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A recommended oscillation circuit examples when using a crystal unit

The following circuit diagrams are examples of the recommended oscillation circuits when using crystal units.
After determining the frequency band and overtone order in the specifications, we considered IC circuits or discrete transistors to determine the conditions for various circuit elements.

1. Frequency Range : 12 to 20 MHz Overtone order : Fundamental Load capacitance CL = 20 pF

2. Frequency Range : 3 to 25 MHz Overtone order : Fundamental

3. Frequency Range : 3 to 25 MHz Overtone order : Fundamental

4. Frequency Range : 25 to 50MHz Overtone order : Fundamental

5. Frequency Range : 30 to 60 MHz Overtone order : 3rd overtone

6. Frequency Range : 16 to 80 MHz max Overtone order : 3rd, 5th overtone
Load capacitance CL : Series resonance

7. Frequency Range : 80 to 140 MHz max
Overtone order : 3rd, 5th overtone
Load capacitance CL : Series resonance

8. Example of Un-buffered IC Oscillation Circuit Connection

To prevent coupling between input and output:
  • Input pin 3 and output pin 7 are placed apart.
  • The inverter in the center stops operation.

9. Example of IC Internal Oscillation Circuit Connection

For proper operation
  • Resistor R1 is not required if the IC has a built-in resistor.
  • Resistance R2 is required to prevent abnormal oscillation.
  • Use this circuit configuration as a prototype.
  • Mount Resistor R2 on the output side after checking the terminal functions of the IC.


Notes on Mounting
1. The line connecting the components should be the shortest distance including the ground line to avoid unnecessary stray capacitance.
2.Do not cross the oscillator circuit section with the signal lines of other circuit sections on the same substrate.
3.Output frequency is slightly affected by differences in IC manufacturers, variations in circuit parameter, and component layout.
For details, please feel free to contact us.

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