CL = 6 + 6 + 4 = 14 pF 2 CSTRAY" />
參數資料
型號: LMK04033BEVAL
廠商: National Semiconductor
文件頁數: 43/65頁
文件大?。?/td> 0K
描述: BOARD EVAL FOR LMK04033BISQ
標準包裝: 1
系列: PowerWise®
主要目的: 計時,時鐘調節(jié)器
嵌入式:
已用 IC / 零件: LMK04033
主要屬性: 122.88 MHz VCXO
次要屬性: 集成式 PLL 和 VCO
已供物品: 板,線纜,文檔
2
CL = 6 + 6 +
4
= 14 pF
2
CSTRAY
CL = CTUNE + CIN +
C
Po
u
t1
LMK040xx
OSCin
OSCin*
Copt
PLL1 Loop Filter
XTAL
CC1 = 2.2 nF
CC2 = 2.2 nF
R1 = 4.7k
R3 = 10k
Copt
1 nF
R2 = 4.7k
SMV1249-074LF
SNOSAZ8J – SEPTEMBER 2008 – REVISED SEPTEMBER 2011
Figure 16. Reference Design Circuit for Crystal Oscillator Option
Optional Crystal Oscillator Implementation (OSCin/OSCin*)
The LMK04000 family features supporting circuitry for a discretely implemented oscillator driving the OSCin port
pins. Figure 16 illustrates a reference design circuit for a crystal oscillator:
This circuit topology represents a parallel resonant mode oscillator design. When selecting a crystal for parallel
resonance, the total load capacitance, CL, must be specified. The load capacitance is the sum of the tuning
capacitance (CTUNE), the capacitance seen looking into the OSCin port (CIN), and stray capacitance due to PCB
parasitics (CSTRAY), and is given by:
CTUNE is provided by the varactor diode shown in Figure 16, Skyworks model SMV1249-074. A dual diode
package with common cathode and provides the variable capacitance for tuning. The single diode capacitance
ranges from approximately 31 pF at 0.3 V to 3.4 pF at 3 V. The capacitance range of the dual package (anode to
anode) is approximately 15.5 pF at 3 V to 1.7 pF at 0.3 V. The desired value of VTUNE applied to the diode should
be VCC/2, or 1.65 V for VCC = 3.3 V. The typical performance curve from the data sheet for the SMV1249-074
indicates that the capacitance at this voltage is approximately 6 pF (12 pF/2).
The nominal input capacitance (CIN) of the LMK04000 family OSCin pins is 6 pF. The stray capacitance (CSTRAY)
of the PCB should be minimized by arranging the oscillator circuit layout to achieve trace lengths as short as
possible and as narrow as possible trace width (50
Ω characteristic impedance is not required). As an example,
assume that CSTRAY is 4 pF. The total load capacitance is nominally:
Consequently the load capacitance specification for the crystal in this case should be nominally 14 pF.
48
Copyright 2008–2011, Texas Instruments Incorporated
相關PDF資料
PDF描述
H3AWH-6418G IDC CABLE - HSC64H/AE64G/HPL64H
M3WWK-1406R IDC CABLE - MPL14K/MC14M/MPL14K
3-1906012-2 CA 2.0MM OFNR 50/125,LC SEC RED
GBB09DHLR CONN EDGECARD 18POS .050 DIP SLD
M3KKK-1406R IDC CABLE - MPK14K/MC14M/MPK14K
相關代理商/技術參數
參數描述
LMK04033BEVAL/NOPB 功能描述:時鐘和定時器開發(fā)工具 LMK04033BISQ EVAL BOARD RoHS:否 制造商:Texas Instruments 產品:Evaluation Modules 類型:Clock Conditioners 工具用于評估:LMK04100B 頻率:122.8 MHz 工作電源電壓:3.3 V
LMK04033BISQ 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Low-Noise Clock Jitter Cleaner with Cascaded PLLs
LMK04033BISQ/NOPB 功能描述:時鐘合成器/抖動清除器 RoHS:否 制造商:Skyworks Solutions, Inc. 輸出端數量: 輸出電平: 最大輸出頻率: 輸入電平: 最大輸入頻率:6.1 GHz 電源電壓-最大:3.3 V 電源電壓-最小:2.7 V 封裝 / 箱體:TSSOP-28 封裝:Reel
LMK04033BISQE 制造商:Texas Instruments 功能描述:Clock Conditioner 48-Pin LLP EP T/R 制造商:Texas Instruments 功能描述:PRECISION CLOCK CONDITIONER, 48LLP
LMK04033BISQE/NOPB 功能描述:時鐘合成器/抖動清除器 RoHS:否 制造商:Skyworks Solutions, Inc. 輸出端數量: 輸出電平: 最大輸出頻率: 輸入電平: 最大輸入頻率:6.1 GHz 電源電壓-最大:3.3 V 電源電壓-最小:2.7 V 封裝 / 箱體:TSSOP-28 封裝:Reel