AD725ARZ Analog Devices Inc, AD725ARZ Datasheet
AD725ARZ
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AD725ARZ Summary of contents
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FEATURES Composite Video Output: Both NTSC and PAL Chrominance and Luminance (S-Video) Outputs Luma Trap Port to Eliminate Cross Color Artifacts TTL Logic Levels Integrated Delay Line and Auto-Tuned Filters Drives 75 Reverse-Terminated Loads Low Power +5 V Operation ...
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AD725–SPECIFICATIONS Parameter SIGNAL INPUTS (RIN, GIN, BIN) Input Amplitude 1 Black Level 2 Input Resistance Input Capacitance LOGIC INPUTS (HSYNC, VSYNC, 4FSC, CE, STND) Logic Low Input Voltage Logic High Input Voltage Logic Low Input Current (DC) Logic High Input ...
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ABSOLUTE MAXIMUM RATINGS* Supply Voltage, APOS to AGND . . . . . . . . . . . . . . . . . . +6 V Supply Voltage, DPOS to DGND . . . . . . . ...
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AD725 Pin Mnemonic Description 1 STND Encoding Standard Pin. A Logic HIGH input selects NTSC encoding. A Logic LOW input selects PAL encoding. TTL Logic Levels. 2 AGND Analog Ground Connection. 3 4FSC 4FSC Clock Input. For NTSC: 14.318 180 ...
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FSC (3.579545MHz OR 4.433618MHz) OSCILLATOR 1.0 APL = 50.8% 525 LINE NTSC SLOW CLAMP TO 0.00V @ 6.63 s 0.5 0.0 –0 µs Figure 3. 100% Color Bars, NTSC Figure 4. 100% Color Bars on ...
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AD725–Typical Characteristics 1.0 APL = 46.6% 525 LINE NTSC NO FILTERING SLOW CLAMP TO 0.00V @ 6.63 s 0.5 0.0 –0 Figure 7. Modulated Pulse and Bar, NTSC 200mV Figure 8. Zoom on Modulated ...
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APL = 48.2% 525 LINE NTSC SLOW CLAMP TO 0.00V @ 6.63 s 0.5 0.5MHz 1MHz 2MHz 0.0 –0 Figure 11. Multiburst, NTSC H TIMING MEASUREMENT RS–170A (NTSC) FIELD = 1 LINE = 22 ...
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AD725 THEORY OF OPERATION The AD725 is a predominantly analog design, with digital logic control of timing. This timing logic is driven by a external fre- quency reference at four times the color subcarrier frequency, input into the 4FSC pin ...
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The reconstructed luma signal is then smoothed with a two pole Bessel low-pass filter. This filter has a –3 dB bandwidth of 5.25 MHz for NTSC, 6.5 MHz for PAL. A final buffer pro- vides current drive for the LUMA ...
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AD725 HSYNC/VSYNC (USER INPUTS) RIN/GIN BIN (USER INPUTS) MODULATOR RESTORE INPUT CLAMPS BURST FLAG/ DELAY LINE RESET LUMA CRMA Symbol Name t Sync Width SW t Sync to Blanking SB End t Sync to Modulator SM Restore t Modulator Restore ...
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APPLYING THE AD725 Inputs RIN, BIN, GIN are analog inputs that should be terminated to ground with 75 in close proximity to the IC. When properly terminated the peak-to-peak voltage for a maximum input level should be 714 mV p-p. ...
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AD725 Displaying VGA Output The AD725 can be used to convert the analog RGB output from a personal computer’s VGA card to the NTSC or PAL television standards. To accomplish this it is important to understand that ...
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Low Cost Crystal Oscillator A low cost oscillator can be made that provides a CW clock that can be used to drive both the AD725 4FSC and other devices in the system that require a clock at this frequency. Figure ...
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AD725 Vertical Scaling In addition to converting the computer generated image from noninterlaced to interlaced format also necessary to scale the image down to fit into NTSC or PAL format. The most common vertical lines/screen for VGA display ...
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All signals in this band are processed as chroma information since the chroma processing circuit has no knowledge as to where these signals originated. Therefore, the color that results from the luma signals in the chroma ...
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AD725 Measuring the Luma Trap Frequency Response The frequency response of the luma trap can be measured in two different ways. The first involves using an RGB frequency sweep input pattern into the AD725 and observing the compos- ite output ...
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COMP PIN –6 –9 –12 –15 –18 –21 –24 0.1 1.0 FREQUENCY – MHz Figure 25. Luminance Frequency Response with NTSC Trap SYNCHRONIZING SIGNALS The AD725 requires explicit horizontal and vertical synchroniz- ing signals for proper ...
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AD725 0.0118 (0.30) 0.0040 (0.10) OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 16-Lead Wide Body SOIC (R-16) 0.4133 (10.50) 0.3977 (10.00 0.1043 (2.65) 0.0291 (0.74) PIN 1 0.0926 (2.35) 0.0098 (0.25) 0.0500 (1.27) 8° 0.0500 ...
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