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參數(shù)資料
| 型號： | SL28774ELI |
| 廠商： | Silicon Laboratories Inc |
| 文件頁數(shù)： | 2/19頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC CLOCK CK505 CALPELLA 32QFN |
| 標準包裝： | 624 |
| 系列： | EProClock® |
| 類型： | 時鐘/頻率發(fā)生器，多路復(fù)用器 |
| PLL： | 是 |
| 主要目的： | Intel CPU 服務(wù)器 |
| 輸入： | 晶體 |
| 輸出： | HCSL，LVCMOS |
| 電路數(shù)： | 1 |
| 比率 - 輸入:輸出： | 1:8 |
| 差分 - 輸入:輸出： | 無/是 |
| 頻率 - 最大： | 133MHz |
| 電源電壓： | 3.135 V ~ 3.465 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | * |
| 封裝/外殼： | * |
| 供應(yīng)商設(shè)備封裝： | * |
| 包裝： | * |
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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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SL28774ELIT | 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Shrink CK505 for Calpella platforms RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-56 |
| SL28779ELC | 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-56 |
| SL28779ELCT | 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-56 |
| SL28779ELI | 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-56 |
| SL28779ELIT | 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Calpella IrnLk JpFrt Ibex Pk Add USB28748 RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-56 |
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