W149HT

更新时间： 2024-02-26 01:52:10

品牌	Logo	应用领域
赛普拉斯 - CYPRESS		/
页数	文件大小	规格书
14页	159K
描述
Processor Specific Clock Generator, 124MHz, CMOS, PDSO48, 0.300 INCH, SSOP-48

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W149HT 技术参数

生命周期：	Obsolete	零件包装代码：	SSOP
包装说明：	SSOP,	针数：	48
Reach Compliance Code：	unknown	ECCN代码：	EAR99
HTS代码：	8542.39.00.01	风险等级：	5.49
其他特性：	ALSO REQUIRES AT 2.5V SUPPLY	JESD-30 代码：	R-PDSO-G48
JESD-609代码：	e0	长度：	15.875 mm
湿度敏感等级：	1	端子数量：	48
最高工作温度：	70 °C	最低工作温度：
最大输出时钟频率：	124 MHz	封装主体材料：	PLASTIC/EPOXY
封装代码：	SSOP	封装形状：	RECTANGULAR
封装形式：	SMALL OUTLINE, SHRINK PITCH	峰值回流温度（摄氏度）：	220
主时钟/晶体标称频率：	14.318 MHz	认证状态：	Not Qualified
座面最大高度：	2.794 mm	最大供电电压：	3.465 V
最小供电电压：	3.135 V	标称供电电压：	3.3 V
表面贴装：	YES	技术：	CMOS
温度等级：	COMMERCIAL	端子面层：	TIN LEAD
端子形式：	GULL WING	端子节距：	0.635 mm
端子位置：	DUAL	处于峰值回流温度下的最长时间：	NOT SPECIFIED
宽度：	7.5 mm	uPs/uCs/外围集成电路类型：	CLOCK GENERATOR, PROCESSOR SPECIFIC
Base Number Matches：	1

W149

Where is the percentage of deviation and is the frequency

in MHz where the reduction is measured.

Spread Spectrum Clocking

The device generates a clock that is frequency modulated in

order to increase the bandwidth that it occupies. By increasing

the bandwidth of the fundamental and its harmonics, the am-

plitudes of the radiated electromagnetic emissions are re-

duced. This effect is depicted in Figure 3.

The output clock is modulated with a waveform depicted in

Figure 4. This waveform, as discussed in “Spread Spectrum

Clock Generation for the Reduction of Radiated Emissions” by

Bush, Fessler, and Hardin produces the maximum reduction

in the amplitude of radiated electromagnetic emissions. The

deviation selected for this chip is either –0.5% or ±0.5% of the

selected frequency. Figure 4 details the Cypress spreading

pattern. Cypress does offer options with more spread and

greater EMI reduction. Contact your local Sales representative

for details on these devices.

As shown in Figure 3, a harmonic of a modulated clock has a

much lower amplitude than that of an unmodulated signal. The

reduction in amplitude is dependent on the harmonic number

and the frequency deviation or spread. The equation for the

reduction is:

dB = 6.5 + 9*log10(P) + 9*log10(F)

Spread Spectrum clocking cannot be deactivated on the

W149.

SSFTG

Typical Clock

Frequency Span (MHz)

Center Spread

Figure 3. Clock Harmonic with and without SSCG Modulation Frequency Domain Representation

MAX (+0.5%)

MIN (–0.5%)

Figure 4. Typical Modulation Profile

1 2 345 6 7...14

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