TDA8822T PHILIPS [NXP Semiconductors], TDA8822T Datasheet - Page 8

• Manufacturer Part Number: TDA8822T
• Description: Universal I2C-bus programmable RF modulator
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
Table 4 Picture-to-sound ratio setting (typical values)
RF part
The RF part provides the following:
1997 Jan 08
The RF oscillator can produce any frequency used for
TV transmission, from 35 to 890 MHz. The frequency
range depends on the components used in the
application (see Table 11).
The RF mixer combines the video signal, the sound
subcarrier and the carrier from the NICAM input to build
a baseband TV channel. This baseband signal is then
mixed with the RF oscillator signal to get the RF TV
channel.
The two signals from the RF mixer are sent to the output
buffer. This output buffer can be used either as two
asymmetrical outputs or as one symmetrical output.
The output buffer is switched-off while the PLL is not
in-lock, to avoid parasitic output signal during the tuning
of the RF oscillator. The in-lock information is given by
the phase detector of the loop.
The signal from the RF oscillator is fed to the PLL which
controls the picture carrier frequency. The RF signal is
first divided by 8 in the prescaler, and then divided in the
programmable 14-bits divider. The dividing ratio of this
divider is programmed via the I
frequency that can be synthesized is 16 MHz, and the
maximum frequency is 1023.9375 MHz.
The divided frequency called f
reference frequency called f
crystal oscillator and divided in the reference divider.
The crystal oscillator is intended to be used with a
crystal of 4 MHz.
The comparison between f
in the video phase detector. The resulting signal is fed
via the video charge pump to the loop amplifier,
including the tuning voltage drive (33 V) inside the IC.
Universal I
modulator
PS SETTING
0
1
2
3
4
5
6
7
2
C-bus programmable RF
ref(video)
ref(video)
div(video)
2
C-bus. The minimum
PS2
and f
0
0
0
0
1
1
1
1
coming from the
is compared to the
div(video)
is done
PS1
BIT
0
0
1
1
0
0
1
1
8
Software information
The transmission is made using 4 words in I
First the address CA has to be sent, then at least two
consecutive words have to be sent, either the two words
F1 and F0, or the two words C1 and C0.
The two words C1 and F1 are differentiated inside the IC
by the first bit being logic 1 or logic 0 respectively.
The contents of the 4 bytes is shown in Table 5.
At the power-up of the TDA8822, the I
following:
f
output port during a special test mode.
The I
control of:
– Picture carrier frequency
– Sound subcarrier frequency
– Sound subcarrier frequency deviation
– Video modulation depth
– Picture-to-sound ratio
– TPSG on/off and LED drive control
– RF oscillator on/off
– Sound oscillator on/off
– General purpose output port on/off
– Test modes setting.
N13 to N0 are not fixed
SC setting = 1: the sound carrier is fixed to 5.5 MHz
MD is set to 4 (82.5%), PS is set to 1 ( 12 dB) and DEV
is set to 2 (50.5%)
ref(video)
2
C-bus receiver and control logic includes the
PS0
0
1
0
1
0
1
0
1
and f
div(video)
can also be monitored on the
P/S RATIO
Preliminary specification
(dB)
12
13
14
15
16
17
18
11
2
C-bus state is the
TDA8822
2
C-bus format.