TDA5252G2 INFINEON [Infineon Technologies AG], TDA5252G2 Datasheet - Page 48

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

Table 3-1
The crystal oscillator in the TDA5252 is a NIC (negative impedance converter) oscillator type. The
input impedance of this oscillator is a negative impedance in series to an inductance. Therefore the
load capacitance of the crystal C
capacitance C
Figure 3-12
With the aid of this formula it becomes obvious that the higher the serial capacitance C V is, the
higher is the influence of L OSC .
The tolerance of the internal oscillator inductivity is much higher, so the inductivity is the dominating
value for the tolerance.
FSK modulation and tuning are achieved by a variation of C
Data Sheet
Independent variable
frequency of quartz >
C
L
=
L OSC >
C
1
V
C 1 >
C 0 >
C L >
Crystal and crystal oscilator dependency
v
−
as shown in formula [3-17].
Crystal Oscillator
ω
1
2
L
OSC
C
ω:
L
OSC
L
:
↔
:
C
V
-R
=
crystal load capacitance for nominal frequency
angular frequency
inductivity of the crystal oscillator - typ: 2.75µH with pad of board
C
Relative Tolerance Maximum Deviation
1
L
+
L
ω
1
2
TDA 5250
(specified by the crystal supplier) is transformed to the
L
L
OSC
>>>
>>
>>
OSC
<
>
48
f, C
v
.
Result
L
>>
<
>
>
<
C
V
2.5µH without pad
[3 – 17]
TDA5252 G2
t Start-up
Version 1.1
Application
<<
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2007-02-26
QOSZ_NIC.wmf