TDA8295 Datasheet, PDF (33/77 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
9.3.9 Tuner IF AGC functions
Table 29. T_IF_AGC_SET register (address 15h) bit description
Legend: * = default value.
Bit Symbol
Access Value
Description
7
POL_TIF
R/W
tuner IF AGC polarity
0
inverted tuner IF AGC polarity
1*
normal tuner IF AGC polarity: the higher
the necessary gain, the higher the IF
AGC voltage
6 to 0 T_IF_AGC_SPEED[6:0] R/W
T_IF_AGC_SPEED determines the tuner
IF AGC loop speed
000 0001 −18 dB nominal
000 0010 −12 dB nominal
000 0100 −6 dB nominal
000 1000* nominal speed (determined by the tuner
IF control slope)
001 0000 +6 dB nominal
010 0000 +12 dB nominal
100 0000 +18 dB nominal
Table 30. T_IF_AGC_LIM register (address 16h) bit description
Legend: * = default value.
Bit Symbol
Access Value Description
7 to 4 UP_LIM[3:0] R/W
The tuner IF AGC output voltage can be limited to
interface with concepts having power supply < 3.3 V.
UP_LIM determines the upper limit from ¹â„₂ FS (= 0h) to
FS (= Fh). The format is straight binary.
1111* set upper limit to maximum
3 to 0 LOW_LIM[3:0] R/W
LOW_LIM determines the lower tuner IF AGC output
limit from 0 (= 0h) to ¹â„₂ FS (= Fh). The format is straight
binary.
0000* set lower limit to minimum
TDA8295_1
Product data sheet
Table 31. T_IF_AGC_FORCE register (address 17h) bit description
Legend: * = default value.
Bit Symbol
Access Value Description
7
T_FORCE
R/W
the tuner IF AGC output voltage can be forced
externally to a fixed voltage, determined by
T_FORCE_VAL
0*
tuner IF AGC normal operation
1
tuner IF AGC output voltage determined by
T_FORCE_VAL
6 to 0 T_FORCE_VAL[6:0] R/W
T_FORCE_VAL determines the tuner IF AGC
forced value. So the tuner IF AGC can be fixed to
a certain value for debugging purposes. Format is
straight binary.
3Fh*
XXh
0.5 × V_DD(3V3), i.e. 1.65 V nominally
don’t care if T_FORCE = 0
Rev. 01 — 4 February 2008
© NXP B.V. 2008. All rights reserved.
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