Datasheet > FS781/82/84

FS781/82/84

更新时间： 2024-11-01 23:52:55

品牌	Logo	应用领域
其他 - ETC		时钟
页数	文件大小	规格书
11页	165K
描述
Clocks and Buffers

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FS781/82/84 数据手册

FS781/82/84

Low EMI Spectrum Spread Clock

Features

Description

• Spread Spectrum clock generator (SSCG) with 1×, 2×,

and 4× outputs

• 6- to 82-MHz operating frequency range

• Modulates external clocks including crystals, crystal

oscillators, or ceramic resonators

• Programmable modulation with simple R-C external

loop filter (LF)

• Center spread modulation

• 3V-5V power supply

• TTL-/CMOS-compatible outputs

• Low short-term jitter

The Cypress FS781/82/84 are Spread Spectrum clock

generator ICs (SSCG) designed for the purpose of reducing

electromagnetic interference (EMI) found in today’s

high-speed digital systems.

The FS781/82/84 SSCG clocks use a Cypress-proprietary

technology to modulate the input clock frequency, XIN, by

modulating the frequency of the digital clock. By modulating

the reference clock the measured EMI at the fundamental and

harmonic frequencies of FSOUT is greatly reduced. This

reduction in radiated energy can significantly reduce the cost

of complying with regulatory requirements without degrading

digital waveforms.

• Low-power Dissipation

— 3.3 VDC = 37 mW – typical

The Cypress FS781/82/84 clocks are very simple and

versatile devices to use. By programming the two range select

lines, S0 and S1, any frequency from 6- to 82-MHz operating

range can be selected. The FS781/2/4 are designed to

operate over a very wide range of input frequencies and

provides 1×, 2×, and 4× modulated clock outputs.

— 5.0 VDC = 115 mW – typical

• Available in 8-pin SOIC and TSSOP packages

Applications

The FS78x devices have a simple frequency selection table

that allows operation from 6 MHz to 82 MHz in four separate

ranges. The bandwidth of the frequency spread at FSOUT is

determined by the values of the loop filter components. The

modulation rate is determined internally by the input frequency

and the selected input frequency range.

• Desktop/notebook computers

• Printers, copiers, and MFP

• Scanners and fax

• LCD displays and monitors

• CD-ROM, VCD, and DVD

• Automotive and embedded systems

• Networking, LAN/WAN

The Bandwidth of these products can be programmed from as

little as 1.0% up to as much as 4.0% by selecting the proper

loop filter value. Refer to the Loop Filter Selection chart in

Table 2 and Table 3 for the recommended values. Due to a

wide range of application requirements, an external loop filter

(LF) is used on the FS78x products. The user can select the

exact amount of frequency modulation suitable for the appli-

cation. Using a fixed internal loop filter would severely limit

the use of a wide range of modulation bandwidths (Spread %)

to a few discrete values. Refer to FS791/2/4 products for appli-

cations requiring 80- to 140-MHz frequency range.

• Digital cameras and camcorders

• Modems

Benefits

• Programmable EMI reduction

• Fast time to market

• Lower cost of compliance

• No degradation in rise/fall times

• Lower component and PCB layer count

Pin Configuration

Block Diagram

Loop Filter

4(6)

Xin

Xout

VDD

250 K

FS78x

FSOUT

VSS

Reference

Divider

1(3)

Xin

Phase

Detector

8 pF

VCO

10 pF.

8 Pin SOIC Package

Modulation

Control

2(4)

Xout

8 pF

VCO / N

FSOUT

VSS

Output

Divider

and

VDD

FS78x

Power Contol

Logic

8(2)

6(8)

VDD

Input Control Logic

VDD

FSOUT

Xin

Mux

Xout

VSS

(TSSOP Pin #)

7(1)

5(7)

3(5)

8 Pin TSSOP Package

VSS

Cypress Semiconductor Corporation

•

3901 North First Street

•

San Jose

•

CA 95134

•

408-943-2600

Document #: 38-07029 Rev. *C

Revised December 14, 2002

12 3 4 5 6 7...11

中文翻译

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与FS781/82/84相关器件

型号	品牌	获取价格	描述	数据表
FS781BT	CYPRESS	获取价格	Clock Generator, 82MHz, CMOS, PDSO8, 4.40 MM, TSSOP-8
FS781BTB	CYPRESS	获取价格	Clock Generator, CMOS, PDSO8, 0.169 INCH, TSSOP-8
FS781BTT	CYPRESS	获取价格	Clock Generator, 82MHz, CMOS, PDSO8, 4.40 MM, TSSOP-8
FS781BZB	CYPRESS	获取价格	Clock Generator, CMOS, PDSO8, 0.150 INCH, SOIC-8
FS781BZBT	CYPRESS	获取价格	Clock Generator, 82MHz, CMOS, PDSO8, 0.150 INCH, MS-012, SOIC-8
FS782	CYPRESS	获取价格	Low EMI Spectrum Spread Clock
FS782BT	CYPRESS	获取价格	Clock Generator, 82MHz, CMOS, PDSO8, 4.40 MM, TSSOP-8
FS782BTB	CYPRESS	获取价格	Clock Generator, CMOS, PDSO8, 0.169 INCH, TSSOP-8
FS782BTT	CYPRESS	获取价格	Clock Generator, 82MHz, CMOS, PDSO8, 4.40 MM, TSSOP-8
FS782BZB	CYPRESS	获取价格	Clock Generator, CMOS, PDSO8, 0.150 INCH, SOIC-8

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