at

48 MHz, one Keyboard clock at 8 MHz, one 2.5V IOAPIC clock

at 14.318 MHz, and two 3.3V reference clocks at 14.318 MHz.

• Complete clock solution to meet requirements of mo-

bile Pentium^®and Pentium^®II motherboards

— Seven CPU clock outputs (three at 3.3V, and four at

2.5Vor3.3V)witheightselectableclockfrequencies.

The CY2278 family contains several features for output flexi-

bility and power control. The CPU, PCI, USB and IR clock

frequencies are all factory EPROM-programmable. Three

hardware select inputs support eight CPU clock frequencies

from 20–75 MHz. Additionally, each of the CPU, PCI, and

USB/IR clock sets can be turned on or off with a dedicated

enable input pin for power management.

— Ten 3.3V synchronous PCI clock outputs

— Two 3.3V USB/IR clocks at 48 MHz

— One Keyboard clock at 8 MHz

— One 2.5V IOAPIC clock at 14.318 MHz

— Two 3.3V Ref. clocks at 14.318 MHz

• Dedicated power management for portable systems

The CY2278A outputs are designed for low EMI emissions.

Controlled rise and fall times, unique output driver circuits and

factory-EPROM programmable output drive and slew-rate en-

able optimal configurations for EMI control.

— Separate output enable pins for CPU, PCI, and

USB/IR clock sets

— Free-running PCI and CPU clocks (see options)

CY2278A Selector Guide

• Factory-EPROM programmable output drive and slew

Clock Outputs

CPU@3.3V

-1L

-2L

-3L

-4L

rate for EMI customization

• Custom configuration with factory-EPROM program-

mable CPU, PCI, and USB/IR frequencies.

• Low skew and low jitter outputs

• Available in space-saving 48-pin TSSOP package

CPU@2.5/3.3V

PCI (CPU/2 MHz)

USB/IR (48 MHz)

KB (8 MHz)

4^[1]

10^[2]

Functional Description

IOAPIC (14.318 MHz)

Ref (14.318 MHz)

CPU-PCI delay

The CY2278A is a Clock Synthesizer/Driver chip for Pentium

or Pentium II portable PCs designed with the 82430TX or sim-

ilar core-logic chipsets. There are four options available as

shown in the selector guide.

0 ns

0 ns 1–5 ns 0 ns

Notes:

The CY2278A outputs seven CPU clocks, three of which run

at 3.3V and four run at either 2.5V or 3.3V, depending on the

1. One free-running CPU clock.

2. Two free-running PCI clocks.

2.5–3.3V Driver

Logic Block Diagram

IOAPIC

14.318 MHz

REF[0-1]

96 MHz

PLL0

OSC.

48 MHz

OUT

USBCLK/IRCLK

CLK8MHz

USB_RUN

8 MHZ

/12

2.5–3.3V Driver

CPUCLK

SEL2

SEL1

SEL0

PLL1

XCPUCLK [0-2]

EPROM

XCPUCLK3_F

on -1L only; not free-

running on -2L, -3L, -4L

CPUCLK [0-2]

CPU_RUN

PCICLK

PCICLK [2-9]

PCICLK_F [0-1]

on -1L, -3L, -4L only; not free-

PCI_RUN

running on -2L

Intel and Pentium are registered trademarks of Intel Corporation.

Cypress Semiconductor Corporation

Document #: 38-07211 Rev. *A

•

3901 North First Street

•

San Jose

•

CA 95134

•

408-943-2600

Revised Decemeber 07, 2002

12 3 4 5 6 7...12

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与CY2278A相关器件

型号	品牌	获取价格	描述	数据表
CY2278APAC-1	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, MOS, PDSO48, TSSOP-48
CY2278APAC-1L	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, CMOS, PDSO48, 6 X 12 MM, TSSOP-48
CY2278APAC-1LT	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, CMOS, PDSO48, 6 X 12 MM, TSSOP-48
CY2278APAC-2	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, MOS, PDSO48, TSSOP-48
CY2278APAC-3	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, MOS, PDSO48, TSSOP-48
CY2278APAC-3L	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, CMOS, PDSO48, 6 X 12 MM, TSSOP-48
CY2278APAC-4	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, MOS, PDSO48, TSSOP-48
CY2278APAC-4L	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, CMOS, PDSO48, 6 X 12 MM, TSSOP-48
CY2278APAC-4LT	CYPRESS	获取价格	Processor Specific Clock Generator, 75MHz, CMOS, PDSO48, 6 X 12 MM, TSSOP-48
CY2278APC-1L	ETC	获取价格	CPU System Clock Generator

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