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| 型号： | SL28774ELIT |
| 厂商： | Silicon Laboratories Inc |
| 文件页数： | 2/19页 |
| 文件大小： | 0K |
| 描述： | IC CLOCK CK505 CALPELLA 32QFN |
| 标准包装： | 2,500 |
| 系列： | EProClock® |
| 类型： | 时钟/频率发生器，多路复用器 |
| PLL： | 是 |
| 主要目的： | Intel CPU 服务器 |
| 输入： | 晶体 |
| 输出： | HCSL，LVCMOS |
| 电路数： | 1 |
| 比率 - 输入:输出： | 1:8 |
| 差分 - 输入:输出： | 无/是 |
| 频率 - 最大： | 133MHz |
| 电源电压： | 3.135 V ~ 3.465 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | * |
| 封装/外壳： | * |
| 供应商设备封装： | * |
| 包装： | * |
SL28774
......................Document #: 001-08400 Rev ** Page 10 of 19
The SL28774 requires a Parallel Resonance Crystal. Substi-
tuting a series resonance crystal causes the SL28774 to
operate at the wrong frequency and violates the ppm specifi-
cation. For most applications there is a 300-ppm frequency
shift between series and parallel crystals due to incorrect
loading.
Crystal Loading
Crystal loading plays a critical role in achieving low ppm perfor-
mance. To realize low ppm performance, use the total capac-
itance the crystal sees to calculate the appropriate capacitive
loading (CL).
Figure 1 shows a typical crystal configuration using the two
trim capacitors. It is important that the trim capacitors are in
series with the crystal. It is not true that load capacitors are in
parallel with the crystal and are approximately equal to the
load capacitance of the crystal.
Calculating Load Capacitors
In addition to the standard external trim capacitors, consider
the trace capacitance and pin capacitance to calculate the
crystal loading correctly. Again, the capacitance on each side
is in series with the crystal. The total capacitance on both side
is twice the specified crystal load capacitance (CL). Trim
capacitors are calculated to provide equal capacitive loading
on both sides.
,
Use the following formulas to calculate the trim capacitor
values for Ce1 and Ce2.
CL....................................................Crystal load capacitance
CLe......................................... Actual loading seen by crystal
using standard value trim capacitors
Ce..................................................... External trim capacitors
Cs .............................................. Stray capacitance (terraced)
Ci ...........................................................Internal capacitance
(lead frame, bond wires, etc.)
PD# = 0 (Power down)
Low
Hi-z
Low
Table 6. Output Driver Status
Table 7. Crystal Recommendations
Frequency
(Fund)
Cut
Loading
Load Cap
Drive
(max.)
Shunt Cap
(max.)
Motional
(max.)
Tolerance
(max.)
Stability
(max.)
Aging
(max.)
14.31818 MHz
AT
Parallel
20 pF
0.1 mW
5 pF
0.016 pF
35 ppm
30 ppm
5 ppm
Figure 1. Crystal Capacitive Clarification
Figure 2. Crystal Loading Example
Load Capacitance (each side)
Total Capacitance (as seen by the crystal)
Ce = 2 * CL – (Cs + Ci)
Ce1 + Cs1 + Ci1
1
+
Ce2 + Cs2 + Ci2
1
()
1
=
CLe
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相关代理商/技术参数 |
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|---|---|
| SL28779ELC | 功能描述:时钟发生器及支持产品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| SL28779ELCT | 功能描述:时钟发生器及支持产品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| SL28779ELI | 功能描述:时钟发生器及支持产品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| SL28779ELIT | 功能描述:时钟发生器及支持产品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| SL28DB200AZC | 功能描述:时钟发生器及支持产品 PCIe fam 1diff input 2 diff outputs RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
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