TDA5255XT Infineon Technologies, TDA5255XT Datasheet - Page 49

• Manufacturer Part Number: TDA5255XT
• Manufacturer: Infineon Technologies

Specifications of TDA5255XT

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 4.4mm
• Product Length (mm): 9.7mm
• Operating Supply Voltage (min): 2.1V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Compliant

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:
Table 3-1
The crystal oscillator in the TDA5255 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
Data Sheet
t
δ
Independent variable
δ
Start
frequency of quartz >
C
D
L
=
~
δ
where:
f
δ
−
L OSC >
S
C
´
R
C 1 >
C 0 >
C L >
L
f
Crystal and crystal oscilator dependency
v
S
L
−
as shown in formula [3-17].
1
=
R
2
ext
(
C
-R:
R
0
−
ext
+
C
:
C
1
L
)
2
is the negative impedance of the oscillator
see Figure 3-15
is the sum of all external resistances (e.g. R
other resistance that may be present in the circuit,
see Figure 3-14
Relative Tolerance Maximum Deviation
L
(specified by the crystal supplier) is transformed to the
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TDA5255 E1
t Start-up
Version 1.2
Application
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2007-02-26