TDA8295_09 Datasheet, PDF (73/83 Pages) NXP Semiconductors – Digital global standard low IF demodulator for analog TV and FM radio

NXP Semiconductors
TDA8295
Digital global standard low IF demodulator for analog TV and FM radio
3. Pin 6 and pin 36 (both internally connected pins) can still stay connected to the 1.2 V
power supply, as done in the PCBs for the predecessor TDA8290 without harm.
However, take grounds for new designs, because they are more easily accessible on
a PCB.
13.7 Crystal connection
The typical crystal frequency value is 16 MHz. The values of the passive components
depend on crystal manufacturer. The oscillator can be set in two configurations depending
on the origin of the crystal. Figure 17 describes the case of an crystal shared with the
tuner and the TDA8295 (Slave mode), Figure 18 the case of an crystal dedicated to the
TDA8295 (Oscillator mode).
TDA8295_C2_2
Product data sheet
TDA8295
TDA8295
Rbias
XIN
100 nF
XOUT
clock signal
from tuner
n.c.
001aah363
Rbias
XIN
XOUT
XTAL
C1
GND
C2
GND
001aah364
Slave mode
Fig 17. Reference clock application
Oscillator mode
Fig 18. Oscillator application
In Oscillator mode, only a crystal and the load capacitances C1 and C2 need to be
connected externally since the feedback resistance is integrated on chip. In this mode the
oscillator gain stage can have a normal or large transconductance, determined by the HF
bit (see also Table 61). A large transconductance is required for higher oscillation
frequencies, higher series resistance of the crystal and higher external load capacitors.
For an accurate time reference it is advised to use the load capacitors as specified in
Table 73. C_L is the typical load capacitance of the crystal and is usually specified by the
crystal manufacturer.
Table 73. Crystal parameters together with external components
Fundamental
oscillation
frequency
Bit HF = 0
Crystal load
capacitance
C_L(xtal) (pF)
Crystal series External load capacitors
resistance R_{s(xtal) C1 (pF)}
(Ω)
C2 (pF)
1 MHz to 5 MHz 10
< 300
18
18
20
< 300
39
39
30
< 300
56
56
5 MHz to 10 MHz 10
< 300
18
18
20
< 200
39
39
30
< 100
56
56
10 MHz to
10
< 160
18
18
15 MHz
20
< 60
39
39
Rev. 02 — 27 November 2009
© NXP B.V. 2009. All rights reserved.
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