tda8295 NXP Semiconductors, tda8295 Datasheet - Page 23

• Manufacturer Part Number: tda8295
• Description: Tda8295 Digital Global Standard Low If Demodulator For Analog Tv And Fm Radio
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8295_1
Product data sheet
9.3.2 Diverse functions (includes tuner IF AGC Pin mode)
9.3.3 ADC headroom
Table 14.
Legend: * = default value.
Table 15.
Legend: * = default value.
Bit
7
6
5 and 4 -
3
2
1
0
Bit
7 to 4 -
3 to 0 ADC_HEADR[3:0] R/W
Symbol
Symbol
AGC_SEL R/W
AGC_TRI R/W
-
POL_DET R/W
VID_MOD R/W
IF_SWAP R/W
DIV_FUNC register (address 02h) bit description
ADC_HEADR register (address 03h) bit description
Digital global standard low IF demodulator for analog TV and FM radio
Access Value Description
R/W
R/W
Rev. 01 — 4 February 2008
Access Value Description
R/W
0*
1
0*
1
-
0
0
1*
0*
1
0*
1
-
0001*
0010
0100
1000
open-drain output can be used in special applications in
need of a higher control voltage.
pin is in 3-state mode. This mode is useful for paralleling a
channel decoder for instance.
not used
reserved, must be set to logic 0
The polarity detector ensures the proper polarity of the
video signal. So, the sync impulses of the video output are
near ground level.
Selects video modulation. The only standards with positive
video modulation are L and L-accent.
spectrum. This is the case in L-accent standard. This option
is also built in for flexibility reasons.
It determines the tuner IF AGC output Pin mode. The
When AGC_TRI is set to logic 1 the tuner IF AGC output
When HIGH, the demodulator expects a swapped IF
Normal mode
Open-drain mode
Normal mode
3-state mode
polarity detector off
polarity detector on
negative video modulation
positive video modulation
normal IF spectrum expected
swapped IF spectrum expected
not used
ADC_HEADR adjusts the needed headroom for the
wanted channel’s own sound carriers and the N
adjacent sound carriers (PC in L-accent standard).
The ADC headroom is related to the sum of all
signals. This function is built in for debugging
purposes.
ADC headroom 3 dB
ADC headroom 6 dB
ADC headroom 9 dB
ADC headroom 12 dB
TDA8295
© NXP B.V. 2008. All rights reserved.
23 of 77
1