Part # AD724 datasheet

Part Manufacturer: Analog Devices

Analog Devices

Part Description: AD724 Data Sheet

Part Details:

a RGB to NTSC/PAL Encoder AD724 FEATURES operates from a single +5 V supply. No external delay lines or Low Cost, Integrated Solution filters are required. The AD724 may be powered down when +5 V Operation not in use. Accepts FSC Clock or Crystal, or 4FSC Clock The AD724 accepts either FSC or 4FSC clock. When a clock is Composite Video and Separate Y/C (S-Video) Outputs not available, a low cost parallel-resonant crystal (3.58 MHz Luma and Chroma Outputs Are Time Aligned (NTSC) or 4.43 MHz (PAL)) and the AD724 s on-chip oscilla- Minimal External Components: tor generate the necessary subcarrier clock. The AD724 also No External Filters or Delay Lines Required accepts the subcarrier clock from an external video source. Onboard DC ClampAccepts Either HSYNC and VSYNC or CSYNC The interface to graphics controllers is simple: an on-chip logic Phase Lock to External Subcarrier "XNOR" accepts the available vertical (VSYNC) and horizon- Drives 75 Reverse-Terminated Loads tal sync (HSYNC) signals and creates the composite sync Logic Selectable NTSC or PAL Encoding Modes (CSYNC) signal on-chip. If available, the AD724 will also Compact 16-Lead SOIC accept a standard CSYNC signal by connecting VSYNC toLogic HI and applying CSYNC to the HSYNC pin. The APPLICATIONS AD724 contains decoding logic to identify valid horizontal sync RGB to NTSC or PAL Encoding pulses for correct burst insertion. Delays in the U and V chroma filters are matched by an on-chip PRODUCT DESCRIPTION sampled-data delay line in the Y signal path. To prevent alias- The AD724 is a low cost RGB to NTSC/PAL Encoder that ing, a prefilter at 5 MHz is included ahead of the delay line and converts red, green and blue color component signals into their a post-filter at 5 MHz is added after the delay line to suppress corresponding luminance (baseband amplitude) and chromi- harmonics in the output. These low-pass filters are optimized nance (subcarrier amplitude and phase) signals in accordance for minimum pulse overshoot. The overall luma delay, relative with either NTSC or PAL standards. These two outputs are also to chroma, has been designed to be time aligned for direct input to combined to provide composite video output. All three outputs can a television s baseband. The AD724 comes in a space-saving simultaneously drive 75 , reverse-terminated cables. All logi- SOIC and is specified for the 0°C to +70°C commercial tem- cal inputs are TTL, 3 V and 5 V CMOS compatible. The chip perature range. FUNCTIONAL BLOCK DIAGRAM PHASE DETECTOR

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AD724.pdf Datasheet