TDA9874AHB View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'TDA9874AHB' PDF : 69 Pages View PDF
Philips Semiconductors
Digital TV sound demodulator/decoder
Product specification
TDA9874A
7.3.2 AGC GAIN REGISTER (AGCGR)
If the AGC function is switched off in the general
configuration register (see Section 7.3.3), the contents of
this register defines a fixed gain of the SIF input stage. The
input voltages given are meant to generate a nearly
full-scale output from the SIF ADC. If the AGC is on, the
AGC gain setting is ignored. After switching off the AGC
function, the latest gain control setting is copied to the
AGC gain register.
If the AGC input level shift bit AGCLEV is set to logic 1 the
input signal is scaled with −10 dB. The bit AGCLEV is also
active if the AGC function is enabled.
The default setting after Power-on reset is 0000 0000.
In Table 14 the stated step number corresponds with the
SIF level read from subaddress 7 (see Section 7.4.6); the
input voltages should be considered as approximate target
values.
Table 12 AGC gain register (subaddress 0)
7
6
5
0
0
AGCLEV
4
AGCB4
3
AGCB3
2
AGCB2
1
AGCB1
0
AGCB0
Table 13 Description of the AGC gain register bits
BIT
NAME
DESCRIPTION
7
−
this bit is not used and should be set to a logic 0
6
−
this bit is not used and should be set to a logic 0
5
AGCLEV If the AGC input level shift bit AGCLEV = 1 the input signal is scaled with −10 dB.
Bit AGCLEV is also active if the automatic gain function is enabled.
4
AGCB4 If the automatic gain control function is switched off in the general configuration register,
3
AGCB3 the contents of this register will define a fixed gain of the AGC stage.
2
AGCB2
1
AGCB1
0
AGCB0
2000 Aug 04
21
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