AD722JR-16-REEL

a FEATURES Low Cost, Integrated Solution +5 V Operation Accepts FSC Clock or Crystal, or 4FSC Clock Composite Video and Separate Y/C (S-Video) Outputs Minimal External Components: No External Filters or Delay Lines Required Onboard DC Restoration Accepts Either HSYNC & VSYNC or CSYNC Phase Lock to External Subcarrier Drives 75 Ω Reverse-Terminated Loads Logic Selectable NTSC or PAL Encoding Modes Compact 16-Pin SOIC APPLICATIONS RGB to NTSC or PAL Encoding RGB to NTSC/PAL Encoder AD722 The AD722 accepts either FSC or 4FSC clock. When a clock is not available, a low cost parallel-resonant crystal (3.58 MHz (NTSC) or 4.43 MHz (PAL)) and the AD722’s on-chip oscillator generate the necessary subcarrier clock. The AD722 also accepts the subcarrier clock from an external video source. The interface to VGA Controllers and MPEG Video Decoders is simple: an on-chip logic “XNOR” accepts the available vertical (VSYNC) and horizontal sync (HSYNC) signals and creates the composite sync (CSYNC) signal on-chip. If available, the AD722 will also accept a standard CSYNC signal by connecting VSYNC to +5 V and applying CSYNC to HSYNC pin. The AD722 contains decoding logic to identify valid HSYNC pulses for correct burst insertion. Delays in the U and V chroma filters are matched by an on-chip sampled-data delay line in the Y signal path. To prevent aliasing, a prefilter at 5 MHz is included ahead of the delay line and a post-filter at 5 MHz is added after the delay line to suppress harmonics in the output. These low-pass filters are optimized for minimum pulse overshoot. The overall luma delay, relative to chroma, has been designed to be 170 ns, which precompensates for delays in the filters used in the IF section of a television receiver. This precompensation delay is already present in TV broadcasts. The AD722 comes in a space-saving SOIC and is specified for the 0°C to +70°C commercial temperature range. PRODUCT DESCRIPTION The AD722 is a low cost RGB to NTSC/PAL Encoder that converts red, green and blue color component signals into their corresponding luminance (baseband amplitude) and chrominance (subcarrier amplitude and phase) signals in accordance with either NTSC or PAL standards. These two outputs are also combined to provide composite video output. All three outputs can simultaneously drive 75 Ω, reverse-terminated cables. All logical inputs are CMOS compatible. The chip operates from a single +5 V supply. No external delay lines or filters are required. The AD722 may be powered down when not in use. FUNCTIONAL BLOCK DIAGRAM SUBCARRIER FSC XOSC 4FSC NTSC/PAL HSYNC VSYNC 4FSC SYNC SEPARATOR XNOR CSYNC 4FSC QUADRATURE +4 DECODER BURST FSC BURST FSC 90° PHASE DETECTOR CHARGE PUMP FILTER LOOP CSYNC NTSC/PAL SC 90°/270° 4FSC VCO ±180° (PAL ONLY) FSC 0° NTSC/PAL CLOCK AT 4FSC RED DC CLAMP Y 3-POLE LP PREFILTER CSYNC INSERTION SAMPLEDDATA DELAY LINE 2-POLE LP POSTFILTER NTSC/PAL X2 LUMINANCE OUTPUT COMPOSITE OUTPUT CHROMINANCE OUTPUT GREEN DC CLAMP RGB-TO-YUV ENCODING MATRIX U 4-POLE LPF U CLAMP BALANCED MODULATORS X2 BLUE DC CLAMP V 3-POLE LPF 3.6MHz (NTSC) 4.4MHz (PAL) X2 4-POLE LPF V CLAMP REV. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. © Analog Devices, Inc., 1995 One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703 AD722–SPECIFICATIONS 150 Ω ± 5% at the IC pins. Outputs are measured at the 75 Ω reverse terminated load.) Parameter SIGNAL INPUTS (RDIN, GRIN, BLIN) Input Amplitude Black Level Input Resistance1 Input Capacitance LOGIC INPUTS (SYNC, FSC, ENCD, NTSC) Logic LO Input Voltage Logic HI Input Voltage Logic LO Input Current (DC) Logic HI Input Current (DC) VIDEO OUTPUTS2 Luminance (LUMA) Roll-off @ 5 MHz Gain Error Linearity Sync Level DC Black Level Chrominance (CRMA) Bandwidth Color Burst Amplitude Color Signal to Burst Ratio Error Color Burst Width Phase Error3 DC Black Level Chroma Feedthrough Chroma/Luma Time Alignment Composite (COMP) Absolute Gain Error Differential Gain Differential Phase DC Black Level POWER SUPPLIES Recommended Supply Range Quiescent Current—Encode Mode Quiescent Current—Power Down R, G, B = 0 Conditions NTSC PAL Red, Green, Blue CMOS Logic Levels 1 4