參數(shù)資料
型號: SL28504BZC-2
廠商: Silicon Laboratories Inc
文件頁數(shù): 4/27頁
文件大小: 0K
描述: IC CLOCK GEN EAGLELAKE 56TSSOP
標準包裝: 35
類型: 時鐘/頻率發(fā)生器
PLL:
主要目的: Intel CPU 服務器
輸入: 晶體
輸出: HCSL,LVCMOS
電路數(shù): 1
比率 - 輸入:輸出: 1:19
差分 - 輸入:輸出: 無/是
頻率 - 最大: 400MHz
電源電壓: 3.135 V ~ 3.465 V
工作溫度: 0°C ~ 85°C
安裝類型: 表面貼裝
封裝/外殼: 56-TFSOP(0.240",6.10mm 寬)
供應商設備封裝: 56-TSSOP
包裝: 管件
SL28504-2
...................... DOC #: SP-AP-0051 (Rev. AA) Page 12 of 27
The SL28504-2 requires a Parallel Resonance Crystal. Substi-
tuting a series resonance crystal causes the SL28504-2 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.)
7
0
SMSW_EN
Enable Smooth Switching
0 = Disabled, 1= Enabled
6
0
SMSW_SEL
Smooth switch select
0 = PLL1, 1 = PLL3
5
0
Prog_PCI-E_EN
Programmable PCI-E frequency enable
0 = Disabled, 1= Enabled
4
0
Prog_CPU_EN
Programmable CPU frequency enable
0 = Disabled, 1= Enabled
3
0
RESERVED
2
0
RESERVED
1
0
RESERVED
0
RESERVED
Byte 18: Control Register 18 (continued)
Table 4. 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
XTAL
Ce 2
Ce 1
Cs 1
Cs 2
X1
X2
Ci1
Ci2
Clo c k Ch ip
Tr a c e
2. 8pF
Tr im
33pF
Pin
3 t o 6p
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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SL28504BZC-2T 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Syst Clock Intel Eaglake 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
SL28504BZCT 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Syst Clock Intel Eaglake 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
SL28504BZI 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Syst Clock Intel Eaglake 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
SL28504BZI-2 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Syst Clock Intel Eaglake 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
SL28504BZI-2T 功能描述:時鐘發(fā)生器及支持產(chǎn)品 Syst Clock Intel Eaglake 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