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参数资料
| 型号： | ICS8431AMI-21LF |
| 厂商： | INTEGRATED DEVICE TECHNOLOGY INC |
| 元件分类： | 时钟产生/分配 |
| 英文描述： | 350 MHz, OTHER CLOCK GENERATOR, PDSO28 |
| 封装： | 7.50 X 18.05 MM, 2.25 MM HEIGHT, ROHS COMPLIANT, MS-013, MO-119, SOIC-28 |
| 文件页数： | 16/16页 |
| 文件大小： | 256K |
| 代理商： | ICS8431AMI-21LF |
8431AMI-21
www.icst.com/products/hiperclocks.html
REV. A AUGUST 2, 2005
9
Integrated
Circuit
Systems, Inc.
ICS8431I-21
350MHZ, LOW JITTER, CRYSTAL OSCILLATOR-
TO
-3.3V LVPECL FREQUENCY SYNTHESIZER
SPREAD SPECTRUM
Spread-spectrum clocking is a frequency modulation tech-
nique for EMI reduction. When spread-spectrum is enabled,
a 30kHz triangle waveform is used with 0.5% down-spread
(+0.0% / -0.5%) from the nominal 200MHz clock frequency.
An example of a triangle frequency modulation profile is shown
in
Figure 4A below. The ramp profile can be expressed as:
Fnom = Nominal Clock Frequency in Spread OFF mode
(200MHz with 16MHz IN)
Fm = Nominal Modulation Frequency (30kHz)
δ = Modulation Factor (0.5% down spread)
(1 -
δ) fnom + 2 fm x δ x fnom x t when 0 < t <
,
(1 -
δ) fnom - 2 fm x δ x fnom x t when
< t <
1
2 fm
1
2 fm
1
fm
The ICS8431I-21 triangle modulation frequency deviation will
not exceed 0.6% down-spread from the nominal clock fre-
quency (+0.0% / -0.5%). An example of the amount of down
spread relative to the nominal clock frequency can be seen in
the frequency domain, as shown in
Figure 4B. The ratio of
this width to the fundamental frequency is typically 0.4%, and
will not exceed 0.6%. The resulting spectral reduction will be
greater than 7dB, as shown in
Figure 4B. It is important to
note the ICS8431I-21 7dB minimum spectral reduction is the
component-specific EMI reduction, and will not necessarily
be the same as the system EMI reduction.
FIGURE 4B. 200MHZ CLOCK OUTPUT IN FREQUENCY DOMAIN
(A) SPREAD-SPECTRUM OFF (B) SPREAD-SPECTRUM ON
FIGURE 4A. TRIANGLE FREQUENCY MODULATION
Δ 10 dBm
δ = .4%
B
A
Fnom
(1 -
δ) Fnom
0.5/fm
1/fm
CRYSTAL INPUT INTERFACE
The ICS8431I-21 has been characterized with 18pF parallel resonant
crystals. The capacitor values, C1 and C2, shown in
Figure 3 below
were determined using a 25MHz, 18pF parallel resonant crystal and
Figure 3. CRYSTAL INPUT INTERFACE
were chosen to minimize the ppm error. The optimum C1 and C2
values can be slightly adjusted for different board layouts.
C1
22p
X1
18pF Parallel Crystal
C2
22p
XTAL_OUT
XTAL_IN
相关PDF资料 |
PDF描述 |
|---|---|
| ICS8431CM-01LF | 200 MHz, OTHER CLOCK GENERATOR, PDSO28 |
| ICS8431CM-11T | 255 MHz, OTHER CLOCK GENERATOR, PDSO28 |
| ICS8431CM-11LFT | 255 MHz, OTHER CLOCK GENERATOR, PDSO28 |
| ICS8431DMI-01 | 200 MHz, OTHER CLOCK GENERATOR, PDSO28 |
| ICS8431DMI-01LFT | 200 MHz, OTHER CLOCK GENERATOR, PDSO28 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ICS8431AMI-21LFT | 功能描述:IC SYNTHESIZER 350MHZ 28-SOIC RoHS:是 类别:集成电路 (IC) >> 时钟/计时 - 时钟发生器，PLL，频率合成器 系列:HiPerClockS™ 标准包装:1,000 系列:- 类型:时钟/频率合成器，扇出分配 PLL:- 输入:- 输出:- 电路数:- 比率 - 输入:输出:- 差分 - 输入:输出:- 频率 - 最大:- 除法器/乘法器:- 电源电压:- 工作温度:- 安装类型:表面贴装 封装/外壳:56-VFQFN 裸露焊盘 供应商设备封装:56-VFQFP-EP（8x8） 包装:带卷 (TR) 其它名称:844S012AKI-01LFT |
| ICS8431AMI-21T | 制造商:ICS 制造商全称:ICS 功能描述:350MHZ, LOW JITTER, CRYSTAL OSCILLATOR-TO-3.3V LVPECL FREQUENCY SYNTHESIZER |
| ICS8431CM-01 | 制造商:ICS 制造商全称:ICS 功能描述:200MHZ, LOW JITTER, LVPECL FREQUENCY SYNTHESIZER |
| ICS8431CM-01T | 制造商:ICS 制造商全称:ICS 功能描述:200MHZ, LOW JITTER, LVPECL FREQUENCY SYNTHESIZER |
| ICS8431CM-11 | 制造商:ICS 制造商全称:ICS 功能描述:255MHZ, LOW JITTER, LVPECL FREQUENCY SYNTHESIZER |
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