TDA5252G2 INFINEON [Infineon Technologies AG], TDA5252G2 Datasheet - Page 47

• Manufacturer Part Number: TDA5252G2
• Description: ASK/FSK 915MHz Wireless Transceiver
• Manufacturer: INFINEON [Infineon Technologies AG]

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 3-11
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.
Choosing C L as large as possible results in a small pulling sensitivity. On the other hand a small C L
keeps the influence of the serial inductance and the tolerances associated to it small (see formula
[3-17]).
Start-up Time
The proportionality of L 1 and C 1 of the crystal is defined by formula [3-13]. For a crystal with a small
C 1 the start -up time will also be slower. Typically the lower the value of the crystal frequency, the
lower the C 1 .
A short conclusion regarding crystal and crystal oscillator dependencies is shown in the following
table:
Data Sheet
t
δ
δ
Start
C
D
L
=
~
δ
where:
f
f
δ
−
f
S
S
S
C
`
´
R
=
=
L
f
S
L
2
2
−
π
π
1
=
R
2
L
ext
1
L
(
1
1
C
-R:
R
1
*
*
0
−
ext
C
C
+
1
C
:
1
C
1
*
L
)
2
1
+
is the negative impedance of the oscillator
see Figure 3-11
is the sum of all external resistances (e.g. R
other resistance that may be present in the circuit,
see Figure 3-10
C
0
C
+
1
C
L
47
[3 – 16]
[3 – 15]
[3 – 13]
1
or any
TDA5252 G2
Version 1.1
Application
2007-02-26