Sony CXA1929M Datasheet

TV RF MODULATOR/PLL

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Description

Fully synthesized I2C 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

• I2C 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

CXA1929M

24 pin SOP (Plastic)

Applications

• PAL and NTSC System VCR

• Satellite Receiver

• Set Top Box

Structure

Bipolar silicon monolithic IC

Recommended Operating Voltages (Ta=25 °C)

• Supply voltage VCC 5.0±0.5 V

• Supply for VCO Varactor –30 to +0.5 °C

• Operating Temperature –10 to +80 °C

Block Diagram

OSC V

AMP

PLL

FM-Tank

Audio-Loop

OSC4

TPSG

filter

Analog GND

RF-OUT

AMP

W/C-CLAMP

REG

Vreg

Video-in

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.

Analog V

MOD-adj

VIDEO MIXER

FM-OSC

3 8

Audio-in

PAL

Audio-in

NTSC

OSC3

VCO

OSC

7 91 2 4 5 6

Digital GND

OSC2

Xtal

OSC1

151620212223 1924 13141718

Digital-V

OSC GND

I2C-Interface

1110 12

SCL

PDout

PLL

SDA

ATT

Driver

A-driver

—1—

E96514-TE

Digital

Ground

RF Output

CXA1929M

Loop filter

XTAL

4MHz

Analog Digital

Audio

Loop

Audio

CC Ground

Tank

Filter

P/S

control

PLL

FM Mod

RF Amp

and

Mixer

Adder

OSC

× 2

Buffer

depth

Modulation

Loop

divide

Filter

OSC

4MHz

divide

Phase

detector

divide

B A

62.5kHz 250kHz

Regulator

ATT

Driver

V Reg

out

Driver

Amp

Switch

Audio in

NTSC

Multi-standard RF Modulator

62.5kHz

Audio in

PAL

Modulation

depth

video

limiter

Video

clamp

Video in

—2—

OSC

TPSG

Latch

Memory

SDA

CCT

4MHz

SCL

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 I2C 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 I2C, 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 I2C control. The design of the FM modulator eliminates the need for an external varactor.

The amplitude of the FM signal is varied via I2C 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 I2C 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 I2C control will switch the Nicam signal output off or on.

—3—

I2C Interface Data format

CXA1929M

Modulator Address

Data 1 Data 2 Data 3 Data 4

1100100R/Wask

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

00 01 10 11

Sound Carrier

Frequency

4.5 MHz

5.5 MHz

6.0 MHz

6.5 MHz

Sound Carrier Fine Adjust

ADJ1 ADJ0

00 01 10 11

df Adjust

–f

Normal

+f +f

TV System

(Pre-emphasis)

NTSC

PAL PAL PAL

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 M12–MO Main divider control data 13 bits S1–S0 Sound carrier frequency selection 2 bits ADJ1–ADJ0 Sound carrier frequency adjust (0 to 6.4 RF) 2 bits MD2–MD0 Modulation Depth 3 bits PS2–PS0 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

—4—

CXA1929M

Software Application Notes

The minimum requirement to drive the CXA3050 and I2C 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.

Normal Status

1/0

2 to 8191

4 4

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

Attenuator Driver

1/0

Output logic ON/OFF

—5—

Pin Description

CXA1929M

No.

Reference

Video-in

Vreg

Pin Voltage

Typical DC

2.5 V

3.1 V

Equivalent circuit

VCC

Video input

Chip voltage supply regulator

Description

NTSC

Audio-in

PAL

Audio-in

FM-Tank

2.5 V

10 mA

4.0 V

NTSC Audio input

PAL Audio input

Sound Carrier oscillator tank

—6—

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