--1--
E96514-TE
Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by
any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the
operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.
Applications
PAL and NTSC System VCR
Satellite Receiver
Set Top Box
Structure
Bipolar silicon monolithic IC
Recommended Operating Voltages (Ta=25 C)
Supply voltage
V
CC
5.00.5
V
Supply for VCO Varactor
30 to +0.5
C
Operating Temperature
10 to +80
C
Description
Fully synthesized I
2
C controlled UHF/VHF TV RF
Modulator compatible with PAL and NTSC video
formats.
Features
Minimal adjustment of external components
For use on VHF and UHF TV Frequencies
Video RF carrier frequency programmable in 125
kHz steps
ATT Driver
I
2
C control of:
a. Video RF Carrier Frequency
b. Sound Carrier Frequency
c. Modulation Depth (2.5 % Typ.)
d. FM Deviation (7 % Typ.)
e. P/S ratio (1 dB Typ.)
f. Nicam output enable to sleep
g. Video RF carrier enable to sleep
On chip Regulator 3.1 V
TV RF MODULATOR/PLL
24 pin SOP (Plastic)
Block Diagram
PLL
I
2
C-Interface
OSC
TPSG
REG
AMP
VIDEO
MIXER
PLL
VCO
AMP
W/C-CLAMP
PLL
ATT
Driver
FM-OSC
A-driver
SDA
SCL
Digital-V
CC
Xtal
Digital GND
Audio-Loop
filter
FM-Tank
PAL
Audio-in
NTSC
Audio-in
Vreg
Video-in
RF-OUT
Analog GND
Analog V
CC
MOD-adj
OSC V
CC
OSC4
OSC3
OSC2
OSC1
OSC GND
PDout
EF
15
16
20
21
22
23
19
24
13
14
17
18
7
9
1
2
4
5
6
11
10
12
3
8
CXA1929M
For the availability of this product, please contact the sales office.
--3--
CXA1929M
Functional Description of RF Modulator System
A block diagram of the RF modulator is shown in Fig. 1.
The composite video signal passes through an amplitude limiting circuit and a digitally controlled modulation
depth adjustment circuit. By means of three allocated I
2
C control bits it is possible to adjust the modulation
depth from a nominal 74 % to 86% in 2.0 % steps. Modulation depth can also be controlled externally by
addition of an external resistor on pin3. The video signal is then passed through to the mixer. In the mixer
stage, both the video composite signal and FM sound carrier amplitude modulate the RF carrier from the UHF
OSC, and the issuing signal is fed to the output via an RF amplifier.
The audio signals enter the chip via pin4. The FM Voltage Controlled Oscillator is band-switched to the
approximate centre frequencies of the four sound carrier frequencies 4.5 MHz (NTSC) or 5.5, 6.0, 6.5 MHz
(PAL). The required correct audio carrier frequency is fine tuned by the adjustment of fsound via I
2
C, where
upon the FM phase locked loop will lock the VCO onto the exact centre frequency. Minimum distortion of the
FM signal occurs when the centre frequency of the oscillator coincides with a mid-rail control voltage (to 2.0 V).
Hence fine adjustment capacitors are also integrated on the chip, which tag into account any capacitance
variations from one batch to another. This is achieved by fine adjustment of Delta fsound via I
2
C control. The
design of the FM modulator eliminates the need for an external varactor.
The amplitude of the FM signal is varied via I
2
C by a digitally controlled logarithmic gain stage, which controls
the picture to sound power ratio (P/S). This signal is then fed into the RF amp. Hence at the RF output the
P/S ratio can be programmed in 1 dB steps between the range 10 dB and 17 dB (see Electrical
Characteristics). Audio sensitivity can be programmed in 8 % steps between the range 32 % and +24 %.
The UHF is phase locked to the reference frequency by means of the UHF phase locked loop. The VCO
output passes through a prescaler (
8) followed by an I
2
C controlled programmable divider (
M), and then
phase compared with that of a reference signal at 15.625 kHz. The reference signal is derived from a 4 MHz
crystal oscillator feeding a 256 divider. The UHF oscillator covers the frequency range 471 MHz to 855 MHz
in frequency steps of 125 kHz. This is adequate for the UHF NTSC and PAL TV channels (471.25MHz (CH21)
to 855.25 MHz (CH69)). By adjustment of the external components around the oscillator and some adjustment
to output matching the RF modulator can also achieve range of frequencies in the VHF range.
The Nicam input (pin 22) accepts the 6.522 MHz Nicam signal subcarrier QPSK at 728 K bits/s data. This is
then buffered and feed into a separate mixer (controlled via VCO). This then feeds to the RF amp with the
composite video and audio. The I
2
C control will switch the Nicam signal output off or on.
--4--
CXA1929M
I
2
C Interface Data format
Modulator Address
Data 1
Data 2
Data 3
Data 4
1
1
0
0
1
0
0
R/W
ask
RF
ADJ1
ADJ0
S1
S0
TPSG
OVM
ATT
ask
M12
M11
M10
M9
M8
M7
M6
M5
ask
M4
M3
M2
M1
M0
MD2
MD1
MD0
ask
--
OSC
FM2
FM1
FM0
PS2
PS1
PS0
ask
Sound Carrier Course Adjust
S1
S0
0
0
0
1
1
0
1
1
Sound Carrier
Frequency
4.5 MHz
5.5 MHz
6.0 MHz
6.5 MHz
TV System
(Pre-emphasis)
NTSC
PAL
PAL
PAL
Sound Carrier Fine Adjust
ADJ1
ADJ0
0
0
0
1
1
0
1
1
df Adjust
f
Normal
+f
+f
on chip
capacitance
6.4 pF
3.2 pF
1.6 pF
0
RF
RF Power on (RF Amp & RF Mixer Driver)
1 bit
TPSG
TEST Pattern Signal Generator
1 bit
ATT
Local/distance external attenuator driver
1 bit
OSC
Oscillator ON/OFF switch
1 bit
OVM
Over Modulation Test
1 bit
M12MO
Main divider control data
13 bits
S1S0
Sound carrier frequency selection
2 bits
ADJ1ADJ0
Sound carrier frequency adjust (0 to 6.4 RF)
2 bits
MD2MD0
Modulation Depth
3 bits
PS2PS0
Picture/Sound control
3 bits
FM
FM deviation adjust
3 bits
M12
MO
Main UHF PLL Divider
MSB
LSB
8191 to 2
Video Carrier frequency calculated from = 125 (M+2) kHz
--5--
CXA1929M
Software Application Notes
The minimum requirement to drive the CXA3050 and I
2
C bus drive is a 386/486 with 4 M bytes hard disk
space, 16 MHz clock speed and running DOS5.00 or above. Insert the disc into the drive and type TESTS and
at the prompt type iic. At this there should appear a single list of user friendly functional tests that can be
changed by keyboard manipulation. As an aid the test list is written below. Note Page up increments the
status, page down decrements the status.
Function
RF Output Power
Delta Sound
Fsound
Frequency mode
Mod depth
FM deviation
P/S Ratio
Over Mod
TPSG
OSC on.
Attenuator Driver
Normal Status
1/0
1
0
2 to 8191
4
4
4
1/0
1/0
1/0
1/0
Comments
Turns RF Amp on/off
Fine tune audio carrier
Course adjust for
4.5 MHz (0)
5.5 MHz (1)
6.0 MHz (2)
6.5 MHz (3)
Check listing on page 10 for
frequency to hex conversation
Ranges mod depth from
72 % to (4)
Sensitivity adjustable
Programmable in 8 steps of 1 dB
Increase Video modulation ratio
Sets internal test pattern
generator ON/OFF
Turns oscillator ON/OFF
Output logic ON/OFF
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