tda5255e1 Infineon Technologies Corporation, tda5255e1 Datasheet - Page 48

• Manufacturer Part Number: tda5255e1
• Description: Ask/fsk 434mhz Wireless Transceiver
• Manufacturer: Infineon Technologies Corporation

Confidential
3.2
The equivalent schematic of the crystal with its parameters specified by the crystal manufacturer
can be taken from the subsequent figure.
Here also the load capacitance of the crystal C L , which the crystal wants to see in order to oscillate
at the desired frequency, can be seen.
Figure 3-14
Therefore the Resonant Frequency f s of the crystal is defined as:
The Series Load Resonant Frequency f S ‘ of the crystal is defined as:
regarding Figure 3-14
f s ’ is the nominal frequency of the crystal with a specified load when tested by the crystal
manufacturer.
Pulling Sensitivity of the crystal is defined as the magnitude of the relative change in frequency
relating to the variation of the load capacitor.
Preliminary Specification
f
f
S
S
Crystal Oscillator
`
=
=
2
2
Crystal
p
p
L
1
L
1
1
1
*
*
C
L
C
C
1
C
-R
1
1
1
0
:
:
:
*
1
motional inductance of the crystal
motional capacitance of the crystal
shunt capacitance of the crystal
+
C
0
C
+
1
C
L
L
1
48
C
C
1
0
R
1
[3 – 14]
[3 – 13]
C
L
TDA5255 E1
Version 1.1
Application
2002-11-28
Crystal.wmf