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Specifications subject to change without notice. All dimensions in inches. © Copyright 2012 The Connor-Winfield Corporation
Application Note
AN2093
Page
20
Revision
P01
Date
10 May 2013
2111 Comprehensive Drive
Aurora, Illinois 60505
Phone: 630-851-4722
Fax: 630- 851- 5040
www.conwin.com
Design Checklist
5.4 OCXO Layout Considerations
•
Always place OCXO as close to timing circuitry as possible..
•
Always adhere to stated loading specifications for RF output of OCXO and consider using NPO / COG
capacitors to create equivalent loading capacitance for optimal capacitance vs. temperature characteristics.
•
It is recommended to place a 10uF to 47uF bulk capacitor as close to as possible to the VCC pin of the OCXO.
•
Place a small ceramic decoupling capacitor typically X7R with a 2 to 3 ohm reactance at the output frequency
of the OCXO to shunt any noise on the supply rail to ground.
•
Calculate via size to ensure sufficient current is available to the OCXO at the anticipated maximum board
temperature which may be SIGNIFICANTLY higher than ambient air temperature.
•
Connect the ground of the control voltage source as close as possible to the OCXO ground to minimize trace
impedance.
•
Open a window in all ground and power planes under the device. Excessive thermal losses may result in
higher than normal current consumption or complete device failure.
•
Do not place OCXO in path or turbulent airflow which could cause quickly changing temperature fluctuations
that could compromise the oven core temperature.
•
[Optional] Route a thermal “moat” to prevent thermal energy transfers between the OCXO and board.
•
[Optional] Use plastic and metal covers can be used to further reduce small temperature fluctuations in the
system by reducing variable air flow across the device.
•
DO NOT connect any signals to “Do Not Connect” (D.N.C.) pins. These are FACTORY use only. DNC pads
may be soldered down to electrically isolated pads for structural support only.
Section 6: References
Chester Simpson "Linear and Switching Voltage Regulator Fundamentals"
National Semiconductor http://www.national.com/assets/en/appnotes/f4.pdf
Habeeb Ur Rahman Mohammed, Ph.D " Supply Noise Effect on Oscillator Phase Noise,"
Texas Instruments, Application Report SLWA066–November 2011 http://www.ti.com/lit/an/slwa066/slwa066.pdf
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