AD723It is a low-cost RGB to NTSC/PAL
encoder, which converts analog red, green, and blue component signals into corresponding luminance and chrominance signals for display on NTSC or PAL televisions. Luminance (Y) and chrominance (C) signals can be used independently for S-video or combined for composite video (CV). All outputs are available independently and optimized for driving 75 Ω load. To reduce power dissipation, the device uses active-terminal impedance.
The intelligent load detection feature shuts down unused outputs and can be used to monitor the presence of external TV signals for plug-and-play operation. In addition, a logic-controlled three-way switch at the input solves the application problem of providing different load conditions when the RGB monitor is off. When the RGB monitor is not present, the user can enable impedances at R, G, and B. When an RGB monitor is operating, this solution ensures that there is no loss of video bandwidth.
In PC applications, the graphics controller provides flicker filter support and direct access to memory. Underscan compensation for applications other than video or DVD can be supported by selecting the appropriate RGB output clock and synchronization interval.
An optional luminance notch (YTRAP) can be used to reduce crosstalk artifacts caused by subcarrier frequency information in the Y signal.
The AD723 is available in a 28-lead TSSOP package and operates from supplies from 2.7 V to 5.5 V.