TDA9874A Philips Semiconductors, TDA9874A Datasheet - Page 29

• Manufacturer Part Number: TDA9874A
• Description: Digital TV sound demodulator/decoder
• Manufacturer: Philips Semiconductors

Philips Semiconductors
10.3.2
If the Automatic Gain Control (AGC) function is switched off in the general configuration register (see Section 10.3.3) 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 HIGH the input signal is scaled with 10 dB. The AGCLEV bit is also active if the AGC function is enabled.
The default setting after power-on reset is ‘0000 0000’.
In Table 16 the stated step number corresponds with the SIF level read from subaddress 7 (see Section 10.4.6); the input
voltages should be considered as approximate target values.
Table 14 AGC gain register (subaddress 0)
Table 15 Description of the AGCGR bits
1999 Dec 03
Digital TV sound demodulator/decoder
BIT
7
0
7
6
5
4
3
2
1
0
AGC G
AIN
AGCLEV
AGCB4
AGCB3
AGCB2
AGCB1
AGCB0
NAME
R
EGISTER
6
0
(AGCGR)
this bit is not used and should be set to a logic 0
this bit is not used and should be set to a logic 0
If the AGC input level shift bit AGCLEV is set to HIGH the input signal is scaled with
If the automatic gain control function is switched off in the general configuration register,
the contents of this register will define a fixed gain of the AGC stage.
10 dB. The AGCLEV bit is also active if the automatic gain function is enabled.
AGCLEV
5
AGCB4
4
29
AGCB3
3
DESCRIPTION
AGCB2
2
AGCB1
Preliminary specification
1
TDA9874A
AGCB0
0