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| 型号： | SL28540ALC |
| 厂商： | SILICON LABORATORIES |
| 元件分类： | 时钟产生/分配 |
| 英文描述： | OTHER CLOCK GENERATOR, QCC56 |
| 封装： | 8 X 8 MM, LEAD FREE, QFN-56 |
| 文件页数： | 3/25页 |
| 文件大小： | 267K |
| 代理商： | SL28540ALC |
SL28540
Rev 1.2, September 15, 2008
Page 11 of 25
The SL28540 requires a Parallel Resonance Crystal. Substi-
tuting a series resonance crystal causes the SL28540 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.)
0
1
SW_PCI
SW PCI_STP# Function
0 = SW PCI_STP assert, 1 = SW PCI_STP deassert
When this bit is set to 0, all STOPPABLE PCI, PCIF and SRC outputs are
stopped in a synchronous manner with no short pulses.
When this bit is set to 1, all STOPPED PCI, PCIF and SRC outputs are
resumed in a synchronous manner with no short pulses.
Byte 14: Control Register 14
Bit
@Pup
Name
Description
Table 5. 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
X T A L
C e 2
C e 1
C s 1
C s 2
X 1
X 2
C i1
C i2
C lo c k C h ip
T r a c e
2 . 8 p F
T r im
3 3 p F
P in
3 t o 6 p
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 |
参数描述 |
|---|---|
| SL28540ALCT | 功能描述:时钟发生器及支持产品 Low Power for Intel Mobile 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 |
| SL28541BQCR | 功能描述:时钟发生器及支持产品 Montevina, Atom 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 |
| SL28541BQCRT | 功能描述:时钟发生器及支持产品 Montevina, Atom 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 |
| SL28541BZC | 功能描述:时钟发生器及支持产品 Montevina 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 |
| SL28541BZC-2 | 功能描述:时钟发生器及支持产品 Montevina, Atom 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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