 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
MK3771-1 Datasheet(PDF) 1 Page - Integrated Circuit Systems |
|
||||||||||||||||||||||||||||||
MK3771-1 Datasheet(HTML) 1 Page - Integrated Circuit Systems |
|
|
1 / 6 page  MAN05 G 1 Revision 050603 Integr ated Circuit Sy stems l 5 25 Race Street, San Jose, CA 9 512 6 l tel (40 8 ) 2 95-98 00 l www.icst.com USING MICROCLOCK’S INTEGRATED VCXO PRODUCTS MicroClock Application Note MAN05 MicroClock has developed a patented technique to integrate a Voltage Controlled Crystal Oscillator (VCXO) function into clock synthesizer products. The VCXO oscillator circuit, in conjunction with an external crystal, allows the output clocks to be pulled (varied up or down in frequency) more than 100 parts per million (+100ppm or 0.01%), under control of an analog input voltage. The MK27XX and MK37XX series of products integrate a VCXO oscillator and a PLL, creating a cost effective VCXO clock solution. Our communication synchronization products (MK2049, MK2058, MK2059, MK2069) use the integrated VCXO as a circuit block, and this information applies to these products also. Crystal Selection The crystal is the frequency reference of the VCXO and the overall performance of the circuit depends on the characteristics of it. It is important that the crystal meets all required specifications if the VCXO is expected to work reliably. ICS works with crystal vendors to define, build, and certify crystals that meet these requirements, and the crystal vendors maintain an inventory of these devices in stock. Please see our web site for recommended part numbers. Using a packaged clock oscillator to drive these VCXO products will not work correctly. The clock will be generated, but the frequency cannot be pulled because the VCXO circuit has no control over the oscillator frequency. Crystal Specifications The crystals defined for use with VCXO products have specifications common to all crystals, and additional requirements to insure VCXO performance. All crystals have specifications for: 1. Frequency tolerance (often called Calibration Accuracy). This is the allowable frequency error from a specified center frequency of the crystal at 25 c. This parameter is specified with a maximum and minimum frequency deviation, expressed in percent (%) or parts per million (ppm). It is typically +/-20ppm for IC VCXO crystal designs. The source of this error term is principally variation in the manufacturing process. 2. Temperature stability. This is the change in frequency allowed as temperature is varied from 25 c to the temperature extremes, hot and cold. This variation is characteristic of a quartz crystal, and the slope and magnitude is controlled by the type of crystal cut and the crystal lattice angle at which the crystal is cut. This parameter is specified with a maximum and minimum frequency deviation, expressed in percent (%) or parts per million (ppm). It is typically +/-30ppm for IC VCXO designs. 3. Load capacitance. This is the capacitance, specified in picofarads (pF), which the oscillator circuit presents to the crystal for the crystal to resonate on frequency. Load Capacitance is comprised of a combination of the circuits’ discrete load capacitance, stray board capacitance, and capacitance internal to the ICS device. Because this includes the stray capacitance of the circuit board, we recommend that pads for small capacitors (CT in figure 1) be provided in your layout to make small adjustments to the total capacitance. Details are given in the Layout Considerations section. 4. Equivalent Series Resistance. This is a term that represents (in ohms) all the losses within the crystal. If this value is too high, the oscillator may have startup problems. 5. Aging. This specifies the amount that the frequency is allowed to drift, long term, and is typically 5ppm in the first year, and logarithmically declines each year thereafter, to not exceed a total of +/-20ppm in 10 years. X1 C T C T C L C L Osci ll at o r Ci rcuit VCX O IC F i gure 1 - V C X O Cir c uit |
Similar Part No. - MK3771-1 |
|
Similar Description - MK3771-1 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
