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CD-700-LAC-GCB-77.760 参数 Datasheet PDF下载

CD-700-LAC-GCB-77.760图片预览
型号: CD-700-LAC-GCB-77.760
PDF下载: 下载PDF文件 查看货源
内容描述: 基于锁相环完整的VCXO [Complete VCXO Based Phase Lock Loop]
分类和应用: 石英晶振压控振荡器
文件页数/大小: 14 页 / 123 K
品牌: VECTRON [ Vectron International, Inc ]
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CD-700, VCXO Based PLL  
VCXO and Absolute Pull Range (APR) Specification  
The CD-700’s VCXO is a varactor tuned crystal oscillator, which produces an output frequency  
proportional to the control voltage (pin 16). The frequency deviation of the CD-700 VCXO is specified in  
terms of Absolute Pull Range (APR). APR provides the user with a guaranteed specification for minimum  
available frequency deviation over all operating conditions. Operating conditions include power supply  
variation, operating temperature range, and differences in output loading and changes due to aging.  
A CD-700 VCXO with an APR of +/-50 ppm will track a +/-50 ppm reference source over all  
operating conditions. The fourth character of the product code in Table 7 specifies absolute Pull  
Range (APR). Please see Vectron’s web site (www.vectron.com) for the APR Application Note.  
APR is tested at 0.5 and 4.5 volts for the 5.0 volt option and 0.3 and 3.0 volts for the 3.3 volt option.  
VCXO Aging  
Quartz oscillators typically exhibit a part per million shift in output frequency during aging. The major  
factors, which lead to this shift, are changes in the mechanical stress on the crystal and mass-loading on  
the crystal.  
As the oscillator ages, relaxation of the crystal mounting stress or transfer of environmental stress  
through the package to the crystal mounting arrangement can lead to frequency variations. VI has  
minimized these two effects through the use of a miniature AT-cut strip resonator crystal which allows a  
superior mounting arrangement. This results in minimal relaxation and almost negligible environmental  
stress transfer.  
VI has eliminated the impact of mass loading by ensuring hermetic integrity and minimizing out-gassing  
by limiting the number of internal components through the use of ASIC technology. Mass-loading on the  
crystal generally results in a frequency decrease and is typically due to out-gassing of material within a  
hermetic package or from contamination by external material in a non-hermetic package.  
Under normal operating conditions the CD-700 will typically exhibit 2 ppm aging in the first year of  
operation. The device will then typically exhibit 1 ppm aging the following year with a logarithmic decline  
each year thereafter.  
Frequency Divider Feature  
The lowest available VCXO OUT1 frequency is 1.000 MHz. To achieve lower frequencies, OUT1 is  
divided by a 2n counter (n = 1 to 8) and is the OUT2 frequency. The divider values (2, 4, 8, 16, 32, 64,  
128 and 256) are set at the factory, so it is user selectable upon ordering only. In addition, a disabled  
OUT2 option is also available. To achieve 1.024 MHz, a CD-700 with OUT1 frequency equal to 16.384  
MHz and a divider value equal to 16 would be used. Additional external divider circuits can be used to  
further lower or change the frequency.  
Vectron International, 267 Lowell Rd, Hudson NH 03051-4916  
Page 6 of 14  
Tel: 1-88-VECTRON-1 Web: www.vectron.com  
Rev : 06Apr08  
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