CX-2520SB View Datasheet(PDF) - Kyocera Kinseki Corpotation

Part Name

Description

View to exact match

CX-2520SB

Crystal Units Surface Mount Type

Kyocera Kinseki Corpotation 

Handling Notes

The oscillation start-up conditions are described as

RL   R 

and in order to oscillate the crystal unit accurately, it must be designed such that the negative resistance of the oscillation

circuit becomes bigger comparing with the resonance resistance value at the time of loading. This ratio is called oscillation

margin degree MOSC and it is one of critical factors when designing the oscillation circuit and is described as below.

For oscillation circuit designing conditions, it is recommended that an oscillation circuit be designed using a negative

resistance of a value five to ten times or more larger than RL calculated from the resonance resistance specification value.

MOSC   R  / RL  5

In a steady oscillation state, the load resonance resistance is given as follows:

RL   R 

The mutual conductance of the oscillation circuit decreases after the oscillation has started to continuously compensate for

the power loss due to the load resonance resistance of the crystal unit, which continues oscillation.

The frequency condition is given as follows:

XL  XC, XL  XC  0

As shown in the following figure, the reactance of the crystal unit varies to a value matching the load capacitance of the

oscillation circuit CL  XC. Thus an oscillation frequency is determined.

+X

fp

fs

fL

 Le Frequency

f s : Series resonance frequency

f L : Load resonance frequency

f p : Parallel resonance frequency

–1/C L

–X

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