Datasheet > W144

W144

更新时间： 2024-02-22 03:42:55

品牌	Logo	应用领域
SPECTRALINEAR		/
页数	文件大小	规格书
13页	201K
描述
440BX AGPset Spread Spectrum Frequency Synthesizer

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技术参数
数据手册

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W144 技术参数

是否Rohs认证：	符合	生命周期：	Active
Reach Compliance Code：	compliant	ECCN代码：	EAR99
HTS代码：	8541.40.20.00	风险等级：	5.77
其他特性：	HIGH RELIABILITY	颜色：	YELLOW
配置：	SINGLE	最大正向电流：	0.03 A
透镜类型：	DIFFUSED	标称发光强度：	3.0 mcd
安装特点：	RADIAL MOUNT	功能数量：	1
端子数量：	2	最高工作温度：	85 °C
最低工作温度：	-40 °C	光电设备类型：	SINGLE COLOR LED
总高度：	7 mm	包装方法：	BULK
峰值波长：	590 nm	形状：	RECTANGULAR
尺寸：	3.9 mm	表面贴装：	NO
端子节距：	2.54 mm	视角：	110 deg
Base Number Matches：	1

W144 数据手册

W144

Jumper Options

Output Strapping Resistor

Series Termination Resistor

V_DD

10 k

Clock Load

W144

Output

Buffer

Power-on

Reset

Timer

Resistor Value R

Hold

Output

Low

Output Three-state

Data

Latch

Figure 2. Input Logic Selection Through Jumper Option

Spread Spectrum clocking is activated or deactivated by

selecting the appropriate values for bits 1–0 in data byte 0 of

the I²C data stream. Refer to Table 7 for more details.

Spread Spectrum Feature

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 ampli-

tudes of the radiated electromagnetic emissions are reduced.

This effect is depicted in Figure 3.

5dB/div

SSFTG

Typical Clock

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)

Where P is the percentage of deviation and F is the frequency

in MHz where the reduction is measured.

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 specified in Table 7. 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.

Frequency Span (MHz)

-SS%

+SS%

Figure 3. Clock Harmonic with and without SSCG

Modulation Frequency Domain Representation

MAX (+0.5ꢀ)

MIN (–0.5ꢀ)

Figure 4. Typical Modulation Profile

Rev 1.0,November 21, 2006

Page 4 of 13

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