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CXA3050M Dataheets PDF



Part Number CXA3050M
Manufacturers Sony Corporation
Logo Sony Corporation
Description NICAM and SMATV RF MODULATOR/PLL
Datasheet CXA3050M DatasheetCXA3050M Datasheet (PDF)

CXA3050M NICAM and SMATV RF MODULATOR/PLL 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 125kHz steps • Accepts NICAM 6.552MHz QPSK input signal • Accepts FM Stereo input signal • I2C control of: a. Video RF Carrier Frequency b. Sound Carrier Frequency c. Modulation Depth (±2% Typ.) d. FM Deviat.

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CXA3050M NICAM and SMATV RF MODULATOR/PLL 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 125kHz steps • Accepts NICAM 6.552MHz QPSK input signal • Accepts FM Stereo input signal • I2C control of: a. Video RF Carrier Frequency b. Sound Carrier Frequency c. Modulation Depth (±2% Typ.) d. FM Deviation (±8% Typ.) e. P/S ratio (±1dB Typ.) f. Nicam output enable to sleep g. Video RF carrier enable to sleep • On chip Regulator 3.1V Block Diagram Analog GND Analog VCC NICAM-in OSC VCC 24 pin SOP (Plastic) Structure Bipolar silicon monolithic IC Applications • PAL and NTSC System VCR • Satellite Receiver • Set Top Box • SMATV Recommended Operating Voltages (Ta = 25°C) • Supply voltage VCC 5.0 ± 0.5 V • Supply for VCO Varactor 30 ± 0.5 V • Operating Temperature –10 to +80 °C RF-OUT OSC GND OSC4 OSC1 OSC2 PDout 14 PLL 11 OSC3 24 23 22 21 20 19 18 17 16 15 13 AMP NICAM MIXER VIDEO MIXER AMP VCO AMP TPSG W/C-CLAMP FM-OSC REG PLL OSC PLL I2C-Interface 1 2 3 4 5 6 7 8 9 10 12 Vreg Digital-VCC Mod-adj Digital GND Audio-Loop filter Video-in Audio-in SCL 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. FM-Tank –1– SDA Xtal NC EF E96331A66-ST Multi-standard RF Modulator Audio Loop Audio Filter Tank SMATV Nicam in Analog VCC Ground Digital VCC Digital Ground Audio in NTSC Amp FM Mod PLL B RF Amp Mixer and Adder P/S control NICAM Mixer Switch Audio in PAL 62.5kHz RF Output A B Modulation depth Video in video limiter Modulation depth Video clamp Buffer ×2 OSC C D A Loop Filter Loop filter B –2– divide 8 Memory Latch CCT divide M Phase detector Regulator V Reg SDA I2C divide 25 4MHz OSC XTAL 4MHz B A 62.5kHz 250kHz SCL B 4MHz CXA3050M Fig. 1 CXA3050M 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 4.5MHz (NTSC) or 5.5, 6.0, 6.5MHz (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 2.0V). 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 1dB steps between the range 10dB and 17dB (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 15.625kHz. The reference signal is derived from a 4MHz crystal oscillator feeding a –256 divider. The UHF oscillator covers the frequency range 471MHz to 855MHz in frequency steps of 125kHz. This is adequate for the UHF NTSC and PAL TV channels (471.25MHz (CH21) to 855.25MHz (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 6.522MHz Nicam signal subcarri.


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