TDA8822 Datasheet, PDF (7/28 Pages) NXP Semiconductors – Universal I2C-bus programmable RF modulator

Philips Semiconductors
Universal I²C-bus programmable RF
modulator
Preliminary specification
TDA8822
Audio part
The audio part provides the following:
• The sound subcarrier is created in an integrated VCO.
The signal at the output of this VCO is fed to a stage that
adjusts the picture-to-sound ratio and to the audio
programmable divider.
• The frequency of the sound subcarrier is set by
programming the bits SC1 and SC0 of the I²C-bus (see
Table 2). These two bits set the dividing ratio of the
audio programmable divider to get the divided frequency
f_div(audio).
• The audio phase detector compares the
phase/frequency of the divided audio frequency f_div(audio)
and the reference frequency for the audio, f_ref(audio) and
drives the Charge Pump (CP) that charges or
discharges the audio loop filter connected between
pins ACP and AGND to get the VCO oscillating to the
programmed frequency.
• f_ref(audio) and f_div(audio) can be monitored on the general
purpose output port during a special test mode.
• The frequency deviation of the sound subcarrier is set
using 3 bits DEV2, DEV1 and DEV0 of the I²C-bus
programming (see Table 3), when a signal of 1 kHz with
a level of 50 mV (p-p) is applied on the audio input pin.
• The difference between the picture carrier level and the
sound subcarrier level is adjusted using 3 bits PS2, PS1
and PS0 (see Table 4).
• The NICAM amplifier has a constant gain, and is
designed for adding a second sound subcarrier in the TV
channel. This subcarrier can be either a second FM
carrier for dual-sound/stereo system used in PAL B/G or
a modulated NICAM carrier. The level between the
picture carrier and the NICAM carrier (P/N) will depend
on the input level on the NICAM input.
Table 2 Sound subcarrier frequency setting
SC SETTING
0
1
2
3
BIT
SC1
SC0
0
0
0
1
1
0
1
1
SOUND SUBCARRIER
FREQUENCY (MHz)
4.5
5.5
6.0
6.5
STANDARD
M, N
B, G
I
D, K
Table 3 Sound subcarrier frequency deviation setting (typical values)
DEV SETTING
0
1
2
3
4
5
6
7
DEV2
0
0
0
0
1
1
1
1
BIT
DEV1
0
0
1
1
0
0
1
1
DEV0
0
1
0
1
0
1
0
1
DEVIATION
(%)
40.0
45.0
50.5
56.5
63.5
71.5
80.0
90.0
DEVIATION (kHz)
B, G, I, D, K
M, N
20.0
10.0
22.5
11.3
25.3
12.6
28.3
14.1
31.8
15.9
35.8
17.9
40.0
20.0
45.0
22.5
1997 Jan 08
7